GEOLOGICAt SURVEY CIRCULAR 525
COVER:

Looking northwest along the Hayward fault zone from Oakland to Berkeley, Calif. Lake Temescal in middle

foreground, San Francisco Bay in background. Photograph courtesy Clyde Sunderland, aerial photographer.

Oakland.
TECTONIC CREEP IN THE

HAYWARD FAULT ZONE

CALIFORNIA
View looking northwest along the Hayward fault zone (dotted), Fremont to Oakland. Irvington district of hremont in loreground. banrrancisc 

Bay in background. Photograph courtesy Clyde Sunderland, aerial photographer, Oakland.
Tectonic Creep in the 

Hayward Fault Zone 

California

INTRODUCTION

By Dorothy H. Radbruch and M. G. Bonilla

DAMAGE TO CULVERT UNDER MEMORIAL STADIUM 

UNIVERSITY OF CALIFORNIA, BERKELEY

By Dorothy H. Radbruch and Ben J. Lennert, Lennert and Associates

CRACKS IN THE CLAREMONT WATER TUNNEL

By F. B. Blanchard and C. L. Laverty, East Bay Municipal Water District

DEFORMATION OF RAILROAD TRACKS IN FREMONT, CALIFORNIA 

By M. G. Bonilla

CREEP IN THE IRVINGTON DISTRICT, FREMONT, CALIFORNIA

By Lloyd S. Cluff, Woodward-Clyde-Sherard and Associates 

and Karl V. Steinbrugge, Pacific Fire Rating Bureau

Geological Survey Circular 525

Washington 7966
United States Department of the Interior

WALTER J. NICKEL, Secretary

Geological Survey

William T. Pecora, Director

First printing 1966

Second printing 1966

Third printing 1966

Fourth printing 1968

Fifth printing 1970

Free on application to the U.S. Geological Survey, Washington, D.C. 20242
CONTENTS

Page Page

Abstract ______ ______________________ 1 Deformation of railroad tracks in

Introduction _________________________ 1 Fremont, California _______________ 6

Damage to culvert under Memorial Creep in the Irvington district,

Stadium, University of California, Fremont, California ______-_____-_- 8

Berkeley __________________________ 3 Selected references________--__-__-.._ 12

Cracks in the Claremont water tunnel___ 6

ILLUSTRATIONS

Page

Frontispiece. View looking northwest along the Hayward fault zone, Fremont to Oakland. 

Figure 1. Index map showing location of Hayward, San Andreas, and Calaveras fault zones

and approximate boundaries of figure 2 ____________________________________ VI

2. Map showing approximate location of fault traces of the Hayward fault zone and

localities where evidence of creep has been found __________________________ 2

3. Sketch map showing location of University of California Memorial Stadium,

Berkeley; fault or shear zone within the Hayward fault zone; two Strawberry 

Creek culverts, with station designations on culverts; and location of major 

cracking of stadium culvert __________________________-_-_---_-------_----- 4

4. Sketch indicating general relationship of fault to damaged culvert under the

University of California Memorial Stadium, relative direction of movement

of opposite sides of fault, and nature of damage to culvert ____________________ 5

5. Map showing zone of principal deformation of Western Pacific and Southern

Pacific railroad tracks ____________________________________ ______________ 7

6. Photographs showing deformation of Southern Pacific siding by creep on the

Hayward fault ___________________________________________________________ 7

7. View westward along Western Pacific tracks showing deformation of rails

by creep on the Hayward fault _________________________--__--__--------_--- 8

8. View looking southeast along strike of the Hayward fault zone near Irvington

district, Fremont ________________________________________________________ 9

9. View looking southeast along strike of Hayward fault, showing sag pond along the

trace of the fault and a building extending into the fault zone __________________ 10

10. Line drawing showing general configurations of damaged building and nearby

offset fence-----------_----_-_--_-----_-_------_------------__---_---_-_- 11

11. View looking northeast and almost perpendicular to strike of fault inside

building straddling fault ____________________________-_----------------_--- 11

12. View looking west and nearly perpendicular to fault along inside south wall of

building _________________________________________________________________ 12

V
VI

}22°30 121°30'

38°00'

37°30'

37°00'

Figure 1. Location of Hayward, San Andreas, and Calaveras fault zones, and approximate boundaries of figure 2. The towns of Niles, 

Irvington, and Warm Springs are now districts within the larger town of Fremont.
Tectonic Creep in the Hayward Fault Zone

California

ABSTRACT

Tectonic creep is slight apparently continuous movement 

along a fault. Evidence of creep has been noted at several 

places within the Hayward fault zone a zone trending northwestward near the western front of the hills bordering the 

east side of San Francisco Bay.

