Dwelling and Mobile Home Monetary 

Losses Due to the 1989 Loma Prieta, 

California, Earthquake with an Emphasis 

on Loss Estimation

U.S. GEOLOGICAL SURVEY BULLETIN 1939-B
COVER: "***the cracks look like the stuff of nightmares. They snake through yards and across roadways .... [and] Summit 

Road from Highway 17 to Loma Prieta. The most impressive, three feet wide and seven feet deep, runs in front of John and 

Freda Tranbarger's house on Summit***". Photograph by Jim Gensheimer, October 24, 1989. Published November 30, 1989, 

in San Jose Mercury News and reproduced by permission. The photo, taken 7 days after the earthquake, shows water in the 

cracks due to the previous day's rainfall, thereby degrading the cracks.
Chapter B

Dwelling and Mobile Home Monetary 

Losses Due to the 1989 Loma Prieta, 

California, Earthquake with an Emphasis 

on Loss Estimation

By KARL V. STEINBRUGGE and RICHARD J. ROTH, JR.

Prepared in cooperation with the

State of California Department of Insurance

U.S. GEOLOGICAL SURVEY BULLETIN 1939

ESTIMATION OF EARTHQUAKE LOSSES TO HOUSING IN CALIFORNIA
U.S. DEPARTMENT OF THE INTERIOR 

BRUCE BABBITT, Secretary

U.S. GEOLOGICAL SURVEY 

Gordon P. Eaton, Director

Any use of trade, product, or firm names

in this publication is for descriptive purposes only

and does not imply endorsement by the U.S. Government

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1994

For sale by

U.S. Geological Survey, Map Distribution 

Box 25286, MS 306, Federal Center 

Denver, CO 80225

Library of Congress Cataloging in Publication Data

Steinbrugge, Karl V.

Dwelling and mobile home monetary losses due to the 1989 Loma Prieta 

earthquake : with an emphasis on loss estimation / by Karl V. Steinbrugge and 

Richard J. Roth, Jr.

c. cm. (U.S. Geological Survey bulletin ; 1939-B) (Estimation of 

earthquake losses to housing in California ; ch. B)

"Prepared in cooperation with the State of California Department of 

Insurance."

Includes bibliographical references.

1. Insurance, Earthquake California San Francisco Bay Region 

Adjustment of claims. 2. Dwellings Earthquake effects California San 

Francisco Bay Region Costs. 3. Mobile homes Earthquake effects 

California San Francisco Bay Region Costs. 4. Earthquakes California 

Loma Prieta. 5. Earthquakes California San Francisco Bay Region. 

I. Roth, Richard J. II. California, Dept. of Insurance. III. Title. IV. Series. 

V. Series: Estimation of earthquake losses to housing in California ; ch. B. 

QE75.B9 no. 1939-B 

[HG9981.35.C2 

557.3 s dc20

[363.3'4] 94-33201

CIP
CONTENTS

Abstract Bl 

Acknowledgments Bl 

Wood frame dwellings B2 

Introduction B2

Characteristics of the earthquake B2 

Seismic model B3 

Terminology and definitions B3 

Determining monetary losses from insurance data B5 

Source A: California Department of Insurance B5 

Source B B6

Postal ZIP codes and distances from earthquakes B8 

Dwelling losses before and after deductible B8 

Probable maximum loss (PML) BIO

Definition of probable maximum loss (PML) BIO 

Definition of PML zone B12 

Losses in the Loma Prieta PML zone B12 

Losses by age groups B12 

Elimination of losses due to major geohazards B13 

PML and loss over deductible B14 

Loss over deductible ZIP basis B15 

Loss over deductible zone basis B18 

Loss over deductible Watsonville study area basis B18 

Loss over deductible other California experience B21 

PMLs and equations for loss over deductible B22 

Size of the PML zone B24

Loma Prieta earthquake B24 

Smaller magnitude earthquakes B24 

1906 San Francisco earthquake B24

Estimation of loss over deductible and PMLs for other magnitudes B25 

Post-1939 construction B25

1992 Landers earthquake: California residential earthquake recovery plan

deductible B27 

Pre-1940 construction B28 

Dwelling contents losses B29 

Additional living expense (Ale) for dwellings B31 

Geographic distribution of losses B31 

Construction and value as variables B33 

Modified Mercalli intensity B35 

Mobile homes (manufactured housing) B35 

Introduction B35

Definition of mobile home (manufactured housing) B35 

Characteristic damage B37 

Loma Prieta earthquake B37 

Source B data B37 

Source C data B41

California Department of Housing and Community Development B43 

Experience from previous earthquakes B45 

1971 San Fernando earthquake B45

Observations on San Fernando B48 

1978 Santa Barbara earthquake B49 

Observations on Santa Barbara B51

Contents III
Mobile homes (manufactured housing) Continued 

Experience from previous earthquakes Continued

1979 El Centre (Imperial Valley) earthquake B51 

Test of rapid loss estimation, El Centre B52

1980 Livermore (Greenville) earthquakes B52

1983 Coalinga earthquake B53 

Synthesis and overview B54

PML zone B54

Loss over deductible in the PML zone B54

Maximum losses in the PML zone B55

Loss attenuation with distance B56

Earthquake bracing B57

Coach size and damage B57

Loss estimation from rapid field inspections B57 

Summary, major findings, and conclusions B57 

Wood frame dwellings B57

Dwelling loss versus other losses B57

PML zone and modified Mercalli intensities B57

Dwelling age and loss B57

Geohazards B58

Deductibles B58

Loss attenuation with distance B58

Contents losses B58

Ensuing fire B58

Research needs B59 

Mobile homes (manufactured housing) B59

Nonbraced mobile homes B59

Earthquake bracing B59

Loss attenuation B59

Research needs B59

Comparative losses: Wood frame and mobile homes B59 

References B59

Appendix A. Sensitivity: Loss over deductible versus dwelling PML changes B61 

Appendix B. Definitions of degree of damage to mobile homes B61

FIGURES

1. San Francisco Bay Area counties in the Loma Prieta earthquake study area, which 

is bounded by a solid line with dots. B2

2. Diagrammatic cross section through the fault (view is northwest) modeling the 

earthquake's line source and zone source of seismic energy. B3

3. Epicentral area of the Loma Prieta earthquake. The heavy black line is the surface 

projection of the modeled line source of the seismic energy. The diamond at the 

midpoint of the heavy black line is the epicenter. See figure 2 for the model of the 

line source. The closed loop about the heavy black line is the limit of the probable 

maximum loss zone (PML zone, defined in section "Definition of PML 

Zone"). B5

4. Postal ZIPs in epicentral area of the Loma Prieta earthquake. See figure 3 for 

relationships to the topography. ZIPs limited to portions of Santa Cruz and Santa 

Clara Counties. ZIP boundaries in the Santa Cruz Mountains are uncertain. Map 

adapted from "ZIP Codes in the San Francisco Bay Area" by permission of the 

copyright owner, Western Economic Research Co., Panorama City, California. 

Heavy black line and loop are explained in figure 3. B9

5. Percent loss over deductible at 10 percent deductible plotted against distance from 

the fault. See text for discussion. Watsonville study area is defined in section 

"Loss Over Deductible Watsonville Study Area" and in figure 7. B16 

IV Contents
6. Average paid building loss per earthquake insured building plotted against distance 

from fault. See text for discussion. B18

7. Watsonville study area and Watsonville city limits. Solid triangles are locations of 

mobile home parks; park numbers are identified in table 26. Open circles are 

structures outside of the central business district posted as hazardous after the 

earthquake. B20

8. Loma Prieta and Coalinga loss over deductible data with each normalized at 10 

percent deductible. Also shown is the range of normalized loss over deductible 

data for all ZIPs in the PML zone at 20 percent deductible. B22

9. Expansion of a portion of figure 8 including the Watsonville study area. The Watsonville study area data essentially overlaid the Coalinga curve in figure 8. The 

solid circles are for the Loma Prieta PML zone. The open circles are for the 

Watsonville study area. B23

10. Loss over deductible for magnitudes 5 (threshold of building damage); magnitude 

6.9 (equation 5, basis for equation 7); 7.75 (reasonable upper limit), and 8.25 

(1906 San Francisco with no upper limit). Curves from equation 7 with uncertainty factor of 1.0. B26

11. Equation 7 loss over deductible curve compared with Landers earthquake data. Upper 

right hand corner shows slope comparisons at 1 percent normalization. B28

12. Geographic distribution of average building loss as a percent of insured value 

using data source A information. Each open or solid circle represents the centroid 

of a postal ZIP having more than 10 wood frame earthquake insured buildings. 

Solid circles have, on an ZIP average basis, losses equalling or exceeding 0.5 

percent. Open circles have lessor average losses or none. Solid circles with average losses equalling or exceeding 1.0 percent also show the percent loss. Data 

shown are from table 44 (at end of report) which differ slightly from those used in 

figure 5. B33

13. Another perspective on figure 12 data and those in table 44. The plot is paid

building loss plus deductible as a percent of value against distance from the fault. 

Loss percentages less than 0.5 percent are not plotted. B33

14. PML zone and its relationships to the Modified Mercalli intensity zone VIII. Also 

shown is the boundary of the ZIPs with centroids within the PML zone. B36

15. Loma Prieta earthquake. Mobile home loss over 10 percent deductible as a function of distance from the fault for parks are grouped by ZIP; in figure 16, parks 

are individually plotted. Excluded are ZIPs with no losses or fewer than 10 mobile homes. Names are post office names and may include large rural areas. Data 

from source B. B38

16. Loma Prieta earthquake. Percent loss over 10 percent deductible as a function of 

distance from the fault for individual mobile home parks; in figure 15, parks are 

grouped by ZIP. Solid triangles are parks located in Watsonville ZIP 95076. Solid 

circles are parks in a coastal community, or nearby. Open circles are parks to the 

east of the fault, ranging from the Santa Clara Valley to Hollister. Data from 

source B. B39

17. Loma Prieta earthquake. Percent of fallen mobile homes as a function of distance 

from the fault. Numbers beside the solid circles are the park numbers identified in 

table 31. Source is California Department of Housing and Community Development (1989?, p. 2). B45

18. 1971 San Fernando earthquake region showing the locations of mobile home parks. 

Numbers adjacent to the solid triangles are park numbers found in table 32. B47

19. 1971 San Fernando earthquake. Percent loss over deductible as a function of distance for individual mobile home parks. Numbers are park numbers identified in 

table 32. B48

20. 1978 Santa Barbara earthquake region showing epicenter and approximate location 

of the mobile home parks (solid circles). Numbers beside the circles are identified 

in table 35. B50

Contents
21. 1979 El Centre earthquake region showing mobile home parks (solid triangles). 

Numbers by the triangles are park numbers identified in table 36. B51

22. 1980 Livermore (Greenville) earthquake region showing approximate location of 

surface breakage associated with faulting. Numbers by the solid triangles are park 

numbers identified in the text. B52

23. Percent loss over deductible as a function of percent deductible. Curve for coaches 

is based on equation 11 for magnitude 7.75. That for coach and contents is based 

on equation 12, also for magnitude 7.75. B56

TABLES

1. Summary of insurance losses paid for all lines of insurance B6

2. Homeowner (Ho.) dwellings and paid earthquake (Eq.) losses B7

3. Percent of homeowner earthquake insured dwellings having paid losses B7

4. Percentage of homeowners policies also with earthquake coverage B8

5. Santa Cruz County paid losses (portion of computer hard copy) Bll

6. Number of insured dwellings from source B data grouped by decade B12

7. Homeowner insured dwellings from source B data, with or without earthquake 

coverage B13

8. Paid losses to dwellings with earthquake coverage grouped by decade B13

9. Geohazard grades for dwellings in source B data B14

10. Paid losses and values as function of percent deductible for dwellings in PML 

zone B15

11. Percent loss over deductible for dwellings in ZIPs 10 miles or less from the fault 

as a function of percent deductible (defined in table 10) B17

12. Effect of geohazards on loss over deductible in PML zone ZIPs B19

13. Percentage loss over deductible data for 1989 Loma Prieta and 1983 Coalinga 

earthquakes as a function of percent deductible B19

14. Loss over deductible comparisons at 10 percent deductible B21

15. Percentage loss over deductible as a function of percent deductible for varying 

earthquake magnitudes B27

16. Contents loss as percent of building loss as a function of percent deductible B29

17. Contents loss as a percent of building value for nine-county study area B30

18. Ale loss as percent of building loss as a function of percent deductible B30

19. Building losses for selected ZIPs at distant locations B31

20. Number of stories as a function of building losses B34

21. Type of roof as a function of building losses B34

22. Masonry chimneys as a function of building losses B34

23. Value as a function of earthquake insurance coverage B34

24. Mobile home (manufactured housing) losses in 14 counties B37

25. Mobile home losses 10 miles or less from the fault B38

26. Coach loss data on selected mobile home parks B40

27. Type of foundation anchorage for mobile homes B40

28. Relationships among losses and values for mobile home coaches, contents, and 

Ale B41

29. Mobile homes with paid losses in the PML zone B42

30. Relationships among losses and values for mobile home coaches, contents, and 

Ale B42

31. Mobile home performance in the 1989 Loma Prieta earthquake, insurance and 

non-insurance data B44

32. Mobile home loss experience from 1971 San Fernando earthquake, magnitude 

6.4 B46

33. Average loss to mobile home components, 1971 San Fernando earthquake, magnitude 6.4 B49

VI Contents
34. Wood frame dwelling versus mobile home losses for 1971 San Fernando earthquake, magnitude 6.4, zero deductible B49

35. Average loss to mobile home components from 1978 Santa Barbara earthquake, 

magnitude 5.1 B50

36. Average loss to mobile home components from 1979 El Centro (Imperial Valley) 

earthquake, magnitude 6.4 B51

37. Mobile home damage from 1979 El Centro (Imperial Valley) earthquake, magnitude 6.4 B52

38. Mobile home damage in park 1 from 1980 Livermore (Greenville) earthquakes, 

magnitudes 5.5 and 5.6 B53

39. Mobile home damage from 1983 Coalinga earthquake, magnitude 6.7 B53

40. Performance of mobile home supports in 1983 Coalinga earthquake, magnitude 

6.7 B53

41. Mobile home loss over deductible in PML zone B54

42. Loss over deductible as a function of deductible, in percent B55

43. Comparison of losses to mobile homes B56

44. Building, contents, and Ale losses, before and after deductible B63

Contents VII

Dwelling and Mobile Home Monetary Losses

Due to the 1989 Loma Prieta, California, Earthquake,

with an Emphasis on Loss Estimation

By Karl V. Steinbrugge1 and Richard J. Roth, Jr.2

Abstract

Our overall objective is to improve the methodology of 

monetary loss estimation for wood frame dwellings and mobile homes by using earthquake insurance loss information 

based on specific data gathered after the Loma Prieta earthquake. Wherever applicable, it is intended to replace methodologies based on the Modified Mercalli scale. Loss data 

used were gathered by the California Department of Insurance and supplemented from other insurance sources. These 

data were compared and analyzed with similar information 

from all available California earthquakes.

Detailed loss data from the Loma Prieta earthquake 

were obtained from over 55,000 paid claims, which comprised all forms of insurance including those on dwellings. 

More detailed, supplementary information on 85,382 wood 

frame dwellings was obtained on loss (if any), construction 

variations, and many other components. Of these dwellings, 

5,530 had paid losses in the study area, which includes nine 

counties in the San Francisco Bay area. Data are deliberately 

presented in considerable detail since they are difficult to 

obtain directly from our sources. Several are used by permission from proprietary sources or otherwise are not generally 

available. The strong and weak aspects of our data are 

pointed out.

Wood frame dwellings constructed prior to 1940 experienced average losses exceeding twice those of later construction. Post-1939 dwellings in the epicentral region 

suffered about 6 percent average building loss when not subjected to landsliding or located on stable but steeply sloping 

sites. Average building losses at 10 miles from the fault were 

small, and at 20 miles were negligible. Major exceptions 

were in structurally poor ground areas with liquefiable soils,

Consulting Structural Engineer, El Cerrito, California. 

Chief Property/Casualty Actuary, California Department of Insurance, Los Angeles, California.

Manuscript approved for publication July 20, 1994.

where losses were magnified. A prime example was San 

Francisco's Marina District, which was 50 miles away.

Deductibles are normal in insurance policies, whether 

private or government. They are also sometimes found in 

on£ form or another in governmental grants. We developed 

loss over deductible equations which relate average homeowner loss that is, the loss absorbed by the homeowner, 

beyond that covered by insurance. The equations are on an 

aggregate basis and not applicable to individual structures 

and are principally for computer use in broad loss estimation 

calculations.

When collapse did not occur, reported contents losses 

were about 20 to 25 percent of the reported building loss on 

the average, admitting wide variations in valuations and susceptibilities among building and contents.

Mobile homes (manufactured housing), when not earthquake braced, were prone to fall off their supports. Within 

20 miles of the earthquake, about 15 percent of the approximately 2,500 fell from their supports. In sharp contrast, those 

braced to resist earthquake shaking had no known instances 

of falling.

ACKNOWLEDGMENTS

We appreciate the advice and guidance freely given 

by Dr. S.T. Algermissen, U.S. Geological Survey, especially on seismological aspects, including a review of the 

line source model representing the energy release from the 

Loma Prieta earthquake. His comments throughout the entire development of the manuscript were valuable.

Special acknowledgment is due to Mr. Robert L. 

Ocfrnan, retired Assistant Vice President of the State Farm 

Fire and Casualty Company, for his thoughtful examinatioh of the manuscript at various stages during its development. His engineering background provided technical 

insights to the engineering aspects as well as to the nuances of insurance company practices.

The City of Watsonville provided assistance and insights during the examination of their original damage reports and maps relating thereto. Special thanks are due to

Dwelling and Mobile Home Monetary Losses Due to the 1989 Loma Prieta, California, Earthquake, with an Emphasis on Loss Estimation B1
Ms. Dicksie Lynn Alien, Associate Planner, and Mr. Kenneth N. Lewis, Senior Civil Engineer, both of whom devoted considerable time on several occasions.

Partial financial support for this study was provided 

by the U.S. Geological Survey and also by the California 

Department of Insurance.

WOOD FRAME DWELLINGS 

Introduction

On October 17, 1989, the 7.1 Richter magnitude 

Loma Prieta earthquake significantly damaged structures 

in northern California (fig. 1) from the Pacific coast 

beaches, east to include western Santa Clara County, north 

50 miles to include San Francisco County, and south to 

include northern San Benito and northern Monterey Counties. The insurance industry paid out over a billion dollars 

to settle 56,667 claims (out of 112,513 claims reported) 

for all types of insurance coverages, from damage to structures and automobiles to life and medical coverages. The 

actual dollar loss was much greater than this, because 

about 70 percent of the private property was uninsured for 

earthquake damage, as well as practically all of the highway system and public buildings which sustained substanN 122.° 100' I j 121°] 00' .^'"' .x

\ f-* ' /' ^.J 7.^* /X

T^^' V / 3^ :\ .' J£_

! \ / 00>

^.^

SCALE, IN MILES 

_____122°100' \i2r'loo ;

Figure 1. San Francisco Bay Area counties in the Loma 

Prieta earthquake study area, which is bounded by a solid 

line with dots.

tial damage. When the insured and uninsured private 

property damage is combined with the damage to public 

highways, bridges, and buildings, and combined with the 

economic losses, direct and indirect, the total loss from the 

Loma Prieta earthquake rises to about $10 billion.

Our data on monetary loss estimation for wood frame 

dwellings constitute one component of these losses for 

which substantial loss data are available. Our findings are 

intended as one basis to estimate monetary loss for earthquakes in areas where geophysical conditions are similar. 

Potential users include disaster response planners, both 

governmental and private, as well as financial entities such 

as insurance companies. Findings are also intended to be 

useful for legislative and policy planning as well as for the 

general public.

Quantifying monetary losses for postulated future 

earthquakes has relied heavily on isoseismal maps prepared after earthquakes, a method which we believe is 

overly judgmental for loss estimation purposes. Our approach, based on actual monetary loss experience, is compared with those based on intensities.

Numerical values found throughout the text and tables are usually much less precise than those given; actual 

values may vary within 50 percent of the given values. 

However, high precision is characteristic for values of exponential functions and also for small differences between 

large numbers. Distances are normally expressed in miles 

as well as kilometers to accommodate the nonscientific 

reader.

Characteristics of the Earthquake

The earthquake's origin time was 5:04:15 p.m. (PDT) 

on October 17, 1989. Seismic data for it differ slightly 

among authorities, but the variations are insignificant for 

our purposes. Used for this analysis is the information by 

McNutt and Toppozada (1990, p. 12):

Latitude: 37°02.33' N.±l km

Longitude: 121°52.76' W.±l km

Focal depth: 17.6 km ±1 km

Magnitude: Ms 7.1 based on 21 observations

Fault plane: Strike N. 50°±10° W.

Dip 70°±15° SW.

Rupture length was given as 40 km (p. 16). The 17.6 km 

focal depth was greater than the more common 10 km. 

Benuska (1990, p. 9) states "During the next seven to ten 

seconds [after the faulting began] the rupture spread approximately 20 km both to the northwest and southeast...." 

Additional detail may be found in Plafker and Galloway 

(1989).

Based on the foregoing, the model has a 40 km line 

source, centered at the longitude and latitude stated above, 

and having a strike of 50° NW. The epicenter is at the 

middle of the line source. Figure 2 is a cross section

B2 Estimation of Earthquake Losses to Housing in California
through the fault. Figure 3 is a topographic map of the 

epicentral area including adjacent areas in Santa Cruz and 

Santa Clara Counties. The heavy black line in this figure 

is the surface projection of the line source of the modeled 

Loma Prieta faulting. The diamond in the center represents 

the epicenter. The closest important community to this line 

is Watsonville.

Seismic Model

Distance from an earthquake is one factor which will 

greatly influence dwelling damage. The seismic energy released during an earthquake is contained in the volume of 

rock surrounding the slippage on the fault plane. This energy attenuates with distance, and this distance must be 

accounted for in predictive loss estimation algorithms.

Our model assumes that seismic energy can be considered as a line source located on the fault plane at the 

focal depth of the earthquake (fig. 2). The horizontal 

length of the line source is the same as the horizontal 

length of the rupture on the fault plane. For some earthquakes this length may be determined from the length of 

the surface breakage along the fault. Inasmuch as surface 

faulting for the Loma Prieta earthquake was absent or obscured by surficial features, the distribution of aftershocks 

and other seismically determined factors such as faultplane solutions were used to estimate the dimensions of 

the causative fault.

.Faulting

Fault to ZIP Fault to ZIP 

centroid distance ^ centrold distance ^

Upper plate EPICENTER Lower plate

Zone sources 

seismic energy

Figure 2. Diagrammatic cross section through the fault 

(view is northwest) modeling the earthquake's line source 

and zone source of seismic energy.

Terminology and Definitions

Summarized below are certain abbreviations and 

word usages found in the text and tables. These are further 

explained and discussed elsewhere in the text.

HO or homeowners multiple peril policy. This is the 

basic homeowners policy. The term "dwelling(s)" when 

used in this context includes structures and their contents; 

"building(s)" refers only to structures. The policy covers 

many perils, especially fire, but specifically excludes 

"earth movement." "Earth movement" includes landslide 

and earthquake. An earthquake endorsement has the effect 

of reversing this exclusion with respect to earthquake, but 

at a much higher deductible than the basic policy deductible. It is possible to buy a separate earthquake insurance 

policy which has the same effect. There is no known insurance available for nonseismic landslide. The earthquake 

endorsement will apply only if the landslide is caused by 

earthquake; technically the policy insures only the replacement of the structure, not the land, but the land would obviously have to be replaced to rebuild the house. The 

combination homeowners policy (HO) and earthquake endorsement (EQ) provides these five coverages (in order of 

importance in terms of earthquake losses):

(1) Coverage for damage to the structure up to the 

stated limit or replacement cost, whichever is 

specified, subject to a deductible. The deductible 

is usually 10 percent of the insured limit, but 

may be 5 or 15 percent or a combined deductible for all coverages.

(2) Coverage for contents, which is limited to 50 or 

75 percent of the structure limit and is usually 

subject to its own deductible, but the deductible 

may be combined with the structure deductible.

(3) Coverage for "loss of use," which includes additional living expense and fair rental value. There 

is no deductible, but the limit is usually one 

year. "Ale" and ALE" (additional living expense) when used in the tables or the text has 

the same meaning.

(4) The main homeowners policy covers fire and, in 

most policies, breakage of glass from an earthquake even if no earthquake endorsement is purchased, often with a $250 deductible.

(5) Coverage for secondary buildings, such as detached garages and out buildings.

A renters policy covers only contents and loss of use.

A condominium unitowner policy ("Condo") is 

broader than a renters policy, but the condominium association insures the structure. Additional living expense is 

also included in many cases.

The term "mobile home" includes the coach, contents, and appurtenances unless context indicates otherwise. Mobile homes and manufactured housing are 

considered to be synonymous in this study.

Dwelling and Mobile Home Monetary Losses Due to the 1989 Loma Prieta, California, Earthquake, with an Emphasis on Loss Estimation B3

Determining Monetary Losses 

from Insurance Data

Paid insurance claims provide a substantially improved basis for monetary loss estimation of future earthquakes for two reasons. First, paid insurance claims 

represent the cost of repair and are therefore a direct 

measure of vulnerability. In contrast, when vulnerability is 

derived from physical damage, estimates of cost of repair 

must be made (of the various damaged structural and nonstructural components of a building, including depreciation 

if applicable) to calculate costs. Consequently, it is much 

more difficult to determine the percentage loss or cost of 

repair from damage data than it is from paid insurance 

claims. Second, cost of repair data need not be referenced 

to Modified Mercalli intensity for use in determining vulnerability. The use of paid insurance claims as the basis 

for building vulnerability relationships was suggested by 

Steinbrugge and others (1984).

Normally, private insurance has a deductible clause, 

wherein the insurer shares losses with the owner. This is also 

generally true in some related form where governmental 

insurance or assistance program is provided. Aggregate loss 

estimates for future earthquakes must necessarily consider 

the impact of deductibles (Steinbrugge, 1990). A percentage 

deductible is used in this study; percentages may readily be 

changed to dollars or to various combinations of dollars and 

percentages through simple mathematical computations.

Despite the advantages of using paid earthquake insurance claims, they have some disadvantages. The data 

base of paid claims that have been analyzed is restricted to 

California. Also, the location of each large claim should 

be field checked to ascertain if the claim is a result of only 

ground shaking or if ground failure such as landsliding or 

liquefaction has been a factor.

The Loma Prieta earthquake provided an unusual opportunity to examine relationships among values, monetary 

losses, and monetary loss attenuation with distance for 

dwellings and mobile homes. This event is unique in United 

States experience in that it has been the largest magnitude 

earthquake to date for which substantial amounts of reliable 

quantitative monetary loss data are available. [Note added 

in press: When monetary losses become available for the 

1994 Northridge, California, earthquake, they are expected 

to exceed those of Loma Prieta.]

The Loma Prieta study area is confined to nine counties (fig. 1) around the San Francisco Bay and Monterey 

Bay, as follows:

 ^ Figure 3. Epicentral area of the Loma Prieta earthquake. The heavy black line is the surface projection of the 

modeled line source of the seismic energy. The diamond at 

the midpoint of the heavy black line is the epicenter. See 

figure 2 for the model of the line source. The closed loop 

about the heavy black line is the limit of the probable maximum loss zone (PML zone, defined in section "Definition of 

PML Zone").

Alameda 

Contra Costa 

Marin

Monterey 

San Benito 

San Francisco

San Mateo 

Santa Clara 

Santa Cruz

Reliable insurance loss information came from two 

principal sources which are described below.

Source A: California Department of Insurance

On January 31, 1990, the California Department of 

Insurance issued a special data call for loss statistics relating to the Loma Prieta earthquake to all insurers licensed to 

do business in the State of California. Under the department's general regulatory authority, all insurers were required to respond. On February 15, 1991, the department 

issued a second data call to update the information from the 

first data call. This time, the insurers reported that the total 

incurred losses for all coverages as $901,762,236 on a total 

of 56,667 claims. No further information was requested 

from the insurers. No insurer became insolvent because of 

this earthquake. Information from this latter data call is 

referred to as "Source A" throughout this study.

Table 1 is a summary of some of the results received 

from 212 insurer groups. Most groups in turn have several 

licensed insurers, but under common management, and so 

the total number of insurers reporting actual losses was 

much greater. There are about 1,500 insurers licensed in 

California, half life and health and half property/casualty. 

The remaining insurers had few or no losses. The five largest groups paid out 70 percent of the residential losses, and 

the 15 largest groups paid out 90 percent of the residential 

losses. The fire losses are separately stated in table 1, since 

they are not covered under an earthquake policy but are 

paid under many lines of insurance in addition to the "fire" 

line of insurance. For instance, a loss under an earthquake 

endorsement attached to a homeowners policy may be allocated to the homeowner's line or to the earthquake line 

with any ensuing fire loss allocated to the homeowners line. 

Also, it is possible to have losses under a homeowners 

policy whether or not there was an earthquake endorsement 

(for example, for glass breakage or fire).

It is important to reiterate that our loss estimation study 

of wood frame dwellings is based on insurance data. For the 

Loma Prieta study area, our data base is limited because only 

30 to 35 percent of the dwellings had earthquake insurance; 

many owners of low-value dwellings, brick homes, or older 

homes perhaps chose not to insure because of the cost. 

Nevertheless, it does not appear that our results are seriously 

impacted by this shortcoming. In particular, the geographic 

distribution of insured dwellings seems to be fairly even. 

Another limitation to our data was that the amount the insurer paid was subject to the provisions of the insurance

Dwelling and Mobile Home Monetary Losses Due to the 1989 Loma Prieta, California, Earthquake, with an Emphasis on Loss Estimation B5
Table 1. Summary of insurance losses paid for all lines of insurance.

[From California Department of Insurance's second call for data (Source A, see 

text). "MP". multiple peril.]

Insurance Lines

Life

Accident and health

Fire

Allied lines

Farmowners MP

Homeowners MP

Commercial MP

Other liability

Inland marine

Earthquake

Workers compensation

Automobi le

Glass

Burglary and theft

Boiler and machinery

Other

Losses

Number of 

Reported

40

198

1,759

1,131

185

35,670

6,071

249

2,185

55,112

615

6,956

99

2

56

1,135

Other Than Fire

Claims 

Paid

40

196

743

295

98

17,864

1,604

193

1,548

26,291

496

5,539

89

2

6

710

Paid 

Losses 

x$1000

3,311

1,278

28,844

47,644

2,411

162,839

101,940

7,059

109,624

397,727

3,576

8,563

216

6

329

6,406

Fire

Number of

Reported

..

--

170

15

2

725

63

6

14

--

--

--

--

--

--

55

Losses Only

Claims

Paid

--

148

11

0

687

43

6

14

--

--

--

--

--

--

44

Paid 

Losses 

x$1000

..

--

3,042

42

0

12,283

4,177

19

9,829

--

--

--

--

--

--

417

TOTAL 111,463 55,714 881,772 1,050 953 19,990

contract that is, there are limits, deductibles, and exclusions. In many cases, the dollar losses as reported are net 

amounts (total loss less deductible usually about $10,000 

to $15,000), and so the deductible had to be estimated or 

computed and added back in order to obtain the gross losses. 

Data for mobile homes (manufactured housing) had 

many of the same constraints which applied to wood 

frame dwellings.

Source B

Source B information was obtained by one of the authors (Steinbrugge) from a company which also reported to 

the California Department of Insurance's call for data. This 

data source contains substantially greater amounts of information than that acquired by the department. The advantage 

of this additional information is that it facilitated estimates 

of losses due to geologic effects, particularly landsliding. 

Additionally and most importantly, its data contained information on all of their insured dwellings, whether insured for 

earthquake or not and whether losses were paid or not. This 

allowed the calculation of percentage loss as a function of 

all insured dwellings in a specified region such as a ZIP code 

area. These loss percentages are crucial to the methods of 

loss estimation for future earthquakes.

Source B has a 20 percent market share. The geographic distribution of its insureds was reasonably uniform 

throughout the Loma Prieta study area. Their underwriting 

practices did not influence market share in potentially geologically hazardous areas such as landslide regions in the 

epicentral region and elsewhere, nor in the "poor ground"

areas such as the heavily damaged San Francisco Marina 

District and other districts such as the reclaimed lands of 

Foster City on the San Francisco Peninsula. In short, there 

appears to have been no biases relating to the issuance of 

policies and building values.

Table 2 shows that 85,382 dwelling earthquake insurance policies from source B were in force in the study 

area at the time of the Loma Prieta earthquake. Data are 

listed by county in order to provide an overview of the 

geographic distribution of the policies, paid insurance 

losses, and their paid amounts. Except for the most distant 

areas of some counties, each insured dwelling probably 

felt the earthquake though it may or may not have had 

damage. The third column lists the number of dwellings 

having building losses which exceeded the insurance deductible; the fourth column pertains to dwellings with contents losses; the fifth column refers to the number of 

houses which were uninhabitable for some period of time 

due to damage. Detailed data were available for all 

242,789 dwellings. Of these 242,789 dwellings, only 302 

were identified as being of masonry construction (masonry 

dwellings are therefore not part of this study).

Table 3, column 4, shows the density of the loss data 

in terms of the percentage of insured dwellings with paid 

losses. Counties are ranked by these percentages. Clearly, 

Santa Cruz County was the most heavily hit, followed by 

San Francisco, San Benito, Santa Clara, and Monterey 

Counties. It should be noted in figure 1 that San Francisco 

County is more distant from the earthquake than San Mateo 

County but that the percentage of insured dwellings with 

paid losses is larger. This is attributable, at least in part, to

B6 Estimation of Earthquake Losses to Housing in California
Table 2. Homeowner (Ho.) dwellings and paid earthquake (Eq.) losses. 

[Data from source B, see text.]

County

Alameda

Contra Costa

Mar in

Monterey

San Benito

San Francisco

San Mateo

Santa Clara

Santa Cruz

Number of Insured Dwel lings 

Ho. Ed.

56,226

45,465

10,356

11,963

1,013

13,038

30,018

64,281

10,429

19,421

13,698

3,312

2,230

354

3,378

11,948

28,077

2,964

Dwellings With Eq. Insurance Having:

Paid Loss on: 1

Bldq.

224

82

13

88

46

194

228

2,015

2,640

Conts.

31

18

4

84

59

82

71

1,151

1,865

Ale2

10

4

0

29

4

21

12

309

422

Amount

Bldq.

2,091

885

76

503

257

2,823

2,516

34,093

30,342

of Paid

Conts.

