SR-700-005-03 (2)
Hazard Mitigation Plan
City of Santa Monica, CA
WORKING DRAFT
9/21/2004
Primary Point of Contact
Paul Weinberg
Emergency Services Coordinator
Santa Monica Fire Department
333 Olympic Drive
Santa Monica, CA 90401
310 458 8686 (Office)
pa ul-weinberg@santa-monica.org
City of Santa Monica
Natural Hazards Mitigation Plan
TABLE OF CONTENTS
Section 1 - Mitigation Action Plan
Execu tive Sum ma ry ............... ................................................. ....................... 1
1.1 Introduction ........................................................................................... 9
1.2 Commu nity Profile............................................................................27
1.3 Risk Assessment ................................................................................32
1.4 Mitigation Goals .................................................................................35
1. 5 Mitigation Actio n Items ...................................................................38
1.6 Plan Maintenance ..............................................................................43
Section 2 - Specific Natural Hazards
2.1 Ea rthq u a ke..........................................................................................49
2.2 La nd s lid e......................... ................................................. .....................7 8
2.3 Flo od _................................ ................................................. .....................9 2
2.4 T su n ami ........................... ................................................. ..................12 0
2.5 Wildfires .............................................................................................133
2.6 Severe Windstorm/Thunderstorm ...........................................151
Section 3 - Resources
Appendix A: Resource Directory ...........................................................A-l
Appendix B: Public Participation Process ...........................................B-l
Appendix C: Economic Analysis of Natural Hazard Mitigation
Proj ects... ................................................. ................... C-l
Append ix D: List of Acro nyms _...............................................................D-l
Append ix E: Glossa ry................................................................................E-l
EXECUTIVE SUMMARY
Five -Year Action Plan Matrix
The City of Santa Monica Natural Hazards Mitigation Action Plan includes
resources and information to assist City residents, public and private sector
organizations, and others interested in participating in planning for natural
hazards. The mitigation plan provides a list of activities that may assist City
of Santa Monica in reducing risk and preventing loss from future natural
hazard events. The action items address multi-hazard issues, as well as
activities for earthquakes, landslides, flooding, tsunamis, wildfires and severe
wi ndstormsjth u nderstorms.
How is the Plan Organized?
The Mitigation Plan contains a five-year action plan matrix, background on
the purpose and methodology used to develop the mitigation plan, a profile
of City of Santa Monica, sections on six natural hazards that occur within the
City, and a number of appendices. All of the sections are described in detail
in section 1.1, the plan introduction.
Planning Process
The City of Santa Monica has been working on the LHMP since the initial OES
DMA2K training workshop in June of 2003. The City's Emergency Services
Coordinator attended the three-day workshop. Upon returning, the LHMP
was put on the agenda of the CitY-Wide Department Heads meeting in July,
and a LHMP working group and steering committee was established. The
working group began addressing a strategy for the development of the Plan
immediately. The Santa Monica City Council approved the creation of the
LHMP in September of 2003. Work on the Plan continued over the next year
in a number of committees throughout the City. These committees included:
. Department Head Meetings
. The Emergency Operations Center Team
. The Public Information Team
. The Disaster Recovery Organization
. Several Department staff meetings from most City Departments
. Local Hazard Mitigation Planning Committee
Who Participated in Developing the Plan?
The City of Santa Monica Natural Hazards Mitigation Action Plan is the result
of a collaborative effort between City of Santa Monica citizens, publiC
agencies, non-profit organizations, the private sector, and regional and state
organizations. Public participation played a key role in development of goals
and action items. Interviews were conducted with stakeholders across the
City, and a publiC workshop and survey were conducted to include City of
Santa Monica residents in plan development. A project Steering Committee
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gUided the process of developing the plan.
The Steering Committee was comprised of representatives from:
City of Santa Monica Building and Safety
City of Santa Monica Fire Department
City of Santa Monica Finance
City of Santa Monica Police Department
City of Santa Monica Information Systems
City of Santa Monica GIS
City of Santa Monica Planning
City of Santa Monica Disaster Recovery Organization
City of Santa Monica Rent Control
City of Santa Monica Human Services Administration
City of Santa Monica Community and Cultural Services
City of Santa Monica City Manager's Office
City of Santa Monica Airport
City of Santa Monica City TV
Santa Monica Red Cross
What is the Plan Mission?
The mission of the City of Santa Monica Natural Hazards Mitigation Plan is to
promote sound publiC policy designed to protect citizens, critical facilities,
infrastructure, private property, and the environment from natural hazards.
This can be achieved by increasing publiC awareness, documenting the
resources for risk reduction and loss-prevention, and identifying activities to
gUide the City towards building a safer, more sustainable community.
What are the Plan Goals?
The plan goals describe the overall direction that City of Santa Monica
agencies, organizations, and citizens can take to work toward mitigating risk
from natural hazards. The goals are stepping-stones between the broad
direction of the mission statement and the specific recommendations outlined
in the action items.
Goal #1: Increase Public Awareness of Local Hazards
Description: Increase publiC awareness and understanding, support,
and demand for hazard mitigation.
Objectives:
. Heighten publiC awareness of the full range of natural hazards
they may face.
. Educate the publiC on actions they can take to prevent or reduce
the loss of life and/or property from all hazards.
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. Publicize and encourage the adoption of appropriate hazard
mitigation measures.
Goal #2: Protection of Lives and Property
Description: Implement activities that assist in protecting lives by
making homes, businesses, infrastructure, critical facilities, and other
property more resistant to natural hazards.
Objectives:
. Advise public about health and safety precautions to protect
from injury and loss.
. Assess the feasibility of warning and communication
technologies to mitigate damage from natural hazards.
. Reduce damage to enhance protection of dangerous areas
during hazardous events.
. Protect critical facilities and services.
. Ensure Emergency Services and critical facilities are included in
mitigation strategies.
Goal #3: Promote Sustainable Living
Description: Promote development in a sustainable manner.
Objectives:
. Incorporate hazard mitigation into long-range planning and
development activities.
. Promote beneficial use of hazardous areas while expanding open
space and recreational opportunities.
. Utilize regulatory approaches to prevent creation of future
hazards to life and property.
Goal #4: Partnerships and Implementation
Description: Build and support local partnerships to continuously
become less vulnerable to natural hazards.
Objectives:
. Build and support local partnerships with stakeholders in the
community.
. Build a cadre of committed volunteers to safeguard the
community before, during, and after a disaster.
. Build hazard mitigation concerns into City planning and
budgeting process.
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Goal #5: Strengthen Emergency Services Capability
Description: Establish policies and procedures to ensure mitigation
projects for critical facilities, services, and infrastructure.
Objectives:
. Provide training to City departments and non-City entities on
mitigation programs and techniques that could be incorporated
into a variety of projects.
. Strengthen emergency operations by increasing collaboration
and coordination among public agencies, non-profit
organizations, business, and industry.
How are the Action Items Organized?
The action items are a listing of activities in which City agencies and citizens
can be engaged to reduce risk. Each action item includes an estimate of the
time line for implementation. Short-term action items are activities that City
agencies may implement with existing resources and authorities within one
to two years. Long-term action items may require new or additional
resources or authorities, and may take between one and five years (or more)
to implement.
The action items are organized within the following matrix, which lists all of
the multi-hazard and hazard-specific action items included in the mitigation
plan. Data collection and research and the public participation process
resulted in the development of these action items (see Appendix B). The
matrix includes the following information for each action item:
Coordinating Organization. The coordinating organization is the
public agency with regulatory responsibility to address natural
hazards, or that is willing and able to organize resources, find
appropriate funding, or oversee activity implementation, monitoring,
and evaluation. Coordinating organizations may include local, county,
or regional agencies that are capable of or responsible for
implementing activities and programs.
Timeline. Action items include both short and long-term activities.
Each action item includes an estimate of the time line for
implementation. Short-term action items are activities which City
agencies are capable of implementing with existing resources and
authorities within one to two years. Long-term action items may
require new or additional resources or authorities, and may take
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DRAFT Santa Monica Hazard Mitigation Plan
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between one and five years (or more) to implement.
Ideas for Implementation. Each action item includes ideas for
implementation and potential resources, which may include grant
programs or human resources.
Plan Goals Addressed. The plan goals addressed by each action
item are included as a way to monitor and evaluate how well the
mitigation plan is achieving its goals once implementation begins. The
plan goals are organized into the following five areas:
1. Emergency Services Capability
2. Partnerships and Implementation
3. Promote Sustainable Living
4. Protection of Lives and Property
5. Public Awareness of Local Hazards
Partner Organizations. The Partner organizations are not listed with
the individual action items or in the plan matrix. Partner organizations
are listed in Appendix A, of this plan and are agencies or public/private
sector organizations that may be able to assist in the implementation
of action items by providing relevant resources to the coordinating
organization. The partner organizations listed in the Resource
Directory of the City of Santa Monica Natural Hazards Mitigation Plan
are potential partners recommended by the project steering
committee, but were not necessarily contacted during the
development of the Mitigation Plan. Partner organizations should be
contacted by the coordinating organization to establish commitment of
time and resources to action items.
Constraints. Constraints may apply to some of the action items.
These constraints may be a lack of city staff, lack of funds, or vested
property rights which might expose the City to legal action as a result
of adverse impacts on private property.
How Will the Plan be Implemented, Monitored, and Evaluated?
The Plan Maintenance Section of this document details the formal process
that will ensure that the City of Santa Monica Natural Hazards Mitigation Plan
remains an active and relevant document. The plan maintenance process
includes a schedule for monitoring and evaluating the Plan annually and
producing a plan revision every five years. This section describes how the
City will integrate public participation throughout the plan maintenance
process. Finally, this section includes an explanation of how City of Santa
Monica government intends to incorporate the mitigation strategies outlined
in this Plan into existing planning mechanisms such as the City's General
Plan, Capital Improvement Plans, and Building & Safety Codes.
A City of Santa Monica Hazard Mitigation Advisory Committee will be
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DRAFT Santa Monica Hazard Mitigation Plan
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responsible for coordinating implementation of Plan action items and
undertaking the formal review process. The existing Disaster Recovery
Group, which is comprised of the Hazard Mitigation Executive Committee, will
be responsible for on-going plan implementation, monitoring and evaluation.
Plan Adoption
Adoption of the Natural Hazard Mitigation Plan by the local jurisdiction's
governing body is one of the prime requirements for approval of the plan.
Once the plan is completed, the City Council will be responsible for adopting
the City of Santa Monica Natural Hazards Mitigation Plan. The local agency
governing body has the responsibility and authority to promote sound publiC
poliCY regarding natural hazards. The City Council will periodically need to
re-adopt the plan as it is revised to meet changes in the natural hazard risks
and exposures in the community. The approved Natural Hazard Mitigation
Plan will be significant in the future growth and development of the
community.
Convener
The City Council will adopt the City of Santa Monica Natural Hazard Mitigation
Plan, and the Hazard Mitigation Advisory Committee will take responsibility
for plan implementation. The co-chairs will serve as a convener to facilitate
the Hazard Mitigation Advisory Committee meetings, and will assign tasks
such as updating and presenting the Plan to the members of the committee.
Plan implementation and evaluation will be a shared responsibility among all
of the Natural Hazard Advisory Committee Members. This will include the
Disaster Recovery Organization as the main steering committee for Plan
maintenance.
Implementation through Existing Programs
The City of Santa Monica addresses statewide planning goals and legislative
requirements through its General Plan, Capital Improvement Plans, and City
Building & Safety Codes. The Natural Hazard Mitigation Plan proVides a
series of recommendations that are closely related to the goals and
objectives of these existing planning programs. The City of Santa Monica will
have the opportunity to implement recommended mitigation action items
through existing programs and procedures.
Economic Analysis of Mitigation Projects
The Federal Emergency Management Agency's approaches to identify costs
and benefits associated with natural hazard mitigation strategies or projects
fall into two general categories: benefit/cost analysis and cost-effectiveness
analysis. Conducting benefit/cost analysis for a mitigation activity can assist
communities in determining whether a project is worth undertaking now, in
order to avoid disaster-related damages later. Cost-effectiveness analysis
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DRAFT Santa Monica Hazard Mitigation Plan
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evaluates how best to spend a given amount of money to achieve a specific
goal. Determining the economic feasibility of mitigating natural hazards can
provide decision makers with an understanding of the potential benefits and
costs of an activity, as well as a basis upon which to compare alternative
projects.
Formal Review Process
The City of Santa Monica Natural Hazards Mitigation Plan will be evaluated on
an annual basis to determine the effectiveness of programs, and to reflect
changes in land development or programs that may affect mitigation
priorities. The evaluation process includes a firm schedule and time line, and
identifies the local agencies and organizations participating in plan
evaluation. The convener will be responsible for contacting the Hazard
Mitigation Advisory Committee members and organizing the annual meeting.
Committee members will be responsible for monitoring and evaluating the
progress of the mitigation strategies in the Plan.
Continued Public Involvement
The City of Santa Monica is dedicated to involving the publiC directly in the
continual review and updates of the Hazard Mitigation Plan. Copies of the
plan will be catalogued and made available at city hall and at all City
operated publiC libraries. The plan also includes the address and the phone
number of the City Planning Division, responsible for keeping track of publiC
comments on the Plan.
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DRAFT Santa Monica Hazard Mitigation Plan
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Section 1 - Mitigation Action Plan
1.1 Introduction
Emergencies and disasters cause death or leave people injured or displaced,
cause significant damage to our communities, businesses, public
infrastructure and our environment, and cost tremendous amounts in terms
of response and recovery dollars and economic loss.
Hazard mitigation reduces or eliminates losses of life and property. After
disasters, repairs and reconstruction are often completed in such a way as to
simply restore to pre-disaster conditions. Such efforts expedite a return to
normalcy; however, the replication of pre-disaster conditions results in a
cycle of damage, reconstruction, and repeated damage. Hazard mitigation
ensures that such cycles are broken and that post-disaster repairs and
reconstruction result in a reduction in hazard vulnerability.
While we cannot prevent disasters from happening, their effects can be
reduced or eliminated through a well-organized publiC education and
awareness effort, preparedness and mitigation. For those hazards which
cannot be fully mitigated, the community must be prepared to provide
efficient and effective response and recovery.
Why Develop a Mitigation Plan?
As the costs of damage from natural disasters continue to increase, the
community realizes the importance of identifying effective ways to reduce
vulnerability to disasters. Natural hazard mitigation plans assist communities
in reducing risk from natural hazards by identifying resources, information,
and strategies for risk reduction, while helping to gUide and coordinate
mitigation activities throughout the City of Santa Monica.
The plan provides a set of action items to reduce risk from natural hazards
through education and outreach programs and to foster the development of
partnerships, and implementation of preventative activities such as land use
programs that restrict and control development in areas subject to damage
from natural hazards.
The resources and information within the Mitigation Plan:
(1) Establish a basis for coordination and collaboration among
agencies and the publiC in City of Santa Monica;
(2) Identify and prioritize future mitigation projects; and
(3) Assist in meeting the requirements of federal assistance programs.
The mitigation plan works in conjunction with other City plans, including the
City General Plan and Emergency Operations Plans.
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Whom Does the Mitigation Plan Affect?
The City of Santa Monica's Natural Hazards Mitigation Plan affects entire city
and provides a framework for planning for natural hazards. The resources
and background information in the plan are applicable CitY-Wide, and the
goals and recommendations can lay groundwork for local mitigation plans
and partnerships.
Natural Hazard Land Use Policy in California
Planning for natural hazards should be an integral element of any city's land
use planning program. All California cities and counties have General Plans
and the implementing ordinances that are required to comply with the
statewide planning regulations.
The continuing challenge faced by local officials and state government is to
keep the network of local plans effective in responding to the changing
conditions and needs of California's diverse communities, particularly in light
of the very active seismic region in which we live.
This is particularly true in the case of planning for natural hazards where
communities must balance development pressures with detailed information
on the nature and extent of hazards.
Planning for Natural Hazards, calls for local plans to include inventories,
policies, and ordinances to gUide development in hazard areas. These
inventories should include the compendium of hazards facing the community,
the built environment at risk, the personal property that may be damaged by
hazard events, and most of all, the people who live in the shadow of these
hazards.
Support for Natural Hazard Mitigation
All mitigation is local, and the primary responsibility for development and
implementation of risk reduction strategies and policies lies with local
jurisdictions. Local jurisdictions, however, are not alone. Partners and
resources exist at the regional, state and federal levels. Numerous California
state agencies have a role in natural hazards and natural hazard mitigation.
Some of the key agencies include:
. The Governor's Office of Emergency Services (OES) is responsible for
disaster mitigation, preparedness, response, recovery, and the
administration of federal funds after a major disaster declaration;
. The Southern California Earthquake Center (SCEC) gathers information
about earthquakes, integrates this information on earthquake
10 DRAFT Santa Monica Hazard Mitigation
Plan
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phenomena, and communicates this to end-users and the general
public to increase earthquake awareness, reduce economic losses, and
save lives.
. The California Division of Forestry (CDF) is responsible for all aspects
of wildland fire protection on private, state, and administers forest
practices regulations, including landslide n1itigation, on non-federal
lands.
. The California Division of Mines and Geology (DMG) is responsible for
geologic hazard characterization, public education, the development of
partnerships aimed at reducing risk, and exceptions (based on science-
based refinement of tsunami inundation zone delineation) to state
mandated tsunami zone restrictions; and
. The California Division of Water Resources (DWR) plans, designs,
constructs, operates, and maintains the State Water Project; regulates
dams; provides flood protection and assists in emergency
management. It also educates the public, serves local water needs by
providing technical assistance
Plan Methodology
Information in the Mitigation Plan is based on research from a variety of
sources. Staff from the City of Santa Monica conducted data research and
analysis, facilitated steering committee meetings and public workshops, and
developed the final mitigation plan. The research methods and various
contributions to the plan include:
Past/On-going Mitigation Activities
Santa Monica Disaster Recovery Group
Since the 1994 Northridge earthquake, the City Of Santa Monica has worked
closely with FEMA and OES on several disaster recovery and hazard
mitigation projects. Resulting from damages sustained in the Northridge
earthquake, the City Of Santa Monica has received approximately $100
million dollars in disaster recovery and mitigation funds. These funds have
been applied to several projects throughout the City. These projects
i ncl uded:
. Extensive improvements to the City's sewer system
. Retrofitting of several parking structures throughout Santa
Monica
. The Miles Playhouse restoration project
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Plan
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The Disaster Recovery Group continues to meet regularly, and will be the
organization responsible for maintenance of the Local Hazard Mitigation Plan.
Throughout the development of the LHMP, members of the executive
planning committee attended staff meetings of several City Departments.
The purpose of these meetings was to 1) discuss the development of the
LHMP, 2) get input on potential mitigation actions, and 3) catalog past and
on-going mitigation steps in Santa Monica. Below is a table of such
mitigation actions.
n-gomg Mitigation Actions
MITIGATION STEPS
. Resolutions/Emergency Declarations
prepared ahead of time
. Deed restriction disclosure
. Litigation
. Subdivision regulation
. Tax incentives
. Transfer of development rights
. Media Strategy Working Group (PIT Crew)
. Disaster Recovery Office
. Smoke alarms
. Risk and vulnerability mapping
. Sprinklers
. Insurance/ disaster insurance
. Evacuation plans
. Evacuation routes
. Regular Evacuation Drills
. Internal Emergency Rosters
. Emergency shelters
Table 1.1 PastjO
DEPARTMENT
City Attorney
City Managers Office/
lSD/Risk Management
CCD/ Bayside District/
Civic Auditorium/ Comm.
Programs/ Cultural Affairs/
Human Services/ Open
Space Management
Clerk
EPWM/ Engineering&
Arch itectu ref
Environmental Programs/
Maintenance Management/
Solid Waste Management/
Utilities
. Document Storage
Civil Engineering & Architecture
. Routine publiC works inspections
. Palisades Bluffs Stabilization Effort
. Buffer spaces around buildings
. Erosion control landscaping
. Fire resistant landscaping
. Greenbelts
. Wildland management
. Windbreaks
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9/21/2004
. Hazardous materials container tie downs
Utilities
. Water Infrastructure Reliability study
. Adequate fire fighting water supply
. Capital improvement planning
. Debris catch basins
. Retention basins
. Storm drains
. Underground utility lies
. Proper signage for hazardous materials
. Minimal storage of flammable liquids
. Fire Extinguisher Checks
. Route restrictions
. Shelter in place education and training
. Site community warning systems
. Auxiliary power source
. Emergency water and sewer
. Coastal zone management
Finance
Fire/ Emergency . Disaster Assistance Response Training
Management . Regular briefings to the Executive Team
on Plan Refinement
. Emergency plans for critical facilities
. Emergency public information materials
. Emergency food and water
. Emergency communications
. Emergency operations plans
. Evacuation plans
. Evacuation routes
. Evacuation plans for special needs
populations
. Hazard analysis/ hazard information
systems
. Public education
. Resea rch
. Hazardous materials training/ enhanced
equipment
. Disaster Assistance Response Training
(DART) & Red Cross CPR! First Aid classes
. Sand sandbags those who live and work
in Santa Monica, to mitigate potential
flood damage.
. Public private partnerships
. Risk and vulnerability mapping
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. Staffing and training of Response
Personnel
Human Resources . Safety training for all employees
. Regular contract with EAP program
. Emergency contact forms
PCD/Building& Safety . Flood proofing
City . Building codes
Pia n ni ng/Tra nsportation/ . Building inspections
Traffic . Increased insulation
. Increased roof pitch
. Manufactured housing tie-downs
. Non-combustible building materials
. Roof bracing
. Roof sprinklers
. Structural connectors
. Better building design and engineering
. Better facility design
. Drainage systems
. Housing density
. Minimal roof overhang
. Proper egress
. Reduced use of glass
. Adequate roads w/ vehicular access
. Comprehensive planning and zoning
ordinances
Police . Evacuation Drills
. Site Security
Rent Control! Housing and . Routine residential and housing
Building i nspections/ citations/ etc.
. Seismic retrofit requirement
. City Ordinances
. Acquisition of property
. Building maintenance
14
Plan
DRAFT Santa Monica Hazard Mitigation
9/21/2004
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Input from the Steering Committee
The Hazard Mitigation Advisory Committee convened about every 6 to 8
weeks (a total of 8 meetings) to gUide development of the Mitigation Plan.
The committee played an integral role in developing the mission, goals, and
action items for the mitigation plan. The committee consisted of
representatives of public and private agencies and organizations in City of
Santa Monica, including:
City of Santa Monica Building and Safety
City of Santa Monica Fire Department
City of Santa Monica Finance
City of Santa Monica Police Department
City of Santa Monica Information Systems
City of Santa Monica GIS
City of Santa Monica Planning
City of Santa Monica Disaster Recovery Organization
City of Santa Monica Rent Control
City of Santa Monica Human Services Administration
City of Santa Monica Community and Cultural Services
City of Santa Monica City Manager's Office
City of Santa Monica Airport
City of Santa Monica City TV
Santa Monica Red Cross
Public Inclusion
City Of Santa Monica staff facilitated a number of opportunities for publiC
inclusion in the development of the plan, in order to gather input and ideas
from Santa Monica residents and stakeholders. Beginning with the City
Council meeting on September 9th, 2003, the Santa Monica community has
been invited to participate in the development of the LHMP. Since
September of 2003, the Santa Monica community has had numerous
opportunities to provide input on mitigation activities and priorities for
increasing the level of disaster preparedness and resilience.
Other opportunities for publiC involvement include:
. Airport Commission Meeting November 2003
. Santa Monica Red Cross Board Meeting March 2004
. Appearance on Santa Monica CityTV to publicize the Plan and request
publiC involvement. May 2004
. Section on the Mitigation Plan added to our Disaster Assistance
Response Team training. April 2004
. Staffed a booth at the Santa Monica Festival, the community's annual
gathering of sustainable living ideas and agencies. Distributed 300
flyers about the Mitigation Plan to attendees.
16 DRAFT Santa Monica Hazard Mitigation Plan
9/21/2004
. LHMP was discussed at monthly meetings of volunteer groups for the
Santa Monica Fire Department.
. Created and disseminated an Information Flyer about the LHMP
throughout the City. The flyer was also posted on the City's website
and listed a telephone and email contact for public input. Flyer was
also available at City Hal, Red Cross, Community Centers, Libraries,
and other locations throughout Santa Monica.
. An on-line survey was developed to assist the community in 1)
learning about the Plan, and 2) to offer input on priorities and action
items contained in the Plan. The survey is posted on the City's
homepage.
Table 1.3 Public Inclusion
Title Comment Date
Presentation on emergency
preparedness and the local hazard
Neighborhood Watch mitigation plan to a neighborhood
Group watch group of 20 attendees. 9/12/2004
Community and
Cultural Services Safety Public presentation of the LHMP to
Meeting local community group. 8/31/2004
EOC/ LHMP Team meeting. The Plan
is currently being reviewed by OES.
EOC/ LHMP Planning The group was updated on the Plan's
team meeting progress. 8/25/2004
Disaster Recovery Monthly DRO/ LHMP Executive
Organization/ LHMP Committee Meeting discussed the
Exec. Comm. Plan and the approval Process. 8/19/2004
LHMP was presented by Fire Chief
Jim Hone at the City-wide
Department Head Meeting. The
goals, objectives, and action items
Department Head were discussed, as well as the
Meetings process for the Plan's approval. 8/10/2004
Public Information Plan's progress was reported to the
Team Meeting Public Information Team. 8/9/2004
Conversation with OES Contact with Frank Hauck of OES to
for review of plan go over procedure for Plan review. 8/3/2004
Local Hazard Mitigation
Plan Executive Review of Plan by the Executive
Committee Planning Committee. 7/29/2004
Met with Fire Chief Met with Fire Chief Jim Hone to
regarding action items discuss action items re: public 7/28/2004
17
DRAFT Santa Monica Hazard Mitigation Plan
9/21/2004
awareness.
Discussion with Jory Wolf, Chief Info
Systems Officer for Santa Monica
Chief Information regarding development of alternate
Officer teleconference information systems in emergencies. 7/27/2004
Monthly meeting of airport volunteer
Meet with Emergency group. Mitigation Plan was
Volunteer Air Corps discussed. 7/21/2004
Met with students at the Los Angeles
Art Institute, in Santa Monica. The
Local Hazard Mitigation Plan will be
a project that a group of 6 students
will undertake, as a client/ student
endeavor. They will be tasked with
creating a publiC education/
awareness campaign regarding
emergency preparedness in Santa
Monica. They will produce a
Los Angeles Art campaign slogan, logo, posters, and
Institute web information. 7/19/2004
Monthly meeting of the City's publiC
information team. The Plan's
progress was discussed. Ideas for
Public Information increasing participation in online
Team Meeting survey were covered. 7/12/2004
Telephone discussion with Phil Watts
of Applied Fluids Engineering, a
tsunami engineering research firm.
We discussed the tsunami threat to
Telephone discussion Santa Monica and re-establishing
with Applied Fluids Eng. the tsunami-working group. 7/7/2004
Paul Weinberg met with Lt. of
Operations for the Santa Monica
Meeting with Lt. of Police Department to discuss the
Operations for SMPD LHMP. 6/29/2004
Meeting with Fire Chief/ Met with Fire Chief and Mayor
Mayor Richard Bloom Richard Bloom discussing the LHMP. 6/24/2004
Met with student assistant to work
Met with UCLA on Plan. Will collaborate with Center
Graduate Student for Disasters at UCLA School of
Assistant Public Health. 6/24/2004
Fire Department Chief LHMP was presented to the Fire
Officer's meeting Chiefs for discussion. 6/3/2004
18
DRAFT Santa Monica Hazard Mitigation Plan
9/21/2004
Local Hazard Mitigation Meeting of the Executive Committee
Plan Executive for the LHMP. Discussion of Goals
Committee and Action Items. 6/2/2004
Local Hazard Mitigation Meeting of the full working group of
Planning Committee the LHMP. Goals and Action Items
meeting were discussed. 5/26/2004
Meeting between Paul Weinberg and
Santa Monica Fire Chief Jim Hone.
The overall goals and action items
Meeting with Fire Chief for the Santa Monica Fire
Jim Hone Department were discussed. 5/22/2004
Kate Vernez and Paul Weinberg met
for one hour to discuss the next
steps and to prepare for upcoming
meeting with the entire planning
committee. The hiring of a Graduate
Student Intern was discussed and is
moving forward. The new goals and
action items were also discussed in
preparation for full committee
Co Chairs meeting meeting. 5/17/2004
Public Info Team meeting. List of
LHMP Public Info Team LHMP survey recipients was
Meeting developed. 5/11/2004
The Santa Monica Festival is an
annual event in town which focuses
on the environment and sustainable
living practices. Approximately
15,000 people attend the festival
throughout the day. Members of the
Local Hazard Mitigation Planning
Committee staffed a booth and
distributed approximately 1,000
flyers about the LHMP and disaster
Santa Monica Festival preparedness. 5/1/2004
Free Disaster Assistance Response
Training for those who live and work
DART Class Disaster in Santa Monica. This is an 8-hour
Assistance Response course. During the class, the LHMP
Training is discussed at length. 4/24/2004
Monthly meeting of earthquake
recovery group. This group has been
the steering committee for the
Earthquake Recovery LHMP. The next few months'
Group meeting strategy was discussed. 4/22/2004
19
DRAFT Santa Monica Hazard Mitigation Plan
9/21/2004
Co-Chair Paul Weinberg appears on
CITY TV local cable station. A six-
minute interview about the LHMP
Paul Weinberg appears and how the public can be involved.
on CITY TV to discuss This program will air daily for two
Plan weeks. 4/22/2004
Public Information Team meeting.
Monthly meeting of PIT Crew. LHMP
was discussed. The public education
survey for the LHMP was distributed
and team members were asked to
suggest community stakeholders to
participate in survey. The new LHMP
flyer was introduced. This flyer
describes the LHMP and will be
available throughout the City. The
Public Information LHMP information was also posted
Team Meeting on the City Website's homepage. 4/19/2004
Executive meeting between Paul
Weinberg and Kate Vernez to go
over the Plan's progress and set the
Co Chairs meeting strategy for the upcoming month. 4/15/2004
Paul Weinberg and Robin Gee met to
discuss this year's annual
"Employees Emergency
Preparedness Pledge Drive". We will
take the opportunity this year to
Meeting with CITY TV publicize the LHMP during the month
Director about Pledge of April as we implement the pledge
Drive drive. 3/29/2004
Disaster Recovery DRO is the steering committee for
Office Meeting the LHMP. 3/18/2004
Meeting with Lauren Meister of the
Insightlink Communication
Company. We discussed the
development of public information
survey to inform Santa Monica
residents, businesses, and
Meeting with Insightlink community organizations of the
Communications LHMP 3/18/2004
Staff meeting for Briefing the CCS on the LHMP
Community and requirements and exchanged
Cultural Services mitigation steps and ideas. 3/17/2004
Public Information PIT Crew discusses ways to publicize
Team Meeting the LHMP in Santa Monica. 3/15/2004
20
DRAFT Santa Monica Hazard Mitigation Plan
9/21/2004
Kate Vernez and Paul Weinberg
attended the Departmental Staff
meeting for the public works
department in Santa Monica. At this
meeting, a presentation was made
regarding the Plan. Ideas were
exchanged, and a draft "survey"
document was developed.
Paul Weinberg spoke at the Santa
Monica Red Cross chapter regarding
the Red Cross' role in the City's
emergency preparedness and
response plans. The development of
the local hazard mitigation plan was
discussed. A summary of existing
hazards in the City was covered, and
potential mitigation strategies were
Santa Monica Red Cross listed.
test/ training Vrisk Vrisk Training- Intro to website
The Disaster Recovery Group has
been addressing the LHMP since July
of 2004. This group is the main
Disaster Recovery planning committee behind the
Office Monthly Meeting LHMP team.
The first LHMP meeting of 2004 was
held in the council chambers. The
meeting re-affirmed the City's
commitment to completing the Plan
by the November 2004 deadline. In
the spirit of citywide involvement, a
guest speaker was invited to talk
about departmental cooperation.
Former Governor Michael Dukakis
spoke about publiC service and
cooperation. An outline of the LHMP
was distributed to all attendees.
There were close to 75 people in
attendance.
Public Information Team is
composed of City staff from each
Department and the Bayside District
agency. This group meets monthly
to discuss events in town and
methods of disseminating publiC
information. The LHMP was
discussed. We are working on a
Environmental and
Public Works Dpt. Staff
Meeting
Local Hazard Mitigation
Plan/ EOC Team
Meeting
PIT Crew Meeting
3/10/2004
3/8/2004
3/8/2004
2/19/2004
2/13/2004
2/9/2004
21
DRAFT Santa Monica Hazard Mitigation Plan
9/21/2004
survey for the PIT crew of how to
disseminate info regarding the
LHMP.
The PIT Crew in Santa Monica is the
Public Information Team, comprised
of City employees from several City
Departments, which meet monthly
to discuss events in Santa Monica,
and how the City involves the public.