D. H. Radbruch of the Geological Survey and B. J. Lennert, 

consulting engineer, confirmed a reported cracking of a culvert under the University of California stadium.

F. B. Blanchard and C. L. Laverty of the East Bay Municipal Utility District of Oakland studied cracks in the Claremont water tunnel in Berkeley.

M. G. Bonilla of the Geological Survey noted deformation 

of railroad tracks in the Niles district of Fremont. Six sets 

of tracks have been bent and shifted.

L. S. Cluff of Woodward-Clyde-Sherard and Associates and 

K. V. Steinbrugge of the Pacific Fire Rating Bureau noted 

that the concrete walls of a warehouse in the Irvington district of Fremont have been bent and broken, and the columns 

forced out of line.

All the deformations noted have been right lateral and 

range from about 2 inches in the Claremont tunnel to about 

8 inches on the railroad tracks. Tectonic creep almost certainly will continue to damage buildings, tunnels, and other 

structures that cross the narrow bands of active movement 

within the Hayward fault zone.

INTRODUCTION

BY DOROTHY H. RADBRUCH AND M. G. BONILLA

Tectonic creep has recently been recognized in the Hayward fault zone (fig. 1). Tectonic creep is here considered to be slight 

apparently continuous movement along a 

fault, usually not accompanied by felt earthquakes; it has also been called slippage 

(Whitten and Claire, 1960). Much construction is going on in the areas of creep, and the 

probability of damage due to slow movement 

of faults, in addition to the possibility of 

sudden rupture, should be brought to the attention of persons concerned with design, 

construction, or maintenance of structures 

in the Hayward fault zone.

The Hayward fault zone is a northwesttrending zone of faults near the western front 

of the hills bordering the east side of San 

Francisco Bay (fig. 2). It extends southeastward from San Pablo to Warm Springs, and 

possibly even farther both northwestward 

and southeastward. The zone in which recent 

movement has taken place ranges in width 

from approximately 500 feet south of Lake 

Temescal to about 1-3/4 miles near the Mission San Jose district. Many of the faults 

within the zone are actually bands of sheared 

rock, tens or possibly even hundreds of feet 

wide, in which are many anastomosing fault 

surfaces.

In places the surface expression of the 

many faults within the fault zone is very obvious. Near San Pablo the course of a fault 

is indicated by a short valley southeast of 

the Mira Vista Country Club; near the University of California in Berkeley and at 

Decoto the steep west ward-facing front of 

the hills is probably a fault scarp. Lake 

Temescal in Oakland lies in a pronounced 

trench which shows the course of the fault 

zone, and between Niles and Irvington the 

main fault trace is marked by two conspicuous sag ponds. In general, the extent of the 

zone is indicated by such geomorphic features as shutter ridges, offset streams, lines 

of springs, scarps, and sag ponds.

In historic time, movements within the 

fault zone have caused two major earthquakes with accompanying surface rupture 

one in 1836 and one in 1868 (Wood, 1916) and 

numerous small shocks (Tocher, 1959). Both 

horizontal and vertical movement were reported at the time of the 1868 shock.

During the last few years evidence of tectonic creep along the Hayward fault zone has
TECTONIC CREEP IN THE HAYWARD FAULT ZONE. CALIFORNIA

122° 00'

Figure 2. Approximate location of fault traces of the Hayward fault zone and localities (A-D) where evidence of creep has been found.
INTRODUCTION

been found independently by several people 

from different organizations. In 1960, L. S. 

Cluff of Woodward-Clyde-Sherard and Associates noted distortion of a warehouse (loc. 

D, fig. 2) in the Irvington district of Fremont. 

In December 1964 the East Bay Municipal 

Utility District found offsets in the Claremont water tunnel (loc. B, fig. 2) in Berkeley 

while the tunnel was temporarily drained. In 

March 1965 M. G. Bonilla of the U.S. Geological Survey found distortion in railroad 

tracks (loc. C, fig. 2) in the Niles district of 

Fremont. More recently, D. H. Radbruch of 

the U.S. Geological Survey and Ben J. Lennert, consulting engineer, confirmed a reported cracking of the culvert (loc. A, fig. 2) 

under the University of California stadium in 

Berkeley. In each area the movement has 

been right lateral; that is, the northeast side 

of the fault has moved southeastward with 

respect to the southwest side of the fault.

As may be seen from figure 2, these four 

areas are near the ends of a 28-mile segment of the Hayward fault zone, but creep 

may be occurring in the intervening reaches. 

It is hoped that publicizing this phenomenon 

will encourage others to look for similar 

movements in other parts of the zone.

