SPECIAL PUBLICATION 42 

Interim Revision 2007 

FAULT-RUPTURE HAZARD ZONES

IN CALIFORNIA

Alquist-Priolo Earthquake Fault Zoning Act

with Index to Earthquake Fault Zones1 Maps

1 Name changed from Special Studies Zones January 1, 1994

DEPARTMENT OF CONSERVATION

California Geological Survey

STATE OF CALIFORNIA

ARNOLD SCHWARZENEGGER

GOVERNOR

 THE RESOURCES AGENCY DEPARTMENT OF CONSERVATION

 MIKE CHRISMAN BRIDGETT LUTHER

SECRETARY FOR RESOURCES DIRECTOR

CALIFORNIA GEOLOGICAL SURVEY

JOHN G. PARRISH, PH.D. 

STATE GEOLOGIST
SPECIAL PUBLICATION 42

FAULT-RUPTURE HAZARD ZONES IN CALIFORNIA

Alquist-Priolo Earthquake Fault Zoning Act

With Index to Earthquake Fault Zones Maps

by

WILLIAM A. BRYANT and EARL W. HART

Geologists

Interim Revision 2007

California Department of Conservation

California Geological Survey

801 K Street, MS 12-31

Sacramento, California 95814
PREFACE

The purpose of the Alquist-Priolo Earthquake Fault Zoning Act is to regulate development near 

active faults so as to mitigate the hazard of surface fault rupture.

This report summarizes the various responsibilities under the Act and details the actions taken by

the State Geologist and his staff to implement the Act.

This is the eleventh revision of Special Publication 42, which was first issued in December 1973 as an 

“Index to Maps of Special Studies Zones.” A text was added in 1975 and subsequent revisions were 

made in 1976, 1977, 1980, 1985, 1988, 1990, 1992, 1994, and 1997. The 2007 revision is an interim 

version, available in electronic format only, that has been updated to reflect changes in the index map 

and listing of additional affected cities. In response to requests from various users of Alquist-Priolo 

maps and reports, several digital products are now available, including digital raster graphic (pdf) and 

Geographic Information System (GIS) files of the Earthquake Fault Zones maps, and digital files of Fault 

Evaluation Reports and site reports submitted to the California Geological Survey in compliance with the 

Alquist-Priolo Act (see Appendix E).

On January 1, 1994, the name of the Alquist-Priolo Special Studies Zones Act was changed to the 

Alquist-Priolo Earthquake Fault Zoning Act, and the name Special Studies Zones was changed to 

Earthquake Fault Zones as a result of a July 25, 1993 amendment.

Information on new and revised Earthquake Fault Zones maps will be provided as supplements until 

the next revision of this report.
CALIFORNIA DEPARTMENT OF CONSERVATION

CALIFORNIA GEOLOGICAL SURVEY

801 K Street, MS 12-31

Sacramento, CA 95814-3531

www.conservation.ca.gov/cgs

PUBLIC INFORMATION OFFICES:

SACRAMENTO AREA SAN FRANCISCO AREA LOS ANGELES AREA

Publications and Information 345 Middlefield Road, MS 520 888 South Figueroa, Suite 475

801 K Street, MS 14-33 Menlo Park, CA 94025 Los Angeles, CA 90017

Sacramento, CA 95814-3532 (650) 688-6327 (213) 239-0878

(916) 445-5716

SUPPLEMENT NO. 1 TO SPECIAL PUBLICATION 42 (2007 Interim Edition)

NEW AND REVISED OFFICIAL MAPS OF EARTHQUAKE FAULT ZONES OF SEPTEMBER 21, 2012

Official Maps of new and revised Earthquake Fault Zones, indexed hereon, are issued pursuant to the 

Alquist-Priolo Earthquake Fault Zoning Act. Revised maps supersede earlier Official Maps.

Copies of these maps may be examined at the offices of affected cities and counties, at the Public 

Information offices of the California Geological Survey (CGS), and on the CGS website 

(http://www.quake.ca.gov/gmaps/ap/ap_maps.htm). Both GIS and pdf files can be downloaded from this 

website. Printed maps may be purchased from ARC-Bryant (formerly BPS Reprographic Services), 945 Bryant 

Street, San Francisco, California 94103, telephone (415) 495-8700.

For information on Official Maps of Earthquake Fault Zones previously issued, and for provisions of the 

Alquist-Priolo Earthquake Fault Zoning Act, the reader should consult the 2007 edition of Special Publication 42, 

“Fault-rupture Hazard Zones in California.” This publication is available online only from the California 

Geological Survey at ftp://ftp.consrv.ca.gov/pub/dmg/pubs/sp/Sp42.pdf.

Official Maps issued September 21, 2012 (Map numbers keyed to index map):

1. Hayward.*

2. Piru

3. Mecca*

4. Mortmar*

5. Orocopia Canyon*

6. Salton*

7. Durmid*

8. Carrizo Mtn.*

9. Painted Gorge

10. Plaster City

11. Coyote Wells

12. Yuha Basin

13. Mount Signal

_______________

* Revised zone map

Cities and counties affected by new or revised Earthquake Fault Zones shown on Official Maps of September 19, 

2012:

Cities Counties

Hayward Alameda

Oakland Imperial

San Leandro Riverside

San Diego

Ventura
SUPPLEMENT NO. 1 INDEX MAP

NEW AND REVISED OFFICIAL MAPS OF EARTHQUAKE FAULT ZONES OF SEPTEMBER 21, 2012

(See List for Names of Maps)

1

Contra

Costa

Alameda

San

Mateo

Santa

Clara

2 Los

Angeles

Kern

Ventura

1213

7

8

11

9 10

Imperial

Riverside

3 4 5

6

San Diego
CONTENTS

INTRODUCTION........................................................................................................................................... 1

PROGRAM FOR ZONING AND EVALUATING FAULTS........................................................................... 2

Requirements of the Act ......................................................................................................................................... 2 

Initial Program for Zoning Faults ............................................................................................................................. 2 

Definitions, Policies, Rationale................................................................................................................................ 3 

 Fault and Fault Zone........................................................................................................................................ 3 

Fault Trace....................................................................................................................................................... 5 

Active Fault...................................................................................................................................................... 5 

Potentially Active Fault..................................................................................................................................... 5 

 Sufficiently Active and Well-Defined ................................................................................................................ 5 

Delineating the Earthquake Fault Zones................................................................................................................. 6 

Fault Evaluation and Zoning Program..................................................................................................................... 6 

Uses and Limitations of Earthquake Fault Zones Maps.......................................................................................... 9 

INDEX TO MAPS OF EARTHQUAKE FAULT ZONES............................................................................... 9

Availability of Earthquake Fault Zones Maps .......................................................................................................... 9 

REFERENCES.............................................................................................................................................10

APPENDICES..............................................................................................................................................22

Appendix A. Alquist-Priolo Earthquake Fault Zoning Act .....................................................................................22

Appendix B. Policies and Criteria of the State Mining and Geology Board ........................................................... 26 

Appendix C. Guidelines for Evaluating the Hazard of Surface Fault Rupture ...................................................... 28 

 Appendix D. General Guidelines for Reviewing Geologic Reports........................................................................ 33 

Appendix E. Products of the Fault Evaluation and Zoning Program .................................................................... 36 

Appendix F. Waiver Procedure for the Alquist-Priolo Act.....................................................................................42

TABLES

Table 1. Summary of responsibilities and functions under the Alquist-Priolo Earthquake Fault 

 Zoning Act ................................................................................................................................................ 1 

Table 2. Summary of policies and criteria adopted by the State Mining and Geology Board 

and codified in California Code of Regulations ......................................................................................... 2 

Table 3. Official Maps of Earthquake Fault Zones issued 1974 through 2007....................................................... 2 

Table 4. Cities and counties affected by Earthquake Fault Zones as of August 2007 ........................................... 3 

Table 5. Surface faulting associated with earthquakes in California, 1974-June 2007 .......................................... 8 

FIGURES

Figure 1. Principal active faults in California zoned under the Alquist-Priolo Earthquake

Fault Zoning Act...................................................................................................................................... 4 

Figure 2. Geologic time scale................................................................................................................................. 5 

Figure 3. Example of Earthquake Fault Zones Map............................................................................................... 7 

Figure 4. Index to Official Maps of Earthquake Fault Zones ........................................................................... 11-21
FAULT-RUPTURE HAZARD ZONES

IN CALIFORNIA

By

William A. Bryant and Earl W. Hart

INTRODUCTION

The Alquist-Priolo Earthquake Fault Zoning Act was 

signed into law December 22, 1972, and went into effect March 7, 

1973. The Act, codified in the Public Resources Code as 

Division 2, Chapter 7.5, has been amended ten times. A complete 

text of the Act is provided in Appendix A. The purpose of this 

Act is to prohibit the location of most structures for human 

occupancy across the traces of active faults and to thereby 

mitigate the hazard of fault rupture (Section 2621.5).

This law initially was designated as the Alquist-Priolo 

Geologic Hazard Zones Act. The Act was renamed the AlquistPriolo Special Studies Zones Act effective May 4, 1975 and the 

Alquist-Priolo Earthquake Fault Zoning Act effective January 1, 

1994. The original designation “Special Studies Zones” was 

changed to “Earthquake Fault Zones” when the Act was last 

renamed.

Under the Act, the State Geologist (Chief of the 

California Geological Survey [CGS]) is required to delineate 

“Earthquake Fault Zones” (EFZs) along known active faults in 

California. Cities and counties affected by the zones must 

regulate certain development “projects” within the zones. They 

must withhold development permits for sites within the zones 

until geologic investigations demonstrate that the sites are not 

threatened by surface displacement from future faulting. The 

State Mining and Geology Board provides additional regulations 

(Policies and Criteria) to guide cities and counties in their 

implementation of the law (California Code of Regulations, Title 

14, Div. 2). A summary of principal responsibilities and 

functions required by the Alquist-Priolo Act is given in Table 1. 

The Policies and Criteria are summarized in Table 2, and the 

complete text is provided in Appendix B.

This publication identifies and describes (1) actions taken 

by the State Geologist to delineate Earthquake Fault Zones, (2) 

policies used to make zoning decisions, and (3) Official Maps of 

Earthquake Fault Zones issued to date. A continuing program to 

evaluate faults for future zoning or zone revision also is 

summarized. Other aspects of the Alquist-Priolo Earthquake 

Fault Zoning Act and its implementation are discussed by Hart 

(1978 and 1986). The effectiveness of the AP Act and program 

was evaluated by Reitherman and Leeds (1990). The program is 

implementing many of the recommendations in that report.

Information presented here is based on various in-house 

documents and publications of the authors and others of the CGS

(see Appendix E). 
2 CALIFORNIA GEOLOGICAL SURVEY SP42

PROGRAM FOR ZONING AND EVALUATING 

FAULTS

Requirements of the Act

Section 2622 of the Alquist-Priolo Earthquake Fault 

Zoning Act (Appendix A) requires the State Geologist to:

1. “Delineate ... appropriately wide earthquake fault 

zones to encompass all potentially and recently active traces of 

the San Andreas, Calaveras, Hayward, and San Jacinto faults, 

and such other faults, or segments thereof, as the State 

Geologist determines to be sufficiently active and well-defined 

as to constitute a potential hazard to structures from surface 

faulting or fault creep.”

2. Compile maps of Earthquake Fault Zones and submit 

such maps to affected cities, counties, and state agencies for 

their review and comment. Following appropriate reviews, 

the State Geologist must provide Official Maps to the affected 

cities, counties, and state agencies.

3. Continually review new geologic and seismic data to 

revise the Earthquake Fault Zones or delineate additional 

zones.

These requirements constitute the basis for the State 

Geologist’s fault-zoning program and for many of the policies 

devised to implement the program.

Initial Program for Zoning Faults

As required under the Act, the State Geologist initiated a 

program early in 1973 to delineate Earthquake Fault Zones to 

encompass potentially and recently active traces of the San 

Andreas, Calaveras, Hayward, and San Jacinto faults, and to 

compile and distribute maps of these zones. A project team 

was established within the CGS to develop and conduct a 

program for delineation of the zones.

Initially, 175 maps of Earthquake Fault Zones were 

delineated for the four named faults. These zone maps, issued 

as Preliminary Review Maps, were distributed for review by 

local and state government agencies on December 31, 1973. 

Following prescribed 90-day review and revision periods, 

Official Maps were issued on July 1, 1974. At that time, the 

Earthquake Fault Zones became effective and the affected

cities and counties were required to implement programs to 

regulate development within the mapped zones. A second set 

of Official Maps -- 81 maps of new zones and five maps of 

revised zones -- was issued on January 1, 1976 to delineate 

new and revised zones. Additional Official Maps of new and 

revised zones were issued in succeeding years, as summarized 

in Table 3.

Table 3. Official Maps of Earthquake Fault Zones issued 1974 through 

August 2007.

DATE OF ISSUE

NEW

MAPS

REVISED

MAPS

WITHDRAWN

MAPS

July 1, 1974 175 - - 

January 1, 1976 81 5 - 

January 1, 1977 4 3 - 

January 1, 1978 1 - - 

July 26, 1978 2 - - 

January 1, 1979 4 7 - 

January 1, 1980 21 9 - 

January 1, 1982 13 27 2 

July 1, 1983 18 12 - 

January 1, 1985 33 10 - 

July 1, 1986 18 14 - 

March 1, 1988 58 4 - 

January 1, 1990 60 25 - 

November 1, 1991 46 8 - 

July 1, 1993 1 10 2 

June 1, 1995 8 13 - 

May 1, 1998 2 1 - 

May 1, 1999 3 1 - 

May 1, 2003 3 11 - 

August 16, 2007 - 1 - 

Totals 551 161 4 
2007 FAULT-RUPTURE HAZARD ZONES IN CALIFORNIA 3 

As of August 16, 2007, 551 Official Maps of Earthquake 

Fault Zones have been issued. Of these, 161 have been 

revised since their initial issue and four have been withdrawn. 

The maps are identified by quadrangle map name and the date 

of issue or revision on the Index to Maps of Earthquake Fault 

Zones (Figure 4).

The maps delineate regulatory zones for the faults 

generally identified in Figure 1. Additional faults will be 

zoned in the future, and some zones will be revised. Thirtysix counties and 104 cities are affected by the existing 

Earthquake Fault Zones. These jurisdictions are listed in 

Table 4.