The development of the Local
Hazard Mitigation Plan was
introduced at this meeting, and the
assistance of the PIT Crew in this
PIT Crew Meetings endeavor will be of use. 1/12/2004
Monthly Disaster Recovery Office
Disaster Recovery Meeting; Primary strategy for LHMP
Office Meeting is discussed 12/5/2003
The Santa Monica Fire Chief,
Administrative Captain and
Emergency Services Coordinator
made a presentation to the Santa
Monica Airport Commission. The
Emergency Services Coordinator
introduced the development of the
Local Hazard Mitigation Plan to the
commission and answered a number
of questions regarding the
Airport Commission development of the plan. 11/24/2003
The development of the Local
Hazard Mitigation Plan was approved
on consent at the City Council
Meeting. The staff report regarding
City Council Meeting on this consent action is posted on the
September 9, 2003 Santa Monica City homepage. 9/9/2003
The Fire Chief introduced the Plan
and it's requirements at the monthly
Department Head meeting. A
Department Head committee of City employees was
Meeting created following that meeting. 7/1/2003
Four members of the executive
hazard mitigation planning
OES Workshop on committee attended a workshop
Mitigation Plan held by CA OES detailing the
Requirements requirements of the Plan. 6/6/2003
22
DRAFT Santa Monica Hazard Mitigation Plan
9/21/2004
State and federal guidelines and requirements for mitigation plans:
Following are the Federal requirements for approval of a Natural Hazard
Mitigation Plan:
. Open public involvement, with public meetings that introduce the process
and project requirements.
. The public must be afforded opportunities for involvement in: identifying
and assessing risk, drafting a plan, and public involvement in approval
stages of the plan.
. Community cooperation, with opportunity for other local government
agencies, the business community, educational institutions, and non-
profits to participate in the process.
. Incorporation of local documents, including the local General Plan, the
Zoning Ordinance, the Building Codes, and other pertinent documents.
The following components must be part of the planning process:
. Complete documentation of the planning process
. A detailed risk assessment on hazard exposures in the community
. A comprehensive mitigation strategy, which describes the goals &
objectives, including proposed strategies, programs & actions to avoid
long-term vulnerabilities.
. A plan maintenance process, which describes the method and schedule of
monitoring, evaluating and updating the plan and integration of the All
Hazard Mitigation Plan into other planning mechanisms.
. Formal adoption by the City Council.
. Plan Review by both State OES and FEMA
These requirements are spelled out in greater detail in the following plan
sections and supporting documentation.
City of Santa Monica staff examined existing mitigation plans from around
the country, current FEMA hazard mitigation planning standards (386 series)
and the State of California Natural Hazards Mitigation Plan Guidance.
Other reference materials consisted of county and city mitigation plans,
including:
Clackamas County (Oregon) Natural Hazards Mitigation Plan
Six County (Utah) Association of Governments
Upper Arkansas Area Risk Assessment and Hazard Mitigation Plan
Urbandale-Polk County, Iowa Plan
Hamilton County, Ohio Plan
Natural Hazard Planning Guidebook from Butler County, Ohio
City of Austin, Hazard Mitigation Plan
Hazard specific research: City of Santa Monica staff collected data and
compiled research on six hazards: earthquakes, landslides, flooding,
23
DRAFT Santa Monica Hazard Mitigation Plan
9/21/2004
tsunamis, wildfires and severe windstorms/thunderstorms. Research
materials came from state agencies including OES, and CDF. The City of
Santa Monica staff conducted research by referencing historical local
newspapers, interviewing long time residents, long time City of Santa Monica
employees and locating City of Santa Monica information in historical
documents. The City of Santa Monica staff identified current mitigation
activities, resources and programs, and potential action items from research
materials and stakeholder interviews.
The Local Hazard Mitigation Planning Committee hired a Graduate Student
Intern from the UCLA School of Public Policy, to assist with the Plan. This
Graduate Student worked closely with the Center For Disaster Studies at the
Graduate School of Public Health at UCLA, in developing the Plan. Extensive
research and interviews were conducted with the Center for Disaster Studies
at UCLA in creating the Local Hazard Mitigation Plan.
Public Involvement
The City of Santa Monica has been publicizing the creation of the Local
Hazard Mitigation Plan since the summer of 2003. The creation of the Plan
was approved by City Council in September of 2003. An information flyer
was created and disseminated throughout town, requesting publiC
participation. City of Santa Monica staff administered a web-based survey to
generate publiC input into the plan. The survey will proVide a valuable
resource in generating community input for the Plan. The survey will also
assist us in addressing the natural hazard concerns of people who live and
work in Santa Monica.
The resources and information cited in the mitigation plan proVide a strong
local perspective and help identify strategies and activities to make City of
Santa Monica more disaster resilient.
How Is the Plan Used?
Each section of the mitigation plan proVides information and resources to
assist people in understanding the City and the hazard-related issues facing
citizens, businesses, and the environment. Combined, the sections of the
plan work together to create a document that gUides the mission to reduce
risk and prevent loss from future natural hazard events.
The structure of the plan enables people to use a section of interest to them.
It also allows City government to review and update sections when new data
becomes available. The ability to update individual sections of the mitigation
plan places less of a financial burden on the City. Decision-makers can
allocate funding and staff resources to selected pieces in need of review,
thereby avoiding a full update, which can be costly and time-consuming.
New data can be easily incorporated, resulting in a natural hazards mitigation
24
DRAFT Santa Monica Hazard Mitigation Plan
9/21/2004
plan that remains current and relevant to City of Santa Monica.
The mitigation plan is organized in three sections. Section 1 contains an
executive summary, introduction, City profile, risk assessment, mitigation
goals and action items, and plan maintenance. Section 2 contains the six
natural hazard sections and Section 3 includes the appendices. Each section
of the plan is described below.
Section 1 - Mitigation Action Plan
Executive Summary: Five-Year Action Plan
The Five-Year Action Plan proVides an overview of the mitigation plan
mission, goals, and action items. The plan action items are included in
this section, and address multi-hazard issues, as well as activities that
can be implemented to reduce risk and prevent loss from future
natural hazard events.
1.1 Introduction
The Introduction describes the background and purpose of developing
the mitigation plan for City of Santa Monica.
1.2 Community Profile
This section presents the history, geography, demographics, and
socioeconomics of City of Santa Monica. It serves as a tool to proVide
an historical perspective of natural hazards in the City.
1.3 Risk Assessment
This section proVides information on hazard identification, vulnerability
and risk associated with natural hazards in City of Santa Monica.
1.4 Mitigation Goals
This section proVides information on the process used to develop goals
that cut across the five natural hazards addressed in the mitigation
plan.
1.5 Mitigation Action Items
This section proVides information on the action items that cut across
the five natural hazards addressed in the mitigation plan.
1.6 Plan Maintenance
25 DRAFT Santa Monica Hazard Mitigation Plan
9/21/2004
This section provides information on plan implementation, monitoring
and evaluation.
Section 2 - Hazard Specific Information
Hazard-Specific Information on the five chronic hazards are addressed in this
plan. Chronic hazards occur with some regularity and may be predicted
through historic evidence and scientific methods. The chronic hazards
addressed in the plan include:
2.1
2.2
2.3
2.4
2.5
2.6
Earthquake
Landslide
Flooding
Tsunami
Wildfires
Severe Windstorm/Thunderstorm
Catastrophic hazards do not occur with the frequency of chronic hazards, but
can have devastating impacts on life, property, and the environment. In
Southern California, because of the geology and terrain, earthquake,
landslides, and flooding also have the potential to be catastrophic as well as
chronic hazards. For the coastal areas of Southern California, tsunamis,
while very rare, have the potential to calamitously devastate low-lying
coastal areas.
Each of the hazard-specific sections includes information on the history,
hazard causes and characteristics, hazard assessment, goals and action
items, and local, state, and national resources.
Section 3 - Resources
The plan appendices are designed to provide users of the City of Santa
Monica's Natural Hazards Mitigation Plan with additional information to assist
them in understanding the contents of the mitigation plan, and potential
resources to assist them with implementation.
Appendix A: Plan Resource Directory
The resource directory includes City, regional, state, and national
resources and programs that may be of technical and/or financial
assistance to City of Santa Monica during plan implementation.
Appendix B: Public Participation Process
This appendiX includes specific information on the various publiC
processes used during development of the plan.
26
DRAFT Santa Monica Hazard Mitigation Plan
9/21/2004
Appendix C: Benefit Cost Analysis
This section describes FEMA's requirements for benefit cost analysis in
natural hazards mitigation, as well as various approaches for
conducting economic analysis of proposed mitigation activities.
Appendix D: List of Acronyms
This section proVides a list of acronyms for City, regional, state, and
federal agencies and organizations that may be referred to within the
City of Santa Monica's Natural Hazards Mitigation Plan.
Appendix E: Glossary
This section proVides a glossary of terms used throughout the plan.
1.2 Community Profile
The section is to proVide a broad perspective, brief history and describes the
makeup and development of the community.
Topography
Located along the Westside of Los Angeles County, the City of Santa Monica
is comprised of 8.3 square miles and is boarded on three sides by the City of
Los Angeles and the Pacific Ocean on the west. Santa Monica occupies a
central position along the arching shoreline of Santa Monica Bay. The beach,
which has grown through accretion, is several hundred feet wide-one of the
widest stretches of beach in this part of southern California.
Santa Monica sits atop a coastal plain that is defined on its northern
boundary by Santa Monica Canyon. This deep arroyo attracted native
American settlements and then the area's first European settlement in the
1860s-a summer colony for residents of the new City of Los Angeles some
twelve miles inland along the foot of the mountains. South of the canyon, the
rugged terrain gives way to the gently south sloping upland of the City's
north side. The land descends to a historic drainage channel that ran west to
the sea along the general line of the present-day Santa Monica freeway. This
drainage formed a distinctive draw that originally marked the edge of the
Palisades and defined the City's southerly border. It is this collision of this
south sloping upland with the southwesterly trending coastline that creates
the City's most memorable topographic feature-the Palisades-a sheer cliff
of fragile sandstone that rises about 100 feet above the coast that separates
the northern portion of the City from the beach below.
The topography of the City's south side is considerably more complex. The
27
DRAFT Santa Monica Hazard Mitigation Plan
9/21/2004
broad upland occupied by the Sunset Park neighborhood rolls off gradually to
the east and descends to the west into a series of parallel ridges that roll
gently down into Ocean Park beach. To the south, it drops toward the
historical coastal wetland of Ballona Creek. The landscape at the center of
the City reflects the historic patterns created by water as it flowed from
inland areas to the bay.
Climate
The climate in Santa Monica is temperate throughout the year. Average high
temperatures vary between 650F/18C to 720F/22C from winter to summer.
Summers are mild and dry, and winters are cool, with an annual average of
16 inches of precipitation.
Population/Demographics
According to the 2000 Census, Santa Monica's population is 84,084, or about
10,100 persons per square mile. Additional housing units added through
June, 2002, have brought the population to around 85,686.
Senior citizens (65 years and over) comprise 14% of the city's population,
and nearly half (42%) of them reported having at least one disability in
2000. Although it is home to a significant number of older people, Santa
Monica is a city whose age distribution shows a significant concentration in
the 22-44 age group, and has fewer youth under 19 years of age (16%) than
the county average. The average Santa Monica resident is 39 years of age.
According to the 1999 City of Santa Monica Homeless Population Survey, an
estimated 1,037 individuals are homeless, with 72% of them being males,
and 2% of the homeless being under the age of 17.
Santa Monica is unique in its household and housing cross-section. 38% of
the households in Santa Monica are families, and 62% are non-family
households, the reverse of the national average of 68% families and 32%
non-family households. There are an average of 2.8 persons per family, and
1.8 persons per household. The 49,065 housing units in the City as of 2003
are primarily (70 %) occupied by renters as opposed to homeowners, again
the reverse of the national average of 34% renters and 66% homeowners.
The highest geographic concentration (28%) of households that are families
with children in 2000 was in the 90402 zip code area.
The educational attainment levels of Santa Monica residents were, on
average, significantly higher than for Los Angeles County and California in
2000. According to the 2000 Census, 61 % of residents over the age of 25
reported having a college degree, (e.g. either an Associates degree or
higher). This figure is relatively high when compared to Los Angeles County
with 30% and California with 34% of the 25 and over population having
college degrees.
The median household income in Santa Monica is $50,714 as of the 2000
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Census. The number of households earning over $150,000 doubled between
1990 and 2000 when it reached 12% of total households. 60% of Santa
Monica's employed population are employed as management, professional,
and related occupations. The most popular employment industries for Santa
Monica residents were educational, health & social service (18.8%), followed
closely by professional, scientific & management industries (18.6%).
Information services provided employment for 14.6% of residents.
Economy
Santa Monica is an economically successful city with about 16,000 businesses
which collectively generate almost $8.4 billion in gross annual income. About
$2.3 billion of these sales are in the retail sector. There are an estimated
71,000 jobs in Santa Monica, generating a combined payroll of around $3
billion. The Westside, including Santa Monica, also has a large resident
workforce of skilled "knowledge workers". Over 60% of the 47,059 employed
Santa Monica residents work in managerial, professional, and related
occupations.
Industry
Whereas the smallest businesses remain larger in number, the most jobs are
proVided by the mid-sized companies in Santa Monica. Taxable sales for the
City of Santa Monica reflect the general health of the business community,
particularly the retail community, and are a substantial source of revenues
for the City. Of the three top economic categories, New Car Sales contributed
18.4%, Restaurants contributed 14.7%, and Apparel 10.4% of the $23.2
million the City earned in from taxable retail in 2001.
Tourism is a key component of the economy and lifestyle of this beachfront
community. Over 3.8 million people visit the city each year from outside Los
Angeles County for pleasure, vacation, or business. These visitors spend
$788 million annually, and bring in hotel tax revenues of $20 million to the
city. Approximately 11,500 jobs are supported by the tourist industry. Even
with the recent slowdown in the tourism industry, the City's hotel occupancy
rate in its 3,500 rooms remains good, at 73%. The city is an international
destination, as well as the destination for millions of day-trippers, particularly
on weekends, as they throng to our clean beaches, and visit our Pier and
special retail destinations such as the Third Street Promenade, Main Street,
Montana Avenue, and Santa Monica Place.
Development History
Oversight of construction and development activities as well as long-range
planning for Santa Monica is proVided by the City's Department of Planning
and Community Development (PCD). The City's long-range planning,
development and growth policies are set forth in the General Plan, which
contains the following 7 elements: Land Use, Circulation, Open Space,
Conservation, Housing, Safety, and Noise. For certain regions of the city,
Specific Plans have been developed which specify development and growth
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DRAFT Santa Monica Hazard Mitigation Plan
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policies for each region. The Specific Plans and the Elements of the General
Plan are described in more detail in Policies and Ordinances.
Plans for all proposed construction and development projects in Santa Monica
must be first submitted to the PCD's Building and Safety Division for review.
Building and Safety plan checkers verify that proposed projects comply with
the Uniform Building Code, the City Municipal Code, State Title 24
requirements, and the Americans with Disabilities Act (ADA) requirements.
Depending on the scope and nature of the project, the plans may be
forwarded to the Planning and Zoning Division for further review prior to
issuance of building permits. The PCD's Planning and Zoning Division is
responsible for interpreting the Zoning Ordinance as well as processing
development and subdivision applications, forwarding plans to the
appropriate commissions or boards for review, assuring project compliance
with the California Environmental Quality Act (CEQA), conducting design
review of proposed buildings and proVide staffing assistance to the Planning
Commission, the Architectural Review Board, the Landmarks Commission and
the Zoning Administrator. These commissions and boards make
determinations on a variety of planning and development issues and are
briefly described below:
Planning Commission - A seven member panel appointed by City Council
to four year terms. The Commission meets twice monthly to review requests
for development permits, conditional use permits, appeals to Zoning
Administrator decisions, and planning poliCY matters. The Commission
conducts publiC hearings on most of its agenda items. Within each zoning
district there is a specific square footage threshold for development review.
The Planning Commission reviews projects exceeding these thresholds as
well as projects that require conditional use permits. Planning Commission
decisions can be appealed to the City Council.
Architectural Review Board - A seven member panel appointed by City
Council to four year terms. The ARB is required to include at least two
registered profeSSional architects as well as persons with expertise in
conservation, recreation, design, landscaping, the arts, urban planning,
cultural-historical preservation, and ecological and environmental sciences.
The board meets twice monthly to review the exterior design of all buildings
(except single family residences), signs and landscaping. The board was
formed to ensure that new development upholds the appearance of the
community and reviews proposed projects to ensure that they are compatible
with the neighborhood and in compliance with landscaping and sign
requirements. ARB decisions can be appealed to the City Council.
landmarks Commission - A seven member panel appointed by City
Council. Commission members include a registered architect, a local
historian, an architectural historian, and a California-licensed real estate
agent. The commission meets monthly and is charged with the task of
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designating buildings in the city as historic landmarks, designating historic
districts and updating the city's historic resources inventory. Landmarks
Commission decisions can be appealed to the City Council.
Zoning Administrator - The Zoning Administrator is a PCD staff member
and has the authority to rule on various zoning matters such as
administrative approvals, temporary use permits, performance standards
permits, variances, use permits, and reduced parking permits. Discretionary
Zoning Administrator decisions can be appealed to the Planning Commission.
Municipal construction and development projects are overseen by the
Engineering Division of the Department of Environmental and Public Works
Management. All municipal projects are subject to the same plan check
process and requirements as private development.
Future Development
The City of Santa Monica recognizes that we live in a period of great
environmental crisis. As a community, we need to create the basis for a more
sustainable way of life both locally and globally through the safeguarding and
enhancing of our resources and by preventing harm to the natural
environment and human health. We are resolved that our impact on the
natural environment must not jeopardize the prospects of future generations.
In 1994, the City Of Santa Monica adopted the Sustainable City Program and
in 2003, the Sustainable City Plan was fully adopted.
Elements of the Sustainable City Program include:
Community and Economic Development
Construction and Development
Education
Energy
Hazardous Materials
Housi ng
Purchasing
Solid Waste
Stormwater & Wastewater
Transportation
Water
Community Goals (adopted February 11, 2003):
Resource Management
Environmental & Public Health
Transportation
Economic Development
Open Space & Land Use
Housi ng
Community Education & Civic Participation
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1.3 Risk Assessment
What is a Risk Assessment?
Conducting a risk assessment can provide information: on the location of
hazards, the value of existing land and property in hazard locations, and an
analysis of risk to life, property, and the environment that may result from
natural hazard events. Specifically, the three levels of a risk assessment are
as follows:
1) Hazard Identification
This is the description of the geographic extent, potential intensity and the
probability of occurrence of a given hazard. Maps are frequently used to
display hazard identification data. The City of Santa Monica identified six
major hazards that affect this geographic area. These hazards -
earthquakes, landslides, flooding, tsunamis, wildfires and severe
windstorms/thunderstorms - were identified through an extensive process
that utilized input from the Hazard Mitigation Advisory Committee. The
geographic extent of each of the identified hazards has been identified by the
City of Santa Monica GIS department using the best available data.
2) Profiling Hazard Events
This process describes the causes and characteristics of each hazard, how it
has affected City of Santa Monica in the past, and what part of the City of
Santa Monica's population, infrastructure, and environment has historically
been vulnerable to each specific hazard. A profile of each hazard discussed
in this plan is provided in each hazard section. For a full description of the
history of hazard specific events, please see the appropriate hazard chapter.
3) Vulnerability Assessment/Inventorying Assets
This is a combination of hazard identification with an inventory of the existing
(or planned) property development(s) and population(s) exposed to a
hazard. Critical facilities are of particular concern because these entities
proVide essential products and services to the general publiC that are
necessary to preserve the welfare and quality of life in the City and fulfill
important publiC safety, emergency response, and/or disaster recovery
functions. The critical facilities have been identified and are listed in Table
1.1 at the end of this section. A description of the critical facilities in the City
is also proVided in this section. In addition, this plan includes a community
issues summary in each hazard section to identify the most vulnerable and
problematic areas in the City, including critical facilities, and other publiC and
private property.
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DRAFT Santa Monica Hazard Mitigation Plan
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4) Risk Analysis
Estimating potential losses involves assessing the damage, injuries, and
financial costs likely to be sustained in a geographic area over a given period
of time. This level of analysis involves using mathematical models. The two
measurable components of risk analysis are magnitude of the harm that may
result and the likelihood of the harm occurring. Describing vulnerability in
terms of dollar losses provides the community and the state with a common
framework in which to measure the effects of hazards on assets. For each
hazard where data was available, quantitative estimates for potential losses
are included in the hazard assessment.
5) Assessing Vulnerability/Analyzing Development Trends
This step provides a general description of land uses and development trends
within the community so that mitigation options can be considered in land
use planning and future land use decisions. This plan provides
comprehensive description of the character of City of Santa Monica in the
Community Profile. This description includes the geography and
environment, population and demographics, land use and development,
housing and community development, employment and industry, and
transportation and commuting patterns. Analyzing these components of City
of Santa Monica can help in identifying potential problem areas, and can
serve as a gUide for incorporating the goals and ideas contained in this
mitigation plan into other community development plans.
Hazard assessments are subject to the availability of hazard-specific data.
Gathering data for a hazard assessment requires a commitment of resources
on the part of participating organizations and agencies. Each hazard-specific
section of the plan includes a section on hazard identification using data and
information from City, County or State agency sources.
Regardless of the data available for hazard assessments, there are numerous
strategies the City can take to reduce risk. These strategies are described in
the action items detailed in each hazard section of this Plan. Mitigation
strategies can further reduce disruption to critical services, reduce the risk to
human life, and alleviate damage to personal and publiC property and
infrastructure. Action items throughout the hazard sections provide
recommendations to collect further data to map hazard locations and conduct
hazard assessments.
Federal Requirements for Risk Assessment
Recent federal regulations for hazard mitigation plans outlined in 44 CFR Part
201 include a requirement for risk assessment. This risk assessment
requirement is intended to provide information that will help communities to
identify and prioritize mitigation activities that will reduce losses from the
identified hazards. There are five hazards profiled in the mitigation plan,
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DRAFT Santa Monica Hazard Mitigation Plan
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including earthquakes, landslides, flooding, tsunamis, and severe
windstorms/thunderstorms. The Federal criteria for risk assessment and
information on how the City of Santa Monica's Natural Hazard Mitigation Plan
meets those criteria is outlined in Table 3-2 below.
Table 1.4 Federal Criteria for Risk Assessment
Section 322 Plan
Requirement
Identifying Hazards
Profiling Hazard Events
Assessing Vulnerability:
Identifying Assets
Assessing Vulnerability:
Estimating Potential
Losses:
Assessing Vulnerability:
Analyzing Development
Trends
How is this addressed?
Each hazard section includes an inventory of
the best available data sources that identify
hazard areas. To the extent GIS data are
available, the City developed maps identifying
the location of the hazard in the City. The
Executive Summary and the Risk Assessment
sections of the plan include a list of the hazard
maps.
Each hazard section includes documentation of
the history, and causes and characteristics of
the hazard in the City.
Where data is available, the vulnerability
assessment for each hazard addressed in the
mitigation plan includes an inventory of all
publicly owned land within hazardous areas.
Each hazard section provides information on
vulnerable areas in the City in the Community
Issues section. Each hazard section also
identifies potential mitigation strategies.
The Risk Assessment Section of this mitigation
plan identifies key critical facilities and lifelines
in the City and includes a map of these
facilities. Vulnerability assessments have been
completed for the hazards addressed in the
plan, and quantitative estimates were made for
each hazard where data was available.
The City of Santa Monica Profile Section of this
plan provides a description of the development
trends in the City, including the geography and
environment, population and demographics,
land use and development, housing and
community development, employment and
industry, and transportation and commuting
patterns.
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DRAFT Santa Monica Hazard Mitigation Plan
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Critical Facilities and Infrastructure
Facilities critical to government response and recovery activities (i.e., life
safety and property and environmental protection) include: 911 centers,
emergency operations centers, police and fire stations, publiC works facilities,
communications centers, sewer and water facilities, hospitals, bridges and
roads, shelters, and shelters, Facilities that, if damaged, could cause serious
secondary impacts may also be considered "critical." A hazardous material
facility is one example of this type of critical facility.
Critical and essential facilities are those facilities that are vital to the
continued delivery of key government services or that may significantly
impact the public's ability to recover from the emergency. These facilities
may include: buildings such as the jail, law enforcement center, publiC
services building, community corrections center, the courthouse, and juvenile
services building and other publiC facilities such as schools. Table 1.2 lists
the critical facilities.
Summary
Natural hazard mitigation strategies can reduce the impacts concentrated at
large employment and industrial centers, publiC infrastructure, and critical
facilities. Natural hazard mitigation for industries and employers may include
developing relationships with emergency management services and their
employees before disaster strikes, and establishing mitigation strategies
together. Collaboration among the publiC and private sector to create
mitigation plans and actions can reduce the impacts of natural hazards.
1.4 Mitigation Goals
Explanation:
The community's hazard reduction goals, as reflected
in the plan, along with their corresponding objectives,
gUide the development and implementation of
mitigation measures. This section should describe
what these goals are and how they were developed.
The goals could be developed early in the planning
35
DRAFT Santa Monica Hazard Mitigation Plan
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process and refined based on the risk assessment
findings, or developed entirely after the risk
assessment is completed. They should also be
compatible with the goals of the community as
expressed in other community plan documents.
Although the Rule language does not require a
description of objectives, communities are highly
encouraged to include a description of the objectives
developed to achieve the goals so that reviewers
understand the connection between goals, objectives,
and activities. The goals and objectives should: - Be
based on the findings of the local and State risk
assessments; and - Represent a long-term vision for
hazard reduction or enhancement of mitigation
capabilities.
The following section provides an overview of the Mitigation Goals and
Objectives:
Goal #1: Increase Public Awareness of Local Hazards
Description: Increase public awareness and understanding, support,
and demand for hazard mitigation.
Objectives:
. Heighten public awareness of the full range of natural hazards
they may face.
. Educate the public on actions they can take to prevent or reduce
the loss of life and/or property from all hazards.
. Publicize and encourage the adoption of appropriate hazard
mitigation measures.
Goal #2: Protection of Lives and Property
Description: Implement activities that assist in protecting lives by
making homes, businesses, infrastructure, critical facilities, and other
property more resistant to natural hazards.
Objectives:
. Advise public about health and safety precautions to protect
from injury and loss.
. Assess the feasibility of warning and communication
technologies to mitigate damage from natural hazards.
. Reduce damage to enhance protection of dangerous areas
during hazardous events.
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DRAFT Santa Monica Hazard Mitigation Plan
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. Protect critical facilities and services.
. Ensure Emergency Services and critical facilities are included in
mitigation strategies.
Goal #3: Promote Sustainable Living
Description: Promote development in a sustainable manner.
Objectives:
. Incorporate hazard mitigation into long-range planning and
development activities.
. Promote beneficial use of hazardous areas while expanding open
space and recreational opportunities.
. Utilize regulatory approaches to prevent creation of future
hazards to life and property.
Goal #4: Partnerships and Implementation
Description: Build and support local partnerships to continuously
become less vulnerable to natural hazards.
Objectives:
. Build and support local partnerships with stakeholders in the
community.
. Build a cadre of committed volunteers to safeguard the
community before, during, and after a disaster.
. Build hazard mitigation concerns into City planning and
budgeting process.
Goal #5: Strengthen Emergency Services Capability
Description: Establish policies and procedures to ensure mitigation
projects for critical facilities, services, and infrastructure.
Objectives:
. Provide training to City departments and non-City entities on
mitigation programs and techniques that could be incorporated
into a variety of projects.
Strengthen emergency operations by increasing collaboration and
coordination among public agencies, non-profit organizations, business, and
industry.
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DRAFT Santa Monica Hazard Mitigation Plan
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1.5 Mitigation Actions/Projects
Explanation:
The local jurisdiction should list potential loss
reduction activities it has identified in its planning
process and describe its approach to evaluating these
activities to select those that achieve the community's
goals and objectives. Particular attention should be
given to those mitigation activities that address
existing and new buildings and infrastructure. Not all
of the mitigation measures identified may ultimately
be included in the community's plan due to
prohibitive costs, scale, low benefit/cost analysis
ratios, or other concerns. The process by which the
community decides on particular mitigation measures
must be described. The information will also be
valuable as part of the alternative analysis for the
National Environmental Policy Act (NEPA) review
required if projects are federally funded.
This section serves to identify proposed projects in the community.
1. Identify Future Mitigation Projects and Potential Funding Sources
Description: Identify and pursue potential projects and funding sources to
develop and implement local and county mitigation activities.
. Develop incentives to pursue mitigation projects
. Allocate resources to assist in mitigation projects when pOSSible
. Partner with other organizations and agencies to identify grant
programs and foundations that support mitigation activities
. Identify funds to improve the seismic performance of the sewer
system at the 4th Street overpass
. Identify funds for City Yards improvement projects
. Identify funds for bluff mitigation projects
Priority: High
Responsible Organization: Planning & Community Development,
Finance, Fire, EPWM Departments
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DRAFT Santa Monica Hazard Mitigation Plan
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Status: On-going
Timeline: Long-Term
Cost: TBA
Potential Funding Sources: Grants
Plan Goals Addressed: Protection of Lives and Property
Partnerships for Implementation
Emergency Services Capability
2.lntegrate LHMP into Existing Programs, Ordinances, Building Codes
Description: Integrate the goals and action items from the Local Hazard
Mitigation Plan into existing regulatory documents and programs, including
local ordinances and building codes, where appropriate. Assess feasibility of
gas shut-off valve ordinance as required by other regional jurisdictions.
(Based on 300+ gas leaks following the Northridge earthquake.)
Priority: Open
Responsible Organization: Planning & Community Development
Status: Proposed
Timeline: Long-Term
Cost: TBA
Potential Funding Sources: General Funds, Grants
Plan Goals Addressed: Promote Sustainable Living
Partnerships for Implementation
3. Critical Information Systems
Description: Design and implement a protection program for the critical
information systems infrastructure, including telephones, computers, radio,
911 services, information systems, and backup systems.
. Continue to assess and improve radio interoperability between City
departments, agencies and neighboring jurisdictions
. Enhance GIS response capability in emergencies, including building
data inventory, damage assessment and evacuation planning
Priority:
Responsi ble Orga n ization:
Status:
Timeline:
Cost:
Potential Funding Sources:
Plan Goals Addressed:
High
Information Systems Division
Proposed
Long- Term
TBA
General Funds, Grants
Emergency Services Capability
Protection of Lives and Property
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DRAFT Santa Monica Hazard Mitigation Plan
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4. Increase Public Awareness of Hazards and Disaster Preparedness
Description: Design and implement a comprehensive campaign of public
awareness of local natural hazards and disaster preparedness techniques,
using media, print, radio, Internet, lecture and hands-on training.
. Design and develop publiC education campaign for emergency
preparedness and hazard mitigation for those who live and work in
Santa Monica
. Assess the feaSibility of establishing Fire Captain training position to
augment publiC education efforts of the Police Community Relations,
City Manager Office's Public Information, Fire Department and
Community Cultural Services groups
. Re-establish publiC education in schools and the community
. Increase the number of Disaster Assistance Response Training (DART)
classes for those who live and work in Santa Monica
. Expand Automated External Defribulator program
Priority: High
Responsible Organization: Fire Department
Status: On-going
Timeline: Long-Term
Cost: TBA
Potential Funding Sources: General Funds, Grants
Plan Goals Addressed: Increase Public Awareness
Emergency Services Capability
Protection of Lives and Property
5. Strengthen Evacuation Plans for City Facilities
Description: Continue to strengthen and develop evacuation plans, policies
and procedures for City facilities located throughout Santa Monica.
. Modify evacuation plans to incorporate City Public Safety agencies
. Train employees and practice City facility evacuation plans with
participation by City Public Safety agencies such as Police and Fire
Priority:
Responsible Organization:
Status:
Timeline:
Cost:
Potential Funding Sources:
Plan Goals Addressed:
Open
Risk Management, Fire Department
On-going
On-going
TBA
General Funds, Grants
Protection of Lives and Property
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DRAFT Santa Monica Hazard Mitigation Plan
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6. Public Alert and Notification
Description: Assess feasibility of a public alert and notification system for
disasters.
. Enhance notification procedures of key city staff to respond to
emergencies
. Re-establish Tsunami Working Group
. Continue to study technological advances in capabilities and advances
in public alert warning systems
Priority:
Responsible Organization:
Status:
Timeline:
Cost:
Potential Funding Sources:
Plan Goals Addressed:
Open
Police, Fire Departments
Proposed
Long-term
TBA
General Funds, Grants
Protection of Lives and Property
Emergency Services Capability
41
DRAFT Santa Monica Hazard Mitigation Plan
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1.6 Plan Maintenance
The plan maintenance section of this document details the formal process
that will ensure that the City of Santa Monica's Natural Hazards Mitigation
Plan remains an active and relevant document. The plan maintenance
process includes a schedule for monitoring and evaluating the Plan annually
and producing a plan revision every five years. This section describes how
the city will integrate public participation throughout the plan maintenance
process. Finally, this section includes an explanation of how the City of
Santa Monica's government intends to incorporate the mitigation strategies
outlined in this Plan into existing planning mechanisms such as the City
General Plan, Capital Improvement Plans, and Building and Safety Codes.
MONITORING AND IMPLEMENTING THE PLAN
Plan Adoption
The City Council will be responsible for adopting the City of Santa Monica's
Natural Hazards Mitigation Plan. This governing body has the authority to
promote sound publiC poliCY regarding natural hazards. Once the plan has
been adopted, the City's Emergency Services Coordinator will be responsible
for submitting it to the State Hazard Mitigation Officer to the Governor's
Office of Emergency Services. The Governor's Office of Emergency Services
will then submit the plan to the Federal Emergency Management Agency
(FEMA) for review. This review will address the federal criteria outlined in
FEMA Interim Final Rule 44 CFR Part 201. Upon acceptance by FEMA, the
City of Santa Monica will gain eligibility for Hazard Mitigation Grant Program
funds.
