Earthquake Book


Guide to


Safety Before Earthquake

Published by

The California

Seismic Safety


State of





SSC No. 05-012005 Edition

Damage from magnitude 6.7 earthquake

Additional damage from aftershocks

Publishing Information

The Homeowner’s Guide to Earthquake Safety was developed and

published by the California Seismic Safety Commission. The guide was

prepared for publication by the staff of The Collaborative for Disaster

Mitigation, San Jose State University, One Washington Square, San

Jose, CA 95192-0082. It was distributed under the provisions of the

Library Distribution Act and Government Code Section 11096.

Copyrighted 2005 by the California Seismic Safety Commission

All rights reserved


This guide has been developed and adopted by the California Seismic

Safety Commission as required by Assembly Bill 2959, authored by

Assemblyman Johan Klehs (Chapter 1499, Statutes of 1990), and

Assembly Bill 200, authored by Assemblyman Dominic Cortese (Chapter

699, Statutes of 1991).

Ordering Information

Copies of this booklet are available from the California Seismic Safety

Commission, 1775 Creekside Oaks Drive, Suite 100, Sacramento, CA

95833. To order call (916) 263-5506 or download via our website at

On the cover:

Taken in Coalinga, California, the pictures of this single family home

show the destruction caused by the Coalinga Earthquake on May 2,

1983. The 6.7 magnitude earthquake inflicted severe damage to the

unreinforced masonry porch, forcing the occupants to evacuate.

Numerous aftershocks occurred within the next few days, causing

portions of the already weakened structure to collapse.

ii The Homeowner’s Guide to Earthquake Safety

This 2005 Edition of the Homeowner’s Guide to Earthquake

Safety replaces the 2002 Edition on July 1, 2005.




Your Home and the Law..............................2


Summary of Major California Laws.............4

Property Tax and Insurance........................5

Examples of Damage to Single Family



Damaging Earthquakes in California............7

Major Earthquake Faults in California..........8

Simplified Earthquake Shaking Potential Map

for California....................................9

ADDITIONAL RESOURCES............................10

EARTHQUAKE WEAKNESSES......................11

Unbraced Water Heaters..........................12

Home Not Anchored to Foundation.........14

Weak Cripple Walls..................................16

Pier and Post Foundations........................18

Unreinforced Masonry Foundations..........20

Homes Built on Steep Hillsides.................22

Unreinforced Masonry Walls....................24

Rooms over Garages...............................26




Unreinforced Masonry Chimneys.............28


Homes with Unique Designs....................31



GETTING THE WORK DONE..........................34









RESOURCE ORGANIZATIONS......................44



SAMPLE TAX EXCLUSION FORM.................49

The Homeowner’s Guide to Earthquake Safety iii


iv The Homeowner’s Guide to Earthquake Safety

Seismic Safety Commission

Lucille M. Jones, Ph.D., Chair, Seismology

Hon. Richard Alarcon, State Senate

(Chris Modrzejewski)

Hon. Carol Liu, State Assembly

(Donald Manning)

Lawrence T. Klein, Utilities

Mark Church, Local Government

Linden Nishinaga, P.E., City Government

Celestine Palmer, Insurance

Andrew A. Adelman, P.E., Cities/Building


Stan Moy, A.I.A., Architecture and Planning

Daniel Shapiro, S.E., Structural Engineering

Vacant, Mechanical Engineering

Bruce R. Clark, Ph.D., Geology

Vacant, County Government

Vacant, Emergency Services

Donald R. Parker, Vice Chairman, Fire


Jimmie R. Yee, Social Services

Vacant, Soils Engineering

Seismic Safety Commission Staff

Richard McCarthy, Executive Director

Robert Anderson

Karen Cogan

Henry Reyes

Henry Sepulveda

Fred Turner, Project Coordinator

Sue Celli

Rebecca Romo

Collaborative for Disaster Mitigation Staff

Guna Selvaduray, Ph.D., Executive Director

Patrick Chong, Webmaster

Crystal Carrera, Administrative Assistant

The Commission gratefully acknowledges

the assistance of the following:

American Red Cross

American Society of Home Inspectors

Association of Bay Area Governments

Building Education Center

California Association of Realtors

California Building Officials

California Council of the American Institute of


California Geological Survey

California Real Estate Inspection Association

California Governor’s Office of Emergency


City of Los Angeles

Earthquake Engineering Research Institute

Humboldt Earthquake Education Center

International Code Council


San Diego Association of Governments

Southern California Association of Governments

Southern California Association of Residential

Retrofit Professions

Southern California Gas Company/Sempra

Structural Engineers Association of California

Committee on Earthquake Safety Issues for Gas


Disclaimer: The effects, descriptions, recommendations, and

suggestions included in this document are intended to improve

earthquake preparedness; however, they do not guarantee the

safety of an individual or a structure. The Seismic Safety

Commission takes responsibility for the inclusion of material in

this document. The State of California, the Seismic Safety

Commission, and all contributors to this document do not

assume liability for any injury, death, property damage, loss of

revenue, or any other effect of an earthquake.


Earthquakes, especially major ones, are

dangerous, inevitable, and a fact of life in

California. Sooner or later another “big one” will



?? Occur without warning

?? Can be deadly and extremely destructive

?? Can occur at any time

As a current or potential owner of a home*, you

should be very concerned about the potential

danger to not only yourselves and your loved ones,

but also to your property.

The major threats posed by earthquakes are bodily

injuries and property damage, which can be

considerable and even catastrophic.

Most of the property damage caused by

earthquakes ends up being handled and paid for

by the homeowner.

?? Earthquakes have caused over $55 billion in

losses in California since 1971.

?? Large earthquakes in or near major urban

centers in California will disrupt the local

economy and can disrupt the economy of the

entire State.

However, proper earthquake preparation of your

home can:

?? Save lives

?? Reduce injuries

?? Reduce property damage

As a homeowner, you can significantly reduce

damage to your home by fixing a number of known

and common weaknesses.

The Homeowner’s Guide to Earthquake Safety 1

*For the purpose of this document, “home” includes

single family residences, duplexes, triplexes, and


This Booklet is designed to assist you in filling out

the Residential Earthquake Hazards Report (See

page 47) when you sell your home.

This booklet is also a good start to begin

strengthening your home against earthquake


It describes:

?? Common weaknesses that can result in your

home being damaged by earthquakes, and

?? Steps you can take to correct these


There are no guarantees of safety during

earthquakes, but properly constructed and

strengthened homes are far less likely to collapse

or be damaged during earthquakes. The California

Seismic Safety Commission advises you to act on

the suggestions outlined in this booklet and make

yourself, your family, and your home safer.

California State Law requires the

seller to:

?? Inform the buyer about known home

weaknesses (See Earthquake

Weaknesses, beginning on page 11).

?? Strap the water heater, reducing the

chance of it falling during an earthquake

and possibly causing gas and water lines to


?? Deliver a copy of this booklet to the buyer if

the home was built before 1960 (Your real

estate agent is required to give the seller a

copy of this booklet).

?? Deliver to buyers a Natural Hazards

Disclosure form (See page 4). The

disclosure will tell buyers whether the home

is in an Earthquake Fault Zone or in a

Seismic Hazard Zone (See page 38)

?? Complete the Residential Earthquake

Hazards Report, to be provided to the

buyer (See page 47).

California State Law does not require

the seller to:

?? Hire someone to evaluate your home.

?? Strengthen your home before selling it.

2 The Homeowner’s Guide to Earthquake Safety

This Booklet:

?? Describes the most common weaknesses

that can cause damage to homes, in the

event of an earthquake.

?? Enables the seller to meet the State Law

requiring this booklet be given to every

buyer of homes built before 1960.

?? Enables the seller to disclose to the buyer

the typical earthquake weaknesses in

homes built before 1960.

?? Provides the homeowner with basic

information about finding and fixing

earthquake-related weaknesses in the


?? Provides general information about

earthquake risks and directions for finding

more information on earthquake safety.



If You Are Selling

Before you sell your house, the following steps

are recommended:

?? If you list your house for sale through a real

estate broker or agent, give the agent the

completed disclosure form (See page 47)

as soon as practical. Your agent can give

the booklet and the form to the buyer for


?? You are not required to hire someone to

answer the questions on the disclosure


?? You are not required to remove siding,

drywall, or plaster to answer the questions.

?? You are not required to fix the weaknesses

before you sell your home.