Definitions, Policies, Rationale

For the State Geologist to carry out the mandate to 

establish regulatory zones, certain terms identified in Section 

2622 of the Act had to be defined and policies had to be 

developed to provide a consistent and reasonable approach to 

zoning. After the zoning program was underway and the 

surface fault-rupture process was better understood, other 

terms were defined and some zoning policies were modified.

Fault and Fault Zone

A fault is defined as a fracture or zone of closely 

associated fractures along which rocks on one side have been 

displaced with respect to those on the other side. Most faults 

are the result of repeated displacement that may have taken 

place suddenly and/or by slow creep. A fault is distinguished 

from those fractures or shears caused by landsliding or other 

gravity-induced surficial failures. A fault zone is a zone of 

related faults that commonly are braided and subparallel, but 

may be branching and divergent. A fault zone has significant 

width (with respect to the scale at which the fault is being 

considered, portrayed, or investigated), ranging from a few 

feet to several miles.

Table 4. Cities and counties affected by Earthquake Fault Zones as of August 16, 2007*

CITIES (104)** COUNTIES (36)

American Canyon Hayward Rosemead Alameda Stanislaus

Arcadia Hemet San Bernardino Alpine Ventura

Arcata Highland San Bruno Butte Yolo

Arvin Hollister San Diego Contra Costa

Bakersfield Huntington Beach San Fernando Fresno

Banning Indio San Jacinto Humboldt

Barstow Inglewood San Jose Imperial

Beaumont La Habra San Juan Bautista Inyo

Benicia La Habra Heights San Leandro Kern

Berkeley Lake Elsinore San Luis Obispo Lake

Bishop Livermore San Marino Lassen

Brea Loma Linda San Pablo Los Angeles

Calimesa Long Beach San Ramon Marin

Camarillo Los Angeles Santa Clarita Mendocino

Carson Malibu Santa Rosa Merced

Cathedral City Mammoth Lakes Seal Beach Modoc

Chino Hills Milpitas Signal Hill Mono

Coachella Monrovia Simi Valley Monterey

Colton Moorpark South Pasadena Napa

Compton Moreno Valley South San Francisco Orange

Concord Morgan Hill Temecula Riverside

Corona Murrieta Trinidad San Benito

Coronado Oakland Twentynine Palms San Bernardino

Culver City Pacifica Union City San Diego

Daly City Palmdale Upland San Luis Obispo

Danville Palm Springs Ventura (San Buenaventura) San Mateo

Desert Hot Springs Palo Alto Walnut Creek Santa Barbara

Dublin Pasadena Whittier Santa Clara

El Cerrito Pleasanton Willits Santa Cruz

Fairfield Portola Valley Windsor Shasta

Fontana Rancho Cucamonga Woodside Siskiyou

Fortuna Redlands Yorba Linda Solano

Fremont Rialto Yucaipa Sonoma

Gardena Richmond Yucca Valley

Glendale Ridgecrest

* To inquire about local government policies and regulations or to consult (obtain) copies of specific Earthquake Fault Zones maps, 

address the Planning Director of each county or city. Some jurisdictions have replotted the EFZ boundaries on large-scale parcel maps.

** Additional cities may be affected by the zones as new cities are created, city boundaries are expanded, or new zones are established
4 CALIFORNIA GEOLOGICAL SURVEY SP42

MAP

SYMBOL

NAME OF

PRINCIPAL FAULT

 Faults zoned through August 2007 

 Approximate boundaries of work-plan regions and year studied

 Note: Other faults may be zoned in the future and existing zones 

 may be revised when warranted by new fault data

B *Brawley 

BS Bartlett Springs 

BV *Buena Vista 

C *Calaveras

CA Calico 

CH *Cleveland Hill 

CM Cedar Mtn. 

CU Cucamonga 

DS Deep Springs 

DV Death Valley 

E Elsinore 

FS *Fort Sage 

G *Garlock 

GR *Greenville 

GV *Green Valley and 

Concord 

H *Hayward

HA Hat Creek

HC *Hilton Creek & 

related 

HE Helendale

HL Honey Lake

HU Hunting Creek 

I *Imperial 

J *Johnson Valley & 

related 

KF *Kern Front & related

L Lenwood 

LA Los Alamos 

LL *Little Lake 

LO Los Osos 

LS Little Salmon 

M *Manix 

MA *Maacama 

MB Malibu 

MC McArthur 

ME Mesquite Lake 

MR Mad River 

N *Nunez 

ND Northern Death Valley 

NF North Frontal 

NI *Newport-Inglewood 

O Ortigalita 

OV *Owens Valley 

P Pleito & Wheeler 

Ridge 

PI *Pisgah-Bullion 

PM Pinto Mountain 

PV Panamint Valley 

R Raymond Hill 

RC Rose Canyon 

RH Rodgers CreekHealdsburg 

RM Red Mountain 

SA *San Andreas 

SC San Cayetano 

SF *San Fernando 

SG San Gregorio 

SGA San Gabriel 

SH *Superstition Hills 

SJ *San Jacinto

SN Sierra Nevada (zone)

SS San Simeon

SSR Simi-Santa Rosa

SV Surprise Valley

W Whittier

WM *White Mtns 

WW *White Wolf

V Ventura Figure 1. Principal active faults in California zoned under the Alquist-Priolo Earthquake Fault Zoning Act. Asterisk 

indicates faults with historic surface rupture. 
2007 FAULT-RUPTURE HAZARD ZONES IN CALIFORNIA 5

Fault Trace

A fault trace is the line formed by the intersection of a 

fault and the earth’s surface. It is the representation of a fault 

as depicted on a map, including maps of the Earthquake Fault 

Zones.

Active Fault

For the purposes of this Act, an active fault is defined by 

the State Mining and Geology Board as one which has “had 

surface displacement within Holocene time (about the last 

11,000 years)” (see Appendix B, Section 3601). This 

definition does not, of course, mean that faults lacking 

evidence for surface displacement within Holocene time are 

necessarily inactive. A fault may be presumed to be inactive 

based on satisfactory geologic evidence; however, the evidence 

necessary to prove inactivity sometimes is difficult to obtain 

and locally may not exist.

Potentially Active Fault

Because the Alquist-Priolo Act requires the State 

Geologist to establish Earthquake Fault Zones to encompass all 

“potentially and recently active” traces of the San Andreas, 

Calaveras, Hayward, and San Jacinto faults, additional 

definitions were needed (Section 2622). Initially, faults were 

defined as potentially active, and were zoned, if they showed 

evidence of surface displacement during Quaternary time (last 

1.6 million years, Figure 2). Exceptions were made for certain 

Quaternary (i.e., Pleistocene) faults that were presumed to be 

inactive based on direct geologic evidence of inactivity during 

all of Holocene time or longer. The term “recently active” was 

not defined, as it was considered to be covered by the term 

“potentially active.” Beginning in 1977, evidence of 

Quaternary surface displacement was no longer used as a 

criterion for zoning. However, the term “potentially active” 

continued to be used as a descriptive term on map explanations 

on EFZ maps until 1988.

Sufficiently Active and Well-defined

A major objective of the CGS’s continuing Fault 

Evaluation and Zoning Program is to evaluate the hundreds of 

remaining potentially active faults in California for zoning 

consideration. However, it became apparent as the program 

progressed that there are so many potentially 

active (i.e., Quaternary) faults in the state (Jennings, 1975) 

that it would be meaningless to zone all of them. In late 1975, 

the State Geologist made a policy decision to zone only those 

potentially active faults that have a relatively high potential for 

ground rupture. To facilitate this, the terms “sufficiently 

active” and “well-defined,” from Section 2622 of the Act, were 

defined for application in zoning faults other than the four 

named in the Act. These two terms constitute the present 

criteria used by the State Geologist in determining if a given 

fault should be zoned under the Alquist-Priolo Act.

Sufficiently active. A fault is deemed sufficiently active if 

there is evidence of Holocene surface displacement along one 

or more of its segments or branches. Holocene surface 

displacement may be directly observable or inferred; it need 

not be present everywhere along a fault to qualify that fault for 

zoning.

Well-defined. A fault is considered well-defined if its 

trace is clearly detectable by a trained geologist as a physical 

feature at or just below the ground surface. The fault may be 

identified by direct observation or by indirect methods (e.g., 

geomorphic evidence; Appendix C). The critical consideration 

is that the fault, or some part of it, can be located in the field 

with sufficient precision and confidence to indicate that the 

required site-specific investigations would meet with some 

success.

Determining if a fault is sufficiently active and welldefined is a matter of judgment. However, these definitions 

provide standard, workable guidelines for establishing 

Earthquake Fault Zones under the Act.

The evaluation of faults for zoning purposes is done with 

the realization that not all active faults can be identified. 

Furthermore, certain faults considered to be active at depth, 

because of known seismic activity, are so poorly defined at the 

surface that zoning is impractical. Although the map 

explanation indicates that “potentially active” (i.e., Quaternary) 

faults are identified and zoned (with exceptions) on the Official 

Maps of Earthquake Fault Zones until 1988, this is basically 

true only for those maps issued July 1, 1974 and January 1, 

1976. Even so, all of the principal faults zoned in 1974 and 

1976 were active during Holocene time, if not historically. 

Beginning with the maps of January 1, 1977, all faults zoned 

meet the criteria of “sufficiently active and well-defined.”
6 CALIFORNIA GEOLOGICAL SURVEY SP42

Delineating the Earthquake Fault Zones

Earthquake Fault Zones are delineated on U.S. Geological 

Survey topographic base maps at a scale of 1:24,000 (1 inch 

equals 2,000 feet). The zone boundaries are straight-line 

segments defined by turning points (Figure 3). Most of the 

turning points are intended to coincide with locatable features 

on the ground (e.g., bench marks, roads, streams). Neither the 

turning points nor the connecting zone boundaries have been 

surveyed to verify their mapped locations. 

Locations of Earthquake Fault Zone boundaries are 

controlled by the position of fault traces shown on the Official 

Maps of Earthquake Fault Zones. With few exceptions, the 

faults shown on the 1974 and 1976 Earthquake Fault Zones 

maps were not field-checked during the compilation of these 

maps. However, nearly all faults zoned since January 1, 1977 

have been evaluated in the field or on aerial photographs to 

verify that they do meet the criteria of being sufficiently active 

and well-defined.

Zone boundaries on early maps were positioned about 660 

feet (200 meters) away from the fault traces to accommodate 

imprecise locations of the faults and possible existence of 

active branches. The policy since 1977 is to position the EFZ 

boundary about 500 feet (150 meters) away from major active 

faults and about 200 to 300 feet (60 to 90 meters) away from 

well-defined, minor faults. Exceptions to this policy exist 

where faults are locally complex or where faults are not 

vertical.

Fault Evaluation and Zoning Program

The Fault Evaluation and Zoning Program was initiated in 

early 1976 for the purpose of evaluating those “other faults” 

identified in the Act as “sufficiently active and well-defined” 

(see definition above) after it was recognized that effective 

future zoning could not rely solely on the limited fault data of 

others. Justification of this program is discussed in more detail 

in Special Publication 47 of the Division of Mines and 

Geology (1976; also see Hart, 1978).

The program was originally scheduled over a 10-year 

period. The state was divided into 10 regions or work areas 

(Figure 1), with one region scheduled for evaluation each year. 

However, the work in some regions was extended due to heavy 

workloads. Fault evaluation work includes interpretation of 

aerial photographs and limited field mapping, as well as the 

use of other geologists’ work. A list of faults to be evaluated 

in a target region was prepared and priorities assigned. The list 

included potentially active faults not yet zoned, as well as 

previously zoned faults or fault-segments that warranted zone 

revisions (change or deletion). Faults also were evaluated in 

areas outside of scheduled regions, as the need arose (e.g., to 

map fault rupture immediately after an earthquake). The fault 

evaluation work was completed in early 1991. The work is 

summarized for each region in Open-File Reports (OFR) 77-8, 

78-10, 79-10, 81-3, 83-10, 84-52, 86-3, 88-1, 89-16, and 91-9 

(see Appendix E). Appendix E is a complete list of 

publications and products of the Fault Evaluation and Zoning 

Program.

For each fault evaluated, a Fault Evaluation Report (FER) 

was prepared, summarizing data on the location, recency of 

activity, and sense and magnitude of displacement. Each FER 

contains recommendations for or against zoning. These inhouse reports are filed at the CGS Sacramento Regional Office 

at 801 K Street, MS 12-31, Sacramento, 95814, where they are 

available for reference. Reference copies of the FERs are filed 

in the CGS’s Los Angeles and San Francisco Bay regional 

offices. An index to FERs prepared 1976 to April 1989 is 

available as OFR 90-9 (see Appendix E). This list and an 

index map identify the faults that have been evaluated. Digital 

files of all FER’s are available in pdf format (CGS CD 2002-

01; CD 2002-02; CD 2002-03) (see Appendix E). 

Under the AP Act (Sec. 2622), the State Geologist has an 

on-going responsibility to review “new geologic and seismic 

data” in order to revise the Earthquake Fault Zones and to 

delineate new zones “when warranted by new information.”

As a result of the fault evaluations made since 1976, 295

new and 155 revised Earthquake Fault Zones Maps have been 

issued and four maps have been withdrawn (Table 3). The 

faults zoned since 1976 are considered to meet the criteria of 

“sufficiently active and well-defined” (see Definitions above). 

Many other faults did not appear to meet the criteria and were 

not zoned. It is important to note that it is sometimes difficult 

to distinguish between slightly active faults and inactive ones, 

because the surface features formed as a result of minor, 

infrequent rupture are easily obliterated by geologic processes 

(erosion, sedimentation, mass wasting) or people’s activities. 

Even large scale fault-rupture can be obscured in complex 

geologic terranes or high-energy environments. Recent faultrupture also is difficult to detect where it is distributed as 

numerous breaks or warps in broad zones of deformation. As a 

consequence of these problems, it is not possible to identify 

and zone all active faults in California. For the most part, 

rupture on faults not identified as active is expected to be 

minor.