Coordinating Body
A City of Santa Monica's Hazard Mitigation Committee will be responsible for
coordinating implementation of plan action items and undertaking the formal
review process. The City Council will assign representatives from city
agencies, including, but not limited to, the current Hazard Mitigation Advisory
Committee members. The city has formed a Hazard Mitigation Committee
that consists of members from local agencies, organizations, and citizens,
and includes the following:
City of Santa Monica Building and Safety
City of Santa Monica Fire Department
City of Santa Monica Finance
City of Santa Monica Police Department
City of Santa Monica Information Systems
City of Santa Monica GIS
City of Santa Monica Planning
City of Santa Monica Disaster Recovery Organization
City of Santa Monica Rent Control
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City of Santa Monica Human Services Administration
City of Santa Monica Community and Cultural Services
City of Santa Monica City Manager's Office
City of Santa Monica Airport
City of Santa Monica City TV
Santa Monica Red Cross
California Division of Mines and Geology
Federal Emergency Management Agency
The Governor's Office of Emergency Services
In order to make this committee as broad and useful as possible, the City
Administrator will engage other relevant organizations and agencies in
hazard mitigation. The recommendations for adding to the Hazard Mitigation
Advisory Committee include:
An elected official
A representative from the Chamber of Commerce
An insurance company representative
Community Planning Organization representatives
A representative from the City Manager's office
Representation from profeSSional organizations such as the Home
Builders Association
A representative from the South Bay Council of Governments
The Hazard Mitigation Advisory Committee will meet no less than bi-annually.
Meeting dates will be scheduled once the final Hazard Mitigation Advisory
Committee has been established. These meetings will provide an opportunity
to discuss the progress of the action items and maintain the partnerships
that are essential for the sustainability of the mitigation plan.
Convener
The City Council will adopt the City of Santa Monica's Natural Hazard
Mitigation Plan, and the Hazard Mitigation Advisory Committee will take
responsibility for plan implementation. The City Manager will serve as a
convener to facilitate the Hazard Mitigation Advisory Committee meetings,
and will assign tasks such as updating and presenting the Plan to the
members of the committee. Plan implementation and evaluation will be a
shared responsibility among all of the Natural Hazard Advisory Committee
Members.
Implementation through Existing Programs
City of Santa Monica addresses statewide planning goals and legislative
requirements through its General Plan, Capital Improvement Plans, and City
Building and Safety Codes. The Natural Hazard Mitigation Plan proVides a
series of recommendations - many of which are closely related to the goals
and objectives of existing planning programs. The City of Santa Monica will
44
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have the opportunity to implement recommended mitigation action items
through existing programs and procedures.
The city of Santa Monica's Building & Safety Department is responsible for
administering the Building & Safety Codes. In addition, the Hazard Advisory
Committee will work with other agencies at the state level to review, develop
and ensure Building & Safety Codes that are adequate to mitigate or present
damage by natural hazards. This is to ensure that life-safety criteria are met
for new construction.
The goals and action items in the mitigation plan may be achieved through
activities recommended in the city's Capital Improvement Plans CCIP).
Various city departments develop CIP plans, and review them on an annual
basis. Upon annual review of the CIPs, the Hazard Mitigation Advisory
Committee will work with the city departments to identify areas that the
hazard mitigation plan action items are consistent with CIP planning goals
and integrate them where appropriate.
Within six months of formal adoption of the mitigation plan, the
recommendations listed above will be incorporated into the process of
existing planning mechanisms at the city level. The meetings of the Hazard
Mitigation Advisory Committee will proVide an opportunity for
committee members to report back on the progress made on the integration
of mitigation planning elements into city planning documents and
procedures.
Economic Analysis of Mitigation Projects
FEMA's approaches to identify the costs and benefits associated with natural
hazard mitigation strategies, measures, or projects fall into two general
categories: benefit/cost analysis and cost-effectiveness analysis.
Conducting benefit/cost analysis for a mitigation activity can assist
communities in determining whether a project is worth undertaking now, in
order to avoid disaster-related damages later.
Cost-effectiveness analysis evaluates how best to spend a given amount of
money to achieve a specific goal. Determining the economic feasibility of
mitigating natural hazards can proVide decision-makers with an
understanding of the potential benefits and costs of an activity, as well as a
basis upon which to compare alternative projects.
Given federal funding, the Hazard Mitigation Advisory Committee will use a
FEMA-approved benefit/cost analysis approach to identify and prioritize
mitigation action items. For other projects and funding sources, the Hazard
Mitigation Advisory Committee will use other approaches to understand the
costs and benefits of each action item and develop a prioritized list. For
45
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more information regarding economic analysis of mitigation action items,
please see Appendix C of the Plan.
EVALUATING AND UPDATING THE PLAN
Formal Review Process
The City of Santa Monica's Natural Hazards Mitigation Plan will be evaluated
on an annual basis to determine the effectiveness of programs, and to reflect
changes in land development or programs that may affect mitigation
priorities. The evaluation process includes a firm schedule and time line, and
identifies the local agencies and organizations participating in plan
evaluation. The convener or designee will be responsible for contacting the
Hazard Mitigation Advisory Committee members and organizing the annual
meeting.
Committee members will be responsible for monitoring and evaluating the
progress of the mitigation strategies in the Plan.
The committee will review the goals and action items to determine their
relevance to changing situations in the city, as well as changes in State or
Federal policy, and to ensure they are addressing current and expected
conditions. The committee will also review the risk assessment portion of the
Plan to determine if this information should be updated or modified, given
any new available data. The coordinating organizations responsible for the
various action items will report on the status of their projects, the success of
various implementation processes, difficulties encountered, success of
coordination efforts, and which strategies should be revised.
The convener will assign the duty of updating the plan to one or more of the
committee members. The designated committee members will have three
months to make appropriate changes to the Plan before submitting it to the
Hazard Committee members, and presenting it to the City Council (or other
authority). The Hazard Mitigation Advisory Committee will also notify all
holders of the city plan when changes have been made. Every five years the
updated plan will be submitted to the State Hazard Mitigation Officer and the
Federal Emergency Management Agency for review.
Continued Public Involvement
City of Santa Monica is dedicated to involving the public directly in review
and updates of the Hazard Mitigation Plan. The Hazard Mitigation Committee
members are responsible for the annual review and update of the plan.
The public will also have the opportunity to proVide feedback about the Plan.
Copies of the Plan will be catalogued and kept at all of the appropriate
agencies in the city. The plan also includes the address and the phone
number of the City's Emergency Services Coordinator, responsible for
46
DRAFT Santa Monica Hazard Mitigation Plan
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keeping track of public comments on the Plan.
A public meeting will also be held after each annual evaluation or when
deemed necessary by the Hazard Mitigation Advisory Committee. The
meetings will provide the public a forum for which they can express its
concerns, opinions, or ideas about the Plan. The City Public Information
Officer will be responsible for using city resources to publicize the annual
public meetings and maintain public involvement through City TV, the City's
web page, and local newspapers.
47
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Section 2 - Specific Natural Hazards
2. 1 E art h qua ke n n n n n n n n n n n n n n n m n n n n n n n n n n n n n n n n n n n n n n n m n n m. 39
2. 2 La n d s lid e . n n n n n n n n n n n n n n n n n m n n n n n n n n n n n n n n n n n n n n n n n m n n m.6 8
2. 3 F I 0 0 d _ n n n n n n n n n n n n n n n n n n n n n n_ n n n n n n n n n n n n n n n n n n n n n n n n_ n n n..8 5
2.4 T sun ami n n n n n n n n n n n n n n n n n n m n n n n n n n n n n n n n n n n n n n n n n n m _m.1 13
2. 5 Wi I d fi res n n n n n n n n n n n n n n n n n n m n n n n n n n n n n n n n n n n n n n n n n n m _m.1 26
2.6 Severe Wi nd sto rm/Th u nd ersto rm mnnnnnnnnnnnnnnnnm_m.1 44
48 DRAFT Santa Monica Hazard Mitigation Plan
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Section 2.1
Earthquake
TABLE OF CONTENTS
Why Are Earthquakes a Threat to the City of Santa Monica......................... 50
History of Earthquake Events in Southern California ...................................52
Causes and Characteristics of Earthquakes in Southern California................ 54
Earthquake Related Hazards................................................................... 56
Hazard Identification............................................................................. 58
Vu I nerabi I ity Assessment........................................................................ 61
Risk Analysis........................................................................................ 62
Community Earthquake Issues................................................................ 63
Existing Mitigation Activities.................................................................... 68
Earthquake Resource Directory............................................................... 73
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Why Are Earthquakes a Threat to the City of Santa Monica
Historical and geological records show that California has a long history of
seismic events. Southern California is probably best known for the San
Andreas Fault, a 400 mile long fault running from the Mexican border to a
point offshore, west of San Francisco. "Geologic studies show that over the
past 1,400 to 1,500 years large earthquakes have occurred at about 130
year intervals on the southern San Andreas fault. As the last large
earthquake on the southern San Andreas occurred in 1857, that section of
the fault is considered a likely location for an earthquake within the next few
decades."i
But San Andreas is only one of dozens of known earthquake faults that criss-
cross Southern California. Some of the better known faults include the
Newport-Inglewood, Whittier, Chatsworth, Elsinore, Hollywood, Los Alamitos,
and Palos Verdes faults. Beyond the known faults, there are a potentially
large number of "blind" faults that underlie the surface of Southern
California. One such blind fault was involved in the Whittier Narrows
earthquake in October 1987.
Although the most famous of the faults, the San Andreas, is capable of
producing an earthquake with a magnitude of 8+ on the Richter scale, some
of the "lesser" faults have the potential to inflict greater damage on the
urban core of the Los Angeles Basin. Seismologists believe that a 6.0
earthquake on the Newport-Inglewood would result in far more death and
destruction than a "great" quake on the San Andreas, because the San
Andreas is relatively remote from the urban centers of Southern California.
For decades, partnerships have flourished between the USGS, Cal Tech, the
California Geological Survey and universities to share research and
educational efforts with Californians. Tremendous earthquake mapping and
mitigation efforts have been made in California in the past two decades, and
public awareness has risen remarkably during this time. Major federal, state,
and local government agencies and private organizations support earthquake
risk reduction, and have made significant contributions in reducing the
adverse impacts of earthquakes. Despite the progress, the majority of
California communities remain unprepared because there is a general lack of
understanding regarding earthquake hazards among Californians.
As experienced in the Northridge earthquake, a major earthquake occurring
in or near the City of Santa Monica may cause many deaths and casualties,
extensive property damage, fires and hazardous material spills and other
ensuing hazards. The effects could be aggravated by aftershocks and by the
secondary affects of fire, hazardous material/chemical accidents and pOSSible
failure of the waterways and dams. The time of day and season of the year
would have a profound effect on the number of dead and injured and the
amount of property damage sustained. Such an earthquake would be
catastrophic in its affect upon the population and could exceed the response
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DRAFT Santa Monica Hazard Mitigation Plan
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capabilities of the individual cities, Los Angeles County Operational Area and
the State of California Emergency Services. Damage control and disaster
relief support would be required from other local governmental and private
organizations, and from the state and federal governments.
Extensive search and rescue operations would be required to assist trapped
or injured persons. Emergency medical care, food and temporary shelter
could be required by injured or displaced persons. Identification and burial of
many dead persons would pose difficult problems; publiC health would be a
major concern. Mass evacuation may be essential to save lives, particularly
in areas downwind from hazardous material releases. Many families would
be separated particularly if the earthquake should occur during working
hours. Emergency operations could be seriously hampered by the loss of
communications and damage to transportation routes within, and to and
from, the disaster area and by the disruption of publiC utilities and services.
The economic impact on the City of Santa Monica from a major earthquake
would be considerable in terms of loss of employment and loss of tax base.
Also, a major earthquake could cause serious damage and/or outage of
computer facilities. The loss of such facilities could curtail or seriously
disrupt the operations of banks, insurance companies and other elements of
the financial community. In turn, this could affect the ability of local
government, business and the population to make payments and purchases.
Table 2.1 Earthquake Events in the Southern California Region
Southern California Region Earthquakes with a Magnitude 5.0 or Greater
1769 Los Angeles Basin 1916 Tejon Pass Region
1800 San Diego Region 1918 San Jacinto
1812 Wrightwood 1923 San Bernardino Region
1812 Santa Barbara Channel 1925 Santa Barbara
1827 Los Angeles Region 1933 Long Beach
1855 Los Angeles Region 1941 Ca rpe nte ri a
1857 Great Fort Tejon Earthquake 1952 Kern County
1858 San Bernardino Region 1954 W. of Wheeler Ridge
1862 San Diego Region 1971 San Fernando
1892 San Jacinto or Elsinore Fault 1973 Point Mugu
1893 Pico Canyon 1986 North Palm Springs
1894 Lytle Creek Region 1987 Whittier Narrows
1894 E. of San Diego 1992 Landers
51 DRAFT Santa Monica Hazard Mitigation Plan
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1899 Lytle Creek Region 1992 Big Bear
1899 San Jacinto and Hemet 1994 Northridge
1907 San Bernardino Region 1999 Hector Mine
1910 Glen Ivy Hot Springs
Source:
http://geology.about.com/gifdynamic/offsite . htm ?site = http%3A%2F%2Fpasadena.wr. usgs. gov% 2Fi nfo% 2Fca h i
st_eqs. html
To better understand the earthquake hazard, the scientific community has
looked at historical records and accelerated research on those faults that are
the sources of the earthquakes occurring in the Southern California region.
Historical earthquake records can generally be divided into records of the
pre-instrumental period and the instrumental period. In the absence of
instrumentation, the detection earthquakes is based on observations and felt
reports, and are dependent upon population density and distribution. Since
California was sparsely populated in the 1800s, the detection of pre-
instrumental earthquakes is relatively difficult. However, two very large
earthquakes, the Fort Tejon in 1857 (7.9) and the Owens Valley in 1872
(7.6) are evidence of the tremendously damaging potential of earthquakes in
Southern California. In more recent times two 7.3 earthquakes struck
Southern California, in Kern County (1952) and Landers (1992). The
damage from these four large earthquakes was limited because the occurred
in areas which were sparsely populated at the time they happened. The
seismic risk is much more severe today than in the past because the
population at risk is in the millions, rather than a few hundred or a few
thousand persons.
The City of Santa Monica is in the vicinity of several known active and
potentially active earthquake faults including the San Andreas which lies
approximately 40 miles east of Santa Monica, the San Jacinto, Santa Monica,
Whittier-Elsinore, and the northeastern end of the Newport-Inglewood Fault
Zone, the source of the 1933 Long Beach earthquake, that is located within
the Los Angeles Metropolitan area. New faults within the region are
continuously being discovered. Scientists have identified almost 100 faults in
the Los Angeles area known to be capable of a magnitude 6.0 or greater
earthquake.
History of Earthquake Events in Southern California
Since seismologists started recording and measuring earthquakes, there
have been tens of thousands of recorded earthquakes in Southern California,
most with a magnitude below three. No community in Southern California is
beyond the reach of a damaging earthquake. Table 2.1 describes the
historical earthquake events that have affected Southern California.
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DRAFT Santa Monica Hazard Mitigation Plan
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The 1994 Northridge Earthquake
The January 17, 1994 magnitude 6.7 Northridge Earthquake (thrust fault),
with its epicenter beneath Reseda, produced severe ground motions, caused
57 deaths, 9,253 injuries and left over 20,000 people displaced within the
Los Angeles area. It was the most expensive disaster in the history of Santa
Monica, which sustained more than $250 million in damage. More than 530
buildings, including 2,300 housing units, were red- or yellow-tagged,
rendering them uninhabitable or with limited accessibility. An estimated
16,000 apartments, condominiums or houses sustained some damage and
were green-tagged, or still inhabitable.
Because of the severe damage in Santa Monica, city officials implemented a
number of measures to expedite recovery efforts, including a streamlined
permit process and fee waivers, as well as rent increases to cover
earthquake repairs in rent-controlled buildings. Funds received from the
Federal Emergency Management Agency included $93.4 million for home
repairs, temporary housing, infrastructure repairs and retrofitting to help
lessen the effects of future disasters.
The earthquake affected almost every building on the Santa Monica College
with an estimated $80 million spent on the recovery effort. Santa Monica
Hospital Medical Center suffered significant damage leading to the hospital's
partnership with UCLA. The hospital's pavilion and tower sustained about $15
million in immediate damage, forcing the tower's closure for nine months. All
of the hospital's operations were consolidated into the pavilion.
Saint John's Hospital's north wing, with its 185 beds, the hospital nursery
and the neo-natal intensive care unit, sustained the most damage. Those
beds and services were immediately evacuated and moved to other parts of
the facility. The hospital stayed open for three days before it was forced to
shut down completely because of the extensive damage. On October 3,
1994, Saint John's was fully operational minus its north wing, which was
demolished. The cost of repairs totaled $32 million. In July 1998, Saint
John's broke ground on a $271 million replacement project, scheduled to be
finished by the year 2005. To help survive any future disasters, the new
faCility will have its own water supply, sewage system and communications
backup system.
By February 1999, 517 of the 530 buildings that were red- or yellow-tagged
had been repaired or have repair permits. The city issued more than 3,400
repair permits for earthquake damaged properties. Fifty-three buildings were
demolished because of catastrophic earthquake damage.
Scientists have stated that such devastating shaking should be considered
the norm near any large thrust earthquake. Recent reports from scientists of
the U.S. Geological Survey and the Southern California Earthquake Center
53
DRAFT Santa Monica Hazard Mitigation Plan
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say that the Los Angeles Area could expect one earthquake every year of
magnitude 5.0 or more for the foreseeable future.
Causes and Characteristics of Earthquakes in Southern California
EARTHQUAKE FAULTS
A fault is a fracture along between blocks of the
earth's crust where either side moves relative to
the other along a parallel plane to the fracture.
Strike-slip
Strike-slip faults are vertical or almost vertical rifts
where the earth's plates move mostly horizontally.
From the observers perspective, if the opposite
block looking across the fault moves to the right,
the slip style is called a right lateral fault; if the
block moves left, the shift is called a left lateral
fault.
Dip-slip
Dip-slip faults are slanted fractures where the
blocks mostly shift vertically. If the earth above an
inclined fault moves down, the fault is called a
normal fault, but when the rock above the fault
moves up, the fault is called a reverse fault. Thrust
faults have a reverse fault with a dip of 45 0 or less.
54
DRAFT Santa Monica Hazard Mitigation Plan
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Map 2.1
Southern California
Earthquake Fault Map
o 25 Miles
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esca rpements
55
DRAFT Santa Monica Hazard Mitigation Plan
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Dr. Kerry Sieh of Cal Tech has investigated the San Andreas fault at Pallett
Creek. "The record at Pallett Creek shows that rupture has recurred about
every 130 years, on average, over the past 1500 years. But actual intervals
have varied greatly, from less than 50 years to more than 300. The physical
cause of such irregular recurrence remains unknown." ii Damage from a
great quake on the San Andreas would be widespread throughout Southern
California.
Earthquake Related Hazards
Ground shaking, landslides, liquefaction, and amplification are the specific
hazards associated with earthquakes. The severity of these hazards depends
on several factors, including soil and slope conditions, proximity to the fault,
earthquake magnitude, and the type of earthquake.
Ground Shaking
Ground shaking is the motion felt on the earth's surface caused by
seismic waves generated by the earthquake. It is the primary cause of
earthquake damage. The strength of ground shaking depends on the
magnitude of the earthquake, the type of fault, and distance from the
epicenter (where the earthquake originates). Buildings on poorly
consolidated and thick soils will typically see more damage than
buildings on consolidated soils and bedrock.
Earthquake Induced landslides
Earthquake induced landslides are secondary earthquake hazards that
occur from ground shaking. They can destroy the roads, buildings,
utilities, and other critical facilities necessary to respond and recover
from an earthquake. Many communities in Southern California have a
high likelihood of encountering such risks, especially in areas with
steep slopes.
Liquefaction
Liquefaction occurs when ground shaking causes wet granular soils to
change from a solid state to a liquid state. This results in the loss of
soil strength and the soil's ability to support weight. Buildings and their
occupants are at risk when the ground can no longer support these
buildings and structures. Many communities in Southern California are
built on ancient river bottoms and have sandy soil. In some cases this
ground may be subject to liquefaction, depending on the depth of the
water table.
Am pi ification
Soils and soft sedimentary rocks near the earth's surface can modify
ground shaking caused by earthquakes. One of these modifications is
amplification. Amplification increases the magnitude of the seismic
waves generated by the earthquake. The amount of amplification is
influenced by the thickness of geologic materials and their physical
56
DRAFT Santa Monica Hazard Mitigation Plan
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properties. Buildings and structures built on soft and unconsolidated
soils can face greater risk.iii Amplification can also occur in areas with
deep sediment filled basins and on ridge tops.
Map 2.2
Seismic Zones in California
Seismic Zones In California
~
Darker Shaded Areas indicate Greater Potential Shaking
Source: USGS Website
57
DRAFT Santa Monica Hazard Mitigation Plan
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Earthquake Hazard Assessment
Hazard Identification
In California, many agencies are focused on seismic safety issues: the State's
Seismic Safety Commission, the Applied Technology Council, Governor's
Office of Emergency Services, United States Geological Survey, Cal Tech, the
California Geological Survey as well as a number of universities and private
foundations.
These organizations, in partnership with other state and federal agencies,
have undertaken a rigorous program in California to identify seismic hazards
and risks including active fault identification, bedrock shaking, tsunami
inundation zones, ground motion amplification, liquefaction, and earthquake
induced landslides. Seismic hazard maps have been published and are
available for many communities in California through the State Division of
Mines and Geology. Map 2.1 illustrates the known earthquake faults in
Southern California.
58
DRAFT Santa Monica Hazard Mitigation Plan
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Santa Monica Fault
The Santa Monica fault is part of the Transverse Ranges Southern Boundary
fault system, a west-trending system of reverse, oblique-slip, and strike-slip
faults that extends for more than 200 km along the southern edge of the
Transverse Ranges (Dolan et aI., 1997, 2000a). Other faults in this system
are the Hollywood and Raymond faults. The Anacapa-Dume, Malibu Coast,
Santa Cruz Island, and Santa Rosa Island faults to the west are also part of
this system.
The Santa Monica fault extends east from the coastline in Pacific Palisades
through Santa Monica and West Los Angeles and merges with the Hollywood
fault at the West Beverly Hills Lineament in Beverly Hills, west of the crossing
of Santa Monica Boulevard and Wilshire Boulevard, where its strike is
northeast. Onshore, the fault offsets the surface 2-3.5 km south of the Santa
Monica Mountains range front.iv
Map 2.4
Santa Monica Fault
-- Earthqu ake Plan ning Seen ariD --
Peak Acee!. Map (in %g) for Santa Monica M6.6 Scenario
Scenario Date: Mon Ju110. 2001 050000 AM PDT M 0.0 N34.03 W118.5.2 Depth 13.0km
34"
PUHJ~JNG SCEI\IAHIO ONLY n P,ccesssd: 1,lon Jan 12. 2004 12:10:17 PM PST
60
DRAFT Santa Monica Hazard Mitigation Plan
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Santa Monica Fault
TYPE OF FAULTING: left-reverse
LENGTH: 24 km
NEARBY COMMUNITIES: Pacific Palisades, Westwood, Beverly Hills,
Santa Monica
MOST RECENT SURFACE RUPTURE: Late Quaternary
SLIP RATE: between 0.27 and 0.39 mmjyr
INTERVAL BETWEEN MAJOR RUPTURES: unknown
PROBABLE MAGNITUDES: Mw6.0 - 7.0 (?)
OTHER NOTES: This is a north-dipping fault. Its slip rate may be
greatest at its western end.v
In California, each earthquake is followed by revisions and improvements in
the Building Codes. The 1933 Long Beach resulted in the Field Act, affecting
school construction. The 1971 Sylmar earthquake brought another set of
increased structural standards. Similar re-evaluations occurred after the
1989 Loma Prieta and 1994 Northridge earthquakes. These code changes
have resulted in stronger and more earthquake resistant structures.
The Alquist-Priolo Earthquake Fault Zoning Act was passed in 1972 to
mitigate the hazard of surface faulting to structures for human occupancy.
This state law was a direct result of the 1971 San Fernando Earthquake,
which was associated with extensive surface fault ruptures that damaged
numerous homes, commercial buildings, and other structures. Surface
rupture is the most easily avoided seismic hazard.vi
The Seismic Hazards Mapping Act, passed in 1990, addresses non-surface
fault rupture earthquake hazards, including liquefaction and seismically
induced landslides.vii The State Department of Conservation operates the
Seismic Mapping Program for California. Extensive information is available at
their website: http://qmw.consrv.ca.qov/shmp/index.htm
Vulnerability Assessment
The effects of earthquakes span a large area, and large earthquakes
occurring in many parts of the Southern California region would probably be
felt throughout the region. However, the degree to which the earthquakes
are felt, and the damages associated with them may vary. At risk from
earthquake damage are large stocks of old buildings and bridges: many high
tech and hazardous materials facilities: extensive sewer, water, and natural
gas pipelines; earth dams; petroleum pipelines; and other critical facilities
and private property located in the county. The relative or secondary
earthquake hazards, which are liquefaction, ground shaking, amplification,
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and earthquake-induced landslides, can be just as devastating as the
earthquake.
The California Geological Survey has identified areas most vulnerable to
liquefaction. Liquefaction occurs when ground shaking causes wet granular
soils to change from a solid state to a liquid state. This results in the loss of
soil strength and the soil's ability to support weight. Buildings and their
occupants are at risk when the ground can no longer support these buildings
and structures. Map 2.3 identifies the local population centers in City of
Santa Monica that have soils vulnerable to liquefaction.
Southern California has many active landslide areas, and a large earthquake
could trigger accelerated movement in these slide areas, in addition to
jarring loose other unknown areas of landslide risk.
Risk Analysis
Risk analysis is the third phase of a hazard assessment. Risk analysis
involves estimating the damage and costs likely to be experienced in a
geographic area over a period of timeviii. Factors included in assessing
earthquake risk include population and property distribution in the hazard
area, the frequency of earthquake events, landslide susceptibility, buildings,
infrastructure, and disaster preparedness of the region. This type of analysis
can generate estimates of the damages to the region due to an earthquake
event in a specific location. FEMA's software program, HAZUS, uses
mathematical formulas and information about building stock, local geology
and the location and size of potential earthquakes, economic data, and other
information to estimate losses from a potential earthquake.ix The HAZUS
software is available from FEMA at no cost.
For greater Southern California there are multiple worst case scenarios,
depending on which fault might rupture, and which communities are in
proximity to the fault. But damage will not necessarily be limited to
immediately adjoining communities. Depending on the hypocenter of the
earthquake, seismic waves may be transmitted through the ground to
unsuspecting communities. In the Northridge 1994 earthquake, Santa
Monica suffered extensive damage, even though there was a range of
mountains between it and the origin of the earthquake.
Damages for a large earthquake almost anywhere in Southern California are
likely to run into the billions of dollars. Although building codes are some of
the most stringent in the world, ten's of thousands of older existing buildings
were built under much less rigid codes. California has laws affecting
unreinforced masonry buildings (URM's) and although many building owners
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have retrofitted their buildings, hundreds of pre-1933 buildings still have not
been brought up to current standards.
Non-structural bracing of equipment and contents is often the most cost-
effective type of seismic mitigation. Inexpensive bracing and anchoring may
be the most cost effective way to protect expensive equipment. Non-
structural bracing of equipment and furnishings will also reduce the chance of
injury for the occupants of a building.
Community Earthquake Issues
What is Susceptible to Earthquakes?
Earthquake damage occurs because humans have built structures that
cannot withstand severe shaking. Buildings, airports, schools, and lifelines
(highways and utility lines) suffer damage in earthquakes and can cause
death or injury to humans. The welfare of homes, major businesses, and
public infrastructure is very important. Addressing the reliability of buildings,
critical facilities, and infrastructure, and understanding the potential costs to
government, businesses, and individuals as a result of an earthquake, are
challenges faced by the city.
Damage to Vital Public Services, Systems and Facilities
Communications
Telephone systems will be affected by system failure, overloads, loss of
electrical power and pOSSible failure of some alternate power systems.
Immediately after the event, numerous failures will occur coupled with
saturation overloads. This will disable up to 80% of the telephone system for
approximately one day. In light of the expected situation, emergency
planners should not plan on the use of telephone systems for the first few
days after the event.
During a major emergency, communication from the City's Emergency
Operations Center (EOC) to the outside world is a primary necessity. Twenty
individual private lines are currently connected directly to the EOC from
General Telephone. One line is connected through the City's telephone switch
through one Police Department extension. This allows the EOC to operate
independently of the City Hall network should the system be damaged or fail
to operate. The obvious disadvantage of this system is the potential for
damage to occur to the hard wire connections between the EOC and General
Telephone.
Four separate and independent radio systems are available for emergency
use by EOC personnel. They are already in place and are operated by the
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Environmental Public Works Management (EPWM), Fire Department, the
Police Department and Transportation Department. Each system has its own
unique characteristics. In a disaster, it is pOSSible that all systems could be
rendered partially or completely inoperative.
Additionally, the Disaster Communication Services (DCS) provides amateur
radio communication. DCS Communication equipment is located at the EOC,
Fire Station One, Fire Station Five, and the Alternate EOC at the Ken Edwards
Center.
Environmental and Public Works Management (EPWM)
Communications
The backbone of the EPWM radio system is a fully repeated
receiver/transmitter located on the reservoir property in the 800-900 block of
Franklin Street. There are five locations within the city that have remote
control links connected to the system; City Hall; Police Headquarters; City
Yards; Clover Park; and the Fire Department. The primary area of concern
during a disaster would be whether or not the telephone lines would continue
to function from the control points and receiver locations. If telephone lines
were to fail and if the Franklin equipment were not damaged, the system
would continue to operate by itself, for car to car operation, but with some
range limitation. There is good pOSSibility that the back-up system located at
2500 Michigan would enable one of these systems to work during and after a
disaster.
Fire Department Communications
The Fire Department's radio system functions through three remote receivers
which are connected via telephone lines to the main receiver site located at
2500 Michigan Avenue. The major disadvantage with this type of system lies
with the telephone connections. If the main lines between the dispatcher and
transmitter should fail, the dispatcher would lose the ability to hear or
transmit to field units. To mitigate this problem, the fire department has
installed a back-up transmitter at their dispatch center. Although providing
only reduced coverage, this back-up will provide emergency communication
should the main transmitter site fail.
Police Department Communications
The Police Department's radio system operates from their main transmitter
site located on the roof of 100 Wilshire Boulevard, formally known as the GTE
building. Receivers are placed in four strategic locations around the city and
received signals are routed via telephone lines to Police Headquarters where
the best signal is selected and routed back up to the 100 Wilshire site for
transmission. As in other systems the telephone lines have been determined
to be the weak link. Once this system is replaced by microwave, Police
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communication will be fault free as long as electrical power is not interrupted
and the building structures are in place. Generator power is available at the
Police Facility, 100 Wilshire and the City Yards. Some of these locations also
have battery back-up as do all the sites without generator power. The City
Hall telephone network, the 911 telephone network, and the Police dispatch
equipment are all supported by back-up battery power which is in turn
charged by the generator. Radio systems are expected to be 40 to 75%
effective; microwave systems, 30% effective or less.
Dam/Flood Control Channels
No dam/flood control channels exist in Santa Monica. Portions of the City
may be subject to flooding, due to flash flooding, urban flooding (storm drain
failure/infrastructure breakdown), river channel overflow, downstream
flooding, etc.) The City has not historically been vulnerable to storm surge
inundation associated with hurricanes and tropical storms.
Stone Canyon Reservoir
The Stone Canyon Reservoir is located in the City of Los Angeles. There is a
likelihood that the 10,370 acre feet capacity Stone Canyon Reservoir above
the City of Brentwood would rupture in a major earthquake, inundating
Brentwood and portions of West Los Angeles, and depositing no less than
several inches of water on the northeast portion of Santa Monica.
Riviera Reservoir
The Riviera Reservoir, 1252 Capri, Los Angeles, is owned by the City of Santa
Monica and located about two miles north of the City in Santa Monica
Canyon. The California Department of Water Resources Bulletin NO.17 lists
the reservoir as having a height of 40 feet and a storage capacity of 76 acre-
feet, which translates to approximately 25 million gallons.
The Riviera Reservoir is an off-stream, covered storage reservoir built with
vertical concrete walls. These walls are keyed top and bottom to the roof and
foundations. The north and west sidewalls on the south and east have
compacted backfill in front of them. These are the sides through which water
will pass should a failure occur.
If the failure were to occur on the east side, the structures, located at the
Riviera Golf Course, immediately below the dam will definitely be in jeopardy.
If the south side of the dam were to fail, no structures would be harmed.
However, the golf course would be flooded.
Flood waters released during the reservoir failure would empty onto the
Riviera Country Golf Course, eventually flowing into the Santa Monica Creek.
The flood control channels will contain the flood waters directing them to the
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Pacific Ocean. Santa Monica Creek located in the City of Los Angeles, is dry
the majority of the time and is not likely to be carrying flow at a time when
the reservoir might fail. Damage to any homes adjacent to the golf course is
considered unlikely. The travel time of the flood flows to the flood control
channel would be within 15 minutes.
Electrical Power
Major power plants are expected to sustain some damage due to liquefaction
and the intensity of the earthquake. During the Northridge earthquake power
was restored within 24 hours in most areas of Santa Monica. Up to 60% of
the system load may be interrupted immediately following the initial shock.
According to representatives of Southern California Edison Company, the
electrical power will not be rerouted and will be lost for an undefined period
of time. Much of the imported power is expected to be lost. In some areas of
greatest shaking it should be anticipated that some of the distribution lines,
both underground and surface, will be damaged. Much of the affected area
may have service restored in days; damaged areas with underground
distribution may require a longer time. Loss of Southern California Edison
transmission lines is possible.