?? However, if you wish, you may get

assistance from a certified home inspector,

or a licensed contractor, architect, or


?? Keep a copy of the form, signed by the

buyer, as evidence that you have complied

with the earthquake disclosure


You may find that you will get a better price for

your house if you strengthen earthquake

weaknesses before you sell.

If You Are Buying

Before you agree to buy a house, consider the

following recommendations:

?? Have a certified home inspector, licensed

building contractor, architect, or engineer

inspect the house and give you an opinion

regarding existing earthquake weaknesses

and an estimate of costs to strengthen

these weaknesses.

?? Consider the location of the home: Is it in or

near an Earthquake Fault Zone or in an

area where it might be damaged by a

landslide, liquefaction, or a tsunami? You

may wish to hire a licensed geotechnical

engineer and/or engineering geologist to

check the stability of the land under the


?? Negotiate the cost of strengthening, if any

is required, with the seller. The law does

not require either you or the seller to

strengthen the home, but if these weaknesses

are not fixed, you may find that

repair costs after a damaging earthquake

can amount to more than your equity in the


The Homeowner’s Guide to Earthquake Safety 3

4 The Homeowner’s Guide to Earthquake Safety

Delivering this guide

Sellers of homes built before 1960, with one to four

units of conventional light-frame construction,

must deliver to the buyer, “as soon as practicable

before the transfer,” a copy of The Homeowner’s

Guide to Earthquake Safety (this booklet) and

disclose certain earthquake deficiencies according

to Government Code, Section 8897.1 to 8897.4.

The seller’s real estate agent must provide the

seller with a copy of this booklet to give to the

buyer. This is also specified in Government Code,

Section 8897.5.

Water heater bracing

All water heaters are required to be anchored or

strapped to resist falling during an earthquake.

The seller must certify to the potential buyer that

the water heater is properly braced in accordance

with Health and Safety Code, Section 19211.

Disclosing weaknesses

Sellers of real property must disclose known

defects and deficiencies in the property—including

earthquake weaknesses and hazards—to

prospective buyers in accordance with Civil Code,

Section 1102 and following sections.

Disclosing natural hazards

Sellers of real property must disclose whether the

property is within any of the seven mapped natural

hazard areas, including the earthquake fault,

potential landslide and potential liquefaction areas.

The required Natural Hazards Disclosure Form can



Full wording of all California codes is available at:

be found in Civil Code, Section 1103 and

following sections. When filled out, this statutory

form will reveal whether the home is within a

mapped geologic, flood or hazard area.

Earthquake faults

The Alquist-Priolo Earthquake Fault Zoning Act

prohibits building for human occupancy astride

active faults. Public Resources Code, Section

2621 and following sections, requires sellers of

existing residences to disclose to potential buyers

on a Natural Hazards Disclosure Form if the

property is located in a designated fault zone.

Landslide and liquefaction

The Seismic Hazards Mapping Act requires the

state to prepare maps of the zones in California

most susceptible to landslide and liquefaction

hazards during earthquakes. Public Resources

Code, Section 2694 and following sections, states

that sellers must disclose to buyers, on a Natural

Hazards Disclosure Form, whether the property is

in such a zone, after the map for that area has

been issued officially.

Publishing this guide

The Seismic Safety Commission is required to

develop, adopt, update, and publish The

Homeowner’s Guide to Earthquake Safety

containing information on geologic and seismic

hazards, explanations of structural and

nonstructural earthquake hazards, and

recommendations for mitigating these hazards,

as required by the Business and Professions

Code, Section 10149.

Property Tax Reappraisal Exclusion

California law allows homeowners to strengthen

their homes with approved seismic strengthening

techniques without the improvement being

included in reappraisals that usually raise the

property value and the tax owed, according to the

Revenue and Tax Code, Section 74.5.

If you make an addition, such as a swimming pool

or a new den to your home, your property tax bill

will increase. But a strengthening project to help

your home resist earthquakes will not add to your

property taxes.

To receive the exclusion you must file a claim form

with your county assessor. The work must also be

approved as appropriate seismic strengthening by

your local building department.

A sample form from the County of Santa Clara is

attached on page 49. This form may vary by


The Homeowner’s Guide to Earthquake Safety 5

Earthquake Insurance

Earthquake insurance is typically not part of your

homeowner insurance policy. All insurance

companies that sell residential property insurance

in California are required by law to offer

earthquake insurance to homeowners when the

policy is first sold and every two years afterward.

The cost of the earthquake policy you are offered

is based on a number of factors, including your

home’s location, age, construction type, and value.

One thing to consider would be to compare the

expected damage versus the deductible that is

applicable to your policy. You may wish to consult

a licensed civil or structural engineer for more

specific information on your potential for damage.

Each homeowner should consider his/her

individual risk factors and then weigh the cost of

earthquake coverage against the benefits. The

California Earthquake Authority (CEA) website has

an online calculator to help estimate your premium

based on your ZIP Code, insured value, dwelling

type, and desired coverage and deductible.

The California Earthquake Authority is required to

provide, and the insurance companies are required

to disclose the availability of, discounts on

earthquake insurance premiums for older homes

that have been strengthened to resist earthquake

damage. For more information, contact your

insurance agent, who can also help you locate an

earthquake insurer and estimate your annual


California Earthquake Authority:

California Department of Insurance:


6 The Homeowner’s Guide to Earthquake Safety



Dane Golden, FEMA News Photo

Figure 5 - San Simeon Earthquake, Dec. 22, 2003

This home slid two feet off its foundation due to

inadequate nailing of walls to its sill plates.

Figure 4 - Northridge Earthquake, Jan. 17, 1994

Chimney Collapse - common type of damage to

unreinforced masonry.

FEMA News Photo

Figure 2 - Loma Prieta Earthquake, Oct. 17, 1989

Home moved off of its foundation and was considered

a total loss.

Robert A. Eplett, OES

Figure 3 - Northridge Earthquake, Jan. 17, 1994

Single family residence damaged due to failure of

multiple elements.


Figure 6 - San Simeon Earthquake, Dec. 22, 2003

The collapsed porch was not adequately attached to

this single family residence.

Guna Selvaduray

Figure 1 - San Fernando Earthquake, Feb. 9,

1971 Severely damaged split level 1 and 2 story

wood frame dwelling. The one story portion

dropped about 3 feet.

Pacific Fire Rating Bureau



The Homeowner’s Guide to Earthquake Safety 7


Source: California Geological Survey, 1986; Earthquake History of the U.S., U.S. Department of Commerce and Interior, 1982;

Records of California Office of Emergency Services; compiled and revised by California Seismic Safety Commission, 2004;

International Code Council, Uniform Building Code 1997 Edition.

EUREKA, 1954,




Figure 7—Earthquake history. California has

experienced many damaging earthquakes in the

past two centuries. The sizes of the dots on this

map indicate the relative magnitude of earthquakes

that occurred at these locations.

Seismic Zones in California. All of California

lies within Seismic Zone 3 or 4. There are four

zones in the U.S.A., ranging from 1 to 4; the

higher the number the higher the earthquake

danger. Stronger construction standards for

buildings in Zones 3 and 4 have been adopted in

the Uniform Building Code.


1940, 1979, 1987


BEAR, 1992

TAHOE, 1966






























8 The Homeowner’s Guide to Earthquake Safety


San Andreas Fault

Santa Barbara

Figure 8 - Earthquake Faults - Map showing

major earthquake faults in California on which

earthquakes are most likely to occur.

Map courtesy of California Geological Survey. Fault locations modified from seismic sources used in Revised 2002 California

Probabilistic Seismic Hazard Maps.


San Francisco

Los Angeles

San Diego

For a more detailed map, including

names of faults, go to:

The Homeowner’s Guide to Earthquake Safety 9

Figure 9 - Earthquake Shaking Potential Map - This

map shows the relative intensity of ground shaking and

damage in California from anticipated future


?? Expected damages in California in the

next 10 years exceed $30 billion.

?? Three-quarters of our nation’s

earthquake losses will be in California.

?? Efforts to reduce the losses from

earthquakes have already proven




Data source: California Seismic Safety Commission, California Geological Survey, Governor’s Office of Emergency

Services, and United States Geological Survey, April, 2003, Earthquake Shaking Potential for California, California

Seismic Safety Commission Publication No. 03-02.

Regions near major, active

faults. These will on average

experience stronger earthquake

shaking more frequently.

Regions distant from known,

active faults. These will

experience lower levels of

shaking less frequently.