Faults do not suddenly change their habits, 

and therefore additional major earthquakes 

and tectonic creep along the Hayward fault 

zone can be expected. Future movement will 

probably take place within the fairly narrow 

band where historic movement and present 

creep are known. Direct injury to persons 

as a result of creep is not likely, but creep 

may progressively weaken structures which 

could fail and cause injuries.

The recognition, by geologic studies, of 

narrow bands of active movement permits 

(1) concentration of measurement for scientific and practical uses, and (2) precautions 

to minimize the destructive effects of the 

movement.

The following sections of this circular 

describe in detail, from north to south, the 

four areas of creep that have thus far been 

observed.

DAMAGE TO CULVERT UNDER MEMORIA 

STADIUM, UNIVERSITY OF CALIFORNIA, 

BERKELEY

BY DOROTHY H. RADBRUCH AND BEN J. LENNERT 1

The Hayward fault zone has long been 

known to extend northwestward across the 

campus of the University of California at 

Berkeley (Buwalda, 1929; G. D. Louderback, 

unpub. data). The University of California 

Memorial Stadium lies directly on the fault 

zone, its long axis being roughly parallel to 

it, at a spot where right-lateral movement 

along a sheared band or fault plane has offset the southwest-trending canyon of Strawberry Creek. The southwest side of the fault 

has moved northwest with respect to the 

northeast side, so that the downstream part 

of Strawberry Creek is now northwest of the 

upstream part. The two parts are connected 

by a northwest-trending section, about 1,200 

feet, which flows in a culvert under the stadium. Part of the water of Strawberry Creek 

is carried by a bypass culvert which extends across the fault northwest of the stadium (fig. 3).

On June 23, 1965, Dorothy H. Radbruch, of 

the U.S. Geological Survey, and Ben J. Lennert, of Lennert and Associates, soils engineers, consultants to the University of California, examined both of the Strawberry 

Creek drainage culverts.

The following description of damage to the 

culverts and their history of construction, 

damage, and repair is derived in part from 

field observation and in part from correspondence, reports, and drawings kindly furnished by the Division of Architecture and 

Engineering of the University of California 

and by Walter T. Steilberg, architect, consultant to the University of California. The 

assistance of Mr. Steilberg and the University officials and their authorization to use 

the material furnished are gratefully acknowledged.

ICivil Engineer, Lennert and Associates, soils engineers, Oakland, Calif.
TECTONIC CREEP IN THE HAYWARD FAULT ZONE, CALIFORNIA

EXPLANATION

10 i i i i i

Stadium culvert 

Showing stations 100 feet apart

15

I I l_:_J I

Bypass culvert

Showing stations 100 feet apart

Active fault or shear zone 

within the Hayward fault 

zone (after Louderback, unpublished data) 0 100 200 300 4OO 500 FEET

Figure 3. Location of University of California Memorial Stadium, Berkeley, Calif.; fault or shear zone within the Hayward fault zone

(stippled); two Strawberry Creek culverts, with station designations on culverts; and location of major cracking of stadium culvert.

The part of the Strawberry Creek stadium 

culvert which lies under the Memorial Stadium was constructed in 1923, as part of the 

stadium contract. It is a cast-in-place concrete box culvert 4 feet wide that ranges 

from 3 feet 9 inches to 4 feet in height. The 

original culvert extended only from what is 

now the Corporation Yard to a point under 

the present KLeeberger Field. Other sections 

were added later.

Minor cracks in the culvert were noted 

when it was first inspected in 1932. Complete records of repair at that time are not 

available, but it is assumed that some repairs were made. In 1948 the culvert was 

again inspected and was found to be in very 

poor condition. In addition to leaky construction joints, holes in the floor (invert), and 

minor cracking, two large cracks were observed at stations 12+51.5 and 12+57 (fig. 3).

The large cracks were not those mentioned 

in the 1932 inspection report; they were described as being 1 inch wide completely 

around the culvert. A notation that the cracks 

might be due to movement along the Hayward 

fault zone was made by Walter T. Steilberg 

on a 1948 construction drawing. Repairs 

consisted primarily of grouting and installation of mine screwjacks as temporary shores 

in two parts of the culvert between stations 

10+50 and 13+00, and between stations 16+50 

and 17+50. The two large cracks were filled 

with mortar.

In 1954 the culvert was again inspected 

before making more permanent repairs. According to Walter T. Steilberg (oral commun., 

1965), the cracks at stations 12+51.5 and 

12+57 had widened between 1948 and 1954. 

At this time much of the floor of the culvert 

was paved, and 40 gunite rings, 41 inches
DAMAGE TO CULVERT UNDER MEMORIAL STADIUM UNIVERSITY OF CALIFORNIA, BERKELEY

long and 36 inches in inside diameter, were 

installed to replace the screwjacks. The 

large transverse cracks were repaired with 

gunite, but no details are available regarding 

their exact width at the time or the precise 

nature of the repairs.