128

36

96

192

61

281

580

8,376

6,581

Loss: 3

Ale4

50

19

0

47

36

85

55

2,981

2,209

Totals 242,789 85,382 5,530 3,365 811 73,586 16,331 5,482

:A dwelling may have a paid loss in each of the three columns, or 

combination thereof, and be counted in each column in which a paid loss occurred.

2Ale means "additional living expense," which is paid when homeowner is 

unable to occupy dwelling due to earthquake damage.

3 In thousands of dollars.

Table 3. Percent of homeowner earthquake insured 

dwellings having paid losses.

[Source B, see text.]

Earthquake 

Insured 

County Dwellings

Santa Cruz

San Francisco

San Benito

Santa Clara

Monterey

San Mateo

Alameda

Contra Costa

Mar in

2,964

3,378

354

28,077

2,230

11,948

19,421

13,698

3,312

Dwellings 

With Paid 

Loss 1

1,534

318

33

1,920

79

286

223

82

14

Percent of 

Dwellings 

With Paid Loss

51.8

9.4

9.3

6.8

3.5

2.4

1.1

0.6

0.4

be counted, dwellings must have any combination 

of paid building, contents, and Ale Loss. In 

contrast, the count in column 3 of table 2 is 

for dwellings having building damage; contents 

for column 4, and Ale for column 5.

the intensified damage in the Marina District of San Francisco, where high site response due to structurally poor 

ground conditions increased the damage compared to adjoining districts. A second reason is that single family 

dwellings in large sections of San Francisco have certain 

characteristics not common throughout the Loma Prieta 

study area.

Many of these wood frame structures are located on 25-foot lots, 

or somewhat wider, and often no space exists between the sides 

of adjoining buildings. Also these homes are conventionally two 

story. The garage, laundry areas, storage areas, etc., are in the first 

story; the second story is living space. An arrangement of this 

type leads to numerous partitions in the second story with a minimum number of partitions in the first story. The front wall in the 

first story has numerous openings. The rear wall of the first story 

has fewer openings than the front.... The result is a building 

which in general is weak in the first story, especially against 

transverse lateral forces. (Steinbrugge and others, 1959, p. 76. See 

also pages 76/83 for types of damage.)

Third, the houses were, on the average, older than those 

elsewhere in the study area.

Table 4 shows the percentage of the homeowners policies for sources A and B which included earthquake insurance. At the time of the earthquake, California state law 

required every insurance company writing dwelling coverages to also offer earthquake insurance. This offer was 

made in writing to each fire insured policy holder. Therefore, the percentages are indicators of the public's awareness of the earthquake hazard and insurance response 

thereto. The first five counties in the table include one or 

more of the San Andreas, Hayward, and Calaveras faults 

within their boundaries. These faults are well-publicized 

and locally well-known, and can account for the high percentages. Except for San Francisco, the percentage of 

homeowners carrying earthquake insurance was consistent 

between the two data sources.

The numerous popular books on the great 1906 San 

Francisco earthquake have been on booksellers shelves for 

many years. Structurally poor ground regions of the Marina

Dwelling and Mobile Home Monetary Losses Due to the 1989 Loma Prieta, California, Earthquake, with an Emphasis on Loss Estimation B7
Table 4. Percentage of homeowners policies also with earthquake coverage. 

[Sources A and B. see text.]

Source B

County

Number of Percent of 

Homeowner Homeowners 

Policies With EQ. Coverage

Source A

Number of Percent of

Homeowner Homeowners

Policies With Eg. Coverage

Santa Clara

San Mateo

San Benito

A I ameda

Contra Costa

Mar in

Santa Cruz

Sonoma1

San Francisco

Monterey

Solano1

Napa1

San Joaquin1

Sacramento1

81,314

37,944

1,210

70,210

55,149

13,822

12,502

20,030

21,118

14,873

17,457

6,057

16,380

40,401

34.5

31.5

29.3

27.7

24.8

24.0

23.7

20.7

16.0

15.0

13.7

9.3

5.2

4.1

252,721

120,363

3,657

203,365

160,425

42,030

37,593

...

79,382

...

40,660

17,804

...

31.6

31.8

27.4

27.8

21.3

24.0

22.5

...

26.5

---

14.1

10.7

...

Bounties contiguous to the study area.

and Mission districts of San Francisco are on maps available to the public. As mentioned above, the prevailing type 

of wood frame construction in San Francisco is more vulnerable to earthquake damage than elsewhere in the Loma 

Prieta study area.

The last two counties in table 4 are located in California's Central Valley and have a lower seismicity than the 

other counties. The percentages for these two counties reasonably reflect the public's perception of this lower hazard.

Additional data from several other companies have 

been used to fill voids or to otherwise strengthen the loss 

estimation analyses. These instances are mentioned where 

they occur.

Postal Zip Codes and Distances from Earthquakes

One direction of this study is to develop loss estimation algorithms which are transferable to other regions 

under practical conditions. For loss estimation purposes and 

also for disaster response planning, dwelling data are normally more available on a postal ZIP basis than on other 

geographic bases. Some sources, such as the national census, can be readily converted to a ZIP basis. ZIP boundaries 

may extend beyond city boundaries; as a consequence, the 

area included in a ZIP by its postal name may also include 

nearby small communities. ZIPs usually contain a sufficient 

number of dwelling losses to be statistically significant with 

the distance attenuated loss percentages.

For the Loma Prieta study area, distances were computed to each ZIP's geographic centroid. Locations of geographic centroids are essentially identical to those of 

housing centroids for the usual ZIP, but errors may occur

when large uninhabited areas are included. The term "ZIP 

to fault" distance or "fault distance" is defined as the shortest distance from the surface projection of the earthquake's 

line source to the ZIP's population weighted centroid. An 

exception to this definition is for mobile home parks, where 

in some instances the distance from the line source is that 

from the park rather than from its ZIP centroid.

Figure 4 is a map of ZIPs in the vicinity of the Loma 

Prieta earthquake. The heavy black straight line with the 

diamond in the center has the same meaning as that in 

figure 3. The closed loop about the heavy black line is the 

6 mile probable maximum loss (PML) zone; this will be 

further defined and discussed. ZIP boundaries within the 

Santa Cruz Mountains seem to have been in a state of flux 

at the time of the earthquake, inasmuch as four published 

ZIP maps and atlases were examined and each had different boundaries for ZIP 95030 within the Santa Cruz 

Mountains. Other ZIP boundaries in the mountains also 

had uncertainties, but to a smaller degree. The boundary 

uncertainties do not affect our distance calculations since 

the centroids were determined on a population weighted 

basis. Additionally the uncertain boundaries are in very 

lightly populated areas. Also, for reasons discussed later, 

ZIP 95030 was eliminated from the loss over deductible 

analysis and resulting equations.

Dwelling Losses Before and after Deductible

As has been mentioned before, the detail of the information on individual dwellings found in source B exceeds 

that in source A. Table 5 shows paid loss data from source

B8 Estimation of Earthquake Losses to Housing in California
15' SJ94304

:" *' "\ .f!/*'.f&V'. *' '" ' '*" . .-*' 95131 \

I \ /.'.y'-K/' 94086 t 95054 ;.. .. /...-\

94024 ' » \ >: ^ \ '":. .. '*

94087 *' Q50RO ?.. ^V « ' ,«&

95051

95014 I 95129 .;.;

951304-": 95008 "''\

95128'/. .: \.\ \. 

: ''--".' 95125 .^ \

95136

95070

/ *'* .-./ 95124 \ ^ : " " 

 ' : V* ^ 95123

95032

95120

122°|00'

ZIP POST OFFICE ZIP POST OFFICE

94020

94024

94040

94041

94086

94087

94304

95003

95005

95006

95007

95008

95010

95014

95017

95018

95019

95020

95026

95030

95032

95037

95041

95044

95046

95050

La Honda 

Los Altos 

Mountain View 

Mountain View 

Sunnyvale 

Sunnyvale 

Palo Alto 

Aptos 

Ben Lomond 

Boulder Creek 

Brookdale 

Campbell 

Capitol a 

Cupertino 

Davenport 

Pel ton 

Freedom 

Gilroy 

Holy City 

Los Gatos 

Los Gatos 

Morgan Hill 

Mt. Hermon 

Redwood Estates 

San Martin 

Santa Clara

95051

95054

95060

95062

95064

95065

95066

95070

95073

95076

95110

95112

95116

95117

95118

95120

95123

95124

95125

95126

95128

95129

95130

95131

95133

95136

Santa Clara

Santa Clara

Santa Cruz

Santa Cruz

Univ. California

Santa Cruz

Scotts Valley

Saratoga

Soquel

watsonville

San Jose

San Jose

San Jose

San Jose

San Jose

San Jose ,37;

San Jose 15'

San Jose

San Jose

San Jose

San Jose

San Jose

San Jose

San Jose

San Jose

San Jose

121°145' 

95030 J

95037

 .%.. .... ' ,9504l/ ";

95066 ''

San

Benito 

County

121°145'

Figure 4. Postal ZIPs in epicentral area of 

ZIPs limited to portions of Santa Cruz and 

tain. Map adapted from "ZIP Codes in th 

Economic Research Co., Panorama City,

the Loma Prieta earthquake. See figure 3 for relationships to the topography. 

Santa Clara Counties. ZIP boundaries in the Santa Cruz Mountains are uncer3 San Francisco Bay Area" by permission of the copyright owner, Western 

California. Heavy black line and loop are explained in figure 3.

B for 45 dwellings of the 2,888 insured dwellings in Santa 

Cruz County. Losses include those paid under earthquake 

and/or homeowners policies, under condominium policies,

and under HO tenants (renters) policies. Specifically 

shown is a portion of ZIP 95003, which extends north 

from Monterey Bay into the Santa Cruz Mountains. Aptos

Dwelling and Mobile Home Monetary Losses Du<; to the 1989 Loma Prieta, California, Earthquake, with an Emphasis on Loss Estimation B9
and Rio Del Mar are in this ZIP, as are mountainous rural 

areas. Table 5 dwellings are in Santa Cruz County, where 

the highest percentage of paid losses was found (table 3).

Column 1 is the dwelling's ZIP. Column 2 is year 

built. Columns 3 and 4 are the dollar deductibles (HO for 

homeowners; EQ for earthquake). The "9" in column 5 

indicates that the number of brick masonry chimneys is 

unknown; other numbers indicate number of chimneys. 

Column 6 gives the number of stories H means one and 

a half, and U or blank means unknown; coding available 

includes B for bi-level, I for two and a half, and T for trilevel (none of these shown on this page of table 5). In 

column 7, K is wood shake, W is wood shingle, U is unknown, T is clay tile, and C is concrete tile; blank means 

unknown. Columns 8 and 9 are the amounts ("LIMIT") of 

fire insurance coverage. "EQ Blanket" in column 10 is the 

amount of earthquake insurance coverage; fire insurance 

coverage represents dwelling value, whereas earthquake 

coverage may be written for any amount at $100,000 or 

over for HO (non-tenant) and $10,000 or over for tenant 

and condo. Column 11 is the percentage of insurance to 

value; this allows revision of column 8 values when a 

homeowner insured a dwelling for something less than 

value. Contents limits do not allow this kind of revision. 

Column 18 (next to last column) is the occupancy designation: T for tenant (only contents insured); C for condominium unit owner; and N for non-tenant (home owner).

Table 44 (at end of report) is a summary of loss data 

by ZIP in ZIP-fault distance order for the Loma Prieta 

study area. A negligible number of corrections and deletions was made to the source data, mostly to dwellings 

which were incorrectly coded as to location. ZIPs with 

few insured dwellings are normally ZIPs assigned to post 

office boxes, to governmental entities, or to organizations 

with very high mail uses.

The meanings of table headings for table 5 also apply 

here, with these additions. "Cover" is an insurance term 

for insurance coverage, that is, an insurance policy. 

"CONTS." refers to the contents of the building.

Earthquake losses could be paid under either the 

earthquake policy ("EQ COVER") and/or under the homeowner policy ("HO COVER") owing to policy wording 

and differences in deductibles. ZIP 95030 had the heaviest 

losses because of geologic hazards in the Santa Cruz 

Mountains. Methods for computing the values in columns 

7, 12, 28, 29, and 30 are shown at the bottom of the last 

page of table 44.

The insurance deductible used by source B differed 

considerably from that used by source A companies. Source 

B allowed the insured to purchase a different amount of 

earthquake insurance from that for fire. The amount of earthquake insurance for HO (non-tenant) could be between 

$100,000 (the minimum) and the amount of building and 

contents for fire insurance plus an amount for ALE (additional living expense). For tenants and condo unitowners, a

minimum of $10,000 applies to the earthquake coverage and 

additional limits may be purchased. The earthquake deductible was 10 percent of the amount of earthquake coverage 

and not of the fire coverage and is applied in dollars to the 

total earthquake loss. Claims practice allowed the determination of what portion of the deductible was applied to the 

building, contents, or ALE loss. For example, assume a 

person has a $200,000 dwelling with fire insurance and it 

was insured to full value. Were that person to chose 

$150,000 in earthquake insurance coverage, the earthquake 

deductible would be $15,000. This is 7.5 percent in terms of 

dwelling value. In a few instances, deductibles for Loma 

Prieta dwellings with paid losses became as low as 2 percent 

and 3 percent of building value.

It should be noted in passing that loss figures may be 

compiled somewhat differently by different companies, 

depending upon the adjustment practices. Should a dwelling become a total loss, the order in which a deductible is 

applied to the building, to its contents, and to additional 

living expense may cause one or more of these three loss 

components to be underestimated. This discrepancy in 

methods can cause differences in loss values.

Probable Maximum Loss (PML)

It is intended to use Loma Prieta losses as a basis for 

estimating the probable maximum losses for a probable 

maximum earthquake. This process and its analysis is covered in following sections.

Definition of Probable Maximum Loss (PML)

"Probable maximum loss" (PML) is a term commonly used in California earthquake insurance loss estimation. The California Department of Insurance (1981, p. 

6) defined the geologic aspects of PML in "California 

Earthquake Zoning and Probable Maximum Loss Evaluation Program," as follows:

The probable maximum loss for an individual building is that 

monetary loss expressed in dollars (or as a percentage of insured 

value) under the following conditions:

(a). Located on firm alluvial ground or on equivalent compacted 

man-made fills in a probable maximum loss zone [defined later], and

(b). Subjected only to the vibratory motion from the maximum 

probable earthquake, that is, not astride a fault or in a resulting 

landslide.

The California Department of Insurance has changed 

a portion of its original definition of PML to a loss over 

deductible approach. See Steinbrugge and Algermissen 

(1990) in the sections "Loss Over Deductible Approach" 

(p. A60) and "Applications to Simpler Methods" (p. A61) 

for the basis for the change.

Wood frame dwellings meeting these criteria in the 

probable maximum loss zone (PML zone) are grouped

B10 Estimation of Earthquake Losses to Housing in California
Table 5. Santa Cruz County paid losses (portion of computer hard copy),

[Source B, see text. Shown are 45 out of 2,888 homeowner, condominium, and tenant policies.]

ZIP YEAR 

(1) (2)

95003 84

95003 76

95003 72

95003 78

95003 83

95003 72

95003 65

95003 82

95003 85

95003 80

95003 84

95003 79

95003 53

95003 83

95003 75

95003 87

95003 69

95003 37

95003 86

95003 58

95003 75

95003 88

95003 66

95003 62

95003 55

95003 73

95003 60

95003 65

95003 69

95003 89

95003 60

95003 89

95003 66

95003 75

95003 63

95003 63

95003 74

95003 89

95003 86

95003 80

95003 66

95003 70

95003 75

95003 66

95003 65

DEDUCTIBLE 

HO EQ 

(3) (4)

500

500

250

250

250

250

250

250

500

500

500

1.000

1,000

250

1,000

250

250

1,000

250

500

250

250

250

250

500

250

500

500

250

500

250

250

500

250

250

250

250

500

500

500

500

250

500

500

500

20,000

15,240

10.000

10.000

2,000

11,600

10,000

10.000

20.000

10.000

24,000

10.000

10,000

15.000

10,000

8.600

12.200

35.730

16,500

10,000

10.000

1.000

15.000

10,000

10,000

10,000

10.000

10,000

19.200

30.000

10,000

1,000

16.000

5.000

10.000

10,000

10.000

10,000

10,000

10,000

16.000

10.000

10.000

10.600

12.000

NUMBER 

CHIM. HT. 

(5) (6)

9

0

9

9

9

1

9

0

0

3

1

1

0

1

9

9

9

1

0

1

0

9

0

1

1

1

1

2

1

0

1

9

1

9

1

1

1

1

1

1

1

1

0

1

1

u

2

U

U

u

1

u

1

H

2

2

H

1

2

U

U

U

2

1

1

1

U

2

1

1

1

1

1

1

1

1

U

2

U

1

1

2

2

1

H

H

1

2

1

1

LIMIT

ROOF 

(7)

U

U

U

U

U

K

T

K

U

U

U

K

K

U

K

K

K

K

U

U

W

K

K

C

DWELL. 

(8)

192.200

174.000

88.800

91,400

2.820

123.600

135.500

124.600

214.400

304.400

237,400

219,300

83,200

190,000

283.600

9.370

132,800

360,800

171,200

128.700

118.700

5.000

182.800

102.000

146.000

160.000

92.000

145,000

198,400

350,000

153.600

3.640

202,000

0

101,000

115,000

127.800

213,000

107.000

174,000

160.000

126.000

92,200

113,400

120.000

CONTS. 

(9)

146,650

133,000

74,100

73,550

28.200

95,200

106.625

95,950

171,300

238,300

183,050

166,975

64.900

145.000

215,200

98.700

102.100

273.100

130.900

99.025

94.025

50,000

139,600

79,000

112.000

122,500

71.500

116,250

151,300

277.500

127,700

36,400

161,500

55.000

78.250

88.750

98,350

162.250

85,250

135.500

122,500

97.000

74,150

95,550

92.500

EQ 

BLANKET 

(10)

200.000

152.400

100,000

100.000

20,000

116,000

100,000

100.000

200,000

100,000

240.000

100.000

100.000

150.000

100,000

86,000

122.000

357.300

165,000

100,000

100,000

10.000

150,000

100,000

100.000

100.000

100.000

100,000

192.000

300.000

100.000

10,000

160,000

50,000

100.000

100.000

100,000

100.000

100.000

100,000

160.000

100.000

100,000

106.000

120.000

INS. 

TO 

VALUE 

(11)

100

100

100

100

75

100

99

100

100

100

100

95

95

100

100

100

100

100

100

100

100

95

100

100

100

100

100

100

100

100

95

85

95

100

100

100

100

100

95

100

95

100

100

100

100

LOSS AFTER

DWELL. 

(12)

11,065

0

53,740

7.024

4,248

28

23.960

382

0

11.134

0

22,053

3.343

14,940

43,107

5.061

1.631

52.252

0

9.547

16.768

9.619

16,979

0

54.352

3,804

1,026

1,848

15.009

0

0

3,849

0

0

0

26,965

1.079

0

0

60.196

13,683

6,751

0

6.956

2,488

EQ COVER

CONTS. 

(13)

1.368

0

398

2,985

1,450

755

7.895

853

0

0

0

14,255

0

3.099

9.317

3,229

2,051

24.665

0

0

1,919

381

785

0

1,802

0

0

1.133

6,576

0

0

931

2.018

6.090

0

3,500

1.103

0

0

5,476

8,230

469

0

5,800

4.445

ALE 

(14)

0

0

2,500

0

0

0

0

0

0

0

0

0

0

0

5,000

0

0

0

0

300

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

3.000

0

0

0

0

0

714

0

0

0

DEDUCTIBLE

DWELL. 

(15)

0

2.755

0

0

0

0

0

59

535

0

5.248

0

0

0

0

0

0

0

1,470

0

0

0

0

910

0

0

0

0

0

2.499

207

0

0

0

2,256

0

0

672

525

0

0

0

0

0

0

HO COVER

CONTS. 

(16)

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

100

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

100

0

0

ALE 

(17)

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

OCCUR. 

TYPE 

(18)

N

N

N

N

C

N

N

N

N

N

N

N

N

N

N

C

N

N

N

N

N

C

N

N

N

N

N

N

N

N

N

C

N

T

N

N

N

N

N

N

N

N

N

N

N

FAULT 

DIST. 

(mi.) 

(19)

3.5

3.5

3.5

3.5

3.5

3.5

3.5

3.5

3.5

3.5

3.5

3.5

3.5

3.5

3.5

3.5

3.5

3.5

3.5

3.5

3.5

3.5

3.5

3.5

3.5

3.5

3.5

3.5

3.5

3.5

3.5

3.5

3.5

3.5

3.5

3.5

3.5

3.5

3.5

3.5

3.5

3.5

3.5

3.5

3.5

Dwelling and Mobile Home Monetary Losses Due to the 1989 Loma Prieta, California, Earthquake, with an Emphasis on Loss Estimation B11
together as a class probable maximum loss percentage 

(class PML). The class PML percentage is the aggregate 

loss divided by its aggregate value at zero deductible. The 

word "class" is normally omitted and context indicates its 

inclusion. A percentage PML is determined for a specific 

event such as the Loma Prieta earthquake, and PMLs from 

various earthquakes can be used as the basis for estimating 

the PML for different magnitude earthquakes. The percentage PML is the average within a PML zone, defined 

below.

Definition Of PML Zone

The PML zone (fig. 3) is defined as that area within 6 

miles (10 km) of the linear surface projection of the earthquake's line source of energy (Steinbrugge and Algermissen, 1990, p. A37). One may consider the PML zone to be 

a quantified form of an earthquake's macroseismal region 

or epicentral region. The monetary loss is assumed to be 

uniform throughout the zone and then to decrease beyond 

the zone boundary. This 6 mile (10 km) distance is the 

same as the customary focal depth of California earthquakes. The Loma Prieta focal depth was 17.6 km, deeper 

than customary. The Loma Prieta earthquake allowed the 

testing of this distance limit because loss data were distributed beyond the 6 mile PML zone boundary. The reasonableness of the PML zone model when applied to 

Loma Prieta data will be examined in a following section.

Losses in the Loma Prieta PML Zone

Losses in the PML zone were examined from three 

viewpoints, each having a different objective in mind:

(1) Losses to all buildings, including those damaged 

or destroyed by landsliding, soil liquefaction, 

and other ground displacements. Their aggregate 

losses are unique to the Loma Prieta earthquake 

and are not likely to be transferable to other 

areas for loss estimation purposes.

(2) Losses to all buildings, excluding those where 

ground displacements such as landsliding, soil 

liquefaction, and other ground displacements occurred. Buildings may be on steep hillsides or 

on level land. These losses have the advantage 

of reducing the difficulties associated with region-specific ground displacements. There are 

significant uncertainties with these losses.

(3) Losses to buildings on level or gently sloping 

ground where no geologic hazards are known. 

This excludes hazards which will be later defined in the section after next on geohazards. 

This information has the best potential of the 

three for transferability to other regions where

Table 6. Number of insured dwellings from source B data grouped by 

decade.

[Data comprise insured dwellings, 

with or without earthquake 

coverage.]

Study Area

Age Group 9-County PML Zone

28

18

12

80

153

397

1,043

1,805

2,044

1,180

6,760

Pre-1901

1901-09

1910-19

1920-29

1930-39

1940-49

1950-59

1960-69

1970-79

1980-89

988

1,378

2,238

6,028

10,649

21,416

57,664

60,971

48,952

32,242

242,526

VML, probable maximum loss (defined in text).

site-specific geologic information can be independently included in the loss algorithms.

Losses by Age Groups

Experience has shown that older wood frame dwellings are much more vulnerable to damage than are the more 

modern ones (Steinbrugge and Algermissen, 1990). The dividing year between older and newer dwellings has been 

1940; this has been supported by loss experience from the 

1971 San Fernando and 1983 Coalinga earthquakes. The 

validity and appropriateness of the 1940 dividing year applied to the 1989 Loma Prieta data were re-examined. Postearthquake field observations everywhere in the study area 

confirmed the reasonableness of this division, although the 

year could be changed in some communities.

The need and appropriateness to continue this age separation is diminishing. Table 6 is an age distribution by 

decade of source B dwellings at the time of the earthquake. 

Since then, the number of pre-1940 dwellings has been 

slowly decreasing due to demolition. Some have been 

earthquake strengthened (retrofitted) and now they should 

be considered as being equivalent to post-1939 construction. Much of the 1940-49 construction reflects better construction as a result of the 1933 Long Beach earthquake 

with its resulting building code changes and changes in 

construction practices. Experience from the 1983 Coalinga 

earthquake indicated that it was reasonable to combine the 

1940-49 data with the post-1949 data (Steinbrugge and Algermissen, 1990, table 17). Table 6 shows that the older 

buildings in the study area and also in the PML zone are 

comparatively few in number. Table 7 shows that the numB12 Estimation of Earthquake Losses to Housing in California
Table 7. Homeowner insured dwellings from source B data, with 

or without earthquake coverage.

9-County Study Area

Age Group

Pre-1940 

1940-49 

Post -1949

Number of 

Dwellings

21,281 

21,416 

199,829

Percent 

of Total

8.8 

8.8 

82.4

PML 1 Zone

Number of 

Owe I lings

291 

397 

6,072

Percent 

of Total

4.3 

5.9 

89.8

Table 8. Paid losses to dwellings 

with earthquake coverage grouped 

by decade.

[Excludes earthquake losses paid 

under homeowner policies.]

All ages 242,526 100.0 6,760 100.0

*PML, probable maximum loss (defined in text).

ber of pre-1940 dwellings in the PML zone were fewer on 

a percentage basis than those for the entire study area 4.3 

percent and 8.8 percent, respectively.

Of the 291 pre-1940 buildings in the PML zone, only 

32 had paid insurance losses. These were too few for a 

meaningful PML and loss over deductible analysis. Table 8 

is another viewpoint using paid losses. Although the pre1940 dwelling failures were often of large scale and spectacular, they contributed only 4.7 percent of the total dollar 

loss in the PML zone from the Loma Prieta earthquake. In 

the study area, losses to these older buildings contributed 

8.5 percent to the total.

Because pre-1940 construction will become increasingly less significant over time in loss estimation studies, 

our analysis from this point is primarily directed to post1939 data. It is reasonable for future loss estimation purposes to use the post-1939 PML values for dwellings of 

all ages because aggregate losses will differ little for moderate to large earthquakes in California.

Elimination of Losses Due to Major Geohazards

Topographic contours in figure 3 clearly indicate the 

mountainous terrain of most of the PML zone. Landslides, 

permanent ground displacements, and related geologic effects were common throughout the PML zone. These are 

defined as sites with geohazards.

The definition of geohazards is broadly interpreted to 

include construction sites on steep slopes where differential ground movements may or may not have been observed. For example, a wood frame house on a steeply 

sloping site may be one story at street level. The floor at 

that level is usually anchored to a reinforced concrete 

foundation. The rear, being downside, may have three stories of wood frame construction down to its reinforced 

concrete foundation. The two side walls will slope from 

one story to three stories. The relative structural rigidity of 

these walls from the first floor to the reinforced concrete 

foundations varies; thus, in an earthquake torsional 

stresses within the building can result in wall failures. 

Failure is more likely with weak wall sidings like fiberAge Group

Pre-1901

1901-09

1910-19

1920-29

1930-39

1940-49

1950-59

1960-69

1970-79

1989-89

Paid Loss

9- County

661

373

1,031

2,189

2,575

3,696

10,273

22,505

26,000

14,756

. x$1000

PML 1 Zone

484

87

77

802

562

1,026

4,221

11,443

14,979

8,736

Pre-1940 

Post-1939

80,058

6,829

73,229

42,418

2,012

40,406

VML, probable 

(defined in text).

loss

board, as seen in the 1984 Morgan Hill earthquake. Numerous examples of this torsional problem were also 

observed in the 1992 Landers-Big Bear earthquake (EERI 

Newsletter, Sept. 1992, p. 6). Often it is difficult to determine if differential ground movements or torsion caused 

such a failure, or a combination thereof. Several such suspected Loma Prieta sites with losses have been included as 

geohazard losses.

It is necessary to have commonality among geologic 

data if information for loss estimation purposes is to be 

transferable among geographic areas. Commonality is also 

required by the PML definition because of the phrase "firm 

alluvial ground." This excludes dwellings in geologically 

hazardous areas such as landslide terrain and marshlands.

The method used to eliminate dwellings having losses 

due to geohazards in the Loma Prieta study area was to 

field investigate all buildings within 10 miles of the fault 

with high paid losses. Investigations were further restricted to post-1939 earthquake insured construction and 

to ZIPs having 100 or more earthquake policies. By the 

time of our inspections, repairs had usually been made and 

ground cracks had disappeared, but major losses were apparent when driveways and walkways led to nonexistent 

houses. Evidence was not as clear in the more rural and 

mountainous areas. Within these constraints, 176 high loss 

buildings were found within 10 miles of the fault. Of 

these, 86 buildings were in ZIP 95030; this ZIP is almost 

entirely in the Santa Cruz Mountains, where extensive 

landsliding occurred at many building sites. The remaining 

90 dwellings were scattered among 17 ZIPs; almost all of

Dwelling and Mobile Home Monetary Losses Due to the 1989 Loma Prieta, California, Earthquake, with an Emphasis on Loss Estimation B13
Table 9. Geohazard grades for dwellings in source B data.

[Dwellings are wood frame, ppst-1939 construction. Data limited to ZIPs which 

have 100 or more earthquake insured dwellings: also limited to ZIPs 10 miles or 

less from the fault.]

Geohazards grades:

1. Site or near vicinity examined, generally level.

2. Site or near vicinity examined, slight to moderate slopes.

3. Site or near vicinity examined, steeply sloping with significant to severe 

landsliding potential.

4. House gone due to landslide: remnants existed.

5. House inaccessible (locked gate, road out. and so forth) in an area of 

landslides or having high landslide potential.

ZIP To 

Fault 

ZIP (miles)

95076

95003

95066

95073

95006

95005

95065

95018

950301

95062

95032

95070

95060

95020

93907

95120

95124

95130

2.1

3.5

3.9

4.3

4.7

4.8

5.3

5.5

5.7

7.5

7.6

8.5

8.9

9.6

10.0

10.0

10.0

10.0

Dwellings with:

Eq. 

Insur.

408

466

290

152

197

156

123

152

841

258

565

1,363

482

489

186

1,096

1,096

322

Paid Loss

141

193

111

70

76

59

55

63

380

64

66

83

120

45

11

20

6

18

Dwellings with 

Geohazard Grade 

12345

3

1

0

0

0

0

0

0

3

1

1

2

0

0

0

0

0

1

0

0

0

1

1

0

1

0

1

1

1

0

0

0

0

0

6

3

2

8

5

2

0

4

0

1

1

2

0

0

0

0

0

0

2

0

0

2

0

0

0

0

0

1

1

0

0

0

0

0

4

3

3

5

7

0

3

0

0

0

1

0

0

0

0

0

0

Post Office

Uatsonville

Aptos

Santa Cruz2

Soquel

Boulder Creek

Ben Lomond

Santa Cruz

Felton

Los Gatos

Santa Cruz

Los Gatos

Saratoga

Santa Cruz

Gilroy

Salinas

San Jose

San Jose

San Jose

1-rhis ZIP was not field inspected. 

Includes Scotts Valley.

these 90 (or their general sites) were field inspected. It 

should be noted in table 9 that the number of geohazard 

dwellings in a particular ZIP (columns 5 through 9) is 

small compared to the number of dwellings in that ZIP 

(column 3). Field inspections determined a geohazard 

grade for these dwellings, with grades defined as follows:

Grade 1: Site or near vicinity examined. Generally 

level.

Grade 2: Site or near vicinity examined. Slight to moderate slopes.

Grade 3: Site or near vicinity examined. Steeply sloping sites with significant to severe landsliding 

potential.

Grade 4: House gone due to geohazards, normally landslide. Remnants existed.

Grade 5: House inaccessible (fence across road, road 

out, and so forth) in an area having had landslides or having high landslide potential.

Field inspections indicated that almost all dwellings 

with geohazards grades 4 and 5 (table 9) had major losses

associated with landsliding or land movements. Essentially 

all buildings having grade 3 were also undoubtedly affected by land movement or torsion, but this could not be 

proven in all instances. The four ZIPs at 10 miles from the 

fault (93907, 95120, 95124, 95130) are mostly on nearly 

level land; as might be expected, no large losses occurred. 

Increased distance from the fault was also a major contributing factor to reduction in losses.

Paid losses due to geohazards, including those in ZIP 

95030, amounted to about 27 percent of all paid losses in 

the nine-county study area.

PML and Loss Over Deductible

Loss over deductible data are examined on four 

bases: (1) ZIP basis, (2) PML zone basis, (3) Watsonville 

study area basis, and (4) other California experience. 

PMLs are examined using other California experience. 

The results are PML and loss over deductible data in the 

form of tables, graphs, and equations intended for loss estimation purposes.

Source B earthquake insurance policies allowed, in 

effect, a homeowner to select the deductible. The earthB14 Estimation of Earthquake Losses to Housing in California
quake deductible was 10 percent of the amount of the 

earthquake policy which has a $100,000 minimum. There 

is no required relationship between amount of the earthquake policy and the fire policy. Therefore, building value 

was determined from the fire insurance policy adjusted for 

insurance to value.

A more precise and restrictive "high loss" definition 

of value was used for the PML and loss over deductible 

analyses. Whenever the ratio of structure loss to structure 

value equalled or exceeded 2/3, then this loss "was correlated with its geohazard, if any. The 2/3 amount (0.667) 

was determined by the algorithm:

(EQ paid loss + EQ deductible)

(HO fire insured amount adjusted to value).

For purpose of this study, all dwellings having 2/3 

loss or greater as defined above and a geohazard grade of 

3 or more were deleted from the PML and loss over deductible analysis. Additionally, all dwellings in ZIP 95030, 

with its large number of geohazard losses in the Santa 

Cruz Mountains, were deleted because it became impractical to evaluate the geohazard grade at many sites.

Whenever information on a building's value, deductible, and paid loss is known, the building's loss at any 

deductible greater than the policy deductible can be computed. These and derived information may be summed for 

all buildings in any geographic grouping. Finally, each 

building's loss over deductible can be computed for a 

range of deductibles and then summed by individual ZIPs, 

by PML zone, and by study area as discussed in the following sections.

The methods used to determine replacement value 

vary among insurance companies. The California Department of Insurance conducted a data call in the winter of 

1993 to examine company practices. One conclusion from 

this study was:

There is a large variation in the replacement cost calculation 

methodology among companies. This results in variations as 

much as 50% in replacement cost calculations for the same dwelling. The replacement cost formulas do not..... address the costs of 

hillside construction. (California Department of Insurance, unpublished data, January, 1994).