Increasing intensity



San Francisco

San Jose


Los Angeles

Long Beach

San Diego

For a full color version go to:

Please note:

10 The Homeowner’s Guide to Earthquake Safety


There are many additional resources available. Some are web sites and some are

books or pamphlets.

?? The California Seismic Safety Commission has created a webpage that

provides links to other sites that are appropriate for homeowners

interested in improving the earthquake safety of their homes.


?? FEMA also provides a wide variety of information suitable for the

homeowner, including the availability of, and registration for, federal

disaster aid programs after a damaging earthquake or other disasters.


The earthquake weaknesses identified in this section, if not corrected, can result in

one or more of the following:

?? Injury to occupants

?? Severe damage to your home

?? Broken gas and utility lines

?? Fires from broken gas lines

?? Damage to floors, walls, and windows

?? Damage to the contents in the house

?? Damage to the foundations

Please remember that:

?? Retrofitting before an earthquake is relatively cheap.

?? Doing major structural repairs to your home after an earthquake is very


?? Sometimes the damage is extensive enough to require the entire house to

be demolished.

?? After an earthquake, there is usually a shortage of available licensed

contractors and engineers in the impacted area, because of the sudden

high demand for their services.

?? An appropriate seismic retrofit will reduce damage and save you money.

Please consult your local Building Department and/or a licensed architect or

engineer for more detailed information.

The Homeowner’s Guide to Earthquake Safety 11




The Problem

If water heaters are not properly braced, they can

topple over during an earthquake causing:

?? Broken gas lines and gas leaks

?? Fires causing major damage to homes

?? Broken water lines and flooding

How to Identify

?? Is the water heater free-standing?

?? Are there straps or other types of restraints

securing the water heater?

?? Are there straps or restraints bolted to the


?? Are there flexible pipes for water and gas

connected to the water heater?


?? Replacing a water heater after an earthquake

can cost more than $500.

?? Repairing fire damage and flooding damage

can cost several thousand dollars, including the

entire cost of your home!

?? There are many different ways of strapping a

water heater. One example is shown on the

next page. (See page 13)

?? Check with your local Building Department for

details of local requirements.

?? Know where your main water valve is so that

you can shut it off if you have a water leak.

?? Know where your main gas valve is so that you

can shut it off if you hear or smell a gas leak.

(See page 32)

Contents Damage

Unbraced Water Heaters

12 The Homeowner’s Guide to Earthquake Safety

Figure 10 - The unbraced water heater in

this home fell during an earthquake; the

resulting fire destroyed the home.

Governor’s Office of Emergency Services

Water heater

Figure 11 - This unstrapped water heater

tipped over during the 1984 Morgan Hill

Earthquake. Fortunately gas and water

lines were not ruptured.

Guna Selvaduray

Comparison of Cost: Preventing vs. Repairing Earthquake Damage

Project Cost Cost to Repair after an Earthquake


Water heaters must be braced (securely attached) to the studs in a wall. California law requires water

heaters to be braced at the time of sale, or when a new water heater is installed.

How-to Resources

?? Your local home improvement store

?? How to Brace Your Water Heater, City of Los

Angeles, Department of Building & Safety,

Information Bulletin #P/PC 2002-003, June 14,


?? Guidelines for Earthquake Bracing of Residential

Water Heaters, Department of General Services,

Division of State Architect, August 11, 2004.

?? How to Secure Your Water Heater, Governor’s

Office of Emergency Services, 2003.

The Solution

There are many solutions – all relatively


?? Purchase and install a strap kit or

bracing kit from your local hardware

store. Be sure the kit is certified by

the State Architect.

Other options include:

?? Have a licensed plumber strap your

water heater according to code.

?? Use metal tubing or heavy metal

strapping and lag screws and

washers to secure the water heater

to the wall studs.

The gas and water lines should also have

flexible pipes. These are safer than rigid

pipes during an earthquake.

Be sure to check the straps once a year.

They may come loose due to vibrations,

or other causes.

$20 to $200 $500 to total value of home (if completely destroyed).

The Homeowner’s Guide to Earthquake Safety 13

Brace Water Heaters

Figure 12: One Method of Water Heater Bracing. Straps

and screws visible with water heater in a garage installation.

You may need to add wood blocking.


If wood blocking is used, it

must be attached to studs.








The Problem

Houses that are not bolted to the foundation can

move off their foundations during earthquakes.

How to Identify

?? Go down into the crawl space – the area

between the first floor and the foundation – to

find out if your house is bolted to its foundation.

?? Look for the heads of anchor bolts that fasten

the sill plate – the wooden board that sits

directly on top of the foundation – securely to

the foundation. (See Figure 14a, page 15)

?? You should be able to see the large nuts,

washers, and anchor bolts, installed at least

every 4 to 6 feet along the sill plate. Steel

plates are sometimes used instead of anchor

bolts. (See Figure 14b, page 15)


?? It is very expensive to lift a house, and place it

back on its foundation.

?? Homes moving off their foundations can cause

gas lines to rupture, which in turn can result in


Home Not Anchored to Foundation

14 The Homeowner’s Guide to Earthquake Safety

Slab Foundations

Some homes are built directly on concrete slabs. These houses do not have crawl spaces

and cripple walls.

Nearly all homes with slab foundations that were originally built to code will have anchor

bolts or straps.

However, if the house is not bolted to the slab, you have an earthquake weakness.

Newer homes generally have anchor bolts or straps.

If you have an unfinished garage, you may be able to see the anchor bolts.

You are not required to remove siding, drywall or plaster to determine if your house has

anchor bolts.

If your home has no foundation, or an old

concrete foundation, see page 30.

Figure 13 - This home wasn’t bolted and slid off its

foundation. Sometimes the damage can be so bad that

houses have to be demolished.

Office of Emergency Services

Comparison of Cost: Preventing vs. Repairing Earthquake Damage

Project Cost Cost to Repair after an Earthquake


Figure 14 Anchor bolts or steel plates. A home’s crawl

space may be formed by a cripple wall (see next page for

description) between the foundation and the floor joists or the

floor joists may rest directly on the sill plate. In either case,

you should be able to see the heads of anchor bolts or steel

plates installed at appropriate intervals. These fixtures fasten

the sill plate to the foundation.

The Solution

Drill holes through the sill plate into the foundation

and install anchor bolts. (See Figure 14a)

If there is not enough room to drill, you can attach

steel plates to hold the sill plate to the foundation.

(See Figure 14b)

Anchor bolts have to be installed properly for them to

be effective.

You must obtain the proper permits from your local

Building Department before beginning work.

SNCCCCtoooronnnuntttscteeeHttennnrunOutttrtssscaWs tlDDD u-DDTaaaraaaOmmmmlm aaaHaagggaggeeezeeards

How-to Resources

?? Detailed information for do-it-yourselfers or

engineers can be found in the International Existing

Building Code, published by the International Code


?? Publication: How You Can Strengthen Your Home

for the Next Big Earthquake in the Los Angeles

Area, City of Los Angeles, Department of Building

& Safety, October 2001.

Anchor Foundation

The Homeowner’s Guide to Earthquake Safety 15

$250 to $5,000 $25,000 to total value of home (if completely destroyed).

Figure 14b



Steel plates

Floor joists

Wall stud





Sill Plate

Tops of

anchor bolts



Wall studs

Floor joists

Figure 14a





The Problem

Wooden floors and stud walls are sometimes built

on top of an exterior foundation to support a house

and create a crawl space. (See Figure 17, page 17)

These are called cripple walls and they carry the

weight of the house.

During an earthquake, these walls can collapse if

they are not braced to resist horizontal movement.

If the cripple wall fails, the house may shift or fall.

How to Identify

?? Go under the house through the crawl space, to

see if there are any cripple walls.

?? If there are cripple walls, check to see if they

are braced.

?? There should be plywood panels adequately

nailed to the studs OR there should be diagonal

wood sheathing. (See Figure 16)

?? If you have neither of these, the cripple walls

are probably insufficiently braced or unbraced.

?? Horizontal or vertical wood siding is not

strong enough to brace cripple walls.


?? It is very expensive to lift a house, repair

the cripple wall, and put it back on its


SNCtoornnutscettnruutrsca tlD uDaraamlm aHagagezeards

Weak Cripple Walls

Figure 15 - Damage to home due to cripple

wall failure.

16 The Homeowner’s Guide to Earthquake Safety

Figure 16 - Diagonal Sheathing. Common in older homes.

