Reducing Earthquake Losses

September 1995

OTA-ETI-623

GPO stock #052-003-01431-9
ii

Recommended Citation: U.S. Congress, Office of Technology Assessment, Reducing

Earthquake Losses, OTA-ETI-623 (Washington, DC: U.S. Government Printing Office,

September 1995).
iii

oreword

uch of the nation is at risk for earthquakes. Although considerable

uncertainty remains over where and when future earthquakes will

occur, there is general consensus that earthquakes will strike the

United States in the next few decades, causing at a minimum dozens

of deaths and tens of billions of dollars in losses.

Recent congressional hearings on the nation’s earthquake program—the

National Earthquake Hazards Reduction Program (NEHRP)—revealed some

dissatisfaction with the program, yet little agreement on problems or solutions.

The House Committee on Science, Space, and Technology (now the Committee on Science) and its Subcommittee on Science (now the Subcommittee on

Basic Research) asked the Office of Technology Assessment to review the nation’s efforts to reduce earthquake losses, and to provide options for improving

these efforts.

This Report assesses the state of the knowledge, identifies key future challenges in each of the three components of earthquake risk reduction—earth science, engineering, and implementation—and offers policy options to improve

federal efforts. The Report concludes that, since its beginning in 1977, NEHRP

support of efforts to better understand earthquake risk and find ways to reduce

it have advanced our knowledge considerably, although many significant uncertainties remain. However, there is a large gap between knowledge and action—many known technologies and practices are just not used. In addition,

NEHRP suffers from a lack of specific goals, making progress difficult to measure. Policy options for improving federal efforts include changes in the specific activities supported by NEHRP, changes in the management and operations

of the program, and extension of federal activities into areas in which NEHRP

is not currently active.

OTA benefited greatly from the substantial assistance received from many

organizations and individuals in the course of this study. Members of the advisory panel, the reviewers, and many others willingly lent their time and expertise; OTA and the project staff are grateful for their assistance.

ROGER C. HERDMAN

Director
iv

dvisory Panel

Gilbert F. White, Chairman

Professor

University of Colorado

Jesus Burciago

Assistant Fire Chief

Los Angeles County Fire

Department

Charles D. Eadie

Assistant Planning Director

City of Watsonville

Dean C. Flesner

Vice President, Operations

State Farm Fire and Casualty Co.

I.M. Idriss

Professor

Department of Civil and

Environmental Engineering

University of California at Davis

Cynthia Ingham

Assistant Director for Capital

Programs

University of California at

Los Angeles

Tom Jordan

Professor and Department Chair

Department of Earth, Atmospheric

and Planetary Sciences

Massachusetts Institute of

Technology

Joseph Kelly

Senior Consulting Engineer

Port Authority of New York and

New Jersey

Howard Kunreuther

Director of Risk Management

Center

The Wharton School

University of Pennsylvania

Mike Lynch

Earthquake Program Manager

Kentucky Department of

Emergency Services

Steven A. Mahin

Professor

Earthquake Engineering Research

Center

University of California at

Berkeley

Diane F. Merten

Chair

Benton County Emergency

Management Council

Joanne M. Nigg

Director

Disaster Research Center

University of Delaware

Dennis K. Ostrum

Consulting Engineer

Southern California Edison

Vernon H. Persson

Chief, Division of Safety of Dams

California Department of Water

Resources

James Smith

Executive Director

Building Seismic Safety Council

Paul G. Somerville

Senior Associate

Woodward Clyde Consultants

Robert S. Yeats

Professor

Department of Geosciences

Oregon State University

Nabih Youssef

President

Nabih Youssef and Associates

Note: OTA appreciates and is grateful for the valuable assistance and thoughtful critiques provided by the advisory panel members.

The panel does not, however, necessarily approve, disapprove, or endorse this report. OTA assumes full responsibility for the report

and the accuracy of its contents.
v

roject Staff

Peter D. Blair

Assistant Director

Industry, Commerce, and

International Security Division

Emilia L. Govan

Program Director

Energy, Transportation, and

Infrastructure Program

PRINCIPAL STAFF

Paul Komor

Project Director

Kelley Scott

Senior Analyst

Winston Tao

Analyst

Eric Gille

Research Assistant

ADMINISTRATIVE STAFF

Marsha Fenn

Office Administrator

Tina Aikens

Administrative Secretary

Gay Jackson

PC Specialist

Lillian Chapman

Division Administrator

PUBLISHING STAFF

Mary Lou Higgs

Manager, Publishing Services

Denise Felix

Production Editor

Dorinda Edmondson

Electronic Publishing Specialist

Susan Hoffmeyer

Graphic Designer

CONTRACTORS

Florence Poillon

Editor

VSP Associates, Inc.
vi

eviewers

Thomas Anderson

RAND

William Anderson

National Science Foundation

William Bakun

United States Geological Survey

Ian Buckle

National Center for Earthquake

Engineering Research

Riley Chung

National Institute of Standards

and Technology

Caroline Clarke

National Research Council

Brian Cowan

Federal Emergency Management

Agency

Alan Crane

Office of Technology Assessment

Thomas Durham

Central U.S. Earthquake

Consortium

Robert Friedman

Office of Technology Assessment

Kenneth Goettel

Goettel & Horner Inc.

James Goltz

EQE International

Robert Hamilton

U.S. Geological Service

Murray Hitzman

Office of Science and Technology

Policy

Klaus Jacob

Columbia University

James Jirsa

University of Texas

Laurie Johnson

Spangle Associates

Peter May

University of Washington

James Mielke

Congressional Research Service

William Petak

University of Southern California

Christopher Rojahn

Applied Technology Council

Craig Weaver

United States Geological Survey

James Whitcomb

National Science Foundation

Robin White

Office of Technology Assessment

Loring Wyllie

Degenkolb Engineers

Arthur Zeizel

Federal Emergency Management

Agency
vii

1 Summary and Policy Options 1

Introduction to Earthquakes 1

Policy Response to Date: Focus on NEHRP 12

NEHRP Contributions and Challenges 16

Policy Options 20

2 Understanding Seismic Hazards 33

Earthquakes 34

Seismic Hazards Across the United States 41

Earthquake-Related Research in Earth Science 51

Summary and Key Findings 67

3 The Built Environment 71

Casualties 72

Damage to Buildings 74

Damage to Lifelines 86

Accomplishments and Needs of Federally Sponsored

Research 90

4 Implementation 95

The Implementation Process 96

Factors Affecting Implementation 111

How Matters Might Be Improved 119

APPENDICES

A The National Earthquake Hazards

 Reduction Program 125

B Agency Efforts in the Current

 NEHRP 129

C International Earthquake Programs 144

D Acronyms 157

Index 159

ontents
ix

xecutive

Summary

he 1994 Northridge, California, earthquake caused dozens of deaths and over

$20 billion in losses. In 1995 an earthquake in Kobe, Japan, killed more than

5,000 and resulted in losses of well over $100 billion. These disasters show the damage earthquakes can inflict. Although future losses are

uncertain, there is general agreement that damaging earthquakes will strike the United States in

the next few decades, causing at the minimum

dozens of deaths and tens of billions of dollars

in losses.

Since 1977, the federal government has had a

research-oriented program to reduce earthquake

losses. This program—the National Earthquake

Hazard Reduction Program (NEHRP)—has made

significant contributions toward improving our

understanding of earthquakes and strategies to reduce their impact. However, much of the United

States remains at risk for significant earthquake

losses. Risk-reduction efforts lag far behind the

knowledge base created by research; this lag, or

“implementation gap,” reflects the limitations of

NEHRP’s information-based strategy for encouraging nonfederal action. NEHRP also suffers

from a lack of clear programmatic goals.

THE EARTHQUAKE THREAT

Much of the United States is seismically active.

Risks vary widely from region to region:

 The greatest likelihood of repeated economic

losses due to earthquakes is in the coastal regions of California, where moderate earthquakes are frequent and population densities

are high. California, in addition, faces a lower

probability of larger, very damaging earthquakes.

 The Pacific Northwest has experienced rare but

very large earthquakes in the past; the timing of

future earthquakes in this region of the country

is uncertain.

 Quakes in the section of the Intermountain

West running from southern Idaho and western

Montana through Utah and Nevada can endanger communities historically unprepared for

any seismic activity.

 The central United States (chiefly, the region

near the intersection of Missouri, Kentucky,

Tennessee, and Arkansas) and sections of the

eastern United States have experienced infrequent earthquakes in the past. Future occurrences are very uncertain, but if and when they

do occur, losses could be quite high as these

areas are largely unprepared.

The primary hazard associated with earthquakes is ground shaking, which damages and destroys buildings, bridges, and other structures.

Ground shaking also causes liquefaction, landslides, and other ground failures that endanger

structures. This damage and destruction has both
x

short- and long-term implications. In the short

term, people are killed and injured by falling

buildings and other objects. The fires associated

with earthquakes are often difficult to fight because water pipes have been broken and roads

have been blocked by debris. In the long term, the

costs of repair or replacement, coupled with the

loss of customers and employees (e.g., due to impassable roads), can force businesses and industries to close. Local governments may be forced to

cut services to cover the costs of infrastructure repair. And if reductions in the supply of housing

lead to higher rents, there may be increased homelessness.

THE U.S. POLICY RESPONSE TO DATE

The federal government currently responds to the

earthquake threat with a number of policies and

programs. Its primary effort is the National Earthquake Hazard Reduction Program (NEHRP), established in 1977 to “reduce the risks of life and

property from future earthquakes in the U.S....”

The program combines the efforts of four federal

agencies:

 the U.S. Geological Survey (USGS),

 the National Science Foundation (NSF),

 the Federal Emergency Management Agency

(FEMA), and

 the National Institute of Standards and

Technology (NIST).

NEHRP’s original charter included wide-ranging provisions for earthquake prediction, earthquake control, and vigorous implementation of

seismic safety knowledge. In practice, however,

the program has centered on the performance and

dissemination of science and engineering research. Thus, 64 percent of the NEHRP budget

goes (via USGS and NSF) to research in the earth

sciences, and another 14 percent supports engineering research; the remaining 22 percent of the

budget goes to “implementation” activities such

as technical translation, education, and outreach.

NEHRP: PROGRESS AND PROBLEMS

NEHRP-sponsored research has yielded an

impressive list of accomplishments. Although

past accomplishments do not ensure future ones,

it is clear that NEHRP has led to significant advances in our knowledge of both earth science

and engineering aspects of earthquake risk reduction. For example, NEHRP-supported research led to recognition of the seismic risk in the

Pacific Northwest, and NEHRP funding helped

develop the knowledge base that now makes it

possible to design and construct new buildings

that are unlikely to collapse in earthquakes. Although NEHRP is principally a research program—over 75 percent of its funds are directed

toward research—it has made some contributions

to the implementation of earthquake mitigation,

as well. Thus, for example, we now have model

building codes that reflect a national consensus on

new building seismic design, as well as several interdisciplinary centers that work to translate research results into useful information for

decisionmakers.

Despite these successes, however, earthquakes

continue to cause massive losses in the United

States. The 1994 Northridge earthquake caused

more than $20 billion in losses, and scenarios of

possible future U.S. earthquakes suggest that

thousands of casualties and tens or even hundreds

of billions of dollars in losses may occur. Although there is no consensus on what level of loss

is acceptable,1 there is clearly a significant remaining exposure to earthquake damage—

due in large part to a failure to implement

known technologies and practices. Many communities, especially in California, have taken

steps to reduce earthquake losses, but there still remains a large gap between what current knowledge says could be done and what actually is done.

The failure to implement known technologies

and practices, or “implementation gap,” is a direct

result of NEHRP’s approach to reducing earth1 Although no losses would seem desirable, achieving zero losses would be either impossible or impractically expensive.
xi

quake losses. NEHRP’s approach can be thought

of as supplying information on earthquake risks

and possible countermeasures to those who may

wish to mitigate. By supplying this information,

the program hopes to motivate individuals, organizations, and local and state governments toward

action while providing guidelines on how to proceed. This approach implicitly assumes that the

interest or incentive for mitigation is sufficient for

people to act on such information. However, the

current paucity of mitigation activities suggests

that individuals, organizations, and local and state

governments lack sufficient incentives for mitigation. Whether or not the federal government

should play a role in ensuring that there are sufficient incentives for mitigation is a sensitive policy

question. In any case, NEHRP’s approach of

supplying information alone clearly limits the

program’s impact.

NEHRP faces serious operational problems as

well. Numerous congressional reports and expert

review panels have noted that NEHRP lacks

clear and workable goals and strategies. Although NEHRP’s authorizing legislation does set

broad overall objectives for the program, actual

NEHRP spending by the four participating agencies does not suggest any unified multiagency

agreement on specific goals, strategies, or priorities. In the absence of a multiagency consensus on

NEHRP goals and strategies, each of the four participating agencies (USGS, NSF, FEMA, and

NIST) has developed a portfolio of NEHRP activities that reflects its own agency mission and priorities. In addition, the lack of agreement on goals

and strategies makes it difficult to judge the impact or success of the overall program, since there

are few criteria by which to measure performance.

POLICY OPTIONS

OTA has identified several policy options that

Congress could consider to improve federal efforts to reduce earthquake losses. Three general

types of policy options are discussed:

 One type of option involves changes in the specific research and other activities that NEHRP

undertakes. OTA identifies key research and

implementation needs that NEHRP could address within its current scope.

 The second type of option involves management and operational changes in NEHRP. Such

changes could make NEHRP a more efficient,

coordinated, and productive program.

 The third type of option includes changes to

federal disaster assistance and insurance, regulation, and financial incentives. Such changes

are outside the current scope of NEHRP and

would represent a significant change in direction for the program. However, such changes

are necessary to yield major national reductions in earthquake risk.

CHANGES IN SPECIFIC ACTIVITIES

OF NEHRP

❚ Earth Science Research

Decisions about what earth science research to

support should be made in the context of the goals

of the earthquake program. If Congress would like

NEHRP to reduce earthquake losses in the short

term and also to focus on implementing known

technologies and practices, then the earth science

research portfolio should favor more applied,

short-term work such as microzonation, ground

motion mapping, and hazard assessment. In contrast, if Congress views NEHRP as a program for

reducing earthquake hazards over the long term,

it would be appropriate to retain the current focus

on basic earth science research.

❚ Earthquake Engineering Research

A new structure that meets current seismic building codes will be very resistant to collapse due to

earthquakes. The construction of buildings that

are resistant to collapse is a great technical accomplishment in which NEHRP played a considerable

role. Since this has been achieved, it is time to consider moving some resources to the next research

challenge—reducing earthquake-related structural, nonstructural, and contents damage.

Much of the risk of both structural failure and

nonstructural and contents damage lies in existing

structures, which do not incorporate current codes

and knowledge. Relatively few of these structures
xii

have been retrofitted to reduce risk; and where retrofits have been performed they have often been

expensive, complex, and of uncertain benefit.

More research is needed to improve retrofit methods.

❚ Implementation

One of NEHRP’s most promising implementation

activity is to directly assist communities in their

efforts to understand earthquake risk and to devise

mitigation options. Analytic tools to estimate

likely losses in the event of a future earthquake

and to predict the likely benefits of mitigation

would be of great help to communities.

FEMA currently has several programs intended to promote implementation of known mitigation technologies and practices. Very few of

these programs have been evaluated carefully in

the past, leaving current program planners with

little guidance as to what works, what does not,

and why. All mitigation programs should be evaluated carefully, and the results should be used to

improve, refocus, or—if necessary—terminate

programs.

In addition to direct support for implementation, NEHRP also supports some research into the

behavioral, social, and economic aspects of mitigation. Further research of this type could improve our understanding of some key issues that

currently hinder mitigation.

MANAGEMENT AND

OPERATIONAL CHANGES

NEHRP spending by the four participating agencies suggests a loosely coordinated confederation

of agencies with no overarching agreement on

specific goals, strategies, or priorities for NEHRP.

One policy option is for FEMA, as the lead

agency, to work with other NEHRP agencies and

with the professional earthquake community to

come up with specific goals and priorities for

NEHRP. Defining overarching goals for NEHRP

would not be easy and would have to address the

difficult issue of acceptable risk. Yet it is necessary for NEHRP to move beyond a loose confederation of four agencies. Congress could require

FEMA to report on progress toward defining and

meeting specific goals for NEHRP. Since FEMA

has no explicit budgetary or other control over the

other agencies that participate in NEHRP, Congress may wish to provide oversight to ensure that

all these agencies work toward defining and meeting the agreed-on goals.

The continuing congressional dissatisfaction

with FEMA’s management and coordination of

NEHRP has led some to consider transferring lead

agency responsibility from FEMA to another

agency. OTA’s finding that implementation is

emerging as NEHRP’s key challenge, however,

suggests that, of the four principal NEHRP agencies, FEMA appears to be the most appropriate

lead agency. FEMA has the most direct responsibility for reducing losses from natural disasters; it

is in direct contact with state, local, and private

sector groups responsible for reducing earthquake

risks; it has a management rather than research

mission; and it coordinates regularly with other

agencies in carrying out its mission. The other

NEHRP agencies are principally involved in

research and therefore may find it difficult to develop the strong implementation component necessary to lead the program. One policy option

would be for Congress to allow FEMA to continue

as lead agency but to provide frequent oversight to

ensure that lead agency responsibilities are carried

out.

BEYOND THE CURRENT NEHRP

Congress could consider other policy options that

go beyond the scope of the current NEHRP. These

include using federal disaster assistance as an incentive for mitigation, an increased federal role in

disaster insurance, increased regulation, and

greater use of financial incentives to promote mitigation. These policy options have the potential to

significantly increase implementation of seismic

safety knowledge—something NEHRP, in its current form, is unlikely to accomplish. However,

these options would likely require new legislation

and would be a significant departure from current

policy. They would also be quite controversial.
xiii

In considering these options, a central issue is:

What is the appropriate role of the federal government in mitigation? Some argue that increased investment in mitigation by the federal

government would save money by reducing future

disaster outlays. Others argue that the very existence of federal disaster assistance programs

creates disincentives for mitigation. Still others

argue that mitigation tools, notably land-use planning and building regulation, are state and local issues in which an increased federal role is

inappropriate. These arguments involve different

political and philosophical beliefs; OTA does not

attempt to resolve them but rather suggests that

policymakers consider the policy options in light

of their own beliefs.

Insurance and disaster assistance can be a vehicle for mitigation, as well as a disincentive

against mitigation, depending on how the program is structured. Congressional decisions as to

the fate of hazards insurance legislation will involve many issues, most of which are beyond the

scope of this report. With respect to mitigation,

however, it is clear that insurance can be a strong

incentive for earthquake mitigation—if the cost of

insurance reflects the risk. In addition, social science research suggests that individual mitigation

decisions are not made on an economically rational cost-benefit basis but are considerably more

complex. Insurance programs should recognize

these complexities.

One policy option, largely outside the scope of

NEHRP as currently defined, would be for the

federal government to take a stronger position on

implementation via regulation. In the current

policy environment, regulation in the form of

building codes is the most widely used mitigation

tool, but it is performed at the state or local level.

The federal government plays only an indirect role

by providing technical support for code development and implementation. In addition, Executive

Order 12699 (issued January 5, 1990) requires

that new buildings constructed with federal assistance meet current codes. A more aggressive

policy option would be to require states and localities to adopt model building codes, or demonstrate

a minimum level of code enforcement, as a condition for receiving federal aid. Nonstructural mitigation efforts could be advanced through an

executive order addressing this problem in federal

buildings.
Summary

 and

 Policy Options

arthquakes have caused massive death and destruction,

and potentially damaging earthquakes are certain to occur

in the future. Although earthquakes are uncontrollable,

the losses they cause can be reduced by building structures that resist earthquake damage, matching land use to risk, developing emergency response plans, and other means. Since

1977, the federal government has had a research oriented program

to reduce earthquake losses—the National Earthquake Hazards

Reduction Program (NEHRP). This program has made significant contributions toward improving our understanding of earthquakes and strategies to reduce their impact. Implementing action

based on this understanding, however, has been quite difficult.

This chapter provides an introduction to earthquakes: a summary of the earthquake hazard across the United States, a review

of the types of losses earthquakes cause, a discussion of why

earthquakes are a congressional concern, and an introduction to

mitigation—actions taken prior to earthquakes that can reduce

losses when they occur. The federal policy response to date,

NEHRP, is then described and reviewed. Finally, specific policy

options for improving federal efforts to reduce future earthquake

losses are presented.

INTRODUCTION TO EARTHQUAKES

❚ When and Where Earthquakes Occur

Many parts of the United States are subject to earthquakes, which

occur when stress accumulates in underground rocks. This buildup of stress typically reflects the slow but continuous motion of

the earth’s outermost rocky layers, large sections of which drift

| 1
2 | Reducing Earthquake Losses

about the globe as moving tectonic plates. Where

adjacent plates collide or grind against one another, rocks are highly stressed, and this stress is released in sudden shifts in the earth’s surface. As a

result, plate boundaries are the primary breeding

ground for earthquakes.

One such boundary lies in California, where

two major plates slide against one another along

the San Andreas fault. Stresses along this and

associated faults make California subject to frequent and sometimes powerful earthquakes. In the

north of the state, detailed earth science research

suggests a 67 percent probability of one or more

earthquakes of magnitude 71 or greater in the

San Francisco Bay area by 2020.2 To the south,

where hazard assessments are less certain due to

the geologic complexity of the Los Angeles region, a recent report estimates an 80 to 90 percent

probability of a magnitude 7 or greater earthquake in southern California before 2024.

3

The colliding of adjacent plates produces extremely powerful earthquakes along the Alaskan

coast, one of which severely damaged the city of

Anchorage in 1964. A similar earthquake threat

has recently been recognized in the Pacific Northwest states of Oregon and Washington: according

to a 1991 study, a great earthquake (magnitude

8 to 9) is possible in the Pacific Northwest;

magnitude 6 to 7 earthquakes have occurred in

this area in the past and are likely to occur in

the future.

4

Other parts of the United States are also seismically active—due not to plate collisions, but to

other processes not well understood. Regions experiencing damaging earthquakes in the recent past include parts of the Intermountain

West (i.e., sections of Utah, Idaho, Wyoming,

Montana, and Nevada); the Mississippi Valley

region of the central United States (centered on

an area north of Memphis, Tennessee); and

cities on the Atlantic seaboard (notably

Charleston, South Carolina, and Boston, Massachusetts). (See figure 1-1.) Earthquakes in

these regions (called intraplate earthquakes because they occur far from current plate boundaries) are infrequent but potentially powerful.

❚ Earthquake Effects

Earthquakes can cause deaths, injuries, and damage to buildings and other structures, and may inflict a wide range of longer term economic and

social losses as well.5 Although estimating future

losses is very uncertain (see box 1-1), there is general agreement that in the next 50 years or so one

or more damaging earthquakes will occur in

the United States, resulting in at least hundreds

of deaths and tens of billions of dollars in

losses. Larger events, involving thousands of

deaths and hundreds of billions of dollars in losses

(such as that seen in the 1995 earthquake in Kobe,

Japan), are also possible, although scientific uncertainty makes it difficult to estimate their likelihood.

The primary hazard associated with earthquakes is ground shaking, which can damage or

destroy buildings, bridges, and other structures.

Figure 1-2 shows expected ground motions from

1 A magnitude 7 earthquake is one large enough to cause serious damage. For comparison, a magnitude 5 will cause slight damage, and a

magnitude 8 or greater can cause total damage. See chapter 2 for a discussion of earthquake magnitude scales.

2 Working Group on California Earthquake Probabilities, Probabilities of Large Earthquakes in the San Francisco Bay Region, California,

U.S. Geological Survey Circular 1053 (Washington, DC: U.S. Government Printing Office, 1990).

3 Working Group on California Earthquake Probabilities, “Seismic Hazards in Southern California: Probable Earthquakes, 1994-2024,”

Bulletin of the Seismological Society of America, vol. 85, No. 2, April 1995, p. 379.

4 Kaye M. Shedlock and Craig S. Weaver, Program for Earthquake Hazards Assessment in the Pacific Northwest, U.S. Geological Survey

Circular 1067 (Washington DC: U.S. Government Printing Office, 1991), p. 1.

5Damage generally refers to the direct physical effects of earthquakes, while losses include all the societal effects including deaths, injuries,

direct financial costs, indirect costs (such as those resulting from business interruptions), and social impacts such as increased homelessness.
Chapter 1 Summary and Policy Options 13

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4 Reducing Earthquake Losses

Dependable estimates of likely losses from earthquakes would be useful in developing appropriate policies for earthquake mitigation—for example, by allowing comparisons with other threats to life and property. Unfortunately, the huge uncertainties in the Iocation, timing, and magnitude of earthquakes themselves;

in the response of the built environment to earthquakes; and in the inventory of structures that might be

damaged make estimating future losses very difficult. ’

Despite these difficulties, some estimates of future losses have been made. The results of several such

studies are summarized here to provide a sense of the probable range of such losses. These studies cannot be compared, since they examine different geographical areas and different types of losses. As a

group, however, they give some indication of the expected scale of future losses A 1992 study for the

property Insurance industry estimated losses for several geographic areas, including sections of California, the Pacific Northwest, and the central United States. Total losses due to building damage for a magnitude 7.8 earthquake on the northern section of the San Andreas fault near San Francisco, for example,

were estimated at $35.2 billlon.2 This does not include public sector losses, such as those due to damaged

schools or bridges. Another study estimated both dollar losses and fatalities for scenario earthquakes in

California and in the central United States. For the larger earthquakes (magnitude 7.5 or greater), losses

were on the order of tens of billions of dollars and fatalities in the thousands.3

Much more dramatic results can be seen from attempts to predict damages from worst-case earthquakes-great earthquakes that strike close to population centers. A repeat of the 1906 magnitude 8.3

earthquake in San Francisco could cause 2,000 to 6,000 deaths.4 A repeat of the 1811 central U S earthquake could cause more than $100 billion in damage due to ground motion 5

An alternate method for arriving at an overall sense of future earthquake damage IS to examine the

damage caused by past earthquakes. As shown in the table below, U.S. earthquakes since 1900 have, in

total, resulted in about 1,200 deaths and $40 billion in damage. However, extrapolating from historical

earthquake damages IS problematic for several reasons”

■ All else equal, damage will Increase over time as both population and urbanization Increase—especially

in the western United States, which has experienced rapid population growth in recent years

■ The recent historical record shows no major earthquakes in the eastern United States, although such

earthquakes have occurred and may occur again.

1 According to a National Academy of Sciences report, “even using the best of today’s methods and the most experienced expert

opinion, losses caused by scenario earthquakes can only be estimated approximately Overall property loss estimates are often uncertain by a factor of 2 to 3, and estimates of casualties and homeless can be uncertain by a factor of 10 “ National Research Council,

Estimating Losses from Future Earthquakes (Washington, DC National Academy Press, 1989), p 3

Although loss estimation methods are still relatively crude and hampered by lack of data, recent technological advances suggest

that loss estimation may soon be a more useful and accurate policy analysis tool The rapid development of computer hardware and

software-specifically the ability to store large amounts of data on CD-ROMs or tapes, and the availability of software that can make

sense of these data—has made it possible to manage detailed databases of all structures in specific geographic areas Geographical information systems are now being used in combination with probabilistic ground motion data to yield useful forecasts of Iikely and

worst-case earthquake damages The Federal Emergency Management Agency, for example, IS supporting the development of a

computer-based loss estimation tool that would be available to city planners and emergency managers on their desktop computers

2 Risk Engineering, Inc. , “Residential and Commercial Earthquake Losses in the U S ,“ prepared for the National Committee on

Property Insurance, Boston MA, May 3, 1993 Zero-deductible assumption “Loss” does not reflect deaths or injuries

3 R Litan et al , “Physical Damage and Human Loss The Economic Impact of Earthquake Mitigation Measures, ” prepared for The

Earthquake Project, National Committee on Property Insurance, February 1992 Base-case scenarios, without mitigation Expected

losses do not include deaths or injuries.

4 See “’Repeat’ Quakes May Cause Fewer Deaths, More Damage, ” Civil Engineering, November 1994, pp. 19-21

5 National Academy of Sciences, The Economic Consequences of a Catastrophic Earthquake, Proceedings of a Forum, Aug. 1

and 2, 1990 (Washington, DC National Academy Press, 1992), p 72
Chapter 1 Summary and Policy Options 15

Major U.S. Earthquakes, 1900-94

Damages

Year LoCaliforniation Deaths (million $1994)

1906

1925

1933

1935

1940

1946

1949

1952

1952

1959

1964

1965

1971

1979

1983

1987

1989

1992

1992

1993

1993

1994

TOTAL

San Francisco, California

Santa Barbara, California

Long Beach, California

Helena, Montana

Imperial Valley, California

Aleutian Islands, Alaska

Puget Sound, Washington

Kern County, California

Bakersfield, California

Hebgen Lake, Montana

Anchorage, Alaska

Puget Sound, Washington

San Fernando, California

Imperial County, California

Coalinga, California

Whittier Narrows, California

Loma Prieta, California

Petrolia, California

Landers, California

Scotts Mills, Oregon

Klamath Falls, Oregon

Northridge, California

KEY n/a = not available

SOURCE Office of Technology Assessment, 1995

700

1 3

120

4

8

n/a

8

12

2

2 8

131

8

6 5

nla

o

8

6 3

0

1

n/a

2

5 7

1,225

6,000

60

540

40

7 0

200

220

350

6 0

n/a

2,280

7 0

1,700

6 0

50

450

6,870

7 0

100

3 0

1 0

20,000

39,160

■ Some argue that in certain regions, more and larger earthquakes should be expected m the future.6

■ A single event can influence the data significantly. More than half the deaths since 1900 occurred in just

one incident—the 1906 San Francisco earthquake, while about half of the total dollar damages were

from the 1994 Northrldge event. This demonstrates the “lumpiness” of earthquakes: the deaths and

losses occur not in regular intervals, but in large and catastrophic single events.

= On the other hand, new buildings meeting current seismic codes are much more resistant to structural

failure than old buildings, which should help to reduce fatalities.

The uncertainties both in projecting losses and in extrapolating historical data make predicting future

losses difficult. It is generally agreed, however, that in the next 50 years or so, damaging earthquakes WIII

occur m the United States, resulting in at least hundreds of deaths and tens of billions of dollars in losses.

Larger events, involving thousands of deaths and hundreds of billions of dollars in losses, are possible,

although less likely.

6 J DoIan et al,, “prospects for Larger or More Frequent Earthquakes m the Los Angeles Metropolitan Rewn,” sC/e~Ce Vol 267,

Jan 13, 1995, pp 199-205
6 I Reducing Earthquake Losses

Failure of the ground itself can make an otherwise sound

building unusable.

future earthquakes in the United States. Ground

shaking can also cause liquefaction, landslides,

subsidence, and other forms of ground failure that

can endanger even the best-built structures, and

moreover may generate coastal tsunamis (great

surges of water popularly known as tidal waves).

The damage and destruction wrought by earthquakes has both short- and long-term implications. In the short term, people are killed and

injured by collapsing buildings and falling debris.

The fires that can result may be difficult to fight

due to broken water pipes and roads blocked by

debris. In the long term, the costs of repair or replacement coupled with the loss of customers and

employees (e.g., due to impassable roads) can

force businesses and industries to relocate or

close. Local governments may be forced to cut

services to cover the costs of infrastructure repair,

and housing rents can increase (due to reductions

in supply), leading to increased hopelessness.

Deaths

A single earthquake can cause thousands of deaths

and tens of thousands of injuries. In just the last

decade—1980 to 1990-earthquakes killed almost 100,000 people worldwide. About twothirds of these deaths occurred in just two

catastrophic earthquakes-over 25,000 deaths in

Armenia 6 in 1988 and 40,000 in Iran in 1990.7

The historical record of U.S. earthquake fatalities is less unfortunate. Since 1900, about 1,200

people have died in U.S. earthquakes (see box

1-l). Most of these earthquakes occurred in regions that were, at the time, sparsely populated.

Thus, the low fatality figures for earthquakes from

1900 to 1950 are not surprising. However. even

those quakes occurring since 1950 in heavily populated areas of California have had relatively low

fatalities, due largely to the fact that many buildings and other structures in California are built to

resist seismic collapse. 8 Casualties from future

earthquakes are uncertain. One estimate found

that a repeat of the 1906 San Francisco earthquake

would cause 2,000 to 6,000 deaths;9 another study

found that a large earthquake striking the New

Madrid region of the central United States would

result in 7,000 to 27,000 deaths. 10

Most deaths in earthquakes occur when

structures collapse. In Armenia, for example,

6 L. Wyllie, Jr., President, Earthquake Engineering Research Institute, personal communication, May 11, 1995.

7 B. Bolt, Earthquakes (New York, NY: W. H. Freeman and Co., 1993), pp. 272-273.

8 There is an element of luck here as well. The Loma Prieta earthquake, for example, struck during the world series baseball game when

roads were relatively empty. Fatalities would have been in the hundreds, perhaps higher, if traffic had been at more typical weekday levels.

9 See “’Repeat’ Quakes May Cause Fewer Deaths, More Damage,” Civil Engineering, November 1994, pp. 19-21.

10 National Academy of Sciences, The Economic Consequences of a Catastrophic Earthquake, proceedings of a Forum, Aug. 1 and 2, 1990

(Washington DC: National Academy Press, 1992), p. 68.
Chapter 1 Summary and Policy Options 17

u < 5%

——.—

NOTE Map shows expected ground acceleration as a percentage of gravitational acceleration (1 OOYO = 1 0 G) This expected acceleration IS for

O 3-second period shaking and has a 107. probability of being exceeded m 50 years

SOURCE Off Ice of Technology Assessment, 1995, based on U S Geological Survey

most of the deaths were caused by people being Injuries

crushed under collapsing buildings. Nearly all of In a typical earthquake, many more buildings are

the deaths in the 1989 Loma Prieta earthquake damaged than are destroyed. It is this damage to

were due to structural collapse. 11 The second ma- buildings and their contents that causes most injujor cause of death in earthquakes is fire. In the ries. In the 1989 Loma Prieta earthquake, for ex1923 Tokyo earthquake, for example, many of the ample, 95 percent of the injuries did not involve

143,000 deaths were caused by the firestorms that structural collapse. 13 These injuries are caused by

occurred after the quake. 12

—

I I M, ~urkl~ ~n~ c, Thle], ‘sImproving Measures To Reduce Earthquake Casualties. “ Earthquake Spectra, vol. 8, No. 1, February 1992,

p. 98.

I z ~olt, see footnote 7. PP. 219’ 27”

1~ Durkln and Thiel, see foo[note” ] I
8 I Reducing Earthquake Losses

Earthquake injuries are often the result of shifting contents

falls, getting struck by falling or overturned objects, or getting thrown into objects. For example,

bookcases and file cabinets can tip over, tumbling

books onto people and knocking over other objects, and lighting fixtures and ceiling tiles can

come down on people’s heads.

Damage to Buildings

Earthquakes can cause four types of damage to

buildings: 1) collapse—tile destruction of an entire building, with the death of most of its occupants; 2) structural damage, which leaves the

building standing but still unsafe; 3) nonstructural

damage to walls, water pipes, windows, and so

forth; and 4) damage to contents. The costs of such

damage are borne by the building owners and, if

the building is insured, by the insurance industry.

As discussed later, these costs are in turn shared in

many cases by the federal government through

disaster assistance programs.

Damage to Lifelines

Lifelines—transportation, energy, water, sewer,

and telecommunications systems—are often

damaged by earthquakes. These systems can be

very expensive to repair; yet even those costs may

be dwarfed by the costs of service interruptions. In

the short term, interruptions in water supply can

cause a city to bum down, and breaks in key transportation links can block access by emergency vehicles. As with buildings, the costs of repair

typically fall on the owner (which for many lifelines is the state or local government), the insurance industry if the system is insured, and the

federal government through disaster assistance

programs.

Other Costs

In addition to deaths, injuries, and damage to

buildings and lifelines, earthquakes also cause

losses of a different sort. These losses, sometimes

called “economic,” “indirect,” or “social,” include the following:

People cannot get to work when a transportation system is damaged; as a result, businesses

must close or reduce their services.

Basic services such as energy and communications are interrupted, making economic activity

difficult or impossible.

Small business with limited access to capital

often cannot survive the combination of loss of

business and capital requirements to repair

damage.

However, there are those who benefit from earthquakes as well. A severe earthquake is typically

followed by a large inflow of money from the government. Construction and associated businesses,

such as building materials and architectural firms,

experience large increases in business. Housing

vacancy rates go down.

The net longer-term economic effects of earthquake are not clear. As a recent review noted,”. . .

no systematic research has been conducted on the

overall economic effects of a major disaster on the

public sector, much less on trying to project these
Chapter 1 Summary and Policy Options 19

impacts for a future catastrophic earthquake. . . .”1 4

Clearly, an earthquake has distributional impacts

(e.g., damaged businesses lose and construction

companies gain), but the net effects are difficult to

measure.

Social losses

Often missing from attempts to measure the effects of earthquakes are very real social losses.

Low-income housing, which is often concentrated

in older buildings that are less resistant to seismic

damage, may be the most severely affected, leading to increases in hopelessness and dislocation.

Communities faced with the huge costs of repairing earthquake-induced damage to public property maybe forced to reduce other services. Housing

rents may increase (because of a reduction in supply), resulting in hardship for low-income households. The trauma of seeing one’s home or

livelihood threatened or destroyed can be severe.

Damaged structures may be left unrepaired for

years, creating an eyesore and detracting from a

sense of community.

■ Congressional Interest in Earthquakes

The large and continuing losses from earthquakes

are of concern to Congress for several reasons.

The federal government has long assumed some

responsibility for responding to disasters that are

beyond the abilities of individuals and local

governments to manage. Earthquakes can easily

overwhelm state and local disaster response capabilities, and without federal support, many more

people would suffer great personal and financial

pain. In recent years, however, the financial costs

of federal earthquake relief have been very high.

In two recent U.S. earthquakes-Loma Prieta

(1989) and Northridge (1994)—Congress passed

supplemental appropriations bills to help pay for

the losses. For Northridge, this bill totaled about

$10 billion (although not all of it was to be spent

on the Northridge quake). l5 Future earthquakes

14 National Academy of Sciences, see footnote 10, p. 5.

The 1994 Northridge, California, earthquake caused

extensive damage to this parking garage.

Nonstructural damage can be very costly and disruptive.

may well receive the same response from Congress—a large supplemental appropriation that

strains the federal budget and aggravates the deficit. Since the U.S. government pays much of the

costs of earthquakes, it is in the government’s financial interest to understand what these costs are

due to and how they could be reduced.

In addition to the intermittent large supplemental appropriations to cover some of the costs of

earthquakes, the federal government currently

spends about $100 million annually on NEHRP—

15 “Disaster Relief: A Trial Run for the Deficit Battle,” Congressional Quarterly, Feb. 12, 1994, p. 319.
10 I Reducing Earthquake Losses

The San Francisco-Oakland Bay Bridge was damaged in the

1989 Loma Prieta earthquake.

Earthquakes often disrupt business services such as

banking.

the national program intended to reduce earthquake losses (NEHRP is discussed in detail

below). Congressional oversight of this program

is needed to ensure that this money is well spent.

The federal government’s own property—federal buildings and federally sponsored or supported highways, dams, and other projects—is

also at risk from earthquakes. About 40 percent of

federal buildings and employees are located in

seismically active areas, and about 15 percent are

located in areas of high or very high seismic hazard. 16 A recent General Accounting Office report

found that, “agencies’ efforts to reduce building

vulnerability have been limited.” 17 Reducing this

vulnerability is in the federal government’s interest. 18

■ Mitigation: Reducing the Losses

Although earthquakes are unavoidable and uncontrollable, much of the losses they cause are

not. Numerous technologies and practices are

available that can sharply reduce damage and

casualties from earthquakes. Some of these are already in use—largely in California, which leads

the nation in earthquake mitigation. However,

many technologies are underutilized due to lack of

incentives, lack of information, and other barriers

(discussed in chapter 4).

●

■

■

■

■

Mitigation measures (i.e., actions) include:

incorporating seismic design features into new

buildings and lifelines;

retrofitting existing buildings and lifelines to

improve resistance to seismic forces;

securing nonstructural components so that they

do not fall or become sources of injury in an

earthquake;

matching land use to the hazard; and

developing response plans that ensure the

availability of fire, ambulance, and other resources as needed.

There are numerous tools, or levers, to promote

these measures, including:

building codes that set minimum seismic requirements for new construction;

land-use regulations that steer inappropriate

development away from dangerous areas (e.g.,

prohibiting residential construction in landslide-prone areas);

l6 U.S. Congress, General Accounting Office, “Federal Buildings: Many Are Threatened by Earthquakes, but Limited Action Has Been

Taken,” GAO/GGD-92-62, May 1992.

17 Ibid.

18 The federal government has taken some steps, including the signing of two executive orders, to reduce the risk in federal buildings
Chapter 1 Summary and Policy Options | 11

 provision of information such as detailed

ground motion maps to decisionmakers;

 public education programs;

 financial incentives, such as insurance, that

promote the use of mitigation measures; and

 research, to better define the risk and improve

methods to reduce it.19

Clearly, mitigation can save lives and reduce

losses. The relatively low fatalities in the two recent California earthquakes, for example, are due

largely to the fact that for many years California

has had a building code that requires the use of

seismic design principles in new building

construction. However, mitigation has its challenges as well; these are summarized below.

Knowledge Gaps and Uncertainties

Although considerable progress has been made in

defining the earthquake hazard and in understanding how to design structures to reduce the chances

of collapse, much remains unknown; these uncertainties make mitigation more difficult. Key

knowledge and understanding gaps include:

 the earthquake hazard outside California—the

probabilities, magnitudes, and resulting

ground motions of potentially damaging earthquakes;

 how to design buildings to minimize structural

and nonstructural damage (as distinguished

from minimizing the chances of collapse);

 low-cost and effective ways to retrofit existing

structures to reduce earthquake damage; and

 the costs and benefits of mitigation.

Information Access

Decisionmakers may not have access to the latest

information, or current knowledge may not be

available in a useful and understandable form. For

example, structural engineers may not be trained

in the latest thinking on seismic design, and homeowners may not know that gas water heaters

should be secured to the wall. Similarly, city planners and land-use zoning officials may not have

accurate and readily understandable risk maps

showing which areas of the city are susceptible to

earthquake-induced liquefaction or landslides.

Costs, Benefits, and Incentives

The use of mitigation technologies and practices

increases upfront (initial) costs. These costs can

be calculated with reasonable certainty, and they

can be considerable. For example, the estimated

cost to seismically retrofit buildings at one campus of the University of California is $500 million.20 The benefits of mitigation—avoided

damage—occur in the future and are, like earthquake risk, uncertain. Forecasting the benefits of

mitigation in just one building requires information on future earthquake timing, effects, damage

without mitigation, and reduction in damage due

to mitigation. These are all uncertain, and this uncertainty makes it very difficult to determine the

net benefits (i.e., benefits minus costs) of mitigation. Although there is general agreement in the

professional community that greater mitigation

would have positive net financial benefits (i.e.,

benefits would exceed costs), this can be difficult

to demonstrate due to the numerous uncertainties.

Even when mitigation clearly provides positive net benefits, many individuals and institutions demand rapid paybacks from investments

(i.e., they heavily discount future returns) and are

less likely to invest in mitigation since its benefits

are long term. For example, if a building owner

expects to own a building for only a short time, he

or she may see the probability of an earthquake in

that time period as low and therefore not justifying

19 The earthquake hazard is ground shaking, liquefaction, and other natural phenomena that cannot be controlled; while the risk is the potential for losses and can be controlled.

20 C. Ingham and T. Sabol, “A Comprehensive Seismic Program: The Experience at UCLA,” in Proceedings of the Fifth U.S. National Conference on Earthquake Engineering, July 10-14, 1994, Chicago, IL (Oakland, CA: Earthquake Engineering Research Institute, 1994), vol. 3, p.

842.
12 I Reducing Earthquake Losses

140j Al

20

1

0! 1 1 I I I 1 I [ [ I I ! 1 1 I

1978 80 82 84 86 88 90 92 94

Fiscal year

SOURCE Off Ice of Technology Assessment, 1995, based on NEHRP

budget data

mitigation. In addition, the costs and benefits of

mitigation may fall on different groups. For example, if an individual believes that an insurance

company or the federal government is likely to

pay for earthquake damage, there is less financial

incentive to mitigate.

POLICY RESPONSE TO DATE:

FOCUS ON NEHRP

The federal government currently responds to the

earthquake threat with a number of policies and

programs. Its primary effort is NEHRP, established in 1977 to “reduce the risks of life and property from future earthquakes in the U.S. . . .“21

This program combines the efforts of four federal

agencies—the U.S. Geological Survey (USGS),

the National Science Foundation (NSF), the Federal Emergency Management Agency (FEMA),

and the National Institute of Standards and

Technology (NIST)—in an effort to reduce earthquake risk through research, development, and

implementation.

This Office of Technology Assessment (OTA)

report was prepared in response to a request by the

House Committee on Science for use in reauthorizing the NEHRP program. Therefore, it focuses

on NEHRP. However, the federal government has

a number of other policies and programs for addressing earthquakes. Although these are largely

response and recovery programs, they have some

effect on mitigation. The principal federal disaster

program is the Robert T. Stafford Disaster Relief

and Emergency Assistance Act,** which authorizes the President to issue major disaster or emergency declarations, sets eligibility criteria, and

specifies the types of assistance that federal agencies may offer. In the event of a presidentially declared disaster, the region becomes eligible for a

number of programs, many of which are operated

by FEMA. In the case of large disasters such as the

1989 Loma Prieta and 1994 Northridge earthquakes, Congress passed supplemental appropriations bills to fund FEMA and other agencies’

disaster response programs.

A number of federal agencies have earthquake

mitigation research and implementation programs

that deal with specific earthquake risks faced by

these agencies. The Department of Veteran’s Affairs, the Department of Energy, the Department

of Defense, the National Aeronautics and Space

Administration, the National Oceanic and Atmospheric Administration, and others conduct a wide

range of earthquake-related research and mitigation (see appendix B).

Two recent executive orders address the earthquake risk in federal buildings. Executive Order

12699 (signed January 5, 1990) directs federal

agencies to incorporate seismic safety measures in

new federal buildings; Executive Order 12941

(signed December 1, 1994) establishes standards

21 Public Law 95-124, Oct. 7, 1977, as amended.

2242 LJ. S.C. 5121 er seq.
Chapter 1 Summary and Policy Options 113

100-

* 80- Current dollars

s

=

f 60-

0~.—

= 40-

1

Constant (1978) dollars

20

o~

1978 80 82 84 86 88 90 92 94

Fiscal year

SOURCE Office of Technology Assessment, 1995, based on NEHRP

budget data.

for use by federal agencies in evaluating and retrofitting existing federal buildings.

I Brief Description of NEHRP23

The National Earthquake Hazards Reduction Program was enacted on October 7, 1977, and has

been amended several times. The original law provided authorizations only for USGS and NSF.

Amendments in 1980 established FEMA as the

lead agency, and extended authorizations to

FEMA and to NIST. Amendments in 1990 clarified agency roles and set congressional reporting

requirements.

NEHRP actual spending has, in most years,

been considerably lower than that authorized (figure 1-3) and has decreased in constant (real) dollars (figure 1-4).

There is no NEHRP agency or central office.

Rather, NEHRP is a program in which four federal

agencies—USGS, NSF, FEMA, and NIST—par-

’23 See appendix A of his report for a detailed history of NEHRp.

ticipate. Almost two-thirds of NEHRP funds go

for earth science research—via USGS and NSF

earth science programs (see figure 1-5). Fourteen

percent is used for engineering research, and 21

percent is used by FEMA, mostly for implementation programs. (See figure 1-6 for data on how

agency funding has changed over time.)

U.S. Geological Survey

USGS accounts for about half of NEHRP funding—$49.9 million in fiscal year 1994. The majority of USGS activities related to earthquakes

are under the agency’s Earthquake Hazards Reduction Program, whose stated goals are:

■ understanding the earthquake source;

= determining earthquake potential;

■ predicting the effects of earthquakes: and

■ using research results .24

NSF

26.70/o

“’”JL ~ NIST

--’’’’” 2 0’

0

FEMA

20.8?40

KEY USGS = U S Geological Survey, NSF = National Science Foundation, FEMA = Federal Emergency Management Agency, NIST = Nat[on

al Institute of Standards and Technology

SOURCE Office of Technology Assessment, 1995, based on NEHRP

budget data

24 Ro~fi A. page et ~l., cOal~, oPPOrlU~iti~~, ~~d Priori[iesfor the USGS Earthquake Hazards Reduction Program. U.S. Geological Survey Circular 1079 (Washington, DC: U.S. Government Printing OffIce, 1992), pp. 1-2.
14 Reducing Earthquake Losses

100

90 

1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994

Fiscal year

KEY: USGS = U.S. Geological Survey, NSF= National Science Foundation, FEMA = Federal Emergency Management Agency, NIST = National Institute of Standards and Technology.

SOURCE: Office of Technology Assessment, 1995, based on NEHRP budget data.

More than two-thirds of its NEHRP funding is

used internally-to support USGS scientists in regional programs, laboratory and field activities,

national hazards assessment projects, and seismic

network operations. The remainder is spent as

grants to outside researchers for specific projects.

In general, the internal work focuses more on applying knowledge to describe hazards, while the

external program emphasizes expanding and

strengthening the base of scientific knowledge.

National Science Foundation

NSF accounts for about 27 percent of NEHRP

funding, 11 percent for earth science research and

16 percent for engineering research.

NSF awards grants directly to researchers for

the study of earthquake sources, active tectonics,

earthquake dating and paleoseismology, and shallow crustal seismicity.25 The program also supports a university consortium for seismological

research and a southern California earthquake research center. Instrument-based seismology, tectonics, and geodesy received the bulk of the

funding (together, about 90 percent) in recent

years; paleoseismology and microzonation efforts, in contrast, constituted about 5 percent of

the overall budget for individual awards.

The NSF earthquake engineering budget can be

divided into four major areas: support for the National Center for Earthquake Engineering Research (NCEER) in Buffalo, New York;

geotechnical research (e.g., liquefaction and soil

response); structural and mechanical research

(e.g., active control systems and design methodologies); and socioeconomic and planning research

(e.g., cross-cultural hazard response studies and

investigations of code enforcement).

25 James Whitecomb, Director, Geophysics Program, National Science Foundation, personal communication, NOV. 21, 1994.
Chapter 1 Summary and Policy Options 115

Area

Approximate

annual budget

(million $) Examples

Leadership

Design and construction standards

State and local hazards

reduction program

Education

Multihazard studies

Federal response

planning

1,3

5.0

6.1

1.1

1.7

0.9

User needs assessment.

Small-business outreach program

NEHRP plans, reports, and coordination.

Manual for single-family building construction.

Preparation of seismic design values.

Technical support for model codes.

Grants to states and cities for mitigation

programs,

Grants to multistate consortia.

Training in use of NEHRP provisions.

Dissemination of information on retrofit techniques.

Loss estimation software development.

Wind-resistant design techniques.

Urban search and rescue

National federal response.

SOURCE Federal Emergency Management Agency, Office of Earthquakes and Natural Hazards, “Funds Tracking Re

port, ” 1993

Federal Emergency Management Agency NIST’S funding under NEHRP has been relatively

FEMA is the lead agency of NEHRP and has re- low—less than $1 million annually until the

sponsibility for both overall coordination of the 1990s—s0 its NEHRP-related activities have

program and implementation of earthquake miti- been modest in size and scope. Current NEHRPgation measures. 26 FEMA’S activities in NEHRP related work is varied and includes: 27

are summarized in table 1-1. ●

National Institute of Standards ■

and Technology

NIST’s role in NEHRP has been largely in applied ●

engineering research and code development.

applied engineering research, such as testing of

building components;

technical support for model code adoption of

the NEHRP Recommended Provisions;28

technology transfer (support of conferences

and meetings for engineering research); and

26 This &SCrip[iOn of FEMA activities draws on Federal Emergency Management Agency, Buifdingjior /he Future, NEHRP Fy 1991-92

Report to Congress (Washington, DC: December 1992); Federal Emergency Management Agency, Preserving Resources Through Earthquake

Mifigarion, NEHRPFY 1993 -94 Report to Congress (Washington, DC: December 1994); and Federal Emergency Management Agency, Office

of Earthquakes and Natural Hazards, “Funds Tracking Report, FY 1993,” 1993.

27 Information drawn from Federa] Emergency M~agementAgency, preserving Resources Through Earthquake Mitigation, see footnote

26.

28 The recommended provisions are a resource document used by model Code develo~rs.
16 I Reducing Earthquake Losses

Engineering

Earth science Understanding the potential for great coastal earthquakes in the Pacific Northwest.

Ability to determine earthquake locations and magnitudes instantaneously.

Long-term, probabilistic forecasts of earthquakes for the San Francisco Bay region.

Instrumental recordings of liquefaction during strong ground shaking.

Availability of a strong-motion database.

Improved understanding of fault behavior and ground motion propagation.

Paleoseismology.

Understanding of the role of local soil conditions in influencing ground motion.

Improved techniques for nonlinear analysis of building components and structures.

Advances in analytical and modeling techniques that permit seismic structure design on

Inexpensive computers.

Improved understanding of how structures behave under earthquake-reduced stress—

leading to better building codes in areas such as bracing systems for steel structures.

Advances in new technologies, such as base Isolation and active control.

Better reliability and risk assessment techniques for lifelines and structures.

Improved disaster response planning from social science research that sheds light on, for

example, cultural differences in perceptions of disaster.

Implementation and NEHRP provisions adopted by model codes.

technology transfer Handbooks for seismic retrofits.

Information centers (information services at the National Center for Earthquake Engineering

Research at the State University of New York at Buffalo, the Earthquake Engineering Research Center at the University of California, and the Natural Hazards Center at the University of Colorado).