Since zones were first established in 1974, there have been 

25 earthquakes or earthquake sequences associated with 

surface faulting in various parts of California (Table 5). This 

is an average of 0.75 fault-rupture events per year. Most of the 

recent surface faulting has been relatively minor; either in 

terms of amount of displacement or length of surface rupture 

(Table 5). However, one foot (30 cm) or more displacement 

occurred during seven events. Earlier records (incomplete) 

suggest that displacements of 3 feet (one meter) or more occur 

at least once every 15 to 20 years in California (Bonilla, 1970; 

Grantz and Bartow, 1977). Many of the recent coseismic 

events occurred on faults that were not yet zoned, and a few 

were on faults not considered to be potentially active or not 

even mapped. However, coseismic rupture also occurred on 

faults mostly or entirely within the Earthquake Fault Zones in 

nine of the rupture events (Table 5). A sequence of four 

rupture events occurred in the Lompoc diatomite quarry and 

presumably was triggered by quarrying (see event #10, Table 

5). In addition, aseismic fault creep has occurred on many 

zoned faults in the last 30 years (see footnote, Table 5). Most 

fault creep is tectonically induced, although some is induced 

by people (mainly by fluid withdrawal).
2007 FAULT-RUPTURE HAZARD ZONES IN CALIFORNIA 7 
8 CALIFORNIA GEOLOGICAL SURVEY SP42
2007 FAULT-RUPTURE HAZARD ZONES IN CALIFORNIA 9 

In addition to evaluating and zoning faults, program 

staff also perform other functions necessary to the 

implementation of the APEFZ Act. Regulations (Section 

3603, Appendix B) require that cities and counties file 

geologic reports for “project” sites in Earthquake Fault 

Zones with the State Geologist. By the middle of 2006, 

over 4000 site-specific geologic reports investigating the 

hazard of surface-fault rupture had been filed for public 

reference. Site reports on file with CGS through 2000 

are available as digital images in pdf format (CGS CD 

2003-01; CD 2003-02). Reports filed after 2000 are 

available for reference at the Geologic Information and 

Publications Office in Sacramento (see Appendix E). 

In order to improve the quality of site investigations 

and reports, guidelines were prepared in 1975 to assist 

others in evaluating faults. These guidelines have been 

revised and appear as Appendix C.

General guidelines for reviewing geologic reports for 

adequacy, required by Section 3603 of the regulations, 

are provided in Appendix D.

If a city or county considers that a geologic 

investigation of a proposed “project” is unnecessary, it 

may request a waiver from the State Geologist (Section 

2623, Appendix A). A waiver form detailing the 

procedures used is provided in Appendix F. Through 

2006, 84 waiver requests have been processed by 

program staff.

Another important activity is to provide information 

on the APEFZ Act, the Division’s Fault Evaluation and 

Zoning Program, and fault-rupture hazards to both the 

public and private sectors. Program staff responds to 

about 1,500 inquiries each year from geologists, planners, 

building officials, developers, realtors, financial 

institutions, and others.

Uses and Limitations of Earthquake Fault Zones 

Maps

The Earthquake Fault Zones are delineated to define 

those areas within which fault-rupture hazard 

investigations are required prior to building structures for 

human occupancy. Traces of faults are shown on the 

maps mainly to justify the locations of zone boundaries. 

These fault traces are plotted as accurately as the sources 

of data permit; yet the plots are not sufficiently accurate 

to be used as the basis for building set-back requirements, 

and they should not be so used.

The fault information shown on the maps is not 

sufficient to meet the requirement for fault-rupture 

hazard investigations. Local governmental units must 

require developers to have project sites within the 

Earthquake Fault Zones evaluated to determine if a 

potential hazard from any fault, whether heretofore 

recognized or not, exists with regard to proposed 

structures and their occupants.

The surface fault-ruptures associated with historic 

earthquake and creep events are identified where known. 

However, no degree of relative potential for future 

surface displacement or degree of hazard is implied for 

the faults shown. Surface ruptures resulting from the 

secondary effects of seismic shaking (e.g., landsliding, 

differential settlement, liquefaction) are omitted from the 

map and do not serve as a basis for zoning.

Active faults may exist outside the Earthquake Fault 

Zones on any zone map. Therefore, fault investigations 

are recommended for all critical and important 

developments proposed outside the Earthquake Fault 

Zones.

INDEX TO MAPS OF EARTHQUAKE FAULT 

ZONES

The following pages (Figures 4A to 4J) indicate the 

names and locations of the Official Maps of Earthquake 

Fault Zones delineated by the California Geological 

Survey under the Alquist-Priolo Earthquake Fault Zoning 

Act (Appendix A). These index pages identify all 

Official Maps of Earthquake Fault Zones released by the 

State Geologist through August 2007. The official maps 

are compiled on U.S. Geological Survey 7.5-minute 

topographic quadrangle maps at a scale of 1 inch equals 

2,000 feet (Figure 3). Cities and counties affected by 

these maps are listed in Table 4.

Because Earthquake Fault Zones maps are issued 

every year or two to delineate revised and additional 

zones, users of these maps should check with the 

California Geological Survey for up-to-date information 

on new and revised Earthquake Fault Zones maps. A 

change in zones also may affect different local 

governments. This index to Official Maps of Earthquake 

Fault Zones (Figures 4A to 4J) will be revised in future 

years as new maps are issued.

The Earthquake Fault Zones maps are available for 

purchase as indicated under Availability of Earthquake 

Fault Zones Maps. Also, they may be consulted at any 

office of the California Geological Survey and at the 

planning departments of all cities and counties affected 

locally by Earthquake Fault Zones (Table 4).

Availability of Earthquake Fault Zones Maps 

Reproducible masters, from which copies of local 

Earthquake Fault Zones maps (scale 1:24,000) can be 

made, have been provided to each of the cities and 

counties affected by the zones. Requests for copies of
10 CALIFORNIA GEOLOGICAL SURVEY SP42

particular Earthquake Fault Zones maps of local areas 

should be directed to the Planning Director of the 

appropriate city or county. Refer to the index of 

Earthquake Fault Zones maps for the quadrangle names 

of the maps needed.

Arrangements also have been made with ARCBryant (formerly BPS Reprographic Services), San 

Francisco, to provide paper copies of the Earthquake 

Fault Zones maps to those who cannot get them 

conveniently from the cities and counties.

 ARC-Bryant

 945 Bryant Street

 San Francisco, CA 94103 

 Telephone: (415) 495-8700

Each map must be ordered by quadrangle name as 

shown on the index map. The cost of the maps is 

nominal; handling and C.O.D. charges are extra. These 

maps are not sold by the California Geological Survey. 

Digital files of the maps can be obtained from the 

California Geological Survey in both digital raster (pdf) 

and Geographic Information System (GIS) format. Refer 

to Appendix E for more information on obtaining digital 

files of the maps.

REFERENCES

(See Appendix E for Complete List of AP Products)

Bonilla, M.G., 1970, Surface faulting and related effects, 

in Wiegel, R.L, editor, Earthquake Engineering: 

Prentice-Hall, Inc., Englewood Cliffs, New Jersey, p. 

47-74.

California Division of Mines and Geology, 1976, Active 

fault mapping and evaluation program -- 10-year 

program to implement Alquist-Priolo Special Studies 

Zones Act: California Division of Mines and 

Geology Special Publication 47, 42 p.

Grantz, A. and Bartow, A., 1977, Active faults of 

California: U.S. Geological Survey pamphlet, 15 p.

Hart, E.W., 1978, Zoning for the hazard of surface fault 

rupture in California: International Conference on 

Microzonation, 2nd, San Francisco, 1978, 

Proceedings, v. 2, p. 635-646.

Hart, E.W., 1986, Zoning for the hazard of surface 

faulting in California, in Proceedings Conference 

XXXII -- Workshop on future directions in 

evaluating earthquake hazards in southern 

California, November 12-13, 1985: U.S. Geological 

Survey Open-File Report 86-401, p. 74-83.

Jennings, C.W., 1975, Fault map of California with 

locations of volcanoes, thermal springs, and thermal 

wells: California Division of Mines and Geology 

Data Map No. 1, scale 1:750,000.

Jennings, C.W., 1985, An explanatory text to accompany 

the 1:750,000 scale Fault and Geologic Maps of 

California: Division of Mines and Geology Bulletin 

201, 197 p., 2 plates.

Jennings, C.W., 1994, Fault activity map of California 

and adjacent areas: California Department of 

Conservation, Division of Mines and Geology 

Geologic Data Map No. 6, scale 1:750,000 

(appendices).

Reitherman, R. and Leeds, D.J., 1990, A study of the 

effectiveness of the Alquist-Priolo program: 

California Division of Mines and Geology Open-File 

Report 90-18, 131 p.
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22 CALIFORNIA GEOLOGICAL SURVEY SP 42 

APPENDICES 

 Data are presented herein to provide city and county officials, property owners, developers, geologists, and others 

with specific information they may need to effectuate the Act. 

 Because the Act must be implemented at the local government level, it is imperative that the local entities 

understand its various aspects. 

Appendix A 

ALQUIST-PRIOLO EARTHQUAKE FAULT ZONING ACT1

Excerpts from California Public Resources Code 

DIVISION 2. Geology, Mines and Mining 

CHAPTER 7.5 Earthquake Fault Zones2

2621. This chapter shall be known and may be cited as 

the Alquist-Priolo Earthquake Fault Zoning Act1. 

2621.5. (a) It is the purpose of this chapter to provide for 

the adoption and administration of zoning laws, ordinances, 

rules, and regulations by cities and counties in implementation 

of the general plan that is in effect in any city or county. The 

Legislature declares that this chapter is intended to provide 

policies and criteria to assist cities, counties, and state 

agencies in the exercise of their responsibility to prohibit the 

location of developments and structures for human occupancy 

across the trace of active faults. Further, it is the intent of this 

chapter to provide the citizens of the state with increased 

safety and to minimize the loss of life during and immediately 

following earthquakes by facilitating seismic retrofitting to 

strengthen buildings, including historical buildings, against 

ground shaking. 

 (b) This chapter is applicable to any project, as defined in 

Section 2621.6, which is located within a delineated 

earthquake fault zone, upon issuance of the official earthquake 

fault zones maps to affected local jurisdictions, except as 

provided in Section 2621.7. 

 (c) The implementation of this chapter shall be pursuant 

to policies and criteria established and adopted by the Board3 

2621.6. (a) As used in this chapter, “project” means either 

of the following: 

1 Known as the Alquist-Priolo Special Studies Zones Act prior to January 

1, 1994. 

2 Know as Special Studies Zones prior to January 1, 1994. 

3 State Mining and Geology Board. 

 (1) Any subdivision of land which is subject to the 

Subdivision Map Act, (Division 2 (commencing with 

Section 66410) of Title 7 of the Government Code), 

and which contemplates the eventual construction of 

structures for human occupancy. 

 (2) Structures for human occupancy, with the exception of 

either of the following: 

 (A) Single-family wood-frame or steel-frame 

dwellings to be built on parcels of land for which 

geologic reports have been approved pursuant to 

paragraph (1). 

 (B) A single-family wood-frame or steel-frame 

dwelling not exceeding two stories when that dwelling 

is not part of a development of four or more dwellings. 

 (b) For the purposes of this chapter, a mobilehome whose 

body width exceeds eight feet shall be considered to be a 

single-family wood-frame dwelling not exceeding two stories. 

2621.7. This chapter, except Section 2621.9, shall not 

apply to any of the following: 

 (a) The conversion of an existing apartment complex into 

a condominium. 

 (b) Any development or structure in existence prior to 

May 4, 1975, except for an alteration or addition to a structure 

that exceeds the value limit specified in subdivision (c). 

(c) An alteration or addition to any structure if the value 

of the alteration or addition does not exceed 50 percent of the 

value of the structure. 

 (d) (1) Any structure located within the jurisdiction of the 

City of Berkeley or the City of Oakland which was 
2007 FAULT-RUPTURE HAZARD ZONES IN CALIFORNIA 23 

damaged by fire between October 20, 1991, and October 23, 

1991, if granted an exemption pursuant to this subdivision. 

 (2) The city may apply to the State Geologist for an 

exemption and the State Geologist shall grant the 

exemption only if the structure located within the 

earthquake fault zone is not situated upon a trace of an 

active fault line, as delineated in an official earthquake 

fault zone map or in more recent geologic data, as 

determined by the State Geologist. 

 (3) When requesting an exemption, the city shall submit 

to the State Geologist all of the following information: 

(A) Maps noting the parcel numbers of proposed 

building sites that are at least 50 feet from an 

identified fault and a statement that there is not any 

more recent information to indicate a geologic hazard. 

 (B) Identification of any sites within 50 feet of an 

identified fault. 

 (C) Proof that the property owner has been notified 

that the granting of an exemption is not any guarantee 

that a geologic hazard does not exist. 

 (4) The granting of an exemption does not relieve a seller 

of real property or an agent for the seller of the 

obligation to disclose to a prospective purchaser that 

the property is located within a delineated earthquake 

fault zone, as required by Section 2621.9. 

 (e) (1) Alterations which include seismic retrofitting, as 

defined in Section 8894.2 of the Government Code, to any of 

the following listed types of buildings in existence prior to 

May 4, 1975: 

 (A) Unreinforced masonry buildings, as described in 

subdivision (a) of Section 8875 of the Government 

Code. 

 (B) Concrete tilt-up buildings, as described in Section 

8893 of the Government Code. 

 (C) Reinforced concrete moment resisting frame 

buildings as described in Applied Technology Council 

Report 21 (FEMA Report 154). 

 (2) The exemption granted by paragraph (1) shall not 

apply unless a city or county acts in accordance with 

all of the following: 

 (A) The building permit issued by the city or county 

for the alterations authorizes no greater human 

occupancy load, regardless of proposed use, than that 

authorized for the existing use permitted at the time the 

city or county grants the exemption. This may be 

accomplished by the city or county making a human 

occupancy load determination that is based on, and no 

greater than, the existing authorized use, and including 

that determination on the building permit application 

as well as a statement substantially as follows: “Under 

subparagraph (A) of paragraph (2) of subdivision (e) of 

Section 2621.7 of the Public Resources Code, the 

occupancy load is limited to the occupancy load for the 

last lawful use authorized or existing prior to the 

issuance of this building permit, as determined by the 

city or county.”

 (B) The city or county requires seismic retrofitting, as 

defined in Section 8894.2 of the Government Code, 

which is necessary to strengthen the entire structure 

and provide increased resistance to ground shaking 

from earthquakes. 

 (C) Exemptions granted pursuant to paragraph (1) are 

reported in writing to the State Geologist within 30 

days of the building permit issuance date. 