Office of Emergency Services



First floor

Cripple wall



Comparison of Cost: Preventing vs. Repairing Earthquake Damage

Project Cost Cost to Repair after an Earthquake


The Solution

Plywood, or other wood products allowed by code,

should be nailed to the studs.

The following are important:

?? Type of wood product used

?? Plywood thickness

?? Nail size and spacing

?? Do not cover vents.

Consult your local Building Department for permit

requirements before starting work.

Strengthen Cripple Walls

The Homeowner’s Guide to Earthquake Safety 17

$500 to $2,500 $25,000 to total value of home (if completely destroyed).

First floor



Floor joists Plywood panels

Nails at



Anchor bolts at

appropriate intervals


Vent holes




How-to Resources

?? Detailed information for do-it-yourselfers or

engineers can be found in the International

Existing Building Code, published by the

International Code Council

?? Publication: How You Can Strengthen Your

Home for the Next Big Earthquake in the Los

Angeles Area, City of Los Angeles,

Department of Building & Safety, October


2x4 Stud


top plate




Sill plate


Nails at



Figure 17—Plywood or

diagonal sheathing

strengthens weak cripple

walls. If your home has a

cripple wall between the

foundation and the first

floor, and the wall is not

braced with plywood or

diagonal sheathing, the

house may fall or shift off

its foundation during an




The Problem

The outside of the house is supported by wood

posts resting on unconnected concrete piers.

Siding is often nailed to the outside of the posts,

making them not easily visible.

During an earthquake these posts can fail, if they

are not braced against swaying.

If the posts fail, the house may shift or fall.

How to Identify

?? Go under the house to see if there is a

continuous foundation under the outside walls.

?? If you do not see a continuous foundation you

may have an earthquake weakness.

??If you see only unconnected concrete piers and

wood posts, or only wood posts, supporting the

outside walls, you have an earthquake



?? Horizontal or vertical wood siding is not strong

enough to brace pier-and-post foundations.

?? Major structural repairs, like lifting an entire

house to repair the posts and putting it back,

are very expensive.

Pier-and-Post Foundations

18 The Homeowner’s Guide to Earthquake Safety

California Seismic Safety Commission

Figure 18 - The pier-and-post

foundation under this home shifted

during a recent earthquake.

California Seismic Safety Commission

Comparison of Cost: Preventing vs. Repairing Earthquake Damage

Project Cost Cost to Repair after an Earthquake


The Solution

Consult a licensed architect or engineer, and a

licensed building contractor who specializes in

foundations, to fix this problem.

It may be possible to make the foundation safer by

bracing the posts.

You might be better off to add a new foundation and

plywood walls in the crawl space to make sure that

the house will not shift or fall off its foundation

during an earthquake.

How-to Resource

?? Detailed information for engineers can be found in

the International Existing Building Code, published

by the International Code Council.

NCCoonnttseetnnruttssc tDDuaaramml aaHggaeezards

Strengthen Pier-and-Post Foundations

The Homeowner’s Guide to Earthquake Safety 19

$1,000 to $25,000 $20,000 to total value of home (if completely destroyed).



The Problem

Unreinforced masonry—brick, concrete block, or

stone—foundations often cannot resist earthquake

shaking. They may break apart, or be too weak to

hold anchor bolts. Homes may shift off such

foundations during earthquakes, damaging the

walls, floors, utility lines, and home contents.

How to Identify

?? If your home’s foundation is brick or stone, and

looks like one of the foundations shown in the

photos here, it is probably unreinforced.

?? If there is a space filled with grout between the

inner and outer faces of a brick foundation

(where anchor bolts and reinforcing steel could

be installed), it may be reinforced.

?? If the outside of the foundation is covered, you

may have to look under the house to see the

type of foundation you have.

?? If you are not sure what to look for, seek the

services of a licensed engineer to determine if

your foundation is reinforced or not.


?? It is cheaper to do this before an earthquake

damages the house than after.

Figure 20 - Note the bricks exposed in this unreinforced

masonry foundation.

Figure 19 - This is an unreinforced stone foundation.

They typically fail during earthquakes.

Unreinforced Masonry Foundations

20 The Homeowner’s Guide to Earthquake Safety

California Seismic Safety Commission California Seismic Safety Commission

Comparison of Cost: Preventing vs. Repairing Earthquake Damage

Project Cost Cost to Repair after an Earthquake


The Solution

There are several ways to fix this problem.

The most common approach is to replace all or

part of the existing foundation with a poured

reinforced concrete foundation.

Another solution is strengthening the unreinforced

brick or stone foundation, which is generally


Seek the help of a licensed architect or engineer,

and a licensed foundation contractor or general


How-to Resource

?? Detailed information for engineers can be found in

the International Existing Building Code, published

by the International Code Council.

SSNCCCCttooorrounnnuunctttsccteeeHtttteunnnruunOurtttrrtsssacaaWs ltllDDD u-DDDTaaaraaaaOmmmmmlm aaaHaaagggagggeeezeeeards

Retrofit Masonry Foundations

The Homeowner’s Guide to Earthquake Safety 21

$15,000 to $50,000 $15,000 to total value of home (if completely destroyed).



The Problem

Houses built on the sides of steep hills are often

set on exposed posts or columns, as shown in the


The potentially hazardous conditions that are

unique to homes on steep hillsides are:

?? Stilt-type posts with or without diagonal


?? Walls with very different heights or that are

stepped or sloped down the hillsides.

If these posts or walls are not properly braced,

they may collapse during an earthquake.

Sometimes, the supports on the downhill side will

be hidden behind a tall wall that encloses a large

unfinished space. (This is similar to, but taller

than, a crawl space under a typical house built on

flat ground.)

How to Identify

?? Is the house located on a slope?

?? Are the columns or walls supporting the home


?? If you are not sure if there is bracing or if the

bracing is adequate, consult a licensed



?? It is very expensive to lift a house, repair the

posts, and put it back.

Homes Built on Steep Hillsides

22 The Homeowner’s Guide to Earthquake Safety

Figure 22 - This hillside home was built on an

unbraced tall wall that failed.

Figure 23 - This photograph shows an interior detail of a

home similar to the one above, showing substantial damage

to a building with an unbraced tall wall.

Office of Emergency Services

Office of Emergency Services

Comparison of Cost: Preventing vs. Repairing Earthquake Damage

Project Cost Cost to Repair after an Earthquake


The Solution

Consult a licensed architect or engineer, and a

licensed contractor, to fix this problem.

How-to Resources

?? Detailed information can be found in the

International Existing Building Code, published by

the International Code Council.

?? Voluntary Earthquake Hazard Reduction in Existing

Hillside Buildings, City of Los Angeles Municipal

Code, Chapter IX, Article 1, Division 94.

Strengthen Homes on Steep Hillside

Figure 24 - Hillside homes with sloped and tall walls or posts

require special engineering.

The Homeowner’s Guide to Earthquake Safety 23

$1,000 to $50,000 $10,000 to total value of home (if completely destroyed).

PEER and Nels Roselund, SE Sloped or


wall Tall




The Problem

Houses built of unreinforced masonry – bricks,

hollow clay tiles, stone, concrete blocks, or adobe

– are very likely to be damaged during


The mortar holding the masonry together is

generally not strong enough to resist earthquake


Anchorage of walls to the floor and the roof is


These houses are weak (brittle) and can break


Walls may fall away or buckle, resulting in


How to Identify

?? Can bricks or stone be seen from the outside

(unless the walls are covered with stucco)?

?? Do the brick walls have “header courses” of

bricks turned endways every five or six rows?

(See Figure 26)

?? Was the house built before 1940?

If you cannot tell from the outside, turn off the

power and take the cover plate off one of the

electrical outlet boxes on an outside wall and look

for brick or other masonry.

If the wall is concrete or concrete block, it is very

difficult to find out if reinforcing steel was added

during construction.

You will then need:

?? The house’s plans, which may be on file with

the Building Department, or

Unreinforced Masonry Walls

24 The Homeowner’s Guide to Earthquake Safety

Figure 26 - Header courses

of bricks are usually placed

endwise every six or so rows

in unreinforced masonry

walls to tie the outer layer of

bricks to the layers inside the


?? To consult a licensed engineer to make

the determination.


?? It is very expensive to shore up a house,

remove damaged walls, and put in new


California Seismic Safety Commission

Figure 25 - The plaster-covered brick walls of this

building collapsed during a recent earthquake.