Executive orders covering new and existing federal buildings.

Multistate consortia.

SOURCES Robert A Page et al , Goals, Opportunities, and Priorities for the USGS Hazards Reduct/on Program, U.S. Geological Survey Circular

1079 (Washington, DC U S Government Printing Off Ice, 1992), p 5, and National Science Foundation, “Directions for Research in the Next Decade, ”

Report on a Workshop, June 1983

■ international cooperation (support of meetings

and exchange programs with other countries).

NEHRP CONTRIBUTIONS

AND CHALLENGES

❚ Contributions

NEHRP has led to significant advances in our

knowledge of both earth science and engineering aspects of earthquake risk reduction (see

table 1-2). For example, NEHRP has contributed

to the following accomplishments: the seismic

risk in the Pacific Northwest is better understood,

structures can be built that are unlikely to collapse

in an earthquake, and improved computer-based

structure design tools are available. Although

NEHRP is principally a research program, it has

contributed to the implementation of earthquake

mitigation as well. For example, we now have

model building codes that reflect a national consensus on new building seismic design, as well as

several interdisciplinary centers that work to

translate research results into useful information

for decisionmakers.

Despite these successes, however, earthquakes

still cause massive losses in the United States. The

1994 Northridge earthquake caused more than

$20 billion in losses, and scenarios of possible future U.S. earthquakes suggest that thousands of

casualties and tens or even hundreds of billions of
Chapter 1 Summary and Policy Options | 17

dollars in losses may occur. Although there is no

consensus on what level of loss is acceptable,29

there is clearly a significant remaining exposure to

earthquake damage—due in large part to a failure

to implement known technologies and practices.

Although many communities, especially in

California, have taken steps to mitigate earthquake losses, a large gap still exists between what

current knowledge says could be done and what

actually is done. Addressing this implementation gap is NEHRP’s greatest challenge.

❚ Implementation Gap

When NEHRP began in 1977, the enabling legislation contained a number of objectives, including

educating the public, ensuring the availability of

earthquake insurance, and promoting seismic

building codes and seismic considerations in

land-use policy. However, actual funding was authorized only for USGS and NSF, to be used for

earthquake-related research. Although in later

years some funding was authorized for implementation activities by FEMA, NEHRP has remained largely a research program. Currently,

about 75 percent of the NEHRP budget is used for

research.

This historical focus on research can be understood in part by recognizing that NEHRP was

founded at a time of great scientific optimism.

Newly discovered principles of plate tectonics

(see chapter 2) had led to great insights into earthquake mechanisms and many believed that shortterm earthquake prediction would soon become a

reality. This prediction capability was thought

sufficient to motivate widespread mitigation action. Therefore, NEHRP was given neither regulatory teeth nor significant financial incentives to

promote mitigation. Instead, the program aimed

to develop a body of knowledge from which local

and state authorities and the private sector would

draw. Since then, however, prediction has proved

more elusive than originally thought, and the original role of NEHRP as a source of knowledge from

which decisionmakers would eagerly draw is now

seen by many as insufficient, due to the lack of

regulations or incentives to implement the knowledge. This has contributed to the current situation

of an implementation gap.

Examples of this implementation gap include

the following:

 An assessment of California’s mitigation status

found, “we still have many earthquake-vulnerable buildings . . . it’s now possible to avoid

seismically hazardous areas and build earthquake-resistant structures, but too often the information needed is not used.”30

 Many states in moderate risk areas do not have

state seismic codes.31

 In those states that do have codes, many counties are not even aware of their existence.32

 Even when codes are adopted, they may not

cover all buildings—for example, they may exempt single-family dwellings.33

 A recent study concluded, “Even in California,

many localities consider seismic risks in only

the most rudimentary manner.”34

29 Although no losses would seem desirable, achieving this would be either impossible or impractically expensive.

30 California Seismic Safety Commission, California at Risk, 1994 Status Report, SSC 94-01 (Sacramento, CA:1994), p. 1.

31 R. Olshansky, “Earthquake Hazard Mitigation in the Central United States: A Progress Report,” in Proceedings of the Fifth U.S. National

Conference on Earthquake Engineering, July 10-14, 1994, Chicago IL (Oakland, CA : Earthquake Engineering Research Insitute, 1994), p.

991.

32Ibid.

33 The building code in Paducah, Kentucky, for example, exempts single-family dwellings; unanchored foundations are common. VSP

Associates, Inc., “State and Local Efforts To Reduce Earthquake Losses,” contractor report prepared for the Office of Technology Assessment,

December 1994, p. III-9.

34 P. Berke and T. Beatley, Planning for Earthquakes (Baltimore, MD: Johns Hopkins University Press, 1992).
18 I Reducing Earthquake Losses

The gap between knowledge (understanding) and

implementation can be daunting

If NEHRP continues along a similar path—

a focus on research, with a relatively small effort to promote implementation35—then we

will likely see advances in earthquake-related

earth science and engineering continue to outpace the implementation of new knowledge.

1 Additional Challenges

The implementation gap is a key issue for

NEHRP. However the program faces several additional challenges as well. These include a lack of

specific goals and strategies, differing expectations by different groups, tensions between basic

and applied research, and the inherent limitations

of NEHRP’s information-only approach to earthquake mitigation.

Goals and Strategies

In recent years, NEHRP has been criticized for its

lack of concrete goals and strategies:

■

■

■

A 1991 study found that, “federal agency descriptions of NEHRP. . . do not provide much

sense of an overall strategy.”sb

In hearings for the 1993 reauthorization. witnesses commented, “[NEHRP’s] fragmented,

four-agency structure has contributed to an inability to define program and budgetary priorities and achieve realistic, well-coordinated

goals.”37

A 1993 congressional report accompanying

NEHRP reauthorization legislation noted.

“long-standing concerns about NEHRP—[including] lack of an overall strategic plan.”~g

Although the NEHRP authorizing legislation

sets broad overall objectives for the program, actual NEHRP spending by the agencies involved

does not suggest any unified multiagency agreement on specific goals, strategies, or priorities. In

the absence of clear goals and strategies, each

agency’s NEHRP activities have evolved into a

portfolio that reflects that agency’s missions and

priorities, rather than strong multiagency agrecment. In addition, this lack of agreement on goals

and strategies makes judging the impact or success of the overall program difficult, since there

are few criteria by which to measure performance.

Differing Expectations

Different groups have different expectations from

NEHRP. In the absence of clear goals and strategies, these differing expectations make allocating

NEHRP’s scarce resources difficult.

The earth science research community is concerned with the state of knowledge of earthquakes. In its view, earthquakes arc a poot-ly

understood natural phenomenon. Thus, better understanding of earthquakes—why and how they

35 Cument]y NEHRP, through FEMA,does have some programs to promote implementation, but these are generally qultc small. For example, FEMA’s program to support state and local mitigation efforts is funded at about $6 million annually or, given 39 states that face a reasonable

seismic risk, at about $150,000 per state.

36 p. MaY, “Addressing ~b]ic Risks: Federal Earthquake policy Design,” Journal of Policy Analysis and A4anagemwt. vol. 10, No. 2, p.

270.

37 U.S. Congress, House Committee on Science, space, and T“ChmlOgy, Subcommittee on Science, hearing, Sept. 14, 1993. P 2~.

38 U.S. Congress, House Committee on Science, Space, and Technology, “Earthquake Hazards Reduction Act Reauthorization,” Nov. 15.

1993, p. 6.
Chapter 1 Summary and Policy Options | 19

occur, and when and what type of earthquakes are

likely to occur in the future—is an important component of reducing earthquake losses. This community would like NEHRP to be a source of

funding for research and data collection that

could, in the long term, help reduce such losses.

The engineering research community is concerned with how the built environment—buildings, bridges, dams, and so forth—is damaged in

earthquakes and how these structures should be

built so as to reduce losses. It sees the need for improvement in the current understanding of structural response to earthquakes, and considers

engineering research an important component of

reducing earthquake losses. Much like the earth

science research community, this group is concerned with the amount of funding NEHRP can

provide for research.

State and local government officials concerned

with earthquakes, in contrast, would like NEHRP

to provide products to help them reduce risk. State

highway agencies, for example, would like technical assistance in prioritizing and conducting retrofits of highway bridges. City planners would

like detailed maps showing liquefaction and landslide potential to help determine where and how to

guide development. Local code enforcement officials would like software to help determine code

compliance. Emergency managers would benefit

from methods to ensure that critical facilities

(such as hospitals and emergency communication

systems) survive earthquakes.

The practicing engineering and design community would like NEHRP to provide information on

the earthquake-related issues it faces: how to design safe buildings at low cost, what specific types

of ground motion to expect and when, and what

levels of retrofit protection to provide.

The public generally is unaware of or uninterested in NEHRP; however some individuals concerned with reducing earthquake risk have needs

that could be met by the program. Some large

companies and institutions have risk managers

whose responsibilities include earthquakes; these

individuals would like tools to help them reduce

risk, such as information on expected ground motion and likely damage, and methods for retrofit

prioritization. Electric and gas utilities would like

technical assistance in determining risk, and in

prioritizing and conducting retrofits. Some regions have community and grassroots groups concerned with earthquake risks; these groups would

like pamphlets, workbooks, and other material to

help inform the public. The media are often interested in information after an earthquake: how big

was the earthquake, where was the epicenter, and

what is the probability of significant aftershocks?

These different perspectives on NEHRP’s

function—each valid and sincere in its own right

—pull the program in different directions. These

pulls—between research versus implementation,

basic versus applied research, and earth science

versus engineering—complicate the allocation of

NEHRP’s finite resources, and can only be resolved through the setting of clear program goals.

Tensions Between Basic

and Applied Research

NEHRP currently supports a range of research,

from basic studies on how faults move to applied

work in testing building components. (See appendix B for a full description of NEHRP’s research

and development (R&D) portfolio.) Tension exists over the appropriate levels of support for these

different activities. Some argue that certain pressing short-term needs, if met, would yield significant social benefits. Others point out that basic

research is required to continue to advance the

knowledge base and that this work will not be

done without federal support.

It is useful to recognize that the distinction between “basic” and “applied” is better seen as a

continuum and that work at all levels is potentially

useful. In addition, across this continuum runs the

need for data collection, which can also demand

significant R&D resources.

Information Alone Has Its Limits

NEHRP’s approach to reducing earthquake losses

can be thought of as supplying information on

earthquake risks and possible countermeasures to

those who may wish to mitigate. By supplying

this information, the program hopes to motivate
20 | Reducing Earthquake Losses

individuals, organizations, and local and state

governments toward action while providing

guidelines on how to proceed. This approach implicitly assumes that the interest or incentive for

mitigation is sufficient for people to act on such

information. However, the frequent lack of mitigation activity often reflects not a lack of information, but a lack of interest or incentives to take

action. Information alone will not result in

widespread implementation. Whether or not the

federal government should play a role in ensuring

that there are sufficient incentives for implementation is a sensitive policy question that is discussed below. In any case, NEHRP’s approach of

supplying only information limits the program’s

impact.

POLICY OPTIONS

NEHRP reauthorization offers an opportunity for

Congress to consider what it wants to accomplish

with NEHRP and how it wishes the program to

proceed. A key decision is whether to maintain the

current federal role of research sponsor and information provider or to change the federal role

through, for example, changes in federal disaster

policy, insurance, or regulation. As discussed

above, NEHRP has had numerous research accomplishments and has made significant contributions to earthquake knowledge; it has

become clear that taking action based on this

knowledge is a key challenge for the future.

Significant changes in the federal role could potentially help close this knowledge-implementation gap. However, increasing the federal role

would be controversial. Furthermore, doing so

would represent a significant shift in NEHRP and

would require the participation of additional congressional committees.

Three types of policy options are discussed here:

1. Specific activities undertaken by NEHRP.

The Office of Technology Assessment (OTA)

identifies key research and implementation

needs that NEHRP could address within its current scope. Addressing these while maintaining

the current portfolio would require increased

funding.

2. Management and operational changes in

NEHRP. These could allow NEHRP to be a

more efficient, coordinated, and productive

program.

3. Changes to federal disaster assistance and

insurance, regulation, and financial incentives. These would be necessary if Congress

decides that the federal government should take

greater responsibility for the implementation

of NEHRP-produced knowledge. They are outside the current scope of NEHRP and would

represent a significant change in direction for

the program.

❚ NEHRP Portfolio Changes

NEHRP currently supports earth science research,

engineering research, and implementation support and promotion. In each of these areas OTA

has identified specific topics needing further

attention.

Earth Science Research

Earth science research can help to reduce earthquake-caused deaths, injuries, and other losses by:

 narrowing the uncertainty of when and where

large earthquakes will occur;

 estimating, as accurately as possible, the expected ground motions, ground failure, and

other effects that will occur in future earthquakes; and

 developing maps of these seismic hazards for

use by engineers, land-use planners, and emergency managers.

Historically, NEHRP has focused on basic

research that contributes primarily to the first

objective and, to a much lesser degree, on disseminating research results to the public. In large

part, this is due to the absence of clear goals or

strategies for the program, an issue discussed in

greater detail in a following section. Without consensus on programmatic goals, NEHRP’s earth

science R&D portfolio has been strongly influenced by the values and concerns of the agencies supporting it—NSF and USGS—both of

which have strong research orientations. Basic research into fundamental earth processes (e.g., how
-. — ..- . Chapter 1 Summary and Policy Options 121

do earthquakes begin and propagate) dominates

the research supported by NSF under NEHRP.

USGS supports research that is generally more applied than that of NSF (e.g., developing and distributing detailed maps showing expected ground

motions), but conducts and sponsors some basic

research as well. With NEHRP funding, NSF and

USGS also support seismic monitoring networks

and other data collection efforts related to earthquake research and seismic hazard assessment.

If Congress views NEHRP’s earth science activities as primarily a means of providing long-term

benefits (e.g., enhancing fundamental understanding of earth processes such that uncertainties

in the timing, location, and magnitude of future

earthquakes can be reduced), retaining the current

concentration in more basic research would be appropriate. This work has yielded new insight into,

for example, the relationship between plate deformation and earthquakes, the mechanics of fault

rupture, and the sources of some intraplate

quakes. In time, this research may narrow the uncertainties in future earthquake location, timing,

and effects.

Today, however, knowledge of seismic hazards

in many U.S. metropolitan areas remains very

limited. Outside of coastal California and a few

other cities (e.g., Salt Lake City, Memphis, Portland, and Seattle), assessing and mapping earthquake hazards is proceeding very slowly. If

Congress believes that NEHRP should now place

more emphasis on near-term applications of data

and research results to risk assessment (e.g., microzonation), then NEHRP’s earth science portfolio should include a greater share of activities that

meet these goals.

Engineering Research

Knowledge of how to design and build structures

to reduce earthquake-induced losses has improved tremendously. However the problem is far

from solved. The 1994 Northridge earthquake ocTsunamis are an infrequent but dangerous result of undersea

earthquakes.

Tsunam/s can cause major damage.

curred in the area of the United States that is probably the most well prepared; nevertheless, the

quake caused dozens of deaths and more than $20

billion in losses. Scenarios of future earthquakes

suggest that large losses are likely.

Greater use of existing knowledge, practices,

and technologies could reduce these losses. For

example, the collapse of the 1-880 elevated highway in the 1989 Loma Prieta earthquake, which

caused the deaths of 42 people, could have been

prevented with the use of known retrofit technologies.sg The impkmtmtation (or lack thereof) of

these technologies to date has been determined

~~ u s. . Congress, Genera] Accounting office, “Loma Prieta Earthquake: Collapse of the Bay Bridge ~d tie Cypress Viaduct,” GA@

RCED-90- 177, June 1990, p. 2.
22 I Reducing Earthquake Losses

Many older buildings are vulnerable to structural collapse.

largely by economic, behavioral, institutional,

and other factors—not by the state of current

knowledge.

Nevertheless, additional. knowledge could

have several benefits. First, although our understanding of how to build new structures to resist

seismic damage is good, it is far from perfect (e.g.,

the steel weld failures in modem buildings in the

Northridge earthquake, discussed in chapter 3).

Second, most of the financial losses in recent

earthquakes were not due to building collapse.

Rather, they resulted from structural, nonstructural, and contents damage—areas that could benefit

from further research. Third, much of the casualty

risk lies in existing structures, and retrofit methods are just now being refined and standardized.

More research into improving retrofits could reduce this risk. Fourth, to the extent that the upfront

costs of mitigation reduce implementation, research that reduces these costs could lead to greater implementation.

New buildings

A new building that meets current seismic building codes will be very resistant to collapse due to

earthquakes. This is a great technical accomplishment in which NEHRP played a considerable role.

Since this has been achieved, it is time to consider

moving some resources to the next research challenge: reducing structural, nonstructural, and

contents damage. Possible areas of research include:

m data collection and analysis of structural, nonstructural, and contents damage from recent

earthquakes;

analytical methods to measure and predict such

damage;

guidelines for designing lighting, electrical,

water, and other systems so as to minimize seismic damage;

building codes that address structural, nonstructural, and contents damage; and

new technologies—notably active and passive

control (see chapter 3)—that can reduce this

damage.

Existing buildings

Much of the risk of both structural collapse and

nonstructural and contents damage lies in existing

buildings, which do not incorporate current codes

and knowledge. Relatively few of these buildings

have been retrofitted to reduce risk, and where retrofits have been performed they have often been

expensive, complex, and of uncertain benefit. Although NEHRP has made progress in understanding and improving retrofits (e.g., through FEMA’s

existing buildings program), more research is

needed to improve retrofit methods.

The first area of research for existing buildings should be to better understand their vulnerability. Laboratory and field experiments, and

collection and analysis of data on how buildings

respond in earthquakes, are needed. Improved

tools to determine risk in existing buildings—

such as nondestructive evaluation techniques—

are needed as well. A second area is the

development of low-cost standardized retrofit

techniques. Standardized methods, such as those

contained in codes for new construction, would

reduce costs and could allow for multiple levels of

safety to account for different risk preferences. A

third research area is to extend retrofits to nonstructural and contents damage reduction.
Chapter 1 Summary and Policy Options | 23

Lifelines

Lifelines are expensive to repair, and service interruptions, which are at best inconvenient and at

times deadly, may result in large economic losses.

The lack of an accepted national standard for the

design and construction of lifelines raises costs

and reduces performance. Although the 1990

NEHRP reauthorization directed that FEMA and

NIST work together to develop a plan for developing and adopting design and construction standards for lifelines by June 30, 1992, as of May

1995 no such plan had been submitted to Congress.

Much of the life safety risk associated with lifelines lies in existing facilities. Research is needed

to develop methods to better determine the risks in

existing facilities, to prioritize retrofits, and to reduce retrofit costs. Low-cost, easy-to-use procedures to analyze lifelines for weak links would

help to ensure their continued function in earthquakes.

Implementation of Mitigation

NEHRP supports mitigation several ways:

through technical support of state and local efforts, through research to better understand the

implementation process, and through knowledge

transfer efforts. Some promising directions that

could improve these activities are discussed below.

Perhaps the most promising implementation

activity is to directly assist communities in their

efforts to understand earthquake risk and to devise

mitigation options. In particular, it is critical that

communities be given analytic tools to estimate

likely losses in the event of a future earthquake

and to predict the likely benefits of mitigation.

At present, it is difficult to quantify these basic parameters, and this absence inhibits vigorous action at all mitigation levels. Fortunately recent

advances in computers—and specifically in geographical information systems—suggest that it

will soon be possible to provide local decisionmakers with highly detailed and specific information on seismic risks, even on a specific building

level. FEMA is now supporting an effort to make

these regional loss estimation tools available to

local governments. This is a promising direction

that could reduce considerably the uncertainty in

risk. These tools often require large amounts of

detailed data on local land-use patterns and building stock; communities need help in defining data

needs and collecting data as well. User training

may also be needed.

Better evaluation of FEMA implementation

programs is needed. Very few of these programs

have been evaluated carefully in the past, leaving

current program planners with little guidance as to

what works, what does not work, and why. All

mitigation programs should be evaluated carefully, and the results should be used to improve, refocus, or—if necessary—terminate programs.

Because individual local “advocates” can play

a powerful role in fostering and maintaining community interest in mitigation, efforts to create or

assist advocates are potentially quite useful. The

federal government can support advocates by

identifying and working closely with them to ensure their access to the latest mitigation information and analysis tools.

Media and public outreach activities can have a

powerful indirect effect. The more publicity there

is concerning earthquakes, the more likely that advocates will arise and act. Public interest in earthquakes largely depends on how recently a major

quake last occurred, so preparing outreach materials to take advantage of disaster “windows” is a

prudent measure. The advantage of this outreach

is that it is relatively inexpensive and can be very

effective.40

To complement activities on the seismic front,

efforts could be made to incorporate seismic implementation into a larger “all-hazards” framework. Much of the nonstructural preparation

40 The disadvantage is that in places where destructive seismic activity is extremely infrequent (e.g., the U.S. east coast), these windows are

rarely open.
24 I Reducing Earthquake Losses

THE FAR SIDE By GARY LARSON

Some areas of the US. are threatened by a variety of natural

hazards. (The Far Side cartoon by Gary Larson is reprinted

by permission of Chronicle Features, San Francisco, CA. All

rights reserved).

required for seismic mitigation (e.g., predisaster

emergency planning) is useful in the event of fire,

flood, wind storm, or other natural disasters, and

can thus gain in political and economic attractiveness when viewed in a larger context.

In addition to direct support for implementation, NEHRP also supports some research into the

behavioral, social, and economic aspects of mitigation. Further research of this type could improve our understanding of some key questions

that currently hinder mitigation. Examples of specific questions that NEHRP could address include

the following:

❑ How do financial and other incentives affect

mitigation behavior? To what extent is insurance and the expectation of federal disaster relief currently a disincentive for mitigation?

How is NEHRP-generated information (e.g.,

hazard maps and building seismic response

data) used by the mitigation community? How

should this information be presented to ensure

its appropriate and productive use?

How well have NEHRP-supported information

and technology transfer efforts worked? What

contributed to their successes and failures, and

what does this suggest for future efforts?

The answers to these questions could help improve the next generation of NEHRP-supported

implementation programs.

The four NEHRP agencies have put increasing

effort into “knowledge transfer”—institutions

and procedures that promote the delivery of useful

information to decisionmakers. For example,

NEHRP funds several “centers” that emphasize

matching research to user needs and ensuring research results are provided in a useful form to decisionmakers. NEHRP also supports several

information services that provide research results

to interested users, as well as multistate consortia

that coordinate state activities and facilitate communication between researchers and users.

The implementation gap discussed above suggests that these efforts be continued and expanded. Options for expansion include increasing

funding for knowledge transfer programs, requiring utilization plans for applied research projects,

and establishing formal utilization criteria for

evaluating applied research proposals.41 All such

efforts should be evaluated carefully and regularly.

Allocating NEHRP Funding

Current NEHRP funding is about $100 million

annually. The ideal method to determine appropriate funding levels would be to consider the costs

and benefits of future NEHRP spending. Although the direct costs are clear—simply the pro41 A detailed discussion of options for increasing the use of applied research can be found in Applied Technology Council, Enhancing the

Transfer of USGS Research Results into Engineering Practice, ATC-35 (Redwood City, CA: 1994).
Chapter 1 Summary and Policy Options | 25

jected funding—the benefits are not. Much of

NEHRP funding is for research, and the results of

research—greater understanding—are not easily

quantified. NEHRP’s spending for implementation should be somewhat easier to evaluate. However, as noted above, past implementation

programs have not been evaluated in a systematic

way; thus there is little guidance on the likely

benefits of future spending. Improved evaluation would provide guidance for deciding

funding levels and allocations.

NEHRP spending, both in allocation and in total, should reflect national priorities. Basic conceptual earth science research enhances our

understanding and will likely, in the long term,

translate into better mitigation. Engineering research can produce more immediate benefits. Implementation programs, such as FEMA’s state and

local grants, can have immediate impacts. The

current NEHRP portfolio is tilted strongly toward

earth science research: 64 percent of NEHRP

spending is under USGS and NSF earth science. If

Congress would like NEHRP to emphasize improving basic knowledge, and thus provide longer

term societal benefits, then the present mix is appropriate. If, however, Congress would like

NEHRP to produce more immediate societal risk

reduction, then a tilt toward engineering and implementation would be appropriate.

❚ Structural and Operational Changes

Policy options related to the structure and operations of NEHRP include changes to improve program coordination, changes in the lead agency,

and improvements in cross-agency coordination.

Program Coordination

Overall program coordination and the selection

and role of the lead agency in NEHRP have been

problematic since the program began.42 Initial

NEHRP legislation directed the President to select a lead agency, and the 1980 reauthorization

designated FEMA as the lead agency. Since then,

evaluations of and hearings on NEHRP have often

criticized FEMA’s management and coordination

of the program. Examples of this criticism include:

 a 1983 General Accounting Office report that

noted, “FEMA needs to provide stronger guidance and direction”;43

 the Senate report accompanying the 1990 reauthorization that noted, “the need to improve

coordination of the agencies in the program”;44

 hearings for the 1993 reauthorization in which

witnesses commented on, “the diffusion of responsibility inherent in four different federal

agencies attempting to implement NEHRP”; 45

 a 1993 congressional report that noted, “insufficient coordination among the [NEHRP] agencies to shape a unified, coherent program.”46

Coordination is difficult to measure. OTA’s

meetings and discussions with NEHRP agencies,

and its reviews of NEHRP activities, did not uncover any glaring examples of poor coordination.

NEHRP staff in each agency were aware of activities in other agencies; they had frequent informal

contact with each other and made efforts to keep

one another informed of changes and findings.

FEMA has produced congressionally mandated

42 See David W. Cheney, Congressional Research Service, “The National Earthquake Hazard Reduction Program,” 89-473 SPR, Aug. 9,

1989; U.S. Congress, General Accounting Office, “Stronger Direction Needed for the National Earthquake Program,” GAO/RCED-83-103,

July 1983; and VSP Associates Inc., “To Save Lives and Protect Property,” Report for the Federal Emergency Management Agency,

FEMA-181, July 1989.

43 General Accounting Office, see footnote 42, p. 7.

44 U.S. Congress, Senate Committee on Commerce, Science, and Transportation, National Earthquake Hazards Reduction Program Reauthorization Act, Report 101-446, (Washington, DC: Aug. 9, 1990), p. 3.

45 House Subcommittee on Science, see footnote 37.

46 House Committee on Science, Space, and Technology, “Earthquake Hazards Reduction Act Reauthorization,” see footnote 38.
26 | Reducing Earthquake Losses

reports and plans that describe the NEHRP programs in detail.

As discussed above, however, actual NEHRP

spending by the agencies does not suggest any

overall multiagency agreement on specific goals,

strategies, or priorities, but suggests instead a

loosely coordinated confederation of agencies. In

the absence of clear goals and strategies, each

agency’s NEHRP activities reflect that

agency’s missions and priorities rather than a

strong multiagency agreement. This lack of

agreement on goals and strategies also makes it

difficult to judge the impact or success of the overall program, because there are no criteria by which

to measure performance. In OTA’s view, coordination must be preceded by agreement on

specific goals and priorities—and such agreement is largely lacking.

One policy option is for FEMA, as lead agency,

to work with the NEHRP agencies and the professional earthquake community to come up with

specific goals and priorities for NEHRP. An example of such a goal is to have 80 percent of new

building construction incorporate the seismic

knowledge represented in today’s model codes by

2005. Defining such goals would not be easy and

would have to address the difficult issue of acceptable risk. Congress could require FEMA to report

on progress toward defining and meeting these

goals. Since FEMA has no explicit budgetary or

other control over the other agencies that participate in NEHRP, Congress may wish to provide

oversight to ensure that all these agencies work toward defining and meeting the agreed-on goals.

The Lead Agency

The continuing congressional dissatisfaction with

FEMA’s management and coordination of

NEHRP has led some to consider transferring lead

agency responsibility from FEMA to another

agency. OTA’s finding that implementation is

emerging as NEHRP’s key challenge, however,

suggests that, of the four principal NEHRP agencies, FEMA appears to be the most appropriate

lead agency. FEMA has the most direct responsibility for reducing losses from natural disasters; it

is in direct contact with state, local, and private

sector groups responsible for reducing earthquake

risks; it has a management rather than research

mission; and it coordinates regularly with other

agencies in carrying out its mission. The other

NEHRP agencies are principally involved in research and, therefore, may find it difficult to develop the strong implementation component

necessary to lead the program. In addition, FEMA

has recently shown a stronger commitment to mitigation, as evidenced by its proposed National

Mitigation Strategy.47 One policy option would

be to allow FEMA to continue as lead agency, but

to provide frequent oversight to ensure that lead

agency responsibilities are met.

Coordinating with Non-NEHRP Agencies

Although NEHRP is the government’s central

earthquake program, a significant fraction of federal spending on earthquake mitigation occurs not

within the four NEHRP agencies, but in other

agencies that both sponsor research and implement earthquake mitigation. The Department of

Veterans Affairs, the Department of Energy, the

Department of Defense, the National Aeronautics

and Space Administration, the National Oceanic

and Atmospheric Administration, and other federal agencies conduct a wide range of earthquake-related research and mitigation (see appendix B).

Although there is no unified federal earthquake

budget, federal non-NEHRP earthquake spending

probably far exceeds the $100 million NEHRP

budget.48 Despite this wealth of activity, there are

few formal structures for coordinating non47 The National Mitigation Strategy, under development by FEMA, is an effort to increase attention on mitigation as a means to decrease

demand for disaster response resources.

48 The last budget data were for the period ending in 1987. Cheney, see footnote 42, p. 20.
Chapter 1 Summary and Policy Options | 27

NEHRP federal efforts.49 Improved coordination

across all agencies would be useful. For example,

it could allow one agency to serve as a demonstration site for a technology developed with NSF

funding, or enable agencies to share data on

ground motion or retrofit techniques.

Ensuring multiagency coordination is challenging. The first step in doing so could be to promote a thoughtful combination of improved

information sharing and incentives for coordination. Examples might include:

 establishing a “Federal Agency Earthquake

Activities” home page on the Internet, hosted

by FEMA;

 sharing employees across agencies (e.g., a

NIST seismic design researcher could spend

one month as a “visiting scholar” to assist the

Department of Veterans’ Affairs in retrofitting

hospitals); and

 encouraging agencies implementing seismic

technologies to communicate with NSF- and

NIST-funded researchers working on these

technologies, to ensure their appropriate use or

to demonstrate new and innovative approaches.

More aggressive actions to ensure multiagency

coordination include:

 requiring the NEHRP lead agency to maintain

a database with information on all federal

agency earthquake-related activities, and to

make this database available electronically to

agencies and to state and local governments;

 requiring all agencies with earthquake activities to participate in the goal-setting process

proposed above; or

 requiring the submission of an annual budget

laying out all earthquake-related agency activities.

❚ Beyond the Current NEHRP

Congress could consider other policy options that

are outside the scope of NEHRP as currently designed. This section discusses three areas in which

policy change could be considered: insurance and

federal disaster relief, regulation, and incentives.50 The policy options discussed here have

the potential to significantly increase implementation—something NEHRP, in its current

form, is unlikely to accomplish. However, these

options would likely require new legislation and

would be a significant departure from current

policy. They would also be quite controversial.

In considering these options, a central issue is

what is the appropriate role of the federal government in disaster mitigation? Some argue that

increased investment in mitigation by the federal

government would save money by reducing future

disaster outlays. Others argue that the very existence of federal disaster assistance programs

creates disincentives for mitigation. Still others

argue that mitigation tools, notably land-use planning and building regulation, are state and local issues in which an increased federal role is

inappropriate. These arguments involve different

political and philosophical beliefs. OTA does not

attempt to resolve them.

Insurance and Federal Disaster Assistance

The issue of insurance and federal disaster assistance—and specifically, what role, if any, the federal government should play in earthquake

insurance (or natural hazards insurance in general)—is complex and contentious. Several bills to

set up a comprehensive federal disaster insurance

program were introduced in the 103d Congress

(none were passed), and others have been or are

49 Many federal agencies participate in a multiagency group known as the Interagency Committee on Seismic Safety in Construction, set up

to establish and implement standards for federal construction and retrofit. Some agencies also participate in the Subcommittee on Natural Disaster Reduction, under the National Science and Technology Council.

50 Much of this section applies to federal policy toward other natural disasters as well, such as floods, hurricanes, and tornadoes.
28 | Reducing Earthquake Losses

expected to be introduced in the 104th Congress.

Other bills propose changes in federal disaster assistance; for example, one bill proposes giving

states financial responsibility for natural disasters. Congressional interest in disaster insurance

is motivated largely by the recent string of natural

disasters in the United States, and the fact that, in

fiscal years 1992 to 1994, Congress passed $10.8

billion in supplemental appropriations for natural

disasters.51

Among the issues involved in this debate are:

 Equity. Is it “fair” for natural disaster losses to

be covered by the U.S. Treasury? To what extent should those at risk pay for their own

losses? Should the federal government pay for

the noninsured and underinsured? Should natural disaster insurance be required for those at

risk?

 Insurance industry financial health. Can the

insurance industry survive a series of large disasters? Should the federal government have a

formal mechanism to provide secondary insurance to the industry?

 Mitigation. What is the relationship between

insurance or disaster assistance and mitigation?

 Appropriate roles. What are the appropriate

roles of the federal government, state regulators, and the private insurance industry in natural disaster funding?

The following discussion focuses on the relationship between insurance or disaster assistance

and mitigation. Readers interested in other aspects

of insurance are referred elsewhere.52

Insurance and disaster assistance can be a vehicle for mitigation, as well as a disincentive

against mitigation, depending on how the program is structured. At its simplest, an insurance

program—whether private or public—can simply

require mitigation as a condition of insurance. For

example, the federally subsidized national flood

insurance program requires, as a condition of receiving insurance coverage, that the lowest floor

of a new structure be above the base flood level.53

In the case of earthquakes, insurance might require a basic level of seismic safety, or might not

be offered for structures built in high-risk areas

such as landslide-prone hills. This approach is

complicated by the fact that relatively few residences are covered by earthquake insurance; requiring mitigation would most likely further

reduce this number. One solution is a mandatory

insurance program, where owners of structures at

risk are required to purchase insurance. Structures

in high-hazard flood areas, for example, are required to have insurance if federal loans or grants

were involved in building or buying the structure.54

Insurance can also promote mitigation by having rates reflect risk.55 Much as drivers who have

had accidents pay more for automobile insurance,

structures that are located in high-risk areas or that

do not incorporate accepted seismic design principles can be charged more (or be subject to higher

deductibles or lower coverage limits) for earthquake insurance. This approach is limited by the

fact that earthquake insurance is voluntary and

51 For comparison, the total supplemental appropriations from 1974 to 1991 was $4.4 billion. U.S. Congress, Congressional Research Service, “FEMA and Disaster Relief,” 95-378 GOV, Mar. 6, 1995, p. 10.

52 See, e.g., U.S. Congress, Congressional Research Service, “Natural Hazard Risk and Insurance: The Policy Issues,” 94-542E, July 5,

1994; U. S. Congress, Congressional Budget Office, “The Economic Impact of a Solvency Crisis in the Insurance Industry,” April 1994; Federal

Emergency Management Agency and Department of the Treasury, “Administration Policy Paper: Natural Disaster Insurance and Related Issues,” Feb. 16, 1995.

53 The base flood level is the elevation at which there is a 1 percent chance of flooding in a given year. U.S. Congress, General Accounting

Office, “Flood Insurance: Financial Resources May Not Be Sufficient To Meet Future Expected Losses,” GAO/RCED-94-80, March 1994, p.

11.

54 Ibid.

55 Earthquake risk is often very uncertain. Development of risk estimation tools as discussed above would be helpful in setting insurance

rates as well.
Chapter 1 Summary and Policy Options | 29

often not purchased. Large rate increases would

presumably further decrease the number of structures (especially high-risk ones) covered by earthquake insurance. Again, making earthquake

insurance mandatory would address this, but it

raises fundamental questions about individual responsibility and the role of government.

Insurance can work against mitigation as well.

In our present system, most structures do not have

earthquake insurance. In recent earthquakes,

losses have been covered in part from the U.S.

Treasury via supplemental appropriations. This

can be considered a form of insurance in which the

premiums are the federal taxes paid by all. In this

form of insurance, there is no relationship between premiums and risk. Similarly, insurance in

which there is no connection between either premiums, or the availability of insurance, and risk

can work against mitigation through what is

known as “moral hazard.” In this situation, appropriate mitigation measures are not taken because of the belief that insurance will cover losses

in any case.

The issue of moral hazard is especially relevant

to earthquakes. One commonly held belief is that

current federal disaster policy is a disincentive for

property owners to purchase private earthquake

insurance. If one believes that the federal government will cover one’s losses in the event of an

earthquake, then in theory it would not be economically rational to pay for private insurance.

This argument is sometimes used to explain the

surprisingly low fraction of California homeowners who purchase earthquake insurance—currently about 25 percent.56

Evidence from surveys, however, suggests that

the relationship between mitigation and expected

federal aid is somewhat more tenuous than commonly thought:

Most homeowners said they do not anticipate

turning to the federal government for aid should

they suffer losses . . . we hypothesize that most

homeowners in hazard-prone areas have not

even considered how they would recover should

they suffer flood or earthquake damage . . . the

(survey) results suggest the people refuse to attend to or worry about events whose probability

is below some threshold.57

This evidence suggests that the low rate of insurance ownership in California could be explained

in part by a general lack of interest in low-probability events such as earthquakes, not simply by

the expectation of federal aid.58

Congressional decisions as to the fate of hazard

insurance legislation will involve many issues,

most of which are beyond the scope of this report.

With respect to mitigation, however, clearly insurance can be a strong incentive for earthquake mitigation—if the cost of insurance

reflects the risk. In addition, social science research suggests that individual mitigation decisions are not made on an economically rational

cost-benefit basis but are considerably more complex. Federal insurance programs should recognize these complexities.

56H. Kunreuther et al., “On Shaky Ground?” Risk Management, May 1993, p. 40.

57 H. Kunreuther, Disaster Insurance Protection (New York, NY: John Wiley and Sons, 1978), pp. 236-238. More recently, “There is little

empirical evidence suggesting that individuals are not interested in insurance because they expect liberal disaster relief following a disaster.” H.

Kunreuther, “The Role of Insurance and Regulations in Reducing Losses Hurricanes and Other Natural Disasters,” Journal of Risk and Uncertainty, forthcoming.

58 Some argue that high premium costs and high deductibles contribute to the low levels of insurance ownership as well. Earthquake premiums in California prior to the Northridge earthquake were typically $2 per $1,000 of coverage per year, with a 10 percent deductible. U. S.

Congress, Congressional Research Service, “A Descriptive Analysis of Federal Relief, Insurance, and Loss Reduction Programs for Natural

Hazards,” 94-195 ENR, Mar. 1, 1994, p. 106.
30 | Reducing Earthquake Losses

Regulation

A key challenge to earthquake mitigation is its

voluntary nature: people are often unwilling to invest time and money to prevent unknown, uncertain, or unlikely future damage. NEHRP relies

mostly on a supply-side approach to mitigation: it

makes available information and technical expertise, and leaves the decision of adoption to the

state, local government, or individual.

One policy area, largely outside the scope of

NEHRP as currently defined, would be for the

federal government to take a stronger position on

implementation via regulation. In the current

policy environment, regulation in the form of

building codes is the most widely used mitigation

tool, but it is performed at the state or local level.

The federal government plays largely an indirect

role by providing technical support for code development and implementation. A more aggressive policy option would be to require states and

localities, as a condition for receiving federal aid,

to adopt model building codes or demonstrate a

minimum level of code enforcement. Nonstructural mitigation could be advanced through an

executive order addressing this problem in federal

buildings.

Arguments in favor of increasing the federal

role in requiring the use of seismic mitigation

measures include:

 The federal government pays much of the costs

of seismic losses through disaster relief; it

would be economical to require some reasonable level of mitigation.

 The information and behavioral barriers to mitigation are great. It may be less expensive to

regulate than to attempt to overcome these barriers with public information or incentive programs.

 There are many precedents for regulations to

protect public safety and property. Examples

include safety and performance requirements

for consumer goods (e.g., seat belts and bumpers for cars) and safety standards for services

(e.g., safety training for airline pilots and flammability limits for airplane cabins).

 Regulation is usually simpler and less expensive (in terms of direct government outlays)

than most other policy options (e.g., R&D, financial incentives, or improved consumer information).

 The losses resulting from a damaged or destroyed structure can be considered an externality (defined as a cost to society not captured in

the market price of a good), because some costs

are paid by society as a whole through disaster

assistance programs. As such, the price of

structures should be raised to a level reflecting

their true cost to society. (Strictly speaking, this

is an argument for market intervention, not necessarily for regulation.)

There are, as well, a number of arguments

against increasing the federal role in requiring the

use of seismic mitigation measures, including:

 Regulation of buildings and construction is

currently a state and local issue, not a federal

one. Any federal role beyond that of providing

information could be considered an infringement on state and local rights.

 Current levels of mitigation reflect individual

and market preferences. Regulation would impose costs and investments that would otherwise not be made.

 The inherent inflexibility of regulations may

result in mitigation investments that increase

net societal costs.59

 Regulation is not a cure-all—many individual

mitigation actions, such as not putting heavy

books on the top of bookshelves, cannot realistically be regulated.

Evaluation of these arguments is a political,

not a technical, decision. If Congress does decide

59 Not all mitigation is financially prudent (an extreme example might be requiring a building used exclusively for storage to provide a high

level of life safety).
Chapter 1 Summary and Policy Options | 31

to pursue a regulatory approach, then a much better understanding of the costs and benefits of mitigation would be needed to set these regulations at

an appropriate level.

Financial Incentives

NEHRP currently relies on information, along

with a modest amount of technical support, to promote mitigation. A policy direction that, like regulation, is outside the scope of the current

NEHRP, would be the use of financial incentives

to promote mitigation. These could take the form

of rewards for greater mitigation (e.g., tax credits

or low-interest loans) or punishments for insufficient mitigation (e.g., taxing buildings not meeting code, or reducing disaster assistance to those

who did not mitigate).

Among the advantages of such an approach

are:

 It retains some flexibility and freedom of

choice, since participation is voluntary.

 It can be structured so as to require no net federal spending (e.g., by using a combination of

taxes and grants).

 As mentioned above, as long as the public pays

for disaster relief, the losses resulting from a

collapsed structure can be considered an externality (i.e., a cost to society that is not captured in the market price of a good). As such,

the price should be raised to a level reflecting

the true cost.

Disadvantages include:

 The administrative costs of such a system could

be high.

 The response of the market to financial incentives is not well known; it may be that very

large subsidies (or penalties) are needed to

change behavior.

 As with regulation, the benefits of mitigation

are often difficult to quantify. Thus, incentives

for increased mitigation may mean more

money poorly spent.

A decision as to what, if any, financial incentive

should be used to promote mitigation is, like the

decision to regulate, largely a political and not a

technical decision. Financial incentives can promote mitigation. However, the behavioral response to such incentives is not well understood.

Thus, such incentive programs should be thought

out carefully and tested on a pilot scale before fullscale implementation.
Understanding

 Seismic

 Hazards

arthquakes remind us that the earth is continually changing, sometimes with disastrous consequences for its inhabitants and for the relatively fragile structures built atop

its outermost layer. Our understanding of the seismic hazard (i.e., the potential for earthquakes and related effects) has improved significantly in the last two decades, largely through

research supported by the National Earthquake Hazards Reduction Program (NEHRP). This improved knowledge of the seismic

hazard can in turn be applied to better estimation of the potential

impact on specific communities. For example, earthquake-related research and development (R&D) to date has yielded detailed information on historical and estimated future ground

motions that earthquake engineers now use for research, design,

and building code development.

Federal support for earthquake-related R&D in the earth

sciences is concentrated in programs directed by both the National Science Foundation and the U.S. Geological Survey (USGS)

under the aegis of NEHRP; other federal agencies conduct related

research as well (see appendix B). Since focused efforts began,

there have been many achievements in earth sciences. However,

the complexity of the task of understanding earthquake phenomena means that significant uncertainties remain about the timing

and location of future damaging earthquakes and the exact nature

of their effects.

This chapter reviews the current knowledge of earthquake phenomena and of seismic hazards across the United States. It then

outlines the role of basic and applied earth science R&D in meeting information needs for the nation’s earthquake loss mitigation

program, and provides examples of research efforts needed to address knowledge gaps. | 33
34 | Reducing Earthquake Losses

EARTHQUAKES

An “earthquake” technically refers to trembling or

strong ground shaking caused by the passage of

seismic waves through the earth’s rocky interior.

These waves arise from phenomena as varied as

explosions,1 volcanic eruptions, or quarry blasts,

but the source most commonly associated with the

term is the fracturing, or faulting, of rocks deep

underground through the action of powerful geologic forces.

Seismic waves radiate away from a rupturing

fault in the same way that ripples in a pond spread

outward from a splashing pebble. These waves die

away with distance from the initial source, so that

very distant or very deep earthquakes are of relatively little concern. Like pond ripples, the waves

can bounce and bend around obstacles to produce

intricate patterns. Because the structure of the

earth is far more complicated than the surface of a

pond, what happens when seismic waves reach the

earth’s surface can be exceedingly complex.

Efforts to assess risks to U.S. communities

posed by future earthquakes rest on the ability to

estimate where and when earthquakes will occur

and to quantify, where possible, what will happen

when earthquake-generated seismic waves hit the

earth’s surface. (Figure 2-1 illustrates seismicity

that has occurred in the United States.) Specific

questions addressed by current earth science research include:

 What causes a particular fault to rupture?

 How do seismic waves propagate through the

earth?

 How do seismic waves and local geology interact to produce strong ground motions2 or damage to the earth’s surface?

Two distinct methods of evaluating the severity

of an earthquake are: 1) calculating its magnitude,

and 2) estimating its intensity. The magnitude of

an earthquake is related to the amount of seismic

energy released at the quake’s source; it is based

on the amplitude of the seismic waves recorded on

seismographs. Earthquake magnitude calculations also take into account the effects of distance

between the recording instrument and the source

of the waves, and the type of instrument itself.3

The magnitude scale most widely used for

many years is the Richter magnitude scale,

introduced in 1935 by Charles Richter and Beno

Gutenberg. A strong earthquake, for example,

would have a Richter magnitude (M) of 6.0 to 7.0,

while a great earthquake such as the 1906 earthquake beneath San Francisco would measure

above M8. Although it is open-ended, the Richter

scale does not accurately measure large earthquakes on faults with a great rupture length.4 To

better quantify the severity of great quakes, scientists have developed the moment magnitude scale.

The moment magnitude (Mw) measures the total

seismic energy released, which is a function of

rock rigidity in the fault, the area of rupture on the

fault plane, and the amount of slip. These scales

are compared in table 2-1.

In contrast to magnitude, an earthquake’s intensity is a highly subjective measure. For many

years the Modified Mercalli Intensity (MMI)

scale, developed in 1931, has been used to describe the relative strength of ground shaking experienced at a particular location. Seismologists

assign intensity using the 12-increment scale that

reflects the effects of shaking on people, damage

to the built environment, and changes in the natu1 Nuclear explosions, for example, generate seismic waves that can be detected at great distances by earthquake-monitoring networks.

2 Strong motions are energetic ground displacements that cause damage to buildings and other structures.

3 U.S. Geological Survey, “The Severity of an Earthquake,” brochure, 1990. This report adopts the classification for quakes of different

strengths as follows (M=magnitude): moderate, M5-6; strong, M6-7; major, M7-8; and great, M>8.

4 Much of the energy of a large earthquake is transmitted via long-wavelength seismic waves, the frequency of which is too low to factor into

calculations of earthquake magnitude.
Chapter 2 Understanding Seismic Hazards 135
361 Reducing Earthquake Losses

Chile, 1960

Alaska, 1964

New Madrid, Missouri, 1812

Mexico, 1985

San Francisco, California, 1906

Loma Prieta, California, 1989

Kobe, Japan, 1995

San Fernando, California, 1971

Northridge, California, 1994

8.3

8.4

8.7

8.1

8.3

7.1

6.8

6.4

6.4

9.5

9.2

8.1

81

77

7,0

6 9

6.7

6.7

SOURCE: Rick Gore, “Lwmg with California’s Faults,” Nati~na/ Geographic, vol. 187, No. 4, April 1995, p 10

ral environments Table 2-2 provides an abbreviated description of the MMI scale.

Continuing research has illuminated both the

basic setting for earthquakes and their hazardous

effects. These two topics set the stage for understanding the seismic hazards that exist in different

areas of the country.

9 Geologic Setting for Earthquakes

The overall framework that guides the discussion

of earthquake occurrence is the theory of plate tectonics, a large-scale picture of the earth’s basic

workings originally set forth in the 1960s and

1970s.6 In this conceptual framework, the rocks

making up the outer layers of the earth are broken

into a patchwork of ever-shifting tectonic plates

(see figure 2-2). Some of these plates are enormous—the rocks underlying much of the Pacific

Ocean, for example, lie on a single IO,OOO-kmwide Pacific Plate—whereas others may span

only a few hundred kilometers. What distinguishes a plate, however, is that it moves as a

cohesive body across the surface of the earth.7 As

a plate moves, it grinds or knocks against its

neighbors; this plate-to-plate interaction produces

the majority of the world’s earthquakes.

With a few significant exceptions, identifying

the most likely breeding ground for darnaging

earthquakes is thus synonymous with finding the

boundaries of tectonic plates. The two types of

plate boundaries associated with damaging earthquakes in the United States are subduction zones

and strike-slip faults. In addition, there are intraplate earthquakes, whose origins are less well understood (see box 2-l).

I Earthquake Effects at

the Earth’s Surface

Besides knowing where and when earthquakes

might occur, those interested in reducing earth5 L~Qu~e lnten~ity,” Ear@uakes and Volcanoes, vol. 24, No. 1, 1993, P. 42.

15 It Should be noted hat many of tie dam that supported the theory’s development were derived from pre-NEHRPefforts (e.g., Department

of Defense mapping of seafloors, and global seismic monitoring aimed at detecting nuclear testing in the former Soviet Union).

7 This motion is slow—usually on the order of a few centimeters or less per year. Over millions of years, however, it can carry continents

from the equator to the poles, rip landmasses apart, or assemble disconnected land fragments into continents.

8 In~aplate qu~es, which can strike deep wi~in a plate’s interior, are relatively rare. There are also earthquakes associated with mOuntainbuilding and active continental deformation far inland from plate boundaries. One theory is that such activity in western states reflects the presence of a diffuse plate boundary stretching from the Pacific coast to the front ranges of Utah, in which case earthquakes in the Intermountain

West are not “intraplate” quakes at all. This report adopts the convention that the North American Plate ends near the Pacific coast and that

earthquakes in the Interrnountain West are intraplate events.
Chapter 2 Understanding Seismic Hazards 37

MMI Description

I Not felt except by a very few under especially favorable circumstances.

II Felt only by a few persons at rest, especially on upper floors of buildings.

Ill Felt quite noticeably indoors, especially on upper floors of buildings.

Iv During the day, felt indoors by many, outdoors by few. At night, some awakened.

v Felt by nearly everyone; many awakened. Some dishes, windows broken; a few instances of cracked plaster; unstable

objects overturned

V I Felt by all; many frightened and run outdoors. Some heavy furniture moved; a few instances of fallen plaster or damaged chimneys. Damage slight.

Vll Damage negligible in buildings of good design and construction; slight to moderate in well-built ordinary structures;

considerable in poorly built or badly designed structures. Some chimneys broken.

Vlll Damage slight in specially designed structures; considerable in ordinary substantial buildings, with partial collapse;

great in poorly built structures. Chimneys, factory stacks, columns, monuments, and walls fall.

lx Damage considerable in specially designed structures; well-designed frame structures thrown out of plumb, damage

great in substantial buildings.

x Some well-built wooden structures destroyed; most masonry and frame structures destroyed with foundations; ground

badly cracked Rails bent.

X l Few masonry structures remain standing, Bridges destroyed,

XII Damage total Lines of sight and level distorted. Objects thrown upward into the air.

SOURCE: U.S. Geological Survey, “The Severity of an Earthquake,” brochure, 1990.

quake losses are concerned with what effects an

earthquake might have on nearby communities.

Earthquake engineers, for example, desire quantitative assessments of expected ground motion or

deformation in order to evaluate the likely impact

on buildings or lifelines.9

Ground Shaking

Contrary to the popular image in Hollywood movies or the more spectacular literary accounts, the

earth generally does not open up and swallow

buildings during earthquakes. Cracks and fissures

do occasionally break the earth’s surface. However, they are secondary effects of the most damaging earthquake phenomenon—strong ground

shaking caused by seismic waves.

Analogous to sound waves,10 seismic waves

can be produced at different frequencies (corresponding to the pitch of a musical note) and at different amplitudes (corresponding to volume).

Large earthquakes (which involve big motions on

big faults) tend to produce larger amplitude, lower

frequency waves. In reality, however, all earthquakes produce a complex suite of different waves

of varying amplitudes and frequencies.

The damage done to structures and their contents depends on the characteristics of the ground

motion. The shaking may be up and down, side to

side, or some complex combination of the two.

There may be a short flurry of rapid, energetic motions followed by rolling or swaying motions that

last several seconds or more. Higher frequency accelerationsll primarily affect shorter, stiffer structures; repetitive, lower frequency motions pose a

special threat to very tall or flexible structures.

Displacements produced by very large amplitude

9 Lifelines are roads, bridges, communication systems, utilities, and other essential infrastructure. See chapter 3.

10 One type of seismic wave, the P-wave, is in fact an underground sound wave.

11 Acceleration is commonly expressed as a fraction of the strength of earth’s gravity, g . A vertical acceleration of more than 1 g can actually

throw objects in the air.
38 I Reducing Earthquake Losses

SOURCE: Office of Technology Assessment, 1995, based on Bruce A. Bolt, ,!Sarfhquakes (New York, NY: W.H. Freeman and Co , 1993), p 36

waves can stretch or twist structures beyond their

engineering limits. The frequency, energy content, and duration of shaking are not related simply to earthquake size, but also to distance from

the fault, direction of rupture, and local geology,

including soil conditions.