Where applicable, we considered the reliability of replacement values in our analysis.

Table 10 shows the paid losses and values for dwellings in the PML zone as a function of percent deductible. 

It can be seen that the majority of buildings had deductibles between 5 and 11 percent. It is also evident that determining loss over deductible values are impossible for 0 

and 1 percent deductibles because of the absence of data.

There are several aspects of loss over deductible calculations which are sometimes not clearly understood. As 

shown in table 10, at 5 percent deductible, there were 100 

dwellings of which 53 had paid losses. The loss over deductible at 5 percent deductible is thus the paid losses diTable 10. Paid losses and values as function of percent 

deductible for dwellings in PML zone.

[Data from source B; limited to wood frame, post-1939 

construction and to ZIPs which had 10 or more earthquake 

insured buildings, excluding ZIP 95030. All values and 

losses in millions of dollars.]

Number of Bldgs.

Pet. 

Ded. 1

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

All 

Bldqs.

0

0

1

17

40

100

131

173

273

491

293

131

85

78

49

27

16

13

9

1

5

1,933

Paid 

Loss

0

0

1

9

28

53

72

75

126

204

91

40

30

14

8

9

3

2

1

0

1

767

Paid 

Loss

0.00

0.00

0.03

1.46

1.52

1.89

1.31

1.71

2.35

3.30

1.44

0.36

0.34

0.15

0.18

0.13

0.03

0.02

0.01

0.00

0.00

16.22

Value

All 

Bldgs.

0.00

0.00

0.55

6.88

10.78

20.56

23.18

27.63

39.22

72.39

40.74

14.31

9.86

7.50

5.16

2.85

1.46

0.99

1.03

0.10

0.36

285.53

Paid Loss 

Bldgs.

0.00

0.00

0.55

4.39

7.83

11.17

12.48

12.06

17.92

30.45

11.97

4.32

3.13

1.33

0.61

1.08

0.29

0.12

0.06

0.00

0.10

119.85

Percent deductible is average of earthquake dollar 

deductible in terms of percent of value, plus or minus 

0.5 percent.

vided by the value of all buildings with a 5 percent 

deductible. If one or more of the 40 buildings at 4 percent 

deductible sustained losses which would have exceeded 

the 5 percent deductible, then these losses must be added 

to those stated in the previous sentence. This process is 

continued for all deductibles. Although a person might 

wish to add the deductible to the losses to obtain losses at 

zero deductible, these losses would not include the very 

numerous losses from 1 to 4 percent of value which had 

been excluded by the deductible. This would not produce 

satisfactory loss over deductible information for the lower 

deductibles.

Loss Over Deductible Zip Basis

Table 11 shows the percentage loss over deductible for 

all ZIPs which are not over 10 miles from the fault. All data 

are on wood frame dwellings built after 1939. ZIP 95030 in 

the Santa Cruz Mountains was not included for reasons 

previously discussed. Additionally excluded were all buildings having losses over 2/3 of value and which also had a 

geohazard grade 3 (table 9) or greater. Buildings with lower

Dwelling and Mobile Home Monetary Losses Due to the 1989 Loma Prieta, California, Earthquake, with an Emphasis on Loss Estimation B15
geohazard grades could have large losses which would not 

necessarily be due solely to geohazards. It follows that the 

losses over deductibles are on the high side because all 

geohazard related losses were not removed.

ZIPs in the PML zone are the first eight in table 11 

(Watsonville through Felton). Each has a data distribution 

similar to that shown in table 10. The quality varies with 

the number of buildings and with the amount of the losses.

The aggregate dollar loss over deductible is a constantly decreasing number as the deductible becomes 

greater. In table 11, the 10 percent deductible (at the dotted line) is a reasonable percentage at which the data become well behaved for the 10 to 20 percent range. The 

greater the number of insured buildings (see bottom of 

table), the better the loss over deductible data become.

Our loss model assumes fairly uniform loss over deductible percentages within the PML zone; the actual distribution within the 6 mile PML zone may be seen at the 

10 percent level in table 11. The greatest variation is between Felton ZIP 95018 at 2.72 percent and Ben Lomond

ZIP 95005 at 1.40 percent. These are contiguous ZIPs, in 

mountainous terrain, and with relatively few insured buildings and losses the small amount of data as well as the 

impact of omission/inclusion of one or more large geohazard losses are possible explanations.

Figure 5 provides insight into table 11 by plotting 

percent loss over deductible at 10 percent deductible 

against fault distance. Refer to the dotted orthogonal axes 

intersecting at 6 miles (PML boundary) and 1.0 percent. 

Compare the ZIP data in the upper left hand quadrant with 

those in the lower right hand quadrant; losses over deductible related to fault distances within and beyond the PML 

zone are grouped as expected. The two ZIPs in the upper 

right hand quadrant of figure 5 are in the city of Santa 

Cruz and geographically near those in the upper left hand 

quadrant; the reason for this scatter is not clear.

Figure 6 is a plot of average paid loss in each PML 

ZIP. This graph is easier to understand than figure 5 and has 

less data scatter. If dotted line axes were plotted through 6 

miles and $5,000 loss similar to figure 5, a similar insight

3.0

2.5

2.0

1.5

1.0

0.5

95076 Wat

Watsonvil

sonville

95066 Santa Cruz 

95003 Aptos

le study area

95018 Felton 

95065 Santa Cruz

95073 Soquel

 95006 Boul

95005 Ben Lomond

ler Creek

95062 Santa Cruz

95032 Los Gatos 

95070 S

95060 Santa Cruz

95020 Gilroy 

< 

aratoga J

93907 Salinas 

95120 San Jose 

94124 San Jose 

95130 San Jose

10

DISTANCE FROM FAULT, IN MILES

Figure 5. Percent loss over deductible at 10 percent deductible plotted against distance 

from the fault. See text for discussion. Watsonville study area is defined in section "Loss 

Over Deductible Watsonville Study Area" and in figure 7.

B16 Estimation of Earthquake Losses to Housing in California
Table 11. Percent loss over deductible for dwellings in ZIPs 10 miles or less from the fault as a function of percen

in table 1 0).

n

BL

a:

I.

o

[Data from source B and are limited to wood frame, post-1939 construction; data also limited to ZIPs which have 1

insured dwellings. Excluded are buildings with geohazards 3 through 5 having losses of 2/3 of value or more. 

Hori zonal row of dots explained in text.]

Watson- Santa

ville Aptos Cruz Soquel

Pet. ZIP ZIP ZIP ZIP

Ded. 95076 95003 95066 95073

0

1

2

3

4 6.07 4.54 2.45 3.82 

5 5.82 2.98 1.58 4.74

6 4.53 2.27 1.77 3.96

7 3.23 2.56 2.23 3.60

8 2.41 2.28 1.81 3.05

9 2.60 2.17 1.97 2.58

10.... 2. 47... 1.79... 1.87.... 2. 44.

11 2.14 1.64 1.70 2.13

12 1.99 1.51 1.52 1.93

13 1.76 1.36 1.40 1.73

14 1.59 1.31 1.25 1.63

15 1.49 1.20 1.14 1.50

16 1.36 1.11 1.06 1.39

17 1.26 1.03 0.97 1.29

18 1.16 0.96 0.88 1.18

19 1.08 0.89 0.80 1.08

20 1.00 0.82 0.74 0.98

Fault distance, in miles:

2.1 3.5 3.9 4.3

Number of Eq. insured buildings:

408 466 290 152

Number of buildings with loss over

141 193 111 70

Average building value, x$1000:

160 160 159 157

Average value of paid loss, x$1000

11.94 7.75 8.62 15.53

Boulder

Creek

ZIP

95006

...

4.00

4.62

3.20

2.48

..1.69.

1.47

1.25

1.10

1.08

0.93

0.85

0.76

0.68

0.60

0.53

4.7

197

Ben

Lomond

ZIP

95005

4.93

2.82

3.26

2.26

1.43

..1.40..

1.27

1.25

1.10

0.96

0.90

0.84

0.78

0.73

0.67

0.61

4.8

156

Santa

Cruz

ZIP

95065

8.59

5.76

3.52

3.23

3.63

.2.54.

2.17

1.99

1.76

1.56

1.39

1.24

1.10

0.97

0.89

0.85

5.3

123

Felton

ZIP

95018

...

...

1.16

2.93

2.53

..2.72..

2.87

2.57

2.37

2.24

2.22

2.09

1.95

1.83

1.73

1.64

5.5

152

Santa

Cruz

ZIP

95062

-..

...

...

1.69

2.02

.1.28..

1.21

1.06

0.93

0.94

0.87

0.92

0.86

0.82

0.77

0.73

7.5

258

Los

Gatos

ZIP

95032

1.31

1.16

1.00

0.85

0.68

.0.42.

0.38

0.38

0.32

0.27

0.23

0.21

0.18

0.16

0.14

0.12

7.6

565

Saratoga

ZIP

95070

0.39

0.40

0.30

0.24

0.18

0.13

0.26

..0.18.

0.16

0.14

0.13

0.12

0.11

0.10

0.10

0.09

0.08

0.08

8.5

1,363

Santa

Cruz

ZIP

95060

2.69

1.88

1.98

1.86

1.29

..1.27.

1.14

1.01

0.89

0.80

0.72

0.65

0.59

0.54

0.49

0.46

8.9

482

Gi Iroy

ZIP

95020

1 flA I . DO

0.31

0.42

0.23

0.39

0.31

..0.31.

0.32

0.28

0.36

0.33

0.30

0.27

0.25

0.23

0.21

0.20

9.6

489

San 

Jose 

ZIP 

95130 9

--- 

--- 

--- 

--- 

--- 

.. ---...

--- 

--- 

--- 

--- 

--- 

--- 

--- 

--- 

--- 

10.0 1

322 1

deductible:

76

137

J

6.80

59

133

5.90

55

157

12.03

63

123

6.58

64

120

5.00

66

197

3.43

83

228

1.64

120

151

5.50

45

147

1.84

6 

122 

0.03 0
would develop. Figure 5 is more informative since it includes deductibles and therefore eliminates a variable. The 

Watsonville study area, by itself in the lower left hand 

quadrant in both figures, will be discussed in the next section. Loss attenuation within the PML zone is not evident, 

although one could draw a line or curve through the entire 

10 mile data set.

The variation in loss over deductible amounts among 

ZIPs may be partially attributed to construction: the number 

of stories, type of roof (wood, tile), masonry chimneys (or 

none), interior finishes, and the like. The influence of some 

of these construction components will be discussed later. 

Most probably of greater importance are geophysical factors: fault distance, directionality of seismic waves from 

their source, and building sites susceptible to geohazards.

The effect of geohazards on loss over deductible is 

shown in table 12. The effect on individual ZIPs varies 

from 7 to 52 percent. The reduction is 23 percent in the 

PML zone and is 21 percent in the 10 mile zone. The 

small percentage difference is due to the few losses over 

10 percent beyond the PML zone 45 to 48 buildings, respectively. ZIP 95030 is excluded.

Loss Over Deductible Zone Basis

The information in table 11 is shown in aggregate 

form in columns 3 and 4 of table 13. The dots at 10 percent deductible have the same sense as those in table 11. 

The loss over deductibles in columns 2, 3, and 4 are better 

behaved at lower deductibles than those for individual

ZIPs in table 11 owing to the larger data set of buildings 

and losses. The PML zone values in column 3 appear reasonable beyond the 5 percent deductible (table 10).

The effect of geohazard elimination in the PML zone 

is significant; compare columns 2 and 3 at 10 percent deductible. The effect of distance on loss is also significant; 

compare columns 3 and 4.

The 1983 Coalinga data shown here are for informational purposes and will be discussed below under "Other 

California Experience."

Loss Over Deductible Watsonville Study Area Basis

It has been stated that the elimination of grade 3 and 

higher geohazard buildings with high losses undoubtedly 

discounted an unknown number of losses from buildings 

with lessor or undetected geohazards. This undoubtedly increased the loss over deductible values for ZIPs in table 

11 and for the PML zone in column 3 of table 13. It was 

therefore desirable to examine a test area where a better 

examination of the influence of geohazards on losses 

could be undertaken.

The City of Watsonville and the contiguous portions 

of the community of Freedom to the northwest were chosen for a detailed study (fig. 7). This study area consists of 

a small area surrounded by ZIP 95076 (fig. 4). Watsonville 

is the largest city entirely within the PML zone and also 

the closest large one to the faulting. The study area is 

mostly on level or gently sloping terrain. The principal exception is Struve Slough, where potential geohazards were

$20.000

$15,000

$10,000

$5,000

$0

95076 W

Watsonvllle

itsonville

95003 Aptos *

95006 Boulder < 

95005 Ben

study area

95073 Soquel

95065 Santa Cruz

95066 Santa Cruz

95018 F 

>eek 

.omond 

>1ton 

95062 Santa Cruz

95032 Los Gatos

95070 S

95060 Santa Cruz

95020 Gilroy

 V

aratoga I

93907 Sallnas 

95120 San Jose 

94124 San Jose 

95130 San Jose

4 6 

DISTANCE FROM FAULT, IN MILES

10

Figure 6. Average paid building loss per earthquake insured building plotted against distance 

from fault. See text for discussion.

B18 Estimation of Earthquake Losses to Housing in California
Table 13. Percentage loss over deductib

1983 Coalinga earthquakes as a function of 

Q.

i

CT

ffi"

I

n

O

I

[Data limited to wood frame, post-1939 con

to ZIPs which had 100 or more earthqua

excluded. Horizontal row of dots explain

o

Sa

n

SL 

f

.a 

I

Table 12. Effect of geohazards on loss over deductible in PML zone ZIPs.

[Data from source B. All buildings are within 6 miles from surface projection of 

the line source of faulting. Limited to wood frame post-1939 construction; also 

limited to ZIPs which have 100 or more earthquake insured dwellings.]

Percent Loss over

Deductible at

ZIP

95076

95003

95066

95073

95006

95005

95065

95018

Distance

To Fault

(miles)

2.1

3.5

3.9

4.3

4.7

4.8

5.3

5.5

PML zone - -

10 mi zone 

10 Pet.

All

Building

Sites

2.91

2.04

2.10

4.13

3.54

1.95

2.73

3.23

2.66

0.78

Deductible

Excl udi ng

Geohazard

Sites1

2.47

1.79

1.87

2.44

1.69

1.40

2.54

2.72

2.06

0.62

Number of

Excluding

Geohazard

Sites1

408

466

290

152

197

156

123

152

1.944

8.503

Buildings

Only at

Geohazard

Sites1

7

6

3

9

13

2

2

3

45

48

Reduction Due

To Geohazard

Elimination.

(Pet.)

15

12

11

41

52

28

7

16

23

21

"Geohazard grades 3 and higher and having 2/3 building loss or greater.

1989 Loma Prieta Earth

Excluding Geohazard G

Pet.

Ded.

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

Geohazards

Included.

0-6 Miles

From Fault

(PML Zone)

...

...

3.41

3.17

3.15

3.15

.... 3.12 ....

2.90

2.75

2.66

2.52

2.37

2.24

2.10

1.98

1.86

1.75

3 Through

2/3 Loss

0-6 Miles

From Fault

(PML Zone)

...

...

3.11

2.91

2.48

2.35

.... 2.06 ...

1.86

1.70

1.53

1.41

1.31

1.20

1.11

1.02

0.94

0.87

5 and Hav

or Great

0-10 M

From F

...

1.15

0.90

0.82

0.74

0.74

.... 0.62 

0.57

0.52

0.47

0.43

0.40

0.37

0.34

0.31

0.29

0.27

Number of Eq. insured buildings:

1.989 1.944 8.503 

Number of buildings with paid losses:

813 768 1.235 

Average value of buildings. x$1000:

147 147 167

*Steinbrugge and Algermissen. table 17. 1

post-1939.
Figure 7. Watsonville study area and Watsonville city limits. Solid triangles are locations of mobile home parks; 

park numbers are identified in table 26. Open circles are structures outside of the central business district posted 

as hazardous after the earthquake.

B20 Estimation of Earthquake Losses to Housing in California
found on hillsides and bottomland. This area has been developed in recent years, and most structures were expected 

to have had some geotechnical advice on foundations.

The study area is compact, about 3.5 miles long by 

1.5 miles wide. The surface projection of the modeled 

earthquake's line source of seismic energy is shown in figure 7 (see also figs. 2 and 3). The centroid of all dwellings 

in the study area is about 2.5 miles from the surface projection of the line source. The quality of the dwelling distances from this line source must be understood in the 

limitations of the fault model.

Most housing in the study area is of post-1939 construction. The 1940 census states 2,829 one to four family units in 

Watsonville city; the 1990 census states 7,371. This represents over 250 percent growth due to post-1939 construction.

The open circles in figure 7 represent structures posted 

by inspectors immediately after the earthquake as "unsafe" 

based on the Applied Technology Council Field Manual 

(1989). The open circles were plotted from an unpublished 

City of Watsonville manuscript map which summarized the 

inspectors' postings. We excluded postings in the central 

business district and at several large industrial structures. 

As a result, the open circles normally represent wood frame 

dwellings when not located on the main thoroughfares 

named in figure 7. Open circles along these thoroughfares 

can be mercantile buildings of other than wood frame construction as well as wood frame dwellings. The "unsafe" 

structures were almost always of pre-1940 construction. 

City hall maps showing land annexations through 1930 indicated that about 75 percent of the open circle structures 

fell within the original city limits and these annexations. By 

strong contrast, the modern wood frame dwellings in the 

southeast section of the city had no posted "unsafe" dwellings. Many of these dwellings had concrete first floor slabs 

on grade and therefore did not have cripple wood studs 

supporting the first floor. Soil conditions in this southeastern section of Watsonville were soft alluvial materials 

appearing to be similar to those where high density damage 

was noted. Another possible soil indicator is the mapped 

100 year flood limit, which may be roughly described as 

somewhat south of West Beach Street on fig. 7 and its 

northeasterly extension to the city limits.

The other newer areas of Watsonville to the northwest 

are on higher ground and construction is newer. Here 

posted "unsafe" buildings were few.

Available evidence indicates that dwelling age was 

the principal criteria for differences in dwelling damage 

and loss patterns.

In table 14, the loss over deductible at 10 percent deductible for the Watsonville study area may be compared 

using information from tables 11 and 12. Field inspections 

to identify geohazard sites were made of the post-1939 

dwellings in the hill areas, including those around Struve 

Slough (fig. 7). The highest predeductible loss was 43.5

Table 14. Loss over deductible comparisons at 10 percent deductible.

Loss Over Deductible, in Percent

Watsonville study area 0.91

Watsonville ZIP 95076 2.47

PML zone 2.06

percent, with all others being substantially less. Some 

losses may have been associated with cuts and fills beneath dwellings, but no sites exceeded geohazard grade 2. 

The study area is surrounded by Watsonville ZIP 95076 

with higher losses. Construction practices and quality were 

not reasonable explanations for the large differences. Seismic explanations will be later discussed in "PMLs and 

Equations for Loss Over Deductible."

Loss Over Deductible Other California Experience

The major importance of other California experience 

is that it provides loss over deductible information down 

to zero deductible, which is not available for Loma Prieta.

Table 13 information on the 1983 Coalinga earthquake is from table 17 of Steinbrugge and Algermissen 

(1990), revised to combine 1940-49 construction with that 

for post-1949 construction. This revision was for data 

compatibility purposes.

All further references to tables, figures, and curves in 

this section are to Steinbrugge and Algermissen (1990), 

except where otherwise stated. Information from their 

table 17 is shown graphically as curve 3 in their figure 4. 

"Curve 3 in figure 4 was considered to be the most useful 

for loss over deductible applications" (p. A42). Fortunately, the data source for this curve is the same as that for 

Loma Prieta source B, thereby eliminating most inconsistencies among insurance company loss adjusting practices.

We re-examined the choice of curve 3 among those 

shown in their figure 4. The following comparisons are 

made at zero loss over deductible for "post-49" buildings 

with "wood or concrete floors." The 6.60 percent for curve 

4 compared to 4.29 percent for curve 3 is due to the 

changes in building values since all other data were the 

same. Building values for curve 4 were determined by two 

local realtors working independently. They determined average pre-earthquake market values on a city block-byblock basis, or by a group of blocks in some instances. 

The paid insurance losses are more realistic than the realtors' estimates based on groups of houses.

Curve 2 at 8.78 percent is the highest of the three for 

Coalinga. Half of this increase from curve 3 of 4.29 to 

8.78 percent may be due to differences in building valuation methods discussed in the previous paragraph. The 

other half may be due to uncertainties in the numerical

Dwelling and Mobile Home Monetary Losses Due to the 1989 Loma Prieta, California, Earthquake, with an Emphasis on Loss Estimation B21
assignments to damage factors and to degrees of damage 

(Steinbrugge, Fowkes, and others, 1990, p. 373, under 

"Loss (Damage) Ratio"). In favor of curve 2 is its larger 

data base of 530 dwellings compared to 102 dwellings 

used for curve 3. On balance, the smaller amount of accurate insurance data outweighs the authors' larger data base 

of damage factors which were combinations of loss experience and judgment.

Curve 1 San Fernando 8.02 percent loss deficiencies 

are similar to those for curve 2 regarding numerical assignments to damage factors; the 8.02 percent perhaps 

should be reduced by 1 or 2 percent. A judgmental change 

of 1 or 2 percent may seem small on an individual dwelling basis, but this is certainly not true for aggregate loss 

estimations; see their Appendix "Sensitivity: Loss Over 

Deductible vs. Dwelling PML Changes." See also Steinbrugge and Algermissen (1990, p. A35), "Uncertainties 

Concerning Degrees of Damage."

We continue to judge curve 3 to be the best of those 

from previous earthquakes.

PMLS and Equations for Loss Over Deductible

Since the Loma Prieta data did not include loss information in meaningful amounts at low deductibles, Coalinga's curve 3 (Steinbrugge and Algermissen, 1990, fig. 

4) was examined as the model for the shape of the loss 

over deductible curve from 0 to 20 percent for Loma Prieta data. A comparison of Loma Prieta and Coalinga loss 

over deductible curves is shown in figure 8. The data for 

each earthquake were normalized to 1.00 at 10 percent deductible see the open circle at this coordinate. Source 

data for this normalization were derived from tables 11 

and 12. The solid curve in figure 8 is that for normalized 

Coalinga curve 3 data. The solid circles form a curve for 

the 1989 Loma Prieta PML zone. In the latter case, each 

dot is a computed value. A curve based on these dots correlates well from 10 to 20 percent. Below 10 percent, this 

curve deviates, owing to the reduced quantity of data. Not 

shown are similar curves for each ZIP in the PML zone; 

these were centered about the dotted line. The range of the 

curves for these eight ZIPs is shown in figure 8 at the 20 

percent deductible.

The 1983 Coalinga curve 3 was the model accepted 

for extending the Loma Prieta data to zero deductible. The 

three objectives described at the beginning of "Losses in 

the Loma Prieta PML Zone" are now considered. Equations 1, 2, and 3 and their development which follows are 

for the Loma Prieta earthquake: (1) Watsonville study 

area, (2) PML zone excluding major geohazards, and (3) 

PML zone including all geohazards.

The Watsonville study area data were not shown on 

figure 8 since they mostly overlaid the Coalinga curve. 

Figure 9 is an expansion of a portion of figure 8 to include 

the Watsonville study area. The logarithmic equation for

the normalized Watsonville study area curve shown in 

figure 9 is:

LD -7.165841 e-°' 188469D 

where

LD = percent loss over deductible, and 

D = deductible in percent.

This equation is based on the normalized Coalinga curve 3 

from 0 to 10 percent and normalized Watsonville study 

area from 10 to 20 percent. We chose to eliminate the normalization by multiplying the equation by 0.91 (percent 

loss over deductible at 10 percent deductible), which is the

>£° K 3

£§

cc. 

o

Normalized at 

10* deductible

ac.

1

0 5 10 15 20 

DEDUCTIBLE, IN PERCENT

Figure 8. Loma Prieta and Coalinga loss over deductible data with each normalized at 10 percent 

deductible. Also shown is the range of normalized 

loss over deductible data for all ZIPs in the PML 

zone at 20 percent deductible.

B22 Estimation of Earthquake Losses to Housing in California
same number used in normalizing (table 13, column 5). 

The equation for the Watsonville study area becomes

LD = 6.520915 e-°' 188469D (1)

The PML is 6.5 percent by substituting zero for D; it is 

for post-1939 wood frame construction. The quality of the 

PML relies on the assumption that Coalinga curve 3 can 

be validly extended to zero deductible. A caveat lies in the 

small size of the data sample compared to that for the entire PML zone. In its favor is that geohazards are not a 

factor.

Equation 2 is the loss over deductible for the PML 

zone excluding identified geohazard sites 3 through 5 and 

having losses equal to or greater than 2/3. (Subsequent examination showed that the omission of the 2/3 criteria has

CO

O

UJ Q 

O UJ

LU

Q. hUJ Q-

_l

CD i I 

i i

h- hO < 

^

Q O 

UJ O 

Q 

T-H

C£

UJ O 

> hO

O

UO UJ 

GO M 

O M

Normalized at 

at 10* deductible

5 10 15 20 

DEDUCTIBLE, IN PERCENT

Figure 9. Expansion of a portion of figure 8 including 

the Watsonville study area. The Watsonville study area 

data essentially overlaid the Coalinga curve in figure 8. 

The solid circles are for the Loma Prieta PML zone. The 

open circles are for the Watsonville study area.

little effect on the results from equation 2.) The equation 

was developed from the data for normalized Coalinga 

curve 3 from 0 to 10 percent and from the normalized 

PML zone data for 10 to 20 percent (table 13). Using the 

normalization factor of 2.06 from column 3 in table 13, 

the loss over the deductible for the PML zone excluding 

geohazards becomes

LD = 12.38043 e

.-0.148801 D (2)

The correlation between the PML zone data and Coalinga 

curve 3 in figure 9 is not as good as that for the Watsonville study area data and that for Coalinga. It is probable 

that the quality of the 12.4 percent PML from equation 2 

is also not as good.

Equation 3 is for loss over deductible when geohazards are included. Also included are dwellings in ZIP 

95030, which was not part of the two previous equations. 

Utilizing the normalization factor of 3.12 in a manner similar to before; the loss over deductible for the PML zone 

including geohazards becomes

LD = 17.464163 e-°' 133153D (3)

The PML is 17.5 percent from equation 3. This PML can 

be partially verified by determining its lower limit when 

dividing all paid losses plus their deductibles by the value 

of all dwellings; this results in 15.6 percent. This appears 

to be a reasonable value.

Equations 1, 2, and 3 have the following meanings 

for the Loma Prieta PML zone. Equation 1 applies to 

buildings in large areas of level and gently sloping firm 

alluvial soils at distances from mountains. Equation 2 applies to buildings in mountainous terrain and steeply sloping hillsides where landsliding and other geohazards do 

not damage housing or are not included. Equation 3 is 

specific for the Loma Prieta earthquake. Damage in this 

earthquake from ground displacements such as landslides 

was minimal owing to several years of drought. This same 

earthquake after several years of unseasonably wet 

weather would have resulted in greater losses, and equation 3 would thus not be representative.

A comparison between Coalinga curve 3 and the Watsonville study area shows no apparent inconsistencies. The 

PML increases with magnitude as expected:

PML Percent Magnitude

Coalinga curve 3 

Watsonville study area

4.61 

6.52

6.7 

7.1

The Coalinga 4.61 percent PML is from table 13, last 

column.

As a general observation, loss estimation is almost always weak for light damage from 0 to 5 percent of value. 

For example, at what amount of wall and ceiling cracking 

should the entire room be repainted instead of just matching the color and repainting the patch? Was the room

Dwelling and Mobile Home Monetary Losses Due to the 1989 Loma Prieta, California, Earthquake, with an Emphasis on Loss Estimation B23
badly in need of repainting before the event and if so, 

should its depreciated value be considered? Parallels exist 

with a new or old automobile receiving a small dent of 

unknown origin in the case of no deductible. The amount 

of the loss as viewed by the owner is often based on who 

is going to pay the loss. Practices differ among insurance 

companies with respect to dwellings, but often depreciated 

value is not considered for repainting purposes.

Size of the PML Zone

Loma Prieta Earthquake

As seen from figures 5 and 6, the 6-mile limit to the 

PML zone for the Loma Prieta event is a reasonable value. 

Guidelines for damage attenuation within the PML zone 

are difficult to ascertain because of ambiguous data. For 

the present it remains reasonable to use a simplistic average value for the PML zone.

Smaller Magnitude Earthquakes

Studies of instrumental data (Cloud and Perez, 1967) 

from the 1966 Parkfield, California, earthquake provide insights into the PML zone boundary. The earthquake's 

magnitude was about 5.5, and surface faulting was observed. Five accelerograms were obtained within 10 miles 

of the trace of the San Andreas fault. Cloud and Perez 

(1967, fig. 10) suggested no reduction in the acceleration 

from the observed fault trace to 3.3 miles from the trace 

and comparatively little reduction at 5.7 miles. This is a 

rural area having only widely scattered dwellings, and no 

quantified dwelling losses are known. Somewhat surprisingly, the 5.7-mile distance agrees well with the PML 

boundary but by no means substantiates it as a universal 

value.

Another insight from the Parkfield earthquake is by 

Housner and Trifunac (1967):

Integrated velocities and displacements show that near the fault at 

Cholame the surface motion exhibited a transient horizontal displacement pulse of approximately ten inches amplitude and one 

and one-half seconds duration, normal to the fault. Although 50 

per cent of g ground acceleration was recorded at the fault, the 

ground motion attenuated rapidly with distance and at ten miles 

from the fault the maximum acceleration was reduced to onetenth of its near-fault value..... (from paper's abstract)

The Parkfield earthquake was unusual in its pulselike 

shock and was quite different from the Loma Prieta event 

in this respect. All earthquakes examined in this study 

were different from each other in one or more respects, 

and this variability will probably be the future norm.

Magnitude 5 is usually near the threshold for significant 

monetary losses, admitting that small losses do occur in 

smaller earthquakes. Small magnitude earthquakes may be 

considered as a point source rather than as a line source, in

which case the PML zone is bounded by a 6-mile- radius 

circle. Losses from earthquakes of magnitude 5 to 5.5 are 

usually confined to areas much smaller than this circular 

PML zone; aggregate losses are small.

The 1969 Santa Rosa, California, 5.6 and 5.7 magnitude earthquakes, were separated in time by somewhat 

more than an hour and are examples of circular PMLs. 

Generalized dwelling losses and their geographic distribution were mapped (Steinbrugge, 1970, fig. 18). The higher 

losses were within a 1 mile radius of the center of these 

losses. Dollar losses were estimated at $1,370,000 (1969 

dollars) for a city with a population of then 50,000. Dwelling damage was predominately to older houses, and figure 

18 overstates the post-1939 losses in the city of Santa 

Rosa. It has been suggested that damage was intensified 

by local geologic conditions (Steinbrugge, 1970, p. 52).

The 1957 San Francisco (Daly City), California, 

earthquake is a second example (Steinbrugge and others, 

1959). Dwelling damage in this magnitude 5.3 shock was 

typically considerably less than 5 percent, and only in isolated cases did it exceed 5 percent. Houses were constructed shortly before earthquake, and some were still 

under construction. The majority of the dwelling damage 

was confined to sites along a high bluff area about \Yi 

miles long and less than half a mile wide (Steinbrugge and 

others, 1959, fig. 1). There were examples of permanent 

ground displacement in the form of buckled concrete sidewalks and street curbs. For this earthquake, the 6 mile 

PML zone is clearly too large. Damage was accentuated 

by slumping of the bluff. Landsliding occurred again to 

the same bluff in the 1989 Loma Prieta earthquake.

A 6-mile PML zone is too large for most magnitude 5 

to 5.5 earthquakes because dwelling damage, especially on 

firm ground, is confined to a relatively small area. This 

can be simplistically taken into account by using or estimating total dwelling losses from events such as the two 

above examples, then dividing each respective total losses 

by its estimated total dwelling values. Although crude, 

such estimated values are better than those previously determined by extrapolation from larger earthquakes.

1906 San Francisco Earthquake

We consider the maximum credible magnitude earthquake for practical loss estimation purposes to be Ms 8.25 

for the San Andreas fault in the San Francisco Bay region 

and also in southern California. No reliable contemporary 

quantified monetary dwelling loss estimates exist for this 

magnitude (Lawson, 1908). Relevant quantified contemporary information was summarized in Steinbrugge and Algermissen (1990, p. A37/A38):

Only the 1906 San Francisco earthquake has usable loss experience for wood frame dwellings on firm soil in the near vicinity of 

a great earthquake. Over 1,000 houses were examined immediately after that earthquake in the cities from Belmont to Redwood

B24 Estimation of Earthquake Losses to Housing in California
City. All houses were within 1 to 4 miles from the San Andreas 

fault. Damage information is found in Lawson (1908), beginning 

on page 354 of volume I, part II.

Some comparisons between 1906 San Francisco and 1983 Coalinga are of interest. In 1906, the dwelling foundations were unreinforced brick, unreinforced concrete, or wood. Foundation 

anchorage generally did not exist by today's standards. Of 842 

houses, 190 moved on their foundations, or 23% moved. In Coalinga in 1983, 11% of all houses moved a measurable amount; 

24% of all pre-1940 houses also moved a measurable amount 

(Steinbrugge and others, 1990). Interestingly, the older Coalinga 

dwellings shifted in percentage terms as much as did the 1906 

example. Admittedly, wood frame dwelling construction, including foundations, were different.

Brick chimneys were not reinforced in 1906. Of 1,097 brick 

chimneys examined, 88% fell. In Coalinga, 130 pre-1949 chimneys had at least moderate damage out of 158, or 82%. Again, the 

comparison is of interest since damage percentages are similar.

The 1989 Loma Prieta data did not have unreinforced 

brick masonry chimney information to allow comparisons 

with the 1906 San Francisco experience.

Photographs of 1906 San Francisco surface faulting 

showing wood frame structures rarely revealed severe 

damage for structures not astride ground rupture. See, for 

examples, Lawson (1908), v.l, part 1, plates 32C, 37A, 

38D, 45B, 46B, 49A, and 52B. In no way was there total 

damage near the 1906 faulting.

Quantified loss information for the City of San Francisco after the 1906 earthquake is not available. Intensities 

and surficial geology on pages 17 and 19 in Lawson (atlas) are the best contemporary descriptions of damage to 

all classes of structures. Excluding the geohazard areas 

and the burned area (map 20), intensity D predominates. 