Fire Operations
Although total collapse of fire stations is not expected, pOSSible disruption of
utilities, inoperable apparatus doors and loss of power can create major
problems. Numerous fires due to disruption of power and natural gas
networks can be expected. Many connections to major water sources may be
out and storage facilities would have to be relied on; water supply could vary
from little or none to inadequate. First response from fire personnel is
expected to be assessment of the area to establish what is needed to
determine response and recovery needs. Operations may take days because
of the disruption of transportation routes for fire department personnel and
equipment.
Secondary responses by the Fire Service after assessment will be placed
upon diversion of resources to accomplish search and rescue of trapped
persons and extinguishment of fires with conflagration potential. Major
problems the Fire Service should expect are loss of power and water,
restricted mobility due to debris, and pOSSible loss of primary dispatch
capability.
Highways and Bridges
Damage to freeway systems is expected to be major as experienced in the
partial collapse of the Santa Monica Freeway (U.S. Highway 10) during the
Northridge earthquake. Any inner surface transportation routes could be
subject to delays and detours. A major portion of surface streets in the
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vicinity of freeways could be blocked due to collapsed overpasses. Many
surface streets in the older central business districts will be blocked by debris
from buildings, falling electrical wires and pavement damage.
Natural Gas
Damage to natural gas facilities will consist primarily of (a) some isolated
breaks in major transmission lines, and (b) innumerable breaks in mains and
individual service connections within the distribution systems, particularly in
the areas of intense ground shaking. These many leaks in the distribution
system will affect a major portion of the urban areas, resulting in a loss of
service for extended periods. Fires should be expected at the sites of a small
percentage of ruptures both in the transmission lines and the distribution
system. Transmission pipelines serving the general basin area are most
vulnerable to damage.
Railroads
No operational railroads exist in the City of Santa Monica. However, it is
expected that 21 of the 59 route segments serving the Southern California
region could be unavailable for post-earthquake service; the 21 segments
include all major connections with the north. The post earthquake capacity to
serve both the Los Angeles and Orange County areas would be very small-
probably no more than 5 trains a day. This is a dramatic loss from the 120 to
140 trains per day that can currently enter the area. Many railroad bridges
are susceptible to damage because of age, design and construction. Some
lines could be blocked because of damage to freeway overpass structures.
Sanitation Systems
The Sewer System is operated and maintained by the City of Santa Monica.
Santa Monica sewage is treated by the City of Los Angeles at the Hyperion
Treatment Plant in Playa Del Rey.
Many waste water treatment facilities could be out of service from 4 to 6
months depending on the damage caused by the severity of intensity and
liquefaction. There is a limited volume of storage available in the waste water
treatment plants; if the treatment infrastructure cannot be restored before
storage is exceeded, the waste water will require discharge with emergency
chlorination to reduce health hazards. Overflow of sewage through manholes
and from ponds can be expected due to breakage in mains and loss of power.
As a result, there will be a danger of excessive collection of explosive gas in
sewer mains, and flow of untreated sewage in some street gutters. Many
residential sewer connections will break and plug.
Water Supply
Most of the City's water is provided by the Metropolitan Water District. In a
major earthquake, two of the three major aqueducts serving Southern
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California are expected to be out of service from 3 to 6 months following the
event; only the Colorado River Aqueduct is expected to remain in service.
This indicates the imported water supply to Los Angeles County may be only
partial for a 3 to 6 months period. Several ruptures are anticipated along the
water pipelines in the County. Anticipated damage to reservoir outlet works
could take weeks to repair. The majority of water wells are expected to be
disabled by loss of electricity and the lack of backup power sources. In
addition, shear forces could render about a third of the wells inoperative for
an indefinite period. Water availability and distribution for needed life
support, to treat the sick and injured and for fire suppression activities is of
MAJOR concern to each community.
Existing Mitigation Activities
Existing mitigation activities include current mitigation programs and
activities that are being implemented by county, regional, state, or federal
agencies or organizations.
City of Santa Monica Codes
Implementation of earthquake mitigation policy most often takes place at the
local government level. The City of Santa Monica Department of Building and
Safety enforces building codes pertaining to earthquake hazards.
The following sections of the City's Building Code address the earthquake
hazard:
8.16
8.56
Supplemental Earthquake Provisions
8.16.020 Earthquake Design Provisions
8.16.040 Concrete and Masonry Chimneys/Veneer
8.16.050 Steel Construction
8.16.060 Wood Construction
Northridge Earthquake Provisions
8.56.010 Repair, Reconstruction and Reinforcement of
Unreinforced Masonry Buildings Requirements
Standards for Repair, Reconstruction and
Reinforcement of Unreinforced Masonry Buildings
Requirements
Repair, Reconstruction and Reinforcement of
Soft Story Buildings
Seismic Strengthening Provisions for Unreinforced Masonry
Bearing Wall Buildings
Seismic Strengthening Provisions for Existing Concrete and
Reinforced Masonry Wall Buildings with Flexible Diaphrams
Voluntary Seismic Strengthening Provisions for Cripple Walls
and Sill Plate Anchorage in Single-Family Dwellings
Seismic Strengthening Provisions for Soft, Weak or Open Front
8.56.020
8.56.030
8.60
8.64
8.68
8.72
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Walls in Light, Wood-Framed Buildings
8.76 Seismic Strengthening Provisions for Existing Welded Steel
Moment Frame Structures
8.80 Seismic Strengthening Provisions for Existing Non-Ductile
Concrete Buildings
The City of Santa Monica Planning Department enforces the zoning and land
use regulations relating to earthquake hazards.
Generally, these codes seek to discourage development in areas that could
be prone to flooding, landslide, wildfire and / or seismic hazards; and where
development is permitted, that the applicable construction standards are
met. Developers in hazard-prone areas may be required to retain a qualified
professional engineer to evaluate level of risk on the site and recommend
appropriate mitigation measures.
Coordination Among Building Officials
The City of Santa Monica Building Code sets the minimum design and
construction standards for new buildings. In 2002 the City of Santa Monica
adopted the most recent seismic standards in its building code, which
requires that new buildings be built at a higher seismic standard.
Businesses/Private Sector
Natural hazards have a devastating impact on businesses. In fact, of all
businesses which close following a disaster, more than forty-three percent
never reopen, and an additional twenty-nine percent close for good within
the next two years.x The Institute of Business and Home Safety has
developed "Open for Business", which is a disaster planning toolkit to help
gUide businesses in preparing for and dealing with the adverse affects natural
hazards. The kit integrates protection from natural disasters into the
company's risk reduction measures to safeguard employees, customers, and
the investment itself. The gUide helps businesses secure human and physical
resources during disasters, and helps to develop strategies to maintain
business continuity before, during, and after a disaster occurs.
Hospitals
"The Alfred E. Alquist Hospital Seismic Safety Act ("Hospital Act") was
enacted in 1973 in response to the moderate Magnitude 6.6 Sylmar
Earthquake in 1971 when four major hospital campuses were severely
damaged and evacuated. Two hospital buildings collapsed killing forty seven
people. Three others were killed in another hospital that nearly collapsed.
In approving the Act, the Legislature noted that:
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Hospitals, that house patients who have less than the capacity of normally
healthy persons to protect themselves, and that must be reasonably capable
of providing services to the public after a disaster, shall be designed and
constructed to resist, insofar as practical, the forces generated by
earthquakes, gravity and winds. (Health and Safety Code Section 129680)
When the Hospital Act was passed in 1973, the State anticipated that, based
on the regular and timely replacement of aging hospital facilities, the
majority of hospital buildings would be in compliance with the Act's standards
within 25 years. However, hospital buildings were not, and are not, being
replaced at that anticipated rate. In fact, the great majority of the State's
urgent care facilities are now more than 40 years old.
The moderate Magnitude 6.7 Northridge Earthquake in 1994 caused $3
billion in hospital-related damage and evacuations. Twelve hospital buildings
constructed before the Act were cited (red tagged) as unsafe for occupancy
after the earthquake. Those hospitals that had been built in accordance with
the 1973 Hospital Act were very successful in resisting structural damage.
However, nonstructural damage (for example, plumbing and ceiling systems)
was still extensive in those post-1973 buildings
Senate Bill 1953 ("SB 1953"), enacted in 1994 after the Northridge
Earthquake, expanded the scope of the 1973 Hospital Act. Under SB 1953, all
hospitals are required, as of January 1, 2008, to survive earthquakes without
collapsing or posing the threat of significant loss of life. The 1994 Act further
mandates that all existing hospitals be seismically evaluated, and retrofitted,
if needed, by 2030, so that they are in substantial compliance with the Act
(which requires that the hospital buildings be reasonably capable of providing
services to the publiC after disasters). SB 1953 applies to all urgent care
facilities (including those built prior to the 1973 Hospital Act) and affects
approximately 2,500 buildings on 475 campuses.
SB 1953 directed the Office of Statewide Health Planning and Development
("OSHPD"), in consultation with the Hospital Building Safety Board, to
develop emergency regulations including "...earthquake performance
categories with subgradations for risk to life, structural soundness, building
contents, and nonstructural systems that are critical to providing basic
services to hospital inpatients and the publiC after a disaster." (Health and
Safety Code Section 130005)
The Seismic Safety Commission Evaluation of the State's Hospital Seismic
Safety Pol icies
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In 2001, recognizing the continuing need to assess the adequacy of policies,
and the application of advances in technical knowledge and understanding,
the California Seismic Safety Commission created an Ad Hoc Committee to
re-examine the compliance with the Alquist Hospital Seismic Safety Act. The
formation of the Committee was also prompted by the recent evaluations of
hospital buildings reported to OSHPD that revealed that a large percentage
(40%) of California's operating hospitals are in the highest category of
collapse risk.".xi
California Earthquake Mitigation Legislation
California is painfully aware of the threats it faces from earthquakes. Dating
back to the 19th century, Californians have been killed, injured, and lost
property as a result of earthquakes. As the State's population continues to
grow, and urban areas become even more densely built up, the risk will
continue to increase. For decades the Legislature has passed laws to
strengthen the built environment and protect the citizens. Table xx-xx
provides a sampling of some of the 200 plus laws in the State's codes.
Table xx-xx: Partial List of the Over 200 California Laws on Earthquake Safety
Government Code Creates Seismic Safety Commission.
Section 8870-8870.95
Government Code Established the California Center for Earthquake
Section 8876.1-8876.10 Engineering Research.
Public Resources Code Authorized a prototype earthquake prediction system
Section 2800-2804.6 along the cental San Andreas fault near the City of
Parkfield.
Public Resources Code Continued the Southern California Earthquake
Section 2810-2815 Preparedness Project and the Bay Area Regional
Earthquake Preparedness Project.
Health and Safety Code The Seismic Safety Commission and State Architect,
Section 16100-16110 will develop a state policy on acceptable levels of
earthquake risk for new and existing state-owned
buildings.
Government Code Established the California Earthquake Hazards
Section 8871-8871.5 Reduction Act of 1986.
Health and Safety Code Defined earthquake performance standards for
Section 130000-130025 hospitals.
Public Resources Code Established the California Earthquake Education
Section 2805-2808 Project.
Government Code Established the Earthquake Research Evaluation
Section 8899.10-8899.16 Conference.
Public Resources Code Established the Alquist-Priolo Earthquake Fault Zoning
Section 2621-2630 2621. Act.
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Government Code Created the Earthquake Safety and Public Buildings
Section 8878.50-8878.52 Rehabilitation Bond Act of 1990.
8878.50.
Education Code Section Established emergency procedure systems in
35295-35297 35295. kindergarten through grade 12 in all the public or
private schools.
Health and Safety Code Established standards for seismic retrofitting of
Section 19160-19169 unreinforced masonry buildings.
Health and Safety Code Required all child day care facilities to include an
Section 1596.80- Earthquake Preparedness Checklist as an attachment
1596.879 to their disaster plan.
Source: http://www.leginfo.ca.gov/calaw.html
Earthquake Education
Earthquake research and education activities are conducted at several major
universities in the Southern California region, including Cal Tech, USC, UCLA,
UCSB, UCI, and UCSB. The local clearinghouse for earthquake information is
the Southern California Earthquake Center located at the University of
Southern California, Los Angeles, CA 90089, Telephone: (213) 740-5843,
Fax: (213) 740-0011, Email: SCEinfo@usc.edu, Website:
http://www.scec.org. The Southern California Earthquake Center (SCEC) is a
community of scientists and specialists who actively coordinate research on
earthquake hazards at nine core institutions, and communicate earthquake
information to the public. SCEC is a National Science Foundation (NSF)
Science and Technology Center and is co-funded by the United States
Geological Survey (USGS).
In addition, Los Angeles County along with other Southern California
counties, sponsors the Emergency Survival Program (ESP), an educational
program for learning how to prepare for earthquakes and other disasters.
Many school districts have very active emergency preparedness programs
that include earthquake drills and periodic disaster response team exercises.
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Earthquake Resource Directory
Local and Regional Resources
Los Anaeles Countv Public Works Deoartment
Level: County Hazard: Multi
900 S. Fremont Ave.
Alhambra, CA 91803
http://ladpw .org
Ph: 626-458-5100 Fx:
Notes: The Los Angeles County Department of Public Works protects property and
promotes public safety through Flood Control, Water Conservation, Road
Maintenance, Bridges, Buses and Bicycle Trails, Building and Safety, Land
Development, Waterworks, Sewers, Engineering, Capital Projects and Airports
Southern California Earthquake Center (SCEC)
Level: Regional Hazard: www.scec.org
Earthquake
3651 Trousdale Parkway Suite 169
Los Angeles, CA 90089-0742 Ph: 213-740-5843 Fx: 213/740-0011
Notes: The Southern California Earthquake Center (SCEC) gathers new
information about earthquakes in Southern California, integrates this information
into a comprehensive and predictive understanding of earthquake phenomena,
and communicates this understanding to end-users and the general public in
order to increase earthquake awareness, reduce economic losses, and save lives.
State Resources
California Department of Transportation (CaITrans)
Level: State Hazard: Multi http://www.dot.ca.gov/
120 S. Spring Street
Los Angeles, CA 90012
Ph: 213-897-3656 Fx:
Notes: CalTrans is responsible for the design, construction, maintenance, and
operation of the California State Highway System, as well as that portion of the
Interstate Highway System within the state's boundaries. Alone and in
partnership with Amtrak, CalTrans is also involved in the support of intercity
passenger rail service in California.
California Resources Agency
Level: State Hazard: Multi
http://resources.ca.gov/
Suite 1311
1416 Ninth Street
Sacramento, CA 95814
Ph: 916-653-5656 Fx:
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Notes: The California Resources Agency restores, protects and manages the
state's natural, historical and cultural resources for current and future generations
using solutions based on science, collaboration and respect for all the
communities and interests involved.
California Division of Mines and Geology (DMG)
Level: State Hazard: Multi www.consrv.ca.gov/cgs/index.htm
801 K Street MS 12-30
Sacramento, CA 95814 Ph: 916-445-1825 Fx: 916-445-5718
Notes: The California Geological Survey develops and disseminates technical
information and advice on California's geology, geologic hazards, and mineral
resou rces.
California Department of Conservation: Southern California Regional
Office
Level: State Hazard: Multi www.consrv.ca.gov
655 S. Hope Street
Los Angeles, CA 90017-2321
#700
Ph: 213-239-0878 Fx: 213-239-0984
Notes: The Department of Conservation provides services and information that
promote environmental health, economic vitality, informed land-use decisions and
sound management of our state's natural resources.
California Planning Information Network
Level: State Hazard: Multi www.calpin.ca.gov
Ph:
Fx:
Notes: The Governor's Office of Planning and Research (OPR) publishes basic
information on local planning agencies, known as the California Planners' Book of
Lists. This local planning information is available on-line with new search
capabilities and up-to-the- minute updates.
Governor's Office of Emergency Services (OES)
Level: State Hazard: Multi www.oes.ca.gov
P.O. Box 419047
Rancho Cordova, CA 95741-9047
Ph: 916 845- 8911 Fx: 916 845- 8910
Notes: The Governor's Office of Emergency Services coordinates overall state
agency response to major disasters in support of local government. The office is
responsible for assuring the state's readiness to respond to and recover from
natural, manmade, and war-caused emergencies, and for assisting local
governments in their emergency preparedness, response and recovery efforts.
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Federal and National Resources
Building Seismic Safety Council (BSSC) I
Level: National Hazard: www.bssconline.org
Earthquake
1090 Vermont Ave., NW Suite 700
Washington, DC 20005 Ph: 202-289-7800 Fx: 202-289-109
Notes: The Building Seismic Safety Council (BSSC) develops and promotes
building earthquake risk mitigation regulatory provisions for the nation.
Federal Emergency Management Agency, Region IX
Level: Federal Hazard: Multi www.fema.gov
1111 Broadway
Oakland, CA 94607
Suite 1200
Ph: 510-627-7100 Fx: 510-627-7112
Notes: The Federal Emergency Management Agency is tasked with responding to,
planning for, recovering from and mitigating against disasters.
Federal Emergency Management Agency, Mitigation Division
Level: Federal Hazard: Multi www.fema.gov/fima/planhowto.shtm
500 C Street, S. W.
Washington, D.C. 20472
I
Notes: The Mitigation Division manages the National Flood Insurance Program and
oversees FEMA's mitigation programs. It has a number of programs and activities
which provide citizens Protection, with flood insurance; Prevention, with
mitigation measures and Partnerships, with communities throughout the country.
United States Geological Survey
Level: Federal Hazard: Multi
Ph: 202-566-1600
Fx:
http://www.usgs.gov/
345 Middlefield Road
Menlo Park, CA 94025 Ph: 650-853-8300 Fx:
Notes: The USGS provides reliable scientific information to describe and
understand the Earth; minimize loss of life and property from natural disasters;
manage water, biological, energy, and mineral resources; and enhance and
protect our quality of life.
Western States Seismic Policy Council (WSSPC)
Level: Regional Hazard: www.wsspc.org/home.html
Earthquake
125 California Avenue Suite D201, #1
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Palo Alto, CA 94306
Ph: 650-330-1101 Fx: 650-326-1769
Notes: WSSPC is a regional earthquake consortium funded mainly by FEMA. Its
website is a great resource, with information clearly categorized - from policy to
engineering to education.
Institute for Business & Home Safety
Level: National Hazard: Multi http://www.ibhs.org/
4775 E. Fowler Avenue
Tampa, FL 33617
Ph: 813-286-3400 Fx: 813-286-9960
The Institute for Business & Home Safety (IBHS) is a nonprofit association that
engages in communication, education, engineering and research. The Institute
works to reduce deaths, injuries, property damage, economic losses and human
suffering caused by natural disasters.
Publications
"Land Use Planning for Earthquake Hazard Mitigation: Handbook for
Planners"
Wolfe, Myer R. et. a!., (1986) University of Colorado, Institute of Behavioral
Science, National Science Foundation.
This handbook provides techniques that planners and others can utilize
to help mitigate for seismic hazards, It provides information on the
effects of earthquakes, sources on risk assessment, and effects of
earthquakes on the built environment. The handbook also gives
examples on application and implementation of planning techniques to
be used by local communities.
Contact: Natural Hazards Research and Applications Information Center
Address: University of Colorado, 482 UCB,
Boulder, CO 80309-0482
Phone: (303) 492-6818
Fax: (303) 492-2151
Website: http://www.colorado.edu/UCB/Research/IBS/hazards
"Public Assistance Debris Management Guide", FEMA (July 2000).
The Debris Management Guide was developed to assist local officials in
planning, mobilizing, organizing. and controlling large-scale debris
clearance, removal, and disposal operations, Debris management is
generally associated with post-disaster recovery. While it should be
compliant with local and county emergency operations plans,
developing strategies to ensure strong debris management is a way to
integrate debris management within mitigation activities. The "Public
Assistance Debris Management Guide" is available in hard copy or on
the FEMA website.
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Website: http://www.fema.gov
End Notes
I. http://pubs.usgs.gov/gip/earthq3/when.html
II. http://www.gps.caltech.edu/...sieh/home.html
III. Planning for Natural Hazards: The California Technical Resource Guide,
Department of Land Conservation and Development (July 2000)
IV. Dolan et. aI., "Active Faults in the Los Angeles Metropolitan Region", Southern
California Earthquake Center Group C
V. http://www.data.scec.org/fault_index/monica.html
VI. http://www.consrv.ca.gov/CGS/rghm/ap/
VII. Ibid
VIII. Burby, R. (Ed.) Cooperating with Nature: Confronting Natural Hazards with
Land Use Planning for Sustainable Communities (1998), Washington D.C.,
Joseph Henry Press.
IX. FEMA HAZUS http://www.fema.gov/hazus/hazus2.htm (May 2001)
X. Institute for Business and Home Safety Resources (April 2001)
XI. http:j jwww.seismic.ca .govjpubjCSSC_200 1-04_Hospital. pdf
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2.2 landslide
Table of Contents
Why Are Landslides a Threat to City of Santa Monica________________________________________}9
History of Landslide Events and Impacts _______________________________________________________________}9
La n ds lid e Ch a racte ri sti cs __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ ___ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ ___ __ __ _____8 2
Hazard Identification
86
v u I n e ra b i I ity and Ri s k___ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ ___ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ ___ __ __ __ ___8 6
Com m unity La ndsl i de Issues ______________________________________________________________________________________87
La ndsl ide Resou rce Directory _____________________________________________________________________________________90
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Why are Landslides a Threat to City of Santa Monica
Landslides are a serious geologic hazard in almost every state in America.
Nationally, landslides cause 25 to 50 deaths each year.Xii The best estimate
of direct and indirect costs of landslide damage in the United States range
between $1 and $2 billion annually.Xiii As a seismically active region,
California has had significant number of locations impacted by landslides.
Some landslides result in private property damage, other landslides impact
transportation corridors, fuel and energy conduits, and communication
facilities. They can also pose a serious threat to human life.
Landslides can be broken down into two categories: (1) rapidly moving
(generally known as debris flows), and (2) slow moving. Rapidly moving
landslides or debris flows present the greatest risk to human life, and people
living in or traveling through areas prone to rapidly moving landslides are at
increased risk of serious injury. Slow moving landslides can cause significant
property damage, but are less likely to result in serious human injuries.
The topography of the City of Santa Monica is essentially flat and there is
little (or no) danger of landslide activity. However, the Palisades, located in
the northwest portion of the City, is a sheer cliff of fragile sandstone that
rises about 100 feet above the coast that separates the northern part of the
City from the beach below. As this area is susceptible to landslides,
mitigation projects have been enacted.
The City of Santa Monica does have liquefaction zones as indicated on Map
2.3. Since the settlement of the city in the 1800's, there have not (or have)
been any instances of liquefaction associated with seismic activity.
Historic Southern California Landslides
1928 St. Francis Dam failure
Los Angeles County, California. The dam gave way on March 12, and
its waters swept through the Santa Clara Valley toward the Pacific
Ocean, about 54 miles away. Sixty five miles of valley was devastated,
and over 500 people were killed. Damages were estimated at $672.1
million (year 2000 dollars).xiv
1956 Portuguese Bend, California
Cost, $14.6 million (2000 dollars) California Highway 14, Palos Verdes
Hills. Land use on the Palos Verdes Peninsula consists mostly of single-
family homes built on large lots, many of which have panoramic ocean
views. All of the houses were constructed with individual septic
systems, generally consisting of septic tanks and seepage pits.
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Landslides have been active here for thousands of years, but recent
landslide activity has been attributed in part to human activity. The
Portuguese Bend landslide began its modern movement in August
1956, when displacement was noticed at its northeast margin.
Movement gradually extended downslope so that the entire eastern
edge of the slide mass was moving within 6 weeks. By the summer of
1957, the entire slide mass was sliding towards the sea.xv
1958-1971 Pacific Palisades, California
Cost, $29.1 million (2000 dollars) California Highway 1 and house
damaged.xvi
1961 Mulholland Cut, California
Cost, $41.5 million (2000 dollars) On Interstate 405, 11 miles north of
Santa Monica, Los Angeles County.XVii
1963 Baldwin Hills Dam Failure.
On December 14, the 650 foot long by 155 foot high earth fill dam
gave way and sent 360 million gallons of water in a fifty foot high wall
cascading onto the community below, killing five persons, and
damaging $50 million (2000 dollars) of dollars in property.
1969 Glendora, California
Cost, $26.9 million (2000 dollars) Los Angeles County, 175 houses
damaged, mainly by debris flows.xviii
1969 Seventh Ave., Los Angeles County, California
Cost, $14.6 million (2000 dollars) California Highway 60.xix
1970 Princess Park, California
Cost, $29.1 million (2000 dollars) California Highway 14, 10 miles
north of Newhall, near Saugus, northern Los Angeles County.xx
1971 Upper and Lower Van Norman Dams, San Fernando,
California
Earthquake-induced landslides Cost, $302.4 million (2000 dollars).
Damage due to the February 9, 1971, magnitude 7.5 San Fernando,
California, earthquake. The earthquake of February 9 severely
damaged the Upper and Lower Van Norman Dams.xxi
1971 Juvenile Hall, San Fernando, California
Landslides caused by the February 9, 1971, San Fernando, California,
earthquake Cost, $266.6 million (2000 dollars). In addition to
damaging the San Fernando Juvenile Hall, this 1.2 km-Iong slide
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damaged trunk lines of the Southern Pacific Railroad, San Fernando
Boulevard, Interstate Highway 5, the Sylmar, California, electrical
converter station, and several pipelines and canals.xxii
1977-1980 Monterey Park, Repetto Hills, Los Angeles County,
California
Cost, $14.6 million (2000 dollars) 100 houses damaged in 1980 due to
debris flows.xxiii
1978 Bluebird Canyon Orange County
California October 2, cost, $52.7 million (2000 dollars) 60 houses
destroyed or damaged. Unusually heavy rains in March of 1978 may
have contributed to initiation of the landslide. Although the 1978 slide
area was approximately 3.5 acres, it is suspected to be a portion of a
larger, ancient landslide.xxiv
1979 Big Rock, California, Los Angeles County
Cost, approximately $1.08 billion (2000 dollars) California Highway 1
rockslide.xxv
1980 Southern California slides
$1.1 billion in damage (2000 dollars) Heavy winter rainfall in 1979-90
caused damage in six Southern California counties. In 1980, the
rainstorm started on February 8. A sequence of 5 days of continuous
rain and 7 inches of precipitation had occurred by February 14. Slope
failures were beginning to develop by February 15 and then very high-
intensity rainfall occurred on February 16. As much as 8 inches of rain
fell in a 6 hour period in many locations. Records and personal
observations in the field on February 16 and 17 showed that the
mountains and slopes literally fell apart on those 2 days.xxvi
1983 San Clemente, California, Orange County
Cost, $65 million (2000 dollars), California Highway 1. Litigation at
that time involved approximately $43.7 million (2000 dollars).xxvii
1983 Big Rock Mesa, California
Cost, $706 million (2000 dollars) in legal claims condemnation of 13
houses, and 300 more threatened rockslide caused by rainfall xxviii
1978-1979, 1980 San Diego County, California
Experienced major damage from storms in 1978, 1979, and 1979-80,
as did neighboring areas of Los Angeles and Orange County, California.
One hundred and twenty landslides were reported to have occurred in
San Diego County during these 2 years. Rainfall for the rainy seasons
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of 78-79 and 79-80 was 14.82 and 15.61 inches (37.6 and 39.6 cm)
respectively, compared to a 125-year average (1850-1975) of 9.71
inches (24.7 cm). Significant landslides occurred in the Friars
Formation, a unit that was noted as slide-prone in the Seismic Safety
Study for the City of San Diego. Of the nine landslides that caused
damage in excess of $1 million, seven occurred in the Friars
Formation, and two in the Santiago Formation in the northern part of
San Diego County.XXiX
1994 Northridge, California earthquake landslides
As a result of the magnitude 6.7 Northridge, California, earthquake,
more than 11,000 landslides occurred over an area of 10,000 km2.
Most were in the Santa Susana Mountains and in mountains north of
the Santa Clara River Valley. Destroyed dozens of homes, blocked
roads, and damaged oil-field infrastructure. Caused deaths from
Coccidioidomycosis (valley fever) the spore of which was released from
the soil and blown toward the coastal populated areas. The spore was
released from the soil by the landslide activity. xxx
March 1995 Los Angeles and Ventura Counties, Southern
California
Above normal rainfall triggered damaging debris flows, deep-seated
landslides, and flooding. Several deep-seated landslides were triggered
by the storms, the most notable was the La Conchita landslide, which
in combination with a local debris flow, destroyed or badly damaged
11 to 12 homes in the small town of La Conchita, about 20 km west of
Ventura. There also was widespread debris-flow and flood damage to
homes, commercial buildings, and roads and highways in areas along
the Malibu coast that had been devastated by wildfire 2 years
before. xxxi
LANDSLIDE CHARACTERISTICS
What is a landslide?
"A landslide is defined as, the movement of a mass of rock, debris, or earth
down a slope. Landslides are a type of "mass wasting" which denotes any
down slope movement of soil and rock under the direct influence of gravity.
The term "landslide" encompasses events such as rock falls, topples, slides,
spreads, and flows. Landslides can be initiated by rainfall, earthquakes,
volcanic activity, changes in groundwater, disturbance and change of a slope
by man-made construction activities, or any combination of these factors.
Landslides can also occur underwater, causing tidal waves and damage to
coastal areas. These landslides are called submarine landslides."xxxii
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The size of a landslide usually depends on the geology and the initial cause of
the landslide. Landslides vary greatly in their volume of rock and soil, the
length, width, and depth of the area affected, frequency of occurrence, and
speed of movement. Some characteristics that determine the type of
landslide are slope of the hillside, moisture content, and the nature of the
underlying materials. Landslides are given different names, depending on the
type of failure and their composition and characteristics.
Slides move in contact with the underlying surface. These movements
include rotational slides where sliding material moves along a curved surface,
and translational slides where movement occurs along a flat surface. These
slides are generally slow moving and can be deep. Slumps are small
rotational slides that are generally shallow. Slow-moving landslides can occur
on relatively gentle slopes and can cause significant property damage, but
are far less likely to result in serious injuries than rapidly moving
la ndsl ides. xxxiii
"Failure of a slope occurs when the force that is pulling the slope downward
(gravity) exceeds the strength of the earth materials that compose the slope.
They can move slowly, (millimeters per year) or can move quickly and
disastrously, as is the case with debris-flows. Debris-flows can travel down a
hillside of speeds up to 200 miles per hour (more commonly, 30 - 50 miles
per hour), depending on the slope angle, water content, and type of earth
and debris in the flow. These flows are initiated by heavy, usually sustained,
periods of rainfall, but sometimes can happen as a result of short bursts of
concentrated rainfall in susceptible areas. Burned areas charred by wildfires
are particularly susceptible to debris flows, given certain soil characteristics
and slope conditions. "xxxiv
What is a Debris Flow?
A debris or mud flow is a river of rock, earth and other materials, including
vegetation that is saturated with water. This high percentage of water gives
the debris flow a very rapid rate of movement down a slope. Debris flows
often with speeds greater than 20 mile per hour, and can often move much
faster.xxxv This high rate of speed makes debris flows extremely dangerous
to people and property in its path.
Landslide Events and Impacts
Landslides are a common hazard in California. Weathering and the
decomposition of geologic materials produces conditions conducive to
landslides and human activity further exacerbates many landslide problems.
Many landslides are difficult to mitigate, particularly in areas of large historic
movement with weak underlying geologic materials. As communities continue
to modify the terrain and influence natural processes, it is important to be
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aware of the physical properties of the underlying soils as they, along with
climate, create landslide hazards. Even with proper planning, landslides will
continue to threaten the safety of people, property, and infrastructure, but
without proper planning, landslide hazards will be even more common and
more destructive.
The increasing scarcity of build-able land, particularly in urban areas,
increases the tendency to build on geologically marginal land. Additionally,
hillside housing developments in Southern California are prized for the view
lots that they provide.
Rock falls occur when blocks of material come loose on steep slopes.
Weathering, erosion, or excavations, such as those along highways, can
cause falls where the road has been cut through bedrock. They are fast
moving with the materials free falling or bouncing down the slope. In falls,
material is detached from a steep slope or cliff. The volume of material
involved is generally small, but large boulders or blocks of rock can cause
significant damage.
Earth flows are plastic or liquid movements in which land mass (e.g. soil and
rock) breaks up and flows during movement. Earthquakes often trigger
flows.xxxvi Debris flows normally occur when a landslide moves downslope as
a semi-fluid mass scouring, or partially scouring soils from the slope along its
path. Flows are typically rapidly moving and also tend to increase in volume
as they scour out the channel.xxxvii Flows often occur during heavy rainfall,
can occur on gentle slopes, and can move rapidly for large distances.
Landslide Conditions
Landslides are often triggered by periods of heavy rainfall. Earthquakes,
subterranean water flow and excavations may also trigger landslides. Certain
geologic formations are more susceptible to landslides than others. Human
activities, including locating development near steep slopes, can increase
susceptibility to landslide events. Landslides on steep slopes are more
dangerous because movements can be rapid.
Although landslides are a natural geologic process, the incidence of landslides
and their impacts on people can be exacerbated by human activities. Grading
for road construction and development can increase slope steepness. Grading
and construction can decrease the stability of a hill slope by adding weight to
the top of the slope, removing support at the base of the slope, and
increasing water content. Other human activities effecting landslides include:
excavation, drainage and groundwater alterations, and changes in
vegetation. xxxviii
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Wildland fires in hills covered with chaparral are often a precursor to debris
flows in burned out canyons. The extreme heat of a wildfire can create a soil
condition in which the earth becomes impervious to water by creating a
waxy-like layer just below the ground surface. Since the water cannot be
absorbed into the soil, it rapidly accumulates on slopes, often gathering loose
particles of soil in to a sheet of mud and debris. Debris flows can often
originate miles away from unsuspecting persons, and approach them at a
high rate of speed with little warning.