Increasingly, earth scientists have applied

state-of-the-art R&D to determining what sort of

ground acceleration and displacement is to be expected in different earthquake regions. Such estimates require knowledge (or prediction) of what

waves are originally generated by the earthquake

(which implies an understanding of exactly how

earthquakes occur) and of how these waves decay,

grow, or combine as they travel through the earth.

The latter requires geophysical and geological

mapping of the rocks between the earthquake and

the area of concern.

Because softer soils and clay tend to amplify

ground motions, compared with those experienced on bedrock, research has also been directed

at how seismic waves interact with sutilcial and

near-surface materials to enhance ground shaking.

A dramatic example of the effects of localized

geology was the 1985 Mexico City earthquake;

ground motions there were significantly enhanced

at periods of several seconds compared with those

at hard-rock sites closer to the quake source 12 (see

box 2-2).

12 ~omas H. Heaton and stephen H. I-lamell,’’EafiqU& Ground Motions,’’ Annual Review ofEarth Planerary Science, VO1. 16, 1988, P.

124.
Chapter 2 Understanding Seismic Hazards 139

Subduction Zones

In Alaska and the Pacific Northwest, the overriding of the North American continent over the various

plates of the Pacific Ocean has led to the formation of subduction zones, a type of plate boundary that

generally produces very large earthquakes. In a subduction zone, the layers of rock making up an oceanic

plate move toward a landmass and, in the resulting collision, are forced down into the earth’s deep interior.

In the Pacific Northwest, this collision is responsible for the presence of the region’s coastal mountains, for

the volcanic activity that has produced the Cascade Mountain Range, and—most significantly—for the potential for major earthquakes to occur where the subducting plate is stuck, or locked, against the overriding continent. In most cases, this is at depths of 15 to 45 km (1 O to 30 miles).

Earthquakes in subduction zones generally reflect the presence of thrust faults ---fractures in the earth

that allow one rock mass to slide toward and over its neighbor, The seismic waves thus generated shake

the ground upward and downward as well as forward and back. Because the faults allow for vertical motions, subduction zone earthquakes can lead to the uplift or subsidence of local landmasses, over time

flooding coastal areas or leaving them high and dry. If the earthquake occurs offshore beneath the ocean

(the plate boundary in a subduction zone generally lies underwater and out of sight), the vertical motion of

the sea bottom can send a surge of water (a tsunami ) racing toward vulnerable seaside communities. Finally, since subduction zones are typically mountainous (because of all the vertical fault motion), strong

subduction temblors can set off major landslides, avalanches, or mudflow.

Strike-Slip Plate Boundaries

A very different type of plate interaction is at work in California and southeast Alaska. Here, the Pacific

Plate (on which Baja California and the westernmost sliver of the North American continent rest) slides

sideways against the North American Plate in a motion known geologically as strike-slip. On a strike-slip

boundary, there is very little up-and-down motion, most earthquake waves are side to side, and seismic

activity does not raise mountains or produce tsunamis in the way it does in a subduction zone.

In the case of California, the seam between the North American and Pacific Plates is the San Andreas

fault, a long and distinct scar in the earth’s surface that runs beneath San Francisco, through central

California, and southward toward Mexico through the desert east of Los Angeles. q There is another strikeslip plate boundary fault off the coast of southeast Alaska. Earthquakes occur along these faults primarily

because relative motion, or slip, along either fault is not continuous over time or distance. That is, the fault

is locked most of time, so that no slip occurs. The inexorable movement of the tectonic plates, however,

causes stress to build along the fault until, for poorly understood reasons, one or more segments of the

fault rupture, releasing the stored-up energy in an earthquake.

In California, most of the slip between the North American and Pacific Plates occurs along the San Andreas fault or in the immediate vicinity. Some deformation of the plate edges also occurs many miles from

the primary fault, leading to stress-relieving earthquakes on strike-slip faults located on either side of the

San Andreas. An example is the 1992 Landers earthquake (M7.3). The largest U.S. earthquake in 40 years,

it occurred in a relatively sparsely populated area several miles northeast of Los Angeles.

I

1 A continuous narrow break in the earth’s crust, the entire fault zone is more than 800 miles long and extends at least 16 km beneath the earth’s surface. Sandra E Schulz and Robert E. Wallace, The San Andreas Fault, prepared for the U.S. Geological Survey

(Washington, DC. U.S. Government Printing Office, 1993), pp. 3-4.

(continued)
40 I Reducing Earthquake Losses

A pronounced bend in the San Andreas north of the Los Angeles area effectively locks the motion of the

tectonic plates, contributing to vertical deformation and setting the stage for earthquakes on downwarddipplng faults hidden from view beneath the earth’s surface. The 1971 San Fernando and 1994 Northrldge

quakes both ruptured such “blind” thrust faults,

Intraplate Earthquakes

Although more than 90 percent of the world’s earthquakes occur on plate boundaries, damaging earthquakes have also occurred m areas far from plate edges. /ntrap/ate earthquakes, which though uncommon

can be sizable, seem to reflect processes that are a topic of current tectonic and geophysical research

Possible explanations include: 1) dynamic interactions between the earth’s stiff exterior layers and Its

deeper, more flowing mantle; 2) a continent’s adjusting to evolving plate boundary geometries (the Basin

and Range Province of Nevada, for example, is stretching east-west following the disappearance of a subduction zone that once lay to the west); or 3) the interaction between zones of weakness wlthln a plate and

stresses transmitted across the plate from its boundaries,

The regions of the United States in which future intraplate earthquakes are most Ilkely to occur are the

Intermountain West and central United States, although parts of the Atlantic seaboard are also susceptlble.2 Compared with interplate earthquakes, uncertainty over the origin, Iikellhood, severity, and characterishcs of intraplate quakes is very high, Improved understanding can come only through further basic earth

science research.

z The eastern coast of North America, while marking the edge of the continent, IS not a plate boundary North America IS joined

directly to the rocks underlying the western half of the Atlantlc Ocean, and the eastern boundary of the North American Plate hes In the

middle of the Atlanhc,

SOURCE Office of Technology Assessment, 1995

—

Jther EtYects ● ground rupture, in which shaking opens up fisThe shaking caused by seismic waves, in addition

to directly damaging structures, can also affect the ■

earth’s surface in ways equally detrimental (or

more so) to the built environment. Ground failure,

as these effects are often called, has several different facets: ■

- 1 iquefaction, whereby shaking transforms a ‘

water-saturated soil or sediment into a thick,

quicksand-like slurry;

sures and cracks in the soil;

surface faulting, in which an earthquake fault

reaches the surface of the earth and produces

vertical or horizontal ojjlkets of material astride

the fault;

landslides or avalanches; and

damaging water waves (e.g., tsunamis and

seiches). 13

13 Fast-moving surge5 of water [hat [rave] across the ocean, fsunamis form a steep wall of water when entering shallow water ~lonk? shorelines. The local wave height and run-up length are affected by the topography of the seafloor and continental shelf and by the shape of the shoreline—tsunamis with crests as high as 25 meters have devastated parts of Japan. Bruce A. Bolt, Earthquakes (New York, NY: W.H. Freeman and

Co., 1993), pp. 148, 151. Tsunami generation is not fully understood, and may result more from the absolute motion of material at an earthquake

fault than from the ground shaking from seismic waves. Seiches are earthquake-generated surges of water on lakes and enclosed bays.
Chapter 2 Understanding Seismic Hazards 141

On September 19, 1985, Mexico City experienced the effects of an M8.1 quake that occurred in a subduction zone 350 km away Strong shaking caused extensive damage, killed thousands of people,1 and left

many more thousands homeless Most of the damage was confined to areas of the city built on soft, watersaturated soils

Key factors in the devastating losses Included:

■ the long duration of shaking,

■ local soil conditions that amplified seismic energy and produced extensive liquefaction,

■ poor overall configuration and significant irregularities in the distribution of buildings mass, strength,

and stiffness, and

● poor quality control of building materials.

Rupture on the segment of a subduction zone known as the Michoacan gap produced approximately

1 5 minutes of shaking with a roughly two-second period. (Higher frequency motions were damped over

the distance between the earthquake’s focus and Mexico City.)

Liquefaction was widespread, and soil-structure interaction increased the structural response of many

multistory buildings to a period that coincided with the long-period motion produced by the quake. The

effects of this resonance Included drift, deformation, and pounding between buildings

1 The official count iS 4,596 lives lost, although other estimates areas high as 20,000

SOURCE: Applied Technology Council and Earthquake Engineering Research Institute, Proceedings of the Workshop for Utilization

of Research on Engineering and Socioeconomic Aspects of the 1985 Chile and Mexico Earthquakes, ATC-30 (Redwood City CA

Applied Technology Council), 1991

Like strong ground shaking, ground failure is

strongly dependent on the surface and near-surface geology. Areas adjacent to waterways and developed with artificial fill are particularly

susceptible to liquefaction, as seen in the Marina

district in San Francisco during the 1989 Loma

Prieta earthquake and in the 1995 Hyogoken-Nanbu earthquake that struck Kobe, Japan. Lateral

spreading (in which surface layers are transported

laterally over liquefied soils) ruptured water and

sewer lines in the Kobe quake. The shaking produced by the 1994 Northridge, California, quake

and its aftershocks caused thousands of landslides

in nearby mountains.

SEISMIC HAZARDS ACROSS

THE UNITED STATES

Earthquake researchers use an understanding of

the basic setting for earthquakes and knowledge of

prior earthquakes to assess seismic hazards and relate these to affected communities. Earthquake

hazards vary widely across the country, from high

in Alaska and the West Coast to low (but not zero)

in much of the eastern United States. There is a

continuum of earthquake risk,14 as well: where

heavy urbanization exists and frequent damaging

earthquakes are expected, the risk is very high

(e.g., in the San Francisco Bay or Los Angeles

14 Seismic hazard is the potential for an earthquake and related effects to occur. Seismic risk is the likelihood for casualties, damage to the

built environment, or other losses to occur as a result of earthquakes.
42 I Reducing Earthquake Losses

BRITISH COLUMBIA,

CANADA

/

Pacific /

Mt. Rainier

OREGON

North

American

Plate

Plate

y \

< > ** T

1980 Mt. Shasta

d 1

0

+f 1CJCJ2

I

)

NEVADA

100 San

Andreas CALIFORNIA

Miles fault +

NOTE * indicates earthquakes of magnitude greater than 7

SOURCE Ofhce of Technology Assessment, 1995, based on U S Geological Survey

areas). In the Pacific Northwest, the seismic risk

stems from the potential for infrequent but large to

great earthquakes and from the region’s status as a

relative newcomer to mitigation (i.e., fewer steps

have been taken to reduce risk). Likewise, central

and eastern areas of the United States face the

threat of significant earthquakes over very long intervals; the low frequency of damaging seismic

events in recent history has contributed to the

more limited implementation of mitigation measures than in the West, despite the vulnerability of

many population centers (e.g., New York City or

Boston) to even moderate shaking. The following

sections describe current knowledge of earthquake hazards in different regions of the United

States.

S Pacific Northwest

The coastal area stretching from Alaska’s western

Aleutian Islands to the states of Washington and

Oregon is at risk for both moderate and enormously powerful earthquakes. This area encompasses

the growing metropolitan areas of Seattle, Portland, and Anchorage, as well as cities on Canada’s

west coast. Estimates of possible earthquake magnitudes in the region range as high as magnitude 9

(see figure 2-3).
Chapter 2 Understanding Seismic Hazards | 43

The convergence of tectonic plates creates a

high likelihood of seismic activity. For this reason, Alaska frequently experiences potentially

damaging earthquakes, but due to its relatively

low population density the impact is smaller than

in more developed areas. In 1964, the second largest quake of this century struck Alaska, uplifting

sections of the ocean floor and causing extensive

damage to the Anchorage area. The Mw9.2 quake

also caused a tsunami that led to further loss of life

and damage in Alaska and in the northern California coastal town of Crescent City.

If such a temblor occurred further south, it

could affect coastal communities from Vancouver, British Columbia, to northern California.

However, off the coasts of Oregon and Washington, there have been no quakes of this size during

recorded history. Awareness of this particular seismic threat was low until evidence of tsunami deposits and changes in coastal elevation, gathered

in large part through NEHRP, revealed that great

subduction zone earthquakes had occurred in the

past. Based on tsunami records from Japan, the

most recent may have been in the year 1700.15

Moderate-to-large crustal earthquakes in Oregon and Washington have been relatively infrequent, but the risk to population centers is

significant. A major quake struck the Cascades of

northern Washington in 1872;16 the Puget Sound

region experienced quakes of magnitudes 7.1 and

6.5 in this century;17 and as recently as March

1993, a M5.6 temblor rocked the Oregon capital

city of Salem.18

Uncertainty remains over how likely or how severe future events may be. Research into this

question, much of it involving the modeling of

geophysical processes in the region, is active and

growing, and may eventually remove much of this

uncertainty. In the meantime, complementary research into paleoseismology (the study of early

historic or prehistoric earthquake activity based

on geologic evidence) seeks to refine estimates of

the timing and magnitude of previous subduction

zone and crustal quakes. Besides indicating that

prehistoric, devastating tsunamis occurred, the

geologic record also suggests that a major earthquake took place 1,100 years ago directly beneath

what is now downtown Seattle.19

❚ California

A combination of high population density, heavy

levels of urbanization, and the relatively frequent

occurrence of moderate to great earthquakes

makes California a state with very high seismic

risk. Other areas in the United States may experience equally severe earthquake disasters, but the

likelihood is lower.

For many years it was thought that the earthquake hazard in California stemmed primarily

from the great San Andreas fault system, which

accommodates the sliding of the North American

continent sideways against the Pacific Plate. Several M8+ earthquakes have occurred along the San

Andreas, including the great 1906 San Francisco

Earthquake. The long-awaited “Big One” is ex15 Kenji Satake et al., “A Possible Cascadia Earthquake of January 26, 1700, as Inferred from Tsunami Records in Japan,” Geological Society of America 1995 Abstracts with Programs, vol. 27, No. 5, 1995, p. 76.

16 Reported effects indicate that its magnitude was approximately 7.4, probably the largest during recorded history for that area. Thomas

Yelin et al., Washington and Oregon Earthquake History and Hazards, U.S. Geological Survey Open File Report 94-226B (Denver, CO: National Earthquake Information Center, 1994), p. 7.

17The quakes took place in 1949 (M7.1) and 1965 (M6.5); both deep quakes (depths of 54 to 63 km), they caused several deaths and significant damage. Linda Lawrance Noson et al., Washington State Earthquake Hazards, Information Circular 85 (Olympia, WA: Washington Department of Natural Resources, 1988), p. 21.

18 Six months later, a pair of strong quakes occurred a little more than two hours apart near Klamath Falls, in the southern part of the state.

Shallow crustal quakes like these have also occurred in the Portland area. Yelin et al., see footnote 16.

19 Ibid., p. 9.
44 I Reducing Earthquake Losses

‘,

Looking northwest along the San Andreas fault, the seam

between the North American and Pac/f;c P/ates, m the Carnzo

P/a/n (central Ca//forn/a)

pectcd to involve rupture of the fault’s southern

section.

A more recently recognized danger is the likelihood of future moderate-to-large earthquakes occurring on lesser known or even unsuspected

faults adjacent to or directly underneath major

metropolitan centers (see figure 2-4). The quake

beneath Northridge in January 1994 revealed all

too well the hazardous potential of blind thrust

faults in the Los Angeles area.20

The danger of these blind thrust systems is a

combination of the size of their associated earthquakes and their proximity to urban centers. Because an earthquake’s damaging effects tend to

decrease rapidly with distance, the physical separation between the San Andreas and a metropolitan center such as Los Angeles allows

policy makers to prepare the built environment

against a lesser amount of damage than sheer

earthquake magnitude might seem to warrant.

However, if a fault capable of producing earthquakes is close by, then its proximity allows even

a moderate event to inflict more damage than

might result from the long-awaited “Big One.”*l

In northern California, the geometric complexity of the San Andreas fault system that prevents

North America from sliding cleanly against the

Pacific Plate causes the San Andreas to branch off

into a series of smaller faults that run in a northsouth direction along the east side of San Francisco Bay (see figure 2-5). In addition to the 1906 San

Francisco and 1989 Loma Prieta earthquakes, the

Bay Area has experienced 20 other moderate to

great earthquakes in the last 160 years .22

Because of these and other findings from recent

research, the true earthquake hazard in California

remains uncertain, and future estimates may well

be subject to upgrading. As of 1990, the estimated likelihood of major (M7+) earthquakes

stands at 67 percent over 30 years in the San

‘() Sel\mograph and strong-motion instrument data recorded during and after the Northridge earthquake indicate larger ground motions

than ha~ e typically been observed or reflected in engineering design in California. The aftermath of the quake included realization that improved knowledge of the system of blind thrust faults lying beneath the Los Angeles area and environs would be useful for targeting mitigation

efforts. While oil company studies are a good source of information about subsurface structure, the mapping rarely extends to depths where

earthquakes initiate.

z I 1t ~ippear$ that one such fault. [he E]ysian park blind thrust fault, lies directly beneath downtown LOS Angeles.

~z Association of Bay Area Governments, ‘The Bay Area Is Earthquake Country,” Internet, address http: //www.abag.ca.gov/bay area/eq -

maps; doc~text 1.html#background, citing Jeanne B. Perkins and John Boatwright, The San Francisco Buy Area--On Shakv Ground (Oakland,

[“A. A\w)clatlon of Bay Area Governments, April 1995).
Chapter 2 Understanding Seismic Hazards 145

NOTE: Shaded areas represent rupture zones for earthquakes shown

SOURCE U S Geological Survey, 1995

Francisco Bay area.

23 Studies of the potential for

liquefaction and ground failure that would result

from shaking on the San Andreas and its neighbors across the Bay are continuing, 24 as are investigations of local fault structures.

The 30-year probability of a major earthquake in southern California, estimated in

1994, is 80 to 90 percent (this estimate reflects

both San Andreas and blind thrust hazards for the

urban corridor from San Bernardino through Los

Angeles to Santa Barbara).25 Scientists have also

noticed a historical deficit in the size or number of

earthquakes expected for southern California;

23The primary fault structures evaluated for the assessment were nearby segments of the San Andreas fault and the neighboring fault system

east of the bay, which consists of the Hayward and Rodgers Creek faults. Working Group on California Earthquake Probabilities, Probabilities

of Large Earthquakes in the San Francisco Bay Region, California, U.S. Geological Survey Circular 1053 (Washington, DC: U.S. Government

Printing Office, 1990), p. 31.

24 This is an area of cooperation between USGS and the California Division of Mines and Geology, the state agency responsible for mapping

special hazard zones.

25 Working Group on California Earthquake Probabilities, “Seismic Hazards in Southern California: Probable Earthquakes, 1994-2024,”

Bulletin of the Seismological Society of America, vol. 85, No. 2, April 1995, p. 379; USGS and SCEC Scientists, “The Magnitude 6.7 Northridge,

California, Earthquake of 17 January 1994,” Science, vol. 266, Oct. 21, 1994, p. 396.
46 I Reducing Earthquake Losses

Pacific Ocean

L I

[1~‘+ “u! ! “Uuu

j $ \ 1989

\ Loma Prieta

“\

$5. M7.1

o

~

+ Santa Cruz

50 km

\

■ *

7

—, San Juan

Bautista Hollister

SOURCE U S Geological Survey, 1995

geologic and geodetic data indicate that too few

earthquakes have occurred to account for strain

accumulation. 26 Whether this points to bigger

quakes or to more frequent quakes is still under

discussion in the scientific community.

I Intermountain Seismic Belt

A region not commonly associated with seismic

hazards—yet nevertheless under considerable

risk—is the Intermountain Seismic Belt. Stretching from southern Idaho and western Montana

down through southwestern Utah and Nevada,

this area includes the urban center of Salt Lake

City, Utah, and other rapidly growing communities in the Intermountain West (e.g., Boise, Idaho,

and Reno, Nevada).

Earthquakes here do not stem from the plate

collisional processes of the Pacific Northwest or

from the sideways sliding of adjacent plates seen

in California. Rather, they arise from intraplate

deformation of the North American continent

associated with the uplift of the Rocky Mountains

26 James F. Dolm et ~l., “~os~cts for Larger or More FreqUent E~hquakes in the LOS Angeles Metropolitan Area.” Science. VO]. 267, Jan.

13, 1995, p. 203; and Working Group on California Earthquake Probabilities, see footnote 25.
Chapter 2 Understanding Seismic Hazards | 47

and the east-west stretching of the Basin and

Range Province. Because this region lies within

the interior of the North American Plate and far

from the active deformation, collision, and sliding

experienced at the plate edges, damaging earthquakes are relatively rare. However, since these

earthquakes reflect active mountain-building

processes in the continental interior, when they do

occur, they can be sizable (M7 or higher).

Even though the maximum earthquake magnitudes in this region appear to be less severe than

those projected or observed in the Pacific Northwest or California, the potential for disaster exists

simply because the scarcity of historic earthquakes has led to a relatively low level of preparedness. General settlement of the area did not

begin until the 1840s; in the intervening years,

there have been no large quakes near the region’s

few urban centers. Consequently, damaging earthquakes have generally been less of a public concern than is the case in California. The region’s

last major quakes were in Montana in 1959, when

several people were killed by landslides, and

southern Idaho in 1983.

Awareness of the threat to Utah’s metropolitan

corridor grew as a result of a major NEHRP project to study the Wasatch Front, which is formed by

the uplift of the Rocky Mountains along a long,

north-south fault zone—the Wasatch fault zone

(see figure 2-6). The research showed that major

earthquakes have occurred in the past, with paleoseismic evidence suggesting a roughly 400-year

recurrence along the most urbanized part of the

Wasatch fault zone.27 In 1991, the probability of

a M7+ earthquake anywhere along the Wasatch was estimated to be 13 percent over a

50-year period.

28 An earthquake of that size anywhere along the fault zone will be felt throughout

NOTE: Thick Iine designates the Wasatch fault About 80 percent of

Utah’s population, or nearly 16 million people, are at risk to movement

of the fault.

SOURCE: U.S. Geological Survey, 1995

the system, and is likely to damage structures in

the closest cities.29

Although a major earthquake in a California

city would cause considerable damage and loss of

life, an occurrence in less-prepared Utah could be

27 Michael N. Machette et al., “Paleoseismology of the Wasatch Fault Zone: A Summary of Recent Investigations, Interpretations, and Conclusions,” USGS Professional Paper 1500-A, November 1990, p. A55. Led by USGS and the Utah Geological and Mineral Survey, the project

was completed in the early 1990s; seismic hazard and risk assessment continues today under state and local authorities.

28 S. Nishenko, “Probabilistic Estimates for the Wasatch Fault,” in Proceedings of the National Earthquake Prediction Evaluation Council,

June 11-12, 1991, Alta, Utah, USGS Open File Report 92-249 (Washington, DC: U.S. Geological Survey, 1992), pp. 16-19.

29 Kaye Shedlock, U.S. Geological Survey, Earthquake and Landslide Hazards Branch, personal communication, Apr. 15, 1995.
48 | Reducing Earthquake Losses

far worse.30 Moreover, continued population

growth in the region will likely lead to urbanization in areas relatively untargeted (until recently)

by earthquake researchers; this raises the possibility of additional damage in areas currently unaware of their seismic hazard.

❚ Central United States

A series of three great earthquakes occurred between December 1811 and February 1812 near

New Madrid, Missouri, opening chasms in the

earth, destroying the scattered settlements in the

region, and causing sections of the Mississippi

River to temporarily reverse and flow backward.

Although there were no modern seismographic

instruments available then to record the quakes’

magnitudes, the level of destruction witnessed

places these events among the most powerful

ever.31

The challenge to the earth science community

has therefore been to determine the likelihood of

future damaging earthquakes in this region, and to

decide whether the great New Madrid earthquakes

were a geophysical fluke or the offspring of geologic conditions specific to the region.32 In many

respects, this task has been more difficult to perform than is generally the case in the western

United States, because earthquakes in the central

and eastern United States cannot be accounted for

by classic plate tectonic theory. Compounding

this difficulty is an observational problem caused

by the presence of the Mississippi. Sediments carried by the river and deposited overland during

floods over the eons have blanketed the region

with kilometers of mud, sand, clay, and soil that

effectively hide potential earthquake faults from

view.33

About a decade ago, a major success was

achieved in the identification of a geologic structure that appears tied to the region’s earthquakes.

This structure, the Reelfoot Rift, is a buried series

of faults and anomalous rock formations formed

500 million years ago when tectonic forces tried

but failed to split North America in two.34 The

rifting event in effect drew a wounding scar

through the more-or-less contiguous landmass of

the central and eastern United States. It is this singular zone of weakness (identified through geophysical surveys) that may account for the New

Madrid earthquakes (see figure 2-7).

Thus, it appears that seismicity in this area is

tied to a particular geologic structure, and is not

expected to recur randomly elsewhere (see figure

2-7). However, scientists have also learned that

any earthquakes that do occur in the eastern half of

the United States will be felt far more widely than

30 A 1976 USGS study, for example, projected 14,000 fatalities in the event of a major Wasatch Front event. The Salt Lake area has since

upgraded its seismic zone status and implemented hazard assessment and mitigation projects.

31 With MMI of XI and XII, these temblors were the largest to occur within the coterminous United States; the 1812 quake was felt throughout an area of 5 million square kilometers. For comparison, the great San Francisco earthquake of 1906 had an MMI of XI and registered 8.3 the

Richter scale. William Atkinson, The Next New Madrid Earthquake: A Survival Guide for the Midwest (Carbondale and Edwardsville, IL:

Southern Illinois University Press, 1989), p. 22; and Bolt, see footnote 13, pp. 5, 270, 277.

32 The former conclusion would suggest that a repeat might occur virtually anywhere in the United States; the latter, although disquieting to

local residents, at least confines the likely region of future devastation.

33 Although the deep sedimentary cap precludes direct observation of the faults, sedimentation facilitates paleoseismic work, and some

information about the region’s tectonic structures can be inferred by its topography. Geologic evidence indicates that three large earthquakes

have occurred in the New Madrid area over the last 2,400 years, a recurrence rate comparable to that for the Wasatch fault or many reverse faults

in California. Robert Yeats, Department of Geosciences, Oregon State University, personal communication, May 7, 1995; and see Keith I. Kelson et al., “Multiple Late Holocene Earthquakes Along the Reelfoot Fault, Central New Madrid Seismic Zone,” Journal of Geophysical Research, forthcoming, January 1996.

34 Robert M. Hamilton and Arch C. Johnston (eds.), Tecumseh’s Prophecy: Preparing for the Next New Madrid Earthquake, U.S. Geological Survey Circular 1066 (Washington, DC: U.S. Government Printing Office, 1990), p. 9. At the time, North America was joined to Eurasia and

Africa. Following the failure of the Reelfoot Rift, the landmass farther east split to form the proto-Atlantic Ocean.
Chapter 2 Understanding Seismic Hazards 149

37°

36°

35°

91o 90° 89°

NOTE: Shaded area shows region of intense liquefaction in 1811 to

1812 earthquakes, small hatches represent seismicity during 1974 to

1991, and heavy dashed lines indicate boundaries of the Reelfoot Rift.

SOURCE U S. Geological Survey, 1995

quakes that occur west of the Rockies (see box

2-3).

Given the potentially far-flung and devastating

effects of a major earthquake in the central United

States, it is critical that earthquake severity and

timing estimates are refined to the point that regional policymakers know the need and time scale

for action. Unfortunately, uncertainties for the region remain substantial. Although the presence of

the Reelfoot Rift provides an explanation for the

siting of earthquakes, it does not by itself predict

their occurrence. At present, there is no clear consensus on what mechanism causes tectonic stress

in the region to build up to the point of an earthquake. In the absence of a conceptual tectonic

model, the best guide to future earthquake activity

in this region lies in the record of past earthquakes.

This record suggests a recurrence of moderate

quakes every 60 to 90 years (the last moderate

event was in 1895). 35 The probability of an

M6.3 quake before 2040 is 86 to 97 percent; of

an M8.3 quake, 2.7 to 4 percent. 36

Furthermore, outside the immediate New Madrid Seismic Zone, the characteristics of the

source zones in the central (and eastern) United

States are poorly known. The region is virtually

devoid of identifiable active faulting,37 and geologic studies of seismogenic features are in the reconnaissance stage. Although current levels of

seismicity indicate a low hazard, NEHRP-supported studies have provided evidence of several

major quakes in the Wabash Valley area (southern

Indiana and Illinois) over the last 20,000 years.

❚ Eastern United States

The Pacific Northwest, California, Intermountain

West, and central United States have constituted

the primary earthquake concerns in this country

because the likelihood and potentially devastating

effects of damaging earthquakes are known with

greatest certainty in these regions. However. other

parts of the country are also at risk (although the

hazards are more uncertain) and may come more

to the forefront with continued research and understanding. These regions include the Atlantic

seaboard, which has experienced rare but moderately damaging earthquakes centered near

Charleston, South Carolina; Boston, Massachu35 Atkinson, see footnote 31, p. 1; and ibid., P. 8.

36 Hamilton and Johnson (eds.), see footnote 34.

37 Arch c. Johnston and susan J. Nava, seismic Hazard Assessment in the Central United States,” Proceedings of ATC-35 Seminar On New

Developments in Earthquake Ground Motion Estimation and Implications for Engineering Design Practice, ATC-35-1, Applied Technology

Council (cd.) (Redwood City, CA: Applied Technology Council, 1994), p. 2-7. An exception is the Meers Fault in Oklahoma, which has geologic expression indicative of previous strong earthquakes but very low modem seismicity.
50 I Reducing Earthquake Losses

The two halves of the North American continent have very different tectonic histories. East of the Rockies, the North American landmass has held together (the abortive Reelfoot Rift notwithstanding) for a good

part of the last billion years, and the tectonic plate material is strong In contrast, the continent west of the

Rockies has experienced repeated breakup, reassembly, uplift, compression, extension, and shear—heating and weakening it Seismic waves radiating from a western earthquake therefore diminish more rapidly

as they pass through fractured and heated rock, so that a major earthquake along the San Andreas can

have relatively moderate effects on the distant Los Angeles basin. East of the Rockies, however, seismic

waves are far less weakened as they radiate through hard, cold, strong rock, and even a moderate quake

has the potential for destruction over a wide geographic range.1

Relative Impact Areas for Severe Earthquakes in Western and Eastern United States

NOTE: Figure shows areas of Modified Mercalli Intensity of VI and Vll for two great earthquakes (New Madrid, Missouri, in 1811 and

San Francisco, California, in 1906) and two major damaging earthquakes (Charleston, South Carolina, in 1886 and San Fernando,

California, m 1971). Potential damage area corresponds to intensity Vll and greater, an area of roughly 250,000 square miles for the

New Madrid earthquake

SOURCE Off Ice of Technology Assessment, 1995, based on R Hamilton and A Johnston (eds.), Tecumseh's Prophesy Preparing

for the Next New Madrid Earthquake, U S Geological Survey Circular 1066 (Washington, DC U S Government Printing Office, 1990)

pp. 6, 12;O. W. Nuttli, “The MISSISSIPPI Valley Earthquakes of 1811 and 1812—lntensltles, Ground Motion, and Magnitudes” Bulletin

of the Seismological Society of America, voI 63, 1973, pp. 227-248, and D W Rankin (ed.), “Studies Related to the Charleston, South

Carolina, Earthquake of 188&A Preliminary Report, ” U S Geological Survey Professional Paper 1028, 1977

1 The 1812 New Madrid shock was felt in Boston, Canada, Georgia, and at least as far west as Kansas and Nebraska Moderate

ground shaking was felt over an area of nearly 1 million square miles, in contrast to some 60,000 square miles in the 1906 San Francisco quake. William Atkinson, The Next New Madrid Earthquake: A Survival Guide for the Midwest (Carbondale and Edwardsville, IL

Southern Illinois University Press, 1989), p 18

SOURCE Office of Technology Assessment, 1995
Chapter 2 Understanding Seismic Hazards | 51

setts; and northward toward the Saint Lawrence

Valley.

Puerto Rico and the U.S. Virgin Islands are at

risk from earthquakes in the Caribbean’s subduction zone. In 1917, Puerto Rico suffered a major

earthquake (M7).

❚ Limiting Factors in

Assessing Seismic Hazards

Damaging earthquakes have occurred in many

parts of the United States, and several metropolitan areas are located in regions of moderate to very

high seismic hazards (see table 2-3). Over the last

quarter of a century, understanding of these hazards has increased considerably. In the past five

years, advanced instrumentation and computerbased analytic tools have revolutionized earth science research and laid the groundwork for new

hazard estimation capabilities.

Despite the many achievements to date, uncertainties still plague our ability to characterize seismic hazards. Engineers desire better information

on the types of ground shaking expected for a given area so that methods for analyzing and improving a structure’s seismic resistance can be

enhanced. Likewise, planners and emergency

managers would greatly benefit from improved

knowledge of which areas in a city are likely to be

hardest hit by future earthquakes. Factors that limit our knowledge of faults capable of producing

earthquakes, of how often quakes occur on them,

and of their likely effects include the following:

 The historical and instrumental records are

very short compared with the time scales on

which earthquakes are generated, particularly

east of the Rockies.

 Most quakes begin rupturing 10 km or more beneath the surface of the earth: although some

earthquake phenomena and causative factors

are observed directly in surface faulting and

geodetic strain, other information must be inferred from seismological and other data.

 Detailed mapping of the structural features that

influence earthquake damage has been completed in only a small portion of the United

States.

 There are few records of strong ground motions

in close proximity to fault ruptures, and data on

crustal deformation and stress are likewise

sparse.

Such challenges to our understanding of seismic hazards and progress toward the long-term

goal of accurately predicting earthquakes will

likely be more readily surmounted in the future,

given the present confluence of new tools, trained

scientists, and expanded databases. These advances stem from work in the earth sciences supported by NEHRP and from other federal, state,

local, and international activities.

EARTHQUAKE-RELATED RESEARCH

IN EARTH SCIENCE

The preceding sections outlined some of the substantial progress made by the earth science community in achieving a basic understanding of the

earthquake problem. This understanding has

made it possible for policymakers to identify future trouble spots and to take preventive action.

Current knowledge of seismic hazards in different

regions, however, has not reached the point where

scientists and policymakers are no longer surprised by earthquakes and their effects. Scientific

uncertainties for much of the country remain high

enough to discourage the implementation of oftentimes costly mitigation measures. Under

NEHRP, earth science researchers seek to reduce

these uncertainties and to make available much

needed information for the implementation of

seismic risk reduction policies, practices, and

technologies. This section discusses current research efforts that address the primary knowledge

gaps.

❚ Objectives

The objectives of current earthquake-related earth

science include:

 identifying the regions of potential risk;

 producing or refining estimates of future earthquake location, timing, and severity;

 highlighting special geologic hazards that may

accompany future events (e.g., landslides, tsunamis, unusual ground shaking); and
52 I Reducing Earthquake Losses

Area Frequency/probability of return Comments on tectonic framework

Alaska

Pacific Northwest

Northern California

Southern California

HawaII

Intermountain West

Central United States

Northeast

Southeast

Puerto Rico and U.S.

Virgin Islands

Since 1900, one M8 or larger quake every 13 years, one M7+ quake every

year, and several moderate to large

quakes every year.

90-year return period for a M7.5.

67 percent chance of a M7 or greater

earthquake in the San Francisco Bay

area by 2020.

80-90 percent probability of a M7 or

greater earthquake before 2024 in greater Los Angeles area.

Frequent seismicity associated with volcanic activity; last major quake (M7.1 ) in

1975.

30 percent chance of major quake anywhere along Utah’s Wasatch fault zone

in the next 100 years.

Growing population centers elsewhere in

Intermountain Seismic Belt also susceptible to damaging earthquakes.

40-63 percent probability of recurrence

of M = 6+ quake in New Madrid Seismic

Zone before 2005, 86-97 percent probability before 2040, approximately

250-year return period for a M7.6 or

greater

300-year return period estimated for a

M7

Last moderate quakes in New York area

in 1944 and 1985.

Charleston, South Carolina, struck by

large quake (M6.7) in 1886.

High concentration of seismicity in eastern Tennessee

Last major quake in 1917; estimated

70-year return period.

Subduction zone along Aleutian Islands, Alaskan Peninsula,

and southern Alaska.

Frequent strong intraplate seismicity.

Damaging quakes also possible on strike-slip Queen Charlotte

fault in southeast Alaska.

Shallow crustal quakes, massive subduction zone quakes

possible offshore, and quakes within subducted plate deep

beneath Puget Sound.

Primary faults: strike-slip San Andreas and Hayward/Rogers

Creek faults on the east side of the bay; quakes on local blind

thrust faults also possible,

Northern California coast subject to quakes with several

sources: northern segment of the San Andreas, Cascadia

subduction zone, and inland crustal quakes.

Extensive rupture of strike-slip San Andreas possible, and

moderate-to-large quakes also likely on secondary fault systems, Extensive buried thrust fault system beneath the Los

Angeles basin as a result of compressional terrain

Faults near Los Angeles’ and San Diego’s port facilities pose a

similar threat as the fault that ruptured near Kobe, Japan, in

1995.

Repeatedly struck by tsunamis; landslide potential high,

Mountain-building region; normal faulting with large vertical

offsets possible from Utah northward through Idaho and into

Montana.

Abundant seismicity in New Madrid Seismic Zone, Iinked to

rifted margin; dispersed seismicity elsewhere in the region not

linked to specific faults,

“Stable” plate interior, with zone of relatively high seismicity

from Adirondacks up through St Lawrence Valley; dispersed

seismicity elsewhere. Several large earthquakes scattered

throughout region since 1600s, primarily in Canadian provinces,

Tectonic origin for seismicity in eastern United States unclear

Subduction zone where the Caribbean Plate meets the North

American and South American Plates

SOURCES: Working Group on California Earthquake Probabilities, Probabilities of large Earthquakes in the San Francisco Bay Region, California,

U.S. Geological Survey Circular 1053 (Washington, DC U S Government Printing Office, 1990), Working Group on California Earthquake Probabilities, “Seismic Hazards in Southern California. Probable Earthquakes, 1994 to 2024, ” Bulletin of the Seismological Society of America, vol 85, No 2,

April 1995, pp. 379-439; R. Hamilton and A Johnston (eds.), Tecumseh's Prophecy: Preparing for the Next New Madrid Earthquake, U.S. Geological

Survey Circular 1066 (Washington, DC U.S. Government Printing Office, 1990); K Shedlock and C Weaver, Program for Earthquake Hazards Assessment in the Pacific Northwest, U S Geological Survey Circular 1067 (Washington, DC: U.S. Government Printing Office, 1991 ), and Christine A

Powell et al , “A Seismotectonic Model for the 300-Kilometer-Long Eastern Tennessee Seismic Zone, ” Science, voI 264, Apr. 29, 1994, pp. 686-688
Chapter 2 Understanding Seismic Hazards | 53

 supporting scientific and engineering applications of earthquake data and theories.

Meeting these objectives and resolving some of

the unknowns laid out in the first half of this chapter requires continued effort in several research

disciplines. This work ranges from exploratory research into details of earthquake sources to applying new computational techniques toward

predicting ground failure or tsunami development. Earth science research and data collection efforts have been—and will continue to

be—essential to the development and selection

of mitigation options appropriate to a particular region’s seismic risk.

For the discussion that follows, earthquake-related research is grouped into two broad areas: 1)

basic research into the fundamental processes that

govern earthquake timing, location, and severity;

and 2) research applied toward predicting the effects of earthquakes, which in turn supports engineering analyses, land-use planning, and

emergency response.

❚ Foretelling Earthquake Timing,

Location, and Severity

The general theory of plate tectonics, while identifying where earthquakes should occur over the

long term, does not itself give clear warning of

earthquake likelihood or timing. This stems from

the difference between geologic time, which

spans thousands or millions of years, and the time

scales that are appropriate for public policy. Plate

tectonics suggests that if we were to wait several

millennia, we would expect earthquakes to occur

essentially everywhere along a plate boundary.

What it does not tell us is which specific parts of

that boundary will become active in the next few

years or decades. Moreover, plate tectonics does

not easily explain why earthquakes should occur

far from plate boundaries (as they do east of the

Rockies), and rising evidence suggests that the

theory is generally inadequate to describe the

large-scale tectonic behavior of continental

masses.38

To specify which part of a plate boundary is

likely to break in the near future, researchers must

go beyond the large-scale workings of the basic

plate tectonic model and identify how general

plate tectonic movements are translated into local

earthquakes. This quest entails a host of separate

research endeavors, the chief of which are regional tectonic studies, including geodetic studies;

fundamental seismological research and monitoring; and paleoseismology. The following sections

describe these research areas.

Regional Tectonic Studies

Regional tectonic studies seek to determine how

large-scale plate motions produce finer scale patterns of stress and deformation (e.g., uplift and

compression of the earth’s surface) in potential

earthquake zones. If earthquake-causing buildup

of tectonic stress can be correlated with the occurrence of tectonic deformation, areas of potential

danger can be identified even in the absence of historical seismicity through observing changes in

stress. Such an identification would be particularly useful in regions such as the Pacific Northwest

where major earthquakes have been historically

infrequent.

Tectonic studies also seek to identify hidden

structures that are capable of producing earthquakes (e.g., Los Angeles’ blind thrust faults)

through a combination of remote geophysical

techniques and onsite geologic mapping.39 For

example, scientists have studied how the relation38 Current indications are that the thinner oceanic parts of the earth’s surface act more plate-like (i.e., they are rigid and strong) but that

continents behave in a more complex fashion. For example, the Basin and Range Province of Nevada is stretching in an east-west direction

(generating low-level seismicity in the process), while the central and eastern parts of the country seem to consist of strong rigid blocks crisscrossed with weaker scars from ancient tectonic activity.

39 Methods of imaging subsurface geology and seismogenic structures include analysis of the passage of seismic waves through the earth,

and local changes in the earth’s magnetic and gravitational fields. When combined, the data reveal variations in material properties or rock types

that point to the presence of faults.
54 I Reducing Earthquake Losses

Japan initiated the first geodetic monitoring program at the turn of the 20th century, many decades before a similar program was established in the United States. 1 Today, both countries have implemented

state-of-the-art observation systems intended to reveal strain and stress accumulation from ongoing tectonic processes. Although geodetic measurements are now made in many areas, in only two areas—the

San Andreas strike-slip fault zone and the subduction zone along the southern coast of Japan—are there

sufficient data to attempt to reconstruct the entire quake-loading cycle.2

Very Long Baseline Interferometry and Global Positioning System

The paucity of data stems in part from the logistics of geodetic measurement techniques, which for years

required laborious field surveys. However, the availability of highly accurate clocks and digital telecommunications systems has brought significant advances to the field during the last decade or so. Very Long Baseline

Interferometry (VLBI) and, later, Global Positioning System (GPS) satellites have allowed expanded observation of crustal deformation and measurement of slip rates with greater accuracy.3 GPS-based techniques in

particular offer speedier calculations of relative distances and thus deformations. Other technical advantages

of GPS systems are: absence of line-of-sight constraints, simultaneous determination of vertical and horizontal

position, and a useful interstation range from hundreds of kilometers to less than one kilometer. 4

Regional networks of continuously recording GPS receivers are operating in Japan and California to

monitor strain for earthquake research and forecasting. Deployment of portable stations after an earthquake allows scientists to observe post-seismic deformations; these data complement data from seismographs concerning the depth, orientation, and amount of fault slip.5

1 Christopher H. Scholz, The Mechanics of Earthquakes and Faulting (New York, NY: Cambridge University Press, 1990), p 223

2 Ibid., p 227.

3VLBI uses radio waves from distant quasars as sources of ranging signals. GPS satellites broadcast time-stamped position data

at two different frequencies, allowing for correction of signal delays caused by the earth’s atmosphere and thus Improved resolution

4 Robert A. Page et al., Goals, Opportunities, and Priorities for the USGS Earthquake Hazards Reduction Program, USGS Circular

1079 (Washington, DC: U.S. Government Printing Off Ice, 1992), p 9

5 University Navstar Consortium, Geoscientific Research and the Global Positioning System. Recent Developments and Future

Prospects (Boulder, CO: 1994), pp. 3-4. The University Navstar Consortium (UNAVCO) provides information, support, and scientific

infrastructure to principal investigators making use of GPS satellites for earth science and related research.

ship between primary tectonic features such as the Geodetic Studies

Reelfoot Rift and the continental interior’s overall A number of technologies (see box 2-4) are used

stress regime may serve to localize seismicity in to observe and measure tectonic deformation.

the New Madrid area. 40 Such research may also These geodetic studies provide part of the raw mahelp to explain the spatial and temporal earth- terial for tectonic studies and serve as intermediate

quake clustering that has been observed in the checkpoints for earthquake forecasts based on

United States and other parts of the world.

40A current hypothesis is that most stable continental quakes occur through the reactivation of relatively young rift faults that break the

integrity of the continental crust. John Adams and Peter W. Basham, “New Knowledge of Northeastern North American Earthquake Potential,”

ATC-35-1, p. 3-7, citing Coppersmith et al., Methods for Assessing Maximum Earthquakes in the Central and Eastern United States: EPRI

Project 2556-12, Working Report (Palo Alto, CA: Electric Power Research Institute), 1987; and A.C. Johnston, “The Seismicity of ‘Stable Continental Interiors’” Earthquakes at North Atlantic Margins: Neotectonics and Postglacial Rebound, S. Gregerson and P.W. Basham (eds.) (Dordecht, Netherlands: Kluwer Academic Publishers, 1989), pp. 299-327.
Chapter 2 Understanding Seismic Hazards 55

Synthetic Aperture Radar Imagery

An even more recent departure from established ground-based geodetic measurement techniques is the

use of remote sensing to produce detailed images of deformation fields. Microwave signals generated by

synthetic aperture radar (mounted on aircraft or satellites) and reflected off the ground are processed to estimate displacement.6 Unlike most geodetic techniques, a surveyed network need not be in place prior to an

earthquake-satellite images collected at regular intervals can capture co-seismic displacements without

advance knowledge of an earthquake’s location.7 Other advantages of Synthetic Aperture Radar imagery

include more dense spatial sampling and better precision than previous space imaging techniques.

Laser Interferometry

Near Parkfield, California, the U.S. Geological Survey has been using a two-color laser distance measuring instrument (geodimeter) to observe relative movement in the vicinity of the San Andreas fault. The

two-color geodimeter measures distances to a precision of 0.3 to 1.0 mm for ranges between 1 and 9 km.

In-fault Measurements

A number of instruments placed at various depths in an active fault zone also help to reveal ongoing

deformation either directly (eg., through creepmeters and strainmeters) or indirectly (e.g., through

changes in water level or pore pressure). Creepmeters continuously monitor fault movement within a few

meters of fault zones to characterize the rate and nature of fault slip. They can detect changes of about 0.1

mm. Borehole volumetric strainmeters can detect changes of 10 parts per billion (1 inch in 1,600 miles) for

signals with periods of several weeks and, for higher frequency signals, can detect even smaller changes.

6 William Prescott, “Seeing Earthquakes from Afar,” Nature, vol. 364, July 8, 1993, pp. 100-101.

7 Didier Massonnet et al., “The Displacement Field of the Landers Earthquake Mapped by Radar lnterferometry," Nature, vol 364,

July 8, 1993, p 138

SOURCES: Office of Technology Assessment and U.S. Geological Survey, 1995.

models of regional tectonics. For example, geo- The advent of space-based geodetic techdetic data are used to infer rates of regional plate niques, such as Very Long Baseline Interferomemotion that, along with seismologic or geologic try, Satellite Laser Ranging, and most recently,

evidence of fault locations, can provide estimates surveys using the Global Positioning System

of the hazard from these faults. 41 Important data (GPS), has revolutionized this field of study.42

are also obtained from strain measurements at With these newer techniques, it is possible to didepth (e.g., through borehole monitoring of po- rectly observe crustal deformation, which may acrosity).

41 USGS and SCEC Scientists, see footnote 25, p. 395.

42 The first two technologies were developed under the aegis of the National Aeronautics and Space Administration’s (NASA) Crustal Dynamics Project, a program aimed at directly measuring the relative velocities of tectonic plates on a global scale; the original geoscientific applications of GPS stemmed from this work. University Navstar Consortium, Geoscientific Research and the Global Positioning System: Recent

Developments and Future Prospects (Boulder, CO: 1994), p. 1. Today, under NASA’s Mission to Planet Earth Program, space-based geodetic

technology development and research continues.
56 | Reducing Earthquake Losses

celerate the development of reliable earthquake

forecasting.

Fundamental Seismological Research

To better understand how stresses in the earth

eventually lead to the rupturing of a fault and the

production of an earthquake, scientists monitor

earthquakes via global and regional seismic networks (coordinated systems of sophisticated seismic listening and measuring devices, known as

seismometers; see box 2-5) and compare the

seismology data collected with results from

theoretical and laboratory models of earthquake

generation.

Questions central to seismological research include the following:

 How does an earthquake initiate?

 What determines whether a growing earthquake becomes large, moderate, or small?

 Can a prenascent earthquake telegraph its future birth and characteristics to attentive observers?

 How does an earthquake affect tectonic stress

in a region (e.g., does it simply alleviate stress

and thus reduce the likelihood of an imminent

recurrence, or can an earthquake create distortions in the regional stress field that set off

nearby followers)?

The advent of faster, more powerful computers

has aided in understanding the processes by which

crustal stresses lead to earthquakes at any given

location. Using seismological data, researchers

now model how fractures initiate and propagate as

a result of mechanical properties (e.g., frictional

strength) and stress changes at each point on the

fault. In addition, three-dimensional models of

ruptures along segmented faults are being developed to study what stops earthquakes and thereby

to estimate their magnitudes.43

Another effort to understand what controls

earthquake faulting involves laboratory studies of

the physical properties of earth materials and

physical conditions at the earthquake source, the

interactions between rock and fluid in the fault,

and nucleation and instability mechanisms.44 The

objective is to improve tools for interpreting observations of seismic and geodetic data in terms of

earthquake processes and conditions at the source.

Paleoseismology

On most faults, the time between similar large

earthquakes is much longer than the period over

which modern instruments have observed earthquakes and geodetic changes. Even in regions

where recorded history spans thousands of years,

such as the eastern Mediterranean or north-central

China, contemporary observers often could not

correlate earthquakes with specific faults.45 Thus

our knowledge of how often faults can produce

damaging earthquakes is very limited.

To learn whether or not earthquakes consistently rupture the same segment of a fault in the same

way (i.e., act as a characteristic earthquake) or follow a regular time pattern, it is necessary to extend

the modern record back long enough to encompass several similar earthquakes on the same fault.

This need led to the development of paleoseismology, a relatively new field of earth science. Researchers seek and examine evidence of sudden

coastal subsidence or uplift; fault displacement

revealed by shallow excavations; and deposits

related to liquefaction, tsunamis, or other seismically induced processes. In many cases, paleoseismic events can be dated by radiocarbon and other

techniques, although typically not with as much

precision as historical events.46

With funding from NEHRP, this type of data

collection has accelerated in the past 15 years. Paleoseismology has been particularly useful in as43 Ruth Harris, U.S. Geological Survey, Menlo Park, personal communication, Nov. 4, 1994.

44 James Dieterich, U.S. Geological Survey, Menlo Park, personal communication, Nov. 4, 1994.

45 This section is drawn from Robert Yeats, Department of Geosciences, Oregon State University, personal communication, May 7, 1995.

46 Kenneth A. Geottel, Goettel & Horner, Inc., personal communication, May 7, 1995.
Chapter 2 Understanding Seismic Hazards 157

Seismic monitoring serves several purposes: it allows determination of the location of significant earthquakes in support of emergency response and public information; it enables nuclear test ban verification;

and it supports research directed at improving basic understanding of tectonics and earthquake phenomena,

In the 19th century, knowledge of major seismicity was for the most part limited to earthquakes felt on

the continents.1 The installation and operation of seismometers in many countries, along with extensive

cooperation in exchanging data, have since permitted knowledge and illustration of global patterns of seismicity, The 1960s witnessed the establishment of a global network of seismic stations (largely with nuclear

monitoring in mind); at the same time, several regional seismic networks were established in the United

States. As of 1994, there were more than 1,400 permanent seismographic stations maintained by regional

networks 2

Two primary classes of seismometers exist today: 1) 1960s-generation equipment that provides data in

limited frequency and amplitude ranges, largely because of analog transmission constraints; and 2) new

generation broadband, high-dynamic range instruments available since 1985. The advanced instruments

and digital telemetry now enable improved representation of the phase and energy spectra of seismic

waves, essential to ground motion and earthquake processes research. With constrained resources, however, there are tradeoffs between increasing the quality or the quantity of instruments Likewise, there is

tension between providing funding for the operation and maintenance of stations and performing research

with the available data.

Seismogram of Northridge Aftershock

NOTE: Vertical component of acceleration recorded in the San Fernando Valley from a magnitude 45 aftershock of the 1994 Northridge earthquake

SOURCE: U.S. Geological Survey, 1995.