This intensity with respect to wood frame dwellings was 

defined in Lawson (v. 1, p. 225) as "comprises general but 

not universal fall of chimneys; .... a few isolated cases of 

lurching or listing of frame buildings built upon weak underpinning structures." Many photographs taken during 

and immediately after the ensuing fire bear out this observation; one may examine the photo collection at the Earthquake Engineering Research Center, Univ. of California, 

Berkeley.

Freeman (p. 282) concluded:

At San Francisco, not long after the quake and fire of 1906, the 

writer spent a week or more in a careful study of the ruins, and 

was again impressed with the number of buildings that had successfully resisted the earthquake shock, both inside and outside 

the limits of the conflagration. He found there was a lot to be 

learned about the general absence of serious earthquake effects 

west of Van Ness Avenue where the conflagration had not extended, and in the large cities across the bay.

Wood frame dwelling construction was the principal type 

west of Van Ness Avenue. This avenue is between 7 to 8 

miles from the San Andreas fault.

In summary, the 6 mile PML zone is reasonable for 

moderate earthquakes based on current knowledge. It has 

limitations when applied to small magnitude earthquakes,

but errors in aggregate dwelling losses for these small 

shaken areas are normally not significant for California loss 

estimation purposes compared to those from major shocks. 

As a postscript, a repeat of the 1933 Long Beach 

earthquake on the San Andreas fault in the near vicinity of 

San Francisco would not cause as much damage as its repeat in the Los Angeles basin. This is because the San 

Andreas fault is partly offshore or in lightly populated 

areas while the opposite tends to be true for Long Beach.

Estimation of Loss Over Deductible and 

PMLs for Other Magnitudes

Post-1939 Construction

The model for loss over deductible in the PML zone 

varying as a function of magnitude has these broadly 

based assumptions:

(1) The amount of seismic energy released per unit 

length of the line source is uniform for the entire 

length of the rupture.

(2) The characteristics of energy release are sufficiently similar among earthquakes and are uniform despite differing geologic environments at 

depth.

(3) The short period components of ground motion 

are similar among earthquakes at similar distances from the energy release, providing that surficial geologic environments are similar.

(4) The 6 mile PML zone is reasonable for magnitudes greater than that for Loma Prieta.

The Loma Prieta subsurface rupture length was 40 kilometers (25 miles). A magnitude 8.25 earthquake such as 

a repeat of the 1906 San Francisco earthquake would 

likely cause 250 to 300 miles of faulting with an assumed 

uniform energy release along the entire length of the faulting. Should the earthquake be very great, such as the 1964 

Alaskan earthquake, the duration of principally long period motions at distant sites may be in terms of minutes 

(Steinbrugge and others, 1967, v. 2, part A, p. 13, under 

"Duration of Shaking"). The shaking duration will increase damage. However in both of these examples, most 

of the energy would originate many miles away from any 

site near the fault and would be dominated at the site by 

long period motions. These long period motions would 

contribute very little to additional damage to dwellings at 

distant sites near the fault. This is not true at geohazard 

sites such as those with liquefiable soils.

Including magnitude as a variable in equation 1 is 

based on these continuing assumptions:

(5) Magnitude 5 approaches the threshold of damage and loss, wherein some dwelling damage 

can be expected.

Dwelling and Mobile Home Monetary Losses Due to the 1989 Loma Prieta, California, Earthquake, with an Emphasis on Loss Estimation B25
(6) A linear relationship is reasonable for a first approximation between losses over deductibles and 

magnitudes.

(7) The PML for short period structures such as 

wood frame dwellings does not significantly increase beyond magnitude 7.75. The rupture 

length and the area of the PML zone increases 

with increased magnitude, the aggregate losses 

increase, but not the percent PML beyond 7.75. 

The upper limit is user-selectable to 8.5 for the 

purposes of the equations which follow.

Equations 1, 2, and 3 are appropriate only for Loma 

Prieta since the influence of Coalinga curve 3 was limited 

to the extrapolation of data from 10 to 0 percent. Equations applicable to other earthquakes must include Coalinga as well as Loma Prieta. Equation 4 is for Coalinga 

data:

LD = 4.110062 e-°- 188686 D (4)

As might be expected, the exponent differs very little from 

that of equation 1. The PMLs differ since the magnitudes 

are different. It follows that curves with different magnitudes are offset by a constant determined by the ratio of 

the PMLs. For example, using equations 1 and 4, the offset ratio is 4.110062 divided by 6.520915, or 0.630. The 

visual effect of differing magnitudes may be seen in figure 

10, discussed below and using equation 7.

Giving equal weight to both earthquakes, an averaged 

equation which locates its curve midway between the Watsonville study area and Coalinga curves becomes:

LD = 5.315489 e-°- 188469D (5)

applicable for magnitude 6.9, midway between the other 

earthquake magnitudes. The Watsonville exponent was 

chosen.

Curves for magnitudes smaller than 6.9 are based on 

a linear extrapolation to magnitude 5, which is the threshold of building damage. The threshold loss at magnitude 5 

for California earthquakes is usually concentrated in a 

small area which is far smaller than its PML zone. As a 

result, the percentage loss over deductible is small for the 

PML zone. In the 1969 Santa Rosa earthquakes (magnitudes of 5.6 and 5.7), the damage was concentrated in 

about 3 percent of its PML zone (Steinbrugge, 1970, fig. 

8). The 1957 Daly City (San Francisco) earthquake had 

similar results for its magnitude 5.3 earthquake (Steinbrugge and others, 1959). The threshold PML has been 

conservatively estimated at 0.5 percent.

A linear relationship is next determined between magnitude and loss over deductible at zero deductible (PML). 

The minimum value is 0.5 percent loss over deductible at 

zero deductible; the maximum value is the PML of 5.315 

percent from equation 5. The relationship is:

where M = magnitude.

Replacing the PML value in equation 5 by equation 6, the 

variable deductible, magnitude, and uncertainty factor become:

LD = [2.534468 (M - 5) + 0.5] e~°- 188469 D x F (7)

where F = user-selected uncertainty factor, and where LD 

may be limited at magnitude 7.75 at the user's option.

An "uncertainty factor" (F) was introduced in equation 7. The equations for loss estimation purposes when 

applied for loss estimation purposes within California 

must be tempered by the many limitations which already

PML = 2.534468 (M - 5) + 0.5 (6)

4 8 12 16 

DEDUCTIBLE, IN PERCENT

Figure 10. Loss over deductible for magnitudes 5 

(threshold of building damage); magnitude 6.9 (equation 

5, basis for equation 7); 7.75 (reasonable upper limit), 

and 8.25 (1906 San Francisco with no upper limit). 

Curves from equation 7 with uncertainty factor of 1.0.

B26 Estimation of Earthquake Losses to Housing in California
Table 15. Percentage loss over deductible as a function of percent deductible for varying earthquake magnitudes. 

[Uncertainty factor = 1. Applicable for post-1939 wood frame dwelling in California. Based on equation 7.]

Percent 

Deductible

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

Magnitude

5.00

0.50

0.41

0.34

0.28

0.24

0.19

0.16

0.13

0.11

0.09

0.08

0.06

0.05

0.04

0.04

0.03

0.02

0.02

0.02

0.01

0.01

5.25

1.13

0.94

0.78

0.64

0.53

0.44

0.37

0.30

0.25

0.21

0.17

0.14

0.12

0.10

0.08

0.07

0.06

0.05

0.04

0.03

0.03

5.50

1.77

1.46

1.21

1.00

0.83

0.69

0.57

0.47

0.39

0.32

0.27

0.22

0.18

0.15

0.13

0.10

0.09

0.07

0.06

0.05

0.04

5.75

2.40

1.99

1.65

1.36

1.13

0.93

0.77

0.64

0.53

0.44

0.36

0.30

0.25

0.21

0.17

0.14

0.12

0.10

0.08

0.07

0.06

6.00

3.03

2.51

2.08

1.72

1.43

1.18

0.98

0.81

0.67

0.56

0.46

0.38

0.32

0.26

0.22

0.18

0.15

0.12

0.10

0.08

0.07

6.25

3.67

3.04

2.52

2.08

1.73

1.43

1.18

0.98

0.81

0.67

0.56

0.46

0.38

0.32

0.26

0.22

0.18

0.15

0.12

0.10

0.08

6.50

4.30

3.56

2.95

2.44

2.02

1.68

1.39

1.15

0.95

0.79

0.65

0.54

0.45

0.37

0.31

0.25

0.21

0.17

0.14

0.12

0.10

6.75

4.94

4.09

3.39

2.80

2.32

1.92

1.59

1.32

1.09

0.91

0.75

0.62

0.51

0.43

0.35

0.29

0.24

0.20

0.17

0.14

0.11

7.00

5.57

4.61

3.82

3.16

2.62

2.17

1.80

1.49

1.23

1.02

0.85

0.70

0.58

0.48

0.40

0.33

0.27

0.23

0.19

0.16

0.13

7.25

6.20

5.14

4.25

3.52

2.92

2.42

2.00

1.66

1.37

1.14

0.94

0.78

0.65

0.54

0.44

0.37

0.30

0.25

0.21

0.17

0.14

7.50

6.84

5.66

4.69

3.88

3.22

2.66

2.21

1.83

1.51

1.25

1.04

0.86

0.71

0.59

0.49

0.40

0.34

0.28

0.23

0.19

0.16

7.75

7.47

6.19

5.12

4.24

3.51

2.91

2.41

2.00

1.65

1.37

1.13

0.94

0.78

0.64

0.53

0.44

0.37

0.30

0.25

0.21

0.17

8.00

8.10

6.71

5.56

4.60

3.81

3.16

2.62

2.17

1.79

1.49

1.23

1.02

0.84

0.70

0.58

0.48

0.40

0.33

0.27

0.23

0.19

8.25

8.74

7.24

5.99

4.96

4.11

3.40

2.82

2.34

1.93

1.60

1.33

1.10

0.91

0.75

0.62

0.52

0.43

0.35

0.29

0.24

0.20

have been discussed. This factor may be viewed as being 

similar to the factor of safety found in building and airplane design, in fused electric systems, and the like. It differs in that this uncertainty factor involves only economic 

loss and does not involve life loss and injury. As a consequence, users have a wide latitude in the selection of an 

uncertainty factor. They are urged to examine the model 

and the data and to select an uncertainty factor to suit their 

need and their comfort level.

Figure 10 is a graphical representation of equation 7 

with an uncertainty factor (F) equal to 1. Curves are 

shown for: magnitude 5, threshold of damage; magnitude 

6.9, average of Watsonville study area and Coalinga; magnitude 7.75, optional limit based on rupture length; and 

magnitude 8.25, the 1906 San Francisco earthquake. Table 

15 is a tabular representation of equation 7.

Equation 7 is simpler and quite different from its 

post-1939 counterpart found in Steinbrugge and Algermissen (1990, p. 60) because of the new Loma Prieta data. 

The previous PML for magnitude 8.25 with an uncertainty 

factor of 1 was 4.33 percent; here equation 7 increased the 

PML to 8.72 percent. Using magnitude 7.75 as the upper 

limit instead of 8.25, then the 8.72 percent PML would be 

reduced to 7.46 percent.

The precision of the equations exceed their accuracy. 

We judge the computational results to be reasonable to 

one and one-half significant figures, at best. The best reliability is between 5 and 15 percent deductibles and between magnitudes 6 and 7.5. It remains to be seen how 

future earthquakes will affect the equations.

1992 Landers Earthquake: California Residential 

Earthquake Recovery Plan Deductible

Subsequent to the Loma Prieta event, the Landers 

earthquake of June 28, 1992, provided a partial opportunity 

to examine equation 7 at low deductibles. Loss information 

came from the California Residential Earthquake Recovery 

[Insurance] Plan (CRER). This insurance program, enacted 

by the California legislature, was in existence for a short 

period of time before being repealed. Seventeen California 

earthquakes occurred during the operation of this plan, all 

in 1992. The Landers earthquake was the only one which 

contributed a useful amount of data.

Both the CRER deductible and maximum amount of 

the policy were low, thereby allowing first loss insurance 

coverage not available in the commercial market. The deductible was one-half of one percent of the amount of the 

homeowners fire insurance policy, but not less that $1,000. 

The maximum amount of CRER earthquake insurance was 

$15,000. A total of 4,341 post-1939 wood frame dwellings 

had losses over their deductible and with damage not exceeding the $15,000 policy limit. The dollar deductible 

when converted to a percentage ranged from 0.5 to 3 percent for almost all of these dwellings.

The number of insured dwellings having losses or 

losses under the deductible was not available. This meant 

that equation 7 could not be confirmed by Landers data at 

low deductibles, but the slope of both curves could be examined by normalization. Figure 11 shows the equation 7 

curve and also the Landers data, normalized at one percent. Slope differences are substantial see the upper right

Dwelling and Mobile Home Monetary Losses Due to the 1989 Loma Prieta, California, Earthquake, with an Emphasis on Loss Estimation B27
hand corner of this figure. One reason is apparently due to 

insurance adjuster practices regarding losses at or just 

over the deductible. About 66 percent of the claims were 

between 0.75 and 1.75 percent deductible. There are other 

problem areas when quantifying very small losses; see the 

last paragraph of "PMLs and Equations For Loss Over 

Deductible," above.

Referring again to the upper right hand corner of figure 11, the Landers normalized data were nearly identical 

for the range between the 0 to 6 mile PML zone to 0 to 40 

miles from the fault. This suggests that the slope of the 

curve remains reasonably constant for this range of distances at low deductibles.

Pre-1940 Construction

The previous discussion under "Losses by Age 

Group" ruled out any meaningful loss over deductible 

equations for pre-1940 construction. In the absence of adequate new data, these and the PML may be estimated by 

using the PML ratio from equations 4 and 5 of Steinbrugge and Algermissen (1990, p. A60), being 2.3. An approximate pre-1940 estimate would be to double the 

values determined by equation 7 in the present study.

However, the need for pre-1940 information elsewhere 

throughout California is limited. Contemporary Department 

of Insurance records provided statewide information on the

LLJ 5

CO

h I

o

UJ

o

UJ

> 

o

oo 

oo 

o

1.5

Normalized at 

1* deductible

Computed for 

1992 Landers 

earthquake

0.5 1.0 1.5 2.0 

DEDUCTIBLE, IN PERCENT

2.5

5 10 15 

DEDUCTIBLE, IN PERCENT

20

Figure 11 . Equation 7 loss over deductible curve compared with Landers earthquake 

data. Upper right hand corner shows slope comparisons at 1 percent normalization.

B28 Estimation of Earthquake Losses to Housing in California
building value of all fire insurance policies. The dividing age 

was post-1940 instead of post-1939. The percentage of value 

of the older (pre-1940) to total value was:

5.8 percent, source B,

7.1 percent, three largest companies, including source B.

These three companies had slightly over a 50 percent 

market share of California and represented values exceeding $250 billion. The value of the older housing stock as a 

percentage of the total value will be constantly decreasing. 

Earthquake retrofitting will effectively remove older housing from the more vulnerable category.

Dwelling Contents Losses

While the paid contents losses are accurate, contents 

values are generally considered to be of poor quality. 

Building values can be reasonably determined on a square 

foot basis. No good counterpart exists for contents values 

unless they are scheduled items with appraised values.

The model used for estimating contents loss is based 

on the premise that contents damage and their losses have 

a relationship to the amount of building damage. Both 

building and contents are subjected to short period ground 

motions. Duration of strong shaking will produce increasing amounts of damage to both contents and building.

This model is appropriate while the building maintains its integrity. Decrease in structural integrity becomes 

increasingly common after 50 percent building losses; 

these losses are usually associated with geohazards in 

post-1939 construction. Damage below 50 percent generally indicates that large sections of ceilings did not fall. 

Chimney failure may not result in major contents damage, 

and very small permanent ground displacements probably 

will have little effect on building and contents damage.

Table 16 shows contents loss as a percentage of paid 

building loss, that is, as the percent loss over the building 

deductible. The data are most reliable in the deductible 

range of 5 to 10 percent. Those below 5 percent and over 

10 percent had a rapidly decreasing number of dwellings 

in their data base. It will be recalled that source B deductibles were a variable dollar deductible which converted to 

a wide range of percent deductibles.

An example may give insight on how the information 

can be used. At 10 percent deductible for the nine-county 

study area, the contents loss as a percent of the paid building loss (loss over deductible) was 24.7 percent. Assume a 

$100,000 building with a $10,000 deductible and a loss 

over the deductible of $7,000. The contents loss would be 

0.247x$7,000, or $1,729.

The percentages in each of the four study areas, particularly in the 5 to 10 percent of each range, indicate a 

uniform percentage. The bottom of the table shows building weighted averages for the entire range from 1 to 20

Table 16. Contents loss as percent of building loss as a function of percent deductible.

[Source B deductible data, in dollars, converted to percent 

deductible. Converted deductibles grouped plus or 

minus 0.5 percent.]

Contents Loss as Percent of Paid Building Loss

Pet. 9-County 

Ded. Study Area

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

1 thru 20

5 thru 10

27.3

33.3

22.8

33.4

25.1

21.4

17.6

19.7

20.8

24.7

21.5

24.7

20.0

42.7

24.6

29.8

lOt. 9

47.2

85.7

12.1

22.5

20.8

PML Zone

83.3

51.3

27.1

44.1

33.2

26.3

21.8

22.4

21.4

25.2

25.6

30.5

19.9

65.4

24.1

284.2

16.0

6.5

0.0

12.1

26.2

23.7

PML Zone, 

Excluding 

ZIP 95030

130.2

24.2

24.6

35.0

25.0

24.4

19.9

23.5

19.1

23.3

25.7

25.0

20.3

50.6

33.0

284.2

16.0

6.5

0.0i

23.7

21.9

Within 

10 Miles 

Of Fault, 

Excluding 

PML Zone

11.5

44.6

18.0

23.5

15.6

21.2

16.5

29.6

18.2

22.2

32.8

23.1

19.4

3.4

29.8

100.9

0.0i

143.1

0.0

21.6

20.6

Number of buildings:

2,612 1,096 772 463

buildings have this deductible.

percent and also those for 5 to 10 percent, with the latter 

containing the large majority of the data.

The effect of geohazards on values in table 16 values 

becomes apparent when comparing the percent contents 

losses in the 5 to 10 percent range at the bottom of the 

table. For example, use the nine-county study area (column 2) as the basis for comparisons. The PML zone has 

23.7 percent loss while the nine-county study area has 

20.8 percent; the geohazards in the PML zone account for 

this. Excluding ZIP 95030 (column 4) and thereby eliminating much of the geohazard losses will reduce the compared values as expected.

A comparison of the nine-county study area with the 

area within 10 miles of the fault but excluding the PML 

zone (column 5) has two interesting features. First, the 

percentage in column 5 is lower than that in column 2.

Dwelling and Mobile Home Monetary Losses Due to the 1989 Loma Prieta, California, Earthquake, with an Emphasis on Loss Estimation B29
Table 17. Contents loss as a percent of building 

value for nine-county study area.

[Data source B. Limited to buildings having loss 

over deductible.]

Contents Loss 

Building As a Percent of 

Value Building Value

Under $100,000

$100,000 - 150,000

$150,000 - 200,000

$200,000 - 250,000

$250,000 - 300,000

Over $300,000

3.23

2.35

2.70

3.32

3.67

2.95

Number 

Of 

Buildings

265

996

646

341

160

206

Column 2 percentages contain all geohazards, including 

those in the San Francisco Marina as well as those in the 

PML zone; therefore column 2 values should be higher 

than column 5 values. Of importance is the little difference in percentages, indicating that the spectacular geohazard building damage had little regional impact in the 

case of the Loma Prieta earthquake. Second and commingled with the first, it also suggests that loss attenuation 

with distance is not overly important and consistent with 

our model. The model assumes that magnitude increased 

the duration of shaking and the accelerations, but did not 

change the contents to building relationship.

Contents losses will be 20 to 25 percent of structure 

loss on the average. Many times there will be no structure 

loss, but contents losses. Similarly, it is possible to have 

heavy structure loss with minor contents losses. If the deductible is zero, there will be reported contents losses, but 

equation 8 will overestimate the contents losses, because 

there is usually no deductible applied to contents losses. 

Therefore, the amount of contents losses is independent of 

structure losses by deductible, in the aggregate. The 25 

percent reported ratio was based on the reported losses for 

structure and contents.

Modifying equation 7 to include a user-selectable 

contents loss factor:

LD = [2.534468 (M - 5) + 0.5] e-°- 188469 D x F X C 

where the new term is:

C = factor for contents loss, 

which if included as 1.25, the equation then becomes:

LD = [3.168085 (M - 5) + 0.625] e-°- 188469 D x F (8) 

and previously defined terms are: 

LD = percent loss over deductible, 

D = deductible in percent,

Table 18. Ale loss as percent of building loss as a function 

of percent deductible.

[Source B deductible data, in dollars, converted to percent 

deductible. Converted deductibles grouped plus or 

minus 0.5 percent.]

Ale Loss

Pet. 9-County 

Ded. Study Area

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

1 thru 20

5 thru 10

0.9

4.4

5.1

11.0

6.1

6.8

7.4

7.9

9.1

10.9

9.1

14.2

14.5

10.1

19.0

8.2

8.3

30.9

0.0

19.1

8.4

8.1

as Percent of Paid Building Loss

PML Zone

8.0

8.2

5.6

13.8

7.5

9.4

10.0

9.9

9.9

15.8

15.1

16.5

23.3

13.3

22.3

0.0

18.8

0.0

0.0

19.1

10.8

10.1

PML Zone, 

Excluding 

ZIP 95030

11.4

5.0

3.1

12.4

3.9

6.4

4.8

9.8

6.4

12.2

10.9

14.6

14.0

10.7

11.5

0.0

18.8

0.0

0.0i

8.0

7.3

Within 

10 mil es 

Of Fault, 

Excluding 

PML Zone

0.0

0.0

0.0

3.6

4.9

8.1

4.3

9.7

7.9

3.3

0.4

10.0

0.1

8.1

14.7

58.9

0.0i

0.01

6.0

7.0

Number of buildings:

2,612 1,096 772 463

*No buildings have this deductible.

M = magnitude, and 

F = user-selected uncertainty factor.

When settling earthquake claims, source B had a practice whereby contents and Ale losses were paid in full up to 

the earthquake insured limit and applied the deductible to 

the structure loss if the contents and Ale loss did not exhaust the limit. Not all companies followed this procedure. 

Comparisons showed that this variability was minor except 

where numerous large geohazard losses occurred.

Table 17 shows the variations of contents loss as a 

percent of building value. The lowest and highest value 

groupings are contrary to the ascending order of percentages in the second column.

B30 Estimation of Earthquake Losses to Housing in California
Table 19. Building losses for selected ZIPs at distant locations.

[Data for source B. ZIP centroids are located 30 or more miles from the fault. Limited 

to ZIPs haying 10 or more earthquake insured buildings. Also limited to ZIPs having 

average paid building losses of 1.0 percent or more.]

ZIP

93926

94401

94621

94124

94607

94122

94115

94608

94118

94123

94121

Fault 

Distance 

(miles)

32.4

32.4

42.3

44.0

46.8

48.0

48.4

48.6

48.7

49.2

49.3

Number 

Insured

All Ages

10

210

82

62

22

351

68

45

142

66

184

of Eq. 

Bui I dings

Post -1939

10

193

63

52

15

246

18

36

44

17

89

Average 

Loss Over 

All Ages

2.1

2.3

2.7

1.2

3.8

1.7

1.0

1.0

1.2

3.6

2.3

Percent 

Deductible 

Post -1939

2.1

2.5

2.1

1.5

0.0

0.8

1.8

1.2

1.4

1.1

1.2

Post Office

Gonzales

San Mateo

Oakland

San Francisco

Oakland

San Francisco

San Francisco

Oakland

San Francisco

San Francisco1

San Francisco

Marina district in San Francisco

Additional Living Expense (Ale) for Dwellings

Table 18 provides information on living expenses 

when a dwelling was damaged to such an extent that it was 

not habitable. Additional living expenses (Ale) were examined in the same manner as that for contents losses discussed in the previous section compare tables 16 and 18. 

Ale losses could be due to building damage or due to 

causes not related to the structure, such as the loss of utilities and road closures in landslide areas. Inclement weather, 

such as below freezing, could radically change the Ale loss 

pattern. The Loma Prieta findings are presented here for 

information purposes. It may have limited application to 

homeless estimation algorithms.

Geographic Distribution of Losses

Figure 12 shows the geographic distribution of paid 

building loss plus deductible as a percentage of value by 

ZIP. Data were from source B, table 44, column 28. Plotted locations were limited to ZIPs with 10 or more earthquake insured buildings. Age was not considered. An open 

circle means that the average percent losses is less than 

0.1 percent while a solid circle means over 0.1 percent. 

Solid circles with adjacent percentages are for losses over 

1.0 percent.

Loss data become meager beyond 15 miles from the 

faulting. Examine column 16 of table 44 beginning at 15 

miles (column 2). Twenty-seven is the largest number of 

buildings in any ZIP having paid losses. Indeed, the large 

majority of entries in this column is below 10 structures. 

Any conclusions to be made from the discussion which

follows must keep this data distribution in mind. However, 

certain patterns emerge. Open circles prevail at distances 

from about 15 miles around the fault to about 40 miles to 

the northwest. Beyond 40 miles to the northwest, solid circles prevail principally in San Francisco, Oakland, and 

Berkeley. This pattern is clearly evident in figure 13 which 

plots distance from the fault against average percent losses. 

ZIPs with losses below 0.5 percent were not plotted, 

thereby not plotting the large majority of ZIPs beyond 15 

miles. The losses within the 6 mile PML zone are very high 

since geohazards were not eliminated.

Figure 13 is another perspective on figure 12 information. The losses beyond 30 miles in figure 13 warranted 

examination since they resemble those from 10 to 15 miles. 

Table 19 compares the influence of building age on average 

percent losses of 1.0 percent or over. Four of the eleven 

ZIPs in table 19 show increases in losses when older homes 

were deleted from the data set. Much of ZIP 94401 (San 

Mateo) is mapped as having low to high relative liquefaction susceptibility (Youd and Perkins, 1987). Paid losses in 

this ZIP were confined to 14 post-1939 buildings. Six of 

these in the liquefaction susceptibility area had losses ranging from over 20 percent to almost 90 percent. The USGS 

topographic map for San Mateo, dated 1915, shows the 

area to be underlain with sloughs and marshes. Geohazards 

seem to be one reason for this anomaly.

The three age anomalous San Francisco ZIPs in 

table 19 were dominated by four large losses, three of 

which were built between 1942 and 1954 and one in 

1925. The small data set was a contributing factor to the 

problem.

A most likely factor which increased all losses in San 

Francisco was the construction. See previous discussion

Dwelling and Mobile Home Monetary Losses Due to the 1989 Loma Prieta, California, Earthquake, with an Emphasis on Loss Estimation B31
MONTEREY 

BAY

B32 Estimation of Earthquake Losses to Housing in California
"^ Figure 12. Geographic distribution of average building 

loss as a percent of insured value using data source A information. Each open or solid circle represents the centroid of a 

postal ZIP having more than 10 wood frame earthquake insured buildings. Solid circles have, on an ZIP average basis, 

losses equalling or exceeding 0.5 percent. Open circles have 

lessor average losses or none. Solid circles with average losses 

equalling or exceeding 1.0 percent also show the percent loss. 

Data shown are from table 44 (at end of report) which differ 

slightly from those used in figure 5.

on San Francisco construction under "Earthquake Intensities and Monetary Losses."

No effective loss attenuation with distance algorithms 

were constructed from these data.

Construction and Value as Variables

Source B contains considerable information on building 

values as they varied with building construction components

16

14

12

17.9JU 

95073

*

95006

 

95076

95003

95066 *.

95007*

95019

 

 95030

m 95065

 95018

95005

95062

95060

^95010

95032* 

95020

95004 0 * 

95070*

94024

95045.

 

%

v /*

94020

94022

95023

t

34401* 33926-* 

Oakland* sa 

94621

8 v>

1 1 .

ID h~ ID 

 ** <£> U. CO ID ** e\j

OCTl CrH

 oooi

i Francisco 

94121 

94122*

~f

O LlJ _j _j

Q _l 

LU <

00 <

10

< 6

=3 «/> 

£0 <

Q 

<

10 15 20 25 30 35 

DISTANCE FROM FAULT, IN MILES

40 45 50

Figure 13. Another perspective on figure 12 data and those in table 44. The plot is paid building loss plus deductible as a 

percent of value against distance from the fault. Loss percentages less than 0.5 percent are not plotted.

Dwelling and Mobile Home Monetary Losses Due to the 1989 Loma Prieta, California, Earthquake, with an Emphasis on Loss Estimation B33
Table 20. Number of stories as a 

function of building losses.

Table 21. Type of roof as a function of building losses.

[Data from source B. ZIPs within 

10 miles of the fault. Wood frame, 

post-1939 construction. Losses are 

before the deductible.]

[Data from source B. ZIPs within 

10 miles of the fault. Wood frame, 

post-1939 construction. Losses are 

before the deductible.]

Number Number of 

Stories Buildings

1

2

3

Bi level

1 & half

2 & half

3 level

Unknown

428

258

3

9

121

1

25

538

Bldg. Loss 

As Pet. 

Of Value

18.5

17.3

11.1

15.0

19.0

8.0

16.2

20.0

such as type of roof and number of stories. Numerous combinations were examined, with the more interesting of these 

summarized below.

Tables 20, 21, 22, and 23 are limited to post-1939 

dwellings within 10 miles of the surface projection of the 

fault. An important factor in all tables, except table 23, is 

that the column "Building Loss as a Percent of Value" is 

based only on dwellings having paid losses, excluding 

dwellings which did not have losses over the deductible. 

Therefore, the percentages are not PML values and are 

only useful as relative values.

Table 20 shows the percent building loss as a function 

of the number of stories. The table clearly demonstrates 

that two story structures performed as well as one story 

structures. This observation does not apply to dwellings in 

San Francisco; see discussion under "Monetary Loss," 

above.

Tile roofs are often considered to be both a life hazard and to be vulnerable to damage. Table 21 may be surprising with respect to dollar loss. Type of tile anchorage 

to its supporting members, if any, is unknown. Dollar loss 

is not necessarily indicative of life hazard, such as tile 

over exit doorways.

Masonry chimneys are especially vulnerable to damage when they are unreinforced. Fewer fail when they are 

reinforced, and essentially none fail when the shaking is 

not severe. Table 22 shows data for losses over the deductible in the heavily shaken area. There was no breakdown 

on reinforced and nonreinforced chimneys. The loss percentages in the last column indicate that building losses 

over the deductible, if anything, tend to decrease with an 

increase in the number of chimneys.

Table 23 relates dwelling value to the percentage of 

owners who chose earthquake insurance in addition to 

their fire coverage. The percentages increase from the

Roof

Type

Tile1

Other

Unknown

Number of

Bui I dings

61

538

784

Bldg. Loss

As Pet.

Of Value

17.3

20.0

18.0

or concrete

Table 22. Masonry chimneys as a 

function of building losses.

[Data from source B. ZIPs within 10 

miles of the fault. Wood frame, 

post-1939 construction. Losses are 

before the deductible.]

Number 

Masonry 

Chimneys

None

1

2

3

4

Number of 

Bui I dings

178

513

129

21

4

Bldg. Loss 

As Pet. 

Of Value

20.1

17.9

15.4

15.7

30.2

Table 23. Value as a function of 

earthquake insurance coverage.

[Data from source B. ZIPs within 10 

miles of the fault. Wood frame, post1939 construction. Losses are before 

the deductible.]

Building 

Value 

x$1000

Less $100

$101-150

$151-200

$201-250

$251-300

$301-350

$351-400

$401-450

$451-500

$501-550

$551-600

$601-650

$651-700

$701-750

Over $750

Number of 

Bui I dings

6,804

13,237

7,107

2,812

1,193

522

227

106

63

47

45

24

10

12

36

Pet. With 

Eq. Insurance

19.5

36.4

48.5

54.6

58.8

61.5

56.8

53.8

57.1

59.6

68.9

75.0

70.0

75.0

55.6

B34 Estimation of Earthquake Losses to Housing in California
under $100,000 dwellings to about $300,000, then tend to 

erratically increase. This indicates that the homeowner's 

economic status is an important factor in the purchase of 

earthquake insurance.

Modified Mercalli Intensity

Shown in figure 14 are the boundaries of the 6-mile 

PML zone and a portion of the Modified Mercalli intensity 

map including the epicentral area. The isoseismal line is 

from a portion of figure 2 in Stover and others (1990). The 

correlation between the theoretic PML zone and the isoseismal map is reasonable in the populated areas. The absence of dwellings and other structures in much of the 

Santa Cruz Mountains leaves the northeastern boundaries 

mostly undocumented (see fig. 3).

One comparison between intensity VHI and quantified 

dwelling losses for post-1939 construction is:

Percent 

PML

1989 Loma Prieta (equations 1, 2, and 3) 

PML zone, including geohazards 

PML zone, excluding geohazards 

Watsonville study area 

1983 Coalinga

17.5 

12.4 

6.5 

4.6

Correlations between mapped intensity and actual losses 

are not simple.

Other comparisons from other earthquakes show wide 

variations among intensities and losses (table 28 in Steinbrugge and Algermissen, 1990) and should be examined in 

the context of the above tabulation.

The definitions and interpretations of Modified Mercalli intensities commingled incompatible factors such as 

(1) human response, (2) functional impairments, (3) degree of building damage, and (4) geologic effects. The 

definitions use nonqualified as well as subjective terminology: "few," "many," "slight," "considerable," "good," 

and "frightened all." These terms are summarized by an 

intensity. A single intensity may be assigned to a specific 

site or more often to a large area (Steinbrugge, 1986).

There is a role for specialized equivalents to intensity 

maps intended for specific purposes such as monetary loss 

and life safety estimates. Such maps require data bases of 

structures by construction class, occupancy types, and occupant loads. These data bases must include values and 

losses sustained as well as a measure of local dynamic soil 

conditions. These data are often found in geographically 

scattered computerized systems compiled by governmental, academic, and private entities.

While one of the authors (Steinbrugge) has used 

Modified Mercalli intensities in previous studies, alternatives have also been examined. One alternative is contained in this paper. On the other hand and much in the 

maps' favor, they provide an excellent overview of overall 

effects and are vital to the historic record.