Natural Conditions
Natural processes can cause landslides or re-activate historical landslide
sites. The removal or undercutting of shoreline-supporting material along
bodies of water by currents and waves produces countless small slides each
year. Seismic tremors can trigger landslides on slopes historically known to
have landslide movement. Earthquakes can also cause additional failure
(lateral spreading) that can occur on gentle slopes above steep streams and
riverbanks.
Particularly Hazardous Landslide Areas
Locations at risk from landslides or debris flows include areas with one or
more of the following conditions:
. On or close to steep hills;
. Steep road-cuts or excavations;
. Existing landslides or places of known historic landslides (such sites
often have tilted power lines, trees tilted in various directions, cracks
in the ground, and irregular-surfaced ground);
. Steep areas where surface runoff is channeled, such as below culverts,
V -shaped valleys, canyon bottoms, and steep stream channels; and
. Fan-shaped areas of sediment and boulder accumulation at the outlets
of canyons.
. Canyon areas below hillside and mountains that have recently (within
1-6 years) been subjected to a wildland fire.
Impacts of Development
Although landslides are a natural occurrence, human impacts can
substantially affect the potential for landslide failures in the City of Santa
Monica. Proper planning and geotechnical engineering can be exercised to
reduce the threat of safety of people, property, and infrastructure.
Excavation and Grading
Slope excavation is common in the development of home sites or roads on
sloping terrain. Grading these slopes can result in some slopes that are
steeper than the pre-existing natural slopes. Since slope steepness is a major
factor in landslides, these steeper slopes can be at an increased risk for
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landslides. The added weight of fill placed on slopes can also result in an
increased landslide hazard. Small landslides can be fairly common along
roads, in either the road cut or the road fill. Landslides occurring below new
construction sites are indicators of the potential impacts stemming from
excavation.
Drainage and Groundwater Alterations
Water flowing through or above ground is often the trigger for landslides.
Any activity that increases the amount of water flowing into landslide-prone
slopes can increase landslide hazards. Broken or leaking water or sewer lines
can be especially problematic, as can water retention facilities that direct
water onto slopes. However, even lawn irrigation in landslide prone locations
can result in damaging landslides. Ineffective storm water management and
excess runoff can also cause erosion and increase the risk of landslide
hazards. Drainage can be affected naturally by the geology and topography
of an area; Development that results in an increase in impervious surface
impairs the ability of the land to absorb water and may redirect water to
other areas. Channels, streams, ponding, and erosion on slopes all indicate
potential slope problems.
Road and driveway drains, gutters, downspouts, and other constructed
drainage facilities can concentrate and accelerate flow. Ground saturation
and concentrated velocity flow are major causes of slope problems and may
trigger landslides. xxxix
Changes in Vegetation
Removing vegetation from very steep slopes can increase landslide hazards.
Areas that experience wildfire and land clearing for development may have
long periods of increased landslide hazard. Also, certain types of ground
cover have a much greater need for constant watering to remain green.
Changing away from native ground cover plants may increase the risk of
landslide.
LANDSLIDE HAZARD ASSESSMENT
Hazard Identification
Identifying hazardous locations is an essential step towards implementing
more informed mitigation activities. Insert here any efforts being made
to map slide or potential slide areas. Briefly describe those projects
and the effects/impacts that they may have on mitigating landslide
hazards.
Vulnerability and Risk
Vulnerability assessment for landslides will assist in predicting how different
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types of property and population groups will be affected by a hazard.xl Data
that includes specific landslide-prone and debris flow locations in the city can
be used to assess the population and total value of property at risk from
future landslide occurrences.
While a quantitative vulnerability assessment (an assessment that describes
number of lives or amount of property exposed to the hazard) has not yet
been conducted for the City of Santa Monica landslide events, there are
many qualitative factors that point to potential vulnerability. Landslides can
impact major transportation arteries, blocking residents from essential
services and businesses.
Past landslide events have caused major property damage or significantly
impacted city residents, and continuing to map city landslide and debris flow
areas will help in preventing future loss. Factors included in assessing
landslide risk include population and property distribution in the hazard area,
the frequency of landslide or debris flow occurrences, slope steepness, soil
characteristics, and precipitation intensity. This type of analysis could
generate estimates of the damages to the city due to a specific landslide or
debris flow event. At the time of publication of this plan, data was
insufficient to conduct a risk analysis and the software needed to conduct this
type of analysis was not available.
COMMUNITY LANDSLIDE ISSUES
What is Susceptible to Landslides?
Landslides can affect utility services, transportation systems, and critical
lifelines. Communities may suffer immediate damages and loss of service.
Disruption of infrastructure, roads, and critical facilities may also have a
long-term effect on the economy. Utilities, including potable water,
wastewater, telecommunications, natural gas, and electric power are all
essential to service community needs. Loss of electricity has the most
widespread impact on other utilities and on the whole community. Natural
gas pipes may also be at risk of breakage from landslide movements as small
as an inch or two.
Roads and Bridges
Losses incurred from landslide hazards in the City of Santa Monica have been
associated with roads, specifically the Pacific Coast Highway. The City of
Santa Monica Roads Division is responsible for responding to slides that
inhibit the flow of traffic or are damaging a road or a bridge. The roads
department does its best to communicate with residents impacted by
landslides, but can usually only repair the road itself, as well as the areas
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adjacent to the slide where the city has the right of way.
It is not cost effective to mitigate all slides because of limited funds and the
fact that some historical slides are likely to become active again even with
mitigation measures. The city Roads Division alleviates problem areas by
grading slides, and by installing new drainage systems on the slopes to divert
water from the landslides. This type of response activity is often the most
cost-effective in the short-term, but is only temporary. Unfortunately, many
property owners are unaware of slides and the dangers associated with
them.
Lifelines and critical facilities
Lifelines and critical facilities should remain accessible, if possible, during a
natural hazard event. The impact of closed transportation arteries may be
increased if the closed road or bridge is critical for hospitals and other
emergency facilities. Therefore, inspection and repair of critical
transportation facilities and routes is essential and should receive high
priority. Losses of power and phone service are also potential consequences
of landslide events. Due to heavy rains, soil erosion in hillside areas can be
accelerated, resulting in loss of soil support beneath high voltage
transmission towers in hillsides and remote areas. Flood events can also
cause landslides, which can have serious impacts on gas lines that are
located in vulnerable soils.
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Landslide Resource Directory (See details in Appendix A)
Cou nty Resou rces
· Los Angeles County Department of Public Works
State Resources
· Department of Conservation Headquarters
· California Geological Survey HeadquartersjOffice of the State Geologist
· California Division of Forestry
· Department of Water Resources
. Governor's Office of Emergency Services
· California Department of Transportation (Cal Trans)
Federal Resources and Programs
· Federal Emergency Management Agency (FEMA)
· Natural Resource Conservation Service (NRCS)
· US Geological Survey, National Landslide Information Center
Publications
Olshansky, Robert B., Planninq for Hillside Development (1996) American
Planning Association.
This document describes the history, purpose, and functions of hillside
development and regulation and the role of planning, and provides
excerpts from hillside plans, ordinances, and gUidelines from
communities throughout the US.
Olshansky, Robert B. & Rogers, J. David, Unstable Ground: Landslide PolicY
in the United States (1987) Ecology Law Quarterly.
This is about the history and policy of landslide mitigation in the US.
Public Assistance Debris Manaqement Guide (July 2000) Federal Emergency
Management Agency.
The Debris Management Guide was developed to assist local officials in
planning, mobilizing, organizing, and controlling large-scale debris clearance,
removal, and disposal operations. Debris management is generally
associated with post-disaster recovery. While it should be compliant with
local and city emergency operations plans, developing strategies to ensure
strong debris management is a way to integrate debris management within
mitigation activities. The Guide is available in hard copy or on the FEMA
website.
USGS Landslide Proqram Brochure. National Landslide Information Center
(NLIC), United States Geologic Survey.
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The brochure provides good, general information in simple terminology on
the importance of landslide studies and a list of databases, outreach, and
exhibits maintained by the NLLC. The brochure also includes information on
the types and causes of landslides, rock falls, and earth flows.
Landslide Endnotes
I. 1. Mileti, Dennis, Disasters by Design: A Reassessment of Natural Hazards in
the United States (1999) Joseph Henry Press, Washington D.C.
II. 1. Brabb, E.E., and B.L Harrod. (Eds) Landslides: Extent and Economic
Significance. Proceedings of the 28th International Geological Congress
Symposium on Landslides. (1989) Washington D.C., Rotterdam: Balkema.
III. 1. Highland, L.M., and Schuster, R.L., Significant Landslide Events in the
United States. (No Date) USGS, Washington D.C.,
http://landslides. usgs. gov. html_fi lesjpubsjreport1jLa ndsl ides_pass_508. pdf
IV. 1. Ibid.
V. 1. Ibid.
VI. 1. Ibid.
VII. 1. Ibid.
VIII. 1. Ibid.
IX. 1. Ibid.
X. 1. Ibid.
XI. 1. Ibid.
XII. 1. Ibid.
XIII. 1. Ibid.
XIV. 1. Ibid.
XV. 1. Ibid.
XVI. 1. Ibid.
XVII. 1. Ibid.
XVIII. 1. Ibid.
XIX. 1. Ibid.
XX. 1. Ibid.
XXI. 1. Landslide Hazards, U.s. Geological Survey Fact Sheet 0071-00, Version
1.0, U.S. Department of the Interior - U.s. Geological Survey,
htto:/ /oubs. USQs.qov/fs/fs-0071-00/
XXII. 1. Interagency Hazard Mitigation Team, State Hazard Mitigation Plan (2000)
Oregon Emergency Management
XXIII. 1. Ibid.
XXIV. 1. Barrows, Alan and Smith, Ted, DMG Note 13,
http:j jwww.consrv.ca .govj cgsjinformationjpublicationsj cgs_notesjnote_33j
XXV. 1. Robert Olson Associates, Metro Regional Hazard Mitigation and Planning
Guide (June 1999) Metro
XXVI. 1. Ibid.
XXVII. 1. Planning For Natural Hazards: The Oregon Technical Resource Guide,
Department of Land Conservation and Development (2000), Ch 5.
XXVIII. 1. Homeowners Guide for Landslide Control, Hillside Flooding, Debris Flows,
Soil Erosion, (March 1997)
XXIX. 1. Burby, R. (Ed.) Cooperating With Nature (1998) Washington, D.C.:
Joseph Henry Press.
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2.3 Flood
Table of Contents
Why Are Floods a Threat to the City of Santa Monica __________________________________ 93
History of Floodi ng in the Southern Ca I iforn ia Region_________________________________ 9 5
What Factors Create Flood Risk?
100
Flood Term i no logy . _ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ ___ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __.103
Cha racteristics of Flood i ng ________________________________________________________________________________104
Hazard Identification
108
Ri s k A n a I ys is. __ __ ___ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ ___ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __.109
Vu I nera bi I ity Assessme nt__________________________________________________________________________________1 09
Com m unity Flood Issues ___________________________________________________________________________________.109
Flood Resou rce Directory ___________________________________________________________________________________.113
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Why are Floods a Threat to the City of Santa Monica
Santa Monica is designated by the National Flood Insurance Program as a
Zone "C", or City of minimal flood hazard. The hazardous situations caused
by storms are generally dependent on the amount of warning time that the
City receives prior to an actual disaster. Monitoring of storms by weather
services have historically provided warning times that can vary from weeks
to hours prior to the event. The ability of City personnel to conduct an
evacuation, provide sandbagging, and perform other mitigative measures is
dependent on the amount of warning time that the City receives from
weather services.
The City of Santa Monica is familiar with the flooding and destruction caused
by astronomical tides and heavy storm conditions. During the winter of 1983,
the City suffered a major loss to the Pier facility. Most of the west end of the
Pier and the section under Pacific Park was rebuilt with concrete pilings and
caps following the 1983 storm. Again, in 1988, additional storm damage was
sustained. In 1998, the EI Nino Storms created approximated $400,000 in
flood damage and recurring landslides along Palisades Park blocking Pacific
Coast Highway. The landslide was approximately 115 feet high and 150 feet
wide. Sloughing affected the stability of the near vertical bluff. Mitigation
measures of drilling vertically and horizontally into the hillside assisted in
removing water from bluff and grading the top and bottom of the bluff
reduced the threat to life and property.
There are a number of rivers in the Southern California region, but the river
with the best recorded history is the Los Angeles River. The flood history of
the Los Angeles River is generally indicative of the flood history of much of
Southern California.
The Los Angeles County Drainage Area comprises a 1,459 square mile
watershed which flows to the Pacific Ocean mainly through the Los Angeles
River and the San Gabriel River. The Los Angeles River is approximately 55
miles long and has an aggregate tributary system which is 225 miles in
length. Stream slopes range from extremely steep, 200 feet per mile or
more in the mountains, to about three feet per mile over the coastal plain.
Due to steep terrain, runoff from the mountains concentrates quickly. Runoff
from urban watersheds is generally uncontrolled and is characterized by high
flood peaks of short durations, because a high percentage of the rain falls on
impervious cover. Los Angeles area flood events are typically of less than
twelve hour durations. The lower Los Angeles River will respond to heavy
rain by rising from 2/3 channel capacity to full in less than an hour, and
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reversing to 2/3 channel capacity within two hours. Such events have been
noted recently, in 1980, 1993 and 1995.
Through historic times, and as evidenced in a variety of pre-historic sources,
the Los Angeles area has been periodically pounded by heavy rains and
inundated by floods. Some of the heaviest rains ever recorded on the west
coast of North America occurred near Los Angeles as a result of the high
transverse orographic barrier catching a moist subtropical airflow. Historical
references highlight eight major floods across the coastal plain in the Los
Angeles area between 1815 and 1876. From 1884 to 1938, nine more floods
wreaked havoc. In the latter half of the twentieth century, enormous public
work projects were completed which served to mitigate flood damage in the
Los Angeles area.
Prior to 1915, little was done to control flooding within the county. To the
contrary, uncontrolled growth and economic development did much to
exacerbate a growing urban flood problem, which in fact had become one of
the worst in the United States.
Through the early twentieth century, the Los Angeles River, at 55 miles long,
was the county's major (and most capricious) drainage. The Los Angeles
River had a long history of meandering almost at random across the coastal
plain, emptying into the Pacific Ocean at various places from Santa Monica to
Long Beach.
Flood destruction and loss of life awakened the growing population of the Los
Angeles Basin to the need for flood control. The Los Angeles County Flood
Control District was established in 1915, and Congress authorized the U.S.
Army Corps of Engineers to work on the Los Angeles River problem at about
the same time.
The river posed major difficulties: An intermittent and swampy slough in the
late summer, it became an unpredictable and raging torrent during periods of
heavy rain. In flood stage, the river was gorged with huge volumes of water,
strong current velocities, large debris loads, and unstable channels. As the
population of the Los Angeles area grew rapidly in the early twentieth
century, each flood produced increasing damage to the district, and scores of
lives were lost. Flood control had become absolutely essential.
Between 1917 and 1965, the huge public works projects undertaken by the
Corps of Engineers and its partners bore fruit. With great leaps forward in
technology and in ecological sensitivity, a series of catchment basins and
concrete or stone-lined channels controlled the Los Angeles River, its
tributaries, and other streams within the district. The cost was high - over
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two billion dollars in federal and local funds for the entire project - but great
benefits were realized. There were no more catastrophic floods after the
1950s, in spite of the sharp upward trend in urbanization and an increase in
the number of heavy rainfall events late in the century. In addition, valuable
recreation land was set aside for the public trust as a result of construction of
catchment basins along channels.
The last major flood destruction in Los Angeles occurred on March 2, 1938.
Forty-nine lives were lost. A major rainfall event occurred in 1969, in which
an estimated $1.5 billion in damage was saved by flood control projects.
Other heavy rains in 1983, 1992 and 1998 were well-handled by the complex
system of drainages, catchments and bridges built by the Corps of Engineers
within the Los Angeles area.
The current Los Angeles County Drainage Area flood control system is one of
the world's largest and most extensive flood protection infrastructures. This
flood protection includes:
15 flood control reservoirs
5 flood control basins
143 debris control basins
225 stabilization dams
33 storm water pumping plants
470 miles of open, improved channel
2,400 miles of underground drains
75,000 catch basins
The Corps of Engineers estimates that the value of damages prevented by
the system in storms during its lifetime has already reached $3.6 billion.
Projects now underway in the lower Los Angeles River will expand the
channel capacity from 133,000 cubic feet per second (cfs) to 182,000 cfs,
which would approximate a 133-year flood (Plates 1-5). (Attached to text).
Heavy rain still poses a flooding threat in the Los Angeles Basin, but the
greatest problems are now associated with urban flooding, ponding of water
in poorly drained areas, and high outflow of water, mud and debris below
canyons draining higher terrain.
Historic Flooding in Los Angeles County
Records show that since 1811, the Los Angeles River has flooded 30 times,
on average once every 6.1 years. But averages are deceiving, for the Los
Angeles basin goes through periods of drought and then periods of above
average rainfall. Between 1889 and 1891 the river flooded every year, and
from 1941 to 1945, the river flooded 5 times. Conversely, from 1896 to
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1914, a period of 18 years, and again from 1944 to 1969, a period of 25
years, the river did not have serious floods.l
T bl 22M" FI d f th L A R"
a e . a]or 00 so e os nge es Iver
1811 Flooding
1815 Flooding
1825 River changed its course back from the Ballona wetlands to San
Ped ro
1832 Heavy flooding
1861-62 Heavy flooding. Fifty inches of rain falls during December and
January.
1867 Floods create a larqe, temporary lake out to Ballona Creek.
1876 The Novician Deluge
1884 Heavy flooding causes the river to change course again, turning
east to Vernon and then southward to San Pedro.
1888- Annual floods
1891
1914 Heavy flooding. Great damage to the harbor.
1921 Floodinq
1927 Moderate flood
1934 Moderate flood starting January 1. Forty dead in La Canada.
1938 Great County-wide flood with 4 days of rain. Most rain on day 4.
1941-44 L.A. River floods five times.
1952 Moderate flooding
1969 One heavy flood after 9 day storm. One moderate flood.
1978 Two moderate floods
1979 Los Angeles experiences severe flooding and mudslides.
1980 Flood tops banks of river in Long Beach. Sepulveda Basin spillway
almost opened.
1983 Floodinq kills six people.
1992 15 year flood. Motorists trapped in Sepulveda basin. Six people
dead.
1994 Heavy floodinq
Sources: http://www.lalc. k12.ca. us/target/units/river/tour/hist. html and
(http:/ /www.losangelesalmanac.com/topics/History/hiOli.htm)
Flooding in the Los Angeles Basin was mentioned by Spanish missionaries as
early as the eighteenth century. But from the time of the establishment of
the civil settlement at Los Angeles in 1781 until the second decade of the
nineteenth century, rainfall rates were remarkably low in the area. Then in
1815, a massive flood cut a channel across what is now the downtown
district, re-routing the Los Angeles River westward, where it emptied into the
Pacific Ocean south of Santa Monica, at Ballona Lagoon. A decade later, an
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1825 storm returned the Los Angeles River to its present channel, which now
flows southward into the Pacific Ocean at San Pedro Bay.
From December 24, 1861 to January 31, 1862 almost continuous heavy
rainfall deluged all of California. Heaviest rains were recorded at San
Francisco - which averaged almost an inch of rain per day for 30 days, in
what was computed to be a 37,000 year event (Goodridge, 1997). In Los
Angeles, measurable rain occurred on thirty consecutive days. Flooding and
massive mudslides occurred throughout Los Angeles County, destroying
property and roadways.
Immediately following the flooding, in the fall of 1862, a severe drought
settled into Los Angeles County. No significant rains fell again in Los Angeles
until the fall of 1864. This drought doomed the embryonic cattle and
livestock industry within the basin.
Almost 26 inches of rain fell at Los Angeles in February and March 1884. The
1883-84 rainfall season was the wettest in recorded history, with 38.18
inches recorded downtown. There was some loss of life in the February and
March floods, and a great deal of property damage. Fifty houses were
washed away in floods.
The heavy rains of January 25-26, 1914 were followed by a second and
larger storm three weeks later. Large areas of the basin were flooded by the
Los Angeles River,. This flooding led directly to the establishment of the Los
Angeles County Flood Control District in 1915.
In January 1916 Los Angeles was on the northern fringe of the storm that
drenched San Diego County with its all-time record rainfalls. Los Angeles
was spared the worst of the disaster, but still received nearly eleven inches
of rain between January 14th and 28th, and widespread flooding occurred
within the district.
Beginning December 31, 1933 and continuing into New Year's Day 1934,
very heavy rains caused destructive flooding and mudslides across Los
Angeles County from Malibu to Covina. Fourteen weather stations in the Los
Angeles area reported record maximum two-day rainfalls, with two locations
recording l,OOO-year events. A rain gauge located on the slopes below
Mount Wilson recorded almost fifteen inches of rain on New Year's Day.
Glendale and Montrose - along the La Crescenta delta cone northwest of
Pasadena - were severely affected by a huge debris flow. The effect of the
heavy canyon outflows of mud, debris and boulders was exacerbated by a
fire which had burned over the district during the previous summer. In all,
the flooding left more than forty persons dead and destroyed or damaged
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500 homes. The City of Pasadena measured 6.21 inches of rain on that New
Year's Day in 1934, but the Tournament of Roses Parade went ahead as
scheduled.
The storm of March 2, 1938 produced another astounding precipitation and
flooding event in Los Angeles County. This flood was the most destructive
and violent of the twentieth century. Leading up to the March rains, Los
Angeles had received about ten inches of rain in February. On March 2nd,
with the ground already saturated, five to seven inches of rain fell across the
basin. Rainfall in the surrounding mountains was much heavier. Seventeen
mountain gauges recorded ten inches or more of rain, with a few receiving
up to 18 inches. Stream flows recorded by gauging stations within the San
Gabriel Mountain watershed were phenomenal. Forty-nine persons were
killed and millions of dollars of destruction was reported.
Less than five years later, in 1943, it rained extremely hard on January 22nd
and 23rd. The greatest 24-hour rainfall in California history occurred in this
storm when 26.12 inches fell at Hoegees, below Mount Wilson. Fifteen
weather stations in the transverse ranges received storm totals exceeding
twenty inches - Hoegees had a storm total of 36.34 inches - while many
more stations in the foothills and valleys of Los Angeles County reported a
one hundred-year event. Goodridge (1998) stated that the area
encompassing a 100-year or more return period covered 11,000 square
miles, and extended from Santa Barbara County to Riverside County.
Southern California received heavy precipitation through the 1968-69
season, particularly during January and February, when almost 23 inches of
rain fell at downtown Los Angeles. A low pressure trough had anchored off
the southern California coast, setting up a steady-state subtropical moisture
flow across the district. During this event, almost three hundred rain gauges
recorded the highest-ever 60-day rainfall totals.
Flood control projects completed before 1968 mitigated property damage in
Los Angeles. When the 1969 E/ Nino rains finally ended, Frank G. Bonelli of
the Los Angeles County Board of Supervisors stated that "the overall flood
control system prevented one of the worst catastrophes in the history of Los
Angeles." To the north, across Santa Barbara County and San Luis Obispo
County, losses and damage from these heavy rains had been much more
severe.
In the month of February 1980, thirteen inches of rain fell after an
abnormally wet January. The Los Angeles River slightly overflowed the
levees at the lower end of the river at Wardlow Road. The 129,000 cfs river
gauge measurement at that location was the highest recorded since records
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began in 1928. This 40-year flood event broke through a barrier that was
supposed to withstand a 100-year flood, which caused the Corps of
Engineers to re-evaluate flood protection for the lower Los Angeles River.
The January 4, 1995 storm caused about six million dollars damage, mostly
as a result of urban flooding from record rainfalls in the south portion of the
Los Angeles Basin. Between 3:00 and 4:30 p.m. on January 4th, the area in
south Los Angeles County between Long Beach and Carson was deluged with
up to 3.40 inches of rain, while a gauge near LAX received only 0.12 inches
and the Pomona area reported 0.55 inches. Two hundred structures were
flooded and one hundred vehicles abandoned. Flood control facilities
operated at peak capacity at many locations for short periods of time during
the event, but the Los Angeles River did not approach capacity because
intense rainfall occurred over only a relatively small portion of the lower
drainage basin.
In 1998, another strong EI Nino episode produced the wettest February of all
time at downtown Los Angeles, with 13.68 inches recorded during the month.
Over nineteen inches fell at Montebello Fire Station, just east of the
downtown weather station. In the Los Angeles metropolitan area, seasonal
rainfall records were established at six key area stations, including
Chatsworth with an incredible 44.19 inches. For the entire 1997-98 rainfall
season, precipitation over the whole district averaged a whopping 230% of
normal. With such huge numbers, it was somewhat surprising to note that
the only flooding reported was of the urban and small stream variety-more
nuisance than disaster. Several reasons are offered to explain the lack of
problems associated with this very heavy rainfall season:
. Ample warning, well in advance, of the strong probability of heavy
winter rains was provided by the National Weather Service and the
media. This prompted extra vigilance in the removal of debris from
storm basins and flood channels. When rains did occur, the National
Weather Service, using latest technologies, communicated warnings to
emergency officials. This, in turn, led to appropriate action-response.
. The rains were spread fairly evenly over the course of the 1997-1998
season.
Adequate long-term flood control measures by the U.S. Army Corps of
Engineers and their partners were largely completed and in place.
The towering mountains that give the Los Angeles region its spectacular
views also wring a great deal of rain out of the storm clouds that pass
through. Because the mountains are so steep, the rainwater moves rapidly
down the slopes and across the coastal plains on its way to the ocean.
"The Santa Monica, Santa Susana and Verdugo mountains, which
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surround three sides of the valley seldom reach heights above three
thousand feet. The western San Gabriel Mountains, in contrast, have
elevations of more than seven thousand feet. These higher ridges
often trap eastern-moving winter storms. Although downtown Los
Angeles averages just fifteen inches of rain a year, some mountain
peaks in the San Gabriels receive more than forty inches of
precipitation annually"2
Naturally, this rainfall moves rapidly down stream, often with severe
consequences for anything in its path. In extreme cases, flood-generated
debris flows will roar down a canyon at speeds near 40 miles per hour with a
wall of mud, debris and water tens of feet high. In Southern California,
stories of floods, debris flows, persons buried alive under tons of mud and
rock and persons swept away to their death in a river flowing at thirty-five
miles an hour are without end. No catalog of chaos could contain all the
losses suffered by man and his possessions from the regions rivers and
streams.
What Factors Create Flood Risk?
Flooding occurs when climate, geology, and hydrology combine to create
conditions where water flows outside of its usual course.
Winter Rainfall
Over the last 125 years, the average annual rainfall in Los Angeles is 14.9
inches. But the term "average" means very little as the annual rainfall during
this time period has ranged from only 4.35 inches in 2001-2002 to 38.2
inches in 1883-1884. In fact, in only fifteen of the past 125 years, has the
annual rainfall been within plus or minus 10% of the 14.9 inch average. And
in only 38 years has the annual rainfall been within plus or minus 20% of the
14.9 inch average. This makes the Los Angeles basin a land of extremes in
terms of annual precipitation.
Monsoons
Another relatively regular source for heavy rainfall, particularly in the
mountains and adjoining cities is from summer tropical storms. Table xxx
lists tropical storms that have had significant rainfall in the past century, and
the general areas affected by these storms. These tropical storms usually
coincide with EI Nino years.
Table 2.3 Tropical cyclones that have affected Southern California
during the 20th Century
Month- Date(s) Area (s) Affected Rainfall
Year
July 1902 20-21 Deserts & Southern up to 2"
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Mountains
Aug. 1906 18-19 Deserts & Southern up to 5"
Mountains
Sept. 15 Mountains of Santa Barbara 2"
1910 County
Aug. 1921 20-21 Deserts & Southern up to 2"
Mountains
Sept. 30 Deserts up to 4"
1921
Sept. 18 Southern Mountains & up to 4"
1929 Deserts
Sept. 28-0ct Mountains & Deserts, 15 up to 7
1932 1 Fata I iti es
Aug. 1935 25 Southern Valleys, Mountains up to 2"
& Deserts
Sept. 4-7 Southern Mountains, up to 7
1939 Southern & Eastern Deserts
11-12 Deserts, Central & Southern up to 4"
Mountains
19- 21 Deserts, Central & Southern up to 3"
Mountains
25 Long Beach, W/ Sustained 5"
Winds of 50 Mph
Surrounding Mountains 6 to 12"
Sept. 9-10 Central & Southern Mountains up to 2"
1945
Sept. 30-0ct Southern Mountains up to 4"
1946 1
Aug. 1951 27-29 Southern Mountains & 2 to 5"
Deserts
Sept. 19- 21 Central & Southern Mountains up to 2"
1952
July 1954 17-19 Deserts & Southern up to 2"
Mountains
July 1958 28-29 Deserts & Southern up to 2"
Mountains
Sept. 9-10 Julian 3.40"
1960
Sept. 17-19 Central & Southern Mountains up to 7"
1963
Sept. 1-3 Southern Mountains & 2"
1967 Deserts
Oct. 1972 6 Southeast Deserts up to 2"
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Sept. 10-11 Central & Southern 6 to 12"
1976 Mountains.
Aug. 1977 n/a Los Angeles 2"
Mountains up to 8"
Oct. 1977 6-7 Southern Mountains & up to 2"
Deserts
Sept. 5-6 Mountains 3"
1978
Sept. 24- 26 Mountains up to 4"
1982
Sept. 20-21 Southern Mountains & up to 3"
1983 Deserts
http://www.fema.gov/nwz97 /eln_scal.shtm
Geography and Geology
The greater Los Angeles Basin is the product of rainstorms and erosion for
millennia. "Most of the mountains that ring the valleys and coastal plain are
deeply fractured faults and, as they (the mountains) grew taller, their brittle
slopes were continually eroded. Rivers and streams carried boulders, rocks,
gravel, sand, and silt down these slopes to the valleys and coastal plain....In
places these sediments are as much as twenty thousand feet thick"3
Much of the coastal plain rests on the ancient rock debris and sediment
washed down from the mountains. This sediment can act as a sponge,
absorbing vast quantities of rain in those years when heavy rains follow a dry
period. But like a sponge that is near saturation, the same soil fills up rapidly
when a heavy rain follows a period of relatively wet weather. So even in
some years of heavy rain, flooding is minimal because the ground is
relatively dry. The same amount of rain following a wet period of time can
cause extensive flooding.
The greater Los Angeles basin is for all intents and purposes built out. This
leaves precious little open land to absorb rainfall. This lack of open ground
forces water to remain on the surface and rapidly accumulate. If it were not
for the massive flood control system with its concrete lined river and stream
beds, flooding would be a much more common occurrence. And the tendency
is towards even less and less open land. In-fill building is becoming a much
more common practice in many areas. Developers tear down an older home
which typically covers up to 40% of the lot size and replacing it with three or
four town homes or apartments which may cover 90-95% of the lot.
Another potential source of flooding is "asphalt creep." The street space
between the curbs of a street is a part of the flood control system. Water
leaves property and accumulates in the streets, where it is directed towards
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the underground portion of the flood control system. The carrying capacity of
the street is determined by the width of the street and the height of the
curbs along the street. Often, when streets are being resurfaced, a one to
two inch layer of asphalt is laid down over the existing asphalt. This added
layer of asphalt subtracts from the rated capacity of the street to carry
water. Thus the original engineered capacity of the entire storm drain system
is marginally reduced over time. Subsequent re-paving of the street will
further reduce the engineered capacity
even more.
FLOOD TERMINOLOGY
Floodplain
A floodplain is a land area adjacent to a river, stream, lake, estuary, or other
water body that is subject to flooding. This area, if left undisturbed, acts to
store excess flood water. The floodplain is made up of two sections: the
floodway and the flood fringe.
100-Year Flood The 100-year flooding event is the flood having a one percent
chance of being equaled or exceeded in magnitude in any given year.
Contrary to popular belief, it is not a flood occurring once every 100 years.
The 100-year floodplain is the area adjoining a river, stream, or watercourse
covered by water in the event of a 100-year flood.
Floodway
The floodway is one of two main sections that make up the floodplain.
Floodways are defined for regulatory purposes. Unlike floodplains, floodways
do not reflect a recognizable geologic feature. For N FIP purposes, floodways
are defined as the channel of a river or stream, and the overbank areas
adjacent to the channel. The floodway carries the bulk of the flood water
downstream and is usually the area where water velocities and forces are the
greatest. NFIP regulations require that the floodway be kept open and free
from development or other structures that would obstruct or divert flood
flows onto other properties.
The N FIP floodway definition is "the channel of a river or other watercourse
and adjacent land areas that must be reserved in order to discharge the base
flood without cumulatively increasing the water surface elevation more than
one foot.
Flood Fringe
The flood fringe refers to the outer portions of the floodplain, beginning at
the edge of the floodway and continuing outward.
Base Flood Elevation (BFE)
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The term "Base Flood Elevation" refers to the elevation (normally measured
in feet above sea level) that the base flood is expected to reach. Base flood
elevations can be set at levels other than the 100-year flood. Some
communities choose to use higher frequency flood events as their base flood
elevation for certain activities, while using lower frequency events for others.
For example, for the purpose of storm water management, a 25-year flood
event might serve as the base flood elevation; while the 500-year flood
event may serve as base flood elevation for the tie down of mobile homes.
The regulations of the NFIP focus on development in the 100-year floodplain.