 (3) Any structure with human occupancy restrictions 

under subparagraph (A) of paragraph (2) shall not be 

granted a new building permit that allows an increase 

in human occupancy unless a geologic report, prepared 

pursuant to subdivision (d) of Section 3603 of Title 14 

of the California Code of Regulations in effect on 

January 1, 1994, demonstrates that the structure is not 

on the trace of an active fault, or the requirement of a 

geologic report has been waived pursuant to Section 

2623.

 (4) A qualified historical building within an earthquake 

fault zone that is exempt pursuant to this subdivision 

may be repaired or seismically retrofitted using the 

State Historical Building Code, except that, 

notwithstanding any provision of that building code 

and its implementing regulations, paragraph (2) shall 

apply. 

2621.8. Notwithstanding Section 818.2 of the 

Government Code, a city or county which knowingly issues a 

permit that grants an exemption pursuant to subdivision (e) of 

Section 2621.7 that does not adhere to the requirements of 

paragraph (2) of subdivision (e) of Section 2621.7, may be 

liable for earthquake-related injuries or deaths caused by 

failure to so adhere. 

2621.9. (a) A person who is acting as an agent for a 

transferor of real property that is located within a delineated 

earthquake fault zone, or the transferor, if he or she is acting 

without an agent, shall disclose to any prospective transferee 

the fact that the property is located within a delineated 

earthquake fault zone. 
24 CALIFORNIA GEOLOGICAL SURVEY SP 42 

 (b) Disclosure is required pursuant to this section only 

when one of the following conditions is met: 

(1) The transferor, or the transferor's agent, has actual 

knowledge that the property is within a delineated 

earthquake fault zone. 

(2) A map that includes the property has been provided 

to the city or county pursuant to Section 2622, and a 

notice has been posted at the offices of the county 

recorder, county assessor, and county planning 

agency that identifies the location of the map and 

any information regarding changes to the map 

received by the county. 

 (c) In all transactions that are subject to Section 1103 of 

the Civil Code, the disclosure required by subdivision (a) of 

this section shall be provided by either of the following means: 

(1) The Local Option Real Estate Transfer Disclosure 

Statement as provided in Section 1102.6a of the 

Civil Code. 

(2) The Natural Hazard Disclosure Statement as 

provided in Section 1103.2 of the Civil Code. 

 (d) If the map or accompanying information is not of 

sufficient accuracy or scale that a reasonable person can 

determine if the subject real property is included in a 

delineated earthquake fault hazard zone, the agent shall mark 

"Yes" on the Natural Hazard Disclosure Statement. The agent 

may mark "No" on the Natural Hazard Disclosure Statement if 

he or she attaches a report prepared pursuant to subdivision (c) 

of Section 1103.4 of the Civil Code that verifies the property 

is not in the hazard zone. Nothing in this subdivision is 

intended to limit or abridge any existing duty of the transferor 

or the transferor's agents to exercise reasonable care in making 

a determination under this subdivision. 

 (e) For purposes of the disclosures required by this 

section, the following persons shall not be deemed agents of 

the transferor: 

(1) Persons specified in Section 1103.11 of the Civil 

Code. 

(2) Persons acting under a power of sale regulated by 

Section 2924 of the Civil Code. 

 (f) For purposes of this section, Section 1103.13 of the 

Civil Code shall apply. 

 (g) The specification of items for disclosure in this section 

does not limit or abridge any obligation for disclosure created 

by any other provision of law or that may exist in order to 

avoid fraud, misrepresentation, or deceit in the transfer 

transaction. 

2622. (a) In order to assist cities and counties in their 

planning, zoning, and building-regulation functions, the State 

Geologist shall delineate, by December 31, 1973, appropriately 

wide earthquake fault zones to encompass all potentially and 

recently active traces of the San Andreas, Calaveras, Hayward, 

and San Jacinto Faults, and such other faults, or segments 

thereof, as the State Geologist determines to be sufficiently 

active and well-defined as to constitute a potential hazard to 

structures from surface faulting or fault creep. The earthquake 

fault zones shall ordinarily be one-quarter mile or less in 

width, except in circumstances which may require the State 

Geologist to designate a wider zone. 

 (b) Pursuant to this section, the State Geologist shall 

compile maps delineating the earthquake fault zones and shall 

submit the maps to all affected cities, counties, and state 

agencies, not later than December 31, 1973, for review and 

comment. Concerned jurisdictions and agencies shall submit 

all comments to the State Mining and Geology Board for 

review and consideration within 90 days. Within 90 days of 

such review, the State Geologist shall provide copies of the 

official maps to concerned state agencies and to each city or 

county having jurisdiction over lands lying within any such 

zone. 

 (c) The State Geologist shall continually review new 

geologic and seismic data and shall revise the earthquake fault 

zones or delineate additional earthquake fault zones when 

warranted by new information. The State Geologist shall 

submit all revised maps and additional maps to all affected 

cities, counties, and state agencies for their review and 

comment. Concerned jurisdictions and agencies shall submit 

all comments to the State Mining and Geology Board for 

review and consideration within 90 days. Within 90 days of 

that review, the State Geologist shall provide copies of the 

revised and additional official maps to concerned state 

agencies and to each city or county having jurisdiction over 

lands lying within the earthquake fault zone. 

 (d) In order to ensure that sellers of real property and 

their agents are adequately informed, any county that receives 

an official map pursuant to this section shall post a notice 

within five days of receipt of the map at the offices of the 

county recorder, county assessor, and county planning 

commission, identifying the location of the map and the 

effective date of the notice. 

2623. (a) The approval of a project by a city or 

county shall be in accordance with policies and criteria 

established by the State Mining and Geology Board and the 

findings of the State Geologist. In the development of such 

policies and criteria, the State Mining and Geology Board 

shall seek the comment and advice of affected cities, counties, 
2007 FAULT-RUPTURE HAZARD ZONES IN CALIFORNIA 25

and state agencies. Cities and counties shall require, prior to 

the approval of a project, a geologic report defining and 

delineating any hazard of surface fault rupture. If the city or 

county finds that no undue hazard of that kind exists, the 

geologic report on the hazard may be waived, with the approval 

of the State Geologist. 

 (b) After a report has been approved or a waiver granted, 

subsequent geologic reports shall not be required, provided 

that new geologic data warranting further investigations is not 

recorded. 

 (c) The preparation of geologic reports that are required 

pursuant to this section for multiple projects may be 

undertaken by a geologic hazard abatement district. 

2624. Notwithstanding any provision of this chapter, 

cities and counties may do any of the following: 

 (1) Establish policies and criteria which are stricter than 

those established by this chapter. 

 (2) Impose and collect fees in addition to those required 

under this chapter. 

 (3) Determine not to grant exemptions authorized under 

this chapter. 

2625. (a) Each applicant for approval of a project may be 

charged a reasonable fee by the city or county having 

jurisdiction over the project. 

 (b) Such fees shall be set in an amount sufficient to meet, 

but not to exceed, the costs to the city or county of 

administering and complying with the provisions of this 

chapter. 

 (c) The geologic report required by Section 2623 shall be 

in sufficient detail to meet the criteria and policies established 

by the State Mining and Geology Board for individual parcels 

of land. 

2630. In carrying out the provisions of this chapter, the 

State Geologist and the board shall be advised by the Seismic 

Safety Commission. 

SIGNED INTO LAW DECEMBER 22, 1972; AMENDED SEPTEMBER 16, 1974, MAY 4, 1975, SEPTEMBER 28, 1975, 

SEPTEMBER 22, 1976, SEPTEMBER 27, 1979, SEPTEMBER 21, 1990, JULY 29, 1991, AUGUST 16, 1992, JULY 25, 

1993, OCTOBER 7, 1993, AND OCTOBER 7, 1997
26 CALIFORNIA GEOLOGICAL SURVEY SP 42 

Appendix B 

POLICIES AND CRITERIA OF THE STATE MINING AND GEOLOGY BOARD 

With Reference to the Alquist-Priolo Earthquake Fault Zoning Act 

(Excerpts from the California Code of Regulations, Title 14, Division 2) 

3600. Purpose. 

 It is the purpose of this subchapter to set forth the 

policies and criteria of the State Mining and Geology 

Board, hereinafter referred to as the “Board,” governing 

the exercise of city, county, and state agency 

responsibilities to prohibit the location of developments 

and structures for human occupancy across the trace of 

active faults in accordance with the provisions of Public 

Resources Code Section 2621 et seq. (Alquist-Priolo 

Earthquake Fault Zoning Act). The policies and criteria 

set forth herein shall be limited to potential hazards 

resulting from surface faulting or fault creep within 

earthquake fault zones delineated on maps officially 

issued by the State Geologist. 

NOTE: Authority cited: Section 2621.5, Public 

Resources Code. Reference: Sections 2621-2630, Public 

Resources Code. 

3601. Definitions. 

 The following definitions as used within the Act and 

herein shall apply: 

(a) An “active fault” is a fault that has had surface 

displacement within Holocene time (about the last 11,000 

years), hence constituting a potential hazard to structures 

that might be located across it.

(b) A “fault trace” is that line formed by the 

intersection of a fault and the earth’s surface, and is the 

representation of a fault as depicted on a map, including 

maps of earthquake fault zones. 

(c) A “lead agency” is the city or county with the 

authority to approve projects. 

(d) “Earthquake fault zones” are areas delineated by 

the State Geologist, pursuant to the Alquist-Priolo 

Earthquake Fault Zoning Act (Public Resources Code 

Section 2621 et seq.) and this subchapter, which 

encompass the traces of active faults. 

(e) A “structure for human occupancy” is any 

structure used or intended for supporting or sheltering any 

use or occupancy, which is expected to have a human 

occupancy rate of more than 2,000 person-hours per year. 

(f) “Story” is that portion of a building included 

between the upper surface of any floor and the upper 

surface of the floor next above, except that the topmost 

story shall be that portion of a building included between 

the upper surface of the topmost floor and the ceiling or 

roof above. For the purpose of the Act and this 

subchapter, the number of stories in a building is equal to 

the number of distinct floor levels, provided that any 

levels that differ from each other by less than two feet 

shall be considered as one distinct level. 

NOTE: Authority cited: Section 2621.5, Public 

Resources Code. Reference: Sections 2621-2630, Public 

Resources Code. 

3602. Review of Preliminary Maps. 

 (a) Within 45 days from the issuance of proposed 

new or revised preliminary earthquake fault zone map(s), 

cities and counties shall give notice of the Board’s 

announcement of a ninety (90) day public comment period 

to property owners within the area of the proposed zone. 

The notice shall be by publication, or other means 

reasonably calculated to reach as many of the affected 

property owners as feasible. Cities and counties may also 

give notice to consultants who may conduct geologic 

studies in fault zones. The notice shall state that its 

purpose is to provide an opportunity for public comment 

including providing to the Board geologic information that 

may have a bearing on the proposed map(s). 

 (b) The Board shall also give notice by mail to those 

California Registered Geologists and California 

Registered Geophysicists on a list provided by the State 

Board of Registration for Geologists and Geophysicists. 

The notice shall indicate the affected jurisdictions and 

state that its purpose is to provide an opportunity to 

present written technical comments that may have a 

bearing on the proposed zone map(s) to the Board during 

a 90-day public comment period. 

 (c) The Board shall receive public comments during 

the 90-day public comment period. The Board shall 
2007 FAULT-RUPTURE HAZARD ZONES IN CALIFORNIA 27

conduct at least one public hearing on the proposed zone 

map(s) during the 90-day public comment period. 

 (d) Following the end of the 90-day public comment 

period, the Board shall forward its comments and 

recommendations with supporting data received to the 

State Geologist for consideration prior to the release of 

official earthquake fault zone map(s). 

NOTE: Authority cited: Section 2621.5, Public 

Resources Code. Reference: Section 2622, Public 

Resources Code. 

3603. Specific Criteria. 

 The following specific criteria shall apply within 

earthquake fault zones and shall be used by affected lead 

agencies in complying with the provisions of the Act: 

 (a) No structure for human occupancy, identified as a 

project under Section 2621.6 of the Act, shall be 

permitted to be placed across the trace of an active fault. 

Furthermore, as the area within fifty (50) feet of such 

active faults shall be presumed to be underlain by active 

branches of that fault unless proven otherwise by an 

appropriate geologic investigation and report prepared as 

specified in Section 3603(d) of this subchapter, no such 

structures shall be permitted in this area. 

 (b) Affected lead agencies, upon receipt of official 

earthquake fault zones maps, shall provide for disclosure 

of delineated earthquake fault zones to the public. Such 

disclosure may be by reference in general plans, specific 

plans, property maps, or other appropriate local maps. 

 (c) No change in use or character of occupancy, 

which results in the conversion of a building or structure 

from one not used for human occupancy to one that is so 

used, shall be permitted unless the building or structure 

complies with the provisions of the Act. 

 (d) Application for a development permit for any 

project within a delineated earthquake fault zone shall be 

accompanied by a geologic report prepared by a geologist 

registered in the State of California, which is directed to 

the problem of potential surface fault displacement 

through the project site, unless such report is waived 

pursuant to Section 2623 of the Act. The required report 

shall be based on a geologic investigation designed to 

identify the location, recency, and nature of faulting that 

may have affected the project site in the past and may 

affect the project site in the future. The report may be 

combined with other geological or geotechnical reports. 

 (e) A geologist registered in the State of California, 

within or retained by each lead agency, shall evaluate the 

geologic reports required herein and advise the lead 

agency. 

 (f) One (1) copy of all such geologic reports shall be 

filed with the State Geologist by the lead agency within 

thirty (30) days following the report’s acceptance. The 

State Geologist shall place such reports on open file. 

NOTE: Authority cited: Section 2621.5, Public 

Resources Code. Reference: Sections 2621.5, 2622, 

2623, and 2625(c), Public Resources Code. 

ADOPTED NOVEMBER 23, 1973; REVISED JULY 1, 1974, AND JUNE 26, 1975. 

CODIFIED IN CALIFORNIA CODE OF REGULATIONS JANUARY 31, 1979; 

REVISED OCTOBER 18, 1984, JANUARY 5, 1996, AND APRIL 1, 1997. 
28 CALIFORNIA GEOLOGICAL SURVEY SP 42 

Appendix C 

GUIDELINES FOR EVALUATING THE HAZARD 

OF SURFACE RUPTURE 

(These guidelines, also published as DMG Note 49 (1997), are not part of the Policies and Criteria of the State 

Mining and Geology Board. Similar guidelines were adopted by the Board for advisory purposes in 1996.) 