MOBILE HOMES (MANUFACTURED HOUSING)

Introduction

Information on mobile home damage and losses from 

the Loma Prieta earthquake came from three sources: source 

B (previously discussed), source C (new), and the California 

Department of Housing and Community Development 

(new). Additionally, a retrospective study of previous California mobile home experience is included for the following 

earthquakes: 1971 San Fernando, 1978 Santa Barbara, 1979 

El Centre (Imperial Valley), 1980 Livermore (Greenville), 

and 1983 Coalinga. Other earthquakes provided little useful 

information for monetary loss estimation. Although data for 

the 1984 Morgan Hill earthquake are only minimally useful, 

17 mobile homes representing 2 percent of the mobile home 

units in the Morgan Hill and Gilroy areas fell. No damage 

was found to coaches having a proprietary earthquake bracing system although nearby unbraced ones fell (Kensler, 

1985). Monetary losses were not estimated.

The number of spaces available for mobile homes is 

listed in some data bases. Since mobile home parks are 

normally at capacity, or very close thereto, the number of 

coaches in a park is considered to be the same as the number of spaces. Mobile homes, coaches, and manufactured 

housing have the same meanings in this study. They may 

or may not include contents and appurtenances, depending 

upon context.

Definition Of Mobile Home 

(Manufactured Housing)

A mobile home (manufactured housing) is defined 

here to mean a coach unit which is transported (towed) on 

wheels to a site where it can be jacked or raised off its 

wheels and leveled. The wheels, but not the axle spindles 

and drum unit to which the wheels and tires fasten, may 

be removed and stored.

The typical set-up technique for a mobile home is to 

roll the coach into place and use one of several types of 

piers placed at intervals of about 6 feet along the main 

frame. A screwjack on the top of each metal pier is then 

brought up into contact with the undercarriage and positioned until the coach is level and steady on the mounts.

Dwelling and Mobile Home Monetary Losses Due to the 1989 Loma Prieta, California, Earthquake, with an Emphasis on Loss Estimation B35
Boundary of ZIPs with 

centroids in the PML zone

Figure 14. PML zone and its relationships to the Modified Mercalli intensity zone VIII. Also shown is t

the ZIPs with centroids within the PML zone.
Other types of piers may exist such as hollow concrete 

block and sometimes treated wood blocks. Piers rest on 

concrete slabs or in some cases directly on soil. When soft 

soils are encountered, concrete block masonry or flat (cement) patio type blocks are used to spread the load and 

prevent settling. Utilities are then hooked up, an aluminum 

skirt is applied around the base, and stairs are placed at 

the doorway. Commonly, an aluminum patio cover is 

found on the door side of the coach. If the yoke-tongue at 

the forward end of the coach is left on (sometimes cut-off 

for aesthetic reasons), it is vertically supported and 

skirted.

Characteristic Damage

Structural damage to mobile homes is the result of a 

lack of earthquake bracing beneath them. Supports comprise steel piers, concrete piers, or unreinforced hollow 

concrete block (or cinder block) in almost all instances. 

These piers are intended to support vertical loads, but they 

have very little resistance to lateral loads such as imposed 

by earthquakes. These unstable conditions cause mobile 

homes to fall when the supports topple. Other instability 

problems arise on a sloping site when, to provide a 12- 

inch minimum clearance under the frame at one end of the 

unit, the other end may be 36 to 40 inches above the surrounding grade.

Excluding coach contents, coaches are essentially undamaged when they do not fall from their supports. Generally, recaulking of roofs where double-wide units join or 

where the patio/porch roof joins the coach is the extent of 

needed repairs. When they do fall, the skirt is normally 

severely damaged, the frame may be bent, and holes may 

be punched through the floor by the fallen coach supports. 

Also, damage often will be severe to the adjacent porches 

and attached patio awnings which are separately supported 

on the ground.

It is important to note that once a coach falls off its 

supports, damage and losses will not significantly increase 

beyond the initial damage. This remains true even for 

great earthquakes of long duration. Total losses are normally not expected without ensuing fire or a geohazard 

problem such as landsliding.

Loma Prieta Earthquake

Source B Data

Source B insured 8,620 mobile homes in the 14 

county study area. It contained information on each insured mobile home in similar detail to that provided for 

dwellings. Table 24 shows a breakdown of these mobile 

homes in parks as well as those not located within parks,

Table 24. Mobile home (manufactured housing) losses 

in 14 counties.

[Data from source B.]

Number of Mobile Homes

County

A I ameda

Contra Costa

Mar in

Monterey

Napa

Sacramento

San Bern" to

San Francisco

San Joaquin

San Mateo

Santa Clara

Santa Cruz

Solano

Sonoma

In a Park

557

682

87

450

507

1,101

60

2

511

207

1,414

607

574

822

Isolated1

55

70

8

183

40

197

27

0

174

8

26

44

35

172

Number of 

Paid Losses2

2

1

0

18

0

1

24

0

1

1

43

177

0

0

Totals 7,581 1,039 268

lM Isolated" normally means not in a mobile home park. 

2After a 10 percent deductible based on coach value.

with the latter listed as "isolated." Earthquake insurance 

policies covered the coaches, their contents, and additional 

living expenses. The deductible was 10 percent of the 

coach value and was applicable to coach and contents 

losses. Additional living expenses were not subject to the 

deductible, but they reduced the amount available for paid 

coach and contents losses. The last column in table 24 

shows that 268 mobile homes located in parks had losses 

over the 10 percent deductible. Essentially all mobile 

homes with paid losses were in the four counties of Monterey, San Benito, Santa Clara, and Santa Cruz. Santa Cruz 

dominated. Isolated mobile homes are not significant in 

this study since they were so few in number.

Table 25 lists mobile home losses in the PML zone 

and also those up to 10 miles from the fault. Column 3 

lists the number of mobile homes carrying earthquake insurance and column 4 lists those with paid losses. Columns 7, 8, and 9 show the paid losses. The last column 

shows the average loss over the deductible for each ZIP. 

The 3.8 percent loss over the deductible for the PML zone 

suggests that, despite coaches falling off their supports, 

most losses were far from being total. This subject will be 

further examined.

Figure 15 is based on table 25 and shows the relationship between loss over deductible and distance from a ZIP 

centroid to the fault. ZIPs with fewer than 37 insured mobile homes were not plotted. Except ZIP 95020 (Gilroy),

Dwelling and Mobile Home Monetary Losses Due to the 1989 Loma Prieta, California, Earthquake, with an Emphasis on Loss Estimation B37
Table 25. Mobile home losses 10 miles or less from the fault.

[Data from source B. excluding ZIP 95030. Deductible is 10 percent of coach value and applies 

to coach plus contents losses. ZIP to fault distances are to the ZIP centroid and not to 

centroid of parks. Only ZIPs with earthquake insurance are included.]

Number of 

Mobile Koines

ZIP to Fault With

Distance Eq.

ZIP (miles) Insur.

With

Paid

Loss

Value x$1000

Coach Conts.

Paid Loss x$1000

Coach Conts. Ale

Percent

Coach

Loss Over

Deductible

PML zone

95076

95003

95066

95073

95006

95005

95065

95018

Totals

95062

95060

95020

93907

95124

Totals

2.1

3.5

3.9

4.3

4.7

4.8

5.3

5.5

PML zone

7.5

8.9

9.6

10.0

10.0

, all of

159

63

79

82

3

4

0

6

396

Beyond PML

168

38

37

140

1

above 780

69

14

17

26

0

2

0

2

130

zone but

32

4

11

6

0

183

7,024

3,136

5,121

3,421

61

90

0

143

18,996

within

5,553

1,962

1,422

4,482

37

32,452

5,735

2,559

4,486

3,019

48

68

0

106

16,021

10 miles

4,536

1,601

1,127

3,722

28

27,035

328

69

183

135

0

6

0

2

723

of the

51

7

48

34

0

864

166

85

62

47

0

3

0

1

365

fault

30

2

9

4

0

410

59

8

12

17

0

1

0

0

96

4

0

1

2

0

103

4.7

2.2

3.6

4.0

0.0

6.7

0.0

1.2

3.8

0.9

0.4

3.4

0.8

0.0

2.7

LU

_1 

00 

I I

I 

o

ZD 

O 

LU 

O

I 

z.

LUI 

O Z. 

C£LU 

LUCJ O-CE:

LU 

CSQ.

oi

LU

> 

o

00

00

o

1 

o 

< 

o 

o

I rv>

90576

Watson ville

95003

Aptos

95073

Soquel

95066

Santa Cruz

95062

Santa Cruz

9

95020 

Gilroy

93707 <

Salinas

5060 

Santa Cruz

2468 

DISTANCE FROM FAULT, IN MILES

10

Figure 15. Loma Prieta earthquake. Mobile home loss over 

10 percent deductible as a function of distance from the fault 

for parks are grouped by ZIP; in figure 16, parks are individually plotted. Excluded are ZIPs with no losses or fewer than 

10 mobile homes. Names are post office names and may 

include large rural areas. Data from source B.

the data are well-behaved and suggest a curve for the 

upper limit of distance versus coach losses. This relationship would be limited to the 10 percent deductible.

An alternate viewpoint of loss versus distance is figure 16 where the distances from individual mobile home 

parks to the fault are shown. Distances are those from the 

parks and not from ZIP centroids. The triangles are for the 

Watsonville ZIP; these parks are also those closest to the 

fault. Solid circles are those parks along Monterey Bay 

plus those westerly of the fault. Open circles are for parks 

east of the fault from the Santa Clara Valley southward to 

Hollister. Data scatter among parks can be attributed to 

local soil conditions and also to type of piers supporting 

the coach (see a following discussion under "California 

Department of Housing and Community Development"). 

Directionality of seismic waves and soil amplification of 

ground motions may have contributed in some instances. 

Parks with fewer than 10 insured mobile homes were excluded. Some contiguous parks were combined. The large 

loss of 5.2 percent at distance 14 miles (San Jose) is due 

to heavy damage to one coach out of 12.

Information additional to figure 16 losses in Watsonville, Corralitos, Gilroy, and Hollister is shown in table 26. 

The Watsonville and near vicinity mobile home information

B38 Estimation of Earthquake Losses to Housing in California
is presented as a comparison to dwellings in the Watsonville 

study area (fig. 7). The number adjacent to each mobile 

home park in figure 7 can be associated with the park name 

and its data in table 26. Two parks, Rancho Corralitos in 

Corralitos and Portola Heights in Watsonville, are located 

on steep slopes. Interestingly, neither of these had losses 

over the deductible exceeding 8.1 percent, the average for 

Watsonville and near vicinity. Rancho Cerritos in Watsonville was near the steep slopes of Struve Slough and this 

probably influenced its high loss shown in table 26.

One mobile home park, the Riverside in Watsonville 

(fig. 7), was located adjacent to the dike for the Pajaro 

River and also within the river's flood plain. This park 

was also adjacent to the heavily damaged central commercial district. Only one coach fell in this small park of 28 

coach spaces. All other parks within the Watsonville city 

limits were on higher and apparently firmer ground. These 

other parks had higher percentages of fallen coaches; the 

reason for this anomaly is not clear.

Loss variations within Watsonville may not be overly 

meaningful when considering the amount of available

data. On the other hand, the comparative damage between 

the two parks in and near Hollister is significant and can 

be attributed to soils. Mission Oaks mobile home park in 

Hollister is located on quite soft alluvial soil on the bank 

of the San Benito River. The very low losses at Fairview 

Mobile Manor are in contrast. This latter park is located 

3.2 miles to the east of Mission Oaks, on higher ground, 

and about 3 miles from the San Benito River. Soils seem 

to be firmer. In any event, the difference in losses does not 

appear to be associated with construction and is most 

likely due to geohazards.

The foregoing data do not differentiate between earthquake braced and nonbraced mobile homes. Table 27 displays the number and type of bracing within various 

geographic areas. Earthquake bracing, when it occurs, exists between the coach floor and the ground surface. Four 

different kinds of bracing were identified, often by insurance agents. Undoubtedly "wind" bracing was confused 

with earthquake bracing in many cases, probably because 

the persons making the decisions were normally not technically oriented. However, it is evident that coaches without

18

16

14

12

10

95033 

Hol1ister 

O

95020 

Gilroy

(1,95111 

San Jose

6 8 10 12 14 

DISTANCE FROM FAULT. IN MILES

16 18 20

Figure 16. Loma Prieta earthquake. Percent loss over 10 percent deductible as a function of 

distance from the fault for individual mobile home parks; in figure 15, parks are grouped by 

ZIP. Solid triangles are parks located in Watsonville ZIP 95076. Solid circles are parks in a 

coastal community, or nearby. Open circles are parks to the east of the fault, ranging from the 

Santa Clara Valley to Hollister. Data from source B.

Dwelling and Mobile Home Monetary Losses Due to the 1989 Loma Prieta, California, Earthquake, with an Emphasis on Loss Estimation B39
Table 26. Coach loss data on selected mobile home parks.

[Data from source B. Losses are after the 10 percent deductible.]

Fault Spaces Insured Coaches Paid Pet. Loss

Dist. in Number Value Loss Over

Location and Park Name (miles) Park1 Coaches (x$1000) (x$1000) Deduct.

Watsonville and near vicinity:

1 Meadows Mobile Manor 2.1 276 13 623 11

2 Portola Heights 2.8 119 12 691 40.

3 Green Valley Village 2.8 105 18 800 78.

4 Colonial Manor 2.9 71 4 133 5.

5 Rancho Cerritos 3.3 144 9 476 124.

6 Monterey Vista 3.3 122 15 713 18.

7 Riverside 3.5 28 n.a. n.a. n.a.

8 Freedom 2.0 14 n.a. n.a. n.a.

9 Pinto Lake 0.3 174 n.a. n.a. n.a.

Watsonville subtotal 1,053 71 3,436 278.6

1.8 

5.9 

9.9 

4.2 

26.1 

2.5 

n.a. 

n.a. 

n.a.

8.1

Corralitos:

Rancho Corralitos 0.0

Gilroy:

Pacific Mobile Estates 8.8 178

Hoi lister and near vicinity:

Mission Oaks 16.7 225 

Fair-view Mobile Manor 18.7

10

18

39

15

573 37.3

688 41.7

6.5

6.1

1,279 215.2 16.6

448 0.7 0.1

n.a. means not available.

California Department of Housing and Community Development (1989?), p. 2. 

2Numbers against park names identify locations on figure 13.

Table 27. Type of foundation anchorage for mobile homes.

[Data from source B. Includes all coaches, with or without earthquake 

insurance.]

14 Counties

Type of

Foundation

Dug in

EQ braced

Permanent fdn.

"Wind" braced

No bracing

(Note

Numbr.

15

70

406

740

7,389

1)

4 Counties

(Note 2)

Pet.

0.

0.

4.

8.

85.

2

8

7

6

7

Numbr.

4

31

107

303

2,366

Pet.

0.

1.

3.

10.

84.

1

1

8

8

2

PML Zone

(Note 3)

Numbr.

0

7

24

15

352

Pet.

0.0

1.8

6.0

3.8

88.4

ZIP 95076

(Note

Numbr.

0

2

6

6

145

4 )

Pet.

0

1

3

3

91

.0

.3

.8

.8

.2

Totals 8,620 2,811 398 159

Note 1: Alameda, Contra Costa, Marin, Monterey, Napa, Sacramento, San 

Bern"to, San Francisco, San Joaquin, San Mateo, Santa Clara, Santa 

Cruz, Solano, and Sonoma counties. Total of 14.

Note 2: Monterey, San Benito, Santa Clara, and Santa Cruz counties. 

These were the counties with the largest number of losses.

Note 3: ZIPs 95003, 95005, 95006, 95018, 95065, 95066, 95073, and 95076. 

All are in the PML zone. ZIP 95030 was excluded.

Note 4: ZIP 95076, Watsonville. 

B40 Estimation of Earthquake Losses to Housing in California
Table 28. Relationships among losses and values for mobile home coaches, contents, 

and Ale.

[Data from source B. Losses are before the deductible. All mobile homes having paid 

coach losses.]

Percentages

Coach Value

Under $40,000- $70,000 

$40.000 $70.000 And UD

Geographic 

Distribution

Paid PML ZIP 

Claims1 Zone 950762

Contents loss as 

percent of coach loss: 19.6 49.0 33.4

Contents loss as

percent of contents value: 3.8 4.8 3.1 

Contents loss as

percent of coach value: 3.1 4.2 2.9 

Coach loss as

percent of coach value: 15.9 8.6 8.7 

Ale loss as

percent of coach value: 1.2 1.0 0.5

Contents value as

percent of coach value: 88.2 86.5 92.6

Ale loss as

percent of coach loss: 7.3 12.2 6.2

Number of coaches: 123 115 30

33.9 43.9 45.9

4.2 5.8 5.6

3.6 5.0 4.6

10.7 11.4 10.1

1.0 1.5 1.8

88.6 86.6 83.2

9.1 12.9 17.3

268 131 69

JAll coaches having paid losses in the Loma Prieta earthquake.

Watsonville ZIP.

any kind of recognized bracing hovered between 85 and 90 

percent.

Source B had 28 paid losses for coaches having some 

form of earthquake or lateral force bracing. A stricter interpretation of earthquake bracing probably would have greatly 

reduced this number (see following section "California Department of Housing and Community Development").

Eleven coaches in parks had losses over 60 percent of 

coach value when the deductible was added to the paid 

loss. Of these 11 coaches, 6 were located in the Mission 

Oak Park in Hollister (see table 26). As previously mentioned, high losses in this park were most likely due to a 

soil related geohazard. Of the remaining 5 coaches, their 

percent losses in descending order were: 91.7, 90.8, 79.0, 

64.5, and 63.4 percent. None had recognized earthquake 

bracing systems of any sort. Locations were widely scattered: Hollister, Scotts Valley, and the contiguous coastal 

communities of Capitola-Aptos-Soquel. In summary when 

excluding fire and geohazards, no coaches in parks were 

total losses: 2 had losses over 80 percent, and 5 had losses 

over 60 percent. These 11 high loss coaches are a very 

small number of the 7,581 coaches in the 14 county study 

area (table 24).

In the PML zone, the 5 highest contents losses in percentages of their insured values were 36.6, 36.2, 29.8, 28.2, 

and 25.5 percent. Contents losses exceeding 50 percent of 

insured contents value are not expected when geohazards

and fire following the event are excluded. Single-wide 

coach losses were compared with double-wide and larger 

coaches. Excluded were braced coaches. Single-wide 

coaches performed marginally better than the others out of 

a population of 231 coaches (5.9 versus 6.2 percent, respectively). Coach age and its loss were examined. The percent 

coach loss over deductible for coaches with paid losses by 

decade are as follows:

Decade

1960-69

1970-79

Post-79

Number Percent Loss 

Coaches over Deductible

49

179

39

11.7

11.2

8.2

This suggests that buyers of new or moved mobile homes 

may have chosen to include earthquake bracing.

Table 28 shows the relationships among losses and 

values among mobile homes. This will be discussed along 

with source C information in the next section, "Source C 

Data."

Source C Data

Source C, which is also a significant writer of earthquake insurance for mobile homes, provided both pre- and 

post-deductible loss information on each coach, its contents,

Dwelling and Mobile Home Monetary Losses Due to the 1989 Loma Prieta, California, Earthquake, with an Emphasis on Loss Estimation B41
Table 29. Mobile homes with paid losses in the 

PML zone.

[Data from sources B and C. ZIP 95030 excluded.]

Mobile Homes 

With Paid Losses

ZIP

95076

95003

95066

95073

95006

95005

95065

95018

Post office

Watsonvi I le

Aptos

Santa Cruz

Sequel

Boulder Creek

Ben Lomond

Santa Cruz

Felton

Source B

69

14

17

26

0

2

0

2

Source C

54

17

31

5

0

0

0

0

Totals 130 107

and Ale (loss due to additional living expenses). Source C 

information was by ZIP code and not by address. It lacked 

information on insured mobile homes not having paid 

losses. This lack precluded an analysis of loss over deductible and of PML values.

Source C had 228 paid mobile home claims, 3 with 

ensuing fire loss. Of these, 179 had a 5 percent deductible; 

29 had a 2 percent deductible; and 17 had other deductibles. Of the fire losses, one was a total loss, the second had 

a 70 percent loss before the deductible, and the third was 

under 50 percent. There were 107 paid claims within the 

PML zone, excluding ZIP 95030. By comparison, source B 

had 268 paid claims over the 10 percent deductible. A more 

detailed comparison on a ZIP basis for the PML zone is 

shown in table 29.

Ratios in the form of percentages among coaches, 

contents, and Ale are given in tables 28 and 30. These

Table 30. Relationships among losses and values for mobile home coaches, contents, and Ale.

[Data from source C and combined sources B and C. Losses are before the deductible. All mobile homes 

having paid coach losses.]

Coach Value

Percentages Under 

$40.000

$40,000- 

$70.000

$70,000 

And UD

Geographic 

Distribution

Paid 

Claims1

PML 

Zone

ZIP 

950762

SOURCE C

Contents loss as percent of coach loss: 30.1 30.8 52.6

WEIGHTED AVERAGES OF SOURCES B AND C

34.7 34.6 27.4

Contents loss as percent of contents value:

Contents loss as percent of coach value:

Coach loss as percent of coach value:

Ale loss as percent of coach value:

Contents value as percent of coach value:

Ale loss as percent of coach loss:

Number of coaches:

8.6

4.9

16.3

1.2

56.8

7.3

37

8.5

4.6

15.0

0.9

54.3

6.1

151

12.6

6.8

12.9

0.5

53.8

3.7

30

9.4

5.1

14.7

0.9

54.4

5.8

218

12.5

6.8

19.7

1.3

54.6

6.5

104

15.3

8.1

29.4

2.3

52.7

7.7

53

Contents loss as percent of coach loss: 22.5 36.1 45.1

Contents loss as percent of contents value: 4.8 6.6 6.7

Contents loss as percent of coach value: 3.6 4.4 4.9

Coach loss as percent of coach value: 16.0 12.3 10.9

Ale loss as percent of coach value: 1.2 1.0 0.5

Contents value as percent of coach value: 75.4 67.7 72.7

Ale loss as percent of coach loss: 7.3 7.9 4.7

Number of coaches: 160 266 60

34.4 38.2 32.7

6.2

4.4

8.3

5.9

12.7 15.4

0.9 1.4

9.0

6.2

19.1

2.0

70.2 70.7 69.0

7.2 8.9 10.4

486 235 122

*AU coaches having paid losses in the Loma Prieta earthquake. 

Stetsonville ZIP.

B42 Estimation of Earthquake Losses to Housing in California
percentages fall into two categories: (1) coach value, and 

(2) geographic distribution. The percentages give insights 

into data comparisons and thereby indicate the variations 

which may be expected among various data sources. Secondly, they provide a basis for loss estimation applications. For example, visual inspections may allow quick 

estimates on the amount of coach damage and thereby 

coach loss; the contents loss to coach loss percentage allows a quick estimate on the amount of contents loss when 

visual inspections must be limited to the exteriors. This 

will be further discussed under "Test of Rapid Loss Estimation, El Centro." Thirdly and for loss estimation for 

postulated earthquakes, the percentages allow for estimates 

on other losses when the PML has been determined. Tables 28 and 30 are pilot in nature and should be used with 

considerable care and judgment.

A detailed example of one application is examined. 

Columns 5 and 6 of tables 28 and 30 may be the more 

significant of those in these tables. Compare contents loss 

as a percent of coach loss for both sources B and C first 

line in each table. Source C values (table 30) are essentially identical: 34.7 percent and 34.6 percent; those for 

source B are 33.9 percent and 43.9 percent. This is better 

agreement than might be expected. The weighted averages 

of these are found on the bottom half of table 30: 34.4 

percent and 38.2 percent, respectively. For applications, 

one may reasonably judge an average of 1/3, that is, on an 

aggregate basis the contents loss will be 1/3 of that for the 

coach. A similar approach was used for wood frame 

dwellings where, in table 16, the average was about 1/4 

instead of 1/3. The commentary on the dwelling percentage also largely applies here and should be referred to for 

additional information. In the case of mobile homes where 

coaches can readily fall from their vertical supports, contents losses may be large for items such as overturned refrigerators which may not overturn in dwellings remaining 

on their foundations. This is one seeming explanation for 

the mobile home percentages averaging around 30 to 35 

percent while those for wood frame dwellings were about 

20 to 25 percent (table 16). Only experience from future 

earthquakes will provide definitive percentages for tables 

28 and 30.

Not all comparisons are as good. Potential sources of 

errors inherent in all comparisons are company market 

shares which differ among parks and their geohazards.

California Department of Housing and Community 

Development

The California Department of Housing and Community Development (acronym HCD) has the primary responsibility for mobile homes (manufactured housing) in 

California. Local jurisdictions may assume this responsibility if they so choose. Since 1985, this state agency has 

certified earthquake bracing systems and has made this

certification generally known to mobile home owners. 

However, for years prior to 1985, there were sales of noncertified systems. Also, owners sometimes had installed 

their own bracing, or left inflated tires on the coaches to 

minimize the amount of coach drop during an earthquake. 

After the Loma Prieta earthquake, the department 

made a field examination of damage found in mobile 

home parks (California Department of Housing and Community Development, 1989?). Pertinent information has 

been abstracted:

Within San Benito, Santa Clara, and Santa Cruz counties there are 

193 mobile home parks containing 24,438 manufactured homes. 

Seventy-five (75) of the parks (39%) and 9,243 of the spaces 

(38%) are subject to HCD enforcement jurisdiction with the balance subject to local government jurisdiction. There were reportable damages to manufactured homes in approximately twentyseven (14%) of the parks within these counties. The Division's 

initial assessment of the performance of manufactured home support systems was conducted within these twenty-seven (27) parks. 

....(p. 2)

Of the 592 homes that went down in the 27 parks surveyed, 301 

were homes installed on steel piers (51%), 223 were installed on 

concrete piers (38%) and 68 were installed on concrete blocks 

(11%). All of these support systems for manufactured homes are 

approved under HCD regulations, ...... (p. 4)

Their findings from this initial assessment are found in 

columns 3, 4, and 5 of table 31.

Following the initial assessment, as time permitted, Division staff 

conducted a more detailed evaluation of the 12 parks where damage was the heaviest. Within these 12 parks were 479, or 81%, of 

the 592 homes down. .....(p. 8)

Their findings of this second assessment are found in columns 5 through 11 in table 31. Their report concludes:

A clear result of the evaluation of performance from different 

types of manufactured home support systems is that there are substantial differences. It is also clear that the prior observance of 

Division inspectors in smaller earthquakes that concrete block 

support systems performed better than others can be statistically 

proven. .....(p. 14)

Additionally, we have observed the performance of HCD Certified Earthquake Resistant Bracing systems (ERBS) for the first 

time under more than theoretical considerations..... It was observed by inspectors that homes equipped with HCD Certified 

ERBS sustained considerably less than noncertified systems although both types of systems performed adequately. .....(p. 14)

Figure 17 plots the percentage of fallen coaches as a 

function of distance from the fault. Only parks with 25 or 

more coaches were included. The numbers beside the solid 

circles are the same as those found by the park name in 

column 1 of table 31. No strict relationship should be 

drawn between figures 15 and 17 since fault distances are, 

respectively, by ZIP centroid and by park centroid. The 6 

mile boundary for the PML zone remains valid for mobile 

homes in this earthquake.

The department also found two mobile homes destroyed by fire following the earthquake. They may be the 

same as those previously cited for source C.

Dwelling and Mobile Home Monetary Losses Due to the 1989 Loma Prieta, California, Earthquake, with an Emphasis on Loss Estimation B43
Table 31. Mobile home performance in the 1989 Loma Prieta earthquake, insurance and non-insurance data. 

[Data mostly from California Department of Housing and Community Development (1989(?)).]

County and Park Names

SAN BEN I TO COUNTY:

1 Mission Oaks

River Oaks

Hoi lister Park

O'Bannon's

Banning

Country Trailer Estates

Mission Vineyard

Fairview Mobile Manor

SANTA CLARA COUNTY:

2 Pacific Mobile Estates

3 Hacienda Valley

Morgan Hill

4 Wagon Wheel

5 . Madrone Estates

6 Hill Haven

Dalys

SANTA CRUZ COUNTY:

7 Rancho Cerritos

8 Pinto Lakes Estates

9 Monterey Vista

10 Green Valley Estates

11 Colonial Manor

12 Old Mi 1 1

13 Meadow Manor

14 Freedom Mobil ehome

15 Portola Heights

16 Mountain Brook

.17 Vista Del Lago

Riverside

18 Clearview Court

Rancho Corralitos

Totals

Fault 

Dist. 

(mi les)

16.0

-

-

-

-

-

-

18.7

8.8

13.6

-

9.8

13.6

12.5

-

3.3

0.2

3.3

2.8

2.9

5.2

2.1

2.0

2.8

2.6

4.6

3.5

4.4

0.0

Number 

Spaces

225

12

10

11

16

4

7

-

178

165

25

121

173

44

24

144

174

122

105

71

39

276

45

119

44

202

28

50

-

2,434

Coaches 

Fallen

Number

120

8

7

4

2

1

1

-

36

14

12

9

8

2

1

92

82

70

57

8

14

14

13

10

4

1

1

1

-

592

Pet.

53

67

70

36

13

25

14

-

20

8

48

7

5

5

4

64

47

57

54

11

36

5

29

8

9

<1

4

2

-

24

Type of

Steel Piers

Number

75

-

6

-

-

4

-

-

-

-

-

-

-

-

24

33

85

87

36

5

0

10

9

-

-

-

-

-

-

374

Pet. Fell

81

-

100

-

-

100

-

-

-

-

-

-

-

-

4

67

59

69

58

40

-

100

78

-

-

-

-

-

-

64

Vertical Supports for

Concrete Piers

Number

39

-

0

-

-

0

-

-

-

-

-

-

-

-

0

106

73

27

66

49

32

0

31

-

-

-

-

-

-

423

Pet. Fell

46

-

0

-

-

0

-

-

-

-

-

-

-

-

0

64

42

33

53

8

38

0

19

-

-

-

-

-

-

43

Coaches

HCB

Number

111

-

4

-

-

0

-

-

-

-

-

-

-

-

0

5

16

8

3

17

7

266

5

-

-

-

-

-

-

442

Pier

Pet. 

4

1

3

1

2

1

214 

fell

183 

fell

55 

fell
Experience From Previous Earthquakes

Experience from other California earthquakes is first 

summarized by earthquake, followed by an analysis and 

summary of all California experience. Whenever available, 

previously published data have been updated with additional source material.

1971 San Fernando Earthquake

Published loss experience from this magnitude 6.4 

earthquake may be found in Steinbrugge and others 

(1971). Some of the detailed source data for that study is 

no longer extant. Available summary sheets were used in 

these instances.

Table 32 presents the insured loss information gathered from one major insurance carrier. This table is confined to parks where insurance losses were reported and/or 

claims made. Information was not available on policies 

where no claims were made. Loss information was also 

not gathered on parks where no claims occurred. Information was available for 225 coaches out of 4,192 (slightly 

more than 5 percent) in the parks under consideration. No 

information was available on the kind of damage, such as 

that from having fallen from supporting piers. The table 

also shows that this company's market share varied significantly from park to park.

Loss data were examined on 117 out of the 225 insured coaches (52 percent). A $50 deductible applied to 

each policy and therefore claims with losses under this 

amount were usually not submitted and are not included in 

our tabulations. The deductible is much lower than those 

examined for 1987 Loma Prieta and is valuable information in this respect.

70

60

50

40

30

20

10

10 Gr«

98 Pinto La

<

14 Freedoi

13 Mea

7 Rancho

9 Montere 

en Valley Est

;es Estates

> Mobil ehome

 11 Col

 16 Mou 

 5 Mad

low Manor

Cerritos

y Vista 

ites

12 Old Mill

inial Manor

ntain Brook 

 one Estates

m 18 Clean 

^17 Vista

Mew Court 

Del Lago

2 Pacific Me 

(Gilroy)

4 Wagon

bile Estates

Wheel 

6 Hil

1

3 Hacienda 

Haven 5 Ma

lission Oaks . 

(Hollister) '

Valley 

Irone Estates

6 8 10 

DISTANCE FROM FAULT, IN MILES

12 14 16

Figure 17. Loma Prieta earthquake. Percent of fallen mobile homes as a function of distance from the fault. Numbers beside the solid circles are the park numbers identified in 

table 31. Source is California Department of Housing and Community Development 

(1989?, p. 2).

Dwelling and Mobile Home Monetary Losses Due to the 1989 Loma Prieta, California, Earthquake, with an Emphasis on Loss Estimation B45
Table 32. Mobile home loss experience from 1971 San Fernando earthquake, magnitude 6.4.

[Only parks with submitted insurance claims. Loss data provided by one major 

insurance carrier-.]

Insured Loss

Park 

No.

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17/18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

City or 

Community

Chatsworth

Chatsuorth

Chatsworth

Canoga Park

Canoga Park

Canoga Park

Northridge

Northridge

Sylmar

Sylmar

Sylmar

Mission Hills

Mission Hi I Is

Sun Valley

Pacoima

Pacoima

Pacoima

Pacoima

Sun I and

Sun I and

Newhall

Newhall

Saugus

Saugus

Saugus

Saugus

Saugus

Saugus

Saugus

Saugus

Saugus

Saugus

Saugus

Si mi Valley

Totals

Park Name

Indian Hills

Chatsworth

Imperial Gardens

Canoga Country

Kona Kai

Eaton

Walnut

Northridge

Tahiti an

Sylmar

Lumark

Monterey Manor

Mission Manor

Laurel Canyon

Shelter Isle

Shadow Hills

Blue Star/Mission

Skyland Terrace

Sherman Grove

Monte Vista

Mulberry Park

Polynesian

Parklane

Cordova

Granada Villa

Desert Gardens

Sierra Trailer

Royal Oaks

Caravilla

Blackburns

Sand Canyon

Canyon Breeze

Lilly of Valley

Santa Susana

Total 

Coaches 

In Park1

138

198

184

155

116

111

62

168

175

66

101

71

95

60

260

96

240

69

76

71

108

144

330

280

92

60

76

85

84

50

70

90

112

99

4,192

Insured 

Coaches 

In Park

8

14

12

12

11

12

4

12

1

1

4

10

9

3

6

2

3

1

3

5

8

6

26

9

2

3

3

5

7

2

2

4

10

5

225

Data

Coaches 

With Loss 

Over $50

1

2

4

3

5

3

1

9

1

1

4

7

6

1

3

2

1

1

3

2

2

4

17

8

2

3

3

5

4

1

2

2

3

1

117

Average 

Percent 

Loss

0.0

1.6

6.7

3.2

3.6

2.0

6.6

5.2

30.0

25.4

19.7

8.0

19.8

11.3

7.7

5.4

13.5

39.1

3.5

11.6

7.0

14.6

20.1

23.1

7.4

7.8

8.6

9.9

9.9

7.5

8.3

0.0

8.5

2.1

on the number of spaces available for mobile homes. Parks are normally 

at or close to capacity. As a result, the number of coaches are 

slightly overstated for some parks.