1 Bruce A. Bolt, Inside the Earth” Evidence from Earthquakes (San Francisco, CA W H Freeman and Co , 1982), p 54

2 Council of National Seismic System, “CNSS Seismic Networks and Data Centers” internet address http://www. geophys.washington.edu/CNSS/cnss.sta.html, May 11, 1995 CNSS was begun at a meeting in Denver in February 1993 by representatives from

most of the U.S. regional seismic networks and the National Seismic Network to help coordinate efforts to record and analyze seismic

data in the United States As of spring 1995, 27 institutions had formally joined the council

(continued)
58 I Reducing Earthquake Losses

National Seismic Network

In the late 1980s, the Nuclear Regulatory Commission decided to withdraw support for its networks,

located primarily in eastern states, The U.S. Geological Survey proposed to establish the National Seismograph Network (NSN), a 150-station network of modern digital stations distributed throughout the country,

to enable uniform monitoring of significant quakes and provide data for research into a variety of earthquake problems. To date, 23 NSN broadband seismic stations have been installed in the eastern United

States, with nine more stations planned. In the western United States, 16 NSN broadband stations are operating, and seven more are planned. Installation of an additional 10 to 15 cooperative NSN stations IS

possible over the next few years for the continental United States.3

NSN is not intended to perform the monitoring and research functions of the existing regional networks,

Rather, it leverages their capabilities with technology for recording broadband, high-dynamic range, threecomponent seismic data in real time and with low telemetry costs. In addition, NSN provides standardized

data manipulation procedures and a communications network that interconnects regional networks 4

3 Harley Benz, U S Geological Survey, personal communication, May 11, 1995

4 Thomas H. Heaton et al., “National Seismic System Science Plan, ” U S Geological Survey Circular 1031 (Washington, DC: U.S.

Government Printing Office, 1989), pp. 21-22

SOURCE Office of Technology Assessment, 1995

sessing earthquake potential in regions that have simplest model of the earthquake cycle is that

not been struck by a major earthquake during recorded history, such as the Salt Lake City metropolitan corridor, the San Andreas fault in

southeastern California, and the Cascadia subduction zone in the Pacific Northwest. It has also

helped to reduce uncertainty about the frequency

of major quakes in the central United States, and

to enhance knowledge of historic earthquakes in

the San Francisco Bay area.47

Earthquake Forecasting and Prediction

A longstanding objective of efforts to understand

basic geological and seismological processes is a

reliable means of predicting earthquakes.48 The

strain accumulates, is released in an earthquake,

and accumulates again—initiating another cycle.

The average length of the cycle for a certain type

of quake at a given location is called the recurrence interval, which is used to roughly estimate

the time of the next earthquake. To determine this

interval, scientists rely on seismic monitoring and

paleoseismology to obtain relationships for magnitude and recurrence.

Historical seismicity and paleoseismology

show, however, that there is great variability in the

timing, location, and magnitude of earthquakes.

The variations in earthquake characteristics on a

single fault segment or the clustering of several

47In spite of the fact that paleo means ancient, paleoseismologists study both prehistoric and historical earthquakes-in areas having short

historic records, there may be only one example of an earthquake on a given fault. Carol Prentice and Andrew Michael, U.S. Geological Survey,

Menlo Park, personal communications, June 5, 1995.

48 This report distinguishes between forecasting and prediction as follows: the former refers to estimates of earthquake potential or timing

over a period of many decades; the latter encompasses estimates of earthquake occurrence on shorter time scales (e.g., imminent—a few seconds or minutes; short-term-several minutes to days or weeks; and intermediate-term-up to several years).
Chapter 2 Understanding Seismic Hazards 159

U.S. region International counterpart

New Madrid Seismic Zone and Australia, peninsular India

eastern United States

California New Zealand, northeastern Iran, Mongolia, Turkey, Venezuela

Intermountain West North-central China, Aegean region of Greece and western Turkey

Pacific Northwest Southwest Japan, southern Chile

SOURCE Robert Yeats, Department of Geosciences, Oregon State University, personal communication, May 7, 1995

earthquakes in time indicate that the simple model

is not sufficient for many applications. Some areas

exhibit greater variability than others; typically,

these are regions of more complex geology and

plate interaction. Several U.S. metropolitan centers are located in such regions (e.g., Los Angeles,

San Francisco, and cities in the Pacific Northwest).

To improve on the simple earthquake model requires a better understanding of the processes

through which tectonic stress leads to individual

earthquakes. This entails developing models of

earthquake generation and relating these models

to things we can observe in the earth (some of

which may turn out to be earthquake precursors).

Therefore, current efforts at earthquake prediction

combine historical seismological and paleoseismological data with models of earthquake

generation, and correlate the results with measurements of geophysical phenomena.

Forecasts

In a few regions of the country, scientists have

gathered enough data to permit long-term earthquake forecasts; these are often expressed as the

probability that a certain size earthquake will occur within the next few decades, either for a single

fault (e.g., the southern San Andreas or Wasatch)

or for a region with several hazardous faults (e.g.,

the San Francisco Bay area) .49 Such probabilistic

assessments have been important in analyzing a

region’s seismic hazard, and directly support landuse planning and building code development.50

Because individual earthquakes repeat so infrequently and because there is variability between

events, these forecasts are subject to considerable

uncertainty. We can develop and test improved

models more rapidly if we also look outside the

United States for data, especially to other parts of

the world that have similar geologic settings and

have had large historical earthquakes. Table 2-4

lists these areas and their international counterparts.

Prediction

In theory, prediction could stem from improvements to the probabilistic forecasting method—

that is, through reducing uncertainties in the

assessment of earthquake characteristics and timing to permit more precise estimates. But variability in earthquake events is not the only source of

uncertainty; the probabilistic method is also hampered in areas where quakes are very infrequent or

have poor surface expression, and where geophysical and geodetic data are sparse. Intraplate

quakes, in particular, tend to have very long recur49 A probabilistic forecasting model, for example, incorporates the regional stress field, rate of crustal deformation in the vicinity Of the

fault, and strain accumulation with seismologic and geologic data.

50 Estimates of earthquake potential are also used in deterministic assessments of seismic hazards (i.e., the calculation of strong ground

motions for a specific earthquake scenario and site); these are frequently used in building design and the construction of seismically resistant

structures.
60 | Reducing Earthquake Losses

rence times (e.g., thousands of years), and few

have surface expression.

Thus earthquake prediction may hinge on interpreting certain warning signs rather than enhancing current models of the seismic cycle. As a first

step, it is essential to verify whether or not such

signs exist. Box 2-6 discusses research questions

related to earthquake prediction.

❚ Foretelling Earthquake Effects

In addition to determining earthquake potential,

an equally important task for the earth science

community is to give planners and engineers precise information on what earthquakes will actually do to the earth’s surface that threatens the built

environment. Earth science R&D with more immediate application to mitigation has historically

been overshadowed by the basic research disciplines, but is now receiving increased emphasis (a

breakdown of funding levels is given in appendix

B). This applied research is of great importance

for two reasons.

First, because earthquake effects on the earth’s

surface are complex, improving the seismic resistance of lifelines, buildings, and their contents requires detailed knowledge of the physical forces

they will encounter. Second, the initial expenses

of some mitigation measures are such that at-risk

communities may have difficulty implementing

them. The use of broad-brush, regionwide mitigation measures is often constrained by political and

economic concerns (see chapter 4). Research that

can identify locations of extreme danger and areas

of relative safety can thus allow communities to

target limited resources to where they will do most

good.

This work includes the fields of strong-motion

studies and seismic zonation (and its subset, microzonation).51 Its objective is to examine—and

quantify where possible—how seismic waves interact with particular aspects of local geology and

geography to produce potentially damaging effects, including ground shaking, soil amplification, liquefaction, and tsunamis. The following

discussion explains related studies and their applications in more detail.

General Ground Shaking

To design buildings and other structures that resist

seismic damage, the engineering community requires quantitative estimates of the accelerations,

velocities, and displacements that will occur in future earthquakes. Producing such estimates requires knowledge of:

 future earthquake magnitude;

 the location, orientation, and size of the likely

earthquake fault;

 the attenuation characteristics of geologic material lying between the earthquake location

and the area of concern (to determine how rapidly seismic waves decay with distance from

the epicenter); and

 the general soil characteristics of the region.

This work is partly theoretical and partly empirical; it typically involves the correlation of laboratory predictions with data recovered from

strong-motion seismometers in real-world earthquakes52 (see box 2-7). Useful data can also be obtained by temporary regional-scale seismic

networks deployed in an earthquake’s aftermath to

record the effects of aftershocks.

51 Strong-motion studies focus on the shaking effects that seismic waves impose on the earth’s surface, while zonation is a broader field that

incorporates such indirect earthquake hazards as landslides and tsunamis, as well. Microzonation is hazard assessment on the scale of a town or

city block.

52 Strong-motion devices differ from traditional seismometers in that they can record the strong, violent ground motions from a nearby

earthquake without failing or going off-scale (traditional observatory-grade seismometers are sensitive instruments designed to detect the faint

tremors from distant seismic events and cannot handle strong shocks). Gathering strong-motion data has thus historically meant the deployment

of specialized instruments for the task. However, recent technical developments have allowed some modern seismometers to function both as

strong-motion instruments and as observatory devices, and they are increasingly used in many of the newest seismic networks.
Chapter 2 Understanding Seismic Hazards 161

To date, programs directed at predicting earthquakes have had mixed success, The central questions

include: 1 ) are there specific physical conditions that Indicate the location, timing, and size of future earthquakes; 2) are current research programs adequately designed to capture and permit assessment of potential precursors?

■ Is there a recognizable pattern to earthquakes?

Through statistical analysts of worldwide earthquake occurrences, one can estimate the frequency of

different magnitude quakes across the globe. The monitoring of global seismicity also makes it clear that

certain areas are much more prone to quakes than others—90 percent of the world’s earthquakes occur on

the boundaries of large tectonic plates

Along a single plate boundary, however, there can be considerable variability in the size and frequency

of significant earthquakes. For example, parts of the San Andreas fault accommodate the relative motion of

the North American and Pacific Plates without earthquakes (i.e., through aseismic slip); other sections of

the fault have experienced several large or major quakes during recorded history. In general, intraplate

earthquake sources and processes are even less well known Thus, a better understanding of the relationships among plate tectonics, regional stresses, and earthquake sources is needed.

■ Is an earthquake’s size “known” at the time of its initiation?

Scientists are making progress in understanding earthquake genesis and growth, although there IS not

yet consensus on whether the eventual magnitude of the quake is random or somehow programmed into

the surrounding rock, Recent observations of earthquake sources using advanced seismographic instruments, however, show that earthquakes Initiate with a distinctive seismic nucleation phase and that the size

and duration of the nucleation phase appear to scale with the eventual size of the earthquake. ’ These new

and somewhat controversial results suggest that conditions favoring the growth of large, potentially destructive earthquakes are fundamentally different from those that lead to more common, smaller events, If

so, careful geologic and geophysical monitoring might someday detect the conditions that signal the imminent risk of a large earthquake.

Local geology (and topography) may also have a role in whether larger, less frequent quakes (or smaller, more frequent ones) are to be expected on a fault 2 Advanced models of rupture propagation, additional

geophysical data, and additional seismological data from newer broadband, high-dynamic range instruments will likely aid in understanding how surficial and subsurface fault characteristics affect rupture and

maximum magnitude.

● Does the state of stress that causes an earthquake to initiate and a fault to rupture betray itself

through characteristic signals?

The standard approach to developing a prediction capability hinges on the earth’s providing recognizable signals of impending quakes. Ideally, much as we have come to associate certain symptoms with the

onset of a cold, scientists could detect reliable Indicators of an earthquake’s occurrence in advance of the

event itself.

1 W L Ellsworth and G C Beroza, “Seismic Evidence for an Earthquake Nucleation Phase, ” Science, VOI 268, 1995, p 851

2 Scientists look for the presence of rough patches in the fault (asperities) through analysis of seismograms, physical separation

(e.g., step-overs) between fault segments, or other geologic barriers to the spread of the rupture zone

(continued)
62 I Reducing Earthquake Losses

Theoretical and laboratory studies indicate there should be a preliminary phase prior to rupture. Potential

earthquake precursors include: foreshocks (as material starts to fail under the extreme stress or strain),

changes in the groundwater table (these occur when water-bearing pores in the rock start to deform under the

stress) and other hydrologic or hydrothermal phenomena, deformation of the earth’s surface, changes in the

rock’s electrical conductivity or magnetic properties, and changes in seismic wave properties through the

area in question. In the past, such phenomena have been observed in the field, but not consistently.3

Broad efforts to Identify potential precursors are being pursued in China, Japan, and the former Soviet

Union through extensive monitoring of seismicity, crustal deformation, and a variety of other phenomena. Chinese scientists were able to predict the 1975 M7.4 quake in Haicheng and the August 1976 M7.2 Songpan

earthquake. 4 However, they were unable to predict the July 1976 Tangshan earthquake (M7.8), which killed

hundreds of thousands. In Japan, public warning was achieved for the 1978 lzu-Oshima earthquake (M7).5

Japan’s monitoring and prediction program focuses primarily on the region surrounding Tokyo, which has the

highest seismic risk. The Kobe locale, assigned a very low hazard, received little prediction attention.

It is important to note that Japan’s monitoring program is directed at subduction zone earthquakes and

may not be applicable to the strike-slip boundary on the U.S. West Coast. 6

Earthquake Prediction in the United States

The first U.S. effort directed at earthquake prediction was located near the central California town of

Parkfield, adjacent to the San Andreas fault. The Parkfield prediction experiment was begun in 1985 after

analysis of previous earthquake occurrences on a particular fault section indicated that a repeat event

would occur near the end of the decade. 7 The expected “characteristic earthquake” did not happen within

the prediction window.

Further analysis showed that, while the successive repeat of similar (but not identical) quakes might be

expected on individual fault sections, the amount of time between them may be highly variable Confidence

in predictions based on estimations of recurrence intervals has decreased; scientists are more sanguine

about the possibility of identifying one or more of the “red flags” described above. 8

Today, the Parkfield experiment operates 21 instrument networks to record pre-earthquake phenomena

(e.g. strain transients, electromagnetic signals); five of these networks are monitored in real time Ten

additional networks are in place to record strong ground motion, co-seismic slip, and liquefaction 9

3 Paul Silver, Department of Terrestrial Magnetism, Carnegie Institution, personal communication, Apr 5, 1994

4 Cinna Lomnitz, Fundamentals of Earthquake Prediction (New York, NY: John Wiley & Sons, Inc., 1994), pp. 22, 29-30 Some

argue that the Haicheng quake was easy to predict because there were many foreshocks the day before the main shock

5 Evelyn Roeloffs and John Langbein, “The Earthquake Prediction Experiment at Parkfield, California, ” AGU Reviews of Geophysics, vol. 32, No 3, August 1994, p 315

6 The Japanese program has also been the subject of much criticism for its expense, lack of openness, and lack Of results. See,

e g , Robert J Geller, “Shake-up for Earthquake Prediction, ” Nature, vol. 352, No. 6333, July 25, 1991, pp. 275-276

7 Parkfield has experienced moderate quakes six times since 1857. In 1985, on the basis of this sequence, the recurrence interval

for M6 quakes near Parkfield was estimated to be about 22 years, and it was estimated with 95 percent confidence that another similar

event would occur before 1993 Roeloffs and Langbein, see footnote 5, p. 315, citing W.H. Bakun and A G Lindh, “The Parkfield,

California, Earthquake Prediction Experiment, ” Scier_rce, vol. 229, 1985, pp. 619-624.

8 Silver, see footnote 3

9 Roeloffs and Langbein, see footnote 5.
Chapter 2 Understanding Seismic Hazards 163

Assessing Prediction Feasibility

For prediction to be feasible, however, scientists must be able not only to recognize the red flags, but

also to determine the relationship between these precursors and succeeding earthquakes. In addition, the

red flags must have some predictive power; that is, there must be a sound correlation between their occurrence and the subsequent occurrence of significant earthquakes.10 

According to some scientists, while the current monitoring program at Parkfield may yield useful data

for that specific spot, it is not comprehensive enough to verify whether or not prediction is feasible.

Instead, they advocate a more extensive program to monitor multiple types of potential precursors throughout the San Andreas fault zone. New observation techniques (e. g., space-based geodetic surveys and

Imagery of crustal deformation) could provide the necessary broad coverage and complement in situ monitoring and fault studies.

Given the complexity of such an undertaking, as well as the relative infrequency of damaging U.S.

earthquakes, results from this effort might not be expected for another few decades.

10 silver, see footnote 3

SOURCE Off Ice of Technology Assessment, 1995.

Early Warning

Advances in seismometers and telecommunications, along with automated analysis of earthquake events, may soon permit early warning of

seismic waves capable of producing strong

ground motion. Because electronically transmitted information travels at a much faster rate

than seismic waves travel through the earth, realtime warning of severe shaking approaching a

populated area or lifelines will be possible given

monitoring systems that can automatically determine a quake’s location and magnitude and estimate the strong-motion characteristics within a

few seconds.53 Early warning systems hold the

potential for automated response during an earthquake and more rapid, effective response after the

shaking stops.

Amplification Effects

Engineers and planners within specific communities also must be aware of the possibility of localized, unusually high amounts of ground shaking.

These “hot spots” can result from simple soil amplification, in which the presence of soft soils and

sediments at the earth’s surface significantly increases the amplitude of passing seismic waves

(see figure 2-8).

The collection of ground motion records from

recent large California quakes and their aftershocks, as well as from recent events in Mexico

and Japan, has aided in understanding site effects

in these areas.54 However, records for other areas

of the United States are very limited. In addition,

significant geotechnical modeling is still needed

53 Post-earthquake notification systems have been operating in southern California since 1991 and in northern California since 1993. System operators expect to achieve early warning capabilities within a few years.

54 Stephen Hartzell, U.S. Geological Survey, Earthquake and Landslide Hazards Branch, personal communication, Oct. 20, 1994.
64 I Reducing Earthquake Losses

Beside the seismometer, another essential tool for defining the impact of a quake is the strong-motion

accelerograph, typically housed in or near buildings, dams, and other critical engineered structures. Strong

motion is used to mean ground motions that are sufficiently large to cause damage to structures; a strongmotion accelerograph is intended to record these large motions without signal saturation. The data generally are used for engineering purposes and, until recently, the instruments were usually triggered only by

events of a minimum magnitude (e.g., M4.5 for local events or higher for distant quakes).

The development of regional seismographic networks began in the 1960s in response to the need to

learn more about the distribution of seismicity with areas of recognized earthquake hazards. Because the

primary objective of their implementation was the construction of a catalog of earthquake activity with high

spatial resolution, the seismometers were adjusted to record smaller, more numerous earthquakes. This,

combined with the use of analog data telemetry to meet high sample rate requirements and an emphasis

on high-frequency ground motions, limited the effective dynamic range of the monitoring networks. As a

result, the recording of strong ground motions was largely sacrificed.

Now, digital strong-motion instruments are being Integrated into seismic observatories that record both

weak and strong ground motions.

The majority of strong-motion networks are located in the western states; with these instruments, scientists and earthquake engineers have obtained a fairly extensive strong-motion data set for the southwestern United States. Few records exist for other parts of the country and, more importantly, there are no nearfield records from damaging quakes in U.S. urban centers. This means that scientists and engineers still

lack empirical knowledge of the effects of earthquakes that occur directly beneath densely populated

areas. ’

1 The 1994 Northridge quake occurred in a largely suburban area, and its largest motions were focused toward less populated

areas The ground motions in downtown Los Angeles produced by a quake on the buried Elysian Park thrust fault, for example, would

likely be much larger than those experienced above the source of the Northridge quake Likewise, the 1989 Loma Prieta quake occurred several miles from heavily populated centers in the San Francisco Bay area.

SOURCE: Office of Technology Assessment, 1995, based on Thomas H. Heaton et al , “National Seismic System Science Plan,” U S

Geological Survey Circular 1031 (Washington, DC: U.S. Government Printing Office, 1989)

to address several facets of site response, includ- soils, and clays, on which most of the country’s uring soil properties, stratigraphy, and ground mo- ban centers are built) trap, accumulate, and amplitions that occur in the immediate vicinity of a fy passing seismic waves (see box 2-8); and 2)

fault. 55 ridge effects, in which topographic features such

Other factors in unusual ground shaking are: 1) as hills and valleys can focus seismic waves tobasin effects, in which sedimentary basins (large, gether in the manner of a lens.56

bowl-shaped deposits of river or lake-borne sands,

55 Examples are: nonlinear response of soft, weak soils; deep basin response; deep cohesive sites and shallow, stiff soils; two- and three-dimensional topographic and stratigraphic effects; and near-field motions and spatial incoherence. Ray Seed, Earthquake Engineering Research

Center, University of California, Berkeley, personal communication, Nov. 3, 1994.

56 Amplification and basin effects were largely responsible for the unusual amount of devastation wrought in the Mexico City earthquake of

1985, as well as for damage to the Marina District of San Francisco in the 1989 Loma Prieta quake. Ridge effects in the Loma Prieta event are

thought to have been responsible for vertical accelerations in excess of 1 g in certain severely damaged neighborhoods.
Chapter 2 Understanding Seismic Hazards 65

Predicting amplification effects is in theory

straightforward, since the scientific principles involved are well understood. However, accurate estimates require detailed knowledge of local

geology (which typically demands a special effort), as well as specific predictions of the future

earthquake’s source characteristics (i.e., fault rupture characteristics and the consequent nature of

the initial seismic waves).

Ground Failure

Combining knowledge of the potential for strong

shaking and of local geology and soil conditions

yields an improved capability to identify the potential for liquefaction, landslides, and other

forms of ground failure. When water-saturated

soils and sediments turn into a quicksand-like

slurry during extended shaking, they lose the ability to bear loads, thus causing even seismically

resistant buildings and structures to fail at the

foundation. Lateral spreading or permanent

ground displacement also can cause great damage

to buried utilities or port facilities. These phenomena are of particular concern to planners and local

policymakers, because sites prone to such failure

may require extraordinary preventive measures or

relegation to less vulnerable forms of land use.

Geographical Information System (GIS) tools

have been increasingly utilized in assessing these

hazards and in analyzing related risks to special

facilities or structures. Primarily a research tool

today with respect to earthquake hazards, GISbased maps can be readily converted to a larger

educational-or policy—tool as well.57

In addition, systems have been proposed for

both northern and southern California that will incorporate knowledge of a quake’s location, size,

and faulting mechanism into preexisting databases on shallow soil structure and the built environment. 58 Their objective is to quickly map the

zones with most severe ground motion, which will

indicate where emergency managers should look

0.2

A. Rock, Yerba Buena Island

0.15

0-

Q

-0.05 

-0.1 I

Peak acceleration, 0.07 g 

I

-0.15 

-0.2 ,—r.——--—— -

0 5 10 15 20 25 30 35 40

Time, in seconds

B. FiII and bay mud, Treasure Island

0.15

0.1 I

0.05

I

0-

-o.05-

-0.1-

-0.15 Peak acceleration, 0.16 g

O 5 10 15 20 25 30 35 40

Time, in seconds

NOTE” Recorded horizontal ground motion (east-west direction) from

the 1989 M7.1 Loma Prieta earthquake,

SOURCE: U.S. Geological Survey, 1995

for the most damage and should direct response

teams.

Tsunamis and Seiches

In addition to knowledge of the hazardous effects

described above, coastal communities also require warnings of the possibility of tsunamis and

57 Arthur C. Tarr, U.S. Geological Survey, Earthquake and Landslide Hazards Branch, personal communication, Oct. 21, 1994.

58 Barbara Romanowicz, Seismic Research Center, University of California, Berkeley, personal communication, NOV. 3, 1994.
66 I Reducing Earthquake Losses

Most of the large urban areas in the United States have developed on sediment-filled basins, which can

strongly modify the ground motion from an earthquake. ’ It is believed that the shape and material properties of a sedimentary basin allow it to focus and collect seismic waves.2 The result is large-amplitude surface waves that reverberate long after the rupture itself has ceased. Until recently, however, models of the

earth’s structure and wave propagation could not represent these conditions.

Under NEHRP, the U.S. Geological Survey is applying new three-dimensional modeling techniques to

the case of complex propagation effects for the San Bernardino Valley east of Los Angeles, through which

the San Andreas fault passes. The simulated effects include high ground velocities in localized portions of

the basin, which could pose significant risk to structures with natural periods of one second or longer (e.g.,

buildings of 10 or more stories, some highway overpasses, and elevated pipelines).3 Similar studies are

under way for the San Francisco Bay area and Washington State’s Puget Sound region.

1 Stephen Hartzell, U.S. Geological Survey, Earthquake and Landslide Hazards branch, personal communication, Oct 20, 1994

2 Thomas H, Heaton and Stephen H. Hartzell, “Earthquake Ground Motions, ” Annual Review of Earth PIantary Science, voI. 16,

1988, p. 127, citing J A. Rial, “Caustics and Focusing Produced by Sedimentary Basins, Applications of Catastrophe Theory to Earthquake Seismology, ” Geophysical Journal of the Royal Astronomical Society, vol. 79, 1984, pp 923-38.

3 Arthur Frankel, “Three-Dimensional Simulations of Ground Motions in the San Bernardino Valley, California, for Hypothetical

Earthquakes on the San Andreas Fault, ” Bulletin of the Seismological Society of America, vol. 83, No. 4, August 1993, p 1021

SOURCE. Off Ice of Technology Assessment, 1995.

seiches. Research into these hazards-which completely undetected.59 Given these characterisseeks to understand why they are generated by

some earthquakes and not others—blends the

scientific fields of seismology and oceanography.

Such research has a considerable international

component (although tsunamis and seiches do

take place in the United States, considerably more

experience has been gained by Japan and other

countries of the far Pacific Rim) and is frustrated

by the unusual physical characteristics of the phenomena. Tsunamis, for example, exist in the open

ocean as extremely fast, extremely broad, but extremely low waves that can pass beneath ships

tics, specialized tsunami detection equipment is

necessary both for research and for establishing

early warning systems for coastal communities. 60

The National Oceanic and Atmospheric Administration operates the U.S. tsunami warning system.

A common thread in all these applied research

efforts is that they require collaboration between

specialists in the traditional seismic research community and practitioners in other earth science and

engineering disciplines. Moreover, the work cannot be accomplished purely through theory or lab59 The danger of tsunamis is that, although extremely low in the open ocean (only inches high), they are long enough to contain a considerable amount of water (tsunami waves can stretch a hundred miles crest to crest), and fast enough to propel that water far inland. Speeds of

hundreds of miles per hour are common. In a damaging tsunami strike, the incoming wave slows down as it approaches land. As it slows, the

back of the wave catches up with the front, the wave height builds to many tens of feet, and the wave ultimately washes ashore as a huge surge of

water.

60 Because tsunami waves are so broad and low, their detection in the open ocean requires devices akin to tide gauges (i.e., instruments that

can detect the passage of an open-ocean tsunami amid normal wind-driven waves).
Chapter 2 Understanding Seismic Hazards | 67

oratory experiments; gathering detailed geologic

information on each region or locality of interest

requires a concerted effort.6l

For example, the U.S. Geological Survey prepares maps of seismic hazards on national and regional scales, using a variety of data sources and

modeling techniques (see figure 2-9). Maps of expected ground shaking are converted by the engineering community into design maps that reflect

current engineering analyses; they form the

foundation for model seismic codes. In addition,

regional hazard maps support state and local landuse planning efforts, and can pinpoint areas where

further study is warranted.

SUMMARY AND KEY FINDINGS

Earthquake hazards vary widely across the United

States. The most active seismic regions in the

United States are Alaska and California; their high

seismic it y stems from proximity to the boundaries

between shifting segments of the earth’s crust.

However, few parts of the United States are immune to quake hazards. Significant earthquakes

have occurred in the Pacific Northwest, in the central United States, and along the east coast.

Earth science research, in which NEHRP has

played a key role, has advanced significantly our

understanding of U.S. seismic hazards. It is now

possible to estimate the likelihood of future earthquakes for a few areas (the San Francisco Bay and

greater Los Angeles areas, where many years of

study have helped to reduce uncertainties; Utah’s

Wasatch fault zone; and the New Madrid Seismic

Zone). In the near future, scientists maybe able to

do the same for other regions of the United States.

The importance of local soil conditions and

other factors that influence the type and degree of

damage an earthquake can cause (e.g., soil amplification and landslides) are now recognized and

better understood. It is now possible to produce

detailed maps showing specific hazards resulting

Valdez, Alaska, waterfront after tsunami caused by 1964 

Good Friday earthquake.

from local soils, and provide more detailed and accurate expected ground motion information for

use in building design and model code development. Within a few years, researchers expect to be

able to provide real-time warnings of approaching

strong shaking.

Despite the numerous advances, however, significant uncertainties and knowledge gaps remain. Scientists are far from able to determine the

specific time, location, and magnitude of future

earthquakes. Among the key unknowns are questions about the constitutive properties of faults,

the interactions of different fault systems, and the

mechanisms of rupture. Additionally, in many

areas of the country, the location of faults capable

of producing damaging earthquakes is still not

known, nor is the likelihood of these earthquakes

or the extent of their hazardous effects.

There are many societally useful directions for

future earthquake-related earth science research.

A key issue is how to strike the appropriate balance between types of research efforts and among

different geographical areas, given both financial

and time constraints. As with many research-in61 The effort to gather such information (i.e., geologic and geophysical mapping) is often carried out for other purposes by USGS and by

private concerns such as the petroleum and mineral exploration industries. The oil and mineral industries are very competitive; companies are

often understandably hesitant to make data gathered at considerable expense available to competitors.
68 I Reducing Earthquake Losses

Seismic hazard maps

> Design value maps for building codes

National and regional

Quantify the rates of occurrence,

magnitudes and probable locations

■ Analyze historical seismicity

■ In the western United States, determine

recurrence rates and magnitudes of large

prehistoric earthquakes on faults.

Quantify the ground motions that will be

produced by these earthquakes

■ In the central and eastern United States,

study pre-historic quakes with paleoliquefaction

■ Evaluate geologic structures associated

with seismicity.

■ Estimate maximum magnitudes from

geologic structures.

■ Determine the ground motions as a function

of magnitude and distance.

■ Analyze seismograms to assess source, site,

and path effects.

■ Assess regional variations in ground motions

(e.g., between western and central or eastern

United States).

■ Map geology to determine site amplification.

SOURCE U S. Geological Survey, 1995.

tensive efforts, it is difficult to quantitatively assess the value of different activities; determining

the balance between applied research directed at

near-term results and longer term research is a

political, not merely a scientific, challenge. Even

within the earth science community, tension exists

over how to divide resources between expanding

the fundamental understanding of quake phenomena and concentrating on mapping hazardous site

conditions in areas where damaging seismicity

has already occurred.

Decisions on how to allocate earth science research funds should be made in the context of the

goals of the earthquake program (discussed in

chapter 1). However, several research areas clearly deserve attention:

■ Microzonation. To better assess the overall

risk posed to inhabitants and the built environment, analysis of the potential for strong shaking or ground failure is needed on finer scales.

This requires not only the application of improved models of earthquake potential and expected shaking, but detailed mapping of

near-surface geology and site conditions. Such

microzonation studies have been completed in

only a few areas of the United States. Thus, we

have an incomplete picture of the probability of
Chapter 2 Understanding Seismic Hazards | 69

significant hazards near populated areas or critical facilities for all but the most intensely studied zones (i.e., the San Francisco Bay area and

greater Los Angeles region). Additional emphasis should be placed on microzonation in

urban areas and around critical facilities where

long-duration, strong shaking is expected.

 Earthquake potential. New technologies and

practices have enabled significant additions to

the body of knowledge required to understand

the potential for earthquakes in different areas.

Paleoseismology permits more reliable estimates of the magnitude and dates of prior earthquakes, especially in areas where damaging

earthquakes have very long recurrence times.

This information is essential to gauging the

likelihood of future damaging events within a

decades-long time frame.

 Satellite-based geodetic techniques have revolutionized the observation and modeling of

crustal deformation, which contributes to assessments of crustal stress and strain. This information supports long-term forecasts of

earthquake potential. In addition, further enhancements to the scope and accuracy of these

techniques could provide the foundation for

new imaging methods that, akin to weather

forecasting, facilitate reliable earthquake prediction.

 Geographic focus. Because of its frequent

damaging earthquakes, California is the test

bed for the development of many current theories and techniques. However, some of these

may not be readily adapted to the Pacific Northwest or to the central and eastern United States.

Additional research and data collection specific

to these latter areas should be considered to determine what distinguishes the nature of the

hazards and to support the application of existing tools.

 International focus. Fortunately for those

who experience damaging earthquakes, the

events are few and far between. This leaves the

scientific community at a disadvantage, however, with respect to opportunities to incorporate data into the seismic record and evaluate

theoretical models of seismic phenomena.

Field investigations and analyses of data from

earthquakes that occur outside our borders are

crucial to understanding similar U.S. seismic

hazards (e.g., subduction and intraplate quakes

that have occurred here rarely).

 Knowledge transfer. It is essential to maintain

efforts to make new knowledge and tools readily available to potential users. In recent years,

the earth science research community and

NEHRP research agencies have put increased

emphasis on knowledge transfer to professionals and the general public. These efforts, although difficult to evaluate, are crucial to

ensuring that research results help to accelerate

the pace of earthquake mitigation throughout

the country.
The Built

 Environment

arthquake hazards exist throughout the United States. The

primary hazard associated with earthquakes is ground

shaking, which damages and destroys buildings, bridges,

and other structures. Ground shaking also causes liquefaction, landslides, and other ground failures that also damage

and destroy structures. This damage can cause massive immediate financial losses, casualties, disruptions in essential services

such as water and electricity, and severe long-term economic and

social losses. Although the location, timing, and magnitude of future earthquakes are uncertain, there is little doubt that potentially

damaging earthquakes will strike U.S. metropolitan areas in the

next few decades.

Although earthquakes are unavoidable, the losses they cause

are not. This chapter reviews technologies and practices to reduce

the societal losses1 of earthquakes. The focus is on the built environment—the buildings, bridges, pipelines, and other structures

that bear the brunt of earthquake damage. The chapter first discusses deaths and injuries from earthquakes, focusing on what

causes them and how they can be reduced. This is followed by a

discussion of buildings—how they are damaged by earthquakes,

and what technologies and practices are available to increase the

seismic resistance of both new and existing buildings. Technologies for reducing damage to lifelines, such as bridges, water and

sewer systems, and energy systems, are then reviewed. Finally,

1 Damage refers to the direct financial costs of earthquakes. Losses denotes all of the

societal effects of earthquakes, including deaths, injuries, direct financial costs, indirect

costs (e.g., those resulting from business interruptions), and social impacts such as increased homelessness. Reducing damage by strengthening the built environment will reduce losses as well.

| 71
72 I Reducing Earthquake Losses

1980

1980

1981

1981

1982

1983

1983

1985

1985

1986

1987

1988

1988

1988

1989

1989

1989

1990

1990

Algeria

Italy

Iran

Iran

Yemen

Japan

Turkey

Chile

Mexico

El Salvador

Colombia, Ecuador

Nepal, India

Burma, China

Armenia

West Iran

U.S.—California

Australia

Iran

Philippines

TOTAL

7.7

7,2

6.9

7.3

6.0

7.7

6.9

7.8

7.9

5.4

7.0

6.6

7.0

7.0

5.8

7.0

5.6

7.7

7.8

3,500

3,000

3,000

1,500

2,800

107

1,342

177

9,500

1,000

1,000

1,450

730

25,000

90

63

1 3

40,000+

1,700

~96,000

SOURCE: Bruce A. Bolt, Earthquakes (New Yorkl NY: W. H. Freeman

and Co., 1993), pp. 272-273,

the chapter discusses key research needs for ensuring that the built environment is well protected

from future earthquake damage.

CASUALTIES

❚ Deaths

A single earthquake can cause thousands of deaths

and tens of thousands of injuries. As shown in

table 3-1, in just 11 years-1980 to 1990-earthquakes killed almost 100,000 people worldwide.

About two-thirds of these deaths occurred in just

two catastrophic earthquakes-25,000 in Armenia in 1988 and 40,000 in Iran in 1990.

The historical record of U.S. earthquake fatalities is less unfortunate. About 1,200 people have

died in U.S. earthquakes since 1900 (table 3-2).

Most of these earthquakes occurred in regions that

were, at the time, sparsely populated; so the low

fatality figures for 1900 to 1950 earthquakes are

not surprising. However, even those earthquakes

occurring since 1950 in heavily populated areas of

California have had relatively low fatalities, largely because many of its buildings and other structures are built to resist seismic collapse. 2

Casualties from future earthquakes are very uncertain. In California, most deaths from future

earthquakes will likely be caused by the collapse

of older, seismically vulnerable structures. One

estimate found that a repeat of the 1906 San Francisco earthquake would cause 2,000 to 6,000

deaths. 3 In the Pacific Northwest and the eastern

United States, the potential for large numbers of

deaths may be higher than in California. Although

the probability of a major earthquake is relatively

low, the building stock is more vulnerable, as even

new structures often do not use known technologies and practices to reduce seismic damage.4 One

study found that a large earthquake striking the

New Madrid region of the central United States

would cause 7,000 to 27,000 deaths.5

Deaths that occur in earthquakes are due largely

to the collapse of structures. In Armenia, most of

the deaths were caused by people being crushed

under collapsing concrete buildings. All but one

of the deaths in the Loma Prieta earthquake were

2 There is an element of luck here as well. The Loma Prieta earthquake, for example, struck during the World Series baseball game when the

roads were relatively empty. Fatalities would have been in the hundreds, perhaps higher, if traffic levels were at more typical weekday levels.

3 See “’Repeat’ Quakes May Cause Fewer Deaths, More Damage,” Civil Engineering, November 1994, pp. 19-21.

4 As noted in chapter 1, many states in lower risk areas do not have or do not enforce seismic building codes for new construction.

5 National Academy of Sciences, The Economic Consequences of a Catastrophic Earthquake, Proceedings of a Forum, Aug. 1 and 2, 1990

(Washington DC: National Academy Press, 1992), p. 68.
Chapter 3 The Built Environment 173

Damages

Year Location Deaths (million $1994)

1906

1925

1933

1935

1940

1946

1949

1952

1952

1959

1964

1965

1971

1979

1983

1987

1989

1992

1992

1993

1993

1994

TOTAL

San Francisco, California

Santa Barbara, California

Long Beach, California

Helena, Montana

Imperial Valley, California

Aleutian Islands, Alaska

Puget Sound, Washington

Kern County, California

Bakersfield, California

Hebgen Lake, Montana

Anchorage, Alaska

Puget Sound, Washington

San Fernando, California

Imperial County, California

Coalinga, California

Whittier Narrows, California

Loma Prieta, California

Petrolia, California

Landers l California

Scotts Mills, Oregon

Klamath Falls, Oregon

Northridge, California

KEY: n/a = not available.

SOURCE: Office of Technology Assessment, 1995.

due to structural failure.6 Other earthquakes generally show the same pattern: people are killed in

earthquakes when structures collapse. The second major cause of death in earthquakes is fire. In

the 1923 Tokyo earthquake, for example, many of

the 143,000 deaths were caused by the firestorms

that occurred after the earthquake.7

Further reductions in fatality levels will come

largely from incorporating seismic design prin700

1 3

120

4

8

n/a

8

1 2

2

28

131

8

65

n/a

0

8

63

0

1

n/a

2

57

1,225

6,000

6 0

540

4 0

7 0

200

220

350

60

n/a

2,280

7 0

1,700

6 0

5 0

450

6,870

7 0

100

3 0

1 0

20,000

39,160

ciples into new construction (this is not done in

many areas of the United States), retrofitting existing structures to improve their seismic resistance, and ensuring adequate fire and emergency

response.

❚ Injuries

Earthquake-related injuries, in contrast to deaths,

often result from nonstructural damage. Damages

6 M. Durkin and C. Thiel, “Improving Measures To Reduce Earthquake Casualties, “ Earthquake Spectra, vol. 8, No. 1, February 1992,

p. 98.

7 Bruce A. Bolt, Earthquakes (New York, NY: W. H. Freeman and Co., 1993). PP. 2197271.

8 This report uses retrofitting to mean adding seismic resistance features, such as bracing, to an existing building to reduce the damage if an

earthquake occurs. Some reports use the term rehabilitation instead.
74 I Reducing Earthquake Losses

Percent of

Source Injuries

Hit by falling object 1 3

Hit by overturning object 1 1

Thrown into object 1 8

Fall-related injuries 27

Strained taking evasive action 7

Structural collapse 5

Other 1 9

SOURCE: M. Durkin and C. Thiel, “lmproving Measures To Reduce

Earthquake Casualties, ” Earthquake Spectra, vol. 8, No. 1, February

1992, p 99.

can occur, and people in or near buildings can be

injured, even when there is no structural failure. In

Loma Prieta, for example, 95 percent of the injuries did not involve structural collapse (table 3-3).

These injuries were caused by falls, being struck

by falling or overturned objects, or being thrown

into objects.

Some simple, low-cost measures that can reduce these injuries include anchoring bookcases

to walls, using chains to secure books in bookcases, securing kitchen appliances to the floor,

bolting computers to desks, and tying lights to

ceilings.

DAMAGE TO BUILDINGS

When the ground moves in an earthquake, the

basement and the first floor will move with it. The

top floor, or in a multistory building the upper

floors, however, tend to stay put because a building is not perfectly rigid. The movement of the

bottom of the building relative to the top puts great

stress on the walls. The stress and resulting damage vary depending on the building itself. A simple wood house on a concrete foundation maybe

knocked off its foundation in an earth quake, because the foundation moves with the ground but

the house is left behind. A three-story brick building can be turned into a pile of rubble because the

bricks are not rigidly attached to each other; the

walls collapse outward leaving the floor unsupported. A tall steel-framed building may show

little or no damage, because steel bends and sways

to absorb the movement of the lower floors.9

The most dramatic, widely feared, and best understood type of damage is collapse (also called

structural failure)-destruction of an entire building by an earthquake, often killing most of its occupants. A second type of damage is structural

damage— broken or twisted beams, failure of

structural members, and other damages that leave

a building standing but often unsafe. In some

cases costs of repair approach those of replacement. Nonstructural damage+ racks in walls,

broken water pipes, broken windows—is rarely

life-threatening but is often dauntingly expensive

to repair. A final type of damage is contents damage--computers sliding off desks, pictures

knocked off the wall, dishes smashed, merchandise tossed off shelves in stores, and so on. A useful rule of thumb is that contents are typically

worth about 50 percent of the cost of the building

Earthquakes can severely damage buildings.

9 However, the 1994 Nothridge earthquake resulted in unexpected damage to steel buildings, which is discussed later in this chapter.
Chapter 3 The Built Environment 175

Magnitude Damage (percent of buildings)

6.0-6.5 7.5-8.0

Distance to fault (miles) Minor only Nonstructural Structural Collapse

30 5 0 10-40 1-5 <1 0

5 4 0 35-45 10-30 <5 <1

1 30 25-40 20-40 3-10 <2

— 3 5-25 40-70 10-30 <5

NOTE: These estimates are for new buildings that meet the 1991 Uniform Building Code; they do not apply to existing

building stock.

SOURCE: Adapted from Earthquake Engineering Research Institute, “Expected Seismic Performance of Building s,”

February 1994, p. 15.

itself. 10 Therefore, damage to contents, although

rarely life-threatening, can be a significant expense and can cause many injuries as well.

After an earthquake, one typically finds many

buildings with nonstructural damage and progressively fewer buildings with greater damage. The

degree of damage tends to increase as one moves

closer to the fault (see table 3-4).

The type and amount of building damage

caused by an earthquake depend on several factors. Liquefaction, in which the soil loses its ability to support weight, can cause a building to sink

or topple. Ground-shaking damage will vary depending on the magnitude and frequency of the

shaking. In general, long, slow ground movement

is more damaging to taller buildings because the

ground movement is closer to the building’s natural frequency. In contrast, short, rapid ground

movements are generally more damaging to shorter buildings. The design and materials used in the

building are important as well. Buildings with

carefully designed bracing, reinforcements in

concrete columns, tightly connected walls and

floors, and other seismic design features can ride

out even large earthquakes; but those designed

without consideration of seismic forces are likely

to be damaged. Finally, the material used in

construction (e.g., unreinforced masonry, wood,

and steel) has a strong influence on a building’s response to an earthquake (see box 3-l).

❚ New Construction

Incorporating seismic considerations into the design and construction of buildings is much less expensive than attempting to retrofit an existing

structure. Furthermore, if new construction incorporates such features, eventually all buildings will

have them as older buildings are demolished. This

section reviews the state of the knowledge of designing new buildings to resist seismic forces. The

principal tool that determines the seismic performance of new buildings—building codes—is discussed, and several promising new technologies

are reviewed.

State of the Knowledge

Numerous technologies and practices for new

construction can reduce dramatically the risk of

structural failure. These range from relatively

simple design features, such as avoiding the use of

soft stories (i.e., large open spaces in the first

10 Risk Engineering, Inc., “Residential and Commercial Earthquake Losses in the U.S.,” report prepared for the National Committee on

Property Insurance, Boston MA, May 3, 1993, p. 2.
76 I Reducing Earthquake Losses

Unreinforced Masonry

Among the most dangerous buidings in an earthquake are those built of unreinforced masonry (URM).

These buildings are dangerous for two reasons 1) the floors and roof are often not strongly attached to the

walls and therefore the walls tend to collapse outward in an earthquake, and 2) the walls are often not strong

enough to absorb the shear forces experienced in an earthquake (masonry is very weak in tension, meaning

it has little resistance to being pulled apart). A relatively mild earthquake can turn a URM building into a pile of

rubble quite easily. URM is also one of the least expensive building techniques—leading to the unfortunate

outcome that lower income groups are often hardest hit by earthquakes. URM buildings are dangerous both

to occupants and to those nearby, who can be hit by falling masonry. For example, eight people were killed by

falling bricks in the Loma Prieta earthquake, all were killed outside a URM building.1

Concrete and Reinforced Masonry

A second type of building—made with reinforced masonry (in which steel reinforcing bars are used for

strengthening), concrete frames, or precast concrete—can be dangerous as well, although less so than

those built from URM. Concrete frame buildings—typically built in the 1950s to 1970s—are often large,

multistory commercial or office buildings. Even when these buildings have walls to absorb some of the

stress of an earthquake (called shear walls), the frame itself can fail. Precast concrete is often used for

single-story warehouse, light industrial, or commercial buildings. The concrete panels can simply fall away

from the building in an earthquake, due to inadequate connections between roof, floors, and walls,

Wood

Wood is often used as a structural material in single-family residences. It is the preferred construction

material for smaller buildings in high earthquake risk areas because, unlike concrete, it is flexible and can

bend without breaking. In an earthquake, a wood frame building will typically sway and bend, but will not

fail. It is rare for a wood frame building to suffer structural collapse in an earthquake. However, wood residences can be damaged, sometimes severely, by an earthquake. Unanchored wood houses sitting on concrete foundations can be knocked off their foundations, Short walls (called cripple walls) that provide support between the floor and the ground can tip, moving the house off the foundation and severing gas Iines

and utility wires. These dangers can be reduced at reasonable cost by, for example, bolting houses to

foundations and bracing cripple walls.

1 California Seismic Safety Commission, The Commercial Property Owner's Guide to EQ Safety, SSC 93-01 (Sacramento, CA

January 1993), p, 8,

floor) in apartment buildings, to the use of com- design and construct buildings that are unlikeplex computer models to assist in the design and ly to collapse in an earthquake. Years of relocation of structural members in a large office search have yielded a knowledge base that, if

building. Although considerable uncertainties ex- applied properly, would result in buildings that

ist in building performance under seismic stress, 11 are unlikely to collapse in an earthquake. Howit is generally agreed that the knowledge exists to ever such knowledge may not always be applied

 11 Examples include the steel weld issue (see box 3-1), and recent modeling suggesting that large buildings maybe vulnerable to collapse

from large ground motions. T. Heaton et al., “Response of a High-Rise and Base-Isolated Buildings to a Hypothetical Mw 7.0 Blind Thrust

Earthquake,” Science, vol. 267, Jan. 13, 1995, pp. 206-211.
Chapter 3 The Built Environment 177

Steel

Steel has long been considered the ideal material for large buildings in high earthquake risk areas. It is

extremely strong, durable, flexible, and ductile (i.e., it will bend slowly, rather than snap, if overstressed). A

steel-framed building is very unlikely to fail structurally from ground shaking in an earthquake. However,

faith in steel as a structurally sound material was shaken by the 1994 Northridge earthquake. In this quake,

more than 100 steel-framed buildings—including some under construction—exhibited a severe and costly

vulnerability not seen before: the steel beams themselves cracked at or near where they were welded to

steel columns. Although none of these buildings collapsed, repair will be very expensive. Furthermore,

these buildings were built to modern design standards. Presumably if they are rebuilt to these standards

they will be susceptible to the same damage if they are subjected to the same shaking forces. This unexpected vulnerability has international Implications because large buildings all over the world are similarly

built, and are presumably just as vulnerable to this type of damage.

What has become known as the steel-weld problem refers, in most cases, to cracks in steel supporting

members at or near welds that joined horizontal beams and vertical columns. In tall buildings, these beams

and columns are the backbone of the building. The discovery of cracks in these members usually leads to

immediate evacuation due to fear of structural collapse. This problem was discovered in a few buildings in

routine post-earthquake inspections; as awareness of the problem spread, cracks were found in more than

100 buildings. Since these cracks were in most cases found only by tearing down walls or other covering

material, many were not discovered until inspectors went looking for them.

There is as yet little agreement on why these failures occurred. Fears of financial liability have made all

parties sensitive to placing or accepting responsibility. Among the possible reasons raised are poor welding quality, poor steel quality, improperly designed connections, and inherent limitations of the beam-column design.

The first proposed technical fix was to reinforce the welds; however, tests of these reinforced welds

showed that they too would fail in a major earthquake.2 A second reinforcing method appears to perform

better in preliminary testing, but costs three times as much as a standard connection.3 Efforts to find effective and affordable solutions are continuing.

2 “Weld Test Failures Shock L.A,,” Engineering News-Record, June 13, 1994, p 9.

3 “Test Results Kick Off More Debate on Steel, ” Engineering News-Record, Sept 19, 1994, p. 8

properly because of lack of training, costs, and and well-constructed buildings performed well.”12

other reasons (these issues are discussed in chap- In the 1994 Northridge earthquake, damage was

ter 4). most severe in older and poorly engineered buildThere are numerous examples of the ability to ings. 13 The 1995 earthquake in Kobe, Japan,14

build structures that can resist seismic collapse. In also suggests that current designs can yield buildthe 1989 Loma Prieta earthquake, “well-designed

12 National Research Council, Practical Lessons from the Loma Prieta Earthquake (Washington DC: National Academy Press, 1994), p. 70.

13 

J.D. GOltZ (ed.), National Center for Earthquake Engineering Research, “The Northridge, California Earthquake of January 17, 1994:

General Reconnaissance Report,” Technical Report NCEER-94-0005, Mar. 11, 1994, p. 3-19.

14 This earthquake is sometimes called the Hyogo-Ken Nanbu earthquake to denote the three regions involved.
78 | Reducing Earthquake Losses

ings unlikely to collapse. Although the earthquake

caused massive losses and more than 5,000

deaths, new structures reflecting current building

codes performed quite well.15

Our knowledge and implementation of

technologies and practices to reduce nonstructural and contents damage is poor. Very little research has been done in these areas, and building

codes are for the most part directed at protecting

life safety by avoiding structural damage.16 An

analysis of residential insurance claims from recent California earthquakes found little correlation between the age of a building and the claim

amount: newer buildings, although much less

likely to collapse, were just as vulnerable to nonstructural damage.17

Building Codes

The knowledge of how to construct new buildings

to avoid structural failure is laid out in building

codes—detailed documents that summarize consensus design principles. Building codes are the

most important policy lever for incorporating

seismic considerations into new buildings; some

of their key features and constraints are summarized here. A detailed discussion of building codes

may be found in chapter 4.

In the United States, the local political jurisdiction typically regulates the design and construction of new buildings through the use of building

codes. These codes are intended to ensure the

health and safety of occupants. The codes typically set requirements for structural soundness, fire

safety, electrical safety, and in some areas, seismic

resistance as well. Most local building codes are

based on model codes. The three national model

codes are: the Uniform Building Code, which has

been adopted in part by much of the western

United States; the Building Officials and Code

Administrators code, generally used in the northeast United States; and the Southern Building

Code Congress International, adopted in the

southeastern United States. The seismic provisions of these three model codes are based in part

on what is known as the NEHRP (National Earthquake Hazards Reduction Program) Provisions.18

These NEHRP Provisions are produced by an independent organization (the Building Seismic

Safety Council) with NEHRP funding.

Codes have strengths and weaknesses that

should be recognized. First, building codes are

consensus documents. They are the results of negotiation and discussion among interested parties,

and they reflect a balance of safety, first-cost, performance uncertainty, and other concerns. Second, codes are intended to provide a minimum,

not an optimal, performance level. Although

codes are unfortunately often taken as prescriptive, they are intended to define a minimum acceptable level of safety. Third, codes are

technologically conservative. The process for updating and modifying codes is complex and time

consuming. The result is that new technologies

and practices can take years to make it into the

model codes. From there, many more years are

often necessary before a new model code is

adopted by localities. Fourth, codes are intended

primarily to prevent structural collapse. They

have few requirements for nonstructural damage

15 See, e.g., National Science Foundation, “Modern Buildings Fared Well in Kobe Quake, According to Preliminary Report,” press release,

Feb. 23, 1995; and “Kobe High-Rise Rebuilding on Hold,” Engineering News-Record, Feb. 20, 1995, p. 12. This second reference reports on a

post-earthquake survey in Kobe that found more than one-third of pre-1971 buildings were unsafe, while only 6 percent of buildings meeting

current codes were unsafe.

16 “The primary intent (of the Uniform Building Code seismic provisions) is to protect the life safety of building occupants and the general

public.” Earthquake Engineering Research Institute, Expected Seismic Performance of Buildings (Oakland, CA: February 1994), p. 6.