These guidelines are to assist geologists who investigate 

faults relative to the hazard of surface fault rupture. 

Subsequent to the passage of the Alquist-Priolo Earthquake 

Fault Zoning Act (1972), it became apparent that many fault 

investigations conducted in California were incomplete or 

otherwise inadequate for the purpose of evaluating the 

potential of surface fault rupture. It was further apparent that 

statewide standards for investigating faults would be 

beneficial. These guidelines were initially prepared in 1975 

as DMG Note 49 and have been revised several times since 

then. 

 The investigation of sites for the possible hazard of 

surface fault rupture is a deceptively difficult geologic task. 

Many active faults are complex, consisting of multiple breaks. 

Yet the evidence for identifying active fault traces is generally 

subtle or obscure and the distinction between recently active 

and long-inactive faults may be difficult to make. It is 

impractical from an economic, engineering, and architectural 

point of view to design a structure to withstand serious 

damage under the stress of surface fault rupture. Once a 

structure is sited astride an active fault, the resulting faultrupture hazard cannot be mitigated unless the structure is 

relocated, whereas when a structure is placed on a landslide, 

the potential hazard from landsliding often can be mitigated. 

Most surface faulting is confined to a relatively narrow zone a 

few feet to a few tens of feet wide, making avoidance (i.e., 

building setbacks) the most appropriate mitigation method. 

However, in some cases primary fault rupture or rupture along 

branch faults can be distributed across zones hundreds of feet 

wide or manifested as broad warps, suggesting that 

engineering strengthening or design may be of additional 

mitigative value (e.g., Lazarte and others, 1994). 

 No single investigative method will be the best, or even 

useful, at all sites, because of the complexity of evaluating 

surface and near surface faults and because of the infinite 

variety of site conditions. Nonetheless, certain investigative 

methods are more helpful than others in locating faults and 

evaluating the recency of activity. 

 The evaluation of a given site with regard to the potential 

hazard of surface fault rupture is based extensively on the 

concepts of recency and recurrence of faulting along existing 

faults. In a general way, the more recent the faulting the 

greater the probability for future faulting (Allen, 1975). 

Stated another way, faults of known historic activity during 

the last 200 years, as a class, have a greater probability for 

future activity than faults classified as Holocene age (last 

11,000 years) and a much greater probability of future activity 

than faults classified as Quaternary age (last 1.6 million 

years). However, it should be kept in mind that certain faults 

have recurrent activity measured in tens or hundreds of years 

whereas other faults may be inactive for thousands of years 

before being reactivated. Other faults may be characterized 

by creep-type rupture that is more or less on-going. The 

magnitude, sense, and nature of fault rupture also vary for 

different faults or even along different strands of the same 

fault. Even so, future faulting generally is expected to recur 

along pre-existing faults (Bonilla, 1970, p. 68). The 

development of a new fault or reactivation of a long-inactive 

fault is relatively uncommon and generally need not be a 

concern in site development. 

 As a practical matter, fault investigations should be 

directed at the problem of locating existing faults and then 

attempting to evaluate the recency of their activity. Data 

should be obtained both from the site and outside the site 

area. The most useful and direct method of evaluating 

recency is to observe (in a trench or road cut) the youngest 

geologic unit faulted and the oldest unit that is not faulted. 

Even so, active faults may be subtle or discontinuous and 

consequently overlooked in trench exposures (Bonilla and 

Lienkaemper, 1991). Therefore, careful logging is essential 

and trenching needs to be conducted in conjunction with 

other methods. For example, recently active faults may also 

be identified by direct observation of young, fault-related 

geomorphic (i.e., topographic) features in the field or on 

aerial photographs. Other indirect and more interpretive 

methods are identified in the outline below. Some of these 

methods are discussed in Bonilla (1982), Carver and 

McCalpin (1996), Hatheway and Leighton (1979), McCalpin 
2007 FAULT-RUPTURE HAZARD ZONES IN CALIFORNIA 29

(1996a, b, c), National Research Council (1986), Sherard and 

others (1974), Slemmons (1977), Slemmons and dePolo 

(1986), Taylor and Cluff (1973), the Utah Section of the 

Association of Engineering Geologists (1987), Wallace 

(1977), Weldon and others (1996), and Yeats and others 

(1997). McCalpin (1996b) contains a particularly useful 

discussion of various field techniques. Many other useful 

references are listed in the bibliographies of the references 

cited here. 

 The purpose, scope, and methods of investigation for 

fault investigations will vary depending on conditions at 

specific sites and the nature of the projects. Contents and 

scope of the investigation also may vary based on guidelines 

and review criteria of agencies or political organizations 

having regulatory responsibility. However, there are topics 

that should be considered in all comprehensive fault 

investigations and geologic reports on faults. For a given site 

some topics may be addressed in more detail than at other 

sites because of the difference in the geologic and/or tectonic 

setting and/or site conditions. These investigative 

considerations should apply to any comprehensive fault 

investigation and may be applied to any project site, large or 

small. Suggested topics, considerations, and guidelines for 

fault investigations and reports on faults are provided in the 

following annotated outline. Fault investigations may be 

conducted in conjunction with other geologic and 

geotechnical investigations (see DMG Notes 42 and 44; also 

California Department of Conservation, Division of Mines 

and Geology, 1997). Although not all investigative 

techniques need to be or can be employed in evaluating a 

given site, the outline provides a checklist for preparing 

complete and well-documented reports. Most reports on fault 

investigations are reviewed by local or state government 

agencies. Therefore it is necessary that the reports be 

documented adequately and written carefully to facilitate that 

review. The importance of the review process is emphasized 

here, because it is the reviewer who must evaluate the 

adequacy of reports, interpret or set standards where they are 

unclear, and advise the governing agency as to their 

acceptability (Hart and Williams, 1978; DMG Note 41). 

 The scope of the investigation is dependent not only on 

the complexity and economics of a project, but also on the 

level of risk acceptable for the proposed structure or 

development. A more detailed investigation should be made 

for hospitals, high-rise buildings, and other critical or 

sensitive structures than for low-occupancy structures such as 

wood-frame dwellings that are comparatively safe. The 

conclusions drawn from any given set of data, however, must 

be consistent and unbiased. Recommendations must be 

clearly separated from conclusions, because recommendations 

are not totally dependent on geologic factors. The final 

decision as to whether, or how, a given project should be 

developed lies in the hands of the owner and the governing 

body that must review and approve the project. 

CONTENTS OF GEOLOGIC REPORTS ON FAULTS 

Suggested topics, considerations, and guidelines for 

investigations and reports 

 The following topics should be considered and addressed 

in detail where essential to support opinions, conclusions, 

and recommendations, in any geologic report on faults. It is 

not expected that all of the topics or investigative methods 

would be necessary in a single investigation. In specific cases 

it may be necessary to extend some of the investigative 

methods well beyond the site or property being investigated. 

Particularly helpful references are cited parenthetically below.

I. Text. 

A. Purpose and scope of investigation; description of 

proposed development. 

B. Geologic and tectonic setting. Include seismicity 

and earthquake history. 

C. Site description and conditions, including dates of 

site visits and observations. Include information on 

geologic units, graded and filled areas, vegetation, 

existing structures, and other factors that may affect 

the choice of investigative methods and the 

interpretation of data. 

D. Methods of investigation. 

1. Review of published and unpublished literature, 

maps, and records concerning geologic units, 

faults, ground-water barriers, and other factors. 

2. Stereoscopic interpretation of aerial 

photographs and other remotely sensed images 

to detect fault-related topography (geomorphic 

features), vegetation and soil contrasts, and 

other lineaments of possible fault origin. The 

area interpreted usually should extend beyond 

the site boundaries. 

3. Surface observations, including mapping of 

geologic and soil units, geologic structures, 

geomorphic features and surfaces, springs, 

deformation of engineered structures due to 

fault creep, both on and beyond the site. 

4. Subsurface investigations. 
30 CALIFORNIA GEOLOGICAL SURVEY SP 42 

a. Trenching and other excavations to permit 

detailed and direct observation of 

continuously exposed geologic units, soils, 

and structures; must be of adequate depth 

and be carefully logged (see Taylor and 

Cluff, 1973; Hatheway and Leighton, 1979; 

McCalpin, 1996b). 

b. Borings and test pits to permit collection of 

data on geologic units and ground water at 

specific locations. Data points must be 

sufficient in number and spaced adequately 

to permit valid correlations and 

interpretations. 

c. Cone penetrometer testing (CPT) (Grant 

and others, 1997; Edelman and others, 

1996). CPT must be done in conjunction 

with continuously logged borings to 

correlate CPT results with on-site materials. 

The number of borings and spacing of CPT 

soundings should be sufficient to 

adequately image site stratigraphy. The 

existence and location of a fault based on 

CPT data are interpretative. 

5. Geophysical investigations. These are indirect 

methods that require a knowledge of specific 

geologic conditions for reliable interpretations. 

They should seldom, if ever, be employed alone 

without knowledge of the geology (Chase and 

Chapman, 1976). Geophysical methods alone 

never prove the absence of a fault nor do they 

identify the recency of activity. The types of 

equipment and techniques used should be 

described and supporting data presented 

(California Board of Registration for Geologists 

and Geophysicists, 1993). 

a. High resolution seismic reflection 

(Stephenson and others, 1995; McCalpin, 

1996b). 

b. Ground penetrating radar (Cai and others, 

1996). 

c. Other methods include: seismic refraction, 

magnetic profiling, electrical resistivity, and 

gravity (McCalpin, 1996b). 

6. Age-dating techniques are essential for 

determining the ages of geologic units, soils, 

and surfaces that bracket the time(s) of faulting 

(Pierce, 1986; Birkeland and others, 1991; 

Rutter and Catto, 1995; McCalpin, 1996a). 

a. Radiometric dating (especially 14C). 

b. Soil-profile development. 

c. Rock and mineral weathering. 

d. Landform development. 

e. Stratigraphic correlation of 

rocks/minerals/fossils. 

f. Other methods -- artifacts, historical 

records, tephrochronology, fault scarp 

modeling, thermoluminescence, 

lichenometery, paleomagnetism, 

dendrochronology, etc. 

7. Other methods should be included when special 

conditions permit or requirements for critical 

structures demand a more intensive 

investigation. 

a. Aerial reconnaissance overflights. 

b. Geodetic and strain measurements. 

c. Microseismicity monitoring. 

E. Conclusions. 

1. Location and existence (or absence) of 

hazardous faults on or adjacent to the site; ages 

of past rupture events. 

2. Type of faults and nature of anticipated offset, 

including sense and magnitude of displacement, 

if possible. 

3. Distribution of primary and secondary faulting 

(fault zone width) and fault-related deformation. 

4. Probability of or relative potential for future 

surface displacement. The likelihood of future 

ground rupture seldom can be stated 

mathematically, but may be stated in 

semiquantitative terms such as low, moderate, or 

high, or in terms of slip rates determined for 

specific fault segments. 

5. Degree of confidence in and limitations of data 

and conclusions. 
2007 FAULT-RUPTURE HAZARD ZONES IN CALIFORNIA 31

F. Recommendations. 

1. Setback distances of proposed structures from 

hazardous faults. The setback distance 

generally will depend on the quality of data and 

type and complexity of fault(s) encountered at 

the site. In order to establish an appropriate 

setback distance from a fault located by indirect 

or interpretative methods (e.g. borings or cone 

penetrometer testing), the area between data 

points also should be considered underlain by a 

fault unless additional data are used to more 

precisely locate the fault. State and local 

regulations may dictate minimum distances (e.g., 

Sec. 3603 of California Code of Regulations, 

Appendix B). 

2. Additional measures (e.g., strengthened 

foundations, engineering design, flexible utility 

connections) to accommodate warping and 

distributive deformation associated with faulting 

(Lazarte and others, 1994). 

3. Risk evaluation relative to the proposed 

development. 

4. Limitations of the investigation; need for 

additional studies. 

II. References. 

A. Literature and records cited or reviewed; citations 

should be complete. 

B. Aerial photographs or images interpreted -- list type, 

date, scale, source, and index numbers. 

C. Other sources of information, including well records, 

personal communications, and other data sources. 

III. Illustrations -- these are essential to the understanding of 

the report and to reduce the length of text. 

A. Location map -- identify site locality, significant 

faults, geographic features, regional geology, seismic 

epicenters, and other pertinent data; 1:24,000 scale 

is recommended. If the site investigation is done in 

compliance with the Alquist-Priolo Act, show site 

location on the appropriate Official Map of 

Earthquake Fault Zones. 

B. Site development map -- show site boundaries, 

existing and proposed structures, graded areas, 

streets, exploratory trenches, borings, geophysical 

traverses, locations of faults, and other data; 

recommended scale is 1:2,400 (1 inch equals 200 

feet), or larger. 

C. Geologic map -- show distribution of geologic units 

(if more than one), faults and other structures, 

geomorphic features, aerial photographic lineaments, 

and springs; on topographic map 1:24,000 scale or 

larger; can be combined with III(A) or III(B). 

D. Geologic cross-sections, if needed, to provide 3-

dimensional picture. 

E. Logs of exploratory trenches and borings -- show 

details of observed features and conditions; should 

not be generalized or diagrammatic. Trench logs 

should show topographic profile and geologic 

structure at a 1:1 horizontal to vertical scale; scale 

should be 1:60 (1 inch = 5 feet) or larger. 

F. Geophysical data and geologic interpretations. 

IV. Appendix: Supporting data not included above (e.g., 

water well data, photographs, aerial photographs). 

V. Authentication: Investigating geologist’s signature and 

registration number with expiration date. 

REFERENCES 

Allen, C.R., 1975, Geologic criteria for evaluating seismicity: 

Geological Society of America Bulletin, v. 86, p. 1041-

1056. 

Birkeland, P.W., Machette, M.N., and Haller, K.M., 1991, 

Soils as a tool for applied Quaternary geology: Utah 

Geological and Mineral Survey Miscellaneous 

Publication 91-3, 63 p. 

Bonilla, M.G., 1970, Surface faulting and related effects, in

Wiegel, R.L., editor, Earthquake Engineering, PrenticeHall, Inc., Englewood Cliffs, New Jersey, p. 47-74.