California Seismic Safety Commission

Comparison of Cost: Preventing vs. Repairing Earthquake Damage

Project Cost Cost to Repair after an Earthquake


The Solution

Consult a licensed architect or engineer to fix this


One solution may involve:

?? Tying the walls to the floor and roof

?? Installing a steel frame and bolting the

wall to it.

How-to Resource

?? Detailed information can be found in the International

Existing Building Code, published by the

International Code Council.

Strengthen Unreinforced Masonry Walls

The Homeowner’s Guide to Earthquake Safety 25

Project and Repair costs can vary widely.

Figure 27 - Unreinforced masonry wall strengthened by

installing a steel frame inside.

Jessica Tran

Figure 28 - Bolting of unreinforced masonry wall to steel

frame on the inside.

Jessica Tran







The Problem

The large opening of a garage door and the weight

of a second-story room built over the garage can

result in the walls being too weak to withstand

earthquake shaking.

When the narrow sections of the wall on each side

of the opening are not reinforced or braced, the

weakness is worse.

How to Identify

?? Is the garage door opening in line with the rest of

the house? (See Figure 30)

?? If this is the case, additional bracing may not

be needed.

?? Is the house shaped like Figure 31? If this is the

case, are there braces or plywood panels around

the garage door opening?

?? If there are no braces or plywood panels,

strengthening may be needed.

?? Consult a licensed architect or engineer to

determine the strengthening required.


?? Many homes with this weakness have been

severely damaged in past earthquakes.

Rooms over Garages

26 The Homeowner’s Guide to Earthquake Safety


Figure 30 - If the wall of the main house is in line

with the wall containing the door of a garage with a

room over it, the adjoining wall may help brace the


Garage House

Figure 31—Additional bracing. Home configuration

where there is no in-line wall. Additional bracing may

be appropriate in this situation.


with room



Figure 29 - This mountain home was built over a garage, and

its walls were not strong enough to withstand an earthquake.

Office of Emergency Services

Wall may need bracing

Comparison of Cost: Preventing vs. Repairing Earthquake Damage

Project Cost Cost to Repair after an Earthquake


The Solution

Consult a licensed architect or engineer to design

plywood paneling or a steel frame around the door

opening (See Figure 32).

Have plans drawn.

Obtain a permit from your local Building


Strengthen Rooms over Garages

Figure 32—Bracing garage walls. If your house has a

room over the garage, the garage walls may not be strong

enough to hold up during an earthquake unless they are

braced with plywood panels and steel straps.

The Homeowner’s Guide to Earthquake Safety 27

$5,000 to $25,000 $15,000 to total value of home (if completely destroyed).

How-to Resource

?? Detailed information can be found in the International

Existing Building Code, published by the

International Code Council.



Steel straps

Anchor Bolts and Tie Downs

The Problem

Many chimneys are built of unreinforced brick or

stone. During an earthquake these can collapse

or break and fall on the roof.

When the chimney fails, the falling stones and

bricks can:

?? Cause injuries

?? Damage the house

?? Damage cars

Tall slender chimneys are most vulnerable.

How to Identify

?? Check the mortar between the bricks or stones

with a screwdriver. If it crumbles when you pick

at it, the chimney may be a hazard.

?? Inspect the attic and floor spaces for metal ties

that should be holding the chimney to the


?? Determining whether a chimney is susceptible

to earthquake damage is not always easy.

When in doubt, consult a licensed engineer or



?? Do not locate patios, children’s play areas, or

parking spaces near a questionable chimney.

?? Tell family members to get away from

chimneys and fireplaces during earthquakes.

28 The Homeowner’s Guide to Earthquake Safety



OTHER Unreinforced Masonry Chimneys


Figure 33 - This unreinforced chimney fell during a recent


Office of Emergency Services

Figure 34 - Morgan Hill Earthquake. Broken chimney fell on


Guna Selvaduray

The Solution

Tear down the old or damaged chimney and

replace with a newly constructed chimney.

Several steps can be taken to reduce the risk of

damage from falling chimneys, depending upon

the type of chimney you have. They include:

?? Add plywood panels at the roof or above the

ceiling joists to prevent the brick or stone from

falling into the house.

?? This can be done by layering plywood

above the ceiling, in the house’s attic, or

nailing plywood under the shingles when


?? Replace the upper chimney with metal flues.

?? Strengthen the existing chimney.

?? This can be a complicated process,

depending upon the construction and

height of the existing chimney.

Consult your local Building Department and obtain

necessary permits first.

How-to Resource

?? Reconstruction and Replacement of Earthquake

Damaged Masonry Chimneys, City of Los Angeles,

Department of Building & Safety, Information

Bulletin #P/BC-2002-70.

The Homeowner’s Guide to Earthquake Safety 29

Figure 35 - Photo showing damaged chimney removed.

Note that the fireplace is now not functional.

California Seismic Safety Commission

Strengthen Masonry Chimneys OTHER


$2,000 to $12,000 $15,000 to total value of home (if completely destroyed).

Comparison of Cost: Preventing vs. Reparing Earthquake Damage

Project Cost Cost to Repair after an Earthquake



No Foundation

The Problem Some older houses were built on wood beams laid directly on the ground,

without foundations. These houses may shift during earthquakes, causing

structural damage and breaking utility lines.

How to Identify Look under the house. If you see no concrete or masonry around the outside

walls, the house may lack a foundation.

What Can Be Done You may need to add a foundation to make the house earthquake resistant.

Just as when strengthening or replacing an unreinforced masonry foundation,

you will require the advice of a licensed architect, engineer, or foundation


Old Concrete Foundation

The Problem Some older concrete foundations were made with sand or stone that interacted

chemically over time, and the concrete eventually crumbles and becomes too

soft to withstand earthquake forces.

How to Identify Inspect the foundation for large cracks in the concrete, concrete crumbling off

the foundation, or concrete crumbling when you pick at it with a screwdriver.

What Can Be Done You may need to replace some or all of the foundation. You should consult a

licensed foundation contractor or an engineer.


30 The Homeowner’s Guide to Earthquake Safety



The Problem The design and construction features of some homes make them vulnerable to

earthquake damage, especially if these homes are not specifically designed and

built to resist earthquakes. Homes at risk are those with irregular shapes, large

windows (which can break in earthquakes and scatter shards of glass), more than

two stories, irregular walls, or porches and overhangs.

How to Identify Many homes with these features are strong enough to withstand earthquakes and it

is difficult to tell whether such homes need strengthening. If you have doubts about

one or more of these features in your home, or in a home you are planning to buy,

you should consult a licensed architect or engineer for an assessment.

What Can Be Done A professional can advise you on how to identify and fix earthquake weaknesses if

necessary. For example, large windows can be made safer by applying plastic film

on them.

The Homeowner’s Guide to Earthquake Safety 31

Homes with Unique Designs

The Problem

Natural gas piping and appliances can be damaged

during earthquakes, causing gas leaks.

If ignited, this can result in fires which can burn part

of, or, the entire house.

About one in four fires after an earthquake is related

to natural gas leaks.

Gas leaks after an earthquake are more likely if:

?? There are structural weaknesses

?? Gas appliances are not anchored

?? Flexible pipe connections are not used.

The primary concern is property loss from fire


The potential for life loss is limited since most single

family homes have several safe exits.

How to Identify

?? Examine all natural gas appliances (water

heaters, dryers, stoves, ovens, furnaces) to see

if they are anchored to the floor or walls, and

have flexible pipe connections.

Plan Ahead

Locate your gas meter outside your home.

Identify the exact location of the shutoff valve and

make sure that you have access to it.

Make sure you have a wrench that is readily

available to turn off the gas when needed.

32 The Homeowner’s Guide to Earthquake Safety


Figure 36—Manual Shutoff Valve Location

Close-up view of Valve

Manual Gas Shutoff

?? The most cost-effective way to manage the

risk from natural gas is to know how and when

to manually shut off the gas.

?? Use the wrench to turn off the manual valve

located at the gas meter (See Figure 36, page


?? Shut off your gas only if you:

?? Smell gas

?? Hear gas escaping

?? Suspect a broken gas pipe, appliance,

vent, or flue.


?? Once the gas has been shutoff, service can

be restored only by utility personnel or

qualified plumbers.

?? High demands for qualified personnel after an

earthquake can lead to substantial delays in

restoring natural gas service.

The Homeowner’s Guide to Earthquake Safety 33


?? Seismic Gas Shut-Off Valve Requirements in Los

Angeles, City of Los Angeles, Department of

Building & Safety, Information Bulletin #P/PC 2002-

001, April 30, 2003.