17 Confidential insurance industry data.

18 “Two Model Codes Stiffen Protection,” Engineering News-Record, Jan. 6, 1992, p. 7.
Chapter 3 The Built Environment I ’79

Estimated change in

Number of construction costs

Building type cases (percent)

Low-rise residential 9 0.7

High-rise residential 1 2 3.3

Office 2 1 1.3

Industrial 7 0.5

Commercial 3 1.7

Average — 1.6

SOURCE: S Weber, National Institute of Standards and Technology, “Cost Impact of the NEHRP Recommended Provisions on the Design and Construction of Buildings, ” 1985, p. 1-11,

or for protecting contents. Finally, they generally

apply only to new construction.19

Costs of Incorporating Seismic Provisions

in New Construction

The cost of incorporating seismically resistant

features into new buildings is frequently raised as

a barrier to greater use of these features, especially

in lower risk areas. These costs are heavily dependent on the design, location, and features of the

building, as well as the local costs of labor and materials. Several studies have tried to estimate these

costs through the use of representative case study

buildings. These studies found that incorporating seismic resistance features into new buildings increases construction costs by about 1 to 2

percent.

One study by the National Institute of Standards and Technology estimated the costs of complying with the NEHRP Provisions, relative to

building to the existing code. The study found an

average increase in construction costs of 1.6 percent (see table 3-5).20 A separate study estimated

these costs for new single-family residential

buildings. This study found that the costs of complying with the NEHRP Provisions, relative to existing practice, varied from O (some houses did not

need any changes) to 1.6 percent of construction

costs. 21 As in the previous study, these costs

would be higher as a percentage of structural costs

and lower as a percentage of total costs.

New Technologies

The traditional method of designing a building to

resist seismic damage is by strengthening the

structure. Although this is often effective at reducing the chances of structural collapse, significant

nonstructural and contents damage can still resuit.22 Furthermore, it is difficult and expensive to

retrofit existing buildings to make them suffi19 It is possible, however, to have building codes apply when existing buildings are extensively modified or expanded.

20 S. Weber, National Institute of Standards and Technology, “Cost Impact of the NEHRP Recommended Provisions on the Design and

Construction of Buildings,” 1985, p. 1-11. The choice of denominator in such an estimate is crucial. Construction costs include structural, material, labor, and all other costs associated with actual construction. They do not include land, site development, and other nonconstruction costs.

Costs as a percentage of structural costs would be three to four times higher; as a percentage of total costs they would be roughly half of those

shown in table 3-5.

21 NAHB Research Center, “Estimated Cost of Compliance with 1991 Building Code Seismic Requirements,” prepared for the Insurance

Research Council, Oak Brook IL, August 1992, p. 3.

22 The contents of 

a building are typically worth about half as much as the building itself. Risk Engineering, Inc., see footnote 10, P. 2.
80 | Reducing Earthquake Losses

A base isolator cut in half to show its construction.

ciently strong to withstand a major earthquake.

Two new technologies that may be able to reduce

damages in both new and existing buildings—

base isolation and active control systems—are reviewed here, promising information technologies

are discussed in box 3-2.

Base isolation

Rather than the usual method of stiffening a building to resist seismic damage, base isolation in effect disconnects the building from the ground.

This allows the ground to move underneath the

building while the building stays relatively still. If

successful, base isolation can protect both the

building and its contents. There are two principal

techniques for base isolation:

1. Installing rubber or rubber and steel pads,

called elastomeric bearings, between the building and the ground: when the ground moves in

an earthquake, the bushing bends and gives; the

building, however, stays relatively still.

2. Using a bearing and a concave surface: the

building’s columns are attached to a bearing or

other low-friction material, which in turn sits in

a concave surface. In an earthquake, the concave surface (which is attached to the ground)

slides around while the building stays still.

There are currently at least 30 base-isolated

buildings in the United States, and more than 65 in

Japan. 23 Applications of base isolation include

new buildings such as the Foothill Communities

Law and Justice Center in southern California,

opened in 1986, which uses 98 rubber bearings;

retrofits to existing buildings such as the U.S.

Court of Appeals in San Francisco, originally

built in 1905; and other structures such as a water

tower in Seattle and art objects in the J.P. Getty

Museum in Malibu, California.

Key questions of base isolation are:

● How well does it protect buildings and their

contents?

● How does its cost compare to conventional

techniques?

Computer modeling and laboratory testing of

base isolation suggest that it works quite well.

Laboratory tests of a base isolation system built to

protect a large statue indicate that the system reduces accelerations 35 to 45 percent at the top of

the statue.24 Computer modeling of a base isolation retrofit to a historic brick tower in Seattle predicted a 75 percent reduction in base shear.25 A

much better test of base isolation would be its performance during a real earthquake. Although no

base-isolated structures in the United States have

yet experienced a large earthquake, several have

been exposed to moderate ground shaking in recent years. Although data are still sparse, it ap23 D. Trummer and S. Sommer, Lawrence Livermore National Laboratory, “Overview of Seismic Base Isolation Systems, Applications, and

Performance During Earthquakes,” UCRL-JC-1 15114, August 1993, p. 2.

24 W. Haak, “Base Isolation System for Large Scale Sculptural Works of Art,” in Proceedings of the Fifth U.S. National Conference on

Earthquake Engineering, July 10-14, 1994, Chicago IL, vol. 1 (Oakland, CA: Earthquake Engineering Research Institute), p. 590.

25 D. Bleiman et al., “Seismic Retrofit of a Historic Brick Landmark using Base Isolation,” in Proceedings of the Fifth U.S. National conference on Earthquake Engineering, see ibid., p. 616.
Chapter 3 The Built Environment 181

Additional tools in the mitigation of seismic risks are post-earthquake notification and early warning systems (EWS). Notification systems use automated analysis of seismic data to estimate earthquake location,

magnitude, and the geographic distribution of potentially damaging ground motion within minutes of a

quake’s occurrence. Because electronic signals travel faster than seismic waves through the earth, EWS

can warn of approaching ground motion. Initial applications of future EWS include automated shut off of

valves and opening of firehouse doors; these actions impose low to moderate costs if the warning is a false

alarm. Should 30 to 60 seconds of warning be available, more applications are possible, including turning

off computers or halting manufacturing processes and initiating personal safety precautions in schools,

homes, or offices.

Development of Earthquake Notification Systems and EWS in California

In 1988, the California Division of Mines and Geology (CDMG) studied earthquake warning systems

and their potential benefits and costs in California. The agency concluded that, with existing technologies

and knowledge of earthquake hazards, construction of an EWS in California would not be justifiable on a

cost-benefit basis. 1

Within three years of this report’s release, however, the California Institute of Technology (Caltech) and

the U.S. Geological Survey (USGS), Pasadena—with the participation of local governments and the private

sector—began providing automated broadcasts of southern California earthquake magnitude and location

in near real time. Today, the Caltech-USGS Broadcast of Earthquakes (CUBE) system disseminates this

Information to the scientific community, public officials, electric utilities, and railroad operators via pagers,

electronic access to the Southern California Earthquake Data Center at Caltech, and direct phone Iines.

Another notification system, the Rapid Earthquake Data Integration (REDI) system, has been operating in

northern California since 1993. It uses data from University of California at Berkeley and USGS, Menlo

Park, seismographic stations located throughout northern and central California.

Factors contributing to the change of heart toward implementing EWS included:

■ The National Research Council issued a report that delineated the benefits of real-time analysis of seismological data.2

■ There were rapid advances in seismic data digitizers and sensors and satellite telecommunications capabilities.

1 See Richard Holden et al., Technical and Economic Feasibilityofan Earthquake Warning System in California, Special Publication 101 (Sacramento, CA, California Department of Conservation, Division of Mines and Geology, March 1989).

2 See National Research Council, Committee on Seismology, Real-Time Earthquake Monitoring: Ear/y Warning and Rapid Response (Washington, DC: National Academy Press, 1991)

(continued)

pears that base isolation systems reduced large ac- in an active seismic area. The building with base

celebrations yet had little effect on small accelera- isolators experienced, on average, about 75 pertions. 26 In one study in Japan, two identical cent lower acceleration than the conventional

buildings, one with base isolators and one with building during a series of moderate earthconventional technology, were built side by side quakes. 27 There is some evidence, however, that

26 Trummer and Sommer, see footnote 23, p. 3.

27 T. Kuroda et al., Argonne National Laboratory, “Comparison of Seismic Response of Ordinary and Base-Isolated Structures,” ANL/

CP—75357, 1992.
82 I Reducing Earthquake Losses

■

■

Increased attention was given to the earthquake threat, facilitated by the 1989 Loma Prieta earthquake

in the San Francisco Bay area and the 1992 Landers earthquakes in southern California.

There was improved perception by the private sector and local governments of the usefulness of

ground-motion information and early warning.3

REDI and CUBE coordinate to provide complete statewide coverage and to automatically notify the

state Office of Emergency Services, Department of Transportation, CDMG, utilities, telecommunications

providers, and transportation companies of significant events. Second, strong-motion estimates (for earthquakes of magnitude 5.5 or greater) are broadcast via the paging system and maps of strong-motion distribution are made available on the Internet. After initial source data and strong-motion estimates are released, the systems automatically calculate the seismic moment and moment tensor for the earthquake.

This helps to determine which fault planes are involved, to refine magnitude calculations, and to better

characterize rupture processes that determine the degree of severe shaking. 4

Future Directions

Besides developing EWS capabilities, goals for the existing notification systems include reducing analysis time and developing quick damage assessment capabilities to aid in emergency response and aftershock preparedness. For example, university and government researchers are working to include soil amplification and other site effects, and to integrate building inventories into the systems in order to rapidly

estimate zones of highest damage and casualties.

In a similar vein, work is under way to develop an automated rapid damage assessment capability intended to alleviate much of the uncertainty, delays, and inaccurate information associated with traditional

post-quake intelligence gathering.5 Data on the built environment are being collected and vulnerability assessment software is being developed that will accept CUBE and REDI data and predict both damage

areas and overall impact.

3 Egill Hauksson, Seismological Laboratory, California Institute of Technology, personal communication, June 28, 1995

4 Lind Gee, Selsmographic Station, University of California at Berkeley, personal communication, June 28, 1995

5 Ronald T Eguchi et al , “Real-Time Earthquake Hazard Assessment in California: The Early Post-Earthquake Damage Assessment Tool and the Caltech-USGS Broadcast of Earthquakes, ” paper presented at the Fifth U S National Conference on Earthquake

Engineering, July 10-14, 1994, Chicago, Illinois, p. 2.

base isolation systems as currently designed may new building. One cost analysis of a new building

be overwhelmed by large earthquakes that pro- in southern California found that base isolation

duce very large ground displacements.28 would be about 6 percent cheaper than convenThe costs of base isolation are not well known. tional design, with much of the savings coming

A commonly used estimate is that base isolation from eliminating the need for measures to protect

adds about 5 percent to the construction costs of a computers and other sensitive equipment.29

28 Heaton et al., see footnote 11.

29S. Sommer and D. Trummer, “Issues Concerning the Application of Seismic Base Isolation in the DOE,” in Proceedings of the Fifth U.S.

National Conference on Earthquake Engineering, see footnote 24, p. 603.
Chapter 3 The Built Environment | 83

Another study found the life-cycle costs of base

isolation to be comparable to conventional technology. 30

Although these studies suggest that the costs of

base isolation are competitive with conventional

design, costs are still uncertain. Most applications

to date of base isolation have been in buildings

where noncost attributes are crucial: experimental

buildings, historic retrofits where major interior

renovations were impossible, and buildings

where continuance of building function after an

earthquake was critical.

Active control systems

Another approach to minimizing earthquake damage is the use of active control systems, which detect earthquakes and respond to them. Although

many ideas for active control are still at the conceptual stage, some are beginning to be applied in

buildings. Perhaps the simplest example of active

control is the use of a large weight on the top of a

building; the weight is computer-controlled to

move so as to counteract the earthquake-induced

sway of a building. This technique, known as “active mass damping,“ is already used in some tall

buildings, including the John Hancock Building

in Boston, to reduce occupant discomfort from

wind-induced building sway.31 Such a system has

been installed in an office building in Japan to resist seismic damage.32

A more advanced approach is the use of “active

tendons’ ’-electronically controlled actuators

that can be instructed to shake the frame of a building so as to minimize earthquake-induced movement. These systems, although still far from

commercial application, have the potential to reduce both structural and contents damage by miniActive control systems being tested.

mizing building movement in an earthquake.

They could in theory be used in both new and retrofit applications. An active tendon system has

been installed in an experimental building in Tokyo, Japan.33

Issues affecting the development and use of

these systems include:

■ Cost. Most systems to date have been experimental and designed with little attention to

cost. The costs of commercial systems are as

yet unknown.

30 S. Pyle et al., “Life-Cycle Cost Study for the State of California Justice Building,” in Proceedings of Seminar on Seismic lsolation, Passive

Energy Dissipation, and Active Control, ATC 17- I (Redwood City, CA: Applied Technology Council, 1993), p. 58.

31 V. Vance, Langley Research Center, “Active Control of Buildings During Earthquakes,” NASA Technical Memorandum, December

1993, p. 3.

32“Structures Tuned to the Rhythm of a Quake,” New Scientist, Feb. 16, 1991, p. 33.

33 Vance, see footnote 31, p. 5.
84 | Reducing Earthquake Losses

Bracing parapets can reduce damage and injuries.

■

■

■

■

Reliability. These systems will be inactive most

of the time, but must work properly when

called on. Reliability is critical, and ensuring it

will increase cost.

External energy requirements. Active systems

require energy, and energy systems can be interrupted in an earthquake. If energy storage is

needed, costs will increase.

Potential for future applications. Since a welldesigned building is likely to avoid structural

damage in all but the largest earthquakes, the

value of active control systems will be largely

in their ability to reduce nonstructural and contents damage. This value has not been wellquantified.

Existing Buildings

Most buildings in existence today were

constructed before our current understanding of

how to build them to reduce seismic damage.

These older structures were built to earlier, less

stringent building codes. This section reviews

technologies and practices for reducing earthquake damage in existing buildings. It discusses

the costs of doing so and some associated policy

issues.

State of the Knowledge

Our understanding of how to retrofit existing

buildings to improve their seismic performance

has improved in recent years, due in part to

NEHRP-sponsored programs, yet numerous

knowledge gaps and uncertainties remain. Retrofitting is a more difficult task than new building

design for several reasons: the original plans of the

building may be missing or inaccurate; it maybe

necessary to allow the building to remain occupied while it is being retrofitted; owners may want

to preserve the appearance of a building (e.g., exterior seismic braces may be unacceptable); and,

as always, costs are a concern. Designing retrofit

methods that can overcome these obstacles is a

continuing challenge.

There are generally agreed-on principles that

can guide retrofitting. For example, typical steps

to reduce damage include bracing parapets; improving connections among walls, floors, and

roofs; strengthening the walls themselves; adding

structural framing to support exterior walls; and

modifying the building design to reduce asymmetry (symmetric buildings are generally stronger).

Work to refine these techniques is ongoing. Its

goal is to develop a set of comprehensive guidelines on seismic retrofitting of existing buildings. 34

Costs of Retrofit

The costs of retrofitting buildings to improve seismic resistance are uncertain, but are generally

much higher than incorporating seismic design

into new construction. The uncertainty is due to

several factors: seismic retrofits are often done in

conjunction with other building improvements,

such as appearance and fire safety, which makes it

34 The Federal Emergency Management Agency has published a number of related guidebooks and reports, and plans to complete retrofit

guidelines in 1997.
Chapter 3 The Built Environment | 85

difficult to separate the cost of seismic actions

alone;35 buildings and retrofit techniques differ

widely, leading to wide variations in costs; and

there is little agreement on the appropriate level of

retrofit (i.e., the level of safety a retrofitted building should provide).

Unreinforced masonry (URM) buildings have

received the most retrofit attention since they are

often the buildings at greatest risk for life safety.

Costs of URM retrofits are typically $7 to $18 per

square foot.36 To put these costs in perspective,

typical construction costs for new masonry buildings are $40 to $70 per square foot.37 Combining

these estimates yields a range of 10 to 45 percent,

with a midpoint of 23 percent: that is, retrofit of

URM buildings typically costs about 23 percent as much as new construction (although

costs will vary considerably). When this is

compared with the 1 to 2 percent additional cost of

incorporating seismic design into new construction (discussed above), it is clear that retrofitting

is much more expensive.38

Other Retrofit Issues

Few buildings in the United States have been retrofitted to improve seismic performance, even

though they represent a significant risk.39 Why are

retrofits so difficult to implement? Part of the answer is their high cost. As noted above, retrofits of

URM buildings typically cost about 23 percent as

much as new construction, and costs of retrofits

for other building types are comparably high. Perhaps more important, however, is that these retrofits offer little in the way of near-term market

benefits (which are typically a function of size,

location, amenities, and so forth). Not surprisingly, therefore, the retrofits that have occurred have

been largely in response to regulations requiring

them (chapter 4 discusses these issues in more detail).

A second issue complicating retrofits is determining the appropriate level of safety. Increased

safety comes at an increased cost. For new buildings, the minimum safety level is set by the building code. There is however no such generally

accepted code for existing buildings (although

guidelines are now available),40 and requiring

them to meet the same safety levels as new buildings would be extremely expensive.

A third issue is how well retrofits work. Data on

retrofit performance in earthquakes are rare; however, there is some evidence that retrofitted URMs

35 Performing a seismic retrofit may “trigger” other code requirements, such as fire safety upgrades.

36 Much of the variation can be explained by the level of seismicity to which the building is retrofitted and by the size of the building (larger

buildings have lower retrofit costs per square foot). Retrofit costs for non-URM buildings are in the same range—for example, retrofitting precast concrete tilt-up walls is estimated to cost $5 to $19 per square foot. Federal Emergency Management Agency, Typical Costs for Seismic

Rehabilitation of Existing Buildings, 2nd Ed., FEMA 156 (Washington, DC: December 1994), pp. 1-15 to 1-18.

37 OTA estimate, based on Federal Emergency Management Agency, Typical Costs for Seismic Rehabilitation of Existing Buildings, vol. 2,

FEMA 157 (Washington, DC: September 1988), p. 3-72.

38 Retrofitting, although more expensive than incorporating seismic considerations into new construction, can still be a worthwhile investment if the risk is high (e.g., in an area with a high probability of a damaging earthquake or in a critical building such as a hospital).

39 For example, a 1994 review of California’s seismic risk found, “we still have many earthquake-vulnerable buildings. . . .” California

Seismic Safety Commission, “California at Risk,” 1994 Status Report, SSC 94-01, p. 1. In the central United States, some states have just begun

to identify hazardous structures. R. Olshansky, “Earthquake Hazard Mitigation in the Central United States: A Progress Report,” in Proceedings

of the Fifth U.S. National Conference on Earthquake Engineering, see footnote 24, p. 992.

40 These guidelines, known as the Uniform Code for Building Conservation (UCBC), are intended not to ensure life safety but to decrease

seismic risk. For example, 15 to 25 percent of retrofitted URMs located near the epicenter of a major earthquake are expected to collapse in a

moderate earthquake. Earthquake Engineering Research Institute, see footnote 16, p. 16. In addition, as noted above, FEMA is working to develop comprehensive retrofit guidelines.
86 | Reducing Earthquake Losses

did not perform as well as hoped.41 Evaluation of

retrofit methods is clearly needed.

One major technical issue that makes such retrofits difficult is the analysis of existing buildings.

Deciding on a retrofit technique requires an understanding of the strengths and weaknesses of the

building as it stands. For many older buildings,

however, the original plans are not available; the

building has been modified several times since its

original construction; and structural details of the

building are hidden by nonstructural components.

Some work has been done by the National Institute of Standards and Technology (NIST) in applying nondestructive testing techniques, such as

sensors that can detect reinforcing rods in concrete, to seismic retrofit problems. The Federal

Emergency Management Agency (FEMA) has

also sponsored research into “rapid screening

methods”—methods to quickly estimate a building’s seismic hazard without performing a detailed engineering analysis. These are promising

research directions.

DAMAGE TO LIFELINES

Lifelines (i.e., bridges, mass transit systems, overpasses, roads, electric and gas supply systems,

water and sewer systems, and telecommunication

networks) are often damaged by earthquakes.

Much of what has been discussed about buildings

applies to lifelines as well:

 most fatalities associated with lifelines are

caused by structural collapse;

 the knowledge of how to build new lifeline facilities to minimize structural collapse is available, although this knowledge, for economic or

other reasons, may not be used;

 much of the remaining life safety risk lies with

existing facilities; and

 existing facilities can be retrofitted, but the

costs are high.

There are, however, some key ways in which

lifelines differ from buildings. The most important difference is the high cost of outage. If a

building is damaged, only the functions in that

building are lost. If a lifeline is interrupted—even

for a brief time—the costs can be massive. The

most extreme example would be loss of a water

supply system after an earthquake, which occurred in San Francisco in 1906, leading to massive fires. In the longer term, interruptions in

water or sewer service can lead to public health

problems, breaks in key transportation links can

snarl commuting, and the loss of natural gas systems can force otherwise undamaged businesses

to close. Thus “success” in lifeline seismic design

is often defined as retaining functionality rather

than simply reducing damage.

The second major difference is that lifelines

are usually owned and operated by public

agencies (exceptions are electricity and natural

gas supply systems, which in most areas are

owned and operated by publicly regulated, privately owned companies). Therefore, responsibility for their continued operation, and decisions

about their earthquake resistance, often lie entirely with the government.

❚ Bridges

Bridges, overpasses, and elevated highways are

often damaged by earthquakes, and the costs of

damage to these critical lifelines are high. Catastrophic failure can result in many deaths. Of the

63 deaths in the 1989 Loma Prieta earthquake, for

example, 42 were caused by the collapse of one

elevated highway.42 Repair of damaged bridges

can be very expensive: the reconstruction of the

41 For example, many retrofitted masonry structures suffered severe damage in the Northridge earthquake. Goltz, see footnote 13, p. 3-36.

42 M. Durkin, “Improving Earthquake Casualty and Loss Estimation,” paper presented at the Earthquake Engineering Tenth World Conference, Balkema, Rotterdam, 1992, p. 559.
Chapter 3 The Built Environment | 87

Santa Monica Freeway in Los Angeles, which was

damaged in the Northridge earthquake, cost $29.4

million.43 Also, interruption of transport services

can disrupt the local economy; the 1989 Loma

Prieta earthquake caused the partial collapse of the

San Francisco-Oakland Bay Bridge, which disrupted the passage of 243,000 vehicles per day.44

Bridges can be damaged in several ways, including:

 They can simply be “unseated.” Sections of

bridges typically sit on horizontal supports,

called seats; if the support moves far enough in

an earthquake it can simply drop the bridge section.

 The columns holding up sections of a bridge

may collapse under the lateral (side) forces

caused by an earthquake.

 The soil providing support for a bridge may

settle or shift.

Known technologies and practices can do much to

reduce the risk of major damage to or collapse of

bridges. The primary constraint is the high cost of

implementing these technologies and practices,

especially when such long-term investments must

compete with other public investments for scarce

capital.

New Construction

Like buildings, bridges built to current standards

of seismic resistance have performed quite well in

recent earthquakes. In the Loma Prieta earthquake, only one of the 100 bridges damaged was

designed after 1972, when seismic design requirements were revised significantly.45 Similarly, the

two major freeway collapses in the 1994 Northridge earthquake—the Santa Monica Freeway and

the I5-SR14 interchange—were due primarily to

the failure of supporting columns designed and

built before 1971.46 A total of seven highway

bridges collapsed in the 1994 Northridge earthquake; none were built to current codes.47 The elevated highway that collapsed during the 1995

quake in Kobe, Japan, did not incorporate current

knowledge on designing columns to resist seismic

damage.48

Some design features in new bridges that resist

seismic damage include: using continuous spans

and thereby eliminating joints that can separate

and collapse, using longer seat widths that allow

for more horizontal movement without unseating,

improving soil strength to avoid liquefaction, designing all bridge components for horizontal

loads, and confining (wrapping) columns.49

Retrofits

About 345,000 bridges in the United States were

built before 1970, with little or no consideration of

seismic resistance.50 Although not all of these are

located in areas of seismic concern, retrofitting

these bridges remains a major technical, financial,

and policy challenge.

Much of the bridge retrofit activity in the

United States has been in California. The 1971

San Fernando earthquake in southern California

43 “Quake-Damaged Freeway Reopening Ahead of Time,” New York Times, Apr. 12, 1994, p. A12. About half the cost was a bonus to the

contractor for early completion.

44 U.S. Geological Survey, “The Loma Prieta, California, Earthquake of October 17, 1989—Fire, Police, Transportation, and Hazardous

Materials,” 1553-C, 1994, p. C18.

45 National Research Council, see footnote 12, p. 169.

46 J. Cooper et al., “The Northridge Earthquake,” Public Roads, summer 1994, p. 32.

47 I.G. Buckle, National Center for Earthquake Engineering Research, “The Northridge, California Earthquake of January 17, 1994: Performance of Highway Bridges,” Technical Report NCEER-94-0008, Mar. 24, 1994, p. 1-1.

48 Earthquake Engineering Research Institute, The Hyogo-Ken Nanbu Earthquake, Preliminary Reconnaissance Report (Oakland, CA:

February 1995), p. 44.

49 Cooper et al., see footnote 46, p. 34.

50 Ibid.
88 | Reducing Earthquake Losses

damaged more than 60 bridges, and led both to revision of standards for new bridge construction

and to an ambitious bridge retrofit program. Retrofitted bridges performed very well in the 1989

Loma Prieta earthquake: 350 bridges retrofitted

with hinge restrainers were in the area impacted

by the quake, and none were damaged.51 Similarly, retrofitted bridges performed very well in the

1994 Northridge earthquake.52 Although some

hinge restrainers failed, no steel-jacketed column

retrofits showed signs of distress.53

The technical knowledge of how and what to

retrofit is good, but not faultless. The 1989 Loma

Prieta earthquake caused the partial collapse of the

San Francisco Bay Bridge; this bridge had been

retrofitted in the 1970s, and the section that collapsed was not considered vulnerable.54

In addition to determining the best technologies and practices for bridge retrofits, funding

these retrofits remains a major challenge. The

I-880 elevated highway that collapsed in the

Loma Prieta earthquake, killing 42 people, was

scheduled for retrofit but had not been because of

budget limitations.55 A General Accounting Office survey of state bridge retrofit activity found

that very few states had retrofitted their bridges;

limited funding was identified as a major barrier.56

❚ Water and Sewer Systems

Ground motion and ground failure due to earthquakes can cause water and sewer pipes to break;

this can be especially dangerous if fire follows an

earthquake. Also, since almost all of these pipes

are underground, repair is expensive and time consuming. The 1989 Loma Prieta earthquake caused

748 water supply pipeline breaks; the total cost of

repairs was in the tens of millions of dollars.57

This earthquake also severely damaged San Francisco’s auxiliary water supply system.58The 1987

Whittier Narrows earthquake caused 17 major water supply pipeline breaks, with the result that water pressure in the system was at half its usual level

for two days following the earthquake.59 The loss

of water supply contributed to the severity and

duration of fires in the 1995 Kobe, Japan, earthquake.

Recent experiences with the performance of

water systems in earthquakes suggest several design principles to reduce future disruptions. The

Loma Prieta and Northridge experiences point to

the importance of redundancies in water supply

systems. In the Loma Prieta earthquake, liquefaction in the South of Market area of San Francisco

caused a break in a major pipeline of the city’s

backup water supply system. Fortunately, other

backup systems, including cisterns and a fire boat,

were available. Water supply systems should

build in redundancies (e.g., multiple pipelines and

independent power supplies for pumping) to reduce the probability of the system’s being disabled from the loss of any one component. In the

Northridge earthquake, a number of water leaks

resulted from the breakage of pipes and valves

51 National Research Council, see footnote 12, p. 168.

52 Cooper et al., see footnote 46, p. 32.

53Buckle, see footnote 47, p. 1-1.

54 U.S. Congress, General Accounting Office, Loma Prieta Earthquake: Collapse of the Bay Bridge and the Cypress Viaduct, GAO/

RCED-90-177 (Washington, DC: June 1990), p. 5.

55 Ibid., p. 2.

56 U.S. Congress, General Accounting Office, The Nation’s Highway Bridges Remain at Risk from Earthquakes, GAO/RCED -92-59

(Washington, DC: January 1992), p. 13.

57National Research Council, see footnote 12, pp. 138, 146.

58 “Keeping Lifelines Alive,” Civil Engineering, March 1990, p. 59.

59 A. Schiff, “The Whittier Narrows, California Earthquake of October 1, 1987—Response of Lifelines and Their Effect on Emergency

Response,” Earthquake Spectra, vol. 4, No. 2, 1988, p. 344.
Chapter 3 The Built Environment | 89

where they connect to water tanks. Use of flexible

connections that would allow differential movement of pipes and tanks would reduce such leaks.

A $17-million evaluation and retrofit of Seattle’s

water supply system found that elevated water

tanks were among the most vulnerable components of the system.60 Ensuring that such tanks

have sufficient anchors and braces will reduce the

chances of collapse.

❚ Electricity Systems

In recent earthquakes in the United States, the

damage to electricity systems has been relatively

minor. Redundancies in transmission and distribution systems, coupled with the inherent flexibility of wires (i.e., compared to rigid pipes),

suggests that electricity is not the most vulnerable

lifeline. In the Loma Prieta earthquake, several

electrical switchyards were moderately damaged.61 In the Northridge earthquake, about 2 million customers lost electrical power due mainly to

substation problems; however, most service was

restored within a day.62

Fortunately most critical facilities that use electricity—such as hospitals, telecommunications

systems, and computer facilities—have backup

electricity-generating facilities. However, since

most backup systems such as batteries and on-site

generators are designed to supply limited power

for only a short time (typically hours or tens of

hours), longer term electricity system damage can

be a serious problem.

❚ Natural Gas Systems

Natural gas is transported through underground

pipelines, which are vulnerable to fracture in

earthquakes. Resulting natural gas leaks are a

dangerous fire and explosion hazard. In the Northridge earthquake, a broken natural gas transmission pipeline caused a fire that destroyed five

houses.63 Analysis of the performance of natural

gas transmission pipelines in California earthquakes found that most damage could be traced to

pre-1930 welds, which were generally of poor

quality. Pre-1930 pipes had a damage rate 100

times that of post-1930 pipes.64 Modern pipes

with high-quality welds are still vulnerable to

ground deformation, but are very resilient to damage from traveling ground waves.

Although modern natural gas transmission systems generally perform quite well in earthquakes,

leaks and other problems in the distribution system and at or near the service connection are common. In the 1987 Whittier Narrows earthquake,

for example, there was only one leak in the transmission system (due to a cracked cast iron pipe)

but there were 1,400 leaks on customer property.

Three-quarters of these resulted from failures at

appliance connections, primarily water heaters.65

In the Loma Prieta earthquake, the natural gas

transmission system was undamaged, but the distribution system suffered extensive damage. Repairs in many cases were made by inserting

flexible plastic piping into damaged cast iron

pipes.66 In the Northridge earthquake, 120 mobile

60 W. Anton et al., “Seattle Plays It Safe,” Civil Engineering, August 1992, p. 39.

61 National Research Council, see footnote 12, p. 142.

62 Goltz (ed.), see footnote 13, p. 4-11.

63 Ibid., p. 4-21.

64 T. O’Rourke and M. Palmer, National Center for Earthquake Engineering Research, “The Northridge, California Earthquake of January

7, 1994: Performance of Gas Transmission Pipelines,” Technical Report NCEER-94-0011, May 16, 1994, pp. 2-32, 2-35.

65 Schiff, see footnote 59, p. 348.

66 National Research Council, see footnote 12, p. 140-141.
90 | Reducing Earthquake Losses

homes were destroyed by fires triggered by natural gas valve leaks.67

ACCOMPLISHMENTS AND NEEDS OF

FEDERALLY SPONSORED RESEARCH

❚ Accomplishments

Considerable progress has been made in understanding how the built environment is affected by

earthquakes and how structures can be designed to

reduce structural failure. NEHRP has done

much to expand our knowledge of earthquake

engineering. Although a rigorous evaluation of

NEHRP has not been undertaken (and would be

very difficult, since much of NEHRP involves research, which is inherently difficult to evaluate),

there are numerous examples in which NEHRPfunded programs have had considerable societal

benefits.

A 1993 workshop defined some key contributions made to earthquake engineering by the National Science Foundation’s funding of research

under NEHRP. These include:

 advances in analytical and modeling techniques, permitting seismic structure design on

inexpensive computers;

 improved understanding of how structures behave under earthquake-induced stress, which

has led to better building codes in such areas as

bracing systems for steel structures;

 advances in new technologies such as base

isolation and active control;

 better reliability and risk assessment techniques for lifelines and structures; and

 improved disaster response planning from social science research that sheds light, for example, on cultural differences in perceptions of

disaster.68

NEHRP-funded work by NIST, although a

small fraction of total program funding, has also

addressed some key applied earthquake engineering problems. Examples include testing of base

isolation systems, development of methods to

evaluate the strength of existing buildings, and

evaluation of building retrofit techniques.69 Additional relevant NIST activities include, for example, development of seismic standards for existing

federal buildings and management of a United

States-Japan annual meeting on earthquake engineering.

Implementation of this knowledge is a continuing concern; yet there are successes here as well.

For example, development of the NEHRP Provisions, a resource document for model codes, and

their adoption by model code agencies, is a significant accomplishment. Retrofitting of existing

buildings is still a difficult and expensive task, yet

FEMA’s work in this area has made some progress

toward consensus on methods and costs.

These examples of NEHRP successes are not

the result of a thorough evaluation of that program, nor do past successes ensure future contributions. However, it is clear that NEHRP has

made a significant contribution to improving understanding of how to build structures that will resist seismic damage. (A more detailed description

of the current activities of NEHRP agencies can be

found in appendix B.)

❚ Future Needs

Knowledge of how to design and build structures

so as to reduce earthquake-induced damage has

improved considerably. However, the problem is

far from solved. The 1994 Northridge earthquake

occurred in probably the most well-prepared area

of the United States. Nevertheless, it caused 57

67 Goltz (ed.), see footnote 13, p. 6-5.

68 National Science Foundation, “Directions for Research in the Next Decade,” Report on a Workshop, June 1993.

69 Richard N. Wright, Director, Building and Fire Research Laboratory, National Institute of Standards and Technology, testimony at hearings before the Senate Committee on Commerce, Science, and Transportation, Subcommittee on Science, Technology and Space, May 17,

1994, on NEHRP reauthorization.
Chapter 3 The Built Environment | 91

deaths and about $20 billion in losses. Scenarios

of future earthquakes across the United States suggest that large losses are likely.

Greater use of existing knowledge, practices,

and technologies could reduce these losses. For

example, the 1989 collapse of the I-880 elevated

highway in Oakland, which resulted in 42 deaths,

could have been prevented with the use of known

technologies. The implementation (or lack thereof) of these technologies to date has been determined largely by economic, behavioral,

institutional, and other factors, not by the state of

the knowledge (these issues are addressed in chapter 4).

Nevertheless, improved knowledge could have

several benefits. First, although current knowledge of how to build new structures to resist seismic damage is good, it is far from perfect

(consider the steel weld failures in new buildings

in the Northridge earthquake). Second, many of

the financial losses in recent earthquakes resulted

from nonstructural and contents damage—areas

that have received little research attention. Third,

much of the risk of fatalities lies in existing structures, and retrofit methods are still not well developed. Research into improving retrofits could

reduce this risk. Fourth, to the extent that economic factors influence implementation, research to

reduce costs could lead to greater implementation.

New Buildings

Buildings constructed to comply with today’s

codes are meeting the goal of providing life safety.

Building collapses have been limited largely to

older buildings designed to earlier codes. This is a

major success, for which NEHRP gets some credit: years of research, and a concerted effort to ensure that the results of this research are

incorporated into codes, have resulted in effective

new building codes that, if properly applied, will

yield a building that is unlikely to suffer structural

collapse.

However, several crucial areas of new building

seismic design are still not well understood. A

new building meeting today’s code, although unlikely to suffer structural collapse, will likely suffer expensive nonstructural and contents damage

in a major earthquake. This does not indicate inadequate or faulty construction or design. Rather, it

reflects the fact that codes are intended primarily

to protect life safety by preventing structural collapse and typically have few or no requirements to

limit nonstructural or contents damage.70 It is

time for new building seismic engineering research to consider the next problem: reducing

nonstructural and contents damage. Possible

areas of research include:

 data collection and analysis of nonstructural

and contents damage from recent earthquakes;

 how to design and build structures to avoid or

minimize expensive nonstructural failures

such as cracked walls, broken sprinkler systems, and collapsed chimneys;

 analytical methods to measure or predict such

damage;

 guidelines for lighting, electrical, water, and

other systems design and installation to minimize seismic damage;

 expanding building codes to address nonstructural and contents damage; and

 considering technologies—notably active and

passive control—that can reduce these damages.

The major surprise of the 1994 Northridge

earthquake was the failure of steel welds. These

failures occurred in new buildings and in buildings under construction. Although none of these

buildings collapsed, repairing this damage will be

very expensive. Since it is not yet clear why such

damage occurred or how to prevent it, repairs may

70 “The primary intent [of the Uniform Building Code seismic provisions] is to protect the life safety of building occupants and the general

public.” Earthquake Engineering Research Institute, see footnote 16, p. 6.
92 | Reducing Earthquake Losses

Testing of URM retrofit methods

not prevent the recurrence of this problem. Researcg is needed to better understand what caused

this failure and how steel frames should be designed, assembled, and modified (in existing

buildings) to prevent it from happening again.71

Existing Buildings

Much of the risk of collapse and resulting fatalities lies in existing buildings, which do not incorporate current codes and knowledge. Few of these

buildings have been retrofitted to reduce risk, and

such retrofits have sometimes been expensive,

complex, and of uncertain benefit. Additional research is needed to improve understanding of how

to best reduce the risk in existing buildings. 72

The first area of research for existing buildings

should be to better understand the vulnerability of existing buildings. It is commonly recognized that URM buildings are unsafe. However,

for other types of buildings (e.g., precast concrete

framed buildings or reinforced masonry buildings), the risk is less well known. Laboratory and

field experiments, and collection and analysis of

data on how buildings respond during earthquakes, are needed. Improved tools to determine

risk in existing buildings—such as nondestructive

evaluation techniques—are needed as well. A second area is the development of low-cost standardized retrofit techniques. Many retrofits to

date have been expensive and have required extensive site-specific design and analysis. Standardized methods, such as those contained in codes for

new construction, would reduce costs. These

methods could also allow for multiple levels of

safety to accommodate different risk preferences.

A third research area is to extend retrofits from

structural damage reduction to nonstructural

and contents damage reduction. The bulk of

damage to buildings in recent California earthquakes has been nonstructural and contents damage; retrofit methods to reduce this damage could

be very beneficial.

Lifelines

Lifelines are expensive to repair if damaged in an

earthquake, and service interruptions are at best

inconvenient and at times deadly. Like buildings,

lifeline facilities built to current design knowledge generally behave quite well in earthquakes.

However, the lack of an accepted national standard for the design and construction of lifelines

raises costs and reduces performance. The 1990

NEHRP reauthorization directed FEMA and

NIST to work together to develop a plan for creating and adopting design and construction standards for lifelines. The legislation directed the

agencies to submit this plan to Congress by June

30, 1992. Although some work has been done on

the plan, as of this writing it had not yet been submitted to Congress.

Much of the life safety risk associated with lifelines lies in existing facilities. Research is needed

to develop methods to better determine the risk in

71 Fema is currently using supplemental appropriations funds, passed after the Northridge earthquake, to sponsor research and development related to the steel weld problem.

72 FEMA has an existing buildings program that is addressing some of the issues noted here.
Chapter 3 The Built Environment | 93

existing facilities, to develop methods to prioritize retrofits, and to develop standardized retrofit

methods that can reduce retrofit costs. A goal of

preserving functionality, rather than simply minimizing damage, is often appropriate for lifelines. The development of low-cost, easy-to-use

procedures to analyze lifelines for weak links

would help to ensure their continued function in

earthquakes. 
Implementation

rom earth science comes knowledge of earthquake hazards; from engineering, an understanding of how to prepare structures against them. For this knowledge and

understanding to actually reduce earthquake losses, however, it must be put into effect. This process, the transformation of

research results into real-world measures that will reduce loss of

life and property, is referred to as implementation.

Implementation can take a number of forms. It can mean the

incorporation of engineering lessons into the building practices of

a seismically vulnerable region, land-use planning to restrict development of unusually dangerous ground, emergency planning

to ensure service or business continuity in the aftermath of a major temblor, or informational outreach programs to inform potential earthquake victims of risks and preventive measures. It is a

complex, multifaceted process involving many different players

working at many different levels, and as such it is inherently challenging.

In many respects, implementation is the chief bottleneck hindering seismic mitigation efforts in the United States. Research in

the earth sciences and engineering has already provided much of

the knowledge base needed to prepare against earthquakes: we

have a good idea of where earthquakes can occur (at least for the

more seismically active areas); we have a sense of their potential

severity and probable effects; and where we choose to prepare, we

can significantly reduce the likelihood of massive destruction and

loss of life. The problem is that we do not always choose to prepare. Despite mounting evidence that truly devastating earthquakes can occur in heavily populated regions of the central

United States, Intermountain West, and U.S. East Coast, these regions remain highly vulnerable to future earthquake losses. | 95
96 | Reducing Earthquake Losses

Moreover, where we do choose to act (most notably in the state of California), we have focused on

issues of life safety and remain vulnerable to devastating economic loss.

These problems—a general lack of earthquake

mitigation in many seismically hazardous regions

(particularly outside California), and a surprising

economic vulnerability in even the best-prepared

communities—have drawn attention to how the

implementation of seismic mitigation might best

be improved.

The emphasis in the National Earthquake Hazards Reduction Program (NEHRP) has traditionally been on the front end of the implementation

process (i.e., the gathering and dissemination of

research knowledge and recommendations), with

the actual execution largely left to state and local

authorities, private organizations, and private individuals. As a result, implementation might be

improved through better coordination and tailoring of front end efforts to the needs of nonfederal

implementers. Alternatively, one might desire to

complement existing efforts by having the federal

government play a more active implementation

role through incentives, insurance, or regulation.

All such efforts require an understanding of how

the implementation process works, who the chief

players are, what their relations are to NEHRP and

to each other, and what incentives or disincentives

influence their desire or ability to act. Those seeking to improve mitigation efforts in the United

States must therefore consider the following:

 How does implementation work in the ideal

and in practice?

 What underlying factors reduce implementation success?

 What activities or measures have the greatest

impact on implementation success?

These questions are considered in turn. The

next section, “The Implementation Process,” examines the basic workings of implementation and

identifies difficulties that arise in the execution of

mitigation measures. Following that, “Factors Affecting Implementation” sets these difficulties in

the context of larger motivational problems that

complicate the widespread and thorough adoption

of mitigation programs. Finally, the section “How

Matters Might Be Improved” identifies earth science, engineering, and direct implementation

measures that might improve mitigation adoption

and execution.

THE IMPLEMENTATION PROCESS

❚ The Voluntary Nature of

Earthquake Mitigation

From the perspective of the federal government,

the implementation of earthquake mitigation

measures is an essentially voluntary process. Federally supported research gives warning of likely

earthquake hazards while suggesting possible

technical countermeasures, and concerned nonfederal entities decide whether to incorporate

those suggestions into state, local, or private hazard reduction schemes.

The origins of this approach lie partly in the unusual scientific climate surrounding NEHRP’s

conception (a point addressed later) and partly in

matters of constitutional authority. That is, although federal funds can guide the course of research, the application of research results takes

place primarily through land-use decisions and

building codes—authority over which is constitutionally ceded to the states—and through action

by individuals and nongovernmental organizations.

To explain in more detail, the essential goals of

mitigation are to ensure that buildings and other

structures do not collapse, that lifelines and services continue to function, that individuals and organizations are aware of risks and appropriate

responses, and (a more recent concern) that economic losses are minimized. The basic tools to accomplish these goals are:

1. building codes for new construction in seismically hazardous areas;

2. retrofit or demolition programs and guidelines

to reduce or remove the risk of potentially hazardous older construction;
Chapter 4 Implementation | 97

3. land-use planning or zoning measures to prevent development on particularly dangerous

ground (e.g., fault scarps and landslide zones),

or to limit such development to nonessential,

less vulnerable uses;

4. actions by individuals or nongovernmental

groups to reduce nonstructural hazards (e.g.,

anchoring office equipment), or to initiate measures (land-use, retrofit, seismic-safety standards) beyond those recommended by the

government;

5. structural, organizational, or emergency response measures to ensure lifeline survivability; and

6. the collection, processing, and dissemination

of information on earthquake risk, mitigation

alternatives, and earthquake response to at-risk

individuals and organizations.

Of these tools, the first three (which have the

greatest impact on reducing catastrophic building

collapse and major loss of life) are building and

land-use issues, while the fourth is, by definition,

private. The federal government has some influence on lifeline survivability via authority over

utilities and transportation (and of course on direct

federal construction), but its basic role in implementation is currently focused on the last measure—collecting, processing, and disseminating

information.1 This handling of information serves

two functions: one is to motivate nonfederal entities toward action by making clear both the risks

and the potential losses; the other is to facilitate

action by translating research results into readily

usable forms (e.g., by incorporating engineering

theories into ready-to-use model building codes).

❚ Approaches to Implementation

With federal agencies currently playing a primarily informational role, authorities in the state, local, and private sectors are faced with devising

their own plans for putting hazard reduction into

effect. Because different parts of the country vary

in their geology, hazard awareness, economics,

political climate, and mitigation history, these

plans show a wide range of approaches:

 The overall approach can be regulatory, incentive- or insurance-based, or built on outreach

and the media.

 Action can be initiated by states, localities, professional and technical associations, or the private sector.

 In some instances (e.g., hospitals and schools

in California), the state takes a direct role in

mandating preventive measures. Alternatively,

the state can issue voluntary guidelines for local jurisdictions, or it can set performance standards that local authorities must attain.

 Considerable discretion is commonly left to local governments. Where state activity is weak,

local authorities sometimes take the lead (indeed, localities in even the most active states

are free to adopt more stringent measures than

required).

 Finally, important mitigation decisions can be

made at a nongovernmental level by regional or

local utilities, private businesses, professional

societies such as those guiding the training and

practice of engineers, organizations governing

particularly sensitive institutions such as museums and laboratories, and private individuals.

Despite the variety of mitigation approaches,

some common themes recur. In deciding whether

and how to guard against earthquake hazards,

communities, organizations, and individuals will

generally seek to:

1. assess the local level of seismic hazard and local vulnerability to that hazard,

2. decide what changes should be made to the existing and future built environment while ensuring that the benefits of such changes

outweigh the costs, and

1The federal role could be larger, and options for making it so are presented in chapter 1. However, this discussion reflects the federal role as

it currently exists.
98 I Reducing Earthquake Losses

Most severe

A community’s first step in assessing earthquake risk is to consult large-scale seismic hazard maps; here, the severity of future

ground shaking is shown for the continental U.S.

3. devise regulatory, financial, insurance-based,

or cooperative tools to put those changes into

effect.

Although simple in concept, these steps—particularly the first-are not straightforward to

execute. To illustrate the difficulties that arise, the

remainder of this section examines how a hypothetical (and unusually thorough) community

might approach each of the above steps. For clarity’s sake, each step is presented in sequence, with

the assumption that conscious, rational thought

governs every phase of the process. In the real

world, communities or individuals will likely deal

with steps simultaneously or in varying sequences, perhaps making decisions on the basis of

less-than-formal deliberations; however, the basic

problems that arise are the same whether the decisionmaking process is explicit or implicit.

■ Assessing Hazard, Risk, and Vulnerability

Assessing Overall Hazard—Seismic

Hazard Maps

As a first step, this hypothetical community will

examine U.S. Geological Survey (USGS) seismic

hazard maps2 to gain a sense of the overall danger.

Of concern are:

■ the frequency of seismic activity and the likelihood of activity within a future time window,

■ the most likely severity of future events, and

■ the severity of the worst-case event.

All three points are subject to considerable uncertainty, and all have an impact on the scope and

character of the desired mitigation action.

The first point reflects the immediacy of the

earthquake threat and can determine the choice of

implementation tools. If a community can reason2 There are many types of seismic hazard maps. See chapter 2 for more details.
Chapter 4 Implementation | 99

ably expect a damaging quake several hundred

years from now3—by which time most or all of its

current building stock will have already been replaced—then seismic codes for new construction

might suffice for future protection. However, if a

major seismic event is expected within the next

few years or decades (i.e., within the lifetime of

many existing buildings), prudence may dictate

more drastic measures such as building retrofit or

demolition and replacement. The difficulty is that

situations are rarely so straightforward. Because

earthquake likelihood is commonly expressed as a

probabilistic estimate (i.e., there is a percentage

chance of an event during some future time interval) and because building lifetimes vary widely,

communities must judge the impact of an uncertain future event on an evolving building stock. As

a result, communities must balance the risk of

overmitigation (e.g., by tearing down or retrofitting structures that would never have experienced

an earthquake) against that of mitigating too slowly and being caught unprepared.

Apart from issues of urgency is the question of

earthquake severity: should one prepare for the

worst-case scenario, or for the most-likely? The

geologic stresses that lead to seismic activity (see

chapter 2) can be released by earthquakes of many

different sizes, and those preparing for them must

choose from a range of predicted calamities. This

choice creates problems for those trying to justify

the expense of mitigation, for over- and underpreparation can both waste money: overpreparation

is expensive for obvious reasons, while an expensively but inadequately prepared building can still

be destroyed at a a total loss.

Assessing Risk in Detail

It is tempting to stop the assessment process at the

level of the seismic hazard map—knowing the

predicted zone of devastation surrounding future

earthquakes, one could in theory simply require

that all structures within the zone be built to

seismically resistant standards.

Real-world costs however make a broad-brush

approach impracticable on two counts:

1. In many regions (particularly east of the Rockies) scientific uncertainties mean that enormous portions of the seismic map are marked as

potentially hazardous. A broad-brush mitigation strategy can therefore prepare a widespread area for a future earthquake that, if and

when it occurs, might strike but a small fraction

of the region.4

2. Even if predicted earthquake locations are

tightly constrained, a broad-mitigation strategy

can still be undesirable. Within the general area

affected by an earthquake, quirks of local geography and geology will make some localities

much more dangerous than others (see chapter

2); these quirks are largely ignored in the preparation of seismic maps. Applying an average

level of mitigation to the entire area will thus

tend to overprepare some localities while underpreparing others.

For practical and economic reasons, a community will therefore wish to focus its efforts on locations where devastation is most likely. Places

subject to ground failure, seismic energy amplification, and other earthquake-related effects (see

chapter 2) can experience the bulk of a region’s

earthquake damage and will call for special attention (or sole attention, if the commitment to mitigation is weak). Because the typical seismic

3 Such an expectation can never be certain, for there is a certain probability that an earthquake can occur at any time; however, a community

in a seismically inactive region may judge its near-term earthquake risk to be too low to warrant drastic action.

4 This form of overpreparation is particularly troublesome where earthquakes are infrequent, in which case many of the region’s buildings

will never experience an earthquake during their lifespans.
100 | Reducing Earthquake Losses

Earthquake-reduced ground failure (liquefaction) can

endanger even the most well-constructed buildings

(Niigata, Japan, 1964).

hazard map predicts only the average severity of

ground shaking that would occur on an average

piece of land, the community will likely have to

conduct its own study of local geologic conditions. This sort of “microzonation” assessment is

typically far beyond the technical capability of a

local government, and although some metropolitan regions have been studied through state efforts

or because of special interest on the part of earth

scientists, a community will generally have to hire

a geotechnical firm to perform the work.

Assessing Vulnerability: Inventory

and Damage Estimation

Although one might expect the damage pattern in

a community to coincide with the pattern of maximum ground shaking (subject to the microzonation effects noted above), the damage a given

building experiences in an earthquake will depend

on its design, the type and quality of its construction, and how the building reacts to the particular

ground motion characteristics of the earthquake

(see chapter 3). Hence, it is not enough to know

the local geology and geophysics-one must also

estimate how the building stock will respond.

Such an estimate requires an accurate inventory of

the local building stock and predictive tools relating earthquake damage to building type.

Unfortunately, most communities do not possess workable building inventories. Inventories

may simply not exist, they may be outdated, or

they may be expressed in terms that are of little use

for mitigation (e.g., an inventory developed for

tax or urban planning purposes might classify

buildings according to function while including

nothing about their construction).

A concerned community will therefore probably conduct a building survey to learn what

buildings it has, what condition they are in, and

where vulnerable structures are located. Again,

this is not a straightforward task, particularly

when it comes to the most worrisome older structures. That is, it is generally not enough to simply

walk down a street and note down what buildings

stand along it: a given “old building” might be

made of unreinforced masonry; reinforced masonry; or some hybrid, much modified arrangement of wood, stone, metal, or concrete.

Therefore, a judgment on its construction and vulnerability may require physical inspection by a

specialist. 5

Finally, having determined its building inventory, the community must relate that inventory to

what it knows of the earthquake hazard and come

up with an estimate for likely future losses. Ideally, this estimate will include economic loss and

casualty figures broken down by building type

and geography. Again, such an estimate is not

straightforward, because the relation between

earthquake damage and building design or

construction is as yet poorly understood. However, if it can be done, such an estimate will allow

a community to target those areas in which it is

most vulnerable, and expend less of its resources

in areas that are more robust.

Earthquake loss estimates thus function as a

mitigation tool of singular importance. By reducing mitigation costs while increasing the likely

5 The technical expertise requied for such an inventory suggests a possible avenue for federal implementation assistance.
Chapter 4 Implementation 101

 . High Potential

NOTE: This Information IS for general planning

purposes only. It IS not intended to be used for

site specific data.

SOURCE: U.S. Geographical Survey

Earthquakes Hazard Reduction Program.