Bonilla, M.G., 1982, Evaluation of potential surface faulting 

and other tectonic deformation: U.S. Geological Survey 

Open-File Report 82-732, 58 p. 

Bonilla, M.G., and Lienkaemper, J.J., 1991, Factors affecting 

the recognition of faults in exploratory trenches: U.S. 

Geological Survey Bulletin 1947, 54 p. 

Cai, J., McMecham, G.A., and Fisher, M.A., 1996, 

Application of ground-penetrating radar to investigation 
32 CALIFORNIA GEOLOGICAL SURVEY SP 42 

of near-surface fault properties in the San Francisco bay 

region: Bulletin of the Seismological Society of America, 

v. 86, p. 1459-1470. 

California Department of Conservation, Division of Mines 

and Geology DMG Notes: 

 DMG NOTE 41 - General guidelines for reviewing 

geologic reports, 1997. 

 DMG NOTE 42 - Guidelines to geologic/seismic 

reports, 1986. 

 DMG NOTE 44 - Recommended guidelines for 

preparing engineering geologic reports, 1986. 

 DMG NOTE 49 - Guidelines for evaluating the hazard 

of surface fault rupture, 1997. 

California Department of Conservation, Division of Mines 

and Geology, 1997, Guidelines for evaluating and 

mitigating seismic hazards in California: Special 

Publication 117, 74 p. 

California State Board of Registration for Geologists and 

Geophysicists, 1993, Guidelines for geophysical reports, 

5 p. 

Carver, G.A., and McCalpin, J.P., 1996, Paleoseismology of 

compressional tectonic environments, in McCalpin, J.P., 

editor, Paleoseismology: Academic Press, p. 183-270.

Chase, G.W. and Chapman, R.H., 1976, Black-box geology --

uses and misuses of geophysics in engineering geology: 

California Geology, v. 29, p 8-12. 

Edelman, S.H., and Holguin, A.R., 1996 (in press), Cone 

Penetrometer Testing for characterization and sampling 

of soil and groundwater, in Morgan, J.H, editor, 

Sampling Environmental Media ASTM STP 1282: 

American Society for Testing Materials, Philadelphia, 

Pennsylvania. 

Grant, L.B., Waggoner, J.T., Rockwell, T.K., and von Stein, 

C., 1997, Paleoseismicity of the North Branch of the 

Newport-Inglewood fault zone in Huntington Beach, 

California, from cone penetrometer test data: Bulletin of 

the Seismological Society of America, v. 87, no. 2, p. 

277-293. 

Hart, E.W., and Williams, J.W., 1978, Geologic review 

process, California Geology, v. 31, n. 10, p. 235-236. 

Hatheway, A.W., and Leighton, F.B., 1979, Trenching as an 

exploratory tool, in Hatheway, A.W. and McClure, C.R., 

Jr., editors, Geology in the siting of nuclear power plants: 

Geological Society of America Reviews in Engineering 

Geology, v. IV, p. 169-195. 

Lazarte, C.A., Bray, J.D., Johnson, A.M., and Lemmer, R.E., 

1994, Surface breakage of the 1992 Landers earthquake 

and its effects on structures: Bulletin of the 

Seismological Society of America, v. 84, p. 547-561. 

McCalpin, J.P. (editor), 1996a, Paleoseismology: Academic 

Press, 588 p. 

McCalpin, J.P., 1996b, Field techniques in paleoseismology, 

in McCalpin, J.P., editor, Paleoseismology: Academic 

Press, p. 33-83. 

McCalpin, J.P., 1996c, Paleoseismology in extensional 

environments, in McCalpin, J.P., editor, 

Paleoseismology: Academic Press, p. 85-146. 

National Research Council, 1986, Studies in geophysics --

active tectonics: National Academy Press, Washington, 

D.C., 266 p. (Contains several articles evaluating active 

faulting). 

Pierce, K.L., 1986, Dating Methods, in Studies in geophysics 

-- active tectonics: National Academy Press, Washington, 

D.C., p. 195-214. 

Rutter, N.W., and Catto, N.R., 1995, Dating methods for 

Quaternary deposits: Geological Society of Canada, 

GEOTEXT 2, 308 p. 

Sherard, J.L., Cluff, L.S., and Allen, C.R., 1974, Potentially 

active faults in dam foundations: Geotechnique, Institute 

of Civil Engineers, London, v. 24, n. 3, p. 367-428. 

Slemmons, D.B., 1977, State-of-the-art for assessing 

earthquake hazards in the United States: Report 6, faults 

and earthquake magnitude: U.S. Army Engineer 

Waterways Experiment Station Miscellaneous Paper S73-1, 129 p. with 37 p. appendix. 

Slemmons, D.B. and dePolo, C.M., 1986, Evaluation of 

active faulting and associated hazards, in Studies in 

geophysics -- active tectonics: National Academy Press, 

Washington, D.C., p. 45-62. 

Stephenson, W.J., Rockwell, T.K., Odum, J.K., Shedlock, 

K.M., and Okaya, D.A., 1995, Seismic reflection and 

geomorphic characterization of the onshore Palos Verdes 

fault zone, Los Angeles, California: Bulletin of the 

Seismological Society of America, v. 85, p. 943-950. 
2007 FAULT-RUPTURE HAZARD ZONES IN CALIFORNIA 33

Taylor, C.L., and Cluff, L.S., 1973, Fault activity and its 

significance assessed by exploratory excavation, in

Proceedings of the Conference on tectonic problems of 

the San Andreas fault system: Stanford University 

Publication, Geological Sciences, v. XIII, September 

1973, p. 239-247. 

Utah Section of the Association of Engineering Geologists, 

1987, Guidelines for evaluating surface fault rupture 

hazards in Utah: Utah Geological and Mineral Survey 

Miscellaneous Publication N, 2 p. 

Wallace, R.E., 1977, Profiles and ages of young fault scarps, 

north-central Nevada: Geological Society of America 

Bulletin, v. 88, p. 1267-1281.

Weldon, R.J., II, McCalpin, J.P., and Rockwell, T.K., 1996, 

Paleoseismology of strike-slip tectonic environments, in

McCalpin, J.P., editor, Paleoseismology: Academic 

Press, p. 271-329. 

Yeats, R.S., Sieh, K.E., and Allen, C.A., 1997, Geology of 

Earthquakes: Oxford University Press, New York, N.Y., 

576 p. 

Appendix D 

GENERAL GUIDELINES FOR REVIEWING GEOLOGIC REPORTS 

(These general guidelines are published as DMG Note 41 (1997). Similar guidelines were adopted by

the State Mining and Geology Board for advisory purposes in 1996).

 The purpose of this article is to provide general 

guidance for those geologists who review geologic reports 

of consultants on behalf of agencies having approval 

authority over specific developments. These general 

guidelines are modified from an article titled, “Geologic 

Review Process” by Hart and Williams (1978).

 The geologic review is a critical part of the evaluation 

process of a proposed development. It is the responsibility 

of the reviewer to assure that each geologic investigation, 

and the resulting report, adequately addresses the geologic 

conditions that exist at a given site. In addition to geologic 

reports for tentative tracts and site development, a reviewer 

evaluates Environmental Impact Reports, Seismic Safety 

and Public Safety Elements of General Plans, Reclamation 

Plans, as-graded geologic reports, and final, as-built 

geologic maps and reports. In a sense, the geologic 

reviewer enforces existing laws, agency policies, and 

regulations to assure that significant geologic factors 

(hazards, mineral and water resources, geologic processes) 

are properly considered, and potential problems are 

mitigated prior to project development. Generally, the 

reviewer acts at the discretion or request of, and on behalf 

of a governing agency -- city, county, regional, state, federal 

-- not only to protect the government’s interest but also to 

protect the interest of the community at large. Examples of 

the review process in a state agency are described by 

Stewart and others (1976). Review at the local level has 

been discussed by Leighton (1975), Berkland (1992), 

Larson (1992), and others. Grading codes, inspections, and 

the review process are discussed in detail by Scullin 

(1983). Nelson and Christenson (1992) specifically 

discuss review guidelines for reports on surface faulting. 

THE REVIEWER 

Qualifications 

 In order to make appropriate evaluations of geologic 

reports, the reviewer should be an experienced geologist 

familiar with the investigative methods employed and the 

techniques available to the profession. Even so, the 

reviewer must know his or her limitations, and at times ask 

for the opinions of others more qualified in specialty fields 

(e.g., geophysics, mineral exploitation and economics, 

ground water, foundation and seismic engineering, 

seismology). In California, the reviewer must be licensed 

by the State Board of Registration for Geologists and 

Geophysicists in order to practice (Wolfe, 1975). The 

Board also certifies engineering geologists and 

hydrogeologists, and licenses geophysicists. Local and 

regional agencies may have additional requirements. 
34 CALIFORNIA GEOLOGICAL SURVEY SP 42 

 The reviewer must have the courage of his or her 

convictions and should not approve reports if an inadequate 

investigation has been conducted. Like any review process, 

there is a certain “give-and-take” involved between the 

reviewer and investigator. If there is clear evidence of 

incompetence or misrepresentation in a report, this fact 

should be reported to the reviewing agency or licensing 

board. California Civil Code Section 47 provides an 

immunity for statements made “in the initiation or course of 

any other proceedings authorized by law.” Courts have 

interpreted this section as providing immunity to letters of 

complaint written to provide a public agency or board, 

including licensing boards, with information that the public 

board or agency may want to investigate (see King v. 

Borges, 28 Cal. App. 3d 27 [1972]; and Brody v. 

Montalbano, 87 Cal. App. 3d 725 [1978]). Clearly, the 

reviewer needs to have the support of his or her agency in 

order to carry out these duties. 

 The reviewer should bear in mind that some geologic 

investigators are not accomplished writers, and almost all 

are working with restricted budgets. Also, the reviewer may 

by limited by their agency’s policies, procedures, and fee 

structures. Thus, while a reviewer should demand that 

certain standards be met, he or she should avoid running 

rough-shod over the investigator. The mark of a good 

reviewer is the ability to sort out the important from the 

insignificant and to make constructive comments and 

recommendations. 

 A reviewer may be employed full time by the reviewing 

agency or part-time as a consultant. Also, one reviewing 

agency (such as a city) may contract with another agency 

(such as a county) to perform geologic reviews. The best 

reviews generally are performed by experienced reviewers. 

Thus, the use of multiple, part-time reviewers by a given 

agency tends to prevent development of consistently highquality and efficient reviews. One of the reasons for this is 

that different reviewers have different standards, which 

results in inconsistent treatment of development projects. 

The primary purpose of the review procedure should always 

be kept in mind -- namely, to assure the adequacy of 

geologic investigations. 

Other Review Functions 

 Aside from his or her duties as a reviewer, the 

reviewing geologist also must interpret the geologic data 

reported to other agency personnel who regulate 

development (e.g., planners, engineers, inspectors). Also, 

the reviewing geologist sometimes is called upon to make 

investigations for his or her own agency. This is common 

where a city or county employs only one geologist. In fact, 

some reviewers routinely divide their activities between 

reviewing the reports of others and performing one or 

several other tasks for the employing agency (such as 

advising other agency staff and boards on geologic matters; 

making public presentations) (see Leighton, 1975). 

Conflict of Interest 

 In cases where a reviewing geologist also must perform 

geologic investigations, he or she should never be placed in 

the position of reviewing his or her own report, for that is 

no review at all. A different type of conflict commonly 

exists in a jurisdiction where the geologic review is 

performed by a consulting geologist who also is practicing 

commercially (performing geologic investigations) within 

the same jurisdictional area. Such situations should be 

avoided, if at all possible. 

GEOLOGIC REVIEW 

The Report 

 The critical item in evaluating specific site 

investigations for adequacy is the resulting geologic report. 

A report that is incomplete or poorly written cannot be 

evaluated and should not be approved. As an expediency, 

some reviewers do accept inadequate or incomplete reports 

because of their personal knowledge of the site. However, 

unless good reasons can be provided in writing, it is 

recommended that a report not be accepted until it presents 

the pertinent facts correctly and completely. 

 The conclusions presented in the report regarding the 

geologic hazards or problems must be separate from and 

supported by the investigative data. An indication 

regarding the level of confidence in the conclusions should 

be provided. Recommendations based on the conclusions 

should be made to mitigate those geology-related problems 

which would have an impact on the proposed development. 

Recommendations also should be made concerning the 

need for additional geologic investigations. 

Report Guidelines and Standards 

 An investigating geologist may save a great deal of time 

(and the client’s money), and avoid misunderstandings, if 

he or she contacts the reviewing geologist at the initiation 

of the investigation. The reviewer should not only be 

familiar with the local geology and sources of information, 

he or she also should be able to provide specific guidelines 

for investigative reports and procedures to be followed. 

Guidelines and check-lists for geologic or geotechnical 

reports have been prepared by a number of reviewing 

agencies and are available to assist the reviewer in his or 

her evaluation of reports (e.g., DMG Notes 42, 44, 46, 48, 

and 49; California Department of Conservation, Division of 
2007 FAULT-RUPTURE HAZARD ZONES IN CALIFORNIA 35

Mines and Geology, 1997). A reviewer also may wish to 

prepare his or her own guidelines or check-lists for specific 

types of reviews. 

 If a reviewer has questions about an investigation, 

these questions must be communicated in writing to the 

investigator for response. After the reviewer is satisfied 

that the investigation and resulting conclusions are 

adequate, this should be clearly indicated in writing to the 

reviewing agency so that the proposed development 

application may be processed promptly. The last and one 

of the more important responsibilities of the reviewer 

should be implementation of requirements assuring report 

recommendations are incorporated and appropriate 

consultant inspections are made. 

 The biggest problem the reviewer faces is the 

identification of standards. These questions must be asked: 

“Are the methods of investigation appropriate for a given 

site?” and “Was the investigation conducted according to 

existing standards of practice?” Answers to these questions

lie in the report being reviewed. For example, a reported 

landslide should be portrayed on a geologic map of the site. 

The conclusion that a hazard is absent, where previously 

reported or suspected, should be documented by stating 

which investigative steps were taken and precisely what was 

seen. The reviewer must evaluate each investigative step 

according to existing standards. It should be recognized 

that existing standards of practice generally set minimum 

requirements (Keaton, 1993). Often the reviewer is forced 

to clarify the standards, or even introduce new ones, for a 

specific purpose. 