?? Improving Natural Gas Safety in Earthquakes,

California Seismic Safety Commission, Publication

#CSSC-02-03, July 2002.

?? Gas Shutoff Valve Certification Program, Division

of the State Architect.

Automatic Gas Shutoff Options

There are a variety of automatic gas shut-off valves

available. These cost more than manual shutoff

valves and may provide additional safety but may

also have some disadvantages.

The types of valves available include:

?? Earthquake shake-actuated valves

?? Excess flow valves

?? Methane detectors

?? Hybrid systems

?? Others.

These can be installed on the “customer owned”

side of the gas meter.

Consult your local Building Department because:

?? Some installations will require building permits.

?? Some local jurisdictions have adopted

ordinances requiring automatic gas shutoff

devices at the time of sale or during significant


?? Decide which strengthening project or projects

you are going to do.

?? Get the necessary building permits first.

?? If you are “doing-it-yourself,” you still need

the proper permits.

?? For more complex projects, have a licensed

architect or engineer draw up the necessary

plans and specifications.

?? Interview two or three architects or


?? Ask for references or former clients.

?? Talk to references or former clients.

?? Compare experience, ideas, and fees.

?? Submit the plans for approval to your local

building department.

?? Remember: the building codes are

designed for your safety.

There are many publications that describe

strengthening projects in detail.

Visit the California Seismic Safety Commission’s

website at, which provides

many useful links.

?? Get the documents that relate to your project

and read them.

?? This will help you to better understand what

the architect or engineer is doing, and also

what the contractor is doing.

?? The International Existing Building Code

Appendix Chapter 3 contains the best current

guidelines. Ask your local Building Department

to review a copy.

?? Select your licensed contractor.

?? First make sure the contractor is properly


?? Interview at least two or three contractors.

?? Ask your licensed architect or engineer for


?? Ask for references or former clients.

?? Talk to references or former clients.

?? Compare experience, fees, and terms of


?? Get at least three written bids for the

construction work.

?? The lowest bid may not be the best bid.

?? Keep all plans, permits, and other records of

your strengthening project.

?? Provide future buyers of your home with


If your home has been designated as “historical,”

you also may need to comply with the California

Historical Building Code.

?? Contact your local Building Department for

further help with this.


Whether you do it yourself, or hire a contractor,

you need permits from your local Building


It costs far less to correct earthquake weaknesses

before an earthquake than to repair the damage

after an earthquake.

If your home is damaged in an earthquake, you will

probably also have other costs such as lodging,

medical, etc.



34 The Homeowner’s Guide to Earthquake Safety




The contents of this section have been adapted from “After a Disaster, Don’t Get Scammed” by the

Contractors State License Board.

After a Disaster...


?? Rush into repairs, no matter how badly they

are needed.

?? Hire the first contractor who comes along.

?? Accept verbal promises.


?? Get proof that the person you are dealing with

is a California licensed contractor appropriate

for the work to be done.

?? Get the contractor’s license number and verify

that it is current and valid.

?? Get a written contract that contains all the

details of the job to be performed.

?? Get at least three bids.

?? Check references of other work the contractor

has done, if possible, in your area.

?? Develop a payment schedule with the


?? Consider a completion bond on large projects.

Avoid Payment Pitfalls

?? By law, a down payment on a home

improvement contract cannot exceed:

?? 10% of the contract price, or

?? $1000

whichever is less!

?? Withhold at least 10% of the total

contract price until the project is


?? Do not make final payment until:

?? The building department has signed

off on it,

?? You are satisfied with the job, and

?? You take a final walk-through to

make sure work is complete and

done correctly.

Useful publications from the Contractor’s State

License Board (

?? What You Should Know Before You Hire

a Contractor - Provides information about

hiring and working with contractors.

?? Home Improvement Contracts: Putting

the Pieces Together - Provides answers

about the legal requirements of home

improvement contractors.

The Homeowner’s Guide to Earthquake Safety 35

Contractors must be licensed for any

job which costs $500 or more, including

materials and labor.


Sellers of real estate in California are required to

disclose to buyers certain information regarding

natural hazards that can affect the property being

sold. In addition to flood and fire hazard

information, disclosure of seismic hazards is also


Earthquakes are common in California because of

the many earthquake faults located throughout the


This section:

?? Describes briefly the basic geology-related

hazards, and

?? Introduces the government mapping programs

that define which areas are susceptible

to those hazards.

Ground Shaking:

?? Ground shaking causes 99% of the earthquake

damage to California homes.

?? Areas near large active faults are more likely

to be shaken severely than areas in the rest

of the state.


?? Earthquakes can also trigger landslides.

?? Earthquake shaking can cause the soil and

rock to slide off a slope, ripping apart homes

on the slope and/or crushing homes downhill

(See Figure 37).

Fault Rupture:

?? An actual crack forms and the ground is

offset along the two sides of a fault during an

earthquake (See Figure 38).

?? A house built over an active fault can be torn

apart if the ground ruptures beneath it.

?? If the house is built over a “creeping” fault –

one that moves slowly with no earthquakes or

a series of very small earthquakes – the

damage may not be noticed for some time.

36 The Homeowner’s Guide to Earthquake Safety

Patrica Grossi and Augustin Rodriguez, EERI

Figure 37 - Landslide. San Simeon Earthquake, December

22, 2003 Landslides on San Gregorio Road in Atascadero,

California, only a short distance away from where the homes

with the most damage were located.

Robert A. Eplett, OES, CA

Figure 38 - Fault Rupture. Landers Earthquake of June 28,

1992, produced a surface rupture of over 50 miles along faults

in the Mojave Desert.

Lateral Spreading:

?? Intense shaking during an earthquake can

cause the soil to break into blocks which move

apart from each other. This can cause

damage to the foundation of a house (See

Figure 39).


?? During earthquakes, loose, wet sandy soil

can become almost like quicksand, and lose

its ability to support structures. This can

cause the foundation of a house to sink,

break, or tilt (See Figure 40).


?? A tsunami is a series of large sea waves

caused by an underwater earthquake or


?? Coastal areas are prone to tsunami damage.

?? Tsunami waves can come from a great

distance and can cause flooding or wash

away houses in low-lying areas along the


Dam Failure:

?? Earthquake damage to a dam can cause

sudden and devastating flooding of houses


?? During the 1971 San Fernando Earthquake,

the Lower San Fernando Dam above the San

Fernando Valley was damaged. Had it failed,

it would have flooded the homes below,

causing many deaths and injuries. (See

Figure 41). Risk of an aftershock forced

residents in an 11-square mile area to

evacuate for the next 3 days.

?? California has some of the world’s best

standards for building and inspecting dams.


If you live in a low-lying coastal area or a dam

inundation zone, become familiar with evacuation

routes to higher ground and be prepared

to evacuate such areas immediately

after an earthquake.

The Homeowner’s Guide to Earthquake Safety 37

Figure 39 - Lateral Spreading. Loma Prieta Earthquake,

October 17, 1989. Lateral spreading damage levee road

along the San Lorenzo River.

NISEE Clearinghouse Project

Figure 40 - Loma Prieta Earthquake, October 17, 1989.

Lateral spreading, liquefaction and sand boils caused

extensive damage in the Marina District of San Francisco,

about 60 miles away from the epicenter.

Walt Hayes

Figure 41 - Lower San Fernando Dam that was badly

damaged by the 1971 San Fernando Earthquake.

Robert A. Page, David M. Boore and Robert F.

Yerkes, USGS

Earthquake Hazard Mapping

Enormous progress has been made in

understanding how, why, and where earthquakes

occur. This has led to the creation of maps that

highlight areas having the highest likelihood of

damaging earthquakes.

Five mapping programs have been developed to

help Californians lead safer lives in earthquake


National Seismic Zones

The U.S. is divided into four major zones, each

having a different likelihood of strong ground

shaking. The earthquake hazard potential for the

U.S., determined through a national program, has

been generalized into four seismic zones,

numbered Zone 1 through Zone 4. Zone 1 has the

lowest earthquake danger and Zone 4 has the

highest earthquake danger. Most of the densely

populated parts of California are in Zone 4.

(See Figure 7, page 7)

The National Seismic Zone map is published by

the International Code Council (ICC) in the

California Building Code.

Earthquake Fault Zone Maps

These maps are also known as the Alquist-Priolo

Earthquake Fault Zone Maps, named after the

California legislators who initiated the legislation

that mandated these maps. The maps show

active earthquake faults prone to surface ruptures

and identify a 1,000 ft. wide zone with the fault line

at the center.