Earthquake bracing in any form was very rare.

Figure 18 shows the locations of all but two of the 

mobile home parks for which loss data were available; 

park 35 in Simi Valley is slightly west of the map boundary, and the other park (not listed in table 32) is in Gardena, about 35 miles from the source of the earthquake's 

energy, where a 24 percent loss occurred to one of fifty 

coaches. Undoubtedly there were many mobile home 

parks between 10 miles (park 35 in Simi Valley) and 35 

miles (Gardena) with very small damage and no reported 

insurance claims. The Gardena loss was not considered to 

be meaningful and was not included in further study.

Thrust faulting, such as that which occurred during 

the 1971 San Fernando earthquake, creates ground fractures and other surface disturbances over a wide zone 

(Barrows and others, 1973; Steinbrugge and others, 1971). 

Ground fractures and displacements scattered intensified 

damage to wood frame dwellings as shown in figure 14 of 

Steinbrugge and Algermissen (1990). They also intensified 

damage in the mobile home tracts.

Figure 19 plots percent losses against distance from the 

earthquake's energy source. The loss in the percent loss 

computations includes a $50 deductible. The park's distance 

is not from the epicenter, but rather from the energy release

B46 Estimation of Earthquake Losses to Housing in California
at depth along the fault rupture. The San Fernando thrust 

fault dips about 45 degrees to the north from its poorly 

defined surface expression in the San Fernando Valley. The 

focal depth of the earthquake was about 8 kilometers beneath the epicenter shown in figure 18. The model for the 

location of the energy release is a line source on the 45- 

degree fault plane, at a depth midway between the focus and 

the generalized surface expression of the fault. The horizontal length and strike of the line source is taken to be the same 

as the generalized surface expression of the fault. The San 

Fernando model is similar in concept to 1989 Loma Prieta 

in figure 2.

Mobile home parks in figure 18 were separated into 

three groups: (1) those on the upper plate of the thrust

fault, (2) on the lower plate, and (3) on the ground disturbed areas on maps (Barrows and others, 1973; Steinbrugge and others, 1971). Figure 14, Steinbrugge and 

Algermissen (1990), shows portions of the same area 

where damage can be identified with ground disturbances.

In figures 18 and 19, parks numbered 9, 10, 11, 17, 

18, and 19 are close to the faulting and had abnormally 

high losses (table 32). Disturbed ground conditions were 

also a factor. Park 19 had significant faulting across the 

rear portion of the park. Park 11 was very close to faulting. Losses at these parks do not qualify under the PML 

definition since the damage was not due to shaking alone.

Thirteen parks in Newhall and Saugus are on the 

upper plate and away from the disturbed areas. Nine of the

San Fernando earthquake, 

major segment of the 

faulting, highly generalized.

Figure 18. 1971 San Fernando earthquake region showing the locations of mobile home parks. Numbers 

adjacent to the solid triangles are park numbers found in table 32.

Dwelling and Mobile Home Monetary Losses Due to the 1989 Loma Prieta, California, Earthquake, with an Emphasis on Loss Estimation B47
thirteen are concentrated in a 4 mile stretch along, or close 

to, the Soledad Canyon Road. This road closely follows 

the Santa Clara River. Park 25, in a former flood plain of 

this river, sustained abnormally high losses, an average of 

23 percent per unit. Several of the nine parks near the 

Santa Clara River were located on the unconsolidated 

gravels and sands of its flood plain. Nearly 95 percent of 

the coaches were shaken off their supports in park 26, 

while park 24, about a mile and a half away, experienced 

displacement of 280 coaches. It is likely that soil conditions increased the losses, similar to Mission Oaks Park in 

the 1989 Loma Prieta earthquake (table 26).

Observations on San Fernando

Figure 19, a plot of losses versus fault distance, is of 

interest for the loss attenuation component in loss estimation programs. This will be further examined in a following section.

Table 33 shows a loss breakdown by construction components as a percentage of value. Excluded are coaches 

located in disturbed ground areas and parks with incomplete 

loss breakdowns. This kind of information is useful for 

visual loss estimation purposes during field inspections.

Three mobile home parks (9,10,11) were adjacent to or 

in areas where losses for conventional dwellings have been 

determined see figure 18 herein along with figure 14 in 

Steinbrugge and Algermissen (1990). The right hand column 

in table 34 is the ratio between the average loss for mobile 

homes to wood frame dwellings. These ratios indicate that a 

San Fernando type earthquake may produce 2 to 4 times 

more damage to a mobile home than to a conventional wood 

frame dwelling in the more heavily shaken areas. These 

comparisons are at zero deductible, that is, at PML values.

45

40

35

30

25

20

15

10

23 ^

9

10 

O

k

O

11

O 17/18 

<

A

16 

20 

25A

13 '

'21

* 27* 

22 26*

 A 

1 24

32 

12 A

33

« D1st

0 in t 

. Lowe

(San

A U PPC

A (Sau

14 

A

31 3* <

<

1

urbed ground and/or 1 

he near vicinity.

r plate of thrust fai 

Fernando Valley)

r plate of thrust fai 

gus and Newhall)

>7 

8

 2

A 34

*4

 5

Suiting 

Jit

lit

< 35

O 

QL

O

Z3 

O

O

ot.

>- 

_l 

_l

<

00

00

LU

00 

00 

O

345678 

DISTANCE FROM SEISMIC ENERGY SOURCE, IN MILES

10 11

Figure 19. 1971 San Fernando earthquake. Percent loss over deductible as a function of distance for individual mobile 

home parks. Numbers are park numbers identified in table 32.

B48 Estimation of Earthquake Losses to Housing in California
Table 33. Average loss to mobile home components, 1971 San Fernando earthquake, magnitude 6.4.

[Losses at zero deductible as a percentage of insured value. Adapted from table 1. Steinbrugge 

and others (1980).]

Loss, in

District or

Community

Sylmar

Sun I and

San Fernando

Pacoima

Newhall

Mission Hi Us

Saugus

Northridge

Canoga Park

Chatsworth

Number

Insured

Coaches

8

8

17

6

40

10

45

16

35

34

Number

Paid

Claims

6

5

15

3

23

7

30

10

10

5

Coach 1

18.4

1.2

4.8

3.2

4.4

3.9

5.1

1.5

0.5

1.2

Awning

and

Skirt

3.8

2.5

1.4

0.3

2.6

1.8

1.9

1.2

0.3

0.0

Pet. of Insured Value

Re I eve I

3.8

0.9

1.4

1.9

2.5

1.7

1.6

1.1

1.0

1.1

Contents

5.9

1.4

2.0

1.8

3.1

1.3

3.3

0.9

1.3

0.9

Total

31.9

6.0

9.6

7.2

12.6

8.7

11.9

4.7

3.1

3.2

Modified

Mercalli

Intensity2

X

VII

X

VII

VIII

VIII

VIII

VII

VI

VI

Totals 219 

Weighted average

114

2.3 0.9 0.9 1.3 5.4

excluding awing, skirt, and contents. 

Then NOAA publications, now USGS.

Table 34. Wood frame dwelling versus mobile home losses for 1971 

San Fernando earthquake, magnitude 6.4, zero deductible.

Average Percent

Park

No.

9

10

11

In or Adjacent to

Tracts in Figure 141

10, 18

18, 21, 30

33, 43

Loss per

Dwellings

6.9

5.7

8.7

Unit

Mobile

Homes2

30.0

25.4

19.7

Ratio --

Mobi le Homes

To Dwellings

4.3

4.5

2.3

Steinbrugge and Algermissen (1990). 

2$50 deductible added to insured loss.

1978 Santa Barbara Earthquake

Loss experience on eight mobile home parks from 

this magnitude 5.1 earthquake is found in Steinbrugge and 

Schader (1979), summarized as follows:

Number of mobile homes

In 8 parks

With reported damage 

With earthquake insurance 

With paid claims

1,392

476

1,344

118

Locations of the mobile home parks (solid triangles) 

and the earthquake epicenter are shown in figure 20.

Most of the claims and insurance policies had a mandatory deductible of $350 to be applied to the aggregate

loss of coach and contents. Additional living expense losses 

were very seldom encountered and were not included in 

this examination. A few of the claims had a one percent or 

$250 deductible, whichever was greater; in each case, the 

deductible amount was included in the analysis. When a 

claim was made and the loss did not reach the deductible, 

the claim data were not included in the tabulations.

Loss information was available on 35 percent (494) of 

the mobile homes of which 24 percent (118) had losses over 

the deductible (see table 35). Not included were claims with 

incomplete information. The $250 and $350 deductibles for 

1978 Santa Barbara were higher than the $50 deductible for 

1971 San Fernando, thereby reducing the comparative data 

quality for the lesser losses. These lesser losses increased 

for 1989 Loma Prieta because of its 10 percent deductible.

None of the Santa Barbara parks were located in 

ground disturbed areas or in fault zones. On the other

Dwelling and Mobile Home Monetary Losses Due to the 1989 Loma Prieta, California, Earthquake, with an Emphasis on Loss Estimation B49
Table 35. Average loss to mobile home components from 1978 Santa Barbara earthquake, magnitude 5.1.

[Loss at zero deductible as a percentage of insured value. Data supplied by two major insurance carriers. Adapted from 

table 1 of Steinbrugge and Schader (1979).]

Analyzed as Part of This Study

Park 

No.

1

2

3

4

5

6

7

Dist. to

Epicenter 

(mi.)

6

6

6

6

7

10

11

Mobile

Homes 

In Park

234

332

150

105

200

225

146

Total 

Insured

Mobile 

Homes1

230

330

145

100

198

200

141

Loss, in Pet. of Insured Value

Insured

Mobile 

Homes

48

173

64

51

52

45

61

Number

Paid 

Claims

16

11

13

4

12

12

50

Coach2

2.1

0.7

1.0

3.1

0.8

2.8

1.7

Awning

and 

Skirt

0.3

0.6

1.3

1.5

0.4

1.4

1.2

Re I eve I

1.6

0.6

2.1

0.9

1.0

2.2

1.7

Contents

0.7

2.2

0.7

0.5

1.7

0.5

1.1

Total

4.6

4.1

5.1

6.0

3.9

7.1

5.7

Modified

Mercalli 

Intensity3

VII

V

V

VI

VI

V

V

Totals 1,392 

Weighted average

1,344 494 118

1.7 1.0 1.6 1.1 5.4

Determined by park manager. See next column for mobile homes included in this study. 

2Coach, excluding awning, skirt, and contents. 

Determined by the authors for each park site.

hand, soils at some parks did vary considerably from those ratio of paid claims to existing policies, yet the average 

found in other parks as did the topography. This may ex- loss for the park was not the highest, 

plain why park 6 at nearly the farthest distance from the The earthquake's small magnitude of 5.1 indicates a 

epicenter had the highest losses much more than those at small horizontal rupture length. The epicenter was therehalf the distance. It is not clear why park 7 had the highest fore used as a point source for seismic energy. As a result,

PACIFIC OCEAN

34° 

22'30"

SCALE, IN MILES

EPICENTER

119°|52'30" 119°|45'

Figure 20. 1978 Santa Barbara earthquake region showing epicenter and approximate location of the mobile home 

parks (solid circles). Numbers beside the circles are identified in table 35.

B50 Estimation of Earthquake Losses to Housing in California
Table 36. Average loss to mobile home components from 1979 El Centre (Imperial Valley) earthquake, magnitude 6.4.

[Losses at zero deductible as a percentage of insured value. Adapted from table 3. Steinbrugge and others 

(1980).]

Analyzed as Part of This Study

Approx.

Dist. to

Park Epicenter

No. (mi.)

1 4.5

2 2.5

33 1<?>

Totals

Weighted average

Total

No. of

Mobile

Homes

116

117

85

318

No. of

Damaged

Mobile

Homes 1

79

100

76

255

Loss, in Pet. of Insured

No. of

Claims

Studied

14

18

5

37

Coach2

2.6

2.2

1.4

2.4

Awning

and

Skirt

2.3

2.0

1.4

2.1

Re I eve I

1.8

1.9

2.6

1.9

Value

Contents

2.8

1.0

0.0

1.8

Total

9.5

7.1

5.4

8.2

Modified

Mercalli

Intensity

VI 1+

VII+

VII+

Defined as the number of coaches where reIeve I ing was required. Assessment made by authors. 

2Coach, excluding awning, skirt, and contents. 

3Data questionable, and not included in weighted average.

Figure 21. 1979 El Centre earthquake region showing mobile home parks (solid triangles). Numbers by the triangles 

are park numbers identified in table 36.

distances to the epicenter were used instead of fault distances in table 35.

Observations on Santa Barbara

No loss attenuation relationships are possible since 

four of the seven parks were in the PML zone and the 

three remaining are close to the zone boundary.

Table 35 losses to 1978 Santa Barbara coach components should be examined in the context of table 33 (San 

Fernando components), thereby improving loss estimation 

techniques. Similar information will be presented for the 

1979 El Centro earthquake.

1979 El Centro (Imperial Valley) Earthquake

Loss experience for three mobile home parks in this 

magnitude 6.4 earthquake is found in Steinbrugge and others (1980). Figure 21 shows the locations of these parks 

with respect to the generalized surface traces of the faulting. Extensive damage occurred in these parks. As usual, 

observed wood frame dwelling damage was comparatively 

much less.

At the time of the earthquake, insurance policies had 

a deductible of $250 for the coach (which included losses 

to skirts, awnings, and the cost to relevel) and a separate 

$250 deductible for contents losses. All losses in table 36 

were adjusted to a zero deductible, consistent with table 

35 (Santa Barbara) and table 33 (San Fernando).

The then recently constructed park 1 (Gio's) was located in El Centro on Lincoln Avenue and a little more 

than one mile northwest of downtown El Centro. It was 

approximately 4.5 miles southwest of the faulting. There 

were 116 coaches in the park: 88 double-wide and 28 single-wide, some with add-on units.

Dwelling and Mobile Home Monetary Losses Due to the 1989 Loma Prieta, California, Earthquake, with an Emphasis on Loss Estimation B51
Park 2 (KOA Country Life) was also of relatively new 

construction. There were 117 new coaches, all appearing to 

be supported on steel piers. The park contained 49 doublewide and 68 single-wide coaches. The park's location was 

east of El Centro on Ross Road near State Route 111. This 

location is approximately 2.5 miles southwest of the fault 

trace. Despite apparent severe shaking, pavements and concrete parking slabs in the park were undamaged. Nearby 

wood frame dwellings appeared undamaged.

Park 3 (Tangerine Gardens), with 85 coaches, was located 3 miles south of downtown Brawley on Legion Road. 

It consisted of 42 double-wide and 43 single-wide coaches, 

with some being older than those found in the other parks. 

The location was approximately 1 mile northwest from a 

zone of fresh cracking on a pre-existing fault scarp.

Table 36 is similar to table 33 for San Fernando and 

to table 35 for Santa Barbara. Previous comments also 

apply here.

Test of Rapid Loss Estimation, El Centro

The time necessary to acquire loss data from insurance sources is very long and the process can be tedious. 

There is usually a long wait during the insurance adjustment period, including the settlement of difficult claims, 

and the company's processing time toward the last completed and closed claim. It is often desirable to make a 

quick postearthquake field survey of damage to develop an 

estimated aggregate loss.

A pilot method used for this earthquake was a word 

grading system which summarized observed damage and 

assigned percentage losses to these word gradings. The definitions of degrees of damage are found in Appendix B, and 

these definitions can be supplemented by representative 

photographs. The observed damage to skirt and awnings, 

coaches off or partially off supports, and needs for releveling were quickly determined. The location of coaches in 

each park can be noted by space numbers usually available 

from the park manager's coach location map. This check 

allowed for future correlation with adjusters' information.

All coaches in the three parks in table 36 were externally inspected using the damage descriptions in Appendix 

B. Insurance loss data were then correlated with field observations in all three parks. Damage descriptions in Appendix B showed in table 37 the relationships to percent

Table 37. Mobile home damage from 

1979 El Centro (Imperial Valley) earthquake, magnitude 6.4.

Coach damage

None

Slight

Moderate

Severe

Number of 

Coaches

3

6

5

23

Percent 

Loss

2.2

2.4

5.0

10.8

loss. The column "Percent Loss" is based on insurance 

loss (including contents) to insured value. Where there 

was no observed coach damage, any loss would be due to 

contents falling.

1980 Livermore (Greenville) Earthquakes

Two mobile home parks were in the more heavily 

shaken area of two earthquakes which occurred one day 

apart. Figure 22 is a vicinity map showing the location of 

these parks and also the approximate locations of some of 

the ground breakage associated with possible faulting. 

"The surface faulting was discontinuous .... and in places 

was difficult to separate from downslope gravity movements .... and may have extended as far as the vicinity of 

Interstate Highway 580... "(Bonilla and others, 1980, 

p. 15). Magnitudes were, respectively, 5.5 and 5.6. Park 1 

(Sunrise) was located northeast of Livermore and immediately north of Interstate 580 in the community of Springtown. Every coach was exterior inspected in accordance 

with the methods given in Appendix B. Damage of some 

kind was almost universal to the coaches. Insured values 

were obtained from insurance sources, but no followup 

was made to obtain the results of adjusted claims. A summary of the field inspections is given in table 38.

Park 2 (Vineyard Mobile Villa), located 3 miles west 

of park 1 and also on Interstate 580, received no damage 

to any of its 159 coaches mostly single-wide. Park occupants reported 5 to 10 percent of their shelf items fell. The 

damage contrast between these two parks was remarkable 

and was not attributed to construction.

Two story wood frame apartment houses adjacent to 

park 1 were interior and exterior inspected for comparison

Figure 22. 1980 Livermore (Greenville) earthquake region 

showing approximate location of surface breakage associated 

with faulting. Numbers by the solid triangles are park numbers identified in the text.

B52 Estimation of Earthquake Losses to Housing in California
Table 38. Mobile home damage in park 1 from 1980 Livermore 

(Greenville) earthquakes, magnitudes 5.5 and 5.6.

[Summary of field inspections using Appendix B damage classifications.]

Number Coaches

Type of

Single-wide

Double-wide

Single-wide

Double-wide

Triple-wide

coach

w/ expansion

w/expansion

None

4

1

0

1

0

Having

Slight Moderate

6

14

4

0

0

5

10

5

0

0

Damage:

Severe

19

57

6

0

1

Total 

Coaches

34

82

15

1

1

Totals 24 20 83 133

Table 39. Mobile home damage from 1983 Coalinga earthquake, 

magnitude 6.7.

[Summary of field inspections using Appendix B damage classifications.]

Number Coaches Having

Type of

Single-wide

Double- wide

Single- wide

coach

w/expansion

None

4

1

2

Slight

7

1

2

Moderate

7

2

18

Damage:

Severe

38

2

0

Total

Coaches

56

23

22

Totals 10 27 40 101

Table 40. Performance of mobile home supports in 1983 Coalinga earthquake, magnitude 6.7.

[Type of coach support versus coach stability.]

Vertical Supports

Did 

Coach Shift 

Or Fall?

Yes

No

Metal 

Piers

71 (92%) 

6 (8%)

Wood 

Blocks

0 

2

Hollow 

Concrete 

Blocks

14 (56%) 

11 (44%)

with the mobile home damage. No exterior damage was 

noted to the apartment houses. Very slight movements on 

interior gypsum board joints were found in some instances. 

Occupants and the apartment managers estimated that 30 to 

50 percent of the shelf items fell when not in cabinets. Lamps 

were knocked over. Electric water heaters shifted, breaking 

flexible water hose connections. All windows in the eight 

buildings housing a total of 42 units were unbroken.

Within a quarter mile west of park 1, 60 percent of 

the shelf stock fell at an undamaged liquor store. There 

were several statements after the event that the earthquake 

stability of the unbraced mobile homes was little more 

than that of stock on shelves!

The Lawrence Livermore Laboratory reported the 

following for their coach units which were structurally 

similar to mobile homes:

.....[there were] approximately 975 individual trailer [coach] units

organized into 216 complexes. At the time of the earthquake, 87 

of these complexes had a lateral force tiedown system. In general, 

there was very little damage to trailers. In complexes not tied 

down, one trailer was badly damaged (walls cracked, etc.) and 

four were moderately damaged (interior ceiling tiles and light fixtures were displaced). Some complexes moved slightly and some 

foundations jacks fell...... However, no. structural damage occurred

to trailers that were tied down..... (Lawrence Livermore Laboratory, 1980, p. 20).

The laboratory is about 2 to 3 miles south of the 

poorly established southern end of the surface expression 

of faulting.

1983 Coalinga Earthquake

The one mobile home park in Coalinga experienced a 

nearby earthquake having a magnitude of 6.7 and a Modified Mercalli intensity of VIII. This intensity applied to the 

city as well as to the park. The park was located in the 

eastern section of the city, adjacent to Olson Park, and 

south of Roosevelt Avenue (Steinbrugge, Fowkes, and others, 1990, p. 360). Coaches were field inspected for (a) 

width (single-wide, double-wide, and single-wide with expansion units), (b) whether or not the coach fell or shifted 

on its supports, (c) type of supports (metal piers, hollow 

concrete block, wood, or other), (d) damage to skirt, (e) 

damage to coach, and (f) add-on porch (if any) and its 

separation from the main unit. Damage evaluations were 

made using the criteria found in Appendix B.

Information from the field inspections is found in table 

39. Unfortunately, insurance losses were not obtained, and 

thus correlations between observed damage and actual 

losses are not available. Field survey data were complete for 

101 of the 105 units in the park, summarized in table 39.

Dwelling and Mobile Home Monetary Losses Due to the 1989 Loma Prieta, California, Earthquake, with an Emphasis on Loss Estimation B53
Table 41. Mobile home loss over deductible in PML zone. 

[Limited to coaches with paid losses.]

Percent Loss Over Percent Deductible

Loma Prieta Watsonville Loma Prieta PML 1971 

PML Zone ZIP 95076 Excl. ZIP 95076 San Fernando 

MAG = 7.1 MAG = 7.1 MAG = 7.1 MAG = 6.4 

263 Coaches 81 Coaches 182 Coaches 70 Coaches

Pet. 

Ded.

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

Coach Coach-*- Coach Coach* Coach Coach* Coach* 

Only Conts. Only Conts. Only Conts. Conts.

... .

... .

... .

... .

... .

... .

... .

... .

... .

. . .

. . .

 . .

. . .

. . .

. . .

. . .

. . .

. . .

m m

, ,

f f

m 9

m u

. .

^ u

, ,

. .

4.67 1.43 7.88 2.06 3.38 1

4.32 1.31 7.24 1.87 3.15 1

4.01 1.20 6.69 1.68 2.94 1

11.27

10.59

9.90

9.23

8.61

8.02

7.46

6.94

6.44

5.98

.17 5.53

.08 5.08

.01 4.65

3.74 1.11 6.17 1.53 2.76 0.94 4.27

3.49 1.04 5.69 1.42 2.61 0.88 3.94

3.27 0.97 5.26 1.33 2.47 0.82 3.64

3.05 0.91 4.85 1.24 2.33 0.77 3.36

2.86 0.85 4.51 1.16 2.19 0.73 3.12

2.68 0.80 4.20 1.09 2.07 0.68 2.90

2.53 0.74 3.94 1.03 1.96 0.63 2.70

2.39 0.69 3.69 0.96 1.86 0.58 2.51

1978 

Santa Barbara 

MAG = 5.1 

56 Coaches 

Coach* 

Conts.

1.18

1.02

0.86

0.71

0.57

0.45

0.35

0.27

0.21

0.17

0.13

0.11

0.09

0.07

0.06

0.06

0.05

0.04

0.04

0.03

0.02

The kinds of vertical supports for the coaches were 

compared with damage in table 40. This comparison suggests that hollow concrete block supports performed better 

than steel piers. This was strongly confirmed in the 1989 

Loma Prieta earthquake where 64 percent of coaches on 

steel piers fell while only 12 percent with hollow concrete 

block supports fell (table 31).

Synthesis and Overview

To this point, partial analyses and findings have been 

made by individual earthquakes. In this section, these are 

synthesized and organized by subject rather than by 

earthquake.

PML Zone

The 6 mile (10 kilometer) boundary of the PML zone 

from the surface projection of the line source of the earthquake energy is a reasonable model for mobile homes (figures 15, 16, and 17) as well as for wood frame dwellings. 

The model uses the average of all losses in the PML zone, 

excluding geohazards; this average is the PML, expressed 

in percent or in dollars. It is likely that this model will be 

substantially changed and improved when better near-field 

loss and seismic data are eventually obtained.

Loss Over Deductible in the PML Zone

As is the case for wood frame dwellings, determining 

the loss over deductible for the PML zone has two necessary requirements. The value of each mobile home in the 

entire study area (or insurance company's book of business) must be known, whether a mobile home suffered 

losses or not. Second, the losses and deductibles, if any, 

must be known for each mobile home. The first criteria is 

met by all mobile homes included in table 41. Only data 

from the 1971 San Fernando and the 1978 Santa Barbara 

earthquake come adequately close to satisfying the second 

criteria with their average deductibles of 0.2 percent and 

1.2 percent, respectively. In these latter two cases, the dollar deductible was very low, being $50 for 1971 San 

Fernando and $250 or $350 for 1978 Santa Barbara.

Unfortunately, the 1979 Santa Barbara loss over deductibles may be incorrect by a large amount. At the damage 

threshold of magnitude 5, experience indicates that the 6 

mile PML boundary is too large. The Santa Barbara parks 

are at this 6 mile boundary and these data are not used.

With few variants, mobile home loss over deductible 

analysis follows that for wood frame dwellings. Table 41 

shows all known loss over deductible information. Analysis was restricted to the 1989 Loma Prieta PML zone (columns 2 and 3) and to the 1971 San Fernando experience 

(column 8). The Loma Prieta PML zone was chosen for

B54 Estimation of Earthquake Losses to Housing in California
Table 42. Loss over deductible as a function of deductible, in percent. 

[Uncertainty factor « 1. Applicable to mobile home coaches, excluding contents.]

Percent 

Deducti bl e

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

Magnitude

5.00

0.50

0.46

0.43

0.40

0.37

0.34

0.32

0.29

0.27

0.25

0.23

0.21

0.20

0.18

0.17

0.16

0.15

0.14

0.13

0.12

0.11

5.25

1.61

1.49

1.38

1.28

1.19

1.10

1.02

0.94

0.87

0.81

0.75

0.69

0.64

0.59

0.55

0.51

0.47

0.44

0.40

0.37

0.35

5.50

2.73

2.52

2.34

2.16

2.00

1.86

1.72

1.59

1.47

1.36

1.26

1.17

1.08

1.00

0.93

0.86

0.80

0.74

0.68

0.63

0.59

5.75

3.84

3.55

3.29

3.05

2.82

2.61

2.42

2.24

2.08

1.92

1.78

1.65

1.53

1.41

1.31

1.21

1.12

1.04

0.96

0.89

0.83

6.00

4.95

4.58

4.25

3.93

3.64

3.37

3.12

2.89

2.68

2.48

2.30

2.13

1.97

1.82

1.69

1.56

1.45

1.34

1.24

1.15

1.07

6.25

6.06

5.61

5.20

4.82

4.46

4.13

3.82

3.54

3.28

3.04

2.81

2.60

2.41

2.23

2.07

1.92

1.77

1.64

1.52

1.41

1.30

6.50

7.18

6.65

6.15

5.70

5.28

4.89

4.53

4.19

3.88

3.59

3.33

3.08

2.85

2.64

2.45

2.27

2.10

1.94

1.80

1.67

1.54

6.75

8.29

7.68

7.11

6.58

6.10

5.64

5.23

4.84

4.48

4.15

3.84

3.56

3.30

3.05

2.83

2.62

2.42

2.25

2.08

1.93

1.78

7.00

9.40

8.71

8.06

7.47

6.91

6.40

5.93

5.49

5.08

4.71

4.36

4.04

3.74

3.46

3.21

2.97

2.75

2.55

2.36

2.18

2.02

7.25

10.51

9.74

9.02

8.35

7.73

7.16

6.63

6.14

5.69

5.27

4.88

4.52

4.18

3.87

3.59

3.32

3.08

2.85

2.64

2.44

2.26

7.50

11.63

10.77

9.97

9.23

8.55

7.92

7.33

6.79

6.29

5.82

5.39

4.99

4.62

4.28

3.97

3.67

3.40

3.15

2.92

2.70

2.50

7.75

12.74

11.80

10.92

10.12

9.37

8.68

8.03

7.44

6.89

6.38

5.91

5.47

5.07

4.69

4.35

4.02

3.73

3.45

3.20

2.96

2.74

8.00

13.85

12.83

11.88

11.00

10.19

9.43

8.74

8.09

7.49

6.94

6.42

5.95

5.51

5.10

4.72

4.38

4.05

3.75

3.47

3.22

2.98

8.25

14.96

13.86

12.83

11.88

11.01

10.19

9.44

8.74

8.09

7.49

6.94

6.43

5.95

5.51

5.10

4.73

4.38

4.05

3.75

3.48

3.22

analysis over the Watsonville study area since geohazards 

were not as important for mobile homes as they were for 

wood frame dwellings. The 1971 San Fernando losses 

over deductible data are for coach plus contents; 1989 

Loma Prieta breaks these down by coach and by coach 

plus contents. Plotting normalized coach plus contents 

data for Loma Prieta (column 3) and San Fernando (column 8) showed a good match. As a consequence, the 

shape of the San Fernando curve was used for Loma Prieta. From there on, the methods used for wood frame 

dwellings were largely followed.

The San Fernando loss over deductible equation is 

based on column 8 of table 41:

San Fernando coaches plus contents: 

LD = 11.65912 e-°-0768237D 

where 

LD = percent loss over deductible, and

D = deductible in percent.

The variables have the same meaning as those for wood 

frame dwellings. The equations for the Loma Prieta earthquake become:

Loma Prieta coaches:

LD = 9.845945 e-°-0768237 D (9) 

and

Loma Prieta coaches plus contents: 

LD = 3.014925 e-°-0768237 D (10)

Next including a variable magnitude and a user-selected 

uncertainty factor as was done for wood frame dwellings:

Coaches only, for general use:

LD = [4.450450 (M - 5) + 0.5] e-°-0768237 D 

where

M = magnitude, and 

F = user-selected uncertainty factor, 

and for:

Coaches plus contents, for general use:

LD = [1.197583 (M - 5) + 0.5] e-°-0768237 D

xF (11)

x F (12)

where LD may be user-limited to magnitude 7.75 in equations 11 and 12.

Table 42 shows loss over deductible as a function of 

the deductible in 0.25 percent increments for coaches only. 

This a counterpart to table 15 for wood frame dwellings.

Figure 23 graphically shows the loss over deductible 

for coaches and for coaches plus their contents. These 

curves are for a magnitude 7.75 earthquake.

Maximum Losses in the PML Zone

Table 43 shows maximum losses for four earthquakes, with differing magnitudes for three of them. The 

average loss for the upper 10 percent of mobile homes decreases with decreasing earthquake magnitude column 4 

of table 43.

With rare exception, individual coach plus contents 

losses before the deductible are not expected to exceed 2/3 

of their combined values when ensuing fire and geohazards are excluded.

Dwelling and Mobile Home Monetary Losses Due to the 1989 Loma Prieta, California, Earthquake, with an Emphasis on Loss Estimation B55
Table 43. Comparison of losses to mobile homes.

[Data restricted to mobile homes in parks located in the PML zone, but 

excluding those in the geohazard areas (ground disturbed areas) of the 

1989 Loma Prieta and 1971 San Fernando earthquakes. Also excluded are 

losses due to ensuing fire.]

Highest 10 Pet. of Mobile 

Homes with Losses Highest

Earthquake Magnitude

1989 Loma Prieta

1971 San Fernando

1979 El Centre

1978 Santa Barbara

7.1

6.4

6.4

5.1

Number of 

Mobile Homes

13

6

4

6

Average 

1 Pet. Loss2

37.0

36.6

22.3

19.9

Single 

Pet. Loss

60.3

50.4

26.0

33.4

J 10 percent of total.

2 Loss to coach and contents (before deductible) divided by insured

value for every mobile home, then the highest 10 percent

of mobile home losses are averaged.

It has been previously shown from source B mobile 

home data for Loma Prieta that contents losses as a percent of contents values are not likely to exceed 50 percent 

when geohazards and fire following are excluded.

Loss Attenuation with Distance

Information on loss attenuation with distance is incomplete and the discussion which follows has limited 

utility. Figures 15 and 17 show very few loss data beyond 

the 6 mile PML boundary. While loss attenuation with distance is apparent, its quantification in equation format 

poses difficulties. Figure 15 is based on a 10 percent de15

10

00

00

o

0 5 10 15 

DEDUCTIBLE, IN PERCENT

Figure 23. Percent loss over deductible as a function of 

percent deductible. Curve for coaches is based on equation 

11 for magnitude 7.75. That for coach and contents is based 

on equation 12, also for magnitude 7.75.

ductible, and quantification at zero deductible is questionable. Figure 17 is based on fallen coaches and is not 

monetarily quantified.

Within the PML zone, there is some Loma Prieta evidence of loss attenuation between Watsonville and the 

coastal communities of Capitola, Aptos, and Soquel (see 

fig. 15). Six of the seven parks in the Watsonville ZIP 

were located about 2.5 miles from the fault, and the seventh was approximately on the fault. Fifteen others outside 

of this ZIP and in the PML zone were 4 to 6 miles from 

the fault, mostly in the coastal Capitola-Aptos-Soquel 

area. All source B mobile home parks in the PML zone 

were inspected for major geohazard losses and none were 

found. A reasonable inference is that losses in the PML 

zone were not uniform and decreased with distance from 

the fault.

Figure 16 shows each park's losses and its distance 

from the fault. The data for this figure provides a better 

approach despite the mentioned limitations. We prefer a 

logarithmic equation for loss attenuation since it is consistent with most strong motion attenuation curves. An alternate straight line equation is also given:

Logarithmic:

LD at 10% deduct. = 2.78897 e-°- 16566 x (13)

Straight line:

LD at 10% deduct. = 2.78897 - 0.16566 X (14)

where X is the distance in miles. These equations apply 

only for the Loma Prieta magnitude and for a 10 percent 

deductible.