Characteristics of Flooding
Urban Flooding
As land is converted from fields or woodlands to roads and parking lots, it
loses its ability to absorb rainfall. Urbanization of a watershed changes the
hydrologic systems of the basin. Heavy rainfall collects and flows faster on
impervious concrete and asphalt surfaces. The water moves from the clouds,
to the ground, and into streams at a much faster rate in urban areas. Adding
these elements to the hydrological systems can result in flood waters that
rise very rapidly and peak with violent force.
Dam Failure Flooding
Loss of life and damage to structures, roads, and utilities may result from a
dam failure. Economic losses can also result from a lowered tax base and
lack of utility profits. These effects would certainly accompany the failure of
one of the major dams in the City of Santa Monica. Because dam failure can
have severe consequences, FEMA requires that all dam owners develop
Emergency Action Plans (EAP) for warning, evacuation, and post-flood
actions. Although there may be coordination with county officials in the
development of the EAP, the responsibility for developing potential flood
inundation maps and facilitation of emergency response is the responsibility
of the dam owner. For more detailed information regarding dam failure
flooding, and potential flood inundation zones for a particular dam in the
county, refer to the the City of Santa Monica Emergency Action Plan.
There have been a total of 45 dam failures in California, since the 19th
century. The significant dam failures in Southern California are listed in Table
xxx.
Table 2.4 Dam Failures in Southern California
Sheffield Santa Barbara 1925 Earthquake slide
Puddingstone Pomona 1926 Overtopping during construction
Lake Hemet Palm Springs 1927 Overtoppi ng
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Saint Francis San 1928 Sudden failure at full capacity
Francisquito through foundation, 426 deaths
Canyon
Cogswell Monrovia 1934 Breaching of concrete cover
Baldwin Hills Los Angeles 1963 Leak through embankment turned
into washout, 3 deaths
http://cee.engr.ucdavis.edu/faculty/lund/dams/Dam_History_Page/Failu res. htm
The two most significant dam failures are the St. Francis Dam in 1928 and
the Baldwin Hills Dam in 1963. "The failure of the St. Francis Dam, and the
resulting loss of over 500 lives in the path of a roaring wall of water, was a
scandal that resulted in the almost complete destruction of the reputation of
its builder, William Mulholland. Mulholland was an immigrant from Ireland
who rose up through the ranks of the city's water department to the position
of chief engineer. It was he who proposed, designed, and supervised the
construction of the Los Angeles Aqueduct, which brought water from the
Owens Valley to the city. The St. Francis Dam, built in 1926, was 180 feet
high and 600 feet long; it was located near Saugus in the San Francisquito
Canyon. The dam gave way on March 12, 1928, three minutes before
midnight. Its waters swept through the Santa Clara Valley toward the Pacific
Ocean, about 54 miles away. 65 miles of valley was devastated before the
water finally made its way into the ocean between Oxnard and Ventura. At its
peak the wall of water was said to be 78 feet high; by the time it hit Santa
Paula, 42 miles south of the dam, the water was estimated to be 25 feet
deep. Almost everything in its path was destroyed: livestock, structures,
railways, bridges, and orchards. By the time it was over, parts of Ventura
County lay under 70 feet of mud and debris. Over 500 people were killed and
damage estimates topped $20 million."4
The Baldwin Hills dam failed during the daylight hours, and was one of the
first disaster events documented a live helicopter broadcast. "The Baldwin
Hills Dam collapsed with the fury of a thousand cloudbursts, sending a 50-
foot wall of water down Cloverdale Avenue and slamming into homes and
cars on Dec. 14, 1963. Five people were killed. Sixty-five hillside houses
were ripped apart, and 210 homes and apartments were damaged. The flood
swept northward in a V-shaped path roughly bounded by La Brea Avenue and
Jefferson and La Cienega boulevards.
The earthen dam that created a 19-acre reservoir to supply drinking water
for West Los Angeles residents ruptured at 3:38 p.m. As a pencil-thin crack
widened to a 75-foot gash, 292 million gallons surged out. It took 77 minutes
for the lake to empty. But it took a generation for the neighborhood below to
recover. And two decades passed before the Baldwin Hills ridge top was
reborn .
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The cascade caused an unexpected ripple effect that is still being felt in Los
Angeles and beyond. It foreshadowed the end of urban-area earthen dams as
a major element of the Department of Water and Power's water storage
system. It prompted a tightening of Division of Safety of Dams control over
reservoirs throughout the state. The live telecast of the collapse from a
KTLA- TV helicopter is considered the precursor to airborne news coverage
that is now routine everywhere."5
Debris Flows
Another flood related hazard that can affect certain parts of the Southern
California region are debris flows. Most typically debris flows occur in
mountain canyons and the foothills against the San Gabriel Mountains.
However, any hilly or mountainous area with intense rainfall and the proper
geologic conditions may experience one of these very sudden and
devastating events. "Debris flows, sometimes referred to as mudslides,
mudflows, lahars, or debris avalanches, are common types of fast-moving
landslides.
These flows generally occur during periods of intense rainfall or rapid snow
melt. They usually start on steep hillsides as shallow landslides that liquefy
and accelerate to speeds that are typically about 10 miles per hour, but can
exceed 35 miles per hour. The consistency of debris flows ranges from
watery mud to thick, rocky mud that can carry large items such as boulders,
trees, and cars. Debris flows from many different sources can combine in
channels, and their destructive power may be greatly increased. They
continue flowing down hills and through channels, growing in volume with
the addition of water, sand, mud, boulders, trees, and other materials. When
the flows reach flatter ground, the debris spreads over a broad area,
sometimes accumulating in thick deposits that can wreak havoc in developed
areas."6
Coastal Flooding
Low lying coastal communities of Southern California have one other source
of flooding, coastal flooding. This occurs most often during storms which
bring higher than normal tides. Storms, the time of year and the tidal cycle
can sometimes work to bring much higher than normal tides which cause
flooding in low lying coastal areas. This hazard however is limited to those
areas.
What is the Effect of Development on Floods?
When structures or fill are placed in the floodway or floodplain water is
displaced. Development raises the river levels by forcing the river to
compensate for the flow space obstructed by the inserted structures and/or
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fill. When structures or materials are added to the floodway or floodplain and
no fill is removed to compensate, serious problems can arise. Flood waters
may be forced away from historic floodplain areas. As a result, other existing
floodplain areas may experience flood waters that rise above historic levels.
Local governments must require engineer certification to ensure that
proposed developments will not adversely affect the flood carrying capacity
of the Special Flood Hazard Area (SFHA). Displacement of only a few inches
of water can mean the
difference between no structural damage occurring in a given flood event,
and the inundation of many homes, businesses, and other facilities. Careful
attention should be given to development that occurs within the floodway to
ensure that structures are prepared to withstand base flood events.
In highly urbanized areas, increased paving can lead to an increase in
volume and velocity of runoff after a rainfall event, exacerbating the
potential flood hazards. Care should be taken in the development and
implementation of storm water management systems to ensure that these
runoff waters are dealt with effectively.
How are Flood-Prone Areas Identified?
Flood maps and Flood Insurance Studies (FIS) are often used to identify
flood-prone areas. The NFIP was established in 1968 as a means of providing
low-cost flood insurance to the nation's flood-prone communities. The NFIP
also reduces flood losses through regulations that focus on building codes
and sound floodplain management. N FIP regulations (44 Code of Federal
Regulations (CFR) Chapter 1, Section 60, 3) require that all new construction
in floodplains must be elevated at or above base flood level. There are no
flood prone zones in Santa Monica.
Flood Insurance Rate Maps (FIRM) and Flood Insurance Studies (FIS)
Floodplain maps are the basis for implementing floodplain regulations and for
delineating flood insurance purchase requirements. A Flood Insurance Rate
Map (FIRM) is the official map produced by FEMA which delineates SFHA in
communities where NFIP regulations apply. FIRMs are also used by insurance
agents and mortgage lenders to determine if flood insurance is required and
what insurance rates should apply.
Water surface elevations are combined with topographic data to develop
FIRMs. FIRMs illustrate areas that would be inundated during a 100-year
flood, floodway areas, and elevations marking the 100-year-flood level. In
some cases they also include base flood elevations (BFEs) and areas located
within the 500-year floodplain. Flood Insurance Studies and FIRMs produced
for the NFIP provide assessments of the probability of flooding at a given
location. FEMA conducted many Flood Insurance Studies in the late 1970s
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and early 1980s. These studies and maps represent flood risk at the point in
time when FEMA completed the studies. However, it is important to note that
not all 100-year or 500-year floodplains have been mapped by FEMA.
FEMA flood maps are not entirely accurate. These studies and maps
represent flood risk at the point in time when FEMA completed the studies,
and does not incorporate planning for floodplain changes in the future due to
new development. Although FEMA is considering changing that policy, it is
optional for local communities. Man-made and natural changes to the
environment have changed the dynamics of storm water
run-off si nce then.
Flood Mapping Methods and Techniques
Although many communities rely exclusively on FIRMs to characterize the
risk of flooding in their area, there are some flood-prone areas that are not
mapped but remain susceptible to flooding. These areas include locations
next to small creeks, local drainage areas, and areas susceptible to
manmade flooding.
Communities find it particularly useful to overlay flood hazard areas on tax
assessment parcel maps. This allows a community to evaluate the flood
hazard risk for a specific parcel during review of a development request.
Coordination between FEMA and local planning jurisdictions is the key to
making a strong connection with GIS technology for the purpose of flood
hazard mapping.
FEMA and the Environmental Systems Research Institute (ESRI), a private
company, have formed a partnership to provide multi-hazard maps and
information to the public via the Internet. ESRI produces GIS software,
including ArcViewC9 and ArcInfoC9 . The ESRI web site has information on
GIS technology and downloadable maps. The hazards maps provided on the
ESRI site are intended to assist communities in evaluating geographic
information about natural hazards. Flood information for most communities is
available on the ESRI web site. Visit www.esri.com for more information.
HAZARD ASSESSMENT
Hazard Identification
Hazard identification is the first phase of flood-hazard assessment.
Identification is the process of estimating: (1) the geographic extent of the
floodplain (i.e., the area at risk from flooding); (2) the intensity of the
flooding that can be expected in specific areas of the floodplain; and (3) the
probability of occurrence of flood events. This process usually results in the
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creation of a floodplain map. Floodplain maps provide detailed information
that can assist jurisdictions in making policies and land-use decisions.
Vulnerability Assessment
Vulnerability assessment is the second step of flood-hazard assessment. It
combines the floodplain boundary, generated through hazard identification,
with an inventory of the property within the floodplain. Understanding the
population and property exposed to natural hazards will assist in reducing
risk and preventing loss from future events. Because site-specific inventory
data and inundation levels given for a particular flood event (10-year, 25-
year, 50-year, 100-year, 500-year) are not readily available, calculating a
community's vulnerability to flood events is not straightforward. The amount
of property in the floodplain, as well as the type and value of structures
on those properties, should be calculated to provide a working estimate for
potential flood losses.
Risk Analysis
Risk analysis is the third and most advanced phase of a hazard assessment.
It builds upon the hazard identification and vulnerability assessment. A flood
risk analysis for the City of Santa Monica should include two components: (1)
the life and value of property that may incur losses from a flood event
(defined through the vulnerability assessment); and (2) the number and type
of flood events expected to occur over time. Within the broad components of
a risk analysis, it is possible to predict the severity of damage from a range
of events. Flow velocity models can assist in predicting the amount of
damage expected from different magnitudes of flood events. The data used
to develop these models is based on hydrological analysis of landscape
features. Changes in the landscape, often associated with human
development, can alter the flow velocity and the severity of damage that can
be expected from a flood event.
Using GIS technology and flow velocity models, it is possible to map the
damage that can be expected from flood events over time. It is also possible
to pinpoint the effects of certain flood events on individual properties. At the
time of publication of this plan, data was insufficient to conduct a risk
analysis for flood events in the City of Santa Monica. However, the current
mapping projects will result in better data that will assist in understanding
risk. This plan includes recommendations for building partnerships that will
support the development of a flood risk analysis in the City of Santa Monica.
COMMUNITY FLOOD ISSUES
What is Susceptible to Damage During a Flood Event?
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The largest impact on communities from flood events is the loss of life and
property. During certain years, property losses resulting from flood damage
are extensive. Development in the floodplains of the City of Santa Monica will
continue to be at risk from flooding because flood damage occurs on a
regular basis throughout the county. Property loss from floods strikes both
private and public property. Losses in the City of Santa Monica over the past
25 years have totaled approximately $23,102.
Property Loss Resulting from Flooding Events
The type of property damage caused by flood events depends on the depth
and velocity of the flood waters. Faster moving flood waters can wash
buildings off their foundations and sweep cars downstream. Pipelines,
bridges, and other infrastructure can be damaged when high waters combine
with flood debris. Extensive damage can be caused by basement flooding and
landslide damage related to soil saturation from flood events. Most flood
damage is caused by water saturating materials susceptible to loss (i.e.,
wood, insulation, wallboard, fabric, furnishings, floor coverings, and
appliances). In many cases, flood damage to homes renders them unlivable.
Busi ness /Ind ustry
Flood events impact businesses by damaging property and by interrupting
business. Flood events can cut off customer access to a business as well as
close a business for repairs. A quick response to the needs of businesses
affected by flood events can help a community maintain economic vitality in
the face of flood damage. Responses to business damages can include
funding to assist owners in elevating or relocating flood-prone business
structures.
Public Infrastructure
Publicly owned facilities are a key component of daily life for all citizens of
the county. Damage to public water and sewer systems, transportation
networks, flood control facilities, emergency facilities, and offices can hinder
the ability of the government to deliver services. Government can take action
to reduce risk to public infrastructure from flood events, as well as craft
public policy that reduces risk to private property from flood events.
Roads/Highways
During natural hazard events, or any type of emergency or disaster,
dependable road connections are critical for providing emergency services.
Roads systems in the City of Santa Monica are maintained by multiple
jurisdictions. Federal, state, county, and city governments all have a stake in
protecting roads from flood damage. Road networks often traverse floodplain
and floodway areas. Transportation agencies responsible for road
maintenance are typically aware of roads at risk from flooding.
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Bridges
Bridges are key points of concern during flood events because they are
important links in road networks, river crossings, and they can be
obstructions in watercourses, inhibiting the flow of water during flood events.
The bridges in the City of Santa Monica are state, county, city, or privately
owned. A state-designated inspector must inspect all state, county, and city
bridges every two years; but private bridges are not inspected, and can be
very dangerous. The inspections are rigorous, looking at everything from
seismic capability to erosion and scour.
Dam/Flood Control Channels
No dam/flood control channels exist in Santa Monica. Portions of the City
may be subject to flooding, due to flash flooding, urban flooding (storm drain
failure/infrastructure breakdown), river channel overflow, downstream
flooding, etc.) The City has not historically been vulnerable to storm surge
inundation associated with hurricanes and tropical storms.
Stone Canyon Reservoir
The Stone Canyon Reservoir is located in the City of Los Angeles. There is a
likelihood that the 10,370 acre feet capacity Stone Canyon Reservoir above
the City of Brentwood would rupture in a major earthquake, inundating
Brentwood and portions of West Los Angeles, and depositing no less than
several inches of water on the northeast portion of Santa Monica.
Riviera Reservoir
The Riviera Reservoir, 1252 Capri, Los Angeles, is owned by the City of Santa
Monica and located about two miles north of the City in Santa Monica
Canyon. The California Department of Water Resources Bulletin NO.17 lists
the reservoir as having a height of 40 feet and a storage capacity of 76 acre-
feet, which translates to approximately 25 million gallons.
The Riviera Reservoir is an off-stream, covered storage reservoir built with
vertical concrete walls. These walls are keyed top and bottom to the roof and
foundations. The north and west sidewalls on the south and east have
compacted backfill in front of them. These are the sides through which water
will pass should a failure occur.
If the failure were to occur on the east side, the structures, located at the
Riviera Golf Course, immediately below the dam will definitely be in jeopardy.
If the south side of the dam were to fail, no structures would be harmed.
However, the golf course would be flooded.
Flood waters released during the reservoir failure would empty onto the
Riviera Country Golf Course, eventually flowing into the Santa Monica Creek.
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The flood control channels will contain the flood waters directing them to the
Pacific Ocean. Santa Monica Creek located in the City of Los Angeles, is dry
the majority of the time and is not likely to be carrying flow at a time when
the reservoir might fail. Damage to any homes adjacent to the golf course is
considered unlikely. The travel time of the flood flows to the flood control
channel would be within 15 minutes.
Stormwater
Stormwater, which is more accurately called urban runoff, consists of
rainwater as well as runoff draining to city streets generated by irrigation, car
washing or the hosing down of streets and sidewalks. The majority of this
urban runoff in Santa Monica drains untreated into Santa Monica Bay via an
underground storm drain system. This system consists of 2,308 catch basins
and 64 storm drain lines which discharge at five outfalls within the city limits.
The largest of these is located on the beach at Pico Boulevard and is known
as the Pico-Kenter outfall. In addition to runoff from Santa Monica, this
outfall also discharges runoff from parts of Brentwood and West Los Angeles.
The other four outfalls are located on the beach at Montana Avenue, Wilshire
Boulevard, the Santa Monica Pier, and Ashland Avenue. The Montana and
Wilshire outfalls typically only discharge runoff to the ocean during heavy
rains. The remaining three outfalls discharge year-round, during wet and dry
periods. Under the federal Clean Water Act (CWA) the City is responsible for
the quality of the urban runoff entering the storm drain system and for the
enforcement and implementation of Local, State and Federal stormwater
regulations. City oversight of stormwater programs and operation and
maintenance of the stormwater system is coordinated by the Department of
Environmental and Public Works Management. The City is responsible for the
operation and maintenance of 824 catch basins and approximately 20 miles
of storm drain lines. The remainder of the catch basins and storm drains
within the city are owned and maintained by Los Angeles County.
The CWA and the California Ocean Plan are the primary mechanisms through
which pollutant discharges to water bodies are regulated in California. The
CWA established minimum national water quality goals and created the
National Pollutant Discharge Elimination System (NPDES) to regulate the
quality of discharged water. As of 1990 all municipal stormwater runoff
became regulated under the NPDES system. The City of Santa Monica is
currently a co-permittee with all other cities in Los Angeles County on the
County's NPDES permit which was issued in 1990. Under this permit all co-
permittees were required to develop a stormwater management plan which
includes implementation of 13 baseline best management practices (BMPs)
related to stormwater. These BMPs include: (1) catch basin labeling, (2)
institution of a public reporting program, (3) implementation of a municipal
runoff control ordinance, (4) development of public education material, (5)
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catch basin cleaning, (6) encourage increased trash receptacle usage, (7)
increased street sweeping, (8) discourage improper litter disposal, (9)
inspection of restaurants and automobile facilities, (10) encourage residents
to remove dirt, rubbish and debris from sidewalks, (11) establish a recycling
program, (12) motivate residents to properly dispose of hazardous waste,
and (13) encourage water conservation. To date Santa Monica has met all of
its compliance deadlines for implementation of these BMPs.
The Los Angeles Regional Water Quality Control Board (RWQCB) recently
completed a comprehensive revision of the NPDES permit for the Los Angeles
region. This revised permit was approved in July 1996. The permit revision
was undertaken due to a perceived need to toughen existing standards
because compliance with the existing permit had been inconsistent
throughout the region. The revised permit is more comprehensive and
specific than the previous permit and requires the City to conduct additional
employee education and institute a construction-site inspection program to
help mitigate construction-related stormwater impacts.
Wastewater
Wastewater (or "sewage") generated by Santa Monica's residential,
commercial and industrial water users flows through underground sewer lines
to the City of Los Angeles' Hyperion Treatment Plant, located approximately
7 miles southeast of Santa Monica in Playa del Rey. There the wastewater is
screened, settled, and biologically treated before being discharged into Santa
Monica Bay. Santa Monica pays a fee to Los Angeles for disposal of its
wastewater based on the monthly effluent flows to the treatment plant.
There are approximately 125 miles of sewer lines within the city limits. They
are owned by Santa Monica and are inspected and maintained by the City's
Environmental and Public Works Management Department. Permitting and
inspection of commercial and industrial wastewater generators is overseen by
the department's Industrial Waste Division. Santa Monica's sewer system is
completely separate from the stormwater system with only the wastewater
being treated before it enters the Bay.
FLOOD RESOURCE DIRECTORY
The following resource directory lists the resources and programs that can
assist county communities and organizations. The resource directory will
provide contact information for local, county, regional state and federal
programs that deal with natural hazards.
Cou nty Resou rces
Los Angeles County Public Works Department
900 S. Fremont Ave.
Alhambra, CA 91803
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Ph: 626-458-5100
Sanitation Districts of Los Angeles County
1955 Workman Mill Road
Whittier, CA 90607
Ph: 562-699-7411 x2301
State Resources
Governor's Office of Emergency Services (OES)
P.O. Box 419047
Rancho Cordova, CA 95741-9047
Ph: 916 845- 8911
Fx: 916 845- 8910
California Resources Agency
1416 Ninth Street, Suite 1311
Sacramento, CA 95814
Ph: 916-653-5656
California Department of Water Resources (DWR)
1416 9th Street
Sacramento, CA 95814
Ph: 916-653-6192
California Department of Conservation: Southern California Regional Office
655 S. Hope Street, #700
Los Angeles, CA 90017-2321
Ph: 213-239-0878
Fx: 213-239-0984
Federal Resources and Programs
Federal Emergency Management Agency (FEMA)
FEMA provides maps of flood hazard areas, various publications related
to flood mitigation, funding for flood mitigation projects, and technical
assistance, FEMA also operates the National Flood Insurance Program.
FEMA' s mission is to reduce loss of life and property and protect the
nation's critical infrastructure from all types of hazards through a
comprehensive, risk-based, emergency management program of
mitigation, preparedness, response and recovery.
Federal Emergency Management Agency, Region IX
1111 Broadway, Suite 1200
Oakland, CA 94607
Ph: 510-627-7100
Fx: 510-627-7112
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Federal Emergency Management Agency, Mitigation Division
500 C Street, S. W.
Washington, D.C. 20472
Ph: 202-566-1600
FEMA' s List of Flood Related Websites
This site contains a long list of flood related Internet sites from
"American Heritage Rivers" to "The Weather Channel" and is a good
starting point for flood information on the Internet.
Contact: Federal Emergency Management Agency, Phone: (800) 480-2520
Website: http://www.fema.gov/nfip/related.htm
National Floodplain Insurance Program (NFIP)
500 C Street, S. W.
Washington, D.C. 20472
Ph: 202-566-1600
The Floodplain Management Association
The Floodplain Management website was established by the Floodplain
Management Association (FMA) to serve the entire floodplain
management community. It includes full-text articles, a calendar of
upcoming events, a list of positions available, an index of publications
available free or at nominal cost, a list of associations, a list of firms
and consultants in floodplain management, an index of newsletters
dealing with flood issues (with hypertext links if available), a section
on the basics of floodplain management, a list of frequently asked
questions (FAQs) about the Website, and a catalog of Web links.
Floodplain Management Association
P.O. Box 50891
Sparks, NV 89435-0891
Ph: 775-626-6389
Fx: 775-626-6389
The Association of State Floodplain Managers
The Association of State Floodplain Managers is an organization of
professionals involved in floodplain management, flood hazard
mitigation, the National Flood Insurance Program, and flood
preparedness, warning, and recovery. ASFPM fosters communication
among those responsible for flood hazard activities, provides technical
advice to governments and other entities about proposed actions or
policies that will affect flood hazards, and encourages flood hazard
research, education, and training. The ASFPM Web site includes
information on how to become a member, the organization's
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constitution and bylaws, directories of officers and committees, a
publications list, information on upcoming conferences, a history of the
association, and other useful information and
Contact: The Association of State Floodplain Managers
Address: 2809 Fish Hatchery Road, Madison, WI 53713 Phone: (608) 274-
0123
Website: http://www.floods.org
National Weather Service
The National Weather Service provides flood watches, warnings, and
informational statements in the City of Santa Monica.
National Weather Service
520 North Elevar Street
Oxnard, CA 93030
Ph: 805-988- 6615
Office of Hydrology, National Weather Service
The National Weather Service s Office of Hydrology (OH) and its
Hydrological Information Center offer information on floods and other
aquatic disasters, This site offers current and historical data including
an archive of past flood summaries, information on current hydrologic
conditions, water supply outlooks, an Automated Local Flood Warning
Systems Handbook, Natural Disaster Survey Reports, and other
scientific publications on hydrology and flooding.
National Weather Service, Office of Hydrologic Development
1325 East West Highway, SSMC2
Silver Spring, MD 20910
Ph: 301-713-1658
Fx: 301-713-0963
Resources Conservation Service (N RCS), US Department of Agriculture
NRCS provides a suite of federal programs designed to assist state and
local governments and landowners in mitigating the impacts of flood
events. The Watershed Surveys and Planning Program and the Small
Watershed Program provide technical and financial assistance to help
participants solve natural resource and related economic problems on
a watershed basis. The Wetlands Reserve Program and the Flood Risk
Reduction Program provide financial incentives to landowners to put
aside land that is either a wetland resource, or that experiences
frequent flooding. The Emergency Watershed Protection Program
(EWP) provides technical and financial assistance to clear debris from
clogged waterways, restore vegetation, and stabilizing riverbanks. The
measures taken under EWP must be environmentally and economically
sound and generally benefit more that one property.
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National Resources Conservation Service
14th and Independence Ave., SW, Room 5105-A
Washington, DC 20250
Ph: 202-720-7246
Fx: 202-720-7690
USGS Water Resources
This web page offers current US water news; extensive current
(including real-time) and historical water data; numerous fact sheets
and other publications; various technical resources; descriptions of
ongoing water survey programs; local water information; and
connections to other sources of water information.
USGS Water Resources
6000 J Street Placer Hall
Sacramento, CA 95819-6129
Ph: 916-278-3000
Fx: 916-278-3070
Bureau of Reclamation
The mission of the Bureau of Reclamation is to manage, develop, and
protect water and related resources in an environmentally and
economically sound manner in the interest of the American public. The
Bureau provides leadership and technical expertise in water resources
development and in the efficient use of water through initiatives
including conservation, reuse, and research. It protects the public and
the environment through the adequate maintenance and appropriate
operation of Reclamation's facilities and manages Reclamation's
facilities to fulfill water user contracts and protect and/or enhance
conditions for fish, wildlife, land, and cultural resources.
Mid Pacific Regional Office
Federal Office Building
2800 Cottage Way
Sacramento CA 95825-1898
Ph: 916- 978-5000
Fax 916- 978-5599
http://www.usbr.gov/
Army Corps of Engineers
The Corps of Engineers administers a permit program to ensure that
the nation's waterways are used in the public interest. Any person,
firm, or agency planning to work in waters of the United States must
first obtain a permit from the Army Corps of Engineers. The Corps is
responsible for the protection and development of the nation's water
resources, including navigation, flood control, energy production
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through hydropower management, water supply storage and
recreation.
US Army Corps of Engineers
P.O. Box 532711
Los Angeles CA 90053- 2325
Ph: 213-452- 3921
American Public Works Association
2345 Grand Boulevard, Suite 500
Kansas City, MO 64108-2641
Ph: 816-472-6100
Fx: 816-472-1610
Publications
NFIP Community Rating System Coordinator's Manual
Indianapolis, IN.
This informative brochure explains how the Community Rating System
works and what the benefits are to communities. It explains in detail
the CRS point system, and what activities communities can pursue to
earn points. These points then add up to the "rating" for the
community, and flood insurance premium discounts are calculated
based upon that "rating" The brochure also provides a table on the
percent discount realized for each rating (1-10). Instructions on how
to apply to be a CRS community are also included.
Contact: NFIP Community Rating System
Phone: (800) 480-2520 or (317) 848-2898
Website: http://www.fema.gov/nfip/crs
Floodplain Management: A Local Floodplain Administrator's Guide to the NFIP
This document discusses floodplain processes and terminology. It
contains floodplain
management and mitigation strategies, as well as information on the
NFIP, CRS, Community Assistance Visits, and floodplain development
standards.
Contact: National Flood Insurance Program Phone: (800) 480-2520
Website: http://www.fema,gov/nfip/
Flood Hazard Mitigation Planning: A Community Guide, (June 1997).
Massachusetts Department of Environmental Management.
This informative gUide offers a 10-step process for successful flood
hazard mitigation. Steps include: map hazards, determine potential
damage areas, take an inventory of facilities in the flood zone,
determine what is or is not being done about flooding, identify gaps in
protection, brainstorm alternatives and actions, determine feasible
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actions, coordinate with others, prioritize actions, develop strategies
for implementation, and adopt and monitor the plan.
Contact: Massachusetts Flood Hazard Management Program Phone: (617)
626-1250
Website: http://www.magnetstate.ma.us/dem/programs/mitigate
Reducing Losses in High Risk Flood Hazard Areas: A Guidebook for Local
Officials, (February 1987), FEMA-116.
This gUidebook offers a table on actions that communities can take to
reduce flood losses. It also offers a table with sources for floodplain
mapping assistance for the various types of flooding hazards, There is
information on various types of flood hazards with regard to existing
mitigation efforts and options for action (policy and programs,
mapping, regulatory, nonregulatory). Types of flooding which are
covered include alluvial fan, areas behind levees, areas below unsafe
dams, coastal flooding, flash floods, fluctuating lake level floods,
ground failure triggered by earthquakes, ice jam flooding, and
mudslides.
Contact: Federal Emergency Management Agency Phone: (800) 480-2520
Website: http://www.fema.gov
Flood Endnotes
1. http://www.lalc.k12.ca.us/target/units/river/tour/hist.html
2. Gumprecht, Blake, 1999, Johns Hopkins University Press, Baltimore, MD.
3. Ibid
4. http://www.usc.edu/isd/archives/la/scandals/st_francis_dam.html
5. http://www.latimes.com/news/local/surroundings/la-
mesurround lldecll,O, 1754871.story?coll =Ia-adelphia-right-rail
6. http://www.fema.gov/rrr/talkdiz/landslide.shtm#
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2.4 Tsunami
Table of Contents
Why Are Tsunamis a Threat to Southern California? .............................. 121
What Are Tsunamis?........................................................................ 121
What Causes Tsunamis?................................................................... 121
Tsunami Characteristics.................................................................... 123
History of Regional Tsunamis .............................................................125
Tsunami Hazard Identification............................................................ 126
Tsunami Watches and Warnings .........................................................128
Community Tsunami Issues............................................................... 130
Existing Tsunami Mitigation Activities .................................................. 131
Tsu na m i Resou rce Di rectory .............................................................. 131
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Why Are Tsunamis a Threat to Southern California?
History has shown that the probability of a tsunami in the City of Santa
Monica is an extremely low threat. However, if a tsunami should occur, the
consequences would be great. As shown on the tsunami run-up map (Map
2.6 on page 122), the entire City of Santa Monica coastline could be
impacted. Thirty percent of the City's residents would have to be evacuated.
The impact could cause loss of life, destroy thousands of high priced homes
and greatly affect the City's downtown and coastal businesses, and impact
tourism. Even if all residents and visitors were safely evacuated, the damage
to property in this densely populated, high property value area would still be
tremendous.
California's Tsunamis
"Since 1812, the California coast has had 14 tsunamis with wave heights
higher than three feet; six of these were destructive. The Channel Islands
were hit by a big tsunami in the early 1800s. The worst tsunami resulted
from the 1964 Alaskan earthquake and caused 12 deaths and at least $17
million in damages in northern California."xli
What are Tsunamis?
The phenomenon we call "tsunami" (soo-NAH-mee) is a series of traveling
ocean waves of extremely long length generated primarily by earthquakes
occurring below or near the ocean floor. Underwater volcanic eruptions and
landslides can also generate tsunamis. In the deep ocean, the tsunami
waves move across the deep ocean with a speed exceeding 500 miles per
hour, and a wave height of only a few inches. Tsunami waves are
distinguished from ordinary ocean waves by their great length between wave
crests, often exceeding 60 miles or more in the deep ocean, and by the time
between these crests, ranging from 10 minutes to an hour.
As they reach the shallow waters of the coast, the waves slow down and the
water can pile up into a wall of destruction up to 30 feet or more in height.
The effect can be amplified where a bay, harbor or lagoon funnels the wave
as it moves inland. Large tsunamis have been known to rise over 100 feet.
Even a tsunami 1-3 feet high can be very destructive and cause many deaths
and injuries.
What causes Tsunami?
There are many causes of tsunamis but the most prevalent is earthquakes.
In addition, landslides, volcanic eruptions, explosions, and even the impact of
cosmic bodies, such as meteorites, can generate tsunamis.
Plate Tectonics
Plate Tectonic theory is based on an earth model characterized by a small
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number of lithospheric plates, 40 to 150 miles thick, that float on a viscous
under-layer called the asthenosphere. These plates, which cover the entire
surface of the earth and contain both the continents and sea floor, move
relative to each other at rates of up to several inches per year. The region
where two plates come in contact is called a plate boundary, and the way in
which one plate moves relative to another determines the type of boundary:
spreading, where the two plates move away from each other; subduction,
where the two plates move toward each other and one slides beneath the
other; and transform, where the two plates slide horizontally past each
other. Subduction zones are characterized by deep ocean trenches, and the
volcanic islands or volcanic mountain chains associated with the many
subduction zones around the Pacific rim are sometimes called the Ring of
Fire.
Earthquakes and Tsunamis
An earthquake can be caused by volcanic activity, but most are generated by
movements along fault zones associated with the plate boundaries. Most
strong earthquakes, representing 80% of the total energy released worldwide
by earthquakes, occur in subduction zones where an oceanic plate slides
under a continental plate or another younger oceanic plate.