UTAH State University. 1985

3300 South

3900 South

Department,

4500 South

4800 South

Detailed risk assessment requires the preparation of small-scale seismic zonation maps,

in which local geologic dangers are

matched to features of the built environment. Here, the potential for liquefaction in a Utah community iS over/am on a map 01 city

streets.

benefits, a quantitative loss estimate can increase

the effectiveness of current mitigation efforts

while making it much more likely for as yet undecided communities to act. Unfortunately, although work is progressing on this front, reliable,

consistent estimates are extremely difficult to obtain. 6

The Office of Technology Assessment (OTA)

notes an exceptional lack of quantitative information on expected earthquake losses in specific urban areas of the United States. Loss estimates

have been made for certain regions (most notably,

metropolitan areas in California), but variations in

methodology, scope, assumptions, and even terminology make interpreting or comparing their

results difficult. Further lacking are comprehensive data showing the change in expected losses

that would result from mitigation--data essential

to judging the cost-effectiveness of different mitigation measures. Indeed, many at-risk communities (particularly smaller urban centers in areas

outside of California) have little more than a sense

6 The Federal Emergency Management Agency, under NEHRP, is sponsoring the development of a computer-based loss estimation tool that

could allow communities to estimate risk and prioritize risk reduction efforts.
102 Reducing Earthquake Losses

Land-use planning measures are best employed where local geologic conditions create unusually severe hazards (e.g.,

clockwise from upper left: fault scarps; Iandfills and land reclaimed from the sea; outwash and alluvial fans; unstable slopes).

that some sort of disaster might happen sometime

in the future, and that some sort of preventive action should be taken. Missing are hard data on

what are the expected losses, and in what functional and geographic areas will they occur. Without such data, communities can only guess how to

respond.

❚ Modifying the Built Environment

Having assessed the risk as well as it can, a community has a choice of mitigation tools with

which to proceed. Possibilities include:

■ land-use planning and zoning,

■ building codes for new construction,

■ retrofit or demolition of older construction, and

■ systems-related, small-scale, and private activity (including emergency planning).

Although each of these has an impact on both life

safety and economic loss, the first three tend to affect life safety issues, while the fourth is more directed toward economic damage.

Land-Use Planning and Zoning

The simplest and most drastic mitigation option is

to avoid building things where earthquake hazards

are expected. However, such an option is also the

least used, and in practice land-use planning generally entails not the outright banning of development, but the tailoring of land use to forms less

susceptible to earthquake damage.

Abolishing development on hazardous ground

is most acceptable when the risk is clear, the alternatives are poor, and the geographical extent of

the expected damage is limited. For earthquakes,

circumstances meeting these criteria are relatively

rare. The presence of a historically active surface

fault rupture offers a possible candidate, in that the

likelihood of future fault movement is evident, the

engineering options are nonexistent (few structures can resist being torn in two, regardless of

their construction), and the most damaging geologic effects occur in a tightly constrained area immediately adjacent to the fault.
Chapter 4 Implementation | 103

However, even where conditions seem right,

strict land-use measures such as development

bans rarely appear as a mitigation tool. The history

of earthquake disasters shows no end of instances

where major structures have been built along

known faults, even in seismically aware California (e.g., the stadium of the University of California at Berkeley sits atop the Hayward Fault), and

with relatively rare exceptions (e.g., the “Faultline

Park” in Salt Lake City), such measures are generally unpopular.

The roots of this unpopularity lie in the geographic nature of the earthquake phenomenon.

Unlike floods, which typically strike clearly defined parts of floodplains and coasts, the primary

earthquake hazard—ground shaking---can be distributed over an area so broad that general development bans become impractical (clearly one

cannot halt construction in all of Los Angeles).

Even local bans in places of obvious fault rupture

or ground failure are often thwarted by a variety of

socioeconomic objections (e.g., earthquake faults

possess a perverse ability to create potentially

valuable real estate with spectacular views).

Moreover, typical seismic recurrence intervals of

a lifetime or longer mean that bans must be maintained through years or decades of seismic inactivity.

The more likely use of land-use planning is

thus in a milder form in which development on

dangerous land, though permitted, is restricted to

its less vulnerable forms. Thus, for example, a

community might identify an undeveloped parcel

of land that is subject to liquefaction or landslide,

and limit construction to single-story, low-occupancy dwellings, or perhaps to noncritical industrial uses such as warehousing (such is one effect

of California’s Alquist-Priolo Act, see box 4-1 ). In

this way, land-use planning is used not to prevent

earthquake damage outright, but to reduce its direct and indirect impacts. Alternatively, a community might designate high-risk areas as sites

Areas of extreme earthquake hazard-such as this fault scarp

in Utah—are often attractive locations for development.

requiring special geologic and engineering consideration before building can proceed (as in

Utah’s Salt Lake County Natural Hazards Ordinance, see box 4-2), thereby ensuring that vulnerably sited structures are more seismically resistant

than the norm.

Building Codes for New Construction

With land-use planning reserved for special cases,

a concerned community will commonly turn to

the most broad-based of mitigation tools—the incorporation of seismic provisions in building

codes. By using codes to effect seismically resistant construction, a community can replace the

bulk of its building stock over time with one less

vulnerable to damage and collapse. Because the

approach does not restrict or modify land-use patterns, and because it is relatively inexpensive

when applied strictly to new construction (see

chapter 3), it can be more politically palatable than

a broad-based land-use planning approach.7 For

all these reasons, building codes are perhaps the

most popular of implementation options, and are

often (erroneously) thought of as the sole tool of

mitigation.

7 In some situations, land-use planning measures can be more politically acceptable than are broad-based building codes (as is the case in

Salt Lake County, Utah.). However, such measures are adopted because they are extremely limited in geographic scope, and thus affect a relatively small number of buildings and structures.
104 I Reducing Earthquake Losses

The classic use of land-use planning to combat seismic hazards is California’s Alquist-Priolo Act of 1972,

This ordinance, which applies to the local government permit process for new construction, seeks to prevent

structures from being built atop active earthquake faults. Its origins lie in the historical prevalence of active

fault rupture (see chapter 2) in major California earthquakes, and reflects a belief that buildings and structures cannot be engineered to be resistant to fault motion. In concept, the act represents land-use planning in

its purest form, and practical details of the act therefore illustrate basic problems in implementation.

The basic form of the Alquist-Priolo is as follows: the State of California, through its Division of Mines

and Geology, identifies active faultlines and defines the land on and immediately adjacent to the faultlines

as “Special Study Zones. ” These zones are typically 600 feet to a quarter mile wide, with the width reflecting the degree of uncertainty over fault location and the amount of secondary fracturing of the ground on

either side of the main fault. Those wishing to build within a study zone must submit a licensed geologist’s

report detailing the existence of active faults near the building site. If an active fault is found, buildings

must be ‘(set back” from the fault (the amount of setback ranging from 10 to 50 feet, depending on the

nature of the fault). In this manner, buildings are not sited where they are not expected to survive.

Though the Alquist-Priolo is straightforward in concept, practical matters of execution somewhat weaken its impact. The philosophical justification for the act is the government’s responsibility to safeguard human life, and the legislation is therefore targeted at occupied structures. Structures occupied less than

2,000 person-hours per year are therefore exempt—an exemption that leaves out most lifeline system components (also exempt are single-family dwellings of wood frame construction, which though not resistant to

fault motion, are less likely than other building types to fail in a lethal fashion). In addition, local expertise in

geologic matters is required for successful implementation, as direct review authority over the required

geologic reports is left to local governments.

Finally, the Alquist-Priolo contains a purely informational component, whereby a buyer of property that

lies in a Special Study Zone is supposed to be informed of that fact. This provision of the act has been

found to be largely ineffective in influencing buyer behavior.

SOURCE: Robert Reitherman, “The Effectiveness of Fault Zone Regulations in California, ’’ Earthquake Spectra, voI 8, No 1 (Oakland,

CA Earthquake Engineering Research Institute, 1992), pp. 57-78

Seismic codes, however, are not a panacea. In

practice, their use involves a number of decisions

and tradeoffs that can collectively reduce their impact:

Seismic building codes do not govern every aspect of a community’s building stock, but typically focus on specific parts of specific building

types (thus ignoring certain aspects of building

damage and economic loss).

Codes cannot serve as a substitute for seismic

engineering expertise, and indeed require skill

and judgment on the part of their executors.

Elements of the code adoption process (the

steps that translate a seismic engineering recommendation into a specific code at the local

level) often reduce code performance from the

engineering ideal.

■ Effective local enforcement of the code is crucial for reducing risk.

These points are discussed in turn.

Code coverage and philosophy

Although in theory codes can be written so that all

buildings in a community are completely built to

seismically resistant standards, in practice their

application is more selective. Because the application of building codes involves a cost in money

and effort, prioritization is necessary, and not all

buildings and not all parts of buildings are treated

equally.
Chapter 4 Implementation 1105

A region subject to infrequent but potentially sizable earthquakes, the Salt Lake County of northern Utah

(an area containing metropolitan Salt Lake City and some 40 percent of Utah’s total population) uses landuse planning measures to reduce the impact of future damaging earthquakes. The intent of these measures is not to safeguard the general population, but to reduce the vulnerability of the built environment in

unusually hazardous areas. This approach in part reflects the historical lack of seismic activity in the region

and the consequent low public awareness of earthquakes and earthquake hazards: while broad-based mitigation measures such as new-construction building codes have engendered active regional opposition

(because of feared mitigation costs), geographically limited land-use decisions—which are typically made

by a small number of governmental and professional individuals—are less visible to the general public and

hence inspire less controversy.

The centerpiece of the county’s mitigation strategy is the Salt Lake County Natural Hazards Ordinance

of 1989. Significantly, this ordinance does not treat earthquakes in isolation. Instead, seismic concerns are

tied in with other natural hazards such as flood, landslide, and avalanche. This tactic allows the less common hazards--of which earthquakes are perhaps the rarest—to be handled by the same procedures that

govern the most common, a move that further reduces opposition to the measure while minimizing additional implementation cost.

In outline, the ordinance works as follows: geologic and microzonation studies (some funded through

the National Earthquake Hazards Reduction program (NEHRP) and the U.S. Geological Survey) are used to

identify particularly dangerous “hazard zones. ” Those seeking to develop sites within those zones can be

required to prepare a special engineering geology study delineating all of the local natural hazards and

explaining how the hazards will be dealt with (the nature of the hazard zone and the Intended use of the

site dictate whether a study is called for). The study must then be reviewed by the county geologist, the

Utah Geological Mineral Survey, and the Forest Service (in cases of avalanche threat), following which final

approval must be obtained by the county’s planning commissions.

The hallmark of this ordinance is extreme flexibility-a flexibility cited by county planning staff as crucial

to the measure’s success. With one exception (no buildings can be placed astride an active fault), the

ordinance does not require any specific mitigation action. Developers are therefore free to develop their

own mitigation tactics, be it through land-use measures like fault setbacks or through some engineering

response. This flexibility is another factor favoring public acceptance of the ordinance, and is felt appropriate to the region’s often complicated geology.

In turn, a flexible ordinance requires scientific and technical expertise on the part of county officials

tasked with reviewing the engineering geology studies (and further demands that reviewers actively use

their authority to halt unsatisfactory projects). Earlier incarnations of the ordinance were felt to suffer in

effectiveness because this expertise was lacking. In this light, a critical contribution was made to regional

mitigation efforts through NEHRP funding of a County Geologist Program from 1985 to 1988 This program,

which placed a geologist on the staff of the Salt Lake County Planning Department to improve the geologic

review process, was deemed so successful that the county chose to maintain the position following the

expiration of federal funding.

SOURCES: Philip R. Berke and Timothy Beatley, Planning for Earthquakes: Risks, Politics, and Policy (Baltimore, MD The Johns Hopkins Universty Press, 1992), pp 40-62; and Carlyn E. Orians and Patricia A. Bolton, Earthquake Mitigation Programs in Ca//forn/a,

Utah, and Washington (Columbus, OH: Battelle Human Affairs Research Centers, 1992), pp. 59-60, 69-70
106 I Reducing Earthquake Losses

Nonstructural damage-which most building codes do not

address-can be considerable.

First and foremost, the seismic portion of a

building code typically deals only with the building’s so-called structural components (i.e., the

frames, columns, beams, and load-bearing walls

whose failure can lead to building collapse and

consequent loss of life). Moreover, the structural

components are not necessarily intended to survive a strong earthquake unscathed: if the component is damaged but does not collapse, the code is

considered to have done its job. In other words, a

code-complying building can “survive” an earthquake (i.e., not collapse and kill people) and still

end up a shambles inside and out. This structural

emphasis is in part philosophical, since the original intent of seismic codes is to safeguard human

life. However, it also reflects a realization that

greater levels of building protection entail greater

construction costs.

Besides making a distinction between structural and nonstructural components, building codes

distinguish in terms of building use. In general,

structures that serve critical functions (e.g., hospitals) or house large numbers of people (e.g.,

schools) are held to a higher standard than are less

important, more thinly occupied buildings. These

distinctions again reflect the life safety focus of

most codes and the great cost of more broad-based

mitigation.

Because current codes are thus directed toward

life safety, they have only an indirect impact on reducing economic loss. For one thing, the function

or occupancy of a damaged building has little direct bearing on its cost of repair or replacement,

and a focus on high-occupancy or critical facilities

can leave vulnerable many less critical but costly

structures. In addition, nonstructural building

components such as stairwells, interior walls,

ceilings, plumbing, and fixtures can be both dangerous and expensive in their own right (see table

4-l).

Concerns over earthquake-induced economic

losses have led some to propose that the focus of

seismic building codes be broadened to encompass more than issues of strict life safety. Overall

damage reduction could then be pursued through

the targeting of nonstructural as well as structural

building components, or through the specification

of minimum levels of post-earthquake building

“functionality.” In principle, such changes could

be accomplished—although at some additional

cost. As noted in chapter 3, however, the knowledge base for this is not yet well developed, and

there is the chance that increased code complexity

will cause its own problems (e.g., by perhaps aggravating already formidable problems in code

enforcement).

Codes: no substitute for knowledge of

seismic engineering design

Although a great deal has been learned in recent

years about the design and construction of earthquake-resistant structures, most buildings are in

fact designed by local architects and engineers far

removed from the cutting edge of research. Some

way must therefore be found to transfer knowledge and experience from the researcher to the

practicing designer.

When resources are abundant, the knowledge

transfer process can be direct. If the expense is

warranted, one can require that a proposed structure be subjected to rigorous seismic engineering

analysis by specialists in seismic design—that is,

knowledgeable individuals with a professional

obligation to stay abreast of developments in their

field. Such an approach has the advantage of directly exposing the design process to individuals
Chapter 4 Implementation 1107

Exterior elements

Interior elements

Mechanical, electrical,

plumbing elements

Contents

Cladding, veneers, glazing, infill walls, canopies, parapets,

cornices, appendages, ornamentation, roofing, louvers,

doors, signs, detached planters.

Partitions, cellings, stairways, storage racks, shelves, doors,

glass, furnishings (file cabinets, bookcases, display cases,

desks, lockers), artwork.

and Heating, ventilation, air conditioning equipment, elevators,

escalators, piping, ducts, electric panel boards, life-support

systems, fire protection systems, telephone and communication systems, motors, emergency generators, tanks, pumps,

boilers, Iight fixtures.

Electronic equipment, data-processing facilities, medical

supplies, blood bank inventories, hazardous and toxic materials, museum and art gallery displays, office equipment.

SOURCE: H.J. Lagorio, Architectural and Nonstructural Aspects of Earthquake Engineering (Berkeley, CA University

of California at Berkeley, Continuing Education in Engineering, Extension Division, July 1987)

well versed in seismic principles, and is one often

applied to major structures such as skyscrapers or

nuclear powerplants.

The drawback of the engineering analysis approach is, of course, cost. Cost considerations are

such that most buildings in the United States are

constructed without the direct input of a seismic

engineering specialist, and many of the smaller,

more mundane structures (e.g., single-family

dwellings) are “unengineered’’ -that is, designed

without any formal engineering input. For such

buildings, seismic knowledge transfer can be accomplished through a code. Larger structures are

governed by code guidelines that lead nonseismic

engineers and architects through the design process; for smaller buildings, the codes offer specific,

written requirements for how structures should be

built. Such codes, which attempt to incorporate

seismic design principles into buildings too small

or inexpensive to warrant the involvement of a

licensed structural engineer, in theory would

require no specialized seismic engineering knowledge. That is, a competent builder or architect

unversed in seismic engineering should, by following the code, be able to produce a structure that

will not fall down in an earthquake.

In practice, however, the application of codes

by competent but seismically unversed individu -

als will not always be successful. The reason for

this failure is the need for flexibility within a

building code. That is, although it is possible to

write a “cookbook” code that unambiguously

spells out exactly how a building should be built,

such a code would be unworkable because:

Successful results are most likely when the

overall design of the building is of a type anticipated by the code writer—if the building is innovative or somehow out of the ordinary, the

code may simply not apply.

More fundamental] y, a cookbook code does not

allow architects and engineers the flexibility to

overcome the many unique obstacles that arise

in designing buildings and structures.

Because of these concerns, building codes are

written so as to give latitude for interpretation

while providing some guidance for the inexperienced. Thus it is possible for the seismically inexperienced to rigorously follow a code, cookbook

fashion, but still arrive at a vulnerable design.

In short, real-world variety in building design

and construction requires that building codes be

flexible, and this flexibility in turn requires that

judgement be exercised in code execution. Thus

building codes can work as intended only when

working designers and building officials pos-
108 | Reducing Earthquake Losses

sess an adequate understanding of seismic design and engineering.

Code adoption process

The preceding discussion presupposes that seismic building codes are actually used in the design

and construction of new buildings. How well a

code works, however, is of little import if the code

is never used. Local and state jurisdictions have

considerable discretion over the content of their

building codes, and many at-risk areas of the

country have chosen to incorporate seismic codes

only in part or not at all. The politics and economics of code adoption can thus have a greater impact

on seismic safety than do technical issues of code

performance.

The process of code adoption is as follows:

 The fruits of research sponsored by NEHRP

and other organizations are distilled into a

collection of reference documents, most notably:8

1. NEHRP Recommended Provisions for the

Development of Seismic Regulations for

New Buildings, Federal Emergency Management Agency (informally referred to as

the NEHRP Recommended Provisions);

2. Minimum Design Loads for Buildings and

Other Structures, ASCE-7-93, American

National Standards Institute; and

3. Recommended Lateral Force Requirements

and Tentative Commentary, Blue Book,

Structural Engineers Association of California.

 These documents, which give suggestions for

the stress or force levels that a building must

withstand, along with “detailing requirements”

that specify the design and construction of critical joints and structural elements, are not building codes. They are instead recommendations

that may be incorporated by regional code organizations into idealized “model codes,” the

most well-known of which is the Uniform

Building Code (UBC) of the International

Committee Conference of Building Officials,

which is used by much of the western United

States. (Other model codes include the Southern Building Code Congress International used

by southeastern states, and the Building Officials and Code Administrators code used in the

northeast United States.)

 Although a model code such as the UBC is in

fact a real building code, it does not directly

govern the construction of any buildings.

Instead, state or local authorities may choose to

incorporate it wholly or partly into the codes

actually used within their jurisdictions.

There are thus a number of hurdles to be overcome between the creation of a seismic code provision and its implementation. At the highest

level, that of the recommended provisions,

considerable effort is made to maximize the

provision’s cost-effectiveness and political acceptability. A successful effort will enhance the

provision’s acceptability and hence its chances for

eventual adoption, but the necessary changes have

the effect of making codes minimal, rather than

optimal, requirements. At the intermediate level,

model code organizations may pick and choose

among the recommended provisions in order to

meet their members’ economic and political concerns. At the end-use level, states and localities

will apply their own criteria as well in adopting

the model code. The result can be a wide gap between a NEHRP provision and an actual state

or local code.

Code enforcement: a continuing problem

Finally, the existence of a local building code does

little good if it is ignored when the building is designed, and code compliance in a building plan is

similarly irrelevant if the actual construction of

the building bears little relation to the design.

These failings do not imply dishonesty or malicious intent. Simple calculation errors at the de8 Henry J. Lagorio, Earthquakes: An Architect’s Guide to Nonstructural Seismic Hazards (New York, NY: John Wiley & Sons, Inc., 1990),

p. 246.
Chapter 4 Implementation | 109

sign stage, for example, can result in a weakened

building, and construction elements such as plywood shear walls can be rendered useless by

sloppy nailing. To guard against these and other

failings, a community concerned with seismic

safety must invest resources into code enforcement.

Building code performance therefore requires

that plans and the actual construction process be

checked by competent inspectors. Unfortunately,

few data exist on the performance of local plan- or

code-checkers, but anecdotal evidence from

California’s Northridge earthquake and from

Florida’s Hurricane Andrew suggest that problems of code execution and compliance result in

significant economic losses.9 The problem is

poorly documented but broadly recognized, and

represents an area in which improved performance can have benefits beyond simple seismic

safety (e.g., improved code enforcement has the

potential to lessen losses from wind and fire as

well).

In summary, building codes for new construction, although relatively popular and potentially

powerful, are no silver bullet: they generally cover

only structural collapse, they still require some

level of seismic engineering knowledge in order

to work well, they might not reflect the latest

thinking as captured in model codes or NEHRP

provisions, and they must be enforced.

Retrofit or Demolition of Existing Structures

Despite the problems that can beset code implementation, building codes for new construction

remain a powerful tool for improving the safety of

the built environment. However, when a community has a substantial older urban core and the risk

of an earthquake is immediate, the codes may

work too gradually. Since the average new building will typically stand for 50 to 100 years before

replacement, a community can expect about 1 to 2

percent of its building stock to be replaced each

year (more, if the community is expanding and

flourishing; less, if it is economically stagnant).

Thus if a damaging earthquake strikes within a

few decades of a code’s adoption, large parts of the

building stock will be caught unprepared. A concerned community might therefore consider the

most unpopular and contentious of mitigation

measures—retrofitting or demolishing vulnerable

existing structures (i.e., older structures that do

not comply with the latest version of the code).

The unpopularity of this option is manifold.

One problem is cost: unlike the case of new

construction, in which code compliance adds

some 1 to 2 percent to the total building cost, a retrofit/demolition plan can entail enormous expense. Retrofitting an unreinforced masonry

building, for example, will generally cost onequarter the price of a new building (and can in

some cases cost much more),10 while demolition

and replacement will of course cost full building

value. Such expenditures understandably instill

resistance on the part of building owners or anyone else who must bear the expense. In addition,

the money spent is not necessarily recouped in the

event of an earthquake: retrofits are primarily intended to prevent building collapse, and in some

instances a retrofitted building can be just as vulnerable to expensive nonstructural and contents

damage as an unmodified structure.

In addition to economic issues, there are considerable objections based on quality-of-life and

demographic concerns. Unreinforced masonry

buildings, potentially the most dangerous existing

buildings, are structures that form much of the urban core of many U.S. cities. They are often prized

for two very different reasons: 1) they can embody

much of the architectural heritage and character of

a city, and 2) they tend to provide most of the lowcost housing used by lower income groups. Demolition is therefore unpopular from both an

9 Although current life safety-oriented codes cannot eliminate economic losses, they do—by preserving the structural integrity of buildings—have an often significant impact on direct economic losses.

10 See chapter 3, “Damage to Buildings,” for references and assumptions.
110 | Reducing Earthquake Losses

architectural and a housing point of view, while

retrofits can lead to rent increases that drive away

the original residents. For these reasons alone, city

planners may hesitate to take such action, particularly where (as in the central United States) there

is great uncertainty about the timing of future

earthquakes.

Private, Small-Scale, and

Systems Preparation

The three mitigation tools discussed above—

land-use planning and zoning, new construction

building codes, and retrofit and demolition programs—primarily affect the structural integrity of

the built environment. If the primary concern is to

reduce loss of life, these tools may suffice. However, they are not enough to curtail major economic losses in the event of a damaging earthquake.

Recent experience (e.g., the 1989 Loma Prieta

and the 1994 Northridge quakes) has shown that

structural collapses, although spectacular and

newsworthy, are by no means the only source of

earthquake-related losses. Economic losses also

stem from business interruptions; loss of records

and computer databases in the service economy;

disruption of roadways, utilities, and other lifelines; and widespread, noncatastrophic damage to

residential and commercial structures throughout

the earthquake region. Although it is difficult to

quantify the effect of these losses (particularly in

the case of indirect economic damage), their significance is suggested by one estimate of direct

residential losses in future earthquakes. This estimate implies that catastrophic building failure,

which is what codes and retrofits are designed to

prevent, will be responsible for less than one-tenth

of California’s future bill for direct earthquake

losses.11 Even neglecting the potentially significant issue of indirect losses (i.e., those pertaining

to the disruption of business and services), we

thus find that traditional mitigation tools of landuse planning, retrofits, and building codes can be

largely undirected at reducing the economic impact of a major earthquake.

To mitigate against economic damage, a community must therefore encourage a varied assortment of measures that are collectively referred to

in this report as “private, small-scale, and systems

preparations.” These are measures adopted primarily by individuals, corporations, and utilities

to reduce the economic losses caused by various

nonstructural failures. The distinction between

these measures and structural tools is somewhat

arbitrary (e.g., structural building codes can help

reduce nonstructural damage, and lifeline-related

losses ultimately stem from the failure of bridges,

dams, and other structures). However, as a group

the measures are ones requiring motivation, careful thought, and tailoring of strategy by individual

end users, and as such are not well suited to broadbrush, mandated approaches.

Examples of such measures are:

 Encouraging individual developers and building owners to adopt design and construction

techniques that exceed code requirements. As

noted earlier, codes serve as a minimum standard, and future structural and nonstructural

damage might be averted if a structure is built

to a higher level of performance.

 Developing, before a damaging earthquake,

contingency plans for rerouting traffic, dispatching emergency crews, establishing alternative water, power, and supply sources, and

otherwise taking action to reduce post-earthquake indirect losses. Such activity, which requires considerable time, expertise, and

coordination, can be taken by both governmental and private entities.

 Motivating individuals, businesses, and organizations to systematically identify their own

earthquake vulnerabilities and to take appropriate action. These actions can range from

securing bookshelves and waterheaters by

homeowners, to elaborate efforts on the part of

11 Risk Engineering, Inc., “Residential and Commercial Earthquake Losses in the U.S.,” report prepared for the National Committee on

Property Insurance , May 1993, p. 17.
Chapter 4 Implementation | 111

businesses, hospitals, schools, museums, and

utilities to establish redundancies of power,

services. computer databases, and the like.

Success in these efforts can work greatly to reduce the damage, injuries, and general chaos that

may accompany earthquakes. The difficulty is

that such efforts require diligent action on different fronts by different players, many of whom

may care little about mitigation. Complicating

matters is that most of these efforts require for

their success that other measures be successful as

well. For example, computer backups do little

good if the computer resides in a building that collapses, and a single unsecured water heater can set

an otherwise diligent neighborhood ablaze. Success thus depends on the community possessing a

broad, active, and sustained level of public interest in mitigation.

■ Devising and Fostering Action

Once a community has decided on its choice of

mitigation measures, it must put those measures

into effect. The simplest action is to require

(through regulation or mandate) that certain steps

be taken. Such an approach, however, risks alienating the affected constituency (particularly in

cases such as building retrofit or demolition,

where high mitigation costs might be borne by a

small group of individuals). Thus, in practice,

many communities have chosen to develop alternative implementation strategies using financial

or zoning incentives for mitigation, or (more

weakly) through notices and disclosure laws

warning potential renters or buyers of a building’s

noncompliance. Experience has generally shown

that for success to be achieved, implementation

schemes must be tailored to the particular political, socioeconomic, and geological conditions of

a specific at-risk community, and that great pains

must be taken to involve (as much as is possible) a

broad-based constituency. Some possible approaches are illustrated in boxes 4-1 through 4-4.

One potentially powerful implementation tool—

the use of insurance to encourage the adoption of

Many earthquake losses cannot be eliminated through codes

or other governmental measures, but require that individuals

take steps to prepare.

seismic mitigation—is not discussed because of a

lack of historical experience.

FACTORS AFFECTING IMPLEMENTATION

In the preceding section, some of the practical difficulties that arise in putting mitigation tools into

effect are discussed. This section focuses on several underlying issues that more fundamental y influence implementation success.

■ Basic Problems

Communities interested in mitigation can encounter many frustrations in determining their

level of seismic risk, in estimating their vulnerability to that risk, in assessing the short- and

long-term economic consequences of mitigation,

and in putting mitigation tools into effective action. Such difficulties arise even in the relatively

straightforward process of improving life safety
112 I Reducing Earthquake Losses

After California’s San Fernando earthquake of 1971, in which buildings of unreinforced masonry (URM)

construction experienced substantial damage, the nearby city of Los Angeles began considering ways of

safeguarding its own URM building stock. Action was initiated in February 1973, via a city council motion to

study the feasibility of seismic “building rehabilitation, ” but eight years would pass before the landmark

Los Angeles Seismic Ordinance finally became law. The twists and turns on the road to this ordinance—

and the at times surprising impact it has had on local land-use patterns—illustrate some of the issues that

can arise in the implementation of seismic retrofit programs.

Initial Action

Seismic retrofit action in Los Angeles was prompted by the San Fernando experience, by the 1971 passage of an earthquake hazards reduction ordinance in nearby Long Beach, and by the recognition that the

city possessed many thousands of old, potentially vulnerable URM structures, many of which were extremely densely occupied. Concerns centered on life safety issues, with little priority given to minimizing

earthquake-induced economic losses, and early attention focused on high-density, public-assembly buildings such as churches and movie theaters. This philosophy of targeting a select group of high-vulnerability

structures quickly ran afoul of such community groups as architectural historians, who feared the demolition or visual modification of many of the city’s historical landmarks, and groups such as the Association of

Motion Picture and Television Producers, which felt that seismic ordinances would force the bankruptcy

and closure of many marginal theaters (particularly since the proposed ordinances were combined with

compliance requirements for structural, electrical, and fire safety codes from which the buildings had hitherto been exempt).

Vigorous community opposition to the proposed ordinances therefore led to the holding of public and

city council meetings from 1974 through 1976. Following these meetings, it was decided to target only the

most potentially catastrophic buildings: pre-1 934 URM assembly buildings that could contain over 100 occupants in the assembly areas. Because of continued concern over the financial implications of seismic

retrofit (contemporary estimates placed retrofit costs at amounts comparable to the cost of an entirely new

building), recommendations were also made that the retrofits be in part publicly funded by federal and

state grants (for which lobbying efforts were initiated), low-interest loans, or tax incentives.

Work on establishing forms of financial assistance proceeded through 1976, but progress was Impeded

by a combination of legal and engineering difficulties. One problem was that governmental assistance to

churches or other sectarian-use buildings was deemed unconstitutional; another was a growing realization

that very little was known about the true costs of seismic retrofit.

After three years without progress, an interim proposal in October 1976 suggested that the 14,000-odd

buildings to be targeted by the eventual ordinance be prominently signposted as seismically hazardous

By posting such information, the city hoped to invoke market forces for mitigation (by reducing market

demand for vulnerable structures) before the start of seismic retrofit. This information-based proposal was

strongly attacked by a host of citizen groups, among them the Hollywood Chamber of Commerce, apartment house owners, owners of commercial properties, and private attorneys. All expressed outrage and

concern over possible effects on rents, property taxes, insurance rates, real estate sales, bank financing

for renovations, lost jobs, and local economic development. Faced with this overwhelming opposition, the

city tabled the proposal and redirected its efforts to the core components of the ordinance.
Chapter 4 Implementation | 113

At this point in the controversy, studies were commissioned to determine the economic and social impacts of different proposals. Key issues included the breadth of the eventual ordinance (e.g., it was decided early on to cover a wide range of commercial and private building types, but to exempt single-family

residences); the amount of time a building owner would be given to comply, the rapidity with which the

program would be phased in and the prioritization given to different buildings and building types; and the

type, availability, and impact of different financial assistance schemes. By 1978, these studies had identified specific concerns for the city council to address, among them: a continued lack of accurate retrofit

cost estimates; a real possibility of substantial insurance premium hikes in the region, a significant likelihood of rent increases that would displace low-income residents; an insufficient municipal tax base for financial assistance (Proposition 13 had recently been passed); and an expectation that some businesses

displaced during retrofitting would leave the city entirely.

Final Passage

With most of the concerns identified in the studies of 1977 to 1979 revolving around the economics of seismic rehabilitation, a breakthrough eventually occurred when three old URMs were found to stand in the

path of a street-widening program. The city was persuaded to donate the three buildings for tests on the

true costs of seismic retrofits. These tests, which were completed by 1980, showed retrofit costs to represent only about 20 percent of replacement costs—far less than had previously been suggested—and in so

doing significantly weakened the economic objections to the proposed ordinance.

At last, after more lengthy debate, a seismic safety ordinance was formally adopted by the city on January 7, 1981—almost a decade after the initial impetus of the 1971 San Fernando earthquake. In its final

form, the ordinance targeted all commercial URM structures and all residential URM buildings housing five

or more dwelling units. After being notified by the city, owners of targeted buildings would have three years

in which to bring their structures up to standard (this standard represents some 50 to 70 percent of the

1980 Los Angeles requirements for new construction). Buildings not brought up to standard would be demolished. To ease the impact on building owners and to facilitate bureaucratic execution, the ordinance

allowed a one-year compliance extension should wall anchors (see chapter 3) be installed within the first

year, and used a staggered notification schedule based on building type. Essential and high-risk facilities

were to be targeted first, with lower risk structures to be dealt with later; as a result, some owners of lowrisk buildings were not to receive official notification until 1988.

Impact of the Ordinance

From a seismic mitigation viewpoint, the Los Angeles Seismic Ordinance can be viewed as a success.

Though the process has been more protracted than proponents might wish, a seismically vulnerable urban

core is being prepared against the near-certainty of future earthquakes in the region. Should a damaging

earthquake strike Los Angeles in the near future, it IS extremely probable that many Iives will have been

saved by this measure. However, the ordinance has also generated side effects. Most notable has been

the loss of low-cost housing, arising from owners raising rents in an attempt to recover out-of-pocket retrofit

expenses. In addition, architectural and historic preservation has suffered-not because of building demolition (generally forbidden by historic building codes), but because of partial demolition, the removal of

architectural ornamentation, and the filling in of windows.

(continued)
114 I Reducing Earthquake Losses

Perhaps the most surprising development

has been a change in the overall appearance

of some URM-lined streets, a change stemming from an unexpected interaction between

seismic and fire safety regulations: noncompliance with existing fire safety codes has led

many URM owners to close the upper floors

(thus avoiding the cost of code compliance),

and bring to compliance only the higher rent

street level for use by commercial establishments (this partial vacancy is possible because fire safety codes need apply only to the

occupied parts of a building). Because seismic retrofit must be applied to entire buildings—which means that vacant, nonproductive floors must be strengthened along with

floors that are actually occupied—many of

these URM owners have chosen to remove

the upper floors entirely, leaving behind only

single-story structures. Aside from aesthetic

considerations, such removal further reduces

the potential low-cost housing stock within the

city’s urban core.

SOURCES: Daniel J. Alesch and William J. Petak, The Politics and Economics of Earthquake Hazard Mitigation

(Boulder, CO, University of Colorado Behavioral Science,

1986), pp. 57-82; and Martha B Tyler and Penelope

Gregory, Strengthening Unreinforced Masonry Buildings

in Los Angeles: Land Use and Occupancy Impacts of the

An unexpected side-effect of the Los Angeles seismic retrofit

program was the partial demolition and conversion of

multistory buildings into low, single-story structures

I

L.A. Seismic Ordinance (Portola Valley, CA William Spangle and Associates, Inc., 1990)

through building codes. When the goal is to re- tivity. Outside California, matters are generally

duce economic losses—which requires a much

more comprehensive effort by both governmental

and nongovernmental entities—the uncertainties

are even greater.

Given these uncertainties, it is perhaps not surprising that many communities have encountered

diffilculties in implementation. The problems are

not insuperable in California-where earthquakes

are frequent and severe enough to foster a desire

for action—but even there one finds substantial

variations in preparedness among different communities, and substantial difficulties persist in

areas of retrofit and private or organizational acworse: in many hazardous regions, a relative lack

of historical seismic activity produces a consequent lack of concern, so that even basic mitigation efforts languish.

■ Administrative Difficulties

In response to this inactivity, NEHRP has sponsored social science research on how and why

communities act or fail to act. This research has

shown that a number of forces conspire to weaken

community will. Some of the difficulties stem

from poor experience with existing mitigation ef-
Chapter 4 Implementation 1115

While several communities in southern California have attempted mandatory retrofit and demolition programs to reduce the seismic vulnerability of urban centers (see box 4-3), the northern California city of

Palo Alto has recently introduced a wholly voluntary, information- and incentive-based seismic retrofit program that is showing some early signs of success.

The origins of Palo Alto’s voluntary program lie in two failed attempts at introducing mandatory, Los Angeles-style requirements. The first, a 1982 proposal targeting 250 unreinforced masonry, tilt-up (see chapter

3), and other vulnerable structures, succumbed to strong opposition from affected building owners and tenants. Following the defeat of this ordinance, the Palo Alto city council formed a broad-based citizen’s Seismic

Hazard Committee representing a range of public and private interests. This committee was intended to devise a second hazard mitigation plan that would reflect the concerns of the general community. However, the

creation of the committee had the effect of greatly heightening community awareness of local seismic risk and

hazard, with the consequence that the second proposal (in 1983) was far stronger than the first. This, too,

went down in defeat—in part because of an inflexible retrofit timetable, and in part because proponents of the

measure were hampered by extreme uncertainties regarding building vulnerability and the potential economic impacts of the ordinance. In light of these uncertainties, it was suggested that a voluntary program be

instituted, one that would allow building owners to judge whether retrofit was economically justified, and one

that would permit flexibility of approach and timing.

In 1986, a seismic ordinance was therefore passed in which no buildings were mandated for retrofit or

demolition. The provisions of this ordinance areas follows: at-risk structures (particularly those with high occupancy) are identified and their owners given official notification. Following notification, building owners are

required to contract with a structural engineer to evaluate building vulnerability and to suggest appropriate

engineering fixes. Owners do not have to carry out the suggestions; however, they are required to inform

building occupants in writing that an engineering study has been performed and that the results have been

publicly filed with the city. In concert with the city’s relatively high level of seismic awareness (fostered by the

high education level of the citizenry, the work of the Seismic Hazard Committee, the presence of well-placed

mitigation advocates within the local government, and extensive media coverage of earthquake disasters

elsewhere), this notification is intended to affect rental and real estate prices in the city’s highly competitive

market. A March 1988 review of the program suggested that this market incentive is working as planned. To

further increase the incentive, the city has also offered a zoning bonus, in which seismically upgraded buildings are allowed greater floor areas than is otherwise the norm. This bonus (again in concert with the city’s

strong economic health) also appears to be effective, to the extent that building owners who are unaffected by

the program have sought (unsuccessfully) to obtain the bonus by having their own buildings included.

SOURCE: Philip R Berke and Timothy Beatley, Planning for Earthquakes: Risks, Politics, and Policy (Baltimore, MD: The Johns Hopkins University Press, 1992), pp. 63-81.

forts, which can suffer at the state and local level ■ overly stringent reporting, oversight, and apfrom:

■

■ a lack of scientific and technical information in

a form that local governments and private industry can easily use;

proval requirements; and

tasks that require more staff resources than are

available (typically, implementation duties are

assigned to but one or two persons in a state office). 12

12 VSP Associates, Inc., “State and Local Efforts To Reduce Earthquake Losses: Snapshots of Policies, Programs, and Funding,” report

prepared for the Office of Technology Assessment, Dec. 21, 1994.
116 | Reducing Earthquake Losses

More fundamentally, existing state and local

efforts can suffer from a lack of hard information

on earthquake risks and potential impacts. A recent survey of state activities has shown that

across the risk spectrum, studies of historical

earthquake activity and assessments of current

vulnerability are the two types of information

essential to raising awareness, understanding,

and commitment to seismic safety.13

❚ The Role of Advocates

Despite the difficulties that beset state and local

mitigation efforts, considerable progress has been

made by a number of concerned communities.14

In many instances, this progress arises from the

presence of well-placed mitigation “advocates”—energetic, often exceptional individuals

in state or local government who adopt and push

the cause of mitigation. Such advocates do not

work in isolation. Rather, they can act as catalysts

for action in communities where local political

and socioeconomic conditions are conducive. Although their presence is not essential for action to

occur, advocates can have an impact completely

out of proportion to their numbers. Indeed, a number of cities owe the bulk of their mitigation progress to a handful of such individuals.15

❚ Political Will

The importance of individual advocates, however,

points out a larger problem besetting NEHRP:

earthquake mitigation advocates (successful or

not) are generally in the position of encouraging

activity for which there is little initial enthusiasm.

This reality has stern implications for efforts to reduce earthquake-related economic losses. While a

few well-placed advocates can help convince governments to adopt building codes or land-use

planning, they are less likely to create the groundswell of public action needed to substantially curtail future economic losses.

OTA’s review of the implementation process

has shown that effective mitigation depends on

competent, committed action by a host of different

individuals. This need is especially apparent in the

case of private, small-scale, or systems-related efforts, which require that people design and implement their own mitigation schemes. Yet it is also

true for the relatively straightforward use of building codes (i.e., an effective building code, adopted

in full by the state or local authority, interpreted by

engineers trained in seismic design principles, and

enforced by experienced plan and code checkers

working with the support of the local community)

(see figure 4-1). To some extent, the many players

in the chain can be persuaded or forced into action

(at least for a while), but as a whole, implementation is greatly enhanced if there is an evident and

sustained political will to support mitigation.

Such is often not the case in the United States.16

❚ Perceived and True Danger

of Earthquakes

Nonfederal support for seismic mitigation suffers

in part from the relation between earthquake risk

and geography. At the federal level, interest in

earthquake mitigation is sustained by a high prob13 Ibid.

14 The report prepared for OTA indicates that California, Kentucky, Missouri, Utah, Arkansas, Washington, and Oregon devote particular

attention to the formulation, adoption, and implementation of major policies. Ibid.

15 Joanne M. Nigg,” Frameworks for Understanding Knowledge Dissemination and Utilization: Applications for the National Earthquake

Hazards Reduction Program,” A Review of Earthquake Research Applications in the National Earthquake Hazards Reduction Program:

1977-1987, Walter W. Hays (ed.) (Reston, VA: U.S. Geological Survey, 1988), pp. 13-33; Philip R. Berke and Timothy Beatley, Planning for

Earthquakes: Risk, Politics, and Policy (Baltimore, MD: The Johns Hopkins University Press, 1992), pp. 32-34; and U.S. Geological Survey,

Applications of Knowledge Produced in the National Earthquake Hazards Reduction Program: 1977-1987, Open File Report 88-13-B (Reston, VA: 1988), pp. 20-22.

16 Peter H. Rossi et al., Natural Hazards and Public Choice: The State and Local Politics of Hazard Mitigation (New York, NY: Academic

Press, 1982), pp. 40, 71.
Chapter 4 Implementation 1117

Built

environment

NOTE Steps and players wiII differ for other types of mitigation measures

SOURCE Off Ice of Technology Assessment, 1995

ability of damaging seismic activity occurring

within federal jurisdictional borders. To the extent

that California bears the largest share of the country earthquake hazard, California state interest in

earthquakes is also reasonably strong (it is not

coincidental that California’s mitigation efforts

frequently surpass those of the federal government). For the rest of the country, however, the

risk 17 of earthquake activity in any one state is

considerably less than the nationwide risk borne

by the federal government, and everywhere the local risk declines further when one considers the

smaller governmental or organizational units. At

the extreme is the plight of the individual building

owner in a region such as the Northeast. This individual owns a structure that might never experience a damaging earthquake. If an earthquake

occurs, the building may or may not collapse. If it

does collapse, it is not certain that retrofitting

would have saved it.

In short, while the federal government may

have a legitimate interest in encouraging all building owners in the country to consider retrofits (on

the assumption that at least some of those retrofits

will do some good), an individual owner may see

very little reason to embark on a costly action

whose benefits are long term and uncertain. The

owner lack of interest maybe based on a very rational analysis of costs and benefits, but can also

be influenced by the short time horizon frequently

observed in analyses of consumer decisionmaking (sometimes expressed as a high consumer discount rate), an influence that has been well

documented in issues of energy efficiency,18 and

which has relevance to hazard mitigation. 19

17 Risk is used here as total exposure or potential for damage in an earthquake.

18 See, e.g., U.S. Congress, Office of Technology Assessment, Building Energy Efficiency, OTA-E-518 (Washington, DC: U.S. Government

Printing Office, May 1992), chapter 3.

19 H. Kunreuther, "The Role of Insurance and Regulations in Reducing Losses from Hurricanes and Other Natural Disasters,” Journal of

Risk and Uncertainty, forthcoming.
118 | Reducing Earthquake Losses

With perceived risk at the individual level often

very low, one can attempt to increase it through

skillful use of the media and educational outreach.

That the media can have significant impact on

earthquake awareness is unquestioned, and history has shown that extensive media coverage in the

aftermath of a damaging earthquake creates a temporary “window of opportunity” for rapid mitigation progress.20 The importance of these

windows—and the unpleasant reality that mitigation progress can easily stall after the window

closes21—has prompted research on how one may

best create a permanent perception of risk. Results

have thus far been mixed—for example, some

studies show that people already overestimate the

risk of rare events such as earthquakes,22 while

others suggest that low probability risks tend to be

ignored.23

❚ Role of NEHRP

Given the general lack of sustained public support

for mitigation, why does NEHRP depend so

heavily on the unforced adoption of mitigation

measures by nonfederal entities? In large part this

dependence stems from the scientific circumstances that surrounded the program’s birth. In

broad terms, NEHRP was created during a period

of optimism over the practicability of accurate

earthquake prediction, and its original program

mission (which specifically cites prediction as a

goal) reflects that optimism. At the time of

NEHRP’s founding, the earth sciences had just

emerged from a sweeping and profound revolution, one comparable to Darwin’s theory of evolution in its scope, impact, and ramifications. This

revolution was the advent of modern plate tectonic theory—a conceptual picture of the world that,

through the 1960s and early 1970s, succeeded in

tying together a host of previously unexplained

and seemingly unrelated phenomena from across

the earth sciences. Seismology—the study of

earthquakes and earthquake-related phenomena—played an integral role in the development of

plate tectonic theory; in turn, plate tectonics offered a simple unifying framework for understanding why, when, and where earthquakes

should occur. The decade of the 1970s was thus

one of extraordinary excitement in the earth

sciences, and in this climate it was felt that shortterm earthquake prediction, if not just around the

corner, was at least conceivable, and that steady

improvements in long-range earthquake forecasting would come with research.

The significance of this optimism from a policy

standpoint is that it favors a mitigation strategy in

which federal incentives for action are perceived

as unnecessary. As we have seen, uncertainties in

the timing, location, and severity of future earthquakes hinder both the acceptance and the execution of mitigation programs by nonfederal

entities. Successful earthquake prediction, in removing this uncertainty, improves matters by providing a clear motivation for action and by

delineating the intensity and geographic scope of

the necessary mitigation, thereby constraining the

cost.

In effect, a vastly refined foreknowledge of

how, when, and where earthquakes occur can

arguably be used to create both the desire and the

expertise for the implementation of mitigation

measures. In keeping with this philosophy,

NEHRP was given neither regulatory teeth nor the

authority to provide substantial incentives for mitigation. Instead, the program was intended to

create a font of knowledge from which nonfederal

20 U.S. Geological Survey, see footnote 15, pp. 27-28.

21 Berke and Beatley, see footnote 15, p. 178.

22 Andrew Coburn and Robin Spence, Earthquake Protection (Chichester, England: John Wiley & Sons, 1992), p. 315.

23 Daniel J. Alesch and William J. Petak, The Politics and Economics of Earthquake Hazard Mitigation (CO: University of Colorado, Institute of Behavioral Science, 1986), p. 142; and Dennis S. Mileti et al., “Fostering Public Preparations for Natural Hazards: Lessons from the

Parkfield Earthquake Prediction,” Environment, vol. 34, No. 3, April 1992, p. 36.
Chapter 4 Implementation | 119

authorities and the private sector would eagerly

draw.

Although it is debatable whether NEHRP

would have attained its societal goals even with

widespread success in earthquake prediction (given the implementation difficulties discussed

above), the fact is that prediction is not likely in

the near future. This development is not the fault

of the program. In fact, it is NEHRP-sponsored research that has begun to reveal just how complex,

unpredictable, and variable earthquakes and their

effects really are. Because of NEHRP we now

know far more about earthquakes and far more

about the structures and techniques that can withstand them. However, with this understanding

comes a better appreciation of how deep and stubborn are the remaining uncertainties—uncertainties that work against the nonfederal adoption of

mitigation measures.

HOW MATTERS MIGHT BE IMPROVED

The preceding sections have shown that implementation difficulties hinder both the adoption

and the execution of seismic mitigation programs;

these difficulties largely reflect the economic and

political cost of mitigation as seen against a backdrop of uncertain seismic hazard and vulnerability. In the current NEHRP structure, federal

activities to promote mitigation consist largely of

outreach, media, and educational programs; such

efforts may be expanded, or they may be supplemented by more aggressive implementation tactics (see chapter 1). Here, OTA suggests a range of

directions that can improve mitigation efforts.

The implementation needs of California are

largely different from those of the rest of the country. Within California, continual seismic activity

in a heavily urbanized state has led to significant

public and governmental awareness of earthquake

risks and hazards. This awareness has resulted in

California leading the country in mitigation and

preparedness efforts. Because California already

has in place a basic mitigation framework of new

building codes, selective policies of land-use

planning, and active public outreach programs

through schools and the media, the main implementation issue is execution, rather than adoption.

That is, although some adoption problems remain

(notably, the retrofit of “pre-code” buildings that

do not comply with the latest building standards),

for the most part one can concentrate on expanding and optimizing the mitigation efforts that are

already in play.

In contrast, regions outside California display a

broad spectrum of mitigation activity, ranging

from encouraging progress in some communities

of the Pacific Northwest, to low or nonexistent activity in many parts of the East Coast, central

United States, and Intermountain West. For some

of these areas, earthquake severity and timing are

such that seismic concerns are reasonably seen as

low priority (e.g., Boston). In others, potentially

high risks are masked by relatively short histories

of urban settlement and a relative absence of frequent, moderate-level seismic activity (e.g., the

Intermountain West). In concert with the extreme

levels of scientific uncertainty that seem to surround non-California earthquakes, these factors

have greatly inhibited the adoption of many mitigation measures.

Thus, in basic terms, one would hope to improve program execution in California while encouraging program adoption elsewhere. Efforts to

achieve these aims can be made in each of the three

NEHRP components: earth science, engineering,

and implementation.

❚ Earth Science Research Measures

Earth Science: Reducing Loss of Life

Earth science research efforts that can improve life

safety in future earthquakes fall into two broad

categories: basic research that will reduce the likelihood of “surprises” in the future size, location,

and timing of severely damaging earthquakes

(and in so doing, increase the likelihood that mitigation measures are adopted); and more directed,

microzonation-style studies to identify localized

troublespots. Both categories are of use throughout the country, although their roles vary subtly

according to geography.

In areas where implementation is currently

weak (i.e., much of the country outside of Califor-
120 | Reducing Earthquake Losses

nia), reductions in loss of life (and economic

losses) require that seismic building codes and

other mitigation measures be adopted by at-risk

communities. Because great uncertainties over

earthquake location, severity, and timing act as

a disincentive to action, the earth science priority here is for basic research that can better

zero in on when, where, and how strongly an

earthquake will strike. This research must not

only delineate where earthquakes are likely to occur (information that increases the perceived

benefit of mitigation), but also identify areas of

relative safety (which reduces the geographic extent—and thus cost—of mitigation).

Where there exists some degree of interest in

seismic mitigation, the potential importance of

microzonation-style research grows. In localities

where the earthquake danger is recognized, such

research allows communities to sidestep opposition to broad-based mitigation by narrowly targeting exceptionally hazardous sites (this is the

approach taken by Utah’s Salt Lake County Natural Hazards Ordinance, discussed in box 4-2).

More mitigation-friendly locales will likely use

such research to help prioritize efforts in seismic

retrofit and demolition; to identify situations in

which land-use planning is the most effective implementation option (i.e., places where no reasonable amount of engineering can overcome the

effects of catastrophic liquefaction, landslides, or

tsunamis); and to optimize building code provisions for the characteristics of future ground motions.24

Earth Science: Reducing Economic Losses

Although the importance of earth science research

for life safety is clear, its role in minimizing economic loss is somewhat less so. This uncertainly

stems from our lack of understanding of the true

sources of earthquake economic loss.

On the one hand, successful earth science research can reduce future economic losses in those

regions where mitigation activity is relatively

weak. Where mitigation measures are hampered

by uncertainty over risk and hazard, refined earthquake forecasts can encourage their adoption. In

addition, microzonation research can allow otherwise reluctant communities to direct their efforts

to geographically limited locales, thus fostering

adoption where there would otherwise be none. In

both cases, research can lead to loss reduction

through the encouragement of basic mitigation activity.

In regions where mitigation measures are already in place, however, continued earth science

research plays a more uncertain role. Because

such regions typically experience high seismic activity (e.g., southern California), sheer prudence

dictates that basic seismic research and groundmotion studies be continued so as to reduce the

likelihood of major surprises in earthquake location and severity (surprises that can leave even a

diligent community unprepared for a future calamity). However, in the absence of such surprises, there is the possibility that continued

research will beget diminishing returns. At issue

is the true source of earthquake economic losses:

if the bulk of such losses stem from episodes of

major damage, then refined earthquake and microzonation forecasts can reduce losses by permitting better targeting of vulnerable structures

(particularly if the research is directed toward lifeline survivability). However, if the majority of

earthquake losses stem ultimately from moderateto-minor ground-shaking damage distributed over

a wide area, then efforts to pinpoint local trouble

spots (as well as to refine estimates of earthquake

timing and location) will not address the major

source of economic loss. Uncertainty over the

true origins of earthquake-induced economic

24 Damage in the 1994 Northridge quake indicates that even moderate earthquakes can subject buildings to stresses far greater than have

been expected, and one must assume that larger quakes possess a similar potential. Credible ground-motion estimates, derived from microzonation-style modeling and from data collected in actual events, are therefore essential to writing effective building codes. However, such estimates

will be of use only if actively transmitted to the engineering community in a manner that recognizes the need for codes to be stable over time.
Chapter 4 Implementation | 121

losses therefore impede discussions of earthquake loss reduction, and remain an important

avenue for social science research.