Depth (Intensity) of Review 

 The depth of the review is determined primarily by the 

need to assure that an investigation and resulting 

conclusions are adequate, but too often the depth of review 

is controlled by the time and funds available. A report on a 

subdivision (e.g., for an EIR or preliminary report) may be 

simply evaluated against a check-list to make certain it is 

complete and well-documented. Additionally, the reviewer 

may wish to check cited references or other sources of data, 

such as aerial photographs and unpublished records. 

 Reviewers also may inspect the development site and 

examine excavations and borehole samples. Ideally, a field 

visit may not be necessary if the report is complete and 

well-documented. However, field inspections are of value, 

and generally are necessary to determine if field data are 

reported accurately and completely. Also, if the reviewer is 

not familiar with the general site conditions, a brief field 

visit provides perspective and a visual check on the reported 

conditions. Whether or not on-site reviews are made, it is 

important to note that the geologic review process is not 

intended to replace routine grading inspections that may be 

required by the reviewing agency to assure performance 

according to an approved development plan. 

Review Records 

 For each report and development project reviewed, a clear, 

concise, and logical written record should be developed. 

This review record may be as detailed as is necessary, 

depending upon the complexity of the project, the geology, 

and the quality and completeness of the reports submitted. 

At a minimum, the record should: 

1. Identify the project, permits, applicant, consultants, 

reports, and plans reviewed; 

2. Include a clear statement of the requirements to be met 

by the parties involved, data required, and the plan, 

phase, project, or report being considered or denied; 

3. Contain summaries of the reviewer’s field 

observations, associated literature and aerial 

photographic review, and oral communications with 

the applicant and the consultant; 

4. Contain copies of any pertinent written 

correspondence; and 

5. The reviewer’s name and license number(s), with 

expiration dates. 

 The report, plans, and review record should be kept in 

perpetuity to document that compliance with local 

requirements was achieved and for reference during future 

development, remodeling, or rebuilding. Such records also 

can be a valuable resource for land-use planning and realestate disclosure. 

Appeals 

 In cases where the reviewer is not able to approve a 

geologic report, or can accept it only on a conditional basis, 

the developer may wish to appeal the review decision or 

recommendations. However, every effort should be made to 

resolve problems informally prior to making a formal 

appeal. An appeal should be handled through existing 

local procedures (such as a hearing by a County Board of 

Supervisors or a City Council) or by a specially appointed 

Technical Appeals and Review Panel comprised of 

geoscientists, engineers, and other appropriate 

professionals. Adequate notice should be given to allow 

time for both sides to prepare their cases. After an 
36 CALIFORNIA GEOLOGICAL SURVEY SP 42 

appropriate hearing, the appeals decision should be in 

writing as part of the permanent record. 

 Another way to remedy conflicts between the 

investigator and the reviewer is by means of a third party 

review. Such a review can take different paths ranging from 

the review of existing reports to in-depth field 

investigations. Third party reviews are usually done by 

consultants not normally associated with the 

reviewing/permitting agency. 

REFERENCES 

Berkland, J.O., 1992, Reviewing the geologic review 

process at the county level, in Stout, M.L., editor, 

Association of Engineering Geologists Proceedings, 

35th Annual Meeting, p. 333-336. 

California Department of Conservation, Division of Mines 

and Geology DMG Notes: 

DMG NOTE 41 - General guidelines for reviewing 

geologic reports, 1997. 

DMG NOTE 42 - Guidelines to geologic/seismic reports, 

1986. 

DMG NOTE 44 - Recommended guidelines for preparing 

engineering geologic reports, 1986. 

DMG NOTE 46 - Guidelines for geologic/seismic 

considerations in environmental impact reports, 1986. 

DMG NOTE 48 - Checklists for the review of 

geologic/seismic reports for California public schools, 

hospitals and essential services buildings, 1997. 

DMG NOTE 49 - Guidelines for evaluating the hazard of 

surface fault rupture, 1997 (see Appendix C). 

California Department of Conservation, Division of Mines 

and Geology, 1997, Guidelines for evaluating and 

mitigating seismic hazards in California: Special 

Publication 117, 74 p. 

Hart, E.W., and Williams, J.W., 1978, Geologic review 

process: California Geology, v. 31, p. 235-236. 

Keaton, J.R., 1993, Environmental and engineering geology 

practice from the technical-professional society 

perspective: AEG News, Fall 1993, v. 36, no. 4, p. 19-

21. 

Larson, R.A., 1992, A philosophy of regulatory review, in

Stout, M.L., editor, Association of Engineering 

Geologists Proceedings, 35th Annual Meeting, p. 224-

226. 

Leighton, F.B., 1975, Role of geotechnical consultants and 

reviewers for the County of San Mateo: California 

Geology, v. 28, p. 178-181. 

Nelson, C.V., and Christenson, G.E., 1992, Establishing 

guidelines for surface fault rupture hazard 

investigations -- Salt Lake County, Utah, in Stout, 

M.L., editor, Association of Engineering Geologists 

Proceedings, 35th Annual Meeting, p. 242-249.

Rogers, J.D,. and Olshansky, R.B., 1992, Science versus 

advocacy -- the reviewers role to protect the public 

interest, in Stout, M.L., editor, Association of 

Engineering Geologists Proceedings, 35th Annual 

Meeting, p. 371-378. 

Scullin, C.M., 1983, Excavation and grading code 

administration, inspection, and enforcement: PrenticeHall, Inc., Englewood Cliffs, New Jersey, 405 p. 

Stewart, R.M., Hart, E.W., and Amimoto, P.Y., 1976, The 

review process and the adequacy of geologic reports: 

Bulletin of the International Association of 

Engineering Geology, n. 14, p. 83-88. (Reprinted in 

California Geology, October 1977, v. 30, p. 224-229). 

Wolfe, J., 1975, More on registration: California Geology, 

v. 28, p. 155-156. 
2007 FAULT-RUPTURE HAZARD ZONES IN CALIFORNIA 37

Appendix E 

PRODUCTS OF THE FAULT EVALUATION AND ZONING PROGRAM 

 Since the passage of the AP Act, staff of the Fault 

Evaluation and Zoning Program have published numerous 

reports on the Act and the surface fault rupture hazard. These, 

as well as unpublished files of geologic information, are listed 

below. A notation next to each entry is the publication 

number: CD – California Geological Survey compact disc, CG 

-- California Geology, N – DMG/CGS Note, SP -- Special 

Publication, SR -- Special Report, o.p. -- report is out of print, 

* -- an outside publication not available from CGS. Numbers 

alone (e.g., 89-16) are Open-File Report numbers. The 

publications are listed chronologically by groups below. 

AVAILABILITY 

Reports listed here are available for reference at offices of 

the California Geological Survey in Sacramento, Menlo Park, 

and Los Angeles. Some reports are also available for reference 

at county and university libraries. Copies of available CGS 

reports may be purchased by mail order or over-the-counter 

from any office (see exceptions below): 

OFFICES OF THE 

CALIFORNIA GEOLOGICAL SURVEY

GEOLOGIC INFORMATION AND PUBLICATIONS 

801 K Street, MS 14-34 

Sacramento, CA 95814 

(916) 445-5716 

BAY AREA REGIONAL OFFICE 

345 Middlefield Road, MS 520 

Menlo Park, CA 94025 

(650) 688-6327 

SOUTHERN CALIFORNIA REGIONAL OFFICE 

888 South Figueroa Street, Suite 475 

Los Angeles, CA 90017 

(213) 239-0878 

IMPLEMENTATION OF THE ALQUIST-PRIOLO ACT 

Official Maps of Earthquake Fault Zones, by California 

Geological Survey, 1974-2007. As of August 2007, 547 

new and revised Official APEFZ maps have been issued. 

Special Publication 42 provides an index to these maps 

and describes how they can be purchased. 

SP 42 Fault-rupture hazard zones in California, by W.A. 

Bryant and E.W. Hart, 2007, 42 p. (pdf version only). 

Includes an index map which identifies all 7.5-minute 

topographic maps in which AP Earthquake Fault 

Zones are located. (Revised periodically). 

CG Zoning for surface fault hazards in California --

The New Special Studies Zones maps, by E.W. 

Hart, 1974: v. 27, n. 10, p. 227-230. 

SP 47 Active fault mapping and evaluation program –

o.p. 10-year program to implement Alquist-Priolo 

Special Studies Zones Act, 1976. 

CG The review process and the adequacy of geologic 

reports, by R.M. Stewart, E.W. Hart, and P.Y. 

Amimoto, 1976: Bulletin of the International 

Association of Engineering Geology, n. 14, p. 83-88. 

(Reprinted in California Geology, v. 30, n. 10, p. 224-

229). 

CG Geologic review process, by E.W. Hart and J.W. 

Williams, 1978: v. 31, n. 10, p. 235-236.

* Zoning for the hazard of surface fault rupture in 

California, by E.W. Hart, 1978, in Proceedings of 

the Second International Conference on 

Microzonation, San Francisco, November 26-

December 1, 1978: NSF Special Publication, p. 635-

645. 

CG Fault Evaluation and Zoning Program, by E.W. 

Hart, 1980: v. 33, n. 7, p. 147-152. 

* Zoning for surface-faulting in California, by E.W. 

Hart, 1986, in Proceedings of Conference XXXII --

Workshop on future directions in evaluating 

earthquake hazards in southern California, November 

12-13, 1985: U.S. Geological Survey Open-File 

Report 86-401, p. 74-83. 

90-18 A study of the effectiveness of the Alquist-Priolo 

Program, by R. Reitherman and D.J. Leeds, 1990. 

N 41 General guidelines for reviewing geologic reports,

by E.W. Hart and W.A. Bryant, 1997. (Also 

Appendix D in SP 42). 
38 CALIFORNIA GEOLOGICAL SURVEY SP 42 

N 49 Guidelines for evaluating the hazard of surface 

fault rupture, by E.W. Hart and W.A. Bryant 1997. 

(Also Appendix C in SP 42). 

CD 2000-03 - Digital images of official maps of AlquistPriolo Earthquake Fault Zones of California, 

Southern Region, by DMG staff, 2000. 

CD 2000-04 - Digital images of official maps of AlquistPriolo Earthquake Fault Zones of California, 

Central Coastal Region, by DMG staff, 2000. 

CD 2000-05 - Digital images of official maps of AlquistPriolo Earthquake Fault Zones of California, 

Northern and Eastern Region, by DMG staff, 2000. 

CD 2001-04 - GIS files of official Alquist-Priolo 

Earthquake Fault Zones, Central Coastal Region, 

developed by W.A. Bryant, R. Martin, P.Wong, D. 

Maldonado, J. Wampole, and D. Dixon, 2001.

CD 2001-05 - GIS files of official Alquist-Priolo 

Earthquake Fault Zones, Southern Region, 

developed by W.A. Bryant, R. Martin, P.Wong, D. 

Maldonado, J. Wampole, and D. Dixon, 2001.

CD 2001-06 - GIS files of official Alquist-Priolo 

Earthquake Fault Zones, Northern and Eastern 

Region, developed by W.A. Bryant, R. Martin, 

P.Wong, D. Maldonado, J. Wampole, and D. Dixon, 

2001. 

POST-EARTHQUAKE INVESTIGATIONS 

CG Ground rupture associated with faulting --

Oroville earthquake, August 1975, by E.W. Hart, 

1975: v. 28, p. 274-276.

SR 124 Ground rupture along the Cleveland Hill fault, by 

E.W. Hart and J.S. Rapp, 1975, in Sherburne, R.W. 

and Hauge, C.J., editors, Oroville, California, 

Earthquake 1 August 1975, p. 61-72. 

* Geologic setting, historical seismicity and surface 

effects of the Imperial Valley earthquake, October 

15, 1979, Imperial County, California, by E. 

Leivas, E.W. Hart, R.D. McJunkin, and C.R. Real, 

1980, in Imperial County, California, Earthquake 

October 15, 1979: EERI Reconnaissance Report, 

February 1980, p. 5-19. 

81-5 Preliminary map of October 1979 fault rupture, 

Imperial and Brawley faults, Imperial County, 

California, by E.W. Hart, 1981. 

80-12 Preliminary map of surface rupture associated 

o.p. with the Mammoth Lakes earthquakes, May 25 

and 27, 1980, by W.A. Bryant, G.C. Taylor, E.W. 

Hart, and J.E. Kahle, 1980. 

SR 150 Surface rupture associated with the Mammoth 

Lakes earthquakes of 25 and 27 May, 1980, by 

G.C. Taylor and W.A. Bryant, 1980, in Sherburne, 

R.W., editor, Mammoth Lakes, California 

earthquakes of May 1980, p. 49-67. 

SR 150 Rockfalls generated by the Mammoth Lakes 

earthquakes of May 25 and 27, 1980, by W.A. 

Bryant, 1980, in Sherburne, R.W., editor, Mammoth 

Lakes, California earthquakes of May 1980, p. 69-73.

SR 150 Planned zoning of active faults associated with the 

Mammoth Lakes earthquakes of May 1980, by 

E.W. Hart, 1980, in Sherburne, R.W., editor, 

Mammoth Lakes, California earthquakes of May 

1980, p. 137-141. 

CG Ground rupture, Coalinga earthquake of 10 June 

1983, by R.D. McJunkin and E.W. Hart, 1983: v. 36, 

n. 8, p. 182-184. 

SP 66 Surface faulting northwest of Coalinga, 

California, June and July 1983, by E.W. Hart and 

R.D. McJunkin, 1983, in Bennett, J.H. and 

Sherburne, R.W., editors, The 1983 Coalinga, 

California earthquakes, p. 201-219. 

SP 68 Evidence for surface faulting associated with the 

Morgan Hill earthquake of April 24, 1984, by 

E.W. Hart, 1984, in Bennett, J.H. and Sherburne, 

R.W., editors, The 1984 Morgan Hill, California 

earthquake, p. 161-173. 

CG Fault rupture associated with the July 21, 1986 

Chalfant Valley Earthquake, Mono and Inyo 

counties, California, by J.E. Kahle, W.A. Bryant, 

and E.W. Hart, 1986: v. 39, n. 11, p. 243-245. 

CG Magnitude 5.9 North Palm Springs earthquake, 

July 8, 1986, Riverside County, California: 

Lifeline damage, by G. Borchardt and M.W. 

Manson, 1986: v. 39, n. 11, p. 248-252. 