Seismic Hazard Zone Maps

These maps show areas where landslides and

liquefaction are most likely to occur during


Tsunami Inundation and Evacuation Route Maps

Maps for the Pacific Coast show areas where lowlying

regions are exposed to tsunami inundation.

These maps are in various stages of preparation and


Dam Inundation Maps

These maps show the areas below major dams that

may be flooded in the event of their failure.

How are these Maps Used?

The zones defined by the maps are at greatest

potential risk when a major earthquake occurs. This

is particularly the case when the earthquake occurs

during or shortly after a heavy rainfall, which increases

the likelihood of liquefaction and landslides.

California law requires that the information from the

Earthquake Fault Zone and Seismic Hazard Zone

maps be incorporated into local general plans, and

any land-use planning or permitting ordinances.

Cities and counties must establish regulations

governing development within these zones.

Special geotechnical studies are required before

buildings can be built in Earthquake Fault Zones or

Seismic Hazard Zones.

Your local building or planning department can show

you the National Seismic Zone Map as well as the

other maps if they are available for your community.

These maps, if they are available, may be accessed


38 The Homeowner’s Guide to Earthquake Safety

The Seller of real estate within a hazard zone must disclose that the property lies

within such a zone at the time of sale.

The Homeowner’s Guide to Earthquake Safety 39


HOLD ON.” Get under a sturdy desk or table and hang on to it, or

move into a hallway or get against an inside wall. Stay clear of

windows, fireplaces, and heavy furniture or appliances. Get out of

the kitchen, which is a dangerous place in earthquakes since it’s full

of things that can fall on you. Don’t run downstairs or rush outside

while the building is shaking or while there is danger of falling and

hurting yourself or being hit by falling glass or debris.

2. IF YOU ARE OUTSIDEGET INTO THE OPEN, away from buildings,

power lines, chimneys, and anything else that might fall on you.

3. IF YOU ARE DRIVINGSTOP, but carefully. Move your car as far

out of traffic as possible. Do not stop on or under a bridge or overpass

or under trees, light posts, power lines, or signs. Stay inside

your car until the shaking stops. When you resume driving, watch for

breaks in the pavement, fallen rocks, and bumps in the road.


FOR LANDSLIDES, falling rock, trees, and other debris that could

be loosened by earthquakes.

If You Feel a Strong Earthquake or Receive a

Tsunami Warning When You are on the Coast

1. DROP, COVER AND HOLD ON. Watch for falling objects until the

earthquake is over.

2. MOVE TO HIGHER GROUND or inland away from the coast immediately.

A tsunami may be coming. Go on foot if possible. The first

waves may reach the coast within minutes after the ground shaking

stops. The first wave is almost never the largest. Later waves may

be spaced tens of minutes apart and can continue arriving for many



WARNING. If you do not hear an evacuation announcement but

notice a sudden drop or rise in water level or hear a loud noise

coming from the water, nature may be warning you of impending


4. STAY AWAY FROM THE COAST. Do not return to the shore after

the first wave. Waves may continue to arrive for hours.

5. LISTEN TO A RADIO FOR AN “ALL CLEAR” before returning to the







Be sure you have these basic supplies on hand:

?? Fire extinguisher

?? Adequate supplies of medications that you or family members

are taking

?? Crescent and pipe wrenches to turn off gas and water supplies

?? First-aid kit and handbook

?? Flashlights with extra bulbs and fresh batteries

?? Portable battery-powered radio or television and extra fresh


?? Water for each family member for at least three days (allow at

least one gallon per person per day) and purification tablets or

chlorine bleach to purify drinking water from other sources

?? Canned and packaged foods, enough for three days, and at

least an additional four-day supply readily accessible for use if

you are confined to home. Don’t forget a mechanical can opener

and extra pet food!

?? Camp stove or barbecue to cook on outdoors (store fuel out of

the reach of children)

?? Waterproof, heavy-duty plastic bags for waste disposal

?? Copies of personal identification, such as driver’s licenses,

passports, and work identification badges, and copies of medical

prescriptions and credit cards

?? An extra set of car keys and house keys

?? Matches in waterproof container

?? Map of the area marked with places you could go and their

telephone numbers

?? Cash and coins

?? Special items, such as denture needs, contact lenses and

supplies, extra eyeglasses, and hearing aid batteries

?? Items for seniors, disabled persons, or anyone with serious


?? Items for infants, such as formula, diapers, bottles, pacifiers,

powdered milk, and medications not requiring refrigeration

What to Do Before, During, and After an Earthquake

The information contained in this section does not represent weaknesses in the earthquake resistance of

homes. It is valuable information to keep in mind to reduce risks to yourself, your family, and your home.

These lists are only highlights of the actions you should take.

Gather Emergency




40 The Homeowner’s Guide to Earthquake Safety

Plan Ahead

1. Create a family disaster plan; practice and maintain the plan.

2. Make and complete a checklist.

3. Plan home escape routes.

4. Conduct fire and emergency evacuation drills at least twice a

year and include your pets in your evacuation and sheltering


5. Test your smoke alarms once a month (daylight savings time or

birthdays) and replace batteries at least once a year in batterypowered

smoke alarms.

6. Make sure each member of your family knows what to do no

matter where they are when earthquakes occur.

?? Establish two meeting places where you can all reunite afterward:

one right outside your home, in case of a sudden

emergency, and one outside your neighborhood in case you

cannot return home or are asked to leave your neighborhood.

?? Find out about the earthquake plan developed by your

children’s school or day care.

?? Remember that since transportation may be disrupted, you

may have to stay at your workplace for a day or twofollowing

a major earthquake. Keep some emergency supplies—food,

liquids, and comfortable shoes, for example—at work.

?? Pick two out-of-town contacts:

?? A friend or relative who will be your household’s primary


?? A friend or relative who will be your household’s

alternative contact.

7. Know where your gas, electric, and water main shutoffs are and

how to turn them off if there is a leak or electrical short; if in

doubt, ask your utility companies. Make sure that all the older

members of your family can shut off the utilities.

8. Locate your nearest fire and police stations and emergency

medical facility. Remember that telephones may not work after

an earthquake. If you can, use your land line rather than your

cell phone to call 911, but only if you need emergency help.

9. Talk to your neighbors—how could they help you, or you help

them, after an earthquake?

10. Take a Red Cross first aid and cardiopulmonary resuscitation

(CPR) training course.

11. Make arrangements with friends or relatives to temporarily house

your pets after disasters because emergency shelters will not

accept pets.

12. If your home is located near a steep hillside, in an area near the

shore of a body of water or below a dam, check with your local

building or planning department to see if you are in a landslide,

tsunami or dam inundation zone. Plan for how, when, and where

your family should evacuate.

The Homeowner’s Guide to Earthquake Safety 41

42 The Homeowner’s Guide to Earthquake Safety

1. If a person is bleeding, put direct pressure on the wound. Use

clean gauze or cloth, if available.

2. If a person is not breathing, administer rescue breathing. The

front pages of many telephone books contain instructions on

how to do it along with detailed instructions on other first-aid


3. Do not attempt to move seriously injured persons unless they

are in immediate danger of further injury.

4. Cover injured persons with blankets to keep them warm.

5. Seek medical help for serious injuries.

1. Fire or fire hazards. Put out fires in your home or neighborhood

immediately. Call for help, but don’t wait for the fire department.

2. Gas leaks. Shut off the main gas valve only if you suspect a

leak because of broken pipes or the odor of natural gas. Don’t

turn it back on yourself—wait for the gas company to check for


3. Damaged electrical wiring. Shut off power at the control box if

there is any damage to your house wiring.

4. Downed or damaged utility lines. Do not touch downed power

lines or any objects in contact with them.

5. Spills. Clean up any spilled medicines, drugs, or other potentially

harmful materials such as bleach, lye, and gasoline or other

hazardous materials.

6. Downed or damaged chimneys. Approach chimneys with

caution. They may be weakened and could topple during

aftershocks. Don’t use a fireplace with a damaged chimney—it

could start a fire or let poisonous gases into your house.

7. Fallen items. Beware of items tumbling off shelves when you

open the doors of closets and cupboards.



Check for Injuries

Check for Hazards

Wear sturdy shoes to avoid injury from broken glass and debris.

Expect aftershocks.