The 1971 San Fernando earthquake provided the only 

other usable information on loss attenuation with distance 

from the fault (see fig. 19 and table 32). Various attenuation equations were examined from the standpoints of (a)

B56 Estimation of Earthquake Losses to Housing in California
straight line versus exponential, (b) with or without the 

inclusion of parks located in the disturbed ground areas, 

(c) contiguous parks combined into one data entry, and 

other possibilities. It appears that a straight line function 

which excludes the parks in disturbed areas and also combines contiguous parks will best represent reality up to 10 

miles from the surface projection of the line source of 

seismic energy:

LD = 16.2986 - 1.3853 X (15)

where X is the distance in miles. This equation applies 

only to the San Fernando earthquake with its essentially 

zero deductible.

Earthquake Bracing

It is clearly evident that earthquake bracing systems 

are very effective. State certified systems have performed 

excellently, and none have been known to fail. There is no 

reason to believe that older pre-certification systems are 

necessarily inferior, but a qualified person such an engineer should be the judge.

When no earthquake bracing is present, steel piers 

which support a coach are more likely to allow coach toppling than other types. On the other hand, steel piers as 

well as other types of vertical supports are expected to 

perform well upon installation of a certified earthquake 

bracing system, or equal as many seemed to be.

Coach Size and Damage

Coaches may be classified by size such as singlewide, double-wide, triple-wide, and with variants. Loma 

Prieta experience from 258 coaches showed that singlewide coaches performed marginally better than did two- or 

multiple-wide. The comparison was made on an average 

coach plus contents loss basis (7.0 and 7.8 percent, respectively). In the 1980 Livermore earthquake (table 38), single-wide performed better than double-wide "severe" 

damage. The reverse was true for the 1983 Coalinga earthquake (table 39). No doubt, the type of coach supporting 

piers is more important than coach size for unbraced 

coaches, but correlation data were unavailable.

No conclusions can be drawn from this mixed experience on coach size.

Loss Estimation From Rapid Field Inspections

The length of time needed to acquire insurance loss 

information may be excessive for many disaster response 

activities. The concept of a rapid field inspection introduced 

after the 1979 El Centro earthquake has promise. See tables 

33 and 35 for information useful for field investigations.

The methodology has not gone beyond the pilot 

stage.

SUMMARY, MAJOR FINDINGS, AND 

CONCLUSIONS

Wood Frame Dwellings

Dwelling Loss Versus Other Losses

Within the nine county study area (fig. 1), wood 

frame dwelling losses amounted to 18.5 percent of the insured economic loss (table 1). Clearly, wood frame dwelling losses did not dominate over those to commercial and 

industrial properties.

In social and political senses, dwelling losses and 

dwelling habitability are of great importance to the general 

public, to disaster response entities such as the Red Cross, 

and to the Federal Emergency Management Agency and 

its state counterparts.

PML Zone and Modified Mercalli Intensities

Although damage extended throughout many counties 

around the San Francisco Bay, including those to the south 

around Monterey Bay (fig. 1), the heaviest shaken area 

was in the lightly inhabited regions within the Santa Cruz 

Mountains (fig. 3). This heaviest shaken area within 6 

miles of the earthquake's energy release is defined as the 

PML zone shown in figure 3. The PML zone reasonably 

coincided with Modified Mercalli intensity VIE (fig. 14).

Average percentage losses within the MM VIE isoseismal boundary can be estimated by losses within the 

PML zone (see below under "Deductibles)." Other studied 

earthquakes have had significantly different percent losses 

for this same intensity. In general, comparisons among 

earthquakes show poor correlations between intensities 

and actual losses.

Many regions within the United States do not have 

earthquake insurance loss data available. They may be 

many decades away from obtaining such information. 

Transferability of California loss experience to different 

geologic environments may involve great uncertainties. 

The use of intensities in dwelling loss estimation is useful 

only when suitable loss data are not available.

Dwelling Age and Loss

Dwellings constructed prior to 1940 suffered much 

more damage than did subsequent construction. This has 

also been observed in all California earthquakes since 

1971. There was insufficient Loma Prieta data on older 

homes to adequately quantify comparisons. The most recent quantified comparison was the 1983 Coalinga earthquake which showed that the pre-1940 wood frame 

dwellings had twice the percentage loss as did the more 

recent construction. There is some reason to believe that 

the Coalinga experience is not entirely applicable to the

Dwelling and Mobile Home Monetary Losses Due to the 1989 Loma Prieta, California, Earthquake, with an Emphasis on Loss Estimation B57
more seismic areas of California. The ratio between old 

and new is expected to be greater than two for non-retrofitted older houses.

Pre-1940 dwellings constituted only 8.8 percent of the 

fire insured dwellings in the study area, and this percentage 

has been constantly decreasing (table 7). A few of the pre1940 dwellings have since been earthquake retrofitted and 

this practice is continuing. Demolition for other land-use 

purposes is also reducing the number. While many individual older dwellings will have large losses, the aggregate 

loss for all dwellings including those of all ages will not be 

greatly increased.

It is usually practical for aggregate loss estimation 

purposes to disregard dwelling age. The losses to older 

communities and/or cities within a large damage area can 

be exceptions. San Francisco, having a large number of 

older houses and with its relatively uncommon type of two 

story dwellings, will be prone to heavier than average 

damage. It will also be more vulnerable to ensuing fire. 

See table 3 and section "Source B Data".

Retrofitting is strongly recommended. This may not 

always be cost effective from a purely financial standpoint 

(including insurance), but personal safety and peace of 

mind are valid and strong homeowner concerns.

Geohazards

Geohazard sites are defined as those in geologic hazard areas having a landslide potential and those with unstable ground such as liquefiable soils. Also included are 

dwellings on steeply sloping sites where construction characteristics create hazards on otherwise stable sites. This 

definition also applies to postearthquake losses. Dwelling 

losses due to geohazards amounted to about 27 percent of 

the total losses in the study area (see section "Elimination 

of Major Geohazard Losses"). This high percentage must 

be understood in the context of the epicenter and number 

of dwellings in the Santa Cruz Mountains.

Deductibles

Source data on losses invariably included a deductible 

which varied in amount and sometimes in restrictions on 

its application. The process in developing generalized loss 

over deductible equations from Loma Prieta and those 

from other earthquakes are discussed. Equation 7 is the 

generalized result which includes magnitude and a userselectable uncertainty factor and is intended for computer 

use. It is applicable to large groups of dwellings such as 

those found in a postal ZIP.

After earthquake losses have been compiled, geohazard losses can be eliminated. The loss algorithm is then 

usable for postulated earthquakes elsewhere having the 

same magnitude and geologic environments. Geohazards 

in the new study area are then included.

When excluding geohazard sites, examples of average 

dwelling loss to post-1939 construction in the PML zone 

with zero deductible are for a repeat of:

Loma Prieta earthquake: 

Loma Prieta earthquake: 

1906 San Francisco:

6.5 percent, equation 1, 

Watsonville data 

5.8 percent, equation 7, 

form for general use 

8.7 percent, equation 7, 

form for general use

Table 15 may be used instead of equation 7. Local geohazards must be included in the loss estimation algorithm. 

The discussion on the limitations and uncertainties surrounding these percentages should be heeded.

Loss Attenuation With Distance

Losses reduce rapidly with distance. In the Loma Prieta earthquake, the average percent loss becomes low at 

10 miles from the fault (fig. 6). At distances beyond 10 

miles, losses became very small except at geohazard sites 

(figs. 12 and 13). The 1992 Landers earthquake provided 

information on losses up to 3 percent of value at distances 

as far as 40 miles (see section "1992 Landers Earthquake"). Bear in mind that deductibles apply, with those 

for Landers being much less that the other two.

Losses up to 5 percent of value have not been well 

studied due to the sparsity of reliable data. Indications are 

that the aggregate losses would be very large if damage 

was not repaired and paid for by the homeowner.

Contents Losses

When dwellings were not destroyed, losses to their 

contents were about 20 to 25 percent of the building loss 

(table 16). For aggregate loss estimating purposes, the average percent dwelling loss can be increased by 25 percent, 

admitting wide variations in valuations and susceptibilities 

among building and contents.

Ensuing Fire

While the news media immediately showed fires burning in San Francisco, the losses attributed directly to fire 

were only 7.5 percent of the homeowner losses in the study 

area. This percentage is expected to be higher for an earthquake of similar magnitude located within a highly populated area under weather conditions such as those at the 

time of the Loma Prieta earthquake. Adding adverse climatic conditions such as strong, dry, and hot winds, then 

widespread conflagrations are possible in a number of 

major residential areas. Experience from recent winddriven conflagrations without earthquake in the San Francisco Bay area and in metropolitan Los Angeles with its 

Santa Ana winds are examples of the problems. The fire

B58 Estimation of Earthquake Losses to Housing in California
departments were almost overwhelmed from these conflagrations. With their added responsibilities after a great 

earthquake such as a repeat of 1906 San Francisco, the 

totality of the disaster is difficult to estimate. Fortunately, 

the simultaneous occurrence of a great earthquake and 

these severe climatic conditions has a very low probability.

Research Needs

The fundamental needs for improved predictive loss 

estimation require an improved integration of three major 

components:

(1) Actual loss statistics in place of the subjective 

Modified Mercalli intensities.

(2) Strong motion records for attenuation characteristics which correlate with losses.

(3) Site or area quantification of geohazards which 

correlates with both of the above.

Subsequent algorithms should include other measurable 

quantities and clearly identified criteria which include 

magnitude, type of faulting, focal depth, characteristics of 

the energy release volume, and regional geology. Some 

work on this already exists and progress would likely be 

incremental over many years.

Nondwelling construction types are normally more 

complicated since the dynamic characteristics and the design/construction qualities are added variables.

Mobile Homes (Manufactured Housing)

Nonbraced Mobile Homes

Mobile homes which lack earthquake bracing are 

very vulnerable to falling off their supports. Within 20 

miles of the Loma Prieta earthquake, about 25 percent of 

the approximately 2,500 mobile homes fell from their supports (table 31). Similar experience occurred in the 1971 

San Fernando, 1978 Santa Barbara, 1979 El Centra, 1980 

Livermore, and 1983 Coalinga earthquakes.

The percent of fallen mobile homes in nearby parks 

may vary by large margins. In the city of Watsonville which 

is in the PML zone, the percent of fallen coaches ranged 

from 5 to 64 percent, with the upper limit probably influenced by a steep nearby slope (table 31 and fig. 7). However, 

the percent loss for the upper limit was only 17 percent. The 

reason is that once fallen, little additional damage is the 

general rule. This effectively put the maximum loss considerably under the total loss for a fallen coach.

Earthquake Bracing

Commercially available earthquake bracing performed 

excellently. None of the 46 known mobile homes with

bracing fell from their supports (table 31). More limited 

experience in other earthquakes showed similar excellent 

results. While perfect performance is not to be expected in 

the future, there is certainly no doubt of the effectiveness 

of earthquake bracing.

Retrofitting mobile homes is quite simple, inexpensive, and cost effective. It would seem reasonable public 

policy to require retrofitting or new bracing whenever 

ownership changes, a new mobile home is acquired, or 

one is moved to a new site.

Loss Attenuation

Excluding geohazards, percent losses for mobile 

homes per park were under 10 percent at 20 miles (fig. 

16). This compares with 10 miles for wood frame dwellings (fig. 5). A different loss attenuation algorithm is required for each.

Research Needs

The research needs for mobile homes are similar to 

those for wood frame dwellings but are not as needy or 

expensive. Emphasis should be placed on implementing 

retrofitting before spending time and resources on nonbraced mobile homes.

Comparative Losses: Wood Frame and Mobile Homes

The 9.8 percent loss for Loma Prieta mobile homes is 

about twice the 5.3 percent for wood frame dwellings 

(equations 9 and 5, respectively). For 1971 San Fernando, 

table 34 shows that mobile homes were from 2 to 4 times 

more vulnerable to loss than were wood frame dwellings. 

This observation is limited to nonearthquake braced mobile homes.

REFERENCES

Applied Technology Council, 1989, Field manual: postearthquake safety evaluation of buildings: Redwood City, California, ATC-20-1, p. 114.

Barrows, A.G., Kahle, J.E., Weber, Jr., F.H., and Saul, R.B., 1973, 

Map of surface breaks resulting from the San Fernando, California, earthquake of February 9, 1971", in San Fernando, 

California, earthquake of February 9, 1971: NOAA, U.S. Department of Commerce, v. 3, p. 127-135, plus map in pocket.

Benuska, L., ed., 1990, Loma Prieta earthquake reconnaissance 

report, in supplement to v. 6: Earthquake Spectra, May 1990.

Bonilla, M.G., Lienkaemper, J.J., and Tinsley, J.C., 1980, Surface 

faulting near Livermore, California, associated with the January, 1980, earthquake: U.S. Geological Survey Open-File 

Report 80-523.

California Department of Housing and Community Development, 

1989(7), Evaluation of manufactured housing support system

Dwelling and Mobile Home Monetary Losses Due to the 1989 Loma Prieta, California, Earthquake, with an Emphasis on Loss Estimation B59
performance in the Loma Prieta earthquake: Sacramento, 

California, 14 p.

California Department of Insurance, 1981 [and annually thereafter], California earthquake zoning and probable maximum 

loss program: 54 p.

Cloud, W.K., and Perez, V., 1967, Accelerograms Parkfield earthquake: Seismological Society Bulletin, v. 57, p. 1179-1192.

Earthquake Engineering Research Institute, Newsletter, September, 1992: p. 6.

Housner, G.W., and Trifunac, M.D., 1967, Analysis of accelerograms Parkfield Earthquake: Seismological Society Bulletin, v. 57, p. 1193-1220.

Kensler, C.D., 1985, The Morgan Hill earthquake of April 24, 

1984 effects on mobile homes: Earthquake Spectra, v. 1, 

p. 607-613.

Lawrence Livermore Laboratory, 1980, The LLNL earthquake 

impact analysis committee report on the Livermore, California, earthquakes of January 24 and 26, 1980: Lawrence Livermore Laboratory, Univ. of Calif., Livermore, California, 

107 p.

Lawson, A.C., ed., 1908, The California earthquake of 1906, report of the State Earthquake Investigation Commission: Carnegie Institution of Washington, 2 volumes plus atlas, 

Washington, D.C.

McNutt, S.R., and Toppozada, T.R., 1990, Seismological aspects 

of the 17 October 1989 earthquake, in The Loma Prieta 

(Santa Cruz Mountains), California earthquake of October 

17, 1989: California Division of Mines and Geology, Special 

Publication 104, Sacramento, California.

Plafker, G., and Gallaway, J.P., eds., 1989, Lessons learned from 

the Loma Prieta, California, earthquake of October 17, 1989: 

U.S. Geological Survey Circular 1045, 48 p.

Steinbrugge, K.V., 1970, Engineering aspects of the Santa Rosa, 

California, earthquakes, October 1, 1969, in The Santa Rosa 

earthquakes of October 1, 1969: U.S. Coast and Geodetic 

Survey, ESSA, Dept. of Commerce, Washington, D.C.

Steinbrugge, K.V., 1986, Comment on the use and misuses of 

Modified Mercalli intensities, in Proceedings of Conference 

XXXII, Workshop on Future Directions in Evaluating Earthquake Hazards of Southern California: U.S. Geological Survey Open-File Report 86-401.

Steinbrugge, K.V., 1990, Earthquake losses to 1- to 4-family California dwellings: who pays?, in Hearings before the Subcommittee on Policy Research and Insurance Committee on

Banking, Finance and Urban Affairs: House of Representatives, Sept. 11 and 12, 1990, Serial No. 101-168, p. 798-808.

Steinbrugge, K.V., and Algermissen, S.T., 1990, Earthquake losses to single-family dwellings: California experience: U.S. 

Geological Survey Bulletin 1939.

Steinbrugge, K.V., Algermissen, S.T., and Lagorio, H.J., 1984, 

Determining monetary losses and casualties for use in earthquake mitigation and disaster response planning, in Proceedings, 8th World Conference on Earthquake Engineering, San 

Francisco, California, July 21-28, 1984: Prentice-Hall, v. VII, 

p. 615-622.

Steinbrugge, K.V., Bush, V.R., and Zacher, E.G., 1959, Damage 

to buildings and other structures by the San Francisco earthquake of March 22, 1957, in Oakeshott, Gordon B., ed., San 

Francisco earthquakes of March 1957: California Division of 

Mines, Special Report 57.

Steinbrugge, K.V., Fowkes, E.J., Lagorio, H.J., and Algermissen, 

S.T., 1990, Dwelling monetary losses, in The Coalinga, California, earthquake of May 2, 1983: U.S. Geological Survey 

Professional Paper 1487.

Steinbrugge, K.V., Manning, J.H., and Degenkolb, H.J., 1967, 

Building damage in Anchorage, in The Prince William 

Sound, Alaska, earthquake of 1964 and aftershocks: ESSA, 

U.S. Department of Commerce, v. II, part A, p. 7-217, plus 

map in pocket.

Steinbrugge, K.V., and Schader, E.E., 1979, Mobile home damage and losses, Santa Barbara earthquake, August 13, 1978: 

California Seismic Safety Commission, Sacramento, California, SSC 79-06, 19 p.

Steinbrugge, K.V., Schader, E.E., and Algermissen, ST., 1980, 

Mobile homes and earthquake damage in California: California Seismic Safety Commission, Sacramento, California, 

SSC 79-07, 29 p.

Steinbrugge, K.V., Schader, E.E., Bigglestone, H.C., and Weers, 

C.A., (n.d., but 1971), San Fernando earthquake, February 9, 

1971: Pacific Fire Rating Bureau, San Francisco, California, 

93 p., plus map in pocket.

Stover, C.W, and others, 1990, Preliminary isoseismal map for 

the Santa Cruz (Loma Prieta), California, earthquake of October 18, 1989, UTC: U.S. Geological Survey Open-File Report 90-18.

Youd, T.L., and Perkins, J.B., 1987, Map showing liquefaction 

susceptibility of San Mateo County, California: U.S. Geological Survey Miscellaneous Investigation Series, Map I-1257-G.

B60 Estimation of Earthquake Losses to Housing in California
APPENDIX A. SENSITIVITY: LOSS OVER 

DEDUCTIBLE VERSUS DWELLING PML 

CHANGES

The term "percent PML" is frequently misunderstood. 

For convenience, discussion found in Steinbrugge and Algermissen (1990, p. A65) has been updated and reproduced here.

The commercial/industrial underwriters emphasize individual risks in their aggregate loss evaluations, whereas 

personal lines underwriters emphasize large numbers of 

risks. Commonly stated, the percent PML minus the percent deductible is the percent loss over the deductible. In a 

mathematical sense:

(percent PML) - (percent deductible) = 

(percent loss over the deductible)

These terms may be rearranged:

(percent PML) = 

(percent loss over the deductible) + (percent deductible)

This latter form is used in the following discussion. The 

percent PML for wood frame dwellings is not a fixed 

value since it is always in the context of a deductible plus 

the loss over the deductible. For example, consider a damaging earthquake during which 1,000 wood frame dwellings in a small area are subjected to the same severe 

ground motion. First, assume that two dwellings are total 

losses and the others have losses distributed between 0 

percent and 100 percent. With a 10 percent deductible and 

using the current State of California's 1.7 percent loss over 

this deductible, the result is an 11.7 percent PML. Next 

assume a highly improbable deductible of 95 percent. 

There still would be at least two dwelling losses over the 

95 percent deductible. The percent PML for the 1,000 

houses would therefore have to be the 95 percent deductible plus a very small loss over the deductible to reflect 

the two total losses plus any other losses between 95 percent and 100 percent. In summary, the percent PML varies 

as a function of the percent deductible and may never be 

less than the percent deductible.

If the percent PML is close to the percent deductible 

as in the case for wood frame dwellings, the percent loss 

over the deductible is very sensitive to any change in the 

percent PML. Consider a 10 percent deductible with an 

11.7 percent PML for wood frame dwellings. For $1 billion in wood frame dwelling liabilities, the loss over the 

deductible would be 1.7 percent of $1 billion, or $17 million. On the other hand should the maximum credible 

earthquake actually produce a 12.7 percent PML instead 

of 11.5 percent, then the loss over the deductible would be 

2.5 percent, or $25 million. In this case, a 1 percent increase in the percent PML creates a 47 percent increase in 

the aggregate dollar PML.

APPENDIX B. DEFINITIONS OF DEGREE OF 

DAMAGE TO MOBILE HOMES

The following definitions of degree of damage require 

a physical inspection of each coach consisting of an examination of not less than the front and two sides. Except 

occasionally, interiors are not inspected. Minor exterior 

damage such as disturbed caulking and slightly bent skirting may escape observation from these rapid inspections.

Contents damage is usually not evaluated during 

these inspections. However, such information may be 

eventually obtained when the degree of coach damage is 

correlated with the closed insurance claims.

NONE is defined as a coach which has no visible exterior damage upon a quick three-sided inspection of the 

unit. Often minor damage can be found during a detailed 

inspection which includes crawling under the unit.

SLIGHT damage is defined as a coach which has 

skirting damage principally on one side, indicating that 

relative minor movement took place. Skirting is normally 

metal although masonry or fiberboard are sometimes observed. Replacement of the damaged portion of the skirting, slight releveling, and recaulking of roof seams at the 

joint line are the anticipated repairs.

MODERATE damage is defined as a coach which has 

skirting damage on several sides, and possibly on all sides. 

Releveling and caulking problems are significantly greater 

than for "slight" damage. Minor permanent offsets of the 

coach and porch may be observed upon careful inspection.

SEVERE damage is defined as a coach which is totally or partially off its supports. Alternatively, the coach 

may have substantially shifted with respect to its supports 

which may be bent or rotated. Skirting is severely damaged. Awnings and porches are damaged, with displacements commonly observed between coaches and porches. 

Unobserved damage may include holes punched through 

the floor when the coach leaves its supports. We now believe that SEVERE should be divided into two categories: 

(1) partly off supports and (2) completely off supports.

The technique used in the past to apply these guidelines 

has been:

(1) For all parks within a reasonable distance from 

the earthquake, field inspect all coaches in each 

park using a damage classification system such 

as that found in Appendix B. If practical, a more 

sophisticated system should be used. From a 

time standpoint the surveys probably should be 

restricted to external inspections with interiors 

examined only when convenient.

(2) Determine from the mobile home park manager, 

or others, an estimate of the average value of 

each coach in the park on some consistent basis, 

such as the replacement value or current resale

Dwelling and Mobile Home Monetary Losses Due to the 1989 Loma Prieta, California, Earthquake, with an Emphasis on Loss Estimation B61
value. Preferably, the valuations should be on a classification system described in Appendix B is

single-wide, double-wide, and so forth basis. used.

This should be eventually related to insured val- Refinements to this system can include type of foundation

ues and to paid claims in order to improve the such as steel or concrete piers, wood blocks, or hollow

methodology. concrete blocks. Data tabulation can include information

(3) Compute the loss using loss percentages such as on the bracing, if any, be it state certified or not. This latthose found in previous sections if the damage ter refinement is the more important of the two.

B62 Estimation of Earthquake Losses to Housing in California
Table 44. Building, contents, and Ale losses, before and after deductible. 

[See text under "Dwelling Losses Before and After Deductible" for explanation]

DATA FILE STATE-6A.DAT DISTRIBUTION OF BUILDING AND CONTENTS LOSSES BY ZIP DATA IN ZIP-FAULT ORDER (Column 2) 

ALAMEDA, CONTRA COSTA, MARIN. MONTEREY, SAN BENITO. SAN FRANCISCO, SAN MATED. SANTA CLARA, and SANTA CRUZ Counties

ZIP 

FAULT 

ZIP DIST.

(1)

95019

95076

95026

95044

95001

95003

95066

95073

95007

95006

95005

95065

95018

95030

95010

95041

95031

95061

95062

95032

95004

95070

95064

95060

95020

95141

93907

95120

95124

95130

(2)

2.0

2.1

2.7

2.7

3.5

3.5

3.9

4.3

4.6

4.7

4.8

5.3

5.5

5.7

5.9

5.9

6.5

7.5

7.5

7.6

8.3

8.5

8.6

8.9

9.6

9.6

10.0

10.0

10.0

10.0

<=mmu i,uytK"»=> « 

DWEL. CONTS. 

NO. VALUE VALUE 

DWEL. x$MTl. x$Mil.

(3)

14

422

1

5

1

475

294

165

11

216

159

129

156

883

62

13

1

1

273

576

42

1.372

2

504

489

1

186

1.798

1,096

322

(4)

1

58

0

0

0

76

47

26

1

29

21

20

19

188

8

2

0

0

33

114

5

313

0

76

72

0

24

321

149

39

(5)

1

42

0

0

0

57

35

19

1

21

15

15

13

141

6

1

0

0

24

87

4

237

0

56

54

0

18

243

112

30

:= PAID LOSS UNDER EQ COVER ==> <= PAID LOSS UNDER HO COVER => < 

NO. PCT. DWEL. CONTS. ALE NO. PCT. DWEL. CONTS. ALE NO. 

DWEL. DWEL. x$1000 x$1000 x$1000 DWEL. DWEL. x$1000 x$1000 xJlOOO DWEL

(6)

3

150

1

3

1

201

115

81

2

92

62

59

66

348

16

0

0

0

72

70

5

85

0

132

45

0

11

52

20

6

(7)

21.4

35.5

100.0

60.0

100.0

42.3

39.1

49.1

18.2

42.6

39.0

45.7

42.3

39.4

25.8

0.0

0.0

0.0

26.4

12.2

11.9

6.2

0.0

26.2

9.2

0.0

5.9

2.9

1.8

1.9

(8)

27

3,884

39

85

71

3,849

2,246

2,702

60

2,542

1,049

1.351

1.224

16.300

143

0

0

0

1.191

1,515

33

1.756

0

2.708

768

0

136

745

178

9

(9)

9

1,044

0

44

19

885

540

579

2

411

194

434

213

4,574

38

0

0

0

343

608

30

312

0

291

230

0

14

217

75

9

(10) (11)

0

278

17

2

30

211

156

370

5

203

44

131

114

2.058

9

0

0

0

57

79

2

149

0

161

51

0

6

32

3

0

1

16

0

1

1

19

9

9

0

14

4

3

5

80

2

0

0

0

2

6

0

5

0

11

0

0

2

1

0

0

(12)

7.1

3.8

0.0

20.0

100.0

4.0

3.1

5.5

0.0

6.5

2.5

2.3

3.2

9.1

3.2

0.0

0.0

0.0

0.7

1.0

0.0

0.4

0.0

2.2

0.0

0.0

1.1

0.1

0.0

0.0

(13)

1

157

0

0

13

126

133

77

0

142

13

7

33

1.328

5

0

0

0

18

40

0

44

0

54

0

0

2

0

0

0

(14)

0

3

0

2

0

19

76

28

0

10

2

11

0

274

0

0

0

0

0

3

0

0

0

1

0

0

0

0

0

0

(15)

0

1

0

0

0

45

30

2

0

2

0

0

0

36

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

 EQ COVER > < HO COVER > < EO+HO CO

NO. NO. 

. BLDG. CONTS. ALE DWEL. BLDG. CONTS. ALE DWEL. BLDG. CO

(16) (17)

3

150

1

3

1

201

115

81

2

92

62

59

66

348

16

0

0

0

72

70

5

85

0

132

45

0

11

52

20

6

57

6,698

55

101

216

6.592

3,995

4,557

80

3,963

1,817

2.467

2,017

27.274

317

0

0

0

2,086

3,087

85

3,461

0

4.431

1.353

0

255

1,419

437

72

(18) (19) (20)

9

1.044

0

44

19

885

540

579

2

411

194

434

213

4,574 2

38

0

0

0

343

608

30

312

0

291

230

0

14

217

75

9

0

278

17

2

30

211

156

370

5

203

44

131

114

,058

9

0

0

0

57

79

2

149

0

161

51

0

6

32

3

0

1

16

0

0

1

15

8

9

0

14

2

2

5

76

2

0

0

0

2

6

0

5

0

10

0

0

2

1

0

0

(21)

1

157

0

0

13

126

133

77

0

142

13

7

33

877

5

0

0

0

18

40

0

44

0

54

0

0

2

0

0

0

(22)

0

3

0

2

0

19

76

28

0

10

2

11

0

274

0

0

0

0

0

3

0

0

0

1

0

0

0

0

0

0

(23) (24) (25)

0

1

0

0

0

45

30

2

0

2

0

0

0

36

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

3

150

1

3

1

201

115

81

2

92

62

59

66

348

16

0

0

0

72

70

5

85

0

132

45

0

11

52

20

6

59

6.854

55

101

229

6.718

4.128

4.634

80

4.104

1,829

2.474

2.050

28,151

322

0

0

0

2.104

3.127

85

3,506

0

4.485

1.353

0

257

1,419

437

72

(

1.

4.
Table 44. Buildine, contents, and Ale losses, before and after deductible Continued

DATA FILE STATE-6A.DAT DISTRIBUTION OF BUILDING AND CONTENTS LOSSES BY ZIP DATA IN ZIP-FAULT ORDER (Column 2) 

ALAMEDA, CONTRA COSTA, MARIN, MONTEREY, SAN BENITO, SAN FRANCISCO, SAN MATED. SANTA CLARA, and SANTA CRUZ Counties

ion ofEarthi

jz

5"

5-

It/1 8"

o

era5*

nw

1

5*

ZIP 

FAULT

ZIP DIST.

(1) (2)

95008 10.2

95012 10.4 

95129 10.8

95039 10.9

95118 11.1

95014 11.3

95017 11.5 

95117 11.8

95123 12.6

95128 12.7

95037 12.9

95046 13.0

95125 13.0

95136 13.1

95119 13.2

94087 13.5

94024 13.7

95051 13.8

95126 13.8

95139 13.9

95050 14.3

95052 14.3

95114 14.4

95150 14.4

95157 14.4

95160 14.4

95045 14.5

94088 14.7

95111 14.8

94022 14.9

<=EQ+HO COVE 

DWEL. 

NO. VALUE

CONTS. < 

VALUE

DWEL. x$Mil. x$Mil.

(3)

572

23 

1,033

1

626

1.482

3 

295

1,284

366

745

78

757

687

290

1,297

96

966

135

207

364

1

2

10

1

1

29

1

347

1.835

(4)

75

2 

141

0

79

236

0 

40

168

46

138

15

108

95

39

189

20

119

20

28

43

0

0

1

0

0

4

0

41

432

(5)

57

2

106

0

59

178

0 

30

126

34

103

11

80

71

29

143

15

89

14

21

32

0

0

1

0

0

3

0

30

327

 PAID LOS 

NO. PCT.

DWEL.

(6)

13

1 

31

0

7

77

0 

12

35

5

41

8

50

20

9

9

6

34

4

2

6

0

0

0

0

0

1

0

4

127

DWEL.

(7)

2.3

4.3 

3.0

0.0

1.1

5.2

0.0 

4.1

2.7

1.4

5.5

10.3

6.6

2.9

3.1

0.7

6.3

3.5

3.0

1.0

1.6

0.0

0.0

0.0

0.0

0.0

3.4

0.0

1.2

6.9

= AGGREGATE LOS! 

iS UNDER EQ COVEI 

DWEL. CONTS.

x$1000

(8)

126

8 

182

0

23

718

0 

176

369

113

1.059

61

1,073

452

77

76

336

335

31

1

69

0

0

0

0

0

48

0

25

4,623

5ES AFTER DEDUCTIBLE 

R => <= PAID LOS 

ALE NO. PCT.

x$1000 x$1000

(9)

23

0 

88

0

4

303

0 

21

70

22

140

44

52

9

31

74

17

51

2

3

18

0

0

0

0

0

21

0

8

1,611

(10)

36

2 

2

0

0

19

0 

4

16

0

57

0

47

29

1

0

0

7

0

0

3

0

0

0

0

0

31

0

1

456

DWEL.

(11)

0

0 

4

0

0

1

0 

0

1

0

1

1

2

0

0

0

1

0

0

0

0

0

0

0

0

0

1

0

0

22

DWEL.

(12)

0.0

0.0 

0.4

0.0

0.0

0.1

0.0 

0.0

0.1

0.0

0.1

1.3

0.3

0.0

0.0

0.0

1.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

3.4

0.0

0.0

1.2

iS UNDER 

DWEL.

x$1000

(13)

0

0 

14

0

0

1

0 

0

0

0

8

1

5

0

0

0

2

0

0

0

0

0

0

0

0

0

4

0

0

125

HO COVER > 

CONTS. ALE

<=sa=s=

NO.

x$1000 x$1000 DWEL.

(14)

0

0 

0

0

0

0

0 

0

0

0

1

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

4

(15)

0

0 

0

0

0

0

0 

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

(16)

13

1 

31

0

7

77

0 

12

35

5

41

8

50

20

9

9

6

34

4

2

6

0

0

0

0

0

1

0

4

127

= EQ COVER =

BLDG.

(17)

318

18 

552

0

111

1,721

0 

325

760

328

1,848

172

1,837

759

179

181

644

710

89

23

146

0

0

0

0

0

100

0

70

8,413

CONTS.

(18)

23

0 

88

0

4

303

0 

21

70

22

140

44

52

9

31

74

17

51

2

3

18

0

0

0

0

0

21

0

8

1,611

REGATE LOSSES BEFORE DEDUCTIBLE x $11

====> <-, . HO COVER MM.. ,...!..,> <=

NO. NO.

ALE

(19)

36

2 

2

0

0

19

0 

4

16

0

57

0

47

29

1

0

0

7

0

0

3

0

0

0

0

0

31

0

1

456

DWEL.

(20)

0

0 

4

0

0

1

0 

0

1

0

1

1

2

0

0

0

1

0

0

0

0

0

0

0

0

0

1

0

0

22

BLDG.

(21)

0

0 

14

0

0

1

0 

0

0

0

8

1

5

0

0

0

2

0

0

0

0

0

0

0

0

0

4

0

0

125

CONTS.

(22)

0

0 

0

0

0

0

0 

0

0

0

1

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

4

ALE

(23)

0

0 

0

0

0

0

0 

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

DWEL.

(24)

13

1 

31

0

7

77

0 

12

35

5

41

8

50

20

9

9

6

34

4

2

6

0

0

0

0

0

1

0

4

127

= EO+HO CO

BLDG.

(25)

318

18 

566

0

111

1,721

0 

325

761

328

1.856

173

1.842

759

179

181

646

710

89

23

146

0

0

0

0

0

104

0

70

8,538

CO

1
Table 44. Building, contents, and Ale losses, before and after deductible Continued

DATA FILE STATE-6A.DAT DISTRIBUTION OF BUILDING AND CONTENTS LOSSES BY ZIP DATA IN ZIP-FAULT ORDER (Column 2) 

ALAMEDA, CONTRA COSTA, MARIN, MONTEREY, SAN BENITO. SAN FRANCISCO, SAN MATED, SANTA CLARA, and SANTA CRUZ C6unties

bile Home Monetary Lo

1</j

a

n

$

?

irOi

7

f

n

SL

f

F

m

.g

f.