CG Preliminary report: Surface rupture, Superstition 

Hills earthquakes of November 23 and 24, 1987,

by J.E. Kahle, C.J. Wills, E.W. Hart, J.A. Treiman, 

R.B. Greenwood, and R.S. Kaumeyer, 1988: v. 41, n. 

4, p. 75-84. 
2007 FAULT-RUPTURE HAZARD ZONES IN CALIFORNIA 39

CG Liquefaction at Soda Lake: Effects of the 

Chittenden earthquake swarm of April 18, 1990, 

Santa Cruz County, California, by C.J. Wills and 

M.W. Manson, 1990: v. 43, n. 10, p. 225-232. 

* Surface fissures and the mapping of CDMG 

Special Studies Zones, by E.W. Hart, 1990, in Reid, 

G., editor, What we have learned from the October 17, 

1989 7.1M Loma Prieta earthquake: 16th Annual 

Saber Society Symposium Proceedings Volume, p. 

87-99. 

SP 104 The search for fault rupture and the significance 

of ridge-top fissures, Santa Cruz Mountains, 

California, by E.W. Hart, W.A. Bryant, C.J. Wills, 

and J.A. Treiman, 1990, in McNutt, S.R. and Sydnor, 

R.H., editors, The Loma Prieta Earthquake of October 

17, 1989, p. 83-94. 

CG The Mono Lake earthquake of October 23, 1990,

by S.R. McNutt, W.A. Bryant, and R. Wilson, 1991: 

v. 44, n. 2, p. 27-32. 

* Eureka Peak and Burnt Mountain faults, two 

“new” faults in Yucca Valley, San Bernardino 

County, California, by J.A. Treiman, in Landers 

earthquake of June 28, 1992, San Bernardino County, 

California, Field Trip Guidebook: Southern 

California Section of Association of Engineering 

Geologists, 1992, p. 19-22. 

CG Surface faulting associated with the June 1992 

Landers earthquake, California, by E.W. Hart, 

W.A. Bryant, and J.A. Treiman, 1993, v. 46, p. 10-16. 

SP 116 The search for fault rupture after the Northridge 

earthquake, by E.W. Hart, J.A. Treiman, and W.A. 

Bryant, 1995, in Woods, M.C. and Seiple, W.R., 

editors, The Northridge, California, earthquake of 17 

January 1994, p. 89-101. 

SP 116 Surface faulting near Santa Clarita, by J.A. 

Treiman, 1995, in Woods, M.C. and Seiple, W.R., 

editors, The Northridge, California, earthquake of 17 

January 1994, p. 103-110. 

* Primary surface rupture associated with the Mw 

7.1 October 1999 Hector Mine earthquake, San 

Bernardino County, California, by J.A. Treiman, 

K.J. Kendrick, W.A. Bryant, T.K. Rockwell, and S.F. 

McGill, 2002, Bulletin of the Seismological Society 

of America, v. 92, p. 1171-1191. 

* Surface fault slip associated with the 2004 

Parkfield, California, earthquake, by M.J. Rymer, 

J.C. Tinsley III, J.A. Treiman, J.R. Arrowsmith, K.B. 

Clahan, A.M. Rosinski, W.A. Bryant, A. Snyder, G.S. 

Fuis, N.A. Toke, and G.W. Bawden, 2006, Bulletin 

of the Seismological Society of America, v. 96, p. 

S11-S27. 

STUDIES OF INDIVIDUAL FAULTS 

FERs Fault Evaluation Reports, by Fault Evaluation and 

Zoning Project Staff, 1976-2007, copies of the FERs 

are available for reference in the Bay Area and 

Southern California regional offices of CGS. An 

index to FERs and copies of FERs through 1989 on 

microfiche are available as Open-File Reports 90-9 to 

90-14 (see below). FERs completed through 2000 

have been digitally archived and are available for 

purchase (see below). 

81-6 Evidence of Holocene movement of the San 

Andreas fault zone, northern San Mateo County, 

California, by T.C. Smith, 1981. 

81-7 Sargent, San Andreas, and Calaveras fault zones: 

Evidence for recency in the Watsonville East, 

Chittenden and San Felipe quadrangles, 

California, by W.A. Bryant, D.P. Smith, and E.W. 

Hart, 1981. 

81-8 Recently active strands of the Greenville fault, 

Alameda, Contra Costa and Santa Clara counties, 

California, by E.W. Hart, 1981. 

81-9 Evidence for recent faulting, Calaveras and 

Pleasanton faults, Diablo and Dublin 

quadrangles, California, by E.W. Hart, 1981. 

SP 62 Southern Hayward fault zone, Alameda and 

Santa Clara counties, California, by W.A. Bryant, 

1982, in Proceedings -- Conference on earthquake 

hazards of the eastern San Francisco Bay area, p. 35-

44. 

* Self-guided field trip No. 4 -- Fault creep along 

the Hayward fault in the Richmond-San Pablo area, 

by T.C. Smith, 1982, in Conference on earthquake 

hazards of the [eastern] San Francisco Bay area, Field 

Trip Guidebook: California State University, 

Hayward. 

84-54 Evidence of recent faulting along the Owens 

Valley, Round Valley, and White Mountains fault 

zones, Inyo and Mono counties, California, by 

W.A. Bryant, 1984. 

84-55 Evidence of recent faulting along the Mono Lake 

fault zone, Mono County, California, by W.A. 

Bryant, 1984. 
40 CALIFORNIA GEOLOGICAL SURVEY SP 42 

84-56 Evidence of recent faulting along the Antelope 

Valley fault zone, Mono County, California, by 

W.A. Bryant, 1984. 

88-14 Recently active traces of the Newport-Inglewood 

fault zone, Los Angeles and Orange counties, 

California, by W.A. Bryant, 1988. 

CG A neotectonic tour of the Death Valley fault zone, 

by C.J. Wills, 1989: v. 42, n. 9, p. 195-200. 

CG Deep Springs fault, Inyo County, California, An 

example of the use of relative-dating techniques,

by W.A. Bryant, 1989: v. 42, n. 11, p. 243-255. 

* The Rose Canyon fault zone; a historical review, 

by J.A. Treiman, 1989, in Seismic risk in the San 

Diego region, a workshop on the Rose Canyon fault 

system: Proceedings volume of a workshop sponsored 

by the Southern California Earthquake Preparedness 

Project, June 29-30, 1989. 

90-9 Index to fault evaluation reports prepared 1976-

1989 under the Alquist-Priolo Special Studies 

Zones Act, by C.J. Wills, P. Wong, and E.W. Hart, 

1990. 

90-10 Microfiche copies of Fault Evaluation Reports for 

northern California, by Division of Mines and 

Geology staff. 

90-11 Microfiche copies of Fault Evaluation Reports for 

the southern Coast Ranges, by Division of Mines 

and Geology staff. 

90-12 Microfiche copies of Fault Evaluation Reports for 

the Transverse Ranges, by Division of Mines and 

Geology staff. 

90-13 Microfiche copies of Fault Evaluation Reports for 

the Peninsular Ranges, by Division of Mines and 

Geology staff. 

90-14 Microfiche copies of Fault Evaluation Reports for 

eastern California, by Division of Mines and 

Geology staff. 

CG Active faults north of Lassen Volcanic National 

Park, by C.J. Wills, 1991, v. 44, p. 51-58. 

* The Green Valley Fault, by W.A. Bryant, in Field 

trip guide to the geology of western Solano County: 

Northern California Geological Society, 1991, p. 1-

10. 

SP 113 Progress in understanding the Concord fault 

through site specific studies, by C.J. Wills and E.W. 

Hart, in Proceedings -- Conference on earthquake 

hazards in the eastern San Francisco Bay area, 1992, 

p. 311-317. 

SP 113 The elusive Antioch fault, by C.J. Wills, in

Proceedings -- Conference on earthquake hazards in 

the eastern San Francisco Bay area, 1992, p. 325-331. 

SP 113 Pseudo-mole tracks from clay beds east of 

Healdsburg, by M.D. Malone, G. Borchardt, E.W. 

Hart, and S.R. Korbay, in Proceedings -- Conference 

on earthquake hazards in the eastern San Francisco 

Bay area, 1992, p. 419-425. 

92-7 Recently active traces of the Rodgers Creek fault, 

Sonoma County, California, by E.W. Hart, 1992, 

14 p. 

93-2 The Rose Canyon fault zone, southern California, 

by J.A. Treiman, 1993, 45 p. 

* Holocene slip rate and earthquake recurrence on 

the Honey Lake fault zone, northeastern 

California, by C.J. Wills and G. Borchardt, 1993, 

Geology, v. 21, p. 853-856. 

CD 2002-01 - Fault evaluation reports prepared under the 

Alquist-Priolo Earthquake Fault Zoning Act, 

Region 1 – Central California, developed by W.A. 

Bryant and P. Wong, 2002.

CD 2002-02 - Fault evaluation reports prepared under the 

Alquist-Priolo Earthquake Fault Zoning Act, 

Region 2 – Southern California, developed by W.A. 

Bryant and P. Wong, 2002.

CD 2002-03 - Fault evaluation reports prepared under the 

Alquist-Priolo Earthquake Fault Zoning Act, 

Region 3 – Northern and Eastern California, 

developed by W.A. Bryant and P. Wong, 2002. 

REGIONAL SUMMARY REPORTS 

77-8 Summary report -- Fault evaluation program, 

1976 area (western Transverse Ranges), by E.W. 

Hart, E.J. Bortugno, and T.C. Smith, 1977. 

78-10 Summary report -- Fault evaluation program, 

1977 area (Los Angeles Basin region), by E.W. 

Hart, D.P. Smith, and T.C. Smith, 1978. 

79-10 Summary report -- Fault evaluation program, 

1978 area (Peninsular Ranges-Salton Trough 

region), by E.W. Hart, D.P. Smith, and R.B. Saul, 

1979.
2007 FAULT-RUPTURE HAZARD ZONES IN CALIFORNIA 41

81-3 Summary report -- Fault evaluation program, 

1979-1980 area (southern San Francisco Bay 

region), by E.W. Hart, W.A. Bryant, and T.C. Smith, 

1981. 

SP 62 California’s fault evaluation program -- southern 

San Francisco Bay region, by E.W. Hart, T.C. 

Smith, and W.A. Bryant, 1982, in Proceedings --

Conference on earthquake hazards in the eastern San 

Francisco Bay area, p. 395-404.

83-10 Summary report -- Fault evaluation program, 

1981-1982 area (northern Coast Ranges region), 

by E.W. Hart, W.A. Bryant, and T.C. Smith, 1983. 

84-52 Summary report -- Fault evaluation program, 

1983 area (Sierra Nevada region), by E.W. Hart, 

W.A. Bryant, and T.C. Smith, 1984. 

86-3 Summary report -- Fault evaluation program, 

1984-1985, southern Coast Ranges region and 

other areas, by E.W. Hart, W.A. Bryant, M.W. 

Manson, and J.E. Kahle, 1986. 

88-1 Summary report -- Fault evaluation program, 

1986-1987, Mojave Desert region and other areas, 

by E.W. Hart, W.A. Bryant, J.E. Kahle, M.W. 

Manson, and E.J. Bortugno, 1987. 

89-16 Summary report -- Fault evaluation program, 

1987-1988, southwestern Basin and Range region 

and supplemental areas, by E.W. Hart, W.A. 

Bryant, C.J. Wills, J.A. Treiman, and J.E. Kahle, 

1989. 

91-9 Summary report -- Fault evaluation program, 

1989-1990, northeastern California and 

supplemental areas, by E.W. Hart, W.A. Bryant, 

J.A. Treiman, C.J. Wills, and R.H. Sydnor, 1991. 

CONSULTANTS REPORTS 

A-P File, reports by consulting geologists, 1974-2007; 

reports for sites within Earthquake Fault Zones submitted 

to the California Geological Survey in compliance with 

the APEFZ Act. Over 4,000 reports on file. Reports filed 

with CGS through 2000 have been digitally archived and 

are available for purchase (see below). Reports filed after 

2000 are available for reference at the Geologic 

Information and Publications Office in Sacramento. 

C File, reports by consulting geologists that predate the 

Earthquake Fault Zones or are outside the Zones at the 

time of the study. Over 600 reports on file. Reports are 

available for reference at the Bay Area and Southern 

California regional offices of CGS, and the Geologic 

Information and Publications Office in Sacramento. 

77-6 Index to geologic reports for sites within Special 

o.p. Studies Zones, by W.Y.C. Lo and J.G. Moreno, 1977 

(superseded by OFR 84-31). 

84-31 Index to geologic reports for sites within Special 

Studies Zones, by P. Wong, 1984. (Index map to the 

AP File reports). 

89-5 Index to geologic reports for development sites 

within Special Studies Zones in California, July 1, 

1984 to December 31, 1988, by P. Wong, 1989. 

(Update for OFR 84-31). 

90-15 Directory of fault investigation reports for 

development sites within Special Studies Zones in 

California, 1974-1988, by P. Wong, E.W. Hart, and 

C.J. Wills, 1990. (Listing of all AP File reports 

through December 1988). 

95-9 Index to geologic reports for development sites 

within Earthquake Fault Zones in California, 

January 1, 1989 to December 31, 1994, by P. 

Wong, 1995 (Update for OFR 89-5). 

CD 2003-01 - Fault investigation reports for development 

sites within Alquist-Priolo Earthquake Fault 

Zones in Northern California, 1974-2000, 

developed by P. Wong, W.A. Bryant, and J.A. 

Treiman, 2003. 

CD 2003-02 - Fault investigation reports for development 

sites within Alquist-Priolo Earthquake Fault 

Zones in Southern California, 1974-2000, 

developed by P. Wong, W.A. Bryant, and J.A. 

Treiman, 2003.
42 CALIFORNIA GEOLOGICAL SURVEY SP42 

Appendix F 

WAIVER PROCEDURE FOR THE ALQUIST-PRIOLO ACT

Section 2623 of the Act states, “If the city or county 

[having jurisdiction over the lands] finds that no undue [fault] 

hazard...exists, the geologic report on such hazard may be 

waived, with approval of the State Geologist.” The location 

of the proposed development or structure may be approved 

following such waiver. 

 The State Geologist will review waiver requests only after 

receiving the Waiver Form completed by the city or county 

geologist and the property owner, and accompanied by 

supporting statements and data in writing that would justify 

approval of the waiver request.