Not all earthquakes generate tsunamis. To generate a tsunami, the fault
where the earthquake occurs must be underneath or near the ocean, and
cause vertical movement of the sea floor over a large area, hundreds or
thousands of square miles. "By far, the most destructive tsunamis are
generated from large, shallow earthquakes with an epicenter or fault line
near or on the ocean floor."xlii The amount of vertical and horizontal motion
of the sea floor, the area over which it occurs, the simultaneous occurrence
of slumping of underwater sediments due to the shaking, and the efficiency
with which energy is transferred from the earth's crust to the ocean water
are all part of the tsunami generation mechanism. The sudden vertical
displacements over such large areas, disturb the ocean's surface, displace
water, and generate destructive tsunami waves.xliii
Although all oceanic regions of the world can experience tsunamis, the most
destructive and repeated occurrences of tsunamis are in the Pacific Rim
region.
Tsunami Earthquakes
The September 2, 1992 earthquake (magnitude 7.2) was barely felt by
residents along the coast of Nicaragua. Located well off-shore, the severity
of shaking on a scale of I to XII, was mostly II along the coast, and reached
III at only a few places. Twenty to 70 minutes after the earthquake
occurred, a tsunami struck the coast of Nicaragua with wave amplitudes up
to 13 feet above normal sea level in most places and a maximum run-up
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height of 35 ft. The waves caught coastal residents by complete surprise and
caused many casualties and considerable property damage.
This tsunami was caused by a tsunami earthquake, an earthquake that
produces an unusually large tsunami relative to the earthquake magnitude.
Tsunami earthquakes are characterized by a very shallow focus, fault
dislocations greater than several meters, and fault surfaces that are smaller
than for a normal earthquake.
Tsunami earthquakes are also slow earthquakes, with slippage along the
fault beneath the sea floor occurring more slowly than it would in a normal
earthquake. The only known method to quickly recognize a tsunami
earthquake is to estimate a parameter called the seismic moment using very
long period seismic waves (more than 50 seconds/cycle). Two other
destructive and deadly tsunamis from tsunami earthquakes have occurred in
recent years in Java, Indonesia (June 2, 1994) and Peru (February 21,
1996).
"Less frequently, tsunami waves can be generated from
displacements of water resulting from rock falls, icefalls and
sudden submarine landslides or slumps. Such events may be
caused impulsively from the instability and sudden failure of
submarine slopes, which are sometimes triggered by the ground
motions of a strong earthquake. For example in the 1980's,
earth moving and construction work of an airport runway along
the coast of Southern France, triggered an underwater landslide,
which generated destructive tsunami waves in the harbor of
Thebes. "xliv
TSUNAMI CHARACTERISTICS
How Fast?
Unnoticed tsunami waves can travel at the speed of a commercial jet plane,
over 500 miles per hour. They can move from one side of the Pacific Ocean
to the other in less than a day. This great speed makes it important to be
aware of the tsunami as soon as it is generated. Scientists can predict when
a tsunami will arrive at various places by knowing the source characteristics
of the earthquake that generated the tsunami and the characteristics of the
sea floor along the paths to those places. Tsunamis travel much slower in
more shallow coastal waters where their wave heights begin to increase
dramatically.
How Big?
Offshore and coastal features can determine the size and impact of tsunami
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waves. Reefs, bays, entrances to rivers, undersea features and the slope of
the beach all help to modify the tsunami as it attacks the coastline. When
the tsunami reaches the coast and moves inland, the water level can rise
many feet. In extreme cases, water level has risen to more than 50 feet for
tsunamis of distant origin and over 100 feet for tsunami waves generated
near the earthquake's epicenter. The first wave may not be the largest in
the series of waves. One coastal community may see no damaging wave
activity while in another nearby community destructive waves can be large
and violent. The flooding can extend inland by 1000 feet or more, covering
large expanses of land with water and debris.
How Frequent?
Since scientists cannot predict when earthquakes will occur, they cannot
determine exactly when a tsunami will be generated. However, by looking at
past historical tsunamis and run-up maps, scientists know where tsunamis
are most likely to be generated. Past tsunami height measurements are
useful in predicting future tsunami impact and flooding limits at specific
coastal locations and communities.
TYPES OF TSUNAMIS
Pacific-wide and Regional Tsunamis
Tsunamis can be categorized as "local" and Pacific-wide. Typically, a Pacific-
wide tsunami is generated by major vertical ocean bottom movement in
offshore deep trenches. A "local" tsunami can be a component of the Pacific-
wide tsunami in the area of the earthquake or a wave that is confined to the
area of generation within a bay or harbor and caused by movement of the
bay itself or landslides.
The last large tsunami that caused widespread death and destruction
throughout the Pacific was generated by an earthquake located off the coast
of Chile in 1960. It caused loss of life and property damage not only along
the Chile coast but also in Hawaii and as far away as Japan. The Great
Alaskan Earthquake of 1964 killed 106 people and produced deadly tsunami
waves in Alaska, Oregon and California.
In July 1993, a tsunami generated in the Sea of Japan killed over 120 people
in Japan. Damage also occurred in Korea and Russia but spared other
countries since the tsunami wave energy was confined within the Sea of
Japan. The 1993 Japan Sea tsunami is known as a "regional event" since its
impact was confined to a relatively small area. For people living along the
northwestern coast of Japan, the tsunami waves followed the earthquake
within a few minutes.
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During the 1990's, destructive regional tsunamis also occurred in Nicaragua,
Indonesia, the Philippines, Papua New Guinea, and Peru, killing thousands of
people. Others caused property damage in Chile and Mexico. Some damage
also occurred in the far field in the Marquesas Islands (French Polynesia)
from the July 30, 1995, Chilean and February 21, 1996, Peruvian tsunamis.
In less than a day, tsunamis can travel from one side of the Pacific to the
other. However, people living near areas where large earthquakes occur
may find that the tsunami waves will reach their shores within minutes of the
earthquake. For these reasons, the tsunami threat to many areas such as
Alaska, the Philippines, Japan and the United States West Coast can be
immediate (for tsunamis from nearby earthquakes which take only a few
minutes to reach coastal areas) or less urgent (for tsunamis from distant
earthquakes which take from three to 22 hours to reach coastal areas).
HISTORY OF REGIONAL TSUNAMIS
Local
The local tsunami may be the most serious threat as it strikes suddenly,
sometimes before the earthquake shaking stops. Alaska has had six serious
local tsunamis in the last 80 years and Japan has had many more.
Local History of Tsunamis
Tsunamis have been reported since ancient times. They have been
documented extensively in California since 1806. Although the majority of
tsunamis have occurred in Northern California, Southern California has been
impacted as well. In the 1930's, four tsunamis struck the LA, Orange
County, and San Diego coastal areas. In Orange County the tsunami wave
reached heights of 20 feet or more above sea level. In 1964, following the
Alaska 8.2 earthquake, tidal surges of approximately 4 feet to 5 feet hit the
Huntington Harbour area causing moderate damage.
Table 2.5 Tsunami Events In California 1930-2004
Date Location Maximum Run Earthquake
up*(m) Magnitude
08/31/1930 Redondo Beach 6.10 5.2
08/31/1930 Santa Monica 6.10 5.2
08/31/1930 Venice
6.10
5.2
03/11/1933 La Jolla 0.10 6.3
03/11/1933 Long Beach 0.10 6.3
08/21/1934 I Newport Beach I
12.00
Unknown
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02/09/1941 San Diego Unknown 6.6
10/18/1989 Monterey 0.40 7.1
10/18/1989 Moss Landing 1.00 7.1
10/18/1989 Santa Cruz 0.10 7.1
04/25/1992 Arena Cove 0.10 7.1
04/25/1992 Monterey 0.10 7.1
09/01/1994 Crescent City 0.14 7.1
11/04/2000 Point Arguello 5.00
Source: Worldwide Tsunami Database www.ngdc.noaa.gov
* Maximum Run up (M)-The maximum water height above sea level in
meters. The run-up is the height the tsunami reached above a reference
level such as mean sea level. It is not always clear which reference level was
used.
TSUNAMI HAZARD ASSESSMENT
Hazard Identification
A tsunami threat to the City of Santa Monica is considered low to moderate.
Santa Monica occupies a central position along the arching shoreline of Santa
Monica Bay. The beach, which has grown through accretion, is several
hundred feet wide-one of the widest stretches of beach in this part of
southern California.
Santa Monica sits atop a coastal plain that is defined on its northern
boundary by Santa Monica Canyon. This deep arroyo attracted native
American settlements and then the area's first European settlement in the
1860s-a summer colony for residents of the new City of Los Angeles some
twelve miles inland along the foot of the mountains. South of the canyon, the
rugged terrain gives way to the gently south sloping upland of the City's
north side. The land descends to a historic drainage channel that ran west to
the sea along the general line of the present-day Santa Monica freeway. This
drainage formed a distinctive draw that originally marked the edge of the
Palisades and defined the City's southerly border. It is this collision of this
south sloping upland with the southwesterly trending coastline that creates
the City's most memorable topographic feature-the Palisades-a sheer cliff
of fragile sandstone that rises about 100 feet above the coast that separates
the northern portion of the City from the beach below.
Damage factors of tsunamis
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Tsunamis cause damage in three ways: inundation, wave impact on
structures, and erosion.
"Strong, tsunami-induced currents lead to the erosion of
foundations and the collapse of bridges and sea walls. Flotation
and drag forces move houses and overturn railroad cars.
Considerable damage is caused by the resultant floating debris,
including boats and cars that become dangerous projectiles that
may crash into buildings, break power lines, and may start fires.
Fires from damaged ships in ports or from ruptured coastal oil
storage tanks and refinery facilities, can cause damage greater
than that inflicted directly by the tsunami. Of increasing concern
is the potential effect of tsunami draw down, when receding
waters uncover cooling water intakes of nuclear power plants."xlv
A United States Government study reports that, "Local earthquakes will not
generate a tsunami, in this area". Tsunamis are due to large off-shore
earthquakes and ocean landslides. Dangerous tsunamis would most likely
originate in the Aleutian and Chilean offshore submarine trenches. The City
of Santa Monica has western facing beaches that are vulnerable to tsunamis
or tidal surges from the from the west.
Predicted wave heights, exclusive of tide and storm generated wave heights
are:
For a 100 year occurrence
4.0 feet minimum
For a 500 year occurrence
6.8 feet minimum
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6.6 feet average
9.2 feet maximum
11.4 feet average
16.0 feet maximum
According to the Modern Tsunami Run-up Map (see next page) the entire
coastline of Santa Monica would be severely impacted. During the summer
months City of Santa Monica can attract over 200,000 people a day to its
beaches. If a tsunami were to occur it could devastate the entire coastal
area.
Tsunami Run Up In Santa Monica
Los Angeles
Tsunami Hazard:
Maximum Runup
!::] 1Jl.i;:<;'~i!J;n.~~<i;:!IWI;\mjFI.l:il~p
_.""""..~,~.....,....~",,:'I!'''' '''''=''-' ,,'" '='~ """ ,....,"'
''''''''''~D'
TSUNAMI WATCHES AND WARNINGS
Warning System
The tsunami warning system in the United States is a function of the National
Oceanic and Atmospheric Administration's (NOAA) National Weather Service.
Development of the tsunami warning system was impelled by the disastrous
waves generated in Alaska in April 1946, which surprised Hawaii and the U.S.
West Coast, taking a heavy toll in life and property.
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The disastrous 1964 tsunami resulted in the development of a regional
warning system in Alaska. The Alaska Tsunami Warning Center is in Palmer,
Alaska. This facility is the nerve center for an elaborate telemetry network of
remote seismic stations in Alaska, Washington, California, Colorado, and
other locations. Tidal data is also telemetered directly to the ATWC from
eight Alaskan locations. Tidal data from Canada, Washington, Oregon, and
California are available via telephone, teletype, and computer readout.
Watch vs. Warning
The National Warning System (NAWAS) is an integral part of the Alaska
Tsunami Warning Center. Reports of major earthquakes occurring anywhere
in the Pacific Basin that may generate seismic sea waves are transmitted to
the Honolulu Observatory for evaluation. An Alaska Tsunami Warning Center
is also in place for public notification of earthquakes in the Pacific Basin near
Alaska, Canada, and Northern California. The Observatory Staff determines
action to be taken and relays warnings over the NAWAS circuits to inform
and warn West Coast states. The State NAWAS circuit is used to relay the
information to the Orange County Operational Area warning center which will
in turn relay the information to local warning points in coastal areas. The
same information is also transmitted to local jurisdictions over appropriate
radio systems, teletype, and telephone circuits to ensure maximum
dissemination.
A Tsunami Watch Bulletin is issued if an earthquake has occurred in the
Pacific Basin and could cause a tsunami. A Tsunami Warninq Bulletin is
issued when an earthquake has occurred and a tsunami is spreading across
the Pacific Ocean. When a threat no longer exists, a Cancellation Bulletin is
issued.
When there is a high probability that a tsunami will reach City of Santa
Monica, the City will activate its Warning
Siren System. When activated, the
sirens alert the public to turn on their
AM/FM radio and listen to the Emergency
Alerting System (EAS). The City Public
Information Officer will activate EAS and
provide them with a prepared statement
of who should evacuate, where to
evacuate to and what routes to take.
Evacuation
Upon receipt of a Tsunami
Watch/Warning Bulletin, an immediate
evaluation will be made of the potential
129
threat to the coastal areas of the City of Santa Monica. After a thorough
evaluation, a determination will be made as to the degree of evacuation
necessary to eliminate any threats to the resident and visiting populations.
Once the degree of evacuation has been determined, the Police Department
will begin an immediate evacuation of the low-lying areas that have been
determined to be at risk. Officers will block all movements on Pacific Coast
Highway except those necessary to gain access to the nearest arterial
highway leading away from the ocean. The population will be directed inland
using the closest available northbound or eastbound arterial highway. It is
imperative that the evacuation routes be kept open and clear at all times.
Neighboring jurisdictions along with the American Red Cross would be called
upon for care and shelter duties. Displacing residents, utilization of Cities
resources, and disaster cleanup can cause an economic hardship on all
impacted communities.
Vulnerability and Risk
With an analysis of tsunami events depicted in the "Local History" section, we
can deduce the common tsunami impact areas will include impacts on life,
property, infrastructure and transportation.
COMMUNITY TSUNAMI ISSUES
What is Susceptible to Tsunami?
Life and Property
The largest impact on the community from a tsunami event is the loss of life
and property. Known risk areas include, but are not limited to:
Beaches
Santa Monica Pier
All buildings and apartments on west of Pacific Coast Highway (PCH)
Vehicles and pedestrians on PCH in low lying areas
Using the Tsunami Warning and Watch Bulletin would provide time to allow
coastal residents to evacuate and seek higher ground for shelter. This would
greatly reduce injuries and loss of life.
Commercial
City of Santa Monica's pier and beaches are world famous. During summer
months up to 200,000 people a day come into the community to stay in the
beautiful hotels and shop at the unique boutiques. The local government
relies heavily on tourism and sales tax. A tsunami event would impact
businesses by damaging property and by interrupting business and services.
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Any residential or commercial structure with weak reinforcement would be
susceptible to damage.
Infrastructure
Tsunamis (and earthquakes) can damage buildings, power lines, and other
property and infrastructure due to flooding. Tsunamis can result in collapsed
or damaged buildings or blocked roads and bridges, damaged traffic signals,
streetlights, and parks, among others. Damage to public water and sewer
systems, transportation networks, and flood channels would greatly impact
daily life for residents.
Roads blocked by objects during a tsunami may have severe consequences
to people who are attempting to evacuate or who need emergency services.
Emergency response operations can be complicated when roads are blocked
or when power supplies are interrupted. Industry and commerce can suffer
losses from interruptions in electric services and from extended road
closures. They can also sustain direct losses to buildings, personnel, and
other vital equipment. There are direct consequences to the local economy
resulting from tsunamis related to both physical damages and interrupted
services.
Existing Mitigation Activities
City of Santa Monica has implemented a number of tsunami mitigation
activities over the years. Some of the current mitigation programs include:
. The City's Warning Siren System
. Public Information Plan for Emergency Alerting System (EAS)
· Disaster Preparedness Public Education
TSUNAMI RESOURCE DIRECTORY
Cou nty Resou rces
Los Angeles County Office of Emergency Management
Jeff Terry, Tsunami Coordinator
1375 N. Eastern Ave.
Los Angeles, CA., 90063
Telephone: 323-980- 2260
www.lacoeoc.orq
Federal Resources and Programs
West Coast & Alaska Tsunami Warning Center
The West Coast/Alaska Tsunami Warning Center's objectives are to
rapidly locate and size major earthquakes in the Pacific basin,
determine their tsunami potential, predict tsunami arrival times and,
when possible, runup on the coast, and provide timely and effective
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tsunami information and warning bulletins for the Pacific coastal
populations of California, Oregon, Washington, British Columbia, and
Alaska.
910 S. Felton St.
Palmer, AK 99645
Ph: 907-745-4212
Fx: 907-745-6071
Additional Resources
University of Southern California
Department of Civil and Environmental Engineering
Tsunami Research Group
Dr. Costas E. Synolakis, Director
3620 S. Vermont Avenue
Kaprielian Hall 210
Los Angeles, CA 90089-2531
Ph: 213-740-0603
Fx: 213-744-1426
civileng@usc.edu
Tsunami Endnotes
1. htto:/ /education .sdsc.edu/ootiouter/htmILinks/california tsunami. html
2. htto:/ /www.orh.noaa.qov/itic/librarv/abouttsu/faqs.html# 1
3. Ibid
4. Ibid
5. Ibid
132 DRAFT Santa Monica Hazard Mitigation Plan
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2.5 Wildfires
Table of Contents
Why Are Wi Idfi res a Th reat to City of Santa Mon ica __________________________________________134
History of Wi I dfi res . __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ ___ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ ___ __ __ __134
Wildfire Characteristics
136
Wildfire Hazard Identification
140
v u I n e ra b i I ity and Ri s k___ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ ___ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ ___ __ __ __141
Com m unity Wi I dfi re Issues ______________________________________________________________________________________141
Wi Idfi re Resou rce Directory _____________________________________________________________________________________147
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Why are Wildfires a Threat to Southern California?
For thousands of years, fires have been a natural part of the ecosystem in
Southern California. However, wildfires present a substantial hazard to life
and property in communities built within or adjacent to hillsides and
mountainous areas. There is a huge potential for losses due to
wildland/urban interface fires in Southern California. According to the
California Division of Forestry (CDF), there were over seven thousand
reportable fires in California in 2003, with over one million acres burned.xlvi
According to CDF statistics, in the October, 2003 Firestorms, over 4,800
homes were destroyed and 22 lives were lost. xlvii
The 2003 Southern California Fires
The fall of 2003 marked the most destructive wildfire season in California
history. In a ten day period, 12 separate fires raged across Southern
California in Los Angeles, Riverside, San Bernardino, San Diego and Ventura
counties. The massive "Cedar" fire in San Diego County alone consumed of
2,800 homes and burned over a quarter of a million acres.
Table 2.6 October 2003 Firestorm Statistics
County Fire Date Acres Homes Homes Lives
Name Began Burned Lost Damaged Lost
Riverside Pass 10/21/03 2,397 3 7 0
Los Angeles Padua 10/21/03 10,446 59 0 0
San Grand 10/21/03 69,894 136 71 0
Bernardino Prix
San Diego Roblar 2 10/21/03 8,592 0 0 0
Ventura Piru 10/23/03 63,991 8 0 0
Los Angeles Verdale 10/24/03 8,650 1 0 0
Ventura Simi 10/25/03 108,204 300 11 0
San Diego Cedar 10/25/03 273,246 2,820 63 14
San Old 10/25/03 91,281 1,003 7 6
Bernardino
San Diego Otay / 10/26/03 46,000 6 11 0
Mine
Riverside Mountain 10/26/03 10,000 61 0 0
San Diego Paradise 10/26/03 56,700 415 15 2
Total Losses 749,401 4,812 185 22
Source: http://www.fire.ca .gov/php/fire_er _content/downloads/2003LargeFires. pdf
Historic Fires in Southern California
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Large fires have been part of the Southern California landscape for
millennia. "Written documents reveal that during the 19th century
human settlement of southern California altered the fire regime of
coastal California by increasing the fire frequency. This was an era of
very limited fire suppression, and yet like today, large crown fires
covering tens of thousands of acres were not uncommon. One of the
largest fires in Los Angeles County (60,000 acres) occurred in 1878,
and the largest fire in Orange County's history, in 1889, was over half
a million acres."xlviii
Table 2.7 Large Historic Fires in California 1961-2003
20 Largest California Wildland Fires (Structures Destroyed)
(Southern California fires are shown in bold)
Fire Name Date County Acres Structures Deaths
1 Tunnel October 1991 Alameda 1,600 2,900 25
2 Cedar October 2003 San Diego 273,246 2,820 14
3 Old October 2003 San 91,281 1,003 6
Bernardino
4 Jones October 1999 Shasta 26,200 954 1
5 Paint June 1990 Santa Barbara 4,900 641 1
6 Fountain August 1992 Shasta 63,960 636 0
7 City of Berkeley September Alameda 130 584 0
1923
8 Bel Air November Los Angeles 6,090 484 0
1961
9 Laguna Fire October 1993 Orange 14,437 441 0
10 Paradise October 2003 San Diego 56,700 415 2
11 Laguna September San Diego 175,425 382 5
1970
12 Panorama November San 23,600 325 4
1980 Bernardino
13 Topanga November Los Angeles 18,000 323 3
1993
14 4ger Septem ber Nevada 33,700 312 0
1988
15 Simi October 2003 Ventura 108,204 300 0
16 Sycamore July 1977 Sa nta 805 234 0
Barbara
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17 Canyon Septem ber Shasta 2,580 230 0
1999
18 Kannan October 1978 Los Angeles 25,385 224 0
19 Kinneloa October 1993 Los Angeles 5,485 196 1
19 Grand Prix October 2003 San 59,448 196 0
Bernardino
20 Old Gulch August 1992 Calaveras 17,386 170 0
http://www.fire.ca .gov/FireEmergencyResponse/HistoricaIStatistics/PDF/20LSTRUCTU RES. pdf
"Structures" is meant to include all loss - homes and outbuildings, etc.
During the 2002 fire season, more than 6.9 million acres of public and
private lands burned in the US, resulting in loss of property, damage to
resources and disruption of community services.xlix Taxpayers spent more
than $1.6 billionl to combat more than 88,400 fires nationwide. Many of
these fires burned in wildland/urban interface areas and exceeded the fire
suppression capabilities of those areas. Table 8-3 illustrates fire suppression
costs for state, private and federal lands.
Wildfire Characteristics
There are three categories of interface fire:li The classic wildland/urban
interface exists where well-defined urban and suburban development presses
up against open expanses of wildland areas; the mixed wildland/urban
interface is characterized by isolated homes, subdivisions and small
communities situated predominantly in wildland settings; and the occluded
wildland/urban interface exists where islands of wildland vegetation occur
inside a largely urbanized area. Certain conditions must be present for
significant interface fires to occur. The most common conditions include:
hot, dry and windy weather; the inability of fire protection forces to contain
or suppress the fire; the occurrence of multiple fires that overwhelm
committed resources; and a large fuel load (dense vegetation). Once a fire
has started, several conditions influence its behavior, including fuel
topography, weather, drought and development.
Southern California has two distinct areas of risk for wildland fire. The
foothills and lower mountain areas are most often covered with scrub brush
or chaparral. The higher elevations of mountains also have heavily forested
terrain. The lower elevations covered with chaparral create one type of
exposure.
""Past fire suppression is not to blame for causing large
shrubland wildfires, nor has it proven effective in halting them.''''
said Dr. Jon Keeley, a USGS fire researcher who studies both
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southern California shrublands and Sierra Nevada forests.
''''Under Santa Ana conditions, fires carry through all chaparral
regardless of age class. Therefore, prescribed burning programs
over large areas to remove old stands and maintain young
growth as bands of firebreaks resistant to ignition are futile at
stoppi ng these wi Idfi res. ,,,,Iii
The higher elevations of Southern California's mountains are typically heavily
forested. The magnitude of the 2003 fires is the result of three primary
factors: (1) severe drought, accompanied by a series of storms that produce
thousands of lightning strikes and windy conditions; (2) an infestation of bark
beetles that has killed thousands of mature trees; and (3) the effects of
wildfire suppression over the past century that has led to bUildup of brush
and small diameter trees in the forests.
"When Lewis and Clark explored the Northwest, the forests were
relatively open, with 20 to 25 mature trees per acre.
Periodically, lightning would start fires that would clear out
underbrush and small trees, renewing the forests. Today's
forests are completely different, with as many as 400 trees
crowded onto each acre, along with thick undergrowth. This
density of growth makes forests susceptible to disease, drought
and severe wildfires. Instead of restoring forests, these
wildfires destroy them and it can take decades to recover. This
radical change in our forests is the result of nearly a century of
well-intentioned but misguided management."liii
The Interface
One challenge Southern California faces regarding the wildfire hazard is from
the increasing number of houses being built on the urban/wildland interface.
Every year the growing population has expanded further and further into the
hills and mountains, including forest lands. The increased "interface"
between urban/suburban areas and the open spaces created by this
expansion has produced a significant increase in threats to life and property
from fires and has pushed existing fire protection systems beyond original or
current design and capability. Property owners in the interface are not aware
of the problems and threats they face. Therefore, many owners have done
very little to manage or offset fire hazards or risks on their own property.
Furthermore, human activities increase the incidence of fire ignition and
potential damage.
Fuel
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Fuel is the material that feeds a fire and is a key factor in wildfire behavior.
Fuel is classified by volume and by type. Volume is described in terms of "
fuel loading, " or the amount of available vegetative fuel.
The type of fuel also influences wildfire. Chaparral is a primary fuel of
Southern California wildfires. Chaparral habitat ranges in elevation from
near sea level to over 5,000' in Southern California. Chaparral communities
experience long dry summers and receive most of their annual precipitation
from Winter rains. Although chaparral is often considered as a single
species, there are two distinct types; hard chaparral and soft chaparral.
Within these two types are dozens of different plants, each with its own
particular characteristics.
"Fire has been important in the life cycle of chaparral communities for over 2
million years, however, the true nature of the "fire cycle" has been subject to
interpretation. In a period of 750 years, it generally thought that fire occurs
once every 65 years in coastal drainages and once every 30 to 35 years
inland. "liv
"The vegetation of chaparral communities has evolved to a point
it requires fire to spawn regeneration. Many species invite fire
through the production of plant materials with large surface-to-
volume ratios, volatile oils and through periodic die-back of
vegetation. These species have further adapted to possess
special reproductive mechanisms following fire. Several species
produce vast quantities of seeds which lie dormant until fire
triggers germination The parent plant which produces these
seeds defends itself from fire by a thick layer of bark which
allows enough of the plant to survive so that the plant can
crown sprout following the blaze. In general, chaparral
community plants have adapted to fire through the following
methods; a) fire induced flowering; b) bud production and
sprouting subsequent to fire; c) in-soil seed storage and fire
stimulated germination; and d) on plant seed storage and fire
stimulated dispersal."lv
An important element in understanding the danger of wildfire is the
availability of diverse fuels in the landscape, such as natural vegetation,
manmade structures and combustible materials. A house surrounded by
brushy growth rather than cleared space allows for greater continuity of fuel
and increases the fire's ability to spread. After decades of fire suppression
"dog-hair" thickets have accumulated, which enable high intensity fires to
flare and spread rapidly.
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Topography
Topography influences the movement of air, thereby directing a fire course.
For example, if the percentage of uphill slope doubles, the rate of spread in
wildfire will likely double. Gulches and canyons can funnel air and act as
chimneys, which intensify fire behavior and cause the fire to spread faster.
Solar heating of dry, south-facing slopes produces up slope drafts that can
complicate fire behavior. Unfortunately, hillsides with hazardous topographic
characteristics are also desirable residential areas in many communities.
This underscores the need for wildfire hazard mitigation and increased
education and outreach to homeowners living in interface areas.
Weather
Weather patterns combined with certain geographic locations can create a
favorable climate for wildfire activity. Areas where annual precipitation is
less than 30 inches per year are extremely fire susceptible.lvi High-risk areas
in Southern California share a hot, dry season in late summer and early fall
when high temperatures and low humidity favor fire activity. The so-called
"Santa Ana" winds, which are heated by compression as they flow down to
Southern California from Utah create a particularly high risk, as they can
rapidly spread what might otherwise be a small fire.
Drought
Recent concerns about the effects of climate change, particularly drought,
are contributing to concerns about wildfire vulnerability. The term drought is
applied to a period in which an unusual scarcity of rain causes a serious
hydrological imbalance. Unusually dry winters, or significantly less rainfall
than normal, can lead to relatively drier conditions and leave reservoirs and
water tables lower. Drought leads to problems with irrigation and may
contribute to additional fires, or additional difficulties in fighting fires.
Development
Growth and development in scrubland and forested areas is increasing the
number of human-made structures in Southern California interface areas.
Wildfire has an effect on development, yet development can also influence
wildfire. Owners often prefer homes that are private, have scenic views, are
nestled in vegetation and use natural materials. A private setting may be far
from public roads, or hidden behind a narrow, curving driveway. These
conditions, however, make evacuation and fire fighting difficult. The scenic
views found along mountain ridges can also mean areas of dangerous
topography. Natural vegetation contributes to scenic beauty, but it may also
provide a ready trail of fuel leading a fire directly to the combustible fuels of
the home itself.
WILDFIRE HAZARD ASSESSMENT
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Wildfire Hazard Identification
Wildfire hazard areas are commonly identified in regions of the
wildland/urban interface. Ranges of the wildfire hazard are further
determined by the ease of fire ignition due to natural or human conditions
and the difficulty of fire suppression. The wildfire hazard is also magnified by
several factors related to fire suppression/control such as the surrounding
fuel load, weather, topography and property characteristics. Generally,
hazard identification rating systems are based on weighted factors of fuels,
weather and topography.
Table 2.? illustrates a rating system to identify wildfire hazard risk (with a
score of 3 equaling the most danger and a score of 1 equaling the least
danger.)
Table 2.8 Sample Hazard Identification Rating System
Category Indicator Rati ng
Roads and Signage Steep; narrow; poorly signed 3
One or two of the above 2
Meets all requirements 1
Water Supply None, except domestic 3
Hydrant, tank, or pool over 500 feet away 2
Hydrant, tank, or pool within 500 feet 1
Location of the Top of steep slope with brush/grass below 3
Structure Mid-slope with clearance 2
Level with lawn, or watered groundcover 1
Exterior Combustible roofing, open eaves, Combustible 3
Construction siding
One or two of the above 2
Non-combustible roof, boxed eaves, non- 1
combustible siding
In order to determine the "base hazard factor" of specific wildfire hazard sites
and interface regions, several factors must be taken into account. Categories
used to assess the base hazard factor include:
Topographic location, characteristics and fuels;
Site/building construction and design;
Site/region fuel profile (landscaping);
Defensible space;
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Accessibility;
Fire protection response; and
Water availability.
The use of Geographic Information System (GIS) technology in recent years
has been a great asset to fire hazard assessment, allowing further integration
of fuels, weather and topography data for such ends as fire behavior
prediction, watershed evaluation, mitigation strategies and hazard mapping.
Vulnerability and Risk
Southern California residents are served by a variety of local fire
departments as well as county, state and federal fire resources. Data that
includes the location of interface areas in the county can be used to assess
the population and total value of property at risk from wildfire and direct
these fire agencies in fire prevention and response. Santa Monica does not
have an urban interface with the surrounding mountains, lessing the risk of
wildfire.
Key factors included in assessing wildfire risk include ignition sources,
building materials and design, community design, structural density, slope,
vegetative fuel, fire occurrence and weather, as well as occurrences of
drought.
The National Wildland/Urban Fire Protection Program has developed the
Wildland/Urban Fire Hazard Assessment Methodology tool for communities to
assess their risk to wildfire. For more information on wildfire hazard
assessment refer to http://www.Firewise.org.
COMMUNITY WILDFIRE ISSUES
What is Susceptible to Wildfire?
Growth and Development in the Interface
The hills and mountainous areas of Southern California are considered to be
interface areas. The development of homes and other structures is
encroaching onto the wildlands and is expanding the wildland/urban
interface. The interface neighborhoods are characterized by a diverse
mixture of varying housing structures, development patterns, ornamental
and natural vegetation and natural fuels.
In the event of a wildfire, vegetation, structures and other flammables can
merge into unwieldy and unpredictable events. Factors important to the
fighting of such fires include access, firebreaks, proximity of water sources,
distance from a fire station and available firefighting personnel and
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equipment. Reviewing past wildland/urban interface fires shows that many
structures are destroyed or damaged for one or more of the following
reasons:
Combustible roofing material;
Wood construction;
Structures with no defensible space;
Fire department with poor access to structures;
Subdivisions located in heavy natural fuel types;
Structures located on steep slopes covered with flammable vegetation;
Limited water supply; and
Winds over 30 miles per hour.
Road Access
Road access is a major issue for all emergency service providers. As
development encroaches into the rural areas of the county, the number of
houses without adequate turn-around space is increasing. In many areas,
there is not adequate space for emergency vehicle turnarounds in single-
family residential neighborhoods, causing emergency workers to have
difficulty doing their jobs because they cannot access houses. As fire trucks
are large, firefighters are challenged by narrow roads and limited access,
When there is inadequate turn around space, the fire fighters can only work
to remove the occupants, but cannot safely remain to save the threatened
structures.
Water Supply
Fire fighters in remote and rural areas are faced by limited water supply and
lack of hydrant taps. Rural areas are characteristically outfitted with small
diameter pipe water systems, inadequate for providing sustained fire fighting
flows.
Interface Fire Education Programs and Enforcement
Fire protection in urban/wildland interface areas may rely heavily more on
the landowner's personal initiative to take measures to protect his or her own
property. Therefore, public education and awareness may playa greater role
in interface areas. In those areas with strict fire codes, property owners who
are resist maintaining the minimum brush clearances may be cited for failure
to clear brush.