?

{»

3

m

3

I5*

§

ri

E

g.

§

09

ZIP 

FAULT 

ZIP DIST. 

(1) (2)

93906 15.0

95110 15.0

94021 15.2

95138 15.2

94086 15.3

94040 16.0

95112 16.0

94041 16.1

93912 16.3

93915 16.3

95121 16.5

93933 16.9

94060 16.9

95122 17.0

94089 17.2

95054 17.3

93905 17.4

95116 17.5

94043 17.6

93901 17.8

94020 18.2

95023 18.5

95133 18.5

94306 18.6

95131 18.7

95135 18.7

95148 18.9

95002 19.2

95127 19.4

94304 19.6

DWEL. CONTS. <= PAID LOSS UNDER EQ COVER > <= PAID LOSS UNDER HO COVER => < 

NO. VALUE VALUE NO. PCT. DWEL. CONTS. ALE NO. PCT. DWEL. CONTS. ALE NO. 

DWEL. x$Mi1. x$Mi1. DWEL. DWEL. x$1000 x$1000 x$1000 DWEL. DWEL. x$1000 x$1000 x$1000 DWEL. 

(3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (16)

246 24 17 2 0.8 5 0 1 1 0.4 0 002

27

5

100

523

515

108

91

1

1

397

102

10

210

82

111

83

100

176

218

39

306

324

659

293

195

681

1

629

21

3

1

13

68

83

13

14

0

0

49

11

2

22

9

13

7

10

22

28

7

41

45

99

38

30

95

0

86

8

2

1

10

51

62

9

11

0

0

36

8

1

16

6

10

5

7

16

20

5

30

34

74

28

23

70

0

63

6

0

0

0

4

4

1

0

0

0

2

0

0

2

1

1

0

1

3

2

4

14

2

9

2

5

14

0

13

0

0.0

0.0

0.0

0.8

0.8

0.9

0.0

0.0

0.0

0.5

0.0

0.0

1.0

1.2

0.9

0.0

1.0

1.7

0.9

10.3

4.6

0.6

1.4

0.7

2.6

2.1

0.0

2.1

0.0

0

0

0

18

42

1

0

0

0

17

0

0

3

4

3

0

1

23

8

136

184

44

237

8

21

73

0

343

0

0

0

0

4

25

0

0

0

0

0

0

0

0

0

0

0

0

0

0

3

24

3

9

0

2

6

0

10

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

,0

1

4

5

2

42

1

0

2

0

19

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

1

0

0

0

0

2

0

0

0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.3

0.0

0.0

0.0

0.0

0.3

0.0

0.0

0.0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

1

0

0

0

0

3

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

4

4

1

0

0

0

2

0

0

2

1

1

0

1

3

2

4

14

2

9

2

5

14

0

13

0

- EQ COVER ===> <= = HO COVER > < EO+HO COV

NO. NO. 

BLDG. CONTS. ALE DWEL. BLDG. CONTS. ALE DWEL. BLDG. CON

(17) (18) (19) (20) (21) (22) (23) (24) (25) (

26 Oil 0 002 26 

0

0

0

58

92

11

0

0

0

46

0

0

24

14

13

0

11

54

30

233

434

64

387

31

81

254

0

597

0

0

0

0

4

25

0

0

0

0

0

0

0

0

0

0

0

0

0

0

3

24

3

9

0

2

6

0

10

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

1

4

5

2

42

1

0

2

0

19

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

1

0

0

0

0

2

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

1

0

0

0

0

3

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

4

4

1

0

0

0

2

0

0

2

1

1

0

1

3

2

4

14

2

9

2

5

14

0

13

0

0

0

0

58

92

11

0

0

0

46

0

0

24

14

13

0

11

54

30

233

435

64

387

31

81

257

0

597

0
B66 Estimation ofEarthquake Lo

18"

z

§

5*

era

5*

S

r

S'

Table 44. Building

DATA FILE STATE-6A.DAT 

ALAMEDA. CONTRA COSTA, MARI

<=EQ+HO COVER 

ZIP DWEL. C 

FAULT NO. VALUE V 

ZIP DIST. DWEL. x$Mil. x$ 

(1) (2) (3) (4)

94305 19.6

94309 20.1

95075 20.2

95132 20.2

94301 20.7

94303 21.0

94025 21.3

95035 21.3

93908 21.8

95140 22.5

93955 22.8

94061 23.6

94062 23.9

94064 24.0

94063 24.2

93950 24.3

93940 24.8

94538 26.2

94539 26.3

93953 26.4

94070 26.4

94560 26.5

94065 27.7

93921 27.8

93922 27.9

94536 28.1

93923 28.3

94002 28.4

94555 29.0

93925 29.3

95

1

5

990

280

660

1,341

912

113

7

137

544

730

1

117

161

263

762

1.636

116

826

683

191

70

6

1.192

221

708

628

5

21

0

0

132

62

100

305

127

20

2

14

85

163

0

14

20

45

88

280

29

146

83

32

12

1

159

52

122

85

1

;, com

DISTR:

N. MONTI

ONTS. <= 

ALUE 

Mil. I 

(5)

16

0

0

98

47

74

230

93

15

2

10

62

120

0

10

15

33

65

210

22

110

61

24

9

1

118

38

91

64

1

tents, and

IBUTION OF BU 

EREY. SAN BEN

 PAID LOSS 

NO. PCT. 

)WEL. DWEL. x 

(6) (7)

3

0

0

10

2

4

21

6

1

0

0

3

19

0

0

0

2

3

10

1

3

0

0

2

0

1

1

7

0

0

3.2

0.0

0.0

1.0

0.7

0.6

1.6

0.7

0.9

0.0

0.0

0.6

2.6

0.0

0.0

0.0

0.8

0.4

0.6

0.9

0.4

0.0

0.0

2.9

0.0

0.1

0.5

1.0

0.0

0.0

1 Ale losses, before and afte

IILDING AND CONTENTS LOSSES BY ZIP 

IITO. SAN FRANCISCO. SAN MATED, SANTA

 AGGREGATE LOSSES AFTER DEDUCTIBLE x$ 

, UNDER EQ COVER => <s PAID LOSS 

DWEL. CONTS. ALE NO. PCT. D 

$1000 x$1000 xJlOOO DWEL. DWEL. x$ 

(8) (9) (10) (11) (12) (

84 -

0

0

303

37

14

579

26

6

0

0

28

230

0

0

0

18

12

44

2

12

0

0

7

0

1

6

50

0

0

5

0

0

5

0

39

35

1

0

0

0

4

125

0

0

0

12

0

4

0

0

0

0

0

0

0

0

0

0

0

11

0

0

22

0

2

0

1

0

0

0

0

21

0

0

0

5

0

0

0

0

0

0

0

0

0

1

0

0

0

2

0

0

0

0

0

0

0

0

0

0

0

1

0

0

0

0

0

0

0

0

0

0

0

0

0

0

1

0

0

2.1

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.1

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.1

0.0

0.0

ir deductible Continued

DATA IN ZIP-FAULT ORDER (Column 

CLARA, and SANTA CRUZ Counties

UNDER HO COVER =-> 

IWEL. CONTS. ALE 

1000 xUOOO x$1000 

13) (14) (15)

4

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

< = 

NO. 

DWEL. 

(16)

3

0

0

10

2

4

21

6

1

0

0

3

19

0

0

0

2

3

10

1

3

0

0

2

0

1

1

7

0

0

 EQ C0\

BLDG. 1 

(17)

162

0

0

496

57

55

1.326

86

16

0

0

59

676

0

0

0

54

43

185

12

52

0

0

31

0

11

26

129

0

0

1 

2)

= AGGREGATE LOSSES

NO. 

:ONTS. ALE DWEL. 1 

(18) (19) (20)

5

0

0

5

0

39

35

1

0

0

0

4

125

0

0

0

12

0

4

0

0

0

0

0

0

0

0

0

0

0

11

0

0

22

0

2

0

1

0

0

0

0

21

0

0

0

5

0

0

0

0

0

0

0

0

0

1

0

0

0

2

0

0

0

0

0

0

0

0

0

0

0

1

0

0

0

0

0

0

0

0

0

0

0

0

0

0

1

0

0

BEFORE DEDUCTIBLE x $1 

HO COVER "" > <= 

NO. 

3LDG. CONTS. ALE DWEL. 

(21) (22) (23) (24)

4

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

3

0

0

10

2

4

21

6

1

0

0

3

19

0

0

0

2

3

10

1

3

0

0

2

0

1

1

7

0

0

- EO+HO COVE

BLDG. CONT

(25) (26

165

0

0

496

57

55

1,326

86

16

0

0

59

676

0

0

0

54

43

185

12

52

0

0

31

0

11

26

129

0

0

3

3

12
Table 44. Building, contents, and Ale losses, before and after deductible Continued

DATA FILE STATE-6A.DAT DISTRIBUTION OF BUILDING AND CONTENTS LOSSES BY ZIP DATA IN ZIP-FAULT ORDER (Column 2) 

ALAMEDA. CONTRA COSTA. MARIN. MONTEREY, SAN BENITO, SAN FRANCISCO, SAN MATED, SANTA CLARA, and SANTA CRUZ Counties

0.

o

)ile Home M

o

1*

i

O

c

n

1

n

00

o

3

u o 1'

n

SL

C

F

c

§r

V§ '

3

m

3 § 

1.5*

§

p-

§

m

ft1'

I

CO

vj

ZIP 

FAULT 

ZIP DIST.

(1) (2)

94403 29.9

94404 29.9

94587 30.1

93924 30.4

94019 30.7

94402 31.1

93926 32.4

94401 32.4

94545 33.0

94544 33.3

94018 33.6

94010 33.8

94542 34.7

94586 34.8

94540 35.1

94038 35.7

94541 35.8

94580 36.2

94030 36.3

94037 36.6

94566 36.8

94579 37.3

95043 37.5

94546 37.8

94578 38.0

94066 38.5

94568 39.2

93960 39.3

94550 39.6

94044 39.8

DWEL. CONTS. <= PAID LOSS UNDER EQ COVER => < PAID LOSS UNDER HO COVER => 

NO. VALUE VALUE NO. PCT. DWEL. CONTS. ALE NO. PCT. DWEL. CONTS. ALE 

DWEL. x$H1l. x$Hi1. DWEL. DWEL. x$1000 x$1000 x$1000 DWEL. DWEL. x$1000 x$1000 x$1000

(3)

747

1.022

834

105

242

588

10

210

390

593

83

805

274

18

1

81

483

513

493

90

1,681

415

1

855

437

568

530

6

1.362

671

(4)

116

184

105

19

41

109

1

27

45

65

14

222

47

4

0

15

59

55

82

15

280

45

0

114

51

77

75

1

183

88

(5)

85

137

77

14

30

81

1

19

32

47

10

167

35

3

0

11

43

40

60

11

210

33

0

84

37

55

56

0

138

62

(6)

11

15

1

3

3

5

1

14

2

2

1

13

2

0

0

1

3

2

1

0

5

1

0

6

3

3

1

0

1

0

(7)

1.5

1.5

0.1

2.9

1.2

0.9

10.0

6.7

0.5

0.3

1.2

1.6

0.7

0.0

0.0

1.2

0.6

0.4

0.2

0.0

0.3

0.2

0.0

0.7

0.7

0.5

0.2

0.0

0.1

0.0

(8)

118

213

10

35

12

35

10

324

2

6

1

550

13

0

0

4

8

13

1

0

36

3

0

51

24

17

3

0

1

0

(9) (10) (11)

27

209

0

13

2

0

0

153

1

0

0

9

0

0

0

0

0

0

2

0

3

0

0

1

5

0

0

0

0

0

0

14

0

6

1

0

2

10

0

0

0

5

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

1

0

0

0

0

0

0

0

1

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

(12) (13) (14)

0.0

0.1

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.2

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0

0

0

0

0

0

0

0

0

1

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

(15)

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

<lllll "" I 

NO. 

DWEL.

(16)

11

15

1

3

3

5

1

14

2

2

1

13

2

0

0

1

3

2

1

0

5

1

0

6

3

3

1

0

1

0

»rri nrri »Tr i nccrc orcnor

- EQ COVER > < HO COVER > < EQ+HO C

NO. NO. 

BLDG. CONTS. ALE DWEL. BLDG. CONTS. ALE DWEL. BLDG. C

(17)

268

453

20

70

43

91

20

604

22

26

11

899

38

0

0

23

38

33

11

0

90

13

0

120

61

52

15

0

16

0

(18)

27

209

0

13

2

0

0

153

1

0

0

9

0

0

0

0

0

0

2

0

3

0

0

1

5

0

0

0

0

0

(19) (20)

0

14

0

6

1

0

2

10

0

0

0

5

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

1

0

0

0

0

0

0

0

1

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

(21)

0

0

0

0

0

0

0

0

0

1

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

(22)

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

(23)

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

(24)

11

15

1

3

3

5

1

14

2

2

1

13

2

0

0

1

3

2

1

0

5

1

0

6

3

3

1

0

1

0

(25)

268

453

20

70

43

91

20

604

22

28

11

899

38

0

0

23

38

33

11

0

90

13

0

120

61

52

15

0

16

0
Table 44. Building, contents, and Ale losses, before and after deductible Continued

8. 5*

of Earthq

g5"

o

$

o

X

o

i.

3

era

5'

£

f

35*

ALAMEDA. CONTRA COSTA, MARIN, MONTEREY.

ZIP 

FAULT

ZIP DIST.

(1) (2)

94552 39.8

94080 40.4

94603 40.9

94005 41.1

94583 41.5

94621 42.3

94605 42.5

94015 43.2

94014 43.5

94134 43.6

94501 43.7

94124 44.0

94601 44.1

94619 44.3

94112 44.5

94620 45.2

94602 45.4

94606 45.4

94132 45.6

94110 45.7

94526 45.8

94127 45.9

94131 45.9

94107 46.0

94516 46.2

94114 46.6

94610 46.6

94612 46.6

94607 46.8

94101 46.9

NO.

rnu \*UYt.i\ " -

DWEL. CONTS. < 

VALUE VALUE

DWEL. x$Mil. x$Mil.

(3)

239

662

120

33

1,120

82

481

771

197

155

728

62

109

318

429

1

382

50

142

205

1,363

332

359

53

5

262

239

1

22

1

(4)

42

86

11

5

192

7

64

99

26

20

118

8

11

47

54

0

56

6

22

32

314

61

60

9

1

59

47

0

2

0

(5)

31

60

7

3

145

5

45

70

17

13

86

5

7

33

35

0

39

4

15

22

238

42

43

7

0

41

33

0

2

0

SAN BENITO, SAN FRANCISCO. SAN MATED, SANTA CLARA, and SANTA CRUZ Counties

y= PAID LOSS UNDER EQ COVER »=> <= PAID LOSS UNDER HO COVER ==> 

NO. PCT. DWEL. CONTS. ALE NO. PCT. DWEL. CONTS. ALE

DWEL.

(6)

0

1

3

0

6

4

20

2

2

0

5

2

3

6

12

0

3

1

0

2

9

9

4

1

0

5

7

0

4

0

DWEL.

(7)

0.0

0.2

2.5

0.0

0.5

4.9

4.2

0.3

1.0

0.0

0.7

3.2

2.8

1.9

2.8

0.0

0.8

2.0

0.0

1.0

0.7

2.7

1.1

1.9

0.0

1.9

2.9

0.0

18.2

0.0

x$1000

(8)

0

6

4

0

36

168

354

5

2

0

29

72

43

76

204

0

61

3

0

129

176

183

73

25

0

33

173

0

43

0

«. . 

NO.

x$1000 x$1000 DWEL. DWEL. x$1000 x$1000 x$1000 DWEL.

(9) (10) (11) (12) (13) (14) (15)

0 0 0 0.0 0 00

4 0 0 0.0 0 00

0 0 0 0.0 0 00

0 0 0 0.0 0 00

0 0 0 0.0 0 00

0 12 1 1.2 1 00

4 0 1 0.2 1 00

6 0 1 0.1 0 00

2 0 0 0.0 0 00

0 0 0 0.0 0 00

0 0 0 0.0 0 00

2 0 0 0.0 0 00

0 0 0 0.0 0 00

2 0 0 0.0 0 00

33 10 1 0.2 1 00

0 0 0 0.0 0 00

0 0 0 0.0 0 00

3 0 0 0.0 0 00

0 0 0 0.0 0 00

0 5 0 0.0 0 00

4 0 0 0.0 0 00

34 6 0 0.0 0 00

1 0 0 0.0 0 00

0 2 0 0.0 0 00

0 0 0 0.0 0 00

0 0 0 0.0 0 , 00

2 3 0 0.0 0 00

0 0 0 0.0 0 00

2 1 0 0.0 0 00

0 0 0 0.0 0 00

(16)

0

1

3

0

6

4

20

2

2

0

5

2

3

6

12

0

3

1

0

2

9

9

4

1

0

5

7

0

4

0

 EQ COVER > < HO COVER ==> < - EQ+HO COV

NO. NO.

BLDG.

(17)

0

19

34

0

121

195

568

26

22

0

97

92

73

142

337

0

91

13

0

166

279

293

121

43

0

93

233

0

84

0

CONTS.

(18)

0

4

0

0

0

0

4

6

2

0

0

2

0

2

33

0

0

3

0

0

4

34

1

0

0

0

2

0

2

0

ALE DWEL.

(19)

0

0

0

0

0

12

0

0

0

0

0

0

0

0

10

0

0

0

0

5

0

6

0

2

0

0

3

0

1

0

(20)

0

0

0

0

0

1

1

1

0

0

0

0

0

0

1

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

BLDG. CONTS.

(21) (22)

0 0

0 0

0 0

0 0

0 0

1 0

1 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

1 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

ALE

(23)

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

DWEL.

(24)

0

1

3

0

6

4

20

2

2

0

5

2

3

6

12

0

3

1

0

2

9

9

4

1

0

5

7

0

4

0

BLDG.

(25)

0

19

34

0

121

196

569

26

22

0

97

92

73

142

338

0

91

13

0

166

279

293

121

43

0

93

233

0

84

0

CON

(2
Dwelling andMob

ile Home Mone

if

ri

o

n

9

3-

n

^

eo

o

 o

asr

n

Si.

g

-F

m

S>

.O

(v1

j.

Lt

3

m

 o

1*.

35*

O

p8t/1

m

3*

&

o

3

CO

Table 44. Building, contents, and Ale losses, before and after deductible Contmuet

DATA FILE STATE-6A.DAT DISTRIBUTION OF BUILDING AND CONTENTS LOSSES BY ZIP DATA IN ZIP-FAULT ORDER (Column 

ALAMEDA, CONTRA COSTA, MARIN, MONTEREY, SAN BENITO. SAN FRANCISCO, SAN MATED, SANTA CLARA, and SANTA CRUZ Counties

ZIP 

FAULT 

ZIP DIST. 

(1) (2)

94119 46.9

94128 46.9

94139 46.9

94146 46.9

94103 47.0

94116 47.2

94611 47.4

94102 47.6

94117 47.6

94556 47.6

94105 47.7

94122 48.0

93920 48.1

94108 48.2

94507 48.2

93927 48.3

94109 48.3

94115 48.4

94609 48.4

94133 48.6

94528 48.6

94608 48.6

94118 48.7

94618 48.7

94123 49.2

94121 49.3

94129 49.6

94595 49.7

94705 49.7

94563 50.3

DWEL. CONTS. <= PAID LOSS UNDER EQ COVER ==> <= PAID LOSS UNDER HO COVER => 

NO. VALUE VALUE NO. PCT. DWEL. CONTS. ALE NO. PCT. DWEL. CONTS. ALE 

DWEL. x$Mil. x$Mil. DWEL. DWEL. x$1000 x$ 1 000 x$ 1000 DWEL. DWEL. x$1000 x$1000 xJlOOO 

(3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15)

1

2

1

1

8

388

700

3

106

574

1

351

18

3

290

16

22

68

72

22

26

45

142

286

66

184

1

177

286

580

0

1

0

0

1

58

142

1

27

123

0

54

5

1

77

1

9

23

8

7

7

5

41

51

23

36

0

33

65

140

0

0

0

0

1

39

100

0

19

94

0

36

3

0

59

1

7

16

6

5

5

3

28

36

16

25

0

25

45

105

0

1

0

0

0

8

4

0

8

1

0

27

0

0

1

0

0

5

1

0

0

4

16

2

15

15

0

2

4

4

0.0

50.0

0.0

0.0

0.0

2.1

0.6

0.0

7.5

0.2

0.0

7.7

0.0

0.0

0.3

0.0

0.0

7.4

1.4

0.0

0.0

8.9

11.3

0.7

22.7

8.2

0.0

1.1

1.4

0.7

0

7

0

0

0

249

197

0

66

8

0

469

0

0

23

0

0

145

27

0

0

8

301

9

454

282

0

75

101

99

0

0

0

0

0

5

21

0

10

0

0

116

0

0

0

0

0

4

0

0

0

9

20

0

29

16

0

0

0

0

0

0

0

0

0

6

16

0

1

0

0

1

0

0

0

0

0

0

9

0

0

0

0

0

5

3

0

0

0

3

0

0

0

0

0

0

0

0

0

0

0

2

0

0

0

0

0

0

0

0

0

0

0

0

1

2

0

0

0

0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.6

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

1.5

1.1

0.0

0.0

0.0

0.0

0

0

0

0

0

0

0

0

0

0

0

13

0

0

0

0

0

0

0

0

0

0

0

0

0

10

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

<lllll III""* 

NO. 

DWEL. 

(16)

0

1

0

0

0

8

4

0

8

1

0

27

0

0

1

0

0

5

1

0

0

4

16

2

15

15

0

2

4

4

1

2)

» AprorpATr i ncccc ocrnoc

- EQ COVER > ; HO COVER = > <== EO+HO C

NO. NO. 

BLDG. CONTS. ALE DWEL. BLDG. CONTS. ALE DWEL. BLDG. C

(17) (18) (19) (20) (21) (22) (23) (24) (25) 

0

17

0

0

0

362

307

0

187

25

0

886

0

0

33

0

0

235

39

0

0

48

516

30

811

834

0

105

142

144

0

0

0

0

0

5

21

0

10

0

0

116

0

0

0

0

0

4

0

0

0

9

20

0

29

16

0

0

0

0

0

0

0

0

0

6

16

0

1

0

0

1

0

0

0

0

0

0

9

0

0

0

0

0

5

3

0

0

0

3

0

0

0

0

0

0

0

0

0

0

0

2

0

0

0

0

0

0

0

0

0

0

0

0

1

2

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

13

0

0

0

0

0

0

0

0

0

0

0

0

0

10

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

1

0

0

0

8

4

0

8

1

0

27

0

0

1

0

0

5

1

0

0

4

16

2

15

15

0

2

4

4

0

17

0

0

0

362

307

0

187

25

0

899

0

0

33

0

0

235

39

0

0

48

516

30

811

844

0

105

142

144
Table 44. Building, contents, and Ale losses, before and after deductible Continued

DATA FILE STATE-6A.DAT DISTRIBUTION OF BUILDING AND CONTENTS LOSSES BY ZIP DATA IN ZIP-FAULT ORDER (Column 2) 

ALAMEDA. CONTRA COSTA. MARIN, MONTEREY, SAN BENITO. SAN FRANCISCO, SAN MATED. SANTA CLARA, and SANTA CRUZ Counties |-

jf Earthquake 1

i

sX

o 

5

cf

5*

na>

f35*

ZIP 

FAULT 

ZIP DIST. 

(1) (2)

94704 50.3

94703 50.4

94702 50.7

94549 51.2

94709 51.2

94710 51.3

94594 51.6

94596 51.7

94708 52.3

94598 52.7

94707 52.7

94517 53.8

94514 54.2

94530 54.4

94965 54.7

94518 54.9

94523 54.9

94521 55.5

94804 55.5

94920 55.8

94805 56.3

94801 56.8

94520 57.0

94808 57.1

94513 57.2

94519 57.2

94803 57.7

94941 57.7

94942 57.7

94553 58.0

DWEL. CONTS. <-= PAID LOSS UNDER EQ COVER => < PAID LOSS UNDER HO COVER => 

NO. VALUE VALUE NO. PCT. DWEL. CONTS. ALE NO. PCT. DWEL. CONTS. ALE 

DWEL. x$Mil. x$M11. DWEL. DWEL. x$ 1000 x$1000 x$1000 DWEL. DWEL. x$1000 x$1000 x$1000 

(3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15)

48

116

115

671

93

20

1

492

526

584

514

201

93

554

105

397

491

651

243

176

254

78

145

1

103

209

657

526

1

660

9

15

14

147

16

3

0

83

102

105

98

34

17

81

25

58

70

92

25

48

29

10

16

0

12

25

92

109

0

90

6

10

9

111

11

2

0

62

74

79

69

26

13

58

18

43

52

68

17

36

20

7

11

0

9

18

67

80

0

66

0

0

2

8

1

0

0

2

7

0

8

0

0

4

2

1

2

2

4

0

1

0

0

0

0

0

3

2

0

2

0.0

0.0

1.7

1.2

1.1

0.0

0.0

0.4

1.3

0.0

1.6

0.0

0.0

0.7

1.9

0.3

0.4

0.3

1.6

0.0

0.4

0.0

0.0

0.0

0.0

0.0

0.5

0.4

0.0

0.3

0

0

33

129

4

0

0

11

173

0

146

0

0

82

8

7

57

11

10

0

3

0

0

0

0

0

42

7

0

7

0

0

3

1

0

0

0

0

0

0

0

0

0

1

52

0

1

0

0

0

1

0

0

0

0

0

13

0

0

1

0

0

0

4

0

0

0

0

2

0

3

0

0

5

0

0

7

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

1

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

1.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

35

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

<< II 

NO. 

DWEL. 

(16)

0

0

2

8

1

0

0

2

7

0

8

0

0

4

2

1

2

2

4

0

1

0

0

0

0

0

3

2

0

2

- EQ COVER ==> < =» HO COVER > «s EO+HO C

NO. NO. 

BLDG. CONTS. ALE DWEL. BLDG. CONTS. ALE DWEL. BLDG. C

(17) (18) (19) (20) (21) (22) (23) (24) (25) 

0

0

53

268

14

0

0

31

298

0

270

0

0

142

63

17

86

37

52

0

13

0

0

0

0

0

79

27

0

37

0

0

3

1

0

0

0

0

0

0

0

0

0

1

52

0

1

0

0

0

1

0

0

0

0

0

13

0

0

1

0

0

0

4

0

0

0

0

2

0

3

0

0

5

0

0

7

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

35

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

2

8

1

0

0

2

7

0

8

0

0

4

2

1

2

2

4

0

1

0

0

0

0

0

3

2

0

2

0

0

53

268

14

0

0

31

298

0

270

0

0

142

63

17

86

37

52

0

13

0

0

0

0

0

79

27

0

37
Table 44. Building, contents, and Ale losses, before and after deductible Continued

OQ 

W

a.

o

DATA FILE STATE-6A.DAT DISTRIBUTION OF BUILDING AND CONTENTS LOSSES BY ZIP DATA IN ZIP-FAULT ORDER (Column Z) 

ALAMEDA. CONTRA COSTA. HARIN. MONTEREY. SAN BENITO. SAN FRANCISCO. SAN MATED. SANTA CLARA, and SANTA CRUZ Counties

n

_* 

10 

oo 

«

n

Si. 

f

3

JO

w5"

i1

 §-

ZIP 

FAULT 

ZIP DIST.

(1) (2)

94806 5B.5

94925 58.7

94564 59.2

94964 59.2

94547 59.4

94509 59.6

93930 59.7

94565 60.0

94548 60.1

94939 60.2

94561 60. B

94904 61.0

94970 61.2

94572 61.4

94569 62.0

94901 62.0

94525 62.5

94957 62.5

94924 62. B

94915 63.1

94510 63.2

94960 64.2

94930 64.8

94511 65.4

94903 65.4

94591 65.7

94590 66.4

94963 67. B

94973 67.8

94949 67.9

DWEL. CONTS. < PAID LOSS UNDER EQ COVER > < PAID LOSS UNDER HO COVER -=> 

NO. VALUE VALUE NO. PCT. DWEL. CONTS. ALE NO. PCT. DWEL. CONTS. ALE 

DWEL. xSHil. x$H11. DWEL. DWEL. xllOOO xllOOO x$1000 DWEL. DWEL. x$ 1000 xllOOO xllOOO

(3)

476

136

383

1

252

727

29

698

2

B2

163

160

24

92

4

376

30

34

30

1

2

240

123

14

360

1

1

12

40

148

(4) (5)

52

20

49

0

36

90

3

77

0

16

19

38

4

11

0

78

4

11

5

0

0

42

IB

2

56

0

0

2

6

29

36

15

36

0

26

67

2

56

0

12

14

29

3

8

0

59

3

B

4

0

0

31

13

1

42

0

0

2

5

22

(6)

2

2

6

0

0

0

0

2

0

0

0

0

0

0

0

3

1

0

0

0

0

1

0

0

0

0

0

0

0

0

(7)

0.4

1.5

1.6

0.0

0.0

0.0

0.0

0.3

0.0

0.0

0.0

0.0

0.0

0.0

0.0

O.B

3.3

0.0

0.0

0.0

0.0

0.4

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

(B) (9) (10) (11)

14

29

46

0

0

0

0

2

0

0

0

0

0

0

0

14

1

0

0

0

0

13

0

0

0

0

0

0

0

0

B

0

0

0

0

0

0

0

0

0

0

0

0

0

0

10

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

(12) (13) (14)

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

(15)

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

<jmiLj]

NO. 

DWEL.

(16)

2

2

6

0

0

0

0

2

0

0

0

0

0

0

0

3

1

0

0

0

0

1

0

0

0

0

0

0

0

0

- EQ COVER > : HO COVER > ; EQ+HO 

NO. NO. 

BLD6. CONTS. ALE DWEL. BLD6. CONTS. ALE DWEL. BLDG. 

(17)

34

56

109

0

0

0

0

22

0

0

0

0

0

0

0

54

11

0

0

0

0

24

0

0

0

0

0

0

0

0

(18) (19) (20)

B

0

0

0

0

0

0

0

0

0

0

0

0

0

0

10

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

(21)

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

(22)

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

(23)

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

(24)

2

2

6

0

0

0

0

2

0

0

0

0

0

0

0

3

1

0

0

0

0

1

0

0

0

0

0

0

0

0

(25)

34

56

109

0

0

0

0

22

0

0

0

0

0

0

0

54

11

0

0

0

0

24

0

0

0

0

0

0

0

0
B72 Estimation ol

m

V

f 

£5"

fD

8

n

(A

s

I

§

 .

OQ

3*

n

2L

 S

o

355°

Table 44. Building, contents, and Ale losses, before and after deductible Continued

DATA FILE STATE-6A.DAT DISTRIBUTION OF BUILDING AND CONTENTS LOSSES BY ZIP DATA IN ZIP-FAULT ORDER (Column 2) 

ALAMEDA, CONTRA COSTA, MARIN, MONTEREY, SAN BENITO. SAN FRANCISCO, SAN MATED. SANTA CLARA, and SANTA CRUZ Counties

ZIP 

FAULT 

ZIP DIST.

(1) (2)

945B9 69.2

94933 69.2

94938 69.4

94947 71.3

94950 71.7

94945 72.1

94946 73.0

94533 76.6

94956 76.6

94535 76.7

93932 78.1

94937 78.3

94952 B1.9

94940 82.1

94928 B9.2

94929 90.1

 > c. VJTRU i/ v/ Y 1. 1\ -- *

DUEL. CONTS. < 

NO. VALUE VALUE 

DUEL. xSHil. xSHil.

(3)

1

9

11

371

2

255

8

1

15

1

2

33

3

7

1

8

(4)

0

1

2

60

0

44

3

0

2

0

0

5

0

1

0

1

(5)

0

1

1

45

0

34

2

0

2

0

0

3

0

1

0

1

3 PAID LOSS UNDER EQ COVER -=> < PAID LOSS UNDER HO COVER => 

NO. PCT. DUEL. CONTS. ALE NO. PCT. DUEL. CONTS. ALE 

DUEL. DUEL. xllOOO xJlOOO xllOOO DUEL. DUEL. xllOOO xllOOO x$1000

(6)

0

0

0

0

0

2

0

0

0

0

0

0

0

0

0

0

(7)

0.0

0.0

0.0

0.0

0.0

O.B

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

(8)

0

0

0

0

0

3'

0

0

0

0

0

0

0

0

0

0

(9) (10) (11) (12)

0 0 0 0.0

0 0 0 0.0

0 0 0 0.0

0 0 0 0.0

0 0 0 0.0

0 0 0 0.0

0 0 0 0.0

0 0 0 0.0

0 0 0 0.0

0 0 0 0.0

0 0 0 0.0

0 0 0 0.0

0 0 0 0.0

0 0 0 0.0

0 0 0 0.0

0 0 0 0.0

(13) (14)

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

(15)

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

<Jum»»u

NO. 

DUEL.

(16)

0

0

0

0

0

2

0

0

0

0

0

0

0

0

0

0

» EQ COVER ==> : HO COVER «=> <~ EO+HO C

NO. NO. 

BLDG. CONTS. ALE DUEL. BLDG. CONTS. ALE DUEL. BLDG. C

(17)

0

0

0

0

0

39

0

0

0

0

0

0

0

0

0

0

(18)

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

(19)

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

(20)

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

(21)

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

(22)

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

(23) (24)

0 0

0 0

0 0

0 0

0 0

0 2

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

(25)

0

0

0

0

0

39

0

0

0

0

0

0

0

0

0

0

84,423 13,520 9.9B7 2.784 63,985 14,885 5.159 245 2.391 467 115 2,784 114,864 14.885 5,159 230 1,941 467 115 3.014 116.805 15

NOTES:

Column 7: PCT. DUEL. - Column 6 divided by column 3. in *.

Column 12: PCT. DUEL. - Colunn 11 divided by column 3 in *.

Column 28: BLDG. XLOSS - Average building loss as a * of insured value, before deductible.

Column 17 divided by column 4. in X. 

Column 29: CONTS. RATIO * (Aggregate contents loss [column 26])

divided by (Aggregate building loss before deductible [column 25]). 

Column 30: ALE RATIO - (Aggregate ALE loss [has no deductible - column 27]) divided by

(Aggregate building loss before deductible [column 25]).