❚ Engineering Research Measures

Engineering Measures: Reducing Loss of Life

From an implementation perspective, improved

life safety can arise from engineering research if

retrofit costs are brought down, and if better tools

are devised to assess building vulnerability.

Particularly in California, where new construction is reasonably well handled by codes,25 measures to save lives will center on older structures,

particularly buildings of unreinforced masonry.

Although many factors inhibit the systematic retrofitting of URMs and other noncomplying structures, a major obstacle to retrofit action is simply

cost. Successful research into more cost-effective

retrofit techniques—particularly if the techniques

can be shown to reduce post-earthquake repair

bills dramatically—can therefore make retrofit

programs more palatable both to local policymakers and to building owners.

Opposition to retrofit programs can be further

reduced if it can reliably be determined what

buildings do not need to be retrofitted. For example, not all URM structures display the same vulnerability to earthquake damage, and a means of

distinguishing the most vulnerable from the least

can permit a more selective targeting of structures.

Ongoing efforts to develop an analytic means of

making such distinctions can therefore enhance

program effectiveness while reducing the number

of affected building owners and occupants.

Engineering Measures: Reducing

Economic Losses

As noted above, current building codes focus on

structural issues while giving little attention to

nonstructural and contents damage. Because the

latter kind of damage can generate most of the economic losses that accompany damaging earthquakes, research into effective, low-cost methods

of reducing such damage might yield substantial

rewards.

It is unclear, however, how to best incorporate

nonstructural and contents damage concerns into

current building codes. One difficulty is that such

damage is often hard to proscribe in the language

of a prescriptive code (e.g., a code cannot easily

specify what steps a computer software company

must take to safeguard its data and records, nor can

it order individuals how to arrange furniture,

bookshelves, or cooking equipment). Because of

this limitation, one approach could be to replace

prescriptive building codes with performancebased standards (i.e., codes that provide great

flexibility of execution while requiring minimum

standards of seismic performance). Such an approach has been adopted with some success in the

construction of California hospitals, which are required to maintain functionality in the aftermath

of a damaging earthquake (however, these codes

are somewhat controversial in their need for

painstaking execution). By defining design options appropriate to different levels of safety or

performance, engineering research may increase

the odds that performance-based codes attain a

wider use.

A second approach to reducing economic

losses would be to concentrate on the indirect effects of earthquake damage. In particular, because

the federal government maintains some authority

over lifeline systems (e.g., transportation and energy), a potentially significant avenue for economic loss reduction lies in the “hardening” (i.e.,

strengthening and introducing redundancy) of

lifelines and vital response systems to reduce indirect losses and improve post-earthquake recovery.

Such a move would be assisted by research into

measures such as the preservation of potable and

firefighting water systems, or the use of automatic

shutoff devices on natural gas lines.

25 Subject to the limitations noted in this chapter, including problems of enforcement and limited coverage of economic damage.
122 | Reducing Earthquake Losses

❚ Direct Measures To

Improve Implementation

More direct efforts to improve implementation

will primarily involve education and outreach,

technical assistance to nonfederal governments

and organizations, and social science research into

the nature of implementation bottlenecks. These

efforts can be applied to the current implementation framework, or as preparation for a more vigorous federal mitigation role.

Actions that may assist implementation within

the current framework include the following:

 Because individual local advocates and concerned professional organizations can play a

powerful role in fostering and maintaining

community interest in mitigation, efforts to

create or assist advocates are of great potential

impact. The federal government can assist advocates in this area by: ensuring that advocates

have access to the latest information and educational materials on earthquake risks, supporting community activities as funding permits, or

supplying direct technical and educational assistance to local or state governments.

 The more publicity there is concerning earthquakes, the more likely it is for individuals to

become advocates. Thus media and public outreach activities can have a powerful indirect effect, both in fostering the appearance of

advocates and in creating a supportive environment in which they may act. Public interest in

earthquakes generally depends on how recently

a major quake has occurred, but preparing outreach materials to take advantage of disaster

windows is a prudent measure. Such outreach

is relatively inexpensive and potentially productive, although in places where destructive

seismic activity is extremely infrequent (e.g.,

the U.S. east coast), it is unlikely to create a

surge of local activity.

 Research into the political and social science of

mitigation success and failure can assist implementation by identifying stumbling points

(e.g., factors hindering code enforcement) in

the implementation process. Such research will

not likely be undertaken without federal support.

 Perhaps the most promising implementation

activity is to assist communities in their efforts

at understanding risk, vulnerability, costs,

benefits, and mitigation options. Workshops,

conferences, and forums have been and will

continue to be useful in disseminating such information, but strong efforts should be made to

assign hard numbers to the predictions. In particular, communities must be given analytic

tools for estimating likely losses in the event of

a future earthquake, and credible means must

be developed to predict the likely benefits of

mitigation. At present, it is difficult to quantify

these basic parameters, and it is this absence

that perhaps most inhibits vigorous action at all

mitigation levels.26

 In addition to supplying such informational assistance to at-risk communities, the federal

government might wish to offer more direct

technical aid. This aid can take the form of supplied expertise (e.g., mitigation efforts in the

Salt Lake County of Utah were greatly enhanced by a three-year federal grant for hiring

an in-house county geologist—see box 4-2), or

through programs to assist in the education and

training of engineers and design professionals

in the principles of seismically resistant

construction.

 To complement activities on the seismic front,

efforts can be made to incorporate seismic implementation into a larger “all-hazards” framework. Much of the nonstructural preparation

required for seismic mitigation (e.g., predisaster emergency planning) is useful in the event

of fire, flood, wind storm, or other natural disasters, and can thus gain in political and eco26 The Federal Emergency Management Agency is currently supporting development of a computer-based tool to assist communities in

loss estimation, a promising endeavor that may considerably aid future implementation efforts.
Chapter 4 Implementation 123

For manv residents of the North Coast a large

financial Ioss will come if the doors of kitchen

cabinets are shaken open, throwing contents to

the floor. A few dollars spent now can prevent

most of that loss.

In choosing a latch, consider looks and ease of

use, The standard hook and eye(A) is an inexpensive and secure latch, but you may not close it

every time you enter the cabinet because it takes

extra effort to do so. A child-proof catch (E)

prevents a door from opening more than an inch or

two. These catches close automatically, but they

require an extra action every time you open the

door.

Some standard types of secure latches mount

on the surface of the door (B, C). Latches are

available that mount inside the door (D), hold the

door firmly shut and open by being pushed gently

inward. These are marketed under names such as

push latch, touch latch, or pressure catch. If you

cannot find these latches, ask your hardware dealer

to order them for you.

Protect Your Belongings

Falling objects and toppling furniture can be dangerous and expensive to replace or repair.

● Move heavy items, such as pictures, mirrors or tall

dressers, away from your bed.

● Secure tall furniture and bookcases with lag bolts to wall

studs. Add lips to shelves to prevent costly items from

sliding off. Be sure adjustable shelves cannot slide off their

supports.

● Put latches on cabinet doors, especially at home in your

kitchen and at work or school laboratories

● Fasten heavy or precious items to shelves or tables.

Secure file cabinets, computers, televisions and machinery that may overturn during an earthquake.

● Store potentially hazardous materials such as cleaners,

fertilizers, chemicals, and petroleum products in appropriate containers and in sturdy cabinets fastened to the wall

or floor.

● In your office, be sure heavy objects are fastened to

the building structure and not just to a movable wall. Ask

a carpenter or an electrician to determine whether light

fixtures and modular ceiling systems are securely fastened.

● Be sure your water heater is fastened to the wall studs

and that all gas heaters and appliances are connected

to the gas pipe through flexible tubing. If you use propane gas, be sure the storage tank is secured against

overturning and sliding.

● Secure your wood stove to wall or floor studs. Make

sure you have a fire extinguisher close at hand.

● Check with your school officials to be sure they have

taken similar precautions.

Outreach and education materials, such as this pamphlet on safeguarding household effects, can both foster and guide

mitigation efforts.
124 | Reducing Earthquake Losses

nomic attractiveness when viewed in a larger

context.

 Lastly, consideration can be given to making

NEHRP less of a purely voluntary, information-driven program by attaching strong incentives for action and regulatory or economic

penalties to inaction (e.g., through changes in

federal disaster relief or insurance). These options, which are discussed in chapter 1, can also

act as a tool for enforcement (e.g., by using premortgage inspections to ensure building code

compliance).

All of the above efforts require insight into the

many political, economic, social, and practical

forces that shape the implementation process. It

should be reemphasized that the current understanding of these forces is by no means complete.

Social science research into the behavior of communities and individuals is thus of considerable

importance—all the more so if substantial

changes to current policy are being considered

(e.g., the possible use of mandatory earthquake insurance to foster seismic mitigation). Ongoing

NEHRP-funded social science research has already illuminated many of the factors affecting

implementation within the current NEHRP

framework; this effort might profitably be

strengthened or extended. In particular, substantial social science knowledge gaps remain that

hinder efforts to improve NEHRP. Chief among

these are the following:

 How might individuals respond to financial incentives (such as insurance) for implementation?

 Does the current de facto insurance framework

(federal disaster assistance) inhibit state, local,

and private implementation efforts, and if so, to

what extent?

 Where do the true bottlenecks occur in the enforcement process for seismic building codes

(e.g., to what extent does the trouble lie in onsite building inspection, in plan checking at the

design stage, or in unexpected variability in

construction practices and standards)?

 Will different parts of the country respond differently to proposed implementation strategies, and if so, what regional variations are to

be expected?

Successful research into these matters will greatly

improve action within the current implementation

framework, and will be critical to any efforts at extending program scope.
Appendix A:

The National

Earthquake Hazards

 Reduction Program

he 1964 Alaska and 1971 San Fernando,

California, earthquakes increased public

awareness of U.S earthquake risks and led

to numerous task forces, reports, and proposals for establishing a federal earthquake program. Then, in the mid-1970s, a number of events

led to the growing momentum for federal legislation:

 China successfully predicted a major earthquake before it occurred, saving at least tens of

thousands of lives.

 China and Guatemala suffered large and damaging earthquakes.

 The “Palmdale” bulge, a section of the San Andreas fault showing uplift, was identified.

 Various expert panels and committees released

reports on earthquakes, some of which stated or

implied that the United States was behind China, Japan, and Russia in its commitment to and

understanding of earthquake prediction.

 There was considerable optimism in the scientific community that earthquake prediction was

feasible. For example, a National Academy of

Sciences report recommended that the United

States make a national commitment to a longterm earthquake prediction program.1

 The President’s Commission on Science and

Technology put together a panel that produced

a report (commonly known as the NewmarkStever report) laying out a preliminary plan and

budget for a federal earthquake program.

EARTHQUAKE HAZARDS

REDUCTION ACT

Various bills to establish a federal earthquake program were introduced in Congress in the early and

mid-1970s. However, none were enacted until

1977, when the Earthquake Hazards Reduction

Act2 was passed. Several aspects of the original

legislation are worthy of note. First, it was developed and enacted in an era of great optimism about

the potential for earthquake prediction—that is,

accurate short-term forecasts of the location, magnitude, and timing of earthquakes. The legislation

reflects this, for example, stating:

1 National Research Council, Predicting Earthquakes: A Scientific and Technical Evaluation—with Implications for Society (Washington,

DC: National Academy of Sciences, 1976), p. 3.

2 Public Law 95-124, Oct. 7, 1977.

| 125
126 | Reducing Earthquake Losses

A well-funded seismological research program in earthquake prediction could provide

data adequate for the design of an operational

system that could predict accurately the time,

place, magnitude, and physical effects of

earthquakes.3

Second, although the bill listed a number of

nonresearch objectives, including public education and code development, much of the original

legislation was directed toward research. For example, the bill authorized agency appropriations

only for the U.S. Geological Survey (USGS) and

the National Science Foundation (NSF), to conduct or fund earthquake-related research. Third,

the legislation did not make clear how the nonresearch objectives were to be implemented.

Instead, responsibility for implementation was

given to the President, who was charged with developing an implementation plan. Thus, the program began with immediate activity by two

relatively strong research organizations, USGS

and NSF, but without a clearly defined implementation component and without a lead agency.

The President’s implementation plan,4 sent to

Congress in 1978, gave much of the responsibility

for implementation to a “lead agency,” although

just which agency was not specified. Other federal

agencies were given specific tasks, including participation in a multiagency task force that was to

develop design standards for federal projects.

Executive Order 12148, dated July 20, 1979, designated the then newly created Federal Emergency Management Agency (FEMA) as the lead

agency.5

REAUTHORIZATION HISTORY

The National Earthquake Hazards Reduction Program (NEHRP) has been reauthorized eight times

since its inception (see table A-1); however, only

two of these reauthorizations made significant

changes to the program. The 1980 reauthorization6 established FEMA as the lead agency, and

extended NEHRP authorizations to FEMA and to

the National Bureau of Standards (now the National Institute of Standards and Technology,

NIST).

The 1990 reauthorization (Public Law

101-614) made several substantial changes. The

Senate report accompanying the final bill noted

several congressional concerns with NEHRP, including,

. . . the slow and, in the view of many experts,

inadequate application of research findings to

earthquake preparedness; . . . the need to improve coordination of the agencies in the program and define better their roles; . . . the need

to update and broaden the scope of the

[NEHRP].7

In response to these and other concerns, the following major changes were made:

 references to earthquake prediction and control

were downplayed;

 program objectives were clarified and expanded, for example, education, lifeline research,

earthquake insurance, and land-use policy;

 the role of FEMA as lead agency was clarified

and defined, for example, program budgets,

written program plans, reports to Congress, a

3 Ibid., sec. 2(4).

4 Executive Office of the President, “The National Earthquake Hazards Reduction Program,” June 22, 1978.

5 U.S. Congress, General Accounting Office, “Stronger Direction Needed for the National Earthquake Program,” GAO/RCED-83-103,

July 26, 1983, p. 2.

6 Public Law 96-472, Oct. 19, 1980.

7 U.S. Congress, Senate Committee on Commerce, Science, and Transportation, NEHRP Reauthorization Act, Report 101-446 (Washington, DC: Aug. 30, 1990), p. 3.
Appendix A The National Earthquake Hazards Reduction Program 1127

Provided

Public Law Date of reauthorization

number passage for fiscal years Significant changes or additions

95-124

96-472

97-80

97-464

98-241

99-105

100-252

101-614

103-374

Oct. 7, 1977

Oct. 19, 1980

NO V . 20, 1981

Jan. 12, 1983

Feb. 22, 1984

Sept. 30, 1985

Feb. 29, 1988

NOV 16, 1990

Oct. 20, 1994

1978, 1979, 1980

1981

1982

1983

1984, 1985

1986, 1987

1988, 1989, 1990

1991, 1992, 1993

1994, 1995, 1996

—

SOURCE Off Ice of Technology Assessment, 1995

comprehensive education program, and grants

to states;

the roles of USGS, NSF, and NIST were clarified (but not altered significantly); and

the President was required to ensure that federal

agencies issue seismic safety regulations for

new buildings, and adopt seismic standards for

existing federal buildings lacking adequate

seismic resistance.

The 1994 reauthorization made no substantive

changes in NEHRP, however the hearings and language in the report accompanying HR 3485 out of

the House Committee on Science, Space, and

Defined and initiated program.

Authorized funds for U.S. Geological Survey and National Science Foundation only.

Directed President to select lead agency for implementation.

Defined Federal Emergency Management Agency (FEMA) as

lead agency.

Authorized funds for FEMA and National Bureau of Standards

(now National Institute of Standards and Technology).

None.

None.

None.

None.

None.

Eliminated some references to prediction consequences and

to earthquake control.

Clarified objectives of National Earthquake Hazards Reduction

Program, emphasizing implementation.

Required seismic regulations for new federal buildings, and

the adoption of seismic regulations for existing federal buildings.

Clarified agency roles.

None.

Technology (now the Committee on Science) provide some insight into congressional views of and

concerns with NEHRP. The report stated:

The [House Science, Space, and Technology] Committee is concerned about the effectiveness of the NEHRP. Recent hearings have raised

long-standing concerns about NEHRP—lack of

an overall strategic plan; insufficient coordination among the agencies to shape a unified, coherent program; insufficient application of

results of NEHRP research to limit losses; and

inadequate emphasis on research to mitigate

earthquake damage.8

8 

U.S. Congress, House Committee on Science, Space, and Technology, “Earthquake Hazards Reduction Act Reauthorization,” Report

103-360, NOV. 15, 1993, p. 6.
128 I Reducing Earthquake Losses

Fiscal year

SOURCE: Office of Technology Assessment, 1995

The Committee took two steps to address these

concerns: first, members of the House of Representatives sent a letter to the President requesting

an executive branch review of NEHRP. The

executive branch review was given to the White

House Office of Science and Technology Policy,

which as of August 1995 had not yet issued their

findings. Second, the Committee sent a letter to

the director of the congressional Office of

Technology Assessment (OTA) requesting that

OTA “review Federal efforts to reduce earthquake

damage.” This report is OTA’s response to that

request.

BUDGET

As for all federal programs, the budget process for

NEHRP involves two separate congressional

processes, authorizations, and appropriations.

NEHRP’s authorizations give permission to the

agencies to spend up to the amount authorized for

the activities discussed in the legislation. The appropriations process, however, provides the actual

funding to do the work. For NEHRP, as for almost

all government programs, authorizations and appropriations are under separate committees of

Congress. As NEHRP is a relatively small component of the agency budget, the congressional appropriations committees generally do not directly

specify the amount of money to be spent on

NEHRP activities. Instead, each agency determines its own budget priorities in conjunction

with the Office of Management and Budget, and

submits this budget (which specifies NEHRP

spending levels) in the President’s annual budget

request. The appropriations committee, in turn, either accepts this overall budget level or sets it at a

different level.

In the past, NEHRP authorizations have usually exceeded the actual spending (see figure A- 1 ).

Actual spending has increased in current dollars,

but has decreased overall in constant dollars (see

figure A-2).

Current dollars

1978 80 82 84 86 88 90 92 94

Fiscal year

SOURCE Off Ice of Technology Assessment, 1995
Appendix B:

Agency Efforts

 in the Current

 NEHRP

our agencies—the National Science

Foundation (NSF), the U.S. Geological

Survey (USGS), the Federal Emergency

Management Agency (FEMA), and the

National Institute of Standards and Technology

(NIST)—have specific responsibilities within the

National Earthquake Hazards Reduction Program

(NEHRP). Figure B-1 shows the division of

NEHRP funding among the principal agencies.

This appendix describes each agency’s current

NEHRP efforts and outlines earthquake-related

activities by other federal agencies that are outside

the formal NEHRP framework.

U.S. GEOLOGICAL SURVEY

USGS receives the largest share of NEHRP

funds—about $50 million in FY 1994, accounting

for more than half of all NEHRP spending. In recent years, USGS has used its NEHRP funds to

pursue four goals:

 understanding what happens at the earthquake

source,

 determining the potential for future earthquakes,

 predicting the effects of earthquakes, and

 developing applications for research results.1

Supporting efforts span a wide range of activities, from research into basic earthquake processes to mapping expected ground motions for use

in building design codes. More than two-thirds of

NEHRP funding is used internally—to support

USGS scientists in regional programs, laboratory

and field activities, national hazards assessment

projects, and seismic network operation. The remainder is spent as grants to outside researchers

for specific projects. In general, the internal work

focuses on applying knowledge to describe hazards, while the external program emphasizes expanding and strengthening the base of scientific

knowledge.

Three specific aspects of U.S. Geological Survey’s NEHRP-related work are discussed below:

the geographic focus of the work, efforts made at

1 Robert A. Page et al., Goals, Opportunities, and Priorities for the USGS Earthquake Hazards Reduction Program, U.S. Geological Survey Circular 1079 (Washington, DC: US Government Printing Office, 1992), pp. 1-2.

| 129
130 I Reducing Earthquake Losses

FEMA

20.8%

KEY: FEMA = Federal Emergency Management Agency; NIST = National Institute of Standards and Technology; NSF = National Science

Foundation; USGS = U.S. Geological Survey.

SOURCE: Office of Technology Assessment, 1995, based on NEHRP

budget data.

improving technology transfer, and the postearthquake investigation program.

■ Geographic Focus

Concentrated for years primarily in California,

USGS research and hazard assessment activities

expanded in the mid- 1980s to include a multiyear

effort to fully characterize seismic hazards along

the Wasatch fault zone in Utah. Beginning in

1991, USGS divided a substantial portion of its resources among four regions where the earthquake

hazard is most severe: southern California, northern California, the Pacific Northwest, and the central United States2 (see table B-l). A regional

coordinator is responsible for coordinating all aspects of the program with state and local agencies,

engineering groups, county emergency managers,

and planners. 3 Although California still receives

the bulk of the funding set aside for regional studies, USGS has shifted toward a more national program. The most noticeable remaining gap in

coverage is metropolitan areas in the Northeast

that have significant seismic risk (e.g., Boston and

New York City).

■ Technology Transfer

USGS has several programs intended to promote

the use of agency-produced knowledge and tools.

Examples include the following:

USGS works with the California Division of

Mines and Geology (a state agency) to develop

geographical information systems for use in

studying high seismic risk regions of the state.

USGS supports the Southern California Earthquake Center (SCEC). SCEC is a multidisciplinary effort to catalog and quantify regional

earthquake hazards and to transfer this information to the mitigation community. It is described further under NSF activities.

With FEMA, USGS has assisted in establishing the Coordinating Organization for Northern California Earthquake Research and

Technology (CONCERT). With members from

government agencies and private sector organizations, CONCERT provides a framework

for members to exchange ideas and hold public

workshops. Their objective is more effective

transfer of new technologies and research results to the region’s engineering community.

USGS encourages the exchange of ideas and

expertise between “sister cities” with similar

seismic risks. One of the first such exchanges

2 The Pacific Northwest refers to northernmost California, Oregon, Washington, and Alaska; the central United States include Indiana,

Illinois, Missouri, Kentucky, Tennessee, Arkansas, and Mississippi. Craig Weaver, Acting USGS NEHRP Coordinator, personal communication, May 9, 1995.

3 Along with three discipline coordinators (who oversee geographically based studies outside the four primary regions, laboratory and

theoretical studies, and the national seismic network system), the four regional coordinators oversee peer review panels that advise USGS on

funding priorities. Ibid.
●

Appendix B Agency Efforts in the Current NEHRP 131

Program element FY 1995 spending (million dollars)

Internal External Total

Northern California

Southern California

Pacific Northwest

Central United States

National and international

Seismic networks

Earthquake process and theory

Southern California Earthquake Center

Other

Total

7,096.7

5,385.2

2,434.2

1,853.6

2,772.1

5,040.0

2,491.3

7,870.0

34,943.1

1,830.0

1,900,0

1,316,1

1,000.5

1,067.2

2,620.0

919.8

1,200.0

2,118.4

13,972.0

8,926.7

7,285.2

3,750.3

2,854.1

3,839.3

7,660.0

3,411.1

1,200.0

9,988.4

48,915.1

NOTE Other includes miscellaneous administration and program assessments.

SOURCE: Office of Technology Assessment, 1995, based on detailed U.S. Geological Survey budget data

involved hazard planners and engineers from

Watsonville, California, and their counterparts

in Anchorage, Alaska. Other sister-city meetings are planned.

USGS operates the National Earthquake Information Center (NEIC) in Golden, Colorado.

NEIC has three main missions: 1) to determine,

as accurately and rapidly as possible, the location and magnitude of damaging earthquakes;

2) to collect and distribute seismic data for use

in research; and 3) to pursue research into locating and understanding earthquakes. In support

of these missions, NEIC distributes a number

of products (see table B-2).

USGS makes earth science data and maps

available over the Internet. For example, data

centers in northern and southern California provide maps of recent regional earthquakes, the

location of and data from geodetic and seismic

monitoring stations, and links to other Internet

sites with related data or topics. Other information is becoming increasingly available for use

by researchers, educators, and the public.

Future Directions

NEHRP achievements in recent years include increased awareness on the part of state and local officials, engineering associations, and other private

sector organizations of earthquake hazards and

risks. According to USGS, these groups have become more sophisticated as to what they need next

from NEHRP. To better serve their needs, USGS

has redesigned the major elements of its FY 1996

NEHRP effort as follows:

assessing national and regional earthquake hazard and risk,

assessing major urban area earthquake hazard

and risk,

understanding earthquake processes,

providing national real-time earthquake hazard

and risk assessment, and

providing national geologic hazards information services.4

4 Ibid.
132 I Reducing Earthquake Losses

Title Description

Quick Epicenter Determinations Very preliminary list of significant quakes, compiled daily and available for

computer access by telephone line.

Preliminary Determination of Epicenters Initial locations prepared and distributed weekly to those contributing data

to the NEIC; also published in a monthly listing available via the Superintendent of Documents in Washington, DC.

Earthquake Data Report Monthly publication that provides additional, more detailed Information for

seismologists on a data exchange basis.

Other products CD-ROMs, maps, and an annual book of U.S. earthquakes.

SOURCE U S Geological Survey, National Earthquake Information Center, 1994 Guide to Products and Services (Golden, CO 1994)

❚ Post-Earthquake Investigations

The 1990 NEHRP reauthorization5 directed

USGS to establish a post-earthquake investigation program, to study and learn lessons from major earthquakes. USGS has supported post-quake

work for both U.S. and non-U. S., major earthquakes. This work has allowed USGS to collect

perishable data on aftershocks and earthquake-induced damage.

After the Northridge earthquake in 1994, Congress passed a supplemental appropriations bill

that, in part, funded USGS to install a seismic

monitoring system that can better measure strong

ground motions. This system will improve the

ability to provide real-time information on earthquake size, location, and likely effects.

NATIONAL SCIENCE FOUNDATION

NSF receives about one-quarter of the NEHRP

funding. Its NEHRP spending is in two distinct

areas: fundamental earth science, and engineering

and social science research. The earth science research, overseen by the Earth Sciences Division in

the Directorate for Geosciences, accounts for 11.4

percent of NEHRP funds in FY 1994. The engineering and social science research in the Earthquake Hazard Mitigation Program within the

Directorate for Engineering accounts for 15.6 percent of NEHRP funds. Figure B-2 provides funding trends in current dollars for both areas.

❚ Earth Science Research

NSF uses NEHRP resources to support earthquake-related earth science research through two

main channels: direct grants to researchers and

support for various university consortia, including the Incorporated Research Institutions for

Seismology (IRIS) and the Southern California

Earthquake Center (see table B-3). In addition, using non-NEHRP funds, NSF supports the University Navstar Consortium (UNAVCO) that

provides technical assistance and equipment to investigators for geodetic studies and other earth

science research.

Direct Grants

NSF awards research grants directly to investigators for the study of earthquake sources, active tectonics, earthquake dating and paleoseismology,

and shallow crustal seismicity. 6 For FY 1990 to

1994, instrument-based seismology, geodesy, and

other tectonics received the bulk of the awards (on

5 Public Law 101-614, NOV. 16, 1990.

6 James Whitcomb, Director, Geophysics Program, National Science Foundation, personal communication, Nov. 21, 1994.
Appendix B Agency Efforts in the Current NEHRP | 133

Fiscal year

SOURCE Office of Technology Assessment, 1995, based on National Science Foundation budget data

the order of 90 percent); paleoseismology and microzonation efforts, in contrast, comprised about 5

percent of the overall budget for direct grants (see

table B-4).

Incorporated Research Institutions

for Seismology

IRIS is a university-based consortium that supports research in seismology by providing facilities for instrumentation and for data collection,

archiving, and distribution. IRIS is supported by

NSF (in part with NEHRP funds) and by the Air

Force Office of Scientific Research.

IRIS, in partnership with USGS, is building a

multiuse global network of modem, digital seismograph stations. According to IRIS, the Global

Seismographic Network supports NEHRP by enabling detailed assessments of the frequency of

earthquakes around the world and of their anticipated ground motions. In 1994, 20 new stations

were added to the network, bringing the total to

72. 7

Through PASSCAL (Program for Array Seismic Studies of the Continental Lithosphere), IRIS

provides portable instrumentation and support facilities for the study of seismic sources and earth

structure. Under development is the Rapid Array

Mobilization Program, intended to support rapid

deployment of instruments in the field immediately after a large earthquake or volcanic event.8

Another significant function of IRIS is the Data

Management System, which tracks the operation

of the stations and archives the data. In addition,

the IRIS Data Management Center (in Seattle,

Washington) makes available via the Internet

these data, customized data products, and a number of other historical data sets.

7 Incorporated Research Institutions for Seismology, 1994 Annual Report (Arlington, VA: 1994), p. 5.

8 Incorporated Research Institutions for Seismology, 1992 Annual Report (Arlington, VA: 1992), p. 18.
134 I Reducing Earthquake Losses

Spending

Element (million dollars)

Direct grants $4,3

incorporated Research Institutions for Seismology 3.6

Southern California Earthquake Center 3.3

Total $11.2

SOURCE: Office of Technology Assessment, 1995, based on detailed National Science Foundation budget data

Award totals Percentage of

Research area (thousand dollars) overall awards

Seismology

Tectonics

Geodesy

Nongeodetic

Paleoseismology

Microzonation

Tsunami

Other

Total NSF grants

$10,450

3,763

4,966

711

383

305

1,077

$21,655

48.3

17.4

22.9

3.3

1.8

1.4

5.0

100,0

NOTES: Other includes support for workshops, travel, and conferences. The total does not include staff salary and expenses.

SOURCE. Off Ice of Technology Assessment, based on 1994 National Science Foundation geosciences award data

Southern California Earthquake Center

SCEC serves as the focal point for regional studies

of earthquake hazards and risk mitigation measures. The principal institutions involved are:

University of Southern California; University of

California-Los Angeles, San Diego, and Santa

Barbara; California Institute of Technology; and

Columbia University.

The center has a multidisciplinary outlook that

promotes earthquake hazard reduction by defining when and where damaging earthquakes will

occur in southern California, calculating expected

ground motions, and communicating this information to the practicing engineering community and the public. Products include conditional

probabilities for major faults, maps of seismotectonic source zones and regional probabilistic seismic hazards, assessments of the implications of

recent patterns of seismicity in the greater Los Angeles area, and up-to-date earthquake source databases.

SCEC also supports the operation of a seismic

network and several data centers. In addition, the

center has facilitated installation of a comprehensive crustal strain monitoring network using the

Global Positioning System (GPS). This is intended to provide improved hazard estimation

from regional strain rates and increased understanding of post-quake deformation patterns.
Appendix B Agency Efforts in the Current NEHRP 135

Budget

Area (thousand dollars) Research examples

Geotechnical $2,621 Liquefaction, tsunamis.

Structural 2,722 Active controls, repair and rehabilitation.

Architectural and mechanical systems 2,719 Active controls, hazard evaluation.

Earthquake systems integration 2,567 Planning, social science.

Total $10,629

NOTE: Including the $4 million awarded to the National Earthquake Engineering Research Center (NCEER), the total FY 1994 National Science

Foundation engineering budget was $14.629 million.

SOURCE: Office of Technology Assessment, 1995, based on National Science Foundation detailed budget data.

Principal support comes from NSF (SCEC is

an NSF Science and Technology Center) and

USGS; SCEC is also supported by FEMA, the

California Department of Transportation, and the

City and County of Los Angeles.

University Navstar Consortium

UNAVCO maintains a standardized GPS equipment pool and data archiving center. One of the

primary applications of geodetic measurements to

earthquake research is the comparison of contemporary plate velocities and the rates of intraplate

and plate boundary zone deformation with geological and geophysical observations and models. 9 Space-based techniques have revolutionized

geodetic studies; they offer significant improvements over surface techniques in several applications.

❚ Earthquake Engineering

The NSF earthquake engineering budget for FY

1994 was $14.6 million. It includes $4 million for

the National Center for Earthquake Engineering

Research (NCEER); the remainder is divided

among four major research areas (see table B-5).

National Center for Earthquake

Engineering Research

NCEER, located in Buffalo, New York, was established in 1986 with a five-year, $25-million grant

from NSF.10 This grant was renewed in May 1991

for five more years and $21 million. Additional

funds for the center are provided by the State of

New York and by various institutions. ll The center mission is to “advance engineering, planning

and preparedness to minimize the damaging effects that earthquakes have.”12 As summarized in

9 University Navstar Consortium, FY 95-99 Proposal (Boulder, CO: n.d.), p. 7. Besides earthquake-related research, UNAVCO staff collaborate with the National Aerobatics and Space Administration, the National Center for Atmospheric Research, the National Oceanic and Atmospheric Administration, the Federal Aviation Administration, and university investigators in projects related to solid earth dynamics, climate,

and meteorology.

10The decision to award this grant to the State (University of New York at Buffalo, instead of to a competing bid from California researchers,

was a controversial one. The story of this battle is told in VSP Associates, Inc., “To Save Lives and Protect Property,” final report prepared for the

Federal Emergency Management Agency, Nov. 1, 1988, appendix C.

11 For example, the total NCEER budget in 1993-94 was $11.5 million: $4.0 million from NSF, $3.0 million from the Federal Highway

Administration for research into the seismic vulnerability of the national highway system, $2.0 million from the state of New York, and $2.5

million from other sources. National Center for Earthquake Engineering Research, Program Overview 1992-94 (Buffalo, NY: 1994), p. 30.

12 Ibid., p. 1.
136 I Reducing Earthquake Losses

Funding

Area (thousand dollars) Examples

Seismic hazard and ground motion $384 Ground motion and site response, seismic zonation.

Geotechnical engineering 375 Liquefaction and Iifelines,

Structures and systems 1,025 Retrofit methods, lifeline system analysis,

Risk and reliability 344 Development of risk-based design criteria,

Intelligent and protective systems 826 Base isolation, hybrid control systems,

Socioeconomic Issues 600 Insurance and mitigation relationships, estimating

damage with geographical Information systems,

hazard perception,

Implementation activities 446 Workshops, education and training.

SOURCE: Office of Technology Assessment, 1995, based on unpublished National Center for Earthquake Engineering Research (NCEER) budget

data

table B-6, the research portfolio supported by

NCEER ranges from geotechnical engineering to

socioeconomic issues. 13

Geotechnical

NSF-sponsored work on geotechnical engineering includes studies of liquefaction, tsunamis, the

response of soils to earthquakes, and the response

of structures to ground motion. This research is,

for the most part, applicable to all structures, including new and existing buildings and lifelines.

Structural

NSF-funded efforts in structures and earthquakes

include support of research in active and hybrid

control systems, design methodologies, seismic

behavior of components such as reinforced concrete frames or precast panels, and lifeline design.

A significant fraction of the research in this category is in the area of “structural control’’—the use

of active or hybrid intelligent control systems to

reduce seismic damage in structures.

Architectural anti Mechanical Systems

Much of the work in architectural and mechanical

systems looks at specific building components

such as composite walls and reinforced concrete

frames. As in the structural category, active or hybrid controls are a significant topic, accounting for

almost one-third of the funding in this category.14

Earthquake Systems Integration

Behavioral, social science, planning, and similar

research is funded in earthquake systems integration. Issues addressed include code enforcement,

decisions to demolish or repair a building, information transfer, and international comparisons

of mitigation.

13 For further information, see National Center for Earthquake Engineering Research, Research Accomplishments 1986-1994 (Buffalo, NY:

September 1994).

14 Research into structural control, active control, hybrid control, or similar phrases accounts for 32 percent of funding in the architectural

and mechanical areas. Source is NSF detailed budget data.
Appendix B Agency Efforts in the Current NEHRP | 137

FEDERAL EMERGENCY

MANAGEMENT AGENCY

FEMA has two distinct roles in NEHRP: 1) as lead

agency, FEMA is charged with overall coordination of the program; and 2) it also has responsibility for implementation of earthquake mitigation

measures.

❚ History

FEMA’s role in NEHRP can best be understood by

looking at how its role has evolved over time.

When NEHRP was founded in 1977, the legislation called for a lead agency but did not specify

what agency was to take that role. FEMA was given lead agency status by executive order in 1979.

This was confirmed by Congress in the NEHRP

reauthorization for 1981,15 which also provided

an explicit authorization for FEMA spending on

earthquakes.

In the early years of its NEHRP activities,

FEMA functioned primarily as a coordinator rather than as a strong leader or director. A 1983 U.S.

General Accounting Office (GAO) report criticized FEMA’s leadership, noting that FEMA had

not carried out several responsibilities assigned to

it in the legislation. GAO found that “FEMA

could better prepare the United States for a major

earthquake by more aggressively implementing

the [NEHRP] act’s requirements and providing

stronger guidance and direction to Federal agencies.”16 In 1987, an expert review committee, assembled to assist in NEHRP planning and review,

noted that “serious questions were raised regarding FEMA’s performance in its assigned role.”17

The committee recommended the creation of an

oversight commission, with some budget authority for NEHRP activities.

The 1990 NEHRP reauthorization contained

extensive reference to FEMA’s role in NEHRP.

Although there was not a clear change in FEMA’s

role, the legislation specifically directed FEMA

to:

 prepare an annual NEHRP budget for review by

the Office of Management and Budget,

 prepare a written NEHRP plan for Congress every three years,

 operate a program of state grants and technical

assistance, and

 ensure appropriate implementation of mitigation measures.

According to the Senate report accompanying the

legislation, the intent of this language was in part

to separate FEMA’s leadership function from its

operational (implementation) role.18

The 1993-94 reauthorization hearings suggest

that concerns over coordination and implementation continue. In the Senate hearings, a senator

asked of the witnesses, “Has coordination among

the four NEHRP agencies improved?”19 In the

House hearings, a representative asked, “Is the

program doing enough to ensure application of its

findings?”20

15 Public Law 96-472, Oct. 19, 1980.

16 U.S. General Accounting Office, “Stronger Direction Needed for the National Earthquake Program,” GAO/RCED-83-103, July 26,

1983, pp. i,ii.

17 Federal Emergency Management Agency, “Commentary and Recommendations of the Expert Review Committee 1987,” p. xiii.

18 U.S. Congress, Senate Committee on Commerce, Science, and Transportation, National Earthquake Hazards Reduction Program Reauthorization Act, Report 101-446 (Washington, DC: Aug. 30, 1990), p. 12.

19 U.S. Congress, Senate Committee on Commerce, Science, and Transportation, Subcommittee on Science, Space, and Technology, hearing, May 17, 1994, p. 4.

20 U.S. Congresss, House Committee on Science, Space, and Technology, Subcommittee on Science, hearing, Sept. 14, 1993, p. 2.
138 I Reducing Earthquake Losses

Approximate budget

Area (million dollars) Examples

Design and construction

standards 5.0

Leadership $1.3 User needs assessment.

Small-business outreach program.

NEHRP plans, reports, and coordination.

Manual for single-family building construction.

Preparation of seismic design values.

Preparation of NEHRP Provisions.

State and local hazards

reduction 6.1 Grants to states and cities for mitigation programs.

Grants to multistate consortia.

Education 1.1 Training in use of NEHRP Provisions.

Dissemination of information on retrofit techniques,

Multiple hazards 1.7 Loss estimation software development.

Wind-resistant design techniques,

Federal response planning 0.9 Urban search and rescue.

National federal response.

SOURCE: Federal Emergency Management Agency, Office of Earthquakes and Natural Hazards, “Funds Tracking Report,” Nov. 9, 1993,

❚ Current Activities

FEMA currently conducts a broad range of activities under its NEHRP mandate.21 Table B-7 lists

the FY 1993 budget and examples of activities for

each of six core areas of effort.

Leadership

According to the 1994 NEHRP report to Congress,

22 recent activities under FEMA’s leadership function include:

■ preparation of NEHRP plans and reports to

Congress,

■ assessment of user needs,

support of earthquake professional organizations,

arranging interagency meetings,

support of problem-focused studies—specific

issues of concern to the earthquake community,

and

outreach programs for small businesses.

Design and Construction Standards

FEMA contributes to the development of practices and standards to reduce seismic risk in both

new and existing structures. Examples include

sponsoring the development of the NEHRP Provi21 This section draws on Federal Emergency Management Agency, Building for the Future, NEHRP FY 1991-1992 Report to Congress

(Washington, DC: December 1992); Federal Emergency Management Agency, Preserving Resources through Earthquake Mitigation, NEHRP

FY 1993-1994 Report to Congress (Washington, DC: December 1994); and Federal Emergency Management Agency, Office of Earthquakes

and Natural Hazards, “Funds Tracking Report, FY 1993,” 1993,

22 Federal Emergency Management Agency, Preserving Resources through Earthquake Mitigation, see footnote 21.
Appendix B Agency Efforts in the Current NEHRP | 139

sions (a synthesis of design knowledge for adoption by model codes),23 development of

handbooks for retrofitting existing buildings, and

support of an earthquake testing and research facility at the University of Nevada.

State and Local Hazards Reduction Program

States and local governments bear primary responsibility for implementing plans and technologies to increase the resilience of communities

toward seismic hazards and thus minimize the

long-term effects of earthquakes. Through its

State and Local Hazards Reduction Program,

FEMA provides grants to states, local governments, and multistate consortia to support their

earthquake mitigation activities. Of the 43 states

and territories24 with low to very high degrees of

seismic hazard, 28 participate in one manner or

another in the FEMA program. Seventeen of these

states joined NEHRP at its inception in 1977.

Activities funded by FEMA grants vary, but

typically involve education, outreach, code adoption, training, and similar implementation activities. Indiana, for example, used FEMA funding to

develop a brochure on techniques to measure risk

in existing buildings, North Carolina used FEMA

funding to update its building code to include seismic provisions, and Arizona conducted public

awareness and education workshops.25

Financial Requirements

Current cost-sharing regulations are that FEMA

provides 100 percent of the first year’s funding;

25- and 35-percent in-kind matches are required

for years two and three; and a 50-percent cash

match from states is necessary for the following

years.26 The effects of the matching requirement

vary greatly among states. Participation by some

states appears to decline after reaching the 50-percent cash threshold; others have declined to participate at all because of the cash requirement.

For example, of the six states in the highest risk

category, only Wyoming does not formally participate in NEHRP. Wyoming indicated that fourthyear financial requirements (i.e., 50-percent cash

match) precluded such involvement. However, it

does participate in NEHRP-related activities and

belongs to the Western States Seismic Policy

Council.

Program Elements

The five primary matching fund program elements are: Leadership and Program Management;

Fundamental Research and Studies; Hazard Mapping, Risk Studies, and Loss Estimation; Hazard

Mitigation; Preparedness and Response/Recovery Planning; and Information and Education. In

addition, there is a “Special Projects and Other

Programs” category. Under the latter, for example,

New York State established in 1990 an Earthquake Lifelines Project to assess earthquake hazards, analyze lifeline vulnerability to support

mitigation efforts, inform and educate the public,

and provide training.

Typically, state efforts in the mitigation category relate to bridge safety analysis and reinforcement. New Jersey’s activities under this program,

however, also include a Prudent Business Practices program that encourages businesses to educate their employees and customers about seismic

risks. At least nine states have activities in all

NEHRP matching fund program areas.27

23 Building and Seismic Safety Council, NEHRP Recommended Provisions for the Development of Seismic Regulations for New Buildings,

1991 Ed., prepared for Federal Emergency Management Agency (Washington, DC: January 1992).

24 Including Guam, Puerto Rico, and the U.S. Virgin Islands.

25 Examples from Federal Emergency Management Agency, Building for the Future, see footnote 21.

26 VSP Associates, Inc., “State and Local Efforts To Reduce Earthquake Losses: Snapshots of Policies, Programs, and Funding,” report

prepared for the Office of Technology Assessment, Dec. 21, 1994.

27 Arkansas, California, Kentucky, Mississippi, Missouri, Nevada, New Jersey, New Mexico, and Tennessee.
140 | Reducing Earthquake Losses

Regional Efforts

Three regional organizations play important roles

in supporting individual states’ seismic safety efforts: the Western States Seismic Policy Council,

founded in 1977; the Central United States Earthquake Consortium (CUSEC), established in

1985; and, most recently, the Northeastern States

Earthquake Consortium. CUSEC is the only one

of the three groups that receives federal funds.

These groups typically facilitate the exchange of

information among states; provide a convenient

mechanism for holding meetings and training sessions; act as an “issue network” by helping to

forge state views on NEHRP priorities and programs; and, because of their administrative flexibility, can often do more things for their member

states than individual state procedures allow.28

Education

FEMA supports a number of educational activities, including a course on post-earthquake reconstruction, a natural hazards information center,

and dissemination of information on existing

building retrofits.

With funding from USGS and NSF as well as

FEMA, the Natural Hazards Research and Applications Information Center in Boulder, Colorado, serves as a national clearinghouse for

information on the economic loss, human suffering, and social disruption caused by earthquakes,

floods, hurricanes, tornadoes, and other natural

disasters.

Multi-Hazard Assessment and Mitigation

Some FEMA activities in NEHRP address multiple hazards. For example, FEMA recently supported work on wind-resistant designs for

buildings. Also under this heading is FEMA’s

support of the development of a loss estimation

computer tool for use by cities and states in earthquake planning.

Federal Response Planning

FEMA has primary responsibility for preparing

the federal government for national emergencies.

FEMA activities include carrying out exercises,

getting agencies to agree on emergency response

plans, and supporting regional operating centers.

FEMA has also supported urban search and rescue

teams.

NATIONAL INSTITUTE OF

STANDARDS AND TECHNOLOGY

NIST’s role in NEHRP has been largely in applied

engineering research and code development. The

agency’s funding under NEHRP has been low—

less than $500,000 annually until the 1990s—so

its NEHRP-related activities have been modest in

size and scope. Current NEHRP funding is

approximately $1.9 million.

❚ Funding History

The initial NEHRP legislation did not provide explicit authorization for NIST (then the National

Bureau of Standards), but NIST did receive some

funding in the early years of NEHRP. The 1980

NEHRP reauthorization bill specifically authorized NIST as one of the four key NEHRP agencies, and these authorizations have continued in

subsequent bills. In recent years, NIST’s budget

for earthquake-related activities has expanded due

to contributions from other federal agencies, as

well as a small contribution from the private sector. In FY 1994, for example, NIST received an

additional $1.5 million from the Northridge supplemental appropriations for a total NIST earthquake-related budget of nearly $3.6 million.29

28 Examples include securing out-of-state consulting assistance and paying honoraria and invitational travel so that speakers can participate in training conferences.

29 Richard N. Wright, Director, Building and Fire Research Laboratory, National Institute of Standards and Technology, testimony at hearings before the Senate Committee on Commerce, Science, and Transportation, May 17, 1994, table 1.
Appendix B Agency Efforts in the Current NEHRP | 141

❚ Activities

NEHRP’s initial legislation and subsequent

amendments did not define a specific role for

NIST. In the 1980s, NIST’s activities were “exclusively focused on the studies of performance of

buildings through in-house experimental and analytical research.”30 The 1990 NEHRP reauthorization defined NIST’s role as follows: “The

National Institute of Standards and Technology

shall be responsible for carrying out research and

development to improve building codes and standards and practices for structures and lifelines.”31

Increased funding since 1990 has allowed

NIST to expand into new areas. Its current

NEHRP-related work includes:32

1. Applied engineering research:

 preparation of guidelines for testing and

evaluation of seismic isolation systems,

 development of design provisions for precast

concrete connections and for seismic

strengthening of concrete frame buildings,

 testing of masonry walls to determine shear

capacity, and

 development of improved methods to predict the effects of ground motion on lifelines.

2. Code development and distribution, including

technical support for model code adoption of

the NEHRP Provisions.

3. Technology transfer (e.g., support of conferences and meetings for engineering research).

4. International cooperation, including technical

and financial support for various meetings and

exchange programs with other countries.

OTHER RELATED FEDERAL

AGENCY ACTIVITIES

Several federal agencies in addition to the four primary NEHRP agencies spend many millions of

dollars in earthquake mitigation. These efforts include evaluating the seismic safety of facilities

and improving their seismic resistance, conducting earthquake-related research and development,

and other efforts.33 Although detailed agency

spending data are not available, this non-NEHRP

federal spending on earthquake-related research

and development on upgrading the seismic resistance of facilities probably exceeds the $100 million spent annually by the four primary NEHRP

agencies.34 The contributions of many nonNEHRP agencies are summarized in table B-8.

30 Riley Chung, National Institute of Standards and Technology, personal communication, June 30, 1994.

31 Public Law 101-614, sec. 5b5, Nov. 16, 1990.

32 Federal Emergency Management Agency, Preserving Resources through Earthquake Mitigation, see footnote 21.

33 David W. Cheney, Congressional Research Service, “The National Earthquake Hazards Reduction Program,” 89-473SPR, Aug. 9, 1989.

34 The last budget data were for the period ending 1987. Ibid., p. 20.
142 I Reducing Earthquake Losses

Agency/department Examples

National Aerobatics and

Space Administration

(NASA)

National Oceanic and

Atmospheric Administration

(NOAA)

Department of Energy

(DOE)

Nuclear Regulatory

Commission (NRC)

Department of Defense

(DOD)

Department of Transportation (DOT)

Bureau of Reclamation,

Department of the Interior

Department of Veterans

Affairs (VA)

Department of Housing and

Urban Development (HUD)

Centers for Disease Control

and Prevention (CDC),

Department of Health and

Human Services

NASA conducts research and development (R&D) in basic earth processes. Its

space-based geodesy program has enabled important advances in monitoring and

characterizing crustal deformation and strain before, during, and after seismic events

NOAA provides real-time tsunami warnings for the United States and its possessions

and territories; the warnings are issued from two centers, located in Alaska and Hawaii. In addition, NOAA's seafloor mapping and monitoring of marine earthquakes

support improved understanding of offshore earthquake hazards and the reduction of

tsunami risk. NOAA also disseminates earthquake and tsunami data through the National Geophysical Data Center.

DOE has conducted earthquake hazard research related to nuclear powerplants and

waste disposal. DOE has upgraded the seismic resistance of many of its facilities,

including its national laboratories and nuclear weapons production facilities. As part

of its nuclear energy research programs, DOE has also studied ways to Improve the

seismic safety of new reactor designs.

In the past, NRC has sponsored seismographic networks in the eastern United States

to aid in analyzing seismic risks to nuclear powerplants. The commission has also

conducted engineering research related to improving the seismic resistance of nuclear powerplants and waste disposal facilities.

DOD has a seismic safety program to ensure appropriate seismic safety of its facilities, and conducts seismic R&D with applications to other government and privately

owned infrastructure. The Army Corps of Engineers, for example, addresses the seismic safety of dams. DOD also operates seismic stations for nuclear test monitoring

and supports seafloor research (by the Office of Naval Research).

DOT conducts seismic research in advanced earthquake-resistant design, construction, and retrofit of highway bridges through the American Association of State Highway and Transportation Officials specifications and guides of recommended practice,

assesses DOT facilities to prevent interruption of vital functions; and provides immediate response after major earthquakes.

The bureau is the lead technical agency for Interior’s Safety of Dams Program. In

addition to dam modifications, it conducts seismotectonic studies, operates three

seismic networks in Colorado and Wyoming, and operates strong-motion instruments

at dams and other critical facilities.

Since 1971, the VA has undertaken the seismic strengthening of its hospitals in areas

of moderate and high seismic hazard.

HUD funds earthquake studies related to disaster response, damage assessment,

and mitigation; conducts seismic risk assessments for HUD-assisted properties; develops seismic safety standards for such properties, as well as for manufactured

housing; and provides major rebuilding and emergency housing assistance to earthquake-stricken communities.

CDC conducts research on the health impact of natural and technological disasters in

order to develop strategies to prevent or reduce future disaster-related health problems.

SOURCES: Office of Technology Assessment, based on David W. Cheney, Congressional Research Service, “The National Earthquake Hazards Reduction Program, ” 89-473SPR, Aug. 9, 1989; and unpublished Office of Science and Technology Policy material, For a further description of earthquake programs in these and other contributing federal agencies, see Federal Emergency Management Agency, Preserving Resources Through

Earthquake Mitigation, FY 1993-94 NEHRP Report to Congress (Washington, DC: December 1994), pp. 131-170

4
Appendix C:

International

Earthquake

Programs

evastating earthquakes have been experienced all around the globe, at times with

astounding loss of life (see table C-1).

Figure C-1 illustrates recent world seismicity. Future occurrences of potentially damaging quakes are inevitable. As a result, many

countries have mounted extensive research and

development, hazard assessment, and disaster response programs related to earthquake hazards

and seismic risk.

A comprehensive discussion of the many international mitigation programs and their

achievements is beyond the scope of this report.

Instead, this appendix briefly describes efforts under way in a few countries whose seismicity and

mitigation practices may shed light on related

U.S. efforts. It also outlines the framework that

exists for cooperation and coordination among nations in understanding earthquake hazards and

mitigating seismic risk.

To summarize, both Japan and China have sizable earthquake research and mitigation programs. Unlike the United States, however, the

predominant focus of Japan’s efforts is seismic

monitoring and research applied toward predicting great earthquakes.

New Zealand also has a collection of efforts

similar in scope, if not scale, to the U.S. national

effort. One major difference is the inclusion of a

government-sponsored earthquake insurance program and a move toward mitigating economic disruption along with threats to life safety. Several

other countries have significant research programs or relevant data. For seismological or

paleoseismological data from intraplate earthquakes, China and Australia are sources.1 Russia,

China, and Japan have data on potential earthquake precursors; Japan also has strong-motion

data from subduction zone earthquakes and results from tsunami studies. In addition, Canada

and the United States exchange data and analyses

regarding seismic hazards in the west and east

(e.g., subduction zone quakes in the Pacific

Northwest and intraplate quakes in the northeastern United States).