The Need for Mitigation Programs
Continued development into the interface areas will have growing impacts on
the wildland/urban interface. Periodically, the historical losses from wildfires
in Southern California have been catastrophic, with deadly and expensive
fires going back decades. The continued growth and development increases
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the public need for natural hazards mitigation planning in Southern
California.
Wildfire Mitigation Activities
Existing mitigation activities include current mitigation programs and
activities that are being implemented by county, regional, state, or federal
agencies or organizations.
Local Programs
In Southern California there are dozens of independent local fire departments
as well as large county wide consolidated fire districts. Although each district
or department is responsible for fire related issues in specific geographic
areas, they work together to keep Southern California residents safe from
fire. Although fire agencies work together to fight urban/wildland interface
fires, each separate agency may have a somwhat different set of codes to
enforce for mitigation activities.
The fire departments and districts provide essential public services in the
communities they serve and their duties far surpass extinguishing fires. Most
of the districts and departments provide other services to their jurisdictions,
including Emergency Medical Services who can begin treatment and stabilize
sick and injured patients in emergency situations. All of the fire service
providers in the county are dedicated to fire prevention and use their
resources to educate the public to reduce the threat of the fire hazard,
especially in the wildland/urban interface. Fire prevention professionals
throughout the county have taken the lead in providing many useful and
educational services to Southern California residents, such as:
Home fire safety inspection;
Assistance developing home fire escape plans;
Business Inspections;
Citizen Emergency Response Team (CERT) training;
Fire cause determination;
Counseling for juvenile fire-setters;
Teaching fire prevention in schools;
Coordinating educational programs with other agencies, hospitals and
schools; and
Answering citizens' questions regarding fire hazards.
The Threat of Urban Conflagration
Although communities without an urban/wildland interface are much less
likely to experience a catastrophic fire, in Southern California there is a
scenario where any community might be exposed to an urban conflagration
similar to the fires that occurred following the 1906 San Francisco
earthquake.
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"Large fires following an earthquake in an urban region are
relatively rare phenomena, but have occasionally been of
catastrophic proportions. The two largest peace-time urban
fires in history, 1906 San Francisco and 1923 Tokyo, were both
caused by earthquakes.
The fact that fire following earthquake has been little researched
or considered in the United States is particularly surprising when
one realizes that the conflagration in San Francisco after the
1906 earthquake was the single largest urban fire, and the
single largest earthquake loss, in U.S. history. The loss over
three days of more than 28,000 buildings within an area of 12
km2 was staggering: $250 million in 1906 dollars, or about $5
billion at today's prices.
The 1989 Loma Prieta Earthquake, the 1991 Oakland hills fire,
and Japan"s recent Hokkaido Nansei-oki Earthquake all
demonstrate the current, real possibility of a large fire, such as
a fire following an earthquake, developing into a conflagration.
In the United States, all the elements that would hamper fire-
fighting capabilities are present: density of wooden structures,
limited personnel and equipment to address multiple fires,
debris blocking the access of fire-fighting equipment, and a
limited water supply."lvii
This in Southern California, this scenario highlights the need for fire
mitigation activity in all sectors of the region, urban/wildland interface or not.
Federal Programs
The role of the federal land managing agencies in the wildland /urban
interface is reducing fuel hazards on the lands they administer; cooperating
in prevention and education programs; providing technical and financial
assistance; and developing agreements, partnerships and relationships with
property owners, local protection agencies, states and other stakeholders in
wildland/urban interface areas. These relationships focus on activities before
a fire occurs, which render structures and communities safer and better able
to survive a fire occurrence.
Federal Emergency Management Agency (FEMA) Programs FEMA is directly
responsible for providing fire suppression assistance grants and, in certain
cases, major disaster assistance and hazard mitigation grants in response to
fires. The role of FEMA in the wildland /urban interface is to encourage
comprehensive disaster preparedness plans and programs, increase the
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capability of state and local governments and provide for a greater
understanding of FEMA programs at the federal, state and local levels.lviii
Fire Suppression Assistance Grants
Fire Suppression Assistance Grants may be provided to a state with an
approved hazard mitigation plan for the suppression of a forest or grassland
fire that threatens to become a major disaster on public or private lands.
These grants are provided to protect life and improved property and
encourage the development and implementation of viable multi-hazard
mitigation measures and provide training to clarify FEMA's programs. The
grant may include funds for equipment, supplies and personnel. A Fire
Suppression Assistance Grant is the form of assistance most often provided
by FEMA to a state for a fire. The grants are cost-shared with states. FEMA's
US Fire Administration (USFA) provides public education materials addressing
wildland/urban interface issues and the USFA's National Fire Academy
provides training programs.
National Wildland/Urban Interface Fire Protection Program
Federal agencies can use the National Wildland/Urban Interface Fire
Protection Program to focus on wildland/urban interface fire protection issues
and actions. The Western Governors' Association (WGA) can act as a catalyst
to involve state agencies, as well as local and private stakeholders, with the
objective of developing an implementation plan to achieve a uniform,
integrated national approach to hazard and risk assessment and fire
prevention and protection in the wildland/urban interface. The program helps
states develop viable and comprehensive wildland fire mitigation plans and
performance-based partnerships.
U.S. Forest Service
The U. S. Forest Service (USFS) is involved in a fuel-loading program
implemented to assess fuels and reduce hazardous bUildup on forest lands.
The USFS is a cooperating agency and, while it has little to no jurisdiction in
the lower valleys, it has an interest in preventing fires in the interface, as
fires often burn up the hills and into the higher elevation US forest lands.
Other Mitigation Programs and Activities
Some areas of the country are facing wildland/urban issues collaboratively.
These are model programs that include local solutions. Summit County,
Colorado, has developed a hazard and risk assessment process that mitigates
hazards through zoning requirements. In California, the Los Angeles County
Fire Department has retrofitted more than 100 fire engines with fire
retardant foam capability and Orange County is evaluating a pilot insurance
grading and rating schedule specific to the wildland/urban interface. All are
examples successful programs that demonstrate the value of pre-suppression
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and prevention efforts when combined with property owner support to
mitigate hazards within the wildland/urban interface.
Firewise
Firewise is a program developed within the National Wildland/ Urban
Interface Fire Protection Program and it is the primary federal program
addressing interface fire. It is administered through the National Wildfire
Coordinating Group whose extensive list of participants includes a wide range
of federal agencies. The program is intended to empower planners and
decision makers at the local level. Through conferences and information
dissemination, Firewise increases support for interface wildfire mitigation by
educating professionals and the general public about hazard evaluation and
policy implementation techniques. Firewise offers online wildfire protection
information and checklists, as well as listings of other publications, videos
and conferences. The interactive home page allows users to ask fire
protection experts questions and to register for new information as it
becomes available.
FireFree Program
FireFree is a unique private/public program for interface wildfire mitigation
involving partnerships between an insurance company and local government
agencies. It is an example of an effective non-regulatory approach to hazard
mitigation. Originating in Bend, Oregon, the program was developed in
response to the city's "Skeleton Fire" of 1996, which burned over 17,000
acres and damaged or destroyed 30 homes and structures. Bend sought to
create a new kind of public education initiative that emphasized local
involvement. SAFECO Insurance Corporation was a willing collaborator in
this effort. Bend's pilot program included:
1. A short video production featuring local citizens as actors, made
available at local video stores, libraries and fire stations;
2. Two city-wide yard debris removal events;
3. A 3D-minute program on a model FireFree home, aired on a local cable
television station; and
4. Distribution of brochures, featuring a property owner evaluation
checklist and a listing of fire-resistant indigenous plants.
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WILDFIRE RESOURCE DIRECTORY
Local Resources
Santa Monica Fire Department
333 Olympic Drive, 2nd Floor
Santa Monica, CA 90401
Telephone: 310.458-8651
http://santamonicafire.org/index.htm
Cou nty Resou rces
Los Angeles County Fire Department
1320 N. Eastern Ave.
Los Angeles, CA., 90063
Telephone: 323.881.2411
http://www.lacofd.org/default.htm
State Resources
California Division of Forestry & Fire Protection
1416 9th Street
PO Box 944246
Sacramento California 94244-2460
(916)653-5123
http://www.fire.ca .gov/php/index. php
Office of the State Fire Marshal (OSFM)
1131 "S" Street
Sacramento, CA 95814
PO Box 944246
Sacramento, CA 94244-2460
Tel. (916) 445-8200
Fax. (916) 445-8509
Federal Resources and Programs
Federal Wildland Fire Policy, Wildland/Urban Interface Protection
This is a report describing federal policy and interface fire. Areas of
needed improvement are identified and addressed through
recommended goals and actions.
http://www.fs.fed.us/land/wdfire7c.htm
National Fire Protection Association (N FPA)
This is the principal federal agency involved in the National
Wildland/Urban Interface Fire Protection Initiative. NFPA has
information on the Initiatives programs and documents.
Public Fire Protection Division
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1 Battery March Park.
P.O. Box 9101
Quincy, MA 02269-9101
Phone: (617) 770-3000
National Interagency Fire Center (NIFC)
The NIFC in Boise, Idaho is the nation's support center for wildland
firefighting. Seven federal agencies work together to coordinate and
support wildland fire and disaster operations. These agencies include
the Bureau of Indian Affairs, Bureau of Land Management, Forest
Service, Fish and Wildlife Service, National Park Service, National
Weather Service and Office of Aircraft
National Interagency Fire Center
3833 S. Development Ave.
Boise, Idaho 83705
208-387-5512
http://www.nifc,gov/
United States Fire Administration (USFA) of the Federal Emergency
Management Agency (FEMA)
As an entity of the Federal Emergency Management Agency, the
mission of the USFA is to reduce life and economic losses due to fire
and related emergencies through leadership, advocacy, coordination
and support.
USFA, Planning Branch, Mitigation Directorate
16825 S. Seton Ave.
Emmitsburg, MD 21727
(301) 447-1000
http://www.fema.gov/hazards/fires/wildfires.shtm - Wildfire Mitigation
http://www.usfa.fema.gov/index.htm - U.S. Fire Administration
Additional Resources
Firewise - The National Wildland/Urban Interface Fire program
Firewise maintains a Website designed for people who live in wildfire
prone areas, but it also can be of use to local planners and decision
makers. The site offers online wildfire protection information and
checklists, as well as listings of other publications, videos and
conferences.
Firewise
1 Battery March Park.
P.O. Box 9101
Quincy, MA 02269-9101
Phone: (617) 770-3000
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http://www.firewise.org/
Publications
National Fire Protection Association Standard 299: Protection of Life and
Property from Wildfire, National Wildland/Urban Interface Fire Protection
Program, (1991), National Fire Protection Association, Washington, D.
This document, developed by the NFPA Forest and Rural Fire
Protection Committee, provides criteria for fire agencies, land use
planners, architects, developers and local governments to use in the
development of areas that may be threatened by wildfire. To obtain
this resource:
National Fire Protection Association Publications
(800) 344-3555
http://www.nfpa.org or http://www.firewise.org
An International Collection of Wildland- Urban Interface Resource Materials
(Information Report NOR- 344). Hirsch, K., Pinedo, M., & Greenlee, J.
(1996). Edmonton, Alberta: Canadian Forest Service.
This is a comprehensive bibliography of interface wildfire materials.
Over 2,000 resources are included, grouped under the categories of
general and technical reports, newspaper articles and public education
materials. The citation format allows the reader to obtain most items
through a library or directly from the publisher. The bibliography is
available in hard copy or diskette at no cost. It is also available in
downloadable PDF form.
Canadian Forest Service, Northern Forestry Centre, I-Zone Series
Phone: (780) 435-7210
http://www.prefire.ucfpl.ucop.edu/uwibib.htm
Wildland/Urban Interface Fire Hazard Assessment Methodology.
National Wildland/Urban Interface Fire Protection Program, (1998).
NFPA, Washington, D.C.
Firewise (NFPA Public Fire Protection Division)
Phone: (617) 984-7486
http://www.firewise.org
Fire Protection in the Wildland/Urban Interface: Everyone's Responsibility.
National Wildland/Urban Interface Fire Protection Program, (1998).
Washington, D.
Firewise (NFPA Public Fire Protection Division)
Phone: (617) 984-7486
http://www.firewise, org
Wildfire Endnotes
1 http://www.fire.ca .gov/php/2003fireseasonstats_ v2.asp
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2
http://www.fire.ca .gov/php/fire_er _content/downloads/2003LargeFires. pdf
3
http://www.usgs.gov/public/press/public_affairs/press_releases/pr1805m.htm I
4
http://www.nifc.gov/stats/wildlandfirestats.html
5
http://research . ya Ie .edu/g isf/ assets/pdf/ppf/wi Idfire_report. pdf
6
Planning for Natural Hazards: The Oregon Technical Resource Guide, (July 2000)
Department of Land Conservation and Development
7
http://www.usgs.gov/public/press/public_affairs/press_releases/pr1805m.htm I
8
Overgrown Forests Require Preventive Measures, By Gale A. Norton (Secretary of the
Interior), USA Today Editorial, August 21, 2002
9
http://www.coastal.ca.gov/fire/ucsbfire.html
10
Ibid
11
Planning for Natural Hazards: The Oregon Technical Resource Guide, (July 2000),
Department of Land Conservation and Development
12
http://www.eqe.com/publications/revf93/firefoll.htm
12
Source: National Interagency Fire Center, Boise ID and California Division of Forestry,
Riverside Fire Lab.
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2.6 Severe Windstorm/Thunderstorm
Table of Contents
Why Are Windstorms a Threat to Southern California? ...........................152
Windstorm Characteristics................................................................. 152
Loca I History of Wi ndstorm Events ..................................................... 155
Windstorm Hazard Identification......................................................... 157
What Is S uscepti ble to Wi ndstorm? .... .... .... .... .... .. .. .. .. .. .. .. .... .... .... .... ... 158
Existing Windstorm Mitigation Activities............................................... 160
Windstorm Resource Directory ........................................................... 162
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Why are Severe Windstorms a
Threat to the City of Santa Monica?
Severe wind storms pose a significant
risk to life and property in the region by
creating conditions that disrupt
essential systems such as public
utilities, telecommunications, and
transportation routes. High winds can
and do occasionally cause tornado-like
damage to local homes and businesses.
Severe windstorms can present a very
destabilizing effect on the dry brush
that covers local hillsides and urban
wildland interface areas. High winds
can have destructive impacts,
especially to trees, power lines, and
utility services.
Great
Buln
Map 2.7 Wind patterns in Southern
California (NASA's "Observatorium")
WINDSTORM CHARACTERISTICS IN SOUTHERN CALIFORNIA
Santa Ana Winds and Tornado-Like Wind Activity
Based on local history, most incidents of high wind in the City of Santa
Monica are the result of the Santa Ana wind conditions. While high impact
wind incidents are not frequent in the area, significant Santa Ana Wind
events and sporadic tornado activity have been known to negatively impact
the local community.
What are Santa Ana Winds?
"Santa Ana winds are generally defined as warm, dry winds that blow from
the east or northeast (offshore). These winds occur below the passes and
canyons of the coastal ranges of Southern California and in the Los Angeles
basin. Santa Ana winds often blow with exceptional speed in the Santa Ana
Canyon (the canyon from which it derives its name). Forecasters at the
National Weather Service offices in Oxnard and San Diego usually place
speed minimums on these winds and reserve the use of "Santa Ana" for
winds greater than 25 knots."lix These winds accelerate to speeds of 35
knots as they move through canyons and passes, with gusts to 50 or even 60
knots.
"The complex topography of Southern California combined with various
atmospheric conditions create numerous scenarios that may cause
widespread or isolated Santa Ana events. Commonly, Santa Ana winds
develop when a region of high pressure builds over the Great Basin (the high
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plateau east of the Sierra mountains and west of the Rocky mountains
including most of Nevada and Utah). Clockwise circulation around the center
of this high pressure area forces air downslope from the high plateau. The air
warms as it descends toward the California coast at the rate of 5 degrees F
per 1000 feet due to compressional heating. Thus, compressional heating
provides the primary source of warming. The air is dry since it originated in
the desert, and it dries out even more as it is heated."lx
These regional winds typically occur from October to March, and, according
to most accounts are named either for the Santa Ana River Valley where they
originate or for the Santa Ana Canyon, southeast of Los Angeles, where they
pick up speed.
What are Tornados?
Tornadoes are spawned when there is warm, moist air near the ground, cool
air aloft, and winds that speed up and change direction. An obstruction, such
as a house, in the path of the wind causes it to change direction. This
change increases pressure on parts of the house, and the combination of
increased pressures and fluctuating wind speeds creates stresses that
frequently cause structural failures.
In order to measure the intensity and wind strength of a tornado, Dr. T.
Theodore Fujita developed the Fujita Tornado Damage Scale. This scale
compares the estimated wind velocity with the corresponding amount of
suspected damage. The scale measures six classifications of tornadoes with
increasing magnitude from an "FO" tornado to a "F6+" tornado.
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Table 2.9 Fujita Tornado Damage Scale
Wind
Scale Esti mate Typical Damage
(mph)
FO < 73 Light damage. Some damage to chimneys and TV antennas;
breaks twigs off trees; pushes over shallow-rooted trees.
Moderate damage. Peels surface off roofs; windows broken;
Fl 73-112 light trailer houses pushed or overturned; some trees
uprooted or snapped; moving automobiles pushed off the
road. 74 mph is the beginning of hurricane wind speed.
Considerable damage. Roofs torn off frame houses leaving
strong upright walls; weak buildings in rural areas
F2 113-157 demolished; trailer houses destroyed; large trees snapped or
uprooted; railroad boxcars pushed over; light object missiles
generated; cars blown off highway.
Severe damage. Roofs and some walls torn off frame
houses; some rural buildings completely demolished; trains
F3 158-206 overturned; steel-framed hangar-warehouse-type structures
torn; cars lifted off the ground; most trees in a forest
uprooted snapped, or leveled.
Devastating damage. Whole frame houses leveled, leaving
piles of debris; steel structures badly damaged; trees
F4 207-260 debarked by small flying debris; cars and trains thrown some
distances or rolled considerable distances; large missiles
generated.
Incredible damage. Whole frame houses tossed off
F5 261-318 foundations; steel-reinforced concrete structures badly
damaged; automobile-sized missiles generated; trees
debarked; incredible phenomena can occur.
Inconceivable damage. Should a tornado with the
F6- 319 to maximum wind speed in excess of F5 occur, the extent and
F12 sonic types of damage may not be conceived. A number of missiles
such as iceboxes, water heaters, storage tanks, automobiles,
etc. will create serious secondary damage on structures.
Source: http://weather.latimes.com/tornadoFAO.asp
Microbursts
Unlike tornados, microbursts, are strong, damaging winds which strike the
ground and often give the impression a tornado has struck. They frequently
occur during intense thunderstorms. The origin of a microburst is downward
moving air from a thunderstorm's core. But unlike a tornado, they affect only a
rather small area.
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University of Chicago storm researcher Dr Ted Fujita first coined the term
"downburst" to describe strong, downdraft winds flowing out of a thunderstorm
cell that he believed were responsible for the crash of Eastern Airlines Flight 66
in June of 1975.lxi
A downburst is a straight-direction surface wind in excess of 39 mph caused by a
small-scale, strong downdraft from the base of convective thundershowers and
thunderstorms. In later investigations into the phenomena he defined two sub-
categories of downbursts: the larger macrobursts and small microbursts.lxii
Macrobursts are downbursts with winds up to 117 mph which spread across a
path greater than 2.5 miles wide at the surface and which last from 5 to 30
minutes. The microburst, on the other hand is confined to an even smaller area,
less than 2.5 miles in diameter from the initial point of downdraft impact. An
intense microburst can result in damaging winds near 270 km/hr (170 mph) and
often last for less than five minutes.lxiii
"Downbursts of all sizes descend from the upper regions of severe
thunderstorms when the air accelerates downward through either
exceptionally strong evaporative cooling or by very heavy rain which
drags dry air down with it. When the rapidly descending air strikes
the ground, it spreads outward in all directions, like a fast-running
faucet stream hitting the sink bottom.
When the microburst wind hits an object on the ground such as a
house, garage or tree, it can flatten the buildings and strip limbs
and branches from the tree. After striking the ground, the powerful
outward running gust can wreak further havoc along its path.
Damage associated with a microburst is often mistaken for the work
of a tornado, particularly directly under the microburst. However,
damage patterns away from the impact area are characteristic of
straight-line winds rather than the twisted pattern of tornado
damage."lxiV
Tornados, like those that occur every year in the Midwest and Southeast parts of
the United States, are a rare phenomenon in most of California, with most
tornado-like activity coming from micro-bursts.
LOCAL HISTORY OF WINDSTORM EVENTS
Tornados
The south coastal region of California, including the Los Angeles Basin, has the
greatest incidence of tornadoes in the state. In the period from 1950 to 1992,
the basin had 99 confirmed tornadoes. According to Blier and Battan (1994),
this area has a tornadic incidence similar to that of the State of Oklahoma.
However, these researchers go on to point out that the size, severity and
duration of California tornadoes is less than those common to the plains states,
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and the tornado count in the Golden State may be inflated due to inaccuracies
within the database. Nevertheless, the fact that tornadoes occur with great
frequency in a very densely populated urban area makes the occurrence of
tornadoes in the Los Angeles Basin particularly relevant.
Unlike their Plains counterparts, southern California tornadoes occur mainly in
the winter. Of the 99 tornadoes that were reported in the Los Angeles Basin
between 1950 and 1992, the vast majority (83) occurred in the months
November through March. March had the highest number of incidents (22). The
fact that few tornadoes occur in the Los Angeles Basin during the warm season is
primarily due to the stabilizing effect of the marine layer, and the lack of
dynamic forcing during the warmer months.
Roughly a quarter of the tornadoes listed by Blier and Battan originated as
waterspouts over either Santa Monica Bay or San Pedro Channel. There were
many more waterspouts that never made landfall; these were not included in the
tornado count.
The cause of many, if not most, of the Los Angeles Basin tornadoes seems to be
linked to the terrain layout of the basin. Hales specifically mentioned the natural
curvature of the shoreline and the location of the coastal mountains. Due to
frictional and barrier flow effects, a convergent cyclonic wind pattern is
established in the vicinity where most L.A. tornadoes occur. Blier and Battan
discussed several features that require further investigation, including
convergence to the lee of the Palos Verdes Peninsula and Santa Catalina Island.
In the 1997-98 E/ Nino episode, the Pacific storm track was located over
southern California for much of the winter season. This produced a number of
days in which Hale's criteria were approximated over the Los Angeles Basin and
adjacent waters. In that season, there were over twenty days in which either
waterspouts, funnel clouds or tornadoes were reported-including 30 separate
sightings. Two tornadoes touched down within the City of Long Beach.
Thunderstorms
A mass of warm, moist subtropical air occasionally overlies the Los Angeles Basin
during the mid to late summer. The subtropical airmass originates in Mexico,
then moves northwest into Arizona usually around the first week in July. The
humid, sultry air, with its characteristic high dewpoints, frequently pulses into
southern California deserts and occasionally extends into the coastal plain.
During these periods, thunderstorms form mostly over the mountains of
southern California in the afternoons, then occasionally meander over the coastal
lowlands during evening and nighttime hours.
The mean number of days per year on which thunderstorms occur (i.e. days on
which thunder is heard, regardless of precipitation) is 4.1 in the downtown Los
Angeles area.
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Because they are an infrequent visitor to the heavily populated southern
California coast, thunderstorms are very notable when they do occur. Even when
they produce only light precipitation, they can be a source of serious
inconvenience by wetting an area that had been dry for weeks, or even months.
Also, they may cause shifting surface winds with local gusts to 50 miles per hour
or more. This combination, more or less innocuous in other parts of the United
States, is actually dangerous in Los Angeles. The inevitable result of even small
summer thunderstorms is a rash of highway accidents, freeway traffic jams and
local power outages.
During one afternoon in the spring of 1999 when scattered thunderstorms
occurred across the Los Angeles Basin, a cluster of traffic accidents was
reported, including one 70-car pileup on
Interstate 10.
WINDSTORM HAZARD ASSESSMENT
Great
Buln
Hazard Identification
A windstorm event in the region can
range from short term microburst
activity lasting only minutes to a long
duration Santa Ana wind condition that
can last for several days as in the case
of the January 2003 Santa Ana wind
event. Windstorms in the City of Santa
Monica area can cause extensive
damage including heavy tree stands,
exposed coastal properties, road and
highway infrastructure, and critical
utility facilities. Heavy tourist traffic on the State and Local beach property is at
great risk during windstorm activity.
The map shows clearly the direction of the Santa Ana winds as they travel from
the stable, high-pressure weather system called the Great Basin High through
the canyons and towards the low-pressure system off the Pacific. Clearly the
area of the City of Santa Monica is in the direct path of the ocean-bound Santa
Ana winds.
We can deduce the common windstorm impact areas including impacts on life,
property, utilities, infrastructure and transportation. Additionally, if a windstorm
disrupts power to local residential communities, the American Red Cross and City
resources might be called upon for care and shelter duties. Displacing residents
and utilizing City resources for shelter staffing and disaster cleanup can cause an
economic hardship on the community.
COMMUNITY WINDSTORM ISSUES
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What is Susceptible to Windstorms?
Life and Property
Based on the history of the region, windstorm events can be expected, perhaps
annually, across widespread areas of the region which can be adversely impacted
during a windstorm event. This can result in the involvement of City of Santa
Monica emergency response personnel during a wide-ranging windstorm or
microburst tornadic activity. Both residential and commercial structures with
weak reinforcement are susceptible to damage. Wind pressure can create a
direct and frontal assault on a structure, pushing walls, doors, and windows
inward. Conversely, passing currents can create lift suction forces that pull
building components and surfaces outward. With extreme wind forces, the roof
or entire building can fail causing considerable damage.
Debris carried along by extreme winds can directly contribute to loss of life and
indirectly to the failure of protective building envelopes, siding, or walls. When
severe windstorms strike a community, downed trees, power lines, and damaged
property can be major hindrances to emergency response and disaster recovery.
The Beaufort Scale below, coined and developed by Sir Francis Beaufort in 1805,
illustrates the effect that varying wind speed can have on sea swells and
structures:
Table 2.10 BEAUFORT SCALE
Beaufort Speed Wind Description - State of Sea - Effects on Land
Force (mph)
0 Less 1 Calm - Mirror-like - Smoke rises vertically
1 1-3 Light - Air Ripples look like scales; No crests of foam - Smoke
drift shows direction of wind, but wind vanes do not
Light Breeze - Small but pronounced wavelets; Crests do not
2 4-7 break - Wind vanes move; Leaves rustle; You can feel wind on
the face
Gentle Breeze - Large Wavelets; Crests break; Glassy foam; A
3 8-12 few whitecaps - Leaves and small twigs move constantly; Small,
light flags are extended
4 13-18 Moderate Breeze - Longer waves; Whitecaps - Wind lifts dust and
loose paper; Small branches move
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5 19-24 Fresh Breeze - Moderate, long waves; Many whitecaps; Some
spray - Small trees with leaves begin to move
Strong Breeze - Some large waves; Crests of white foam; Spray
6 25-31 - Large branches move; Telegraph wires whistle; Hard to hold
umbrellas
Near Gale - White foam from breaking waves blows in streaks
7 32-38 with the wind - Whole trees move; Resistance felt walking into
wind
Gale - Waves high and moderately long; Crests break into spin
8 39-46 drift, blowing foam in well marked streaks - Twigs and small
branches break off trees; Difficult to walk
Strong Gale - High waves with wave crests that tumble; Dense
9 47-54 streaks of foam in wind; Poor visibility from spray - Slight
structural damage
Storm - Very high waves with long, curling crests; Sea surface
10 55-63 appears white from blowing foam; Heavy tumbling of sea; Poor
visibility - Trees broken or uprooted; Considerable structural
damage
Violent Storm - Waves high enough to hide small and medium
11 64- 7 3 sized ships; Sea covered with patches of white foam; Edges of
wave crests blown into froth; Poor visibility - Seldom experienced
inland; Considerable structural damage
Hurricane - Sea white with spray. Foam and spray render
12 >74 visibility almost non-existent - Widespread damage. Very rarely
experienced on land in Southern California.
Source: http://www.compuweather.com/decoder-charts.html
Utilities
Historically, falling trees have been the major cause of power outages in the
region. Windstorms such as strong microbursts and Santa Ana Wind conditions
can cause flying debris and downed utility lines. For example, tree limbs
breaking in winds of only 45 mph can be thrown over 75 feet. As such, overhead
power lines can be damaged even in relatively minor windstorm events. Falling
trees can bring electric power lines down to the pavement, creating the
possibility of lethal electric shock. Rising population growth and new
infrastructure in the region creates a higher probability for damage to occur from
windstorms as more life and property are exposed to risk.
Infrastructure
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Windstorms can damage buildings, power lines, and other property and
infrastructure due to falling trees and branches. During wet winters, saturated
soils cause trees to become less stable and more vulnerable to uprooting from
high winds.
Windstorms can result in collapsed or damaged buildings or blocked roads and
bridges, damaged traffic signals, streetlights, and parks, among others. Roads
blocked by fallen trees during a windstorm may have severe consequences to
people who need access to emergency services. Emergency response operations
can be complicated when roads are blocked or when power supplies are
interrupted. Industry and commerce can suffer losses from interruptions in
electric services and from extended road closures. They can also sustain direct
losses to buildings, personnel, and other vital equipment. There are direct
consequences to the local economy resulting from windstorms related to both
physical damages and interrupted services.
Increased Fire Threat
Perhaps the greatest danger from windstorm activity in Southern California
comes from the combination of the Santa Ana winds with the major fires that
occur every few years in the urban/wildland interface. With the Santa Ana winds
driving the flames, the speed and reach of the flames is even greater than in
times of calm wind conditions. The higher fire hazard raised by a Santa Ana
wind condition requires that even more care and attention be paid to proper
brush clearances on property in the wildland/urban interface areas.
Tra nsportation
Windstorm activity can have an impact on local transportation in addition to the
problems caused by downed trees and electrical wires blocking streets and
highways. During periods of extremely strong Santa Ana winds, major highways
can be temporarily closed to truck and recreational vehicle traffic. However,
typically these disruptions are not long lasting, nor do they carry a severe long
term economic impact on the region.
Existing Windstorm Mitigation Activities
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As stated, one of the most common problems associated with windstorms is
power outage. High winds commonly occur during winter storms, and can cause
trees to bend, sag, or fail (tree limbs or entire trees), coming into contact with
nearby distribution power lines. Fallen trees can cause short-circuiting and
conductor overloading. Wind-induced damage to the power system causes
power outages to customers, incurs cost to make repairs, and in some cases can
lead to ignitions that start wild land fires.
One of the strongest and most widespread existing mitigation strategies pertains
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to tree clearance. Currently, California State Law requires utility companies to
maintain specific clearances (depending on the type of voltage running through
the line) between electric power lines and all vegetation.
Enforcement of the following California Public Resource Code Sections provides
gUidance on tree pruning regulations:lxv
4293: Power Line Clearance Required
4292: Power Line Hazard Reduction
4291: Reduction of Fire Hazards Around Buildings
4171: Public Nuisances
The following pertain to tree pruning regulations and are taken from the
California Code of Regulations:
Title 14: Minimum Clearance Provisions
Sections 1250-1258
General Industry Safety Orders
Title 8: Group 3: Articles 12, 13, 36, 37, 38
California Penal Code Section 385
Finally, the following California Public Utilities Commission section has additional
gUidance:
California Public Utilities Commission
General Order 95: Rule 35
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Homeowner Liability
Failure to allow a utility company to
comply with the law can result in
liability to the homeowner for
damages or injuries resulting from a
vegetation hazard.
Many insurance companies do not
cover these types of damages if the
policy owner has refused to allow the
hazard to be eliminated.
The power companies, in compliance
with the above regulations, collect
data about tree failures and their
impact on power lines. This
mitigation strategy assists the power company in preventing future tree failure.
From the collection of this data, the power company can advise residents as to
the most appropriate vegetative planting and pruning procedures. The following
chart depicts some of the tree failure data collected by Southern California
Edison in this comprehensive mitigation strategy:
WINDSTORM RESOURCE DIRECTORY
State Resources
California Division of Forestry & Fire Protection
1416 9th Street
PO Box 944246
Sacramento California 94244-2460
916-653-5123
http://www.fire.ca .gov/php/index.php
Federal Resources and Programs
National Weather Service
Los Angeles/Oxnard Weather Forecast Office
520 North Elevar Street
Oxnard, CA 93030
Forecast and weather info: 805-988-6610
Administrative issues: 805-988-6615
E-mail: Webmaster. LOX@noaa.gov
http://weather.noaa.gov/
Additional Resources
International Society of Arboriculture.
P.O. Box 3129
Champaign, IL 61826-3129
Phone: 217.355.9411
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Fax: 217.355.9516
Web: www.isa-arbor.com
E-mail: isa@isa-arbor.com
Publications
WINDSTORMS: Protect Your Family and Property from the Hazards of Violent
Windstorms
http://emd. wa .gov/5-prep/trng/pubed/Windstrm. pdf
Preparinq Your Home for Severe Windstorms is available from
http://www.chubb.com/personal/html/helpful_tips_home_windstorm.htm I
End Notes
1. htto:/ /nimbo.wrh. noaa .qov/Sandieqo/snawind. html
2. Ibid
3. Keith C. Heidorn at htto:/ /www.suite101.com/article.cfm/13646/100918.
June 1, 2003
4. Ibid
5. Ibid
6. Ibid
www.cpuc.ca .govjjs.asp
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