The Homeowner’s Guide to Earthquake Safety 43

Note: The information in these

sections is reproduced in

whole or in part with the

permission of the copyright

owner, SBC. The Survival

Guide is available in the White

Pages of SBC Directories ©

SBC 2004. This information

was provided by medical and

emergency service authorities

and published as a public

service. While every

reasonable effort was made to

ensure its accuracy, SBC is not

responsible and assumes no

liability for any action

undertaken by any person in

utilizing such information. Any

person relying upon such

information does so at his or

her own risk.

?? Do not eat or drink anything from open containers near

shattered glass.

?? Do not turn the gas on again if you turned it off; let the gas

company do it.

?? Do not use matches, lighters, camp stoves or barbecues,

electrical equipment—including telephones—or appliances

until you are sure there are no gas leaks. They may create

sparks that could ignite leaking gas and cause an explosion

and fire.

?? Do not use your telephone, except for a medical or fire

emergency. You could tie up lines needed for emergency


If you need help and the phone doesn’t work, send someone

for help.

?? Do not expect firefighters, police, or paramedics to help you

right away. They may not be available.

Do Not . . .

1. If power is off, plan meals to use up foods that will spoil quickly, or

frozen foods. If you keep the door closed, food in your freezer

should be good for at least a couple of days.

2. Don’t light your kitchen stove if you suspect a gas leak.

3. Use barbecues or camp stoves, outdoors only, for emergency


4. If your water is off, you can drink supplies from water heaters,

melted ice cubes, or canned vegetables. Try to avoid drinking

water from swimming pools or, especially, spas—it may have too

many chemicals in it to be safe.

Check Your Food and

Water Supplies

Resource Organizations

Some of the organizations listed below have information to help you strengthen your home against earthquakes

and help you and your family prepare a personal earthquake response plan. Other resources that

can help you may be available in your community; check your local telephone directory.

Home Safety Information

Office of Emergency Services

Main Office

Information and Public Affairs

P.O. Box 419047

Rancho Cordova, CA 95741-9047

Telephone: (916) 845-8400

Regional Offices:

Coastal Region

1300 Clay Street, Suite 408

Oakland, CA 94612

Telephone: (510) 286-0895

Inland Region

P.O. Box 419047

Rancho Cordova, CA 95741-9047

Telephone: (916) 845-8470

Inland Region South

2550 Mariposa Mall, Room 181

Fresno, CA 93721

Telephone: (559) 445-5672

Southern Region

4671 Liberty Avenue

Los Alamitos, CA 90720

Telephone: (562) 795-2900

California Seismic Safety Commission

1755 Creekside Oaks Drive, Ste. 100

Sacramento, CA 95833

Telephone: (916) 263-5506

California Earthquake Authority

801 K Street, Suite 1000

Sacramento, CA 95814

Telephone: (877) 797-4300

Structural Safety Information

American Institute of Architects

Local chapters have referral lists of licensed

architects; consult telephone directory listing for

“American Institute of Architects.”

Structural Engineers Association of


1730 I Street, Suite 240,

Sacramento, CA 95814-3017

Telephone: (916) 447-1198

Local chapter organizations have referral list for

licensed structural engineers as follows:

San Diego -

Southern California -

Northern California -

Central California -

American Society of Home Inspectors

932 Lee Street, Suite 101

Des Plaines, IL 60016

Telephone: (800) 743-2744

Referral list of licensed inspectors.

Building Education Center

812 Page Street

Berkeley, CA 94710

Telephone: (510) 525-7610


44 The Homeowner’s Guide to Earthquake Safety

California Real Estate Inspection


1445 N. Sunrise Way, Suite 101

Palm Springs, CA 92262

Telephone: (800) 848-7342 (information)

Call for pamphlet describing house inspection

services offered by members and referrals to

qualified members.

Consulting Engineers and Land Surveyors

of California

1303 J Street, Suite 450

Sacramento, CA 95814

Telephone: (916) 441-7991

A referral list for licensed engineers is available.

International Code Council

5360 Workman Mill Road

Whittier, CA 90601-2298

Telephone: (800) 284-4406

Geologic Information

Association of Bay Area Governments

P.O. Box 2050

Oakland, CA 94604

Telephone: (510) 464-7900

A consortium of local governments in the San

Francisco Bay Area, offering a variety of

information, including lists of local resources.

California Geological Survey

California Department of Conservation

801 K Street, MS 12-30

Sacramento, CA 95814

Telephone: (916) 445-1825

The CGS is the state agency responsible for

geological research, mapping, and policy. It

provides maps and other information to the

general public.

Southern California Earthquake Center

University of Southern California

3651 Toursdale Parkway, Suite 169

Los Angeles, CA 90089-0742

Telephone: (213) 740-5843

United States Geological Survey

Earth Science Information Center

345 Middlefield Road

Menlo Park, CA 94025

Telephone: (650) 853-8300

This is the federal agency responsible for

geological and earthquake hazard research,

mapping, and policy. It provides maps and other

information to the general public.

Cities and Counties

Consult your telephone directory under city or

county government listings for the office of

emergency services or disaster management,

city or county building and planning

department, and city or county government


Emergency Planning Information

Federal Emergency Management Agency

Region IX

1111 Broadway, Suite 1200

Oakland, CA 94607

Telephone: (510) 627-7100

FEMA offers a publications lists and referrals to

preparedness organizations. FEMA also provides

information on Federal Disaster Aid Programs that

become available after Federal disasters.

American Red Cross

Consult your telephone directory for the address

and phone number of your local chapter.

The Homeowner’s Guide to Earthquake Safety 45

46 The Homeowner’s Guide to Earthquake Safety



When you sell a home that was built before 1960, you are required to fill out

the form shown on the next page.

?? Sellers must hand buyers a completed disclosure report.

?? Sellers must answer the questions to the best of their knowledge.

?? If a question on the form describes only part of your house—for example if part of your house is

anchored to the foundation and the other part is not—sellers should answer the question with a

“NO” because a portion of the house is not properly anchored.

?? Sellers are not required to remove siding, drywall, or plaster in order to answer the questions.

?? Sellers are not required to hire anyone to inspect their homes.

?? Sellers are not required to fix the weaknesses before they sell their homes.


Residential Earthquake Hazards Report (2005 Edition)




Answer these questions to the best of your knowledge. If you do not have actual knowledge as to whether the weakness exists, answer

“Don’t Know.” If your house does not have the feature, answer “Doesn’t Apply.” The page numbers in the right-hand column indicate

where in this guide you can find information on each of these features.

If any of the questions are answered “No,” the house is likely to have an earthquake weakness. Questions answered “Don’t Know” may

indicate a need for further evaluation. If you corrected one or more of these weaknesses, describe the work on a separate page.

As seller of the property described herein, I have answered the questions above to the best of my knowledge in an effort to disclose fully

any potential earthquake weaknesses it may have.


_____________________________ ______________________________ _________

(Seller) (Seller) Date

I acknowledge receipt of this form, completed and signed by the seller. I understand that if the seller has answered “No” to one or more

questions, or if seller has indicated a lack of knowledge, there may be one or more earthquake weaknesses in this house.

_____________________________ ______________________________ _________

(Buyer) (Buyer) Date

This earthquake disclosure is made in addition to the standard real estate transfer disclosure statement also required by law.

Keep your copy of this form for future reference

Doesn’t Don’t See

Yes No Apply Know Page

1. Is the water heater braced, strapped, or anchored to resist falling during an earthquake?

2. Is the house anchored or bolted to the foundation?

3. If the house has cripple walls:

• Are the exterior cripple walls braced?

• If the exterior foundation consists of unconnected concrete piers and posts, have

they been strengthened?

4. If the exterior foundation, or part of it, is made of unreinforced masonry, has it been


5. If the house is built on a hillside:

• Are the exterior tall foundation walls braced?

• Were the tall posts or columns either built to resist earthquakes or have they been


6. If the exterior walls of the house, or part of them, are made of unreinforced masonry,

have they been strengthened?

7. If the house has a living area over the garage, was the wall around the garage door

opening either built to resist earthquakes or has it been strengthened?

8. Is the house outside an Alquist-Priolo Earthquake Fault Zone (zones immediately

surrounding known earthquake faults)?

9. Is the house outside a Seismic Hazard Zone (zone identified as susceptible to liquefaction

or landsliding)?












The Homeowner’s Guide to Earthquake Safety 47

To be reported on the

Natural Hazards Disclosure


48 The Homeowner’s Guide to Earthquake Safety


for Santa Clara County

The Homeowner’s Guide to Earthquake Safety 49