1 Few earthquakes that occur in relatively stable regions of continents have surface expression. Of the 11 historic intraplate earthquakes that

have produced surface ruptures, five occurred in Australia since 1968. Michael Machette and Anthony Crone, “Geologic Investigations of Australian Earthquakes: Paleoseismicity and the Recurrence of Surface Faulting in the Stable Regions of Continents,” Earthquakes & Volcanoes,

vol. 24, No. 2, 1993, p. 74.

| 143
144 I Reducing Earthquake Losses

Location Year Magnitude Impact

Northern China

Lisbon, Portugal

San Francisco, California

Messina, Sicily

Tokyo, Japan

Assam, India

Chile

Alaska

Northern Peru

Guatemala

Tangshan, China

Northern Iran

Mexico City

Armenia

Loma Prieta, California

Northern Iran

Flores, Indonesia

Latur, India

Northridge, California

Kobe, Japan

Sakhalin Island, Russia

1556

1755

1906

1908

1923

1950

1960

1964

1970

1976

1976

1978

1985

1988

1989

1990

1992

1993

1994

1995

1995

—

—

8.3

7.5

8.3

8.4

Mw 9.5

Mw 9.2

7.7

7.5

7.9

7.7

8.1

6.8

7.1

7.7

7.5

Mw 6.2

6.8

6.8

Mw 7.0

800,000 killed

60,000 killed, fire

700 killed, fire

160,000 killed

140,000+ killed, fire

30,000 killed

5,700 killed, 58,000 homes destroyed, tsunami

131 killed, tsunami

67,000 reported killed

23,000 killed

240,000-650,000 killed

25,000 killed

10,000+ killed

55,000 killed

63 killed, $5 billion to $10 billion damage

40,000 killed

2,500 killed

9,750 deaths

57 killed, more than $20 billion damage

5,500+ killed, more than $200 billion losses

Approximately 2,000 killed

NOTE: A significant earthquake IS one that registers a magnitude of 6,5 or more, or one that causes considerable damage or loss of life On average,

60 significant earthquakes take place around the world each year. Mw representsmoment magnitude, a measure of the total seismic energy released

SOURCE: Office of Technology Assessment, based on Bernard Pipkin, Geology and the Environment (St Paul, MN: West Publishing Co , 1994), and

references cited therein; and William Ellsworth, U S Geological Survey, Menlo Park, personal communication, June 14, 1995

The United States is actively involved in sever- nation’s advances in earthquake mitigation, for

al cooperative programs established to share ex- example, in tsunami studies. 3

)

pertise and data. Joint research and technology

transfer projects have been especially useful to the AUSTRALIA

spread of seismic zonation practices around the Australia, a relatively stable continent far reworld. 2 (In a similar vein, technology transfer

from Japan to Chile has been integral to the latter

moved from the earth’s plate boundaries, received

2 Seismic zonation is the division of a geographic region into smaller areas or zones that are expected to experience the same relative severity of an earthquake hazard (e.g., ground shaking or failure, surface faulting, tsunami wave runup). Based on an integrated assessment of the

hazard, built, and policy environments, resulting zonation maps provide communities with a range of options for ensuring resilience to earthquakes and sustainable development. U.S. Geological Survey, Proceedings of the Fourth International Forum on Seismic Zonation, July 14,

1994, Chicago, IL, and Aug. 30, 1994, Vienna, Austria, Open File Report 94-424 (Reston, VA: n.d.), appendix B, p. 1.

3 See Maria Ofelia Moroni, “Technology Transfer on Earthquake Disaster Reduction Between Japan and Chile,” Bulletin of the International Institute of Seismology and Earthquake Engineering, vol. 27, 1993, pp. 199-211. In 1960, a tsunami that originated off the coast of Chile

caused nearly 1,000 deaths in that country and much destruction in Japan as well.
Appendix C International Earthquake Programs | 145

&30

3(30

60° 180° 60°

60°

SOURCE Office of Technology Assessment, 1995, adapted from F Press and R Siever, Earth, Second Edition (San Francisco, CA: W.H. Freeman

and Company, 1978), p. 412.

a wake-up call with respect to urban earthquake

hazards when a magnitude 5.6 (M5.6) earthquake

struck Newcastle in December 1989. It resulted in

about $2.86 billion (U. S.) in losses and 13

deaths. 4 The disaster led to increased studies of

the region’s intraplate quakes and a national program in seismic zonation.

The Australian Geological Survey Organization, in coordination with various state geological

surveys and universities, conducts the national

program in earthquake monitoring. With funding

from the federal agency Emergency Management

Australia and state governments, the Center for

Earthquake Research in Australia (CERA) has

completed seismic zonation maps for four of the

largest cities (Sydney, Newcastle, Melbourne, and

Brisbane and its environs). Maps for other urban

areas are in progresses

According to CERA, the outcomes of this mapping program have practical applications in many

areas, including seismic code formulation, emergency management, and community education.6

4 John M.W. Rynn, “The Potential TO Reduce Losses from Earthquakes in Australia, ” D.I. Smith and J.W. Handmer (cd.), Australia’s Role in

the International Decade for Natural Disaster Reduction, Resource and Environmental Studies No. 4, Journal of the Australian National University Center for Resource and Environmental Studies, 1991, p. 9.

5 For a description of initial efforts, see John M.W. Rynn, “Mitigation of the Earthquake Hazard Through Earthquake Zonation Mapping:

The Program for Urban Areas in Australia,” Proceedings of the Workshop Towards Natural Disaster Reduction, June 27-July 3, 1993, Okinawa,

Japan, S. Herath and T. Katayama (eds.) (Tokyo, Japan: International Center for Disaster-Mitigation Engineering, July 1994), pp. 115-136.

6 John Rynn, Center for Earthquake Research in Australia, personal communication, June 7, 1995.
146 Reducing Earthquake Losses

Organization Description Activities

Geological Survey of Canada

(GSC)

National Research Council

(NRC)

Canadian National Committee on Earthquake Engineering

Emergency Preparedness

Canada

Agency of the Ministry of Natural

Resources Canada

Established within the Ministry of

Industry, Science and Technology

Committee with representation from

GSC, NRC, and the private sector.

Agency within the Ministry of Defence

Seismic and strong-motion monitoring,

hazard estimation; international cooperation.

The agency’s Canadian Commission on

Building and Fire Codes promulgates the

National Building Code.

Develops seismic provisions for the National

Building Code, advises the Canadian Commission on Building and Fire Codes, and

provides advice to private industry on matters related to seismic hazard assessment

for specific projects.

Earthquake preparedness and response

planning.

SOURCE Off Ice of Technology Assessment, based on Peter Basham, Geological Survey of Canada, personal communication, Nov 24, 1994

Collaboration between Australia and other countries (e.g., neighboring developing nations in the

South Pacific, countries in Southeast Asia, and

South America, as well as the United States) is

rapidly increasing.

CANADA

Canada has experienced several large, damaging

earthquakes during its recorded history. Seismicity along its west coast is relatively well understood in terms of plate boundary convergence

offshore. The sources of intraplate earthquakes in

eastern Canada are less well known, but may be

related to compressional stresses acting on localized zones of weakness in the crust.7 Table C-2

shows the primary agencies and organizations

participating in Canada’s earthquake mitigation

effort. According to the Geological Survey of

Canada (GSC), it is the only federal agency concerned with seismological aspects of earthquake

loss reduction, and the only Canadian agency with

expertise in seismic hazard assessment.8

Canada’s primary earthquake-related research

goals are to: 1) understand the causes and effects

of earthquakes well enough to be able to assess

seismic hazards accurately throughout the country, and 2) improve knowledge of earthquake-resistant design and construction in order to provide

an adequate level of protection against future

earthquakes. Currently, a major research program

is underway to produce new zoning maps for trial

use, modification, and formal adoption in the year

2000 National Building Code of Canada. The existing code was adopted in 1985 and is based on

7 Dieter Weichert et al., “Seismic Hazard in Canada,” The Practice of Earthquake Hazard Assessment, International Association of

Seismology and Physics of the Earth Interior (Denver, CO: U.S. Geological Survey, 1993), p. 46.

8 Unless noted otherwise, the material in this section is drawn from Peter Basham, Acting Director, Geophysics Division, Geological Survey of Canada, personal communication, Nov. 24, 1994.
Appendix C International Earthquake Programs | 147

probabilistic analyses of peak acceleration and

peak velocity.9 According to GSC, relatively little

effort is devoted to microzonation, although some

efforts have been undertaken as university research projects.

CHINA

Strong intraplate earthquakes frequently occur

throughout China, which lies in the southeast part

of the Eurasian plate. The seismicity is thought to

be related to forces from the Pacific Plate to the

east and the Indian Ocean Plate to the southwest.

China’s historic earthquake record extends back

thousands of years; from 1831 B.C. to A.D. 1989,

17 great earthquakes, 126 major quakes, and almost 600 large earthquakes took place.10 Because

of their typically shallow depth and since relatively little building stock has been designed to resist

shaking, severe damage and casualties are likely

in the country’s densely populated areas from

large earthquakes (i.e., having magnitudes of 6

and higher).11

The Chinese government has a three-pronged

effort to address seismic risks. Earthquake prediction, resistance, and emergency relief responsibilities are accorded to the State Seismological

Bureau, the Ministry of Construction, and the

Ministry of Civil Affairs, respectively.12 A unified program is being assembled by the Chinese

Ten-Year Committee, in cooperation with United

Nations International Decade for Natural Disaster

Reduction13 (see table C-3.)

❚ Prediction

The large-scale development of an earthquake

prediction capability began after the 1966 Xingtai

earthquake (M7.2), which resulted in 8,000

deaths.14 Over the last couple of decades, a number of earthquake-monitoring systems have been

set up in China’s major seismic areas. The national

network consists of six regional telemetry networks, 12 local radio telemetry networks, and 10

digital seismographic stations.15 Data from these

monitoring systems, and from other observations,

support research in detecting precursors and correlating them with large earthquakes.

In 1975, hours before a M7.4 quake struck Haicheng, a series of foreshocks prompted residents

to construct earthquake huts (temporary shelters

adjacent to their homes) and local authorities to issue a warning of a major quake.16 Even with these

precautions, more than 1,000 people were killed.

Without these measures, a much larger percentage

of the 3 million people living in Haicheng might

have died inside collapsed buildings.17 However

the Chinese prediction system has predicted earthquakes that did not occur and has failed to predict

some that did. Several months after the Haicheng

9 With seven zones, the 1985 edition maps have a finer subdivision of zoning in moderate-risk areas and additional zones in the high-risk

areas relative to the previous edition (1970). P.W. Basham et al., “New Probabilistic Strong Seismic Ground Motion Maps of Canada,” Bulletin

of the Seismological Society of America, vol. 75, No. 2, April 1985, p. 563.

10 Xiu Jigang, “A Review of Seismic Monitoring and Earthquake Prediction in China,” Tectonophysics, vol. 209, 1992, p. 325. See chapter

2 for description of earthquake severity scales.

11 Ma Zongjin and Zhao Axing, “A Survey of Earthquake Hazards in China and Some Suggested Countermeasures for Disaster Reduction,” Earthquake Research in China, vol. 6, No. 2, 1992, p. 241.

12 Wang Guozhi, “The Function of the Chinese Government in the Mitigation of Earthquake Disasters,” Earthquake Research in China,

vol. 6, No. 2, 1992, p. 254.

13 Ibid.

14 Zongjin and Axing, see footnote 11, p. 243.

15 The six regions covered are Beijing, Shanghai, Chengdu, Shenyang, Kunming, and Lanzhou. Ibid.; and William Bakun, U.S. Geological

Survey, Menlo Park, personal communication, June 15, 1995.

16 Cinna Lomnitz, Fundamentals of Earthquake Prediction (New York, NY: John Wiley & Sons, Inc., 1994), pp. 24-26.

17 Bruce A. Bolt, Earthquakes (New York, NY: W.H. Freeman and Co., 1993), p. 194.
148 I Reducing Earthquake Losses

Organization Description Activities

Ministry of Construction Established in 1967, MOC is concerned

(MOC), Office of Earth- with emergency response, technical

quake Resistance codes and standards, development of

International cooperation, and education

and training in earthquake engineering.

State Seismological Bureau Established in 1971, the bureau is responsible for central management of

earthquake monitoring, prediction, and

scientific and engineering research.

National Natural Science Supports research in basic theory, techFoundation of China, De- nical advances, and earthquake hazard

partment of Architectural mitigation.

Environment and Structural

Engineering

Ministry of Energy, Science Established in 1989 by the China

and Technique Develop- Association of Power Enterprises in affilment Foundation of Power iation with the Ministry of Energy,

Industry

Funds proposals in earthquake resistance

research for buildings and engineering

structures; seismic response research for

special works, structures, and equipment;

strong-motion observation,

Plans and administers national seismological programs; conducts International cooperation and exchange programs in earthquake studies; performs field studies of

societal responses to earthquake hazards

and events.

The bureau’s Institute of Engineering Mechanics plays a key role in earthquake engineering research at the government level.

Funds projects in hazard assessment; soilstructure interaction; structural dynamic response; seismic resistance of lifelines; base

Isolation and structural control; and earthquake site investigation and aseismic experimental technology.

Awards grants to researchers and technological workers for studies related to hydroelectric, thermoelectric, and electric

systems.

SOURCE: U.S. Panel on the Evaluation of the U.S.-P.R.C. Earthquake Engineering Program, National Research Council Commission on Engineering

and Technical Systems, Workshop on Prospects for U.S.-P.R.C. Cooperation on Earthquake Engineering Research (Washington, DC: National Academy Press, 1993), pp. 8-10,

quake, a M7.8 quake struck Tangshan, apparently

without warning. Hundreds of thousands were

killed. 18

❚ Seismic Zonation and Building Codes

In 1957, China adopted its first earthquake intensity scale, a 12-level scale similar to the Modified

Mercalli Intensity scale, and initially focused its

mitigation efforts on buildings in the highest

hazard areas. In 1992, using data from recent

earthquakes and geophysical studies, China promulgated a new edition of its seismic intensity

zoning map. The Chinese zoning map reflects

both subjective measures of intensity and probabilistic analyses of ground motion expected from

future earthquakes. Grade 9 on the Chinese intensity scale is roughly equivalent to Zone 4 of the

1988 Uniform Building Code. 19

The first seismic code was promulgated in China in 1974.20 The Tangshan earthquake prompted

18 The Official estimate is approximately 250,000 deaths; however, unofficial estimates suggest that over 800,000 may have been killed.

19 The Unifom Building Code is one of three U.S. model codes on which state and local seismic codes are based. See chapter 3.

20 Hu Shiping, “Seismic Design of Buildings in China, ’’ Earthquake Spectra, vol. 9, No. 4, 1993, p. 704. The first draft, in 1957, was based

on the Soviet code.
Appendix C International Earthquake Programs 1149

SiX agencies participate in Japan’s earthquake prediction program. The Japan Meteorological Agency

(JMA) collects seismological data and oversees Japan’s prediction efforts. The Earthquake Assessment

Committee, consisting of six eminent seismologists, is responsible for analyzing potentially anomalous

data and reporting to the director of JMA a verdict of: 1 ) imminent danger, or 2) no danger. 1

The Geodetic Council of Japan acts as an advisory body to the Ministry of Education, Science and

Culture with respect to earthquake prediction, and oversees development of five-year program plans. Other agencies revolved in the prediction effort include the Maritime Safety Agency, the Geographical Survey

Institute, the Geological Survey of Japan, and the National Research Institute for the Earth Sciences and

Disaster Prevention (part of the Science and Technology Agency).2

Now in its sixth five-year plan, the program has both harsh critics, which include an increasing number

of Japanese scientists, and staunch defenders. Limited access to data, opportunity costs for other areas of

earthquake research, and the program’s narrow focus on the Tokyo region are among the motivations for

criticism.

1 Robert J. Geller, “Cash Falling Through the Cracks, ” The Daily Yomiuri, May 12, 1994, p. 6. The two options are designated black

and white verdicts, respectively. A gray verdict, or statement of intermediate probability, IS not permitted.

2 Robert J. Geller, “Shake-up for Earthquake Prediction, ” Nature, vol. 352, No. 6333, July 25, 1991, pp. 275-276

SOURCE Off Ice of Technology Assessment, 1995

— .

revision of this code; the effort was completed in Japan has a multipronged government program

1978. The present code, promulgated in January

1990, was revised from the 1978 version by the

China Academy of Building Research, along with

other professionals.2

1

JAPAN

The Eurasian, Philippine Sea, Pacific, and North

American Plates all converge in the vicinity of Japan. The relative movement of these plates causes

Japan to experience strong to great earthquakes

frequently, as well as face the threat of volcanic activity and tsunamis. The largest earthquakes have

originated in the subducted Philippine Sea and Pacific Plates, although the havoc wreaked on Kobe

by the 1995 Hyogoken-Nanbu earthquake reveals

the hazard posed by shallow crustal quakes to

densely populated cities.

to address its many seismic risks. Unlike the

United States, however, earthquake prediction is a

primary focus of Japan’s efforts to reduce losses

from earthquakes.

❚ Prediction

With spending on the order of $100 million per

year-a figure that does not include salaries-Japan’s prediction program receives funding comparable to the entire U.S. National Earthquake

Hazards Reduction Program (NEHRP). Initiated

in 1963, it is one of Japan’s largest and oldest research projects22 (see box C-l).

Pursuant to the 1978 Large-Scale Earthquake

Countermeasures Act, 10 regions have been designated for special monitoring. The Kanto-Tokai

Observation Network, for example, continuously

21 Ibid., p. 705.

22 Y. Ishihara, Office of Disaster Prevention Research, Japanese Science and Technology Agency, personal communication, June 16, 1995.
150 | Reducing Earthquake Losses

monitors crustal movements using more than 250

seismometers, strainmeters, and tiltmeters. In

addition, 167 Global Positioning System stations

operate in this area.23

The most recent five-year plan for the prediction program, adopted in 1993, continues intensive observation of the Tokai region, which is

expected to experience the effects of a great earthquake on the nearby Suruga Trough.24 Scientists

hope to detect the onset of the quake by monitoring seismicity, strain, and crustal deformation.

Previous major quakes on the Suruga and Nankai

Troughs were preceded by rapid crustal uplift.

❚ Building Codes and Engineering

Early in this century, Japan established one of the

first seismic design codes based on the performance of certain buildings in Tokyo during the

1923 Great Kanto earthquake.25 The years since

then have seen many advances in earthquake engineering research, seismic codes, and construction

practices, because of investment on the part of

both the government and the private sector.

The most recent code went into effect in

1981.26 The Japanese seismic design code differs

from the current U.S. guidance document for

building codes (i.e., the NEHRP Provisions27) in

that it calls for a two-stage design process. The

first phase follows an analysis approach similar to

that used in the NEHRP Provisions; it is intended

to preclude structural damage from frequent,

moderate quakes. The second phase is an explicit

assessment of the building’s ability to withstand

severe ground motions.28 Design forces used in

Japan also are typically significantly larger than in

the United States. As a result, Japanese buildings

tend to be stronger and stiffer than their U.S. counterparts, and will likely suffer less damage during

moderate or severe shaking.29

Japanese construction companies annually

spend a considerable amount on research and development, including testing of scaled building

models in large in-house laboratories and research

into passive and active control technologies. One

result is that new technologies for seismic protection have been incorporated into new buildings at

a faster rate than in the United States.30

The government’s engineering research facilities include a large-scale earthquake simulator operated by the National Research Institute for the

Earth Sciences and Disaster Prevention and used

by other agencies. Future evaluation of the seismic performance of the built environment will

likely be aided by the large set of strong-motion

data obtained from the Hyogoken-Nanbu quake in

January 1995; the data set includes near-fault re23 Ibid.

24 Dennis Normile, “Japan Holds Firm to Shaky Science,” Science, vol. 264, June 17, 1994, p. 1656.

25 The United States adopted its first code shortly thereafter, in 1927.

26 The Building Standard Law, proposed in 1977. For a description of Japan’s seismic design methods, see Andrew Whittaker et al., “Evolution of Seismic Design Practice in Japan and the United States,” The Great Hanshin Earthquake Disaster: What Worked and What Didn’t?

SEAONC Spring Seminar Series, Engineering Implications of Jan. 17, 1995, Hyogoken-Nanbu Earthquake, May 25, 1995 (San Francisco, CA:

Structural Engineers Association of Northern California, 1995), pp. 5, 10.

27 Building Seismic Safety Council, NEHRP Recommended Provisions for the Development of Seismic Regulations for New Buildings

(Washington, DC: 1991).

28 Whittaker et al., see footnote 26. Exemptions to this second phase of design are permitted only for buildings less than 31 meters in height

and having the requisite materials and configuration. Andrew S. Whittaker, Earthquake Engineering Research Center, University of California

at Berkeley, personal communication, May 29, 1995.

29 Whittaker, ibid.

30 David W. Cheney, Congressional Research Service, “The National Earthquake Hazards Reduction Program,” 89-473 SPR, Aug. 9, 1989,

p. 35.
Appendix C International Earthquake Programs | 151

cords that reflect rupture directivity and other effects encountered in the immediate vicinity of the

fault.31

❚ Response and Recovery

Within the National Land Agency, the Disaster

Prevention Bureau was established in 1984 to develop disaster countermeasures through coordination with various ministries and agencies. The

countermeasure framework has three primary

parts: 1) making cities more disaster resistant, 2)

strengthening disaster prevention systems (e.g.,

tsunami warning systems) and raising awareness,

and 3) promoting earthquake prediction. One related effort has been to set up the Disaster Prevention Radio Communications Network to link

agencies at the federal, prefectural, and municipal

levels.32

The primary responsibility for disaster response rests with local-level governments that

must ensure adequate water, food, and medical

supplies. As witnessed in the 1995 disaster, however, Kobe’s capabilities were overstretched, and

some argue that mechanisms for federal intervention were inadequate. Whether or to what degree

Japan’s earthquake research, mitigation, and response programs will change as a result of the

Kobe disaster is not yet clear. It must be noted that

the intensive monitoring programs intended to

support Japan’s prediction capability cover but a

small portion of the nation.

MEXICO

Off the western coast of Mexico, the North American Plate overrides the Cocos Plate. Historically,

the Cocos Plate is the most active in the Western

Hemisphere. This subduction zone has generated

almost 50 earthquakes greater than magnitude 7 in

this century, including the M8.1 quake that caused

extensive damage and loss of life in Mexico City

in 1985.33

Mexico currently has a national network of

nine broadband seismic instruments linked by satellite, plus a number of regional networks.34 Six

additional broadband stations will be installed in

1995, one of them through a cooperative project

with the U.S. Geological Survey.35 Since late

1987, the National University’s Geophysics Institute has operated a nine-station, short-period seismic network in the earthquake-prone state of

Guerrero.

To record and assess severe shaking, strongmotion instruments are located throughout the

Mexico City area. In cooperation with some U.S.

universities and the Japan International Cooperation Agency, arrays of digital strong-motion networks are also operated in Guerrero.

Seismic zonation maps (e.g., maps of maximum Modified Mercalli Intensity, and peak acceleration and velocity) have been incorporated into

the Mexican Building Code since the 1960s. In the

1985 quake, many high-rise buildings in an area of

the city underlain by a former lake bed collapsed

or were severely damaged. These buildings could

not withstand the resonance effects induced by the

long-period, long-duration shaking that occurred

on soft soils. Microzonation has since been completed in the portions of Mexico City most susceptible to seismic wave amplification and

liquefaction.36 Other cities (e.g., Acapulco and

31 Earthquake Engineering Research Institute, The Hyogo-Ken Nanbu Earthquake: January 17, 1995, preliminary reconnaissance report

(Oakland, CA: February 1995), p. 6.

32 Disaster Prevention Bureau, Earthquake Disaster Countermeasures Division, Earthquake Disaster Countermeasures in Japan (Tokyo,

Japan: National Land Agency, 1993), pp. 17-18.

33 Bernard W. Pipkin, Geology and the Environment (St. Paul, MN: West Publishing Co., 1994), pp. 83-35. The earthquake catalog of the

Geophysics Institute, National University of Mexico, contains 48 major quakes.

34 U.S.Geological Survey, see footnote 2, p. 31.

35 Ramón Zúñiga, Geophysics Institute, National University of Mexico, personal communication, June 12, 1995.

36 U.S. Geological Survey, see footnote 2.
152 | Reducing Earthquake Losses

Guadalajara) have recently been included in the

microzonation efforts. Based on recently collected data, new zonation maps are being prepared

for Mexico as an extension of the Canadianfunded Seismic Hazard in Latin America and the

Caribbean Project.37

NEW ZEALAND

New Zealand is located astride the boundary between the Australian and Pacific Plates; it is cut

and deformed by many active faults and folds.38

Not surprisingly, New Zealand has both an active

research program in earthquakes and a longstanding effort to improve the seismic resistance of its

built environment. In 1991, the nation adopted an

integrated approach to natural hazards management, of which earthquake mitigation is a major

part. Subject to certain constraints in the Resource

Management Act of 1991 and Building Act of

1991, regional and local authorities are responsible for controlling land use and construction for

the purpose of avoidance or mitigation of specific

hazards.39

❚ Research

The primary institutions conducting earthquakerelated research include the Institute of Geological

and Nuclear Sciences (IGNS), the Engineering

Schools of Auckland and Canterbury Universities, and the Institute of Geophysics at Victoria

University in Wellington. The latter has teaching

and research programs in seismology, including

seismic microzonation. Additional research is

conducted by earth science departments in other

universities and by some private civil engineering

consultants.40

IGNS has six programs, funded at $27 million

(U.S.) per year, which span the fields of geology,

seismology, and engineering seismology.41 For

example, IGNS is currently pursuing a research

program titled “Improvements to Earthquake Resistant Design” whose primary objectives are: improved modeling of strong ground motions;

enhanced models of the effects of large earthquakes on buildings, other structures, and the natural environment; and improved antiseismic

practices and technologies.42

The Earthquake Commission (EQC), which

provides earthquake insurance for domestic property and contents, also funds approximately

$340,000 (U.S.) of research per year. EQC, which

administers the Natural Disaster Fund on behalf of

the government, is the primary provider of natural

disaster insurance to residential property owners.

37 Zúñiga, see footnote 35. The Canadian International Development Research Agency funds the Seismic Hazard Project, now in its final

phase. The project has two major components: 1) establish a uniform catalog of earthquakes for Mexico, Central and South America, and the

Caribbean; and 2) develop probabilistic seismic hazard maps for this region. The Panamerican Institute of Geography and History, Organization of American States, oversees the multinational effort. James Tanner, Seismic Hazard in Latin America and the Caribbean Project, personal

communication, June 16, 1995.

38 Russ Van Dissen and Graeme McVerry, “Earthquake Hazard and Risk in New Zealand,” Proceedings of the Natural Hazards Management Workshop, Wellington, NZ, Nov. 8-9, 1994 (Lower Hutt, New Zealand: Institute of Geological and Nuclear Sciences Limited, 1994), p. 71.

39 See Christine Foster, “Developing Effective Policies and Plans for Natural Hazards Under the Resource Management Act,” in Proceedings of the Natural Hazards Management Workshop, see footnote 38, pp. 34-35. One result of the recent legislation is increased demand on the

part of regional and local authorities for seismic hazard and risk analyses.

40 Unless noted otherwise, this section is drawn from personal communications with Warwick D. Smith, Chief Seismologist, New Zealand

Institute of Geological and Nuclear Sciences, and John Taber, Institute of Geophysics, Victoria University of Wellington, Dec. 1, 1994.

41 The Ministry of Research, Science and Technology provides the New Zealand government with policy advice, including recommended

funding levels for different areas of research. Earthquake-related research is funded under the Earth Science and Construction categories, or

outputs. The Foundation for Research, Science and Technology allocates monies for research programs within each output.

42 A quarter of the program’s funding comes from industrial sources. Description of the IGNS Program, “Improvements to Earthquake

Resistant Design,” provided by Don McGregor, Chief Scientist, New Zealand Ministry of Research, Science and Technology, personal communication, Jan. 17, 1995.
Appendix C International Earthquake Programs | 153

As of 1996, however, owners of nonresidential

property will have to seek private coverage for

buildings and their contents.

Roughly 25 percent of New Zealand’s earthquake research is currently directed at microzonation. This work is included in both the Foundation

for Research, Science, and Technology and EQC

programs, and is also sponsored by regional and

local governments.

❚ Implementation

Under New Zealand’s Resource Management

Act, regional, district, and city councils are responsible for identifying and mitigating the effects of natural hazards. The councils exercise

their duties with respect to earthquake hazards

through zoning and microzoning, and by enforcing the New Zealand Building Code. This code is

written in performance terms and was published

in 1992, after preparation under the supervision of

the Building Industry Authority. There were previous seismic loading requirements in building

standards and other control documents dating

back to 1935. The code requires building owners

to maintain their buildings so that they continue to

meet the earthquake resistance requirements that

existed at the time the building was erected. In

some of the more earthquake-prone areas, territorial authorities have required upgrading of older

buildings to address possible seismic weaknesses

that can be recognized.43

The New Zealand National Society for Earthquake Engineering is a nongovernmental organization with approximately 600 members,

mostly civil engineers. The society plays a leading

role in communication among parties interested in

earthquake research, hazard and risk assessment,

and mitigation via engineering solutions. Likewise, the Building Research Association maintains close ties with building control officials and

manufacturers, who together expedite the introduction of research results into practice.44

Until recently, the main thrust of earthquake

mitigation efforts in New Zealand was preventing

building collapse and minimizing the hazard for

occupants. However, this risk was considered to

be less severe than for many other countries,45 and

today the reduction of economic disruption is receiving greater emphasis. Increasing the efficiency of restoration of infrastructure and lifelines is a

primary consideration.46

For example, local councils in Wellington and

later Christchurch established engineering exercises to coordinate efforts to sustain lifelines.

They focused on the interdependence of these lifelines in urban areas to assess ways in which weakness might be identified and mitigated.47

RUSSIA

Microzonation of the largest cities in Russia and

the former Soviet Union began in the 1950s, and

seismic zonation maps were incorporated into the

State Engineering Codes as early as 1957.48

Today, the primary institutions and organizations involved in Russia’s earthquake efforts are:

43 Gerald Rys, Assistant Chief Scientist, New Zealand Ministry of Research, Science and Technology, personal communication, July 4,

1995.

44 John Duncan, Research Director, Building Research Association of New Zealand, personal communication, Jan. 17, 1995.

45 Reasons include: 1) ongoing implementation of simple antiseismic measures based on early colonial experiences in severe earthquakes,

and 2) the fact that the majority of New Zealanders live in single-dwelling, typically wood-framed structures.

46 Smith and Taber, see footnote 40.

47 Interdependence relates to the effect of the outage of one utility service (e.g., power) on the time required by another service to recover.

The lifeline effort also designated critical areas—that is, where a number of lifelines are vulnerable in one location (e.g., a bridge carrying water,

gas, and power in addition to traffic). David Brundson, “Reducing Community Vulnerability to Earthquakes: The Value of Lifeline Studies,” in

Proceedings of the Natural Hazards Management Workshop, see footnote 38, p. 10.

48 U.S. Geological Survey, see footnote 2.
154 | Reducing Earthquake Losses

the Ministry of Russian Federation for Civil

Defense, Emergencies and Elimination of Consequences of Natural Hazards; the Interdepartmental Commission for Seismic Monitoring; and

the Russian Academy of Sciences. Russia operates several seismic and strong-motion monitoring stations. However, nearly all are still equipped

with analog instruments and transmission methods that limit the quantity and quality of data. The

number of stations in operation has decreased in

recent years due to lack of funding.49

In 1994, the Russian government approved the

establishment of a new program to develop a federal system of seismological networks and earthquake prediction, with several objectives:

 seismic hazard assessment,

 prediction of strong earthquakes based on comprehensive analysis of geophysical and geodetic precursors,

 epicentral seismological observations,

 strong-motion data for improvement of seismic

resistant design and construction,

 implementation of mitigation measures in

areas where strong earthquakes are expected in

order to evaluate their effectiveness, and

 development of methods for predicting humantriggered seismicity and for minimizing seismicity induced by mining or reservoirs.

The means to these ends include modernization of

observation stations, data transfer and storage

techniques, and improved coordination of the efforts of many ministries and agencies. As of late

1994, however, the government had not allocated

any financial resources to implement the program.50

VEHICLES FOR COOPERATION

AND COORDINATION

A number of organizations and other mechanisms

foster the international exchange of ideas and

practices in the area of earthquake research, mitigation, and response. For example, the U.S. Geological Survey (USGS) and the National Science

Foundation (NSF) maintain close working relationships with Japan in earthquake seismology.51

In addition, for many years, the United States and

Japan have held joint workshops under the auspices of the United States-Japan Panel on Wind

and Seismic Effects (see box C-2). The United

States has established and renewed scientific protocols with the People’s Republic of China, and

with Russia and other members of the Commonwealth of Independent States. Cooperation between the United States and Taiwan, and between

Latin American states, is ongoing, and there are

many such efforts with other countries.

Japan also has established cooperative exchanges with many countries, as have some other

nations (e.g., Canada and France). There are multilateral forums as well—notably the United Nations International Decade for Natural Disaster

Reduction (IDNDR), established in 1990 to promote mitigation and cooperation worldwide.52

Over the years, several regional programs have

49 According to one reviewer, the disastrous Sakhalin Island earthquake of May 1995 illustrates the decline of Russia’s earthquake program: the seismic monitoring network had been shut off, there was apparently no plan to retrofit the apartment buildings that collapsed, and the

emergency response effort suffered from a shortage of resources. William L. Ellsworth, U.S. Geological Survey, Menlo Park, personal communication, June 14, 1995.

50 Yu S. Osipov, President of the Russian Academy of Sciences, letter to V.F. Shumeiko, Chairman of the Federation Council of the Federal

Assembly of the Russian Federation, Nov. 1, 1994, in “The Shikotan Earthquake of October 4(5), 1994,” Russia’s Federal System of Seismological Networks and Earthquake Prediction, Information and Analytical Bulletin, Special Issue No. 1, November 1994.

51 Federal Emergency Management Agency et al., “National Earthquake Hazards Reduction Program: Five-Year Plan for 1992-1996,”

September 1991, p. 91.

52 The IDNDR sought, in part, to promote: the integration of hazard reduction policies and practices into the mainstream of community

activities; funding of additional research into the physical and social mechanisms of natural hazards and the disasters they precipitate; and elimination of constraints on the use of scientific and technical knowledge. National Research Council, The U.S. National Report to the IDNDR

World Conference on Natural Disaster Reduction, Yokohama, Japan, May 23-27, 1994 (Washington, DC: National Academy Press, 1994), p. 1.
Appendix C International Earthquake Programs 1155

The panel consists of 16 U.S. agencies, led by the National Institute of Standards and Technology, and

six Japanese agencies. Over the years, the panel has:

■

■

■

●

■

held 25 annual technical meetings for prompt exchange of research findings,

conducted more than 40 workshops and conferences on such topics as the repair and retrofit of structures,

conducted cooperative post-earthquake investigations in Japan and in the United States,

hosted visiting Japanese researchers and provided access for U.S. researchers to unique Japanese

facilities, and

organized cooperative research programs on steel, concrete, masonry, and precast concrete structures.

SOURCE. Richard Wright, Director, Building and Fire Research Laboratory, National Institute of Standards and Technology, testimony

at hearings before the Senate Committee on Commerce, Science, and Transportation, Subcommittee on Science, Technology, and

Space, May 17, 1994, p. 31

been established, including projects in the Balkans, countries adjacent to the Mediterranean Sea,

and central and South America.53

In general, there is extensive cooperation with

respect to the collection and sharing of earthquake

data. With the Global Seismographic Network

(GSN), earthquake source data are collected from

and distributed to Europe, Latin America, Asia,

and Australia.54 The Global Geodetic Network

uses high-resolution, space-based geodetic techniques to monitor crustal motion and deformation

around the world. It is supported by NSF, the National Aeronautics and Space Administration, and

the National Oceanic and Atmospheric Administration, and by agreements with some 45 countries

to exchange data and coordinate activities. 55

Post-earthquake investigations are another important means of collectively assessing the physical and societal impacts of damaging earthquakes

and spurring further progress in mitigating against

seismic risks. The Post Earthquake Evaluation

Program, initiated in 1992 by USGS, the United

Nations Educational, Scientific and Cultural Organization, and the Open Partial Agreement on

Major Hazards of the Council of Europe, has the

following objectives:

■

■

■

■

create a mechanism for sharing information,

strengthen interdisciplinary and interorganizational interfaces,

increase the worldwide capacity for post-earthquake investigations, and

foster the adoption of prevention, mitigation,

and preparedness measures.56

53 Participating and sponsoring organizations include USGS, the U.S. Agency for International Development, the United Nations Educational, Scientific and Cultural Organization, and national governments. U.S. Geological Survey, see footnote 2, p. 11.

54 Established by the Incorporated Research Institutions for Seismology (IRIS) and jointly operated with the USGS Albuquerque Seismological Laboratory, the University of California at San Diego’s International Deployment of Accelerometers group, and other member universities, the GSN is a rapidly expanding network of high-quality seismographs installed around the world for the purposes of earthquake and nuclear test monitoring and related research. In addition to data from the GSN, the IRIS Data Management Center has recently begun collecting

data from international seismic networks operated by the Federation of Digital Seismic Networks.

55 Office of Science and Technology Policy unpublished material.

56 

U.S. Geological Survey, see footnote 2, p. 42.
Appendix D:

Acronyms

Caltech California Institute of Technology

CDMG California Division of Mines and

Geology

CONCERT Coordinating Organization for

Northern California Earthquake

Research and Technology

CUBE Caltech-USGS Broadcast of Earthquakes

CUSEC Central United States Earthquake

Consortium

EWS Early Warning Systems

FEMA Federal Emergency Management

Agency

GIS Geographical Information System

GPS Global Positioning System

IRIS Incorporated Research Institutions

for Seismology

M magnitude

MMI Modified Mercalli Intensity

Mw moment magnitude

NCEER National Center for Earthquake

Engineering Research

NEHRP National Earthquake Hazards Reduction Program

NEIC National Earthquake Information

Center

NIST National Institute of Standards and

Technology

NSF National Science Foundation

NSN National Seismograph Network

PASSCAL Program for Array Seismic Studies

of the Continental Lithosphere

R&D research and development

REDI Rapid Earthquake Data Integration

SAR synthetic aperture radar

SCEC Southern California Earthquake

Center

UBC Uniform Building Code

UNAVCO University Navstar Consortium

URM unreinforced masonry

USGS U.S. Geological Survey

VLBI Very Long Baseline Interferometry

156 |
ndex

A

Accelerographs, 64

Active control systems, 83-84

Active mass damping, 83

Active tendons, 83

Advocates, role of, 116

Air Force Office of Scientific Research, 133

Alaska, 42-43

Alquist-Priolo Act, 104

Amplification effects, 63-65

Applied research, 19

Architectural research, 136

Armenia, 6-7, 72

Australia, earthquake program, 144-146

Australian Geological Survey Organization, 145

Avalanches, 40

B

Base isolation, 80, 82-83

Basic research, 19

Basin effects, 64, 66

Blind thrust faults, 44

Borehole volumetric strainmeters, 55

Bridges, 86-88

Building Act of 1991, 152, 153

Building codes

China, 148-149

Japan, 150-151

United States, 78-79, 103-109

Building damage

accomplishments of federally sponsored research,

90

existing buildings, 84-86

future research needs, 90-93

new construction, 22, 75-84

types of damage, 8, 74-75

Building Officials and Code Administrators code,

78, 108

Building rehabilitation, 112

Building Research Association, 153

Building Seismic Safety Council, 78

C

California. See also specific locations by name

earthquake hazards, 43-46

earthquake prediction, 62

land-use planning, 104

San Andreas fault, 2, 39-40, 43-45

seismic retrofit in Los Angeles, 112-114

voluntary retrofit in Palo Alto, 115

California Division of Mines and Geology, 81-82,

130

California Institute of Technology, 81

Caltech. See California Institute of Technology

Caltech-USGS Broadcast of Earthquakes system, 81

Canada, earthquake program, 146-147

Casualties, 72-74

CDMG. See California Division of Mines and

Geology

Center for Earthquake Research in Australia, 145

Central United States, earthquakes, 48-49

Central United States Earthquake Consortium, 140

CERA. See Center for Earthquake Research in

Australia

China

earthquake prediction, 62

earthquake program, 147-149

Chinese Ten-Year Committee, 147

Cocos Plate, 151

Code adoption process, 108

Code enforcement, 108-109

Collapse, 74

CONCERT. See Coordinating Organization for

Northern California Earthquake Research and

Technology

Concrete frame buildings, 76

Construction costs, 79

Contents damage, 74-75

Cookbook codes, 107

Coordinating Organization for Northern California

Earthquake Research and Technology, 130

County Geologist Program, 105

Creepmeters, 55

| 157
158 | Reducing Earthquake Losses

Cripple walls, 76

Cross-agency coordination, 26-27

CUBE. See Caltech-USGS Broadcast of Earthquakes system

CUSEC. See Central United States Earthquake

Consortium

D

Data Management System, 133

Database, 27

Deaths, 6-7, 72-73

Demolition, 109-110

Disaster Prevention Radio Communications

Network, 151

Distributional impacts, 9

E

Early warning systems, 81-82

Earth Science Division, 132

Earth science research

changes needed, 20-21

forecasting, 58-59

foretelling earthquake effects, 61, 63-67

fundamental seismological research, 56

key findings, 67-69

objectives, 51, 53

paleoseismology, 56, 58

prediction, 58-63

programs, 132-133

reducing economic losses, 120-121

reducing loss of life, 119-120

regional tectonic studies, 53-56

Earthquake Assessment Committee, 149

Earthquake Commission, 152-153

Earthquake engineering, 135-136

Earthquake Hazard Mitigation Program, 132

Earthquake Hazards Reduction Act, 125-126

Earthquake Lifelines Project, 139

Earthquake notification systems, 81-82

Earthquake prediction, 58-63, 125-126, 147-150

Earthquake risk, 41-42

Earthquake systems integration, 136

Earthquakes. See also specific locations by name

California, 43-46

casualties, 72-74

Central United States, 48-49

congressional interest in, 9-10

Eastern United States, 49-51

effects at the earth’s surface, 36-41

effects of, 2, 4-9

factors limiting assessment, 51

forecasting, 58-59

geologic setting for, 36

Intermountain Seismic Belt, 46-48

key findings, 67-69

loss estimation, 4-5

major U.S. earthquakes, 3, 73

major worldwide earthquakes, 72, 144

methods of evaluating severity, 34

mitigation, 10-12

non-NEHRP agencies activities, 141-142

occurrence of, 1-2

Pacific Northwest, 42-43

seismicity of the U.S., 35

summary of U.S. hazards, 52

Eastern United States, earthquakes, 49-51

Economic losses, 8-9, 120-121

Education, 122

Elastomeric bearings, 80

Electricity systems, 89

Emergency Management Australia, 145

Engineering research

changes needed, 21-23

implementation, 121

Japan, 150-151

EQC. See Earthquake Commission

EWSs. See Early warning systems

Executive Order 12148, 126

Executive Order 12699, 12

Executive Order 12941, 12-13

F

Faulting, 34

Federal Agency Earthquake Activities homepage on

the Internet, 27

Federal buildings, 12-13

Federal disaster assistance, 27-29

Federal Emergency Management Agency

activities, 138-140

budget components, 15, 138

history, 137

lead agency designation, 126

policy focus, 12

program coordination, 25-27

Federal government. See also specific agencies by

name

accomplishments of sponsored research, 90

agencies, 141-142

role of, 20

Federal response planning, 140. See also Federal

Emergency Management Agency

FEMA. See Federal Emergency Management

Agency

Financial incentives, 31

Forecasting, 58-59

Foreshocks, 62

Fracturing, 34
Index | 159

G

GAO. See General Accounting Office

General Accounting Office, 137

Geodetic studies, 54-56

Geodimeters, 55

Geographical Information System, 65

Geological Survey of Canada, 146

Geotechnical engineering research, 136

GIS. See Geographical Information System

Global Geodetic Network, 155

Global Positioning System, 54, 134

Global Seismographic Network, 133, 155

GPS. See Global Positioning System

Ground failure, 40, 41, 65

Ground rupture, 40

Ground shaking, 2, 6, 37-38, 60

Groundwater table, 62

GSC. See Geological Survey of Canada

GSN. See Global Seismographic Network

H

Hazard insurance, 27-29

Hazard zones, 105

Hot spots, 63

I

IDNDR. See International Decade for Natural Disaster Reduction

IGNS. See Institute of Geological and Nuclear

Sciences

Implementation of seismic mitigation efforts

approaches to, 97-98, 104-105, 111-115

assessing risk, 99-100

assessing vulnerability, 100-102

direct measures for improvement, 122-124

earth science research measures, 119-121

engineering research measures, 121

factors affecting, 111, 114-119

modifying the built environment, 102-111

overview, 95-96

seismic hazard maps, 98-99

steps for application of seismic codes, 117

voluntary nature of, 96-97

In-fault measurements, 55

Incentives, 31, 124

Incorporated Research Institutions for Seismology,

133

Indirect losses, 8-9

Information-only approach, 19-20

Injuries, 7-8, 73-74

Institute of Geological and Nuclear Sciences, 152

Insurance, 27-29

Intensity, 34, 36

Intermountain Seismic Belt, earthquakes, 46-48

International Committee Conference of Building

Officials, 108

International Decade for Natural Disaster

Reduction, 147, 154

International earthquake programs, 143-155

Internet, 27, 131

Intraplate earthquakes, 2, 40

IRIS. See Incorporated Research Institutions for

Seismology

J

Japan

earthquake prediction, 62

earthquake program, 149-151

geodetic techniques, 54

U.S.-Japan Panel on Wind and Seismic Effects,

154-155

Japan International Cooperation Agency, 151

Japan Meteorological Agency, 149

JMA. See Japan Meteorological Agency

L

Land-use planning, 102-105

Landslides, 40

Large-Scale Earthquake Countermeasures Act, 149

Laser interferometry, 55

Lead agency, 26, 126

Life safety, 119-120, 121

Lifelines damage, 8, 23, 86-90, 92-93

Liquefaction, 40, 65

Loma Prieta earthquake, 7, 9, 74, 86-87

Los Angeles Seismic Ordinance, 112-114

Loss estimation, 4-5

M

Magnitude, 34

Mass damping, 83

Mechanical systems research, 136

Mercalli Intensity scale, 34, 37

Mexico, earthquake program, 151-152

Mexico city earthquake, 41

Microzonation, 68-69

Minimum Design Loads for Buildings and Other

Structures, ASCE-7-93, 108

Mississippi River, 48

Mitigation, 10-12, 23-24

Mitigation advocates, 116

MMI. See Modified Mercalli Intensity scale

Model codes, 108

Modified Mercalli Intensity scale, 34, 37

Moment magnitude scale, 34, 36

Moral hazards issue, 29
160 | Reducing Earthquake Losses

Multi-hazard assessment, 140

Multiagency coordination, 26-27

N

National Building Code of Canada, 146

National Center for Earthquake Engineering

Research, 14, 135-136

National Earthquake Hazards Reduction Program.

See also NEHRP Provisions

allocating funding, 24-25, 130

budget, 128

challenges, 18-20

contributions of program, 16-17

contributions to earthquake engineering, 90

description, 13-16

federal disaster assistance, 27-29

financial incentives, 31

implementation gap, 17-18

insurance, 27-29

policy focus, 12-13

policy options, 20

portfolio changes, 20-25

reauthorization history, 126-128

regulation, 30-31

role of, 118-119

structural and operational changes, 25-27

National Earthquake Information Center, 131, 132

National Institute of Standards and Technology

accomplishments, 90

activities, 141

authorization of, 126

description, 15-16

funding history, 140

international cooperation and coordination, 155

policy focus, 12

National Mitigation Strategy, 26

National Oceanic and Atmospheric Administration,

66

National Research Council, 81

National Research Institute for the Earth Sciences

and Disaster Prevention, 150

National Science Foundation

description, 14

earth science research, 132-135

earthquake engineering, 135-136

funding appropriations, 126

international cooperation and coordination, 154

policy focus, 12

National Seismograph Network, 58

National Society for Earthquake Engineering, 153

Natural Disaster Fund, 152

Natural gas systems, 89-90

Natural Hazards Research and Applications Information Center, 140

NCEER. See National Center for Earthquake Engineering Research

NEHRP. See National Earthquake Hazards Reduction Program

NEHRP Provisions, 78, 108, 138-140

NEIC. See National Earthquake Information Center

New Madrid earthquakes, 48-49

New Madrid seismic zone, 49

New Zealand, earthquake program, 152-153

Newmark-Stever report, 125

NIST. See National Institute of Standards and

Technology

Nonstructural building components, 106-107

Nonstructural damage, 74

North American Plate, 39

Northeastern States Earthquake Consortium, 140

Northridge earthquake, 9

NSF. See National Science Foundation

NSN. See National Seismograph Network

Nuclear Regulatory Commission, 58

Nucleation phase, 61

O

Open Partial Agreement on Major Hazards of the

Council of Europe, 155

Oregon, 42-43

Outages, 86

P

Pacific Northwest, earthquakes, 42-43

Pacific Plate, 39

Paleoseismology, 56, 58

Parkfield (CA) prediction experiment, 62

PASSCAL. See Program for Array Seismic Studies

of the Continental Lithosphere

Plate tectonic theory, 118

Post Earthquake Evaluation Program, 155

Post-earthquake investigation program, 132

Precast concrete, 76

Precursors, identifying, 62

Prediction, 58-63, 125-126, 147-150

Private preparations, 110-111

Probabilistic forecasting, 59

Program coordination, 25-26

Program for Array Seismic Studies of the Continental Lithosphere, 133

Prudent Business Practices program, 139

Public outreach, 122, 124

R

Rapid Array Mobilization Program, 133

Rapid Earthquake Data Integration system, 81

R&D. See Research and development

Reauthorizations, 126-128
Index | 161

Recommended Lateral Force Requirements and

Tentative Commentary, Blue Book, 108

Recurrence interval, 58

REDI. See Rapid Earthquake Data Integration

system

Reelfoot Rift, 48-49

Regional tectonic studies, 53-56

Regulation, 30-31

Reinforced masonry, 76

Remote sensing, 55

Research and development, 19, 33

Research grants, 132-133

Resource Management Act of 1991, 152, 153

Retrofitted bridges, 87-88

Retrofitting, 22, 84-86, 109-110, 112-115

Richter magnitude scale, 34, 36

Ridge effects, 64

Robert T. Stafford Disaster Relief and Emergency

Assistance Act, 12

Russia, earthquake program, 153-154

S

Salt Lake County Natural Hazards Ordinance, 105

San Andreas fault, 2, 39-40, 43-45

SCEC. See Southern California Earthquake Center

Sedimentary basins, 64, 66

Seiches, 65-67

Seismic Belt, earthquakes, 46-48

Seismic codes. See Building codes

Seismic Hazard Committee, 115

Seismic hazard maps, 68, 98-99

Seismic hazards, 41-51

Seismic monitoring, 57-58

Seismic-resistant features, 79

Seismic retrofit action, 112-114

Seismic waves, 34, 37

Seismic zones, 59, 148-149

Seismological research, 56

Seismology, 118

Seismometers, 56, 57

Setbacks of buildings from faults, 104

Sewer systems, 88-89

Shear walls, 76

Sister cities, exchange of ideas and expertise

between, 130-131

Small-scale preparations, 110-111

Social science research, 122, 124

Societal losses, 9, 71

Soft stories, 75-76

Southern Building Code Congress International, 78,

108

Southern California Earthquake Center, 130,

134-135

Special Study Zones, 104

State and Local Hazards Reduction Program,

139-140

State Engineering Codes, 153

Steel-frame buildings, 77

Steel-weld problem, 77

Strainmeters, 55

Strike-slip plate boundaries, 39-40

Strong motion recording, 64

Structural components, 106

Structural damage, 74

Structural failure, 74

Structural research, 136

Study Zones, 104

Subduction zones, 39

Supplemental appropriations bills, 9, 28

Surface faulting, 40

Synthetic aperture radar imagery, 55

Systems preparations, 110-111

T

Technical assistance, 122

Tectonic plates, 2, 36, 38

Tectonic studies, 53-56

Tendon systems, 83

Thrust faults, 39

Tsunamis, 6, 65-67

Two-stage design process, 150

U

UBC. See Uniform Building Code

UNAVCO. See University Navstar Consortium

Unengineered structures, 107

Uniform Building Code, 78, 108

United Nations Educational, Scientific and Cultural

Organization, 155

United Nations International Decade for Natural

Disaster Reduction, 147, 154

United States. See Eastern United States; Western

United States; specific states and cities by name

United States-Japan Panel on Wind and Seismic

Effects, 154-155

University Navstar Consortium, 135

Unreinforced masonry, 76, 85

URM. See Unreinforced masonry

U.S. Geological Survey

description, 13-14

earthquake notification systems, 81

earthquake-related R&D, 33

funding appropriations, 126

future direction of, 131

geographic focus, 130

goals, 129-130
162 | Reducing Earthquake Losses

international cooperation and coordination, 154

policy focus, 12

post-earthquake investigation program, 132

seismic hazard maps, 98-99

spending under NEHRP, 131

technology transfer, 130-131

USGS. See U.S. Geological Survey

Utah, land-use planning, 105

V

Very Long Baseline Interferometry, 54

Visiting scholars, 27

VLBI. See Very Long Baseline Interferometry

W

Wasatch fault zone, 47

Washington, 42-43

Water and sewer systems, 88-89

Water waves, 40. See also Tsunamis

Western States Seismic Policy Council, 140

Western United States, 50

Whining, 18-19

Wood frame buildings, 76

Z

Zoning, 102-105