When the culvert was inspected in 1965, the 

damage consisted of some leaky, construction 

joints; erosion of the invert; hairline cracks 

on the northeast side of the culvert at approximately stations 8+45, 9+25, and 10+70 

and between stations 14+27 and 15+80; and 

two major cracks at approximately stations 

12+50 and 12+55. There is no doubt that the 

latter two cracks are the same as those previously recorded at stations 12+51.5 and 

12+57.

The northwest (downstream) major crack, 

at about station 12+50, trends approximately 

at right angles to the culvert walls; in 1965 

it had a maximum width of 1-1/4 inches in 

the floor and a maximum width of 3-1/2 

inches on the northeast side of the ceiling, 

between the centerline and the junction with 

the wall. The southeastern (upstream) crack, 

which has a sinuous trend across the floor, 

showed a maximum gap of a quarter of an 

inch in the floor and a maximum width of 

2-3/4 inches on the southwest side of the 

wall. No lateral or vertical displacement of 

the cracks was apparent; the slight left-lateral off set reported in 1948 could not be confirmed. Water was pouring from the ceiling 

at both cracks, and the sides of the cracks 

and the walls near the cracks were coated 

with iron-stained calcium-carbonate, undoubtedly deposited by water entering the 

culvert through the cracks.

It can be assumed that the cracking of the 

floor has taken place since the floor was 

paved in 1954. The total average widening of 

the two cracks in the floor has been about 

1.25 inches in 11 years, approximately 0.11 

inch per year.

The main area of cracking and repair 

stations 10+50 to 13+00 is thought to lie 

within an active sheared band or fault which 

is part of the Hayward fault zone (G. D. 

Louderback, unpub. data). The general trend 

of the fault probably crosses the culvert at 

an angle of about 20°. Right-lateral movement along this fault has taken place, as evidenced by the offsetting of Strawberry Creek. 

Right-lateral movement along the active 

zone would exert tension on the culvert, and 

tension cracks would be expected in the

walls of the culvert. The formation and constant widening of the cracks that have been 

observed have probably resulted from such 

tensile stresses, and do not provide a direct 

measure of total movement on the fault since 

the culvert was installed.

No measurable lateral or vertical displacement of the cracks was observed, but 

the culvert appears to be slightly deflected 

laterally in the area of the two major cracks 

(fig. 4). Detailed measurements have not 

yet been made.

The Strawberry Creek bypass culvert, 

which carries part of the waters of Strawberry Creek north of the stadium, was constructed in 1954. G. D. Louderback (unpub. 

data), who was a consulting geologist for the 

architect in charge of construction, was of 

the opinion that two main faults or branches 

of the Hayward fault zone extend northwest 

across the campus, one lying under the stadium, and the other perhaps 400 to 500 feet 

farther west. He recommended that the section of the bypass culvert which would cross 

the easternmost fault be made of precast 

sections 4 feet in length, rather than the 8- 

foot sections used for the rest of the culvert. 

According to Walter T. Steilberg, architect 

(oral commun., 1965), weak mortar was used 

between the 4-foot sections, so that any failure in this area would take place along the 

joints rather than damaging the pipe sections. Construction plans show that the 4- 

foot sections were installed from station 

7+96 to station 15+50, as given on figure 3, 

or a distance of 754 feet.

General trendof fault

Figure 4. General relationship of fault to damaged culvert under 

the University of California Memorial Stadium, relative direction of movement of opposite sides of fault, and nature of 

damage to culvert (not to scale).
TECTONIC CREEP IN THE HAYWARD FAULT ZONE, CALIFORNIA

When the culvert was inspected in 1965, 

minor cracking was observed in many joints 

throughout the length of the culvert. The 

most pronounced and numerous cracks, some 

as much as one-eighth of an inch wide, were 

between stations 8+00 and 9+00, and between 

stations 10+80 and 12+80. The localities lie 

within the area thought to be crossing the 

active part of the fault. It is also in a place 

where the culvert slopes steeply, and all 

or part of the cracking in this area could 

be due to downslope movement of the 

pipe.

Maintenance personnel of the university 

report recurrent trouble with utilities, such 

as bending or breaking of conduit, on the 

rimway road near the playfield north of the 

stadium; the exact location is unknown at 

present.

Although the cracks in the stadium culvert 

could be due to a number of causes, such as 

weight of overlying fill or downslope creep 

of fill, it seems more probable that they are 

due to movement along a fault or belt of 

shearing within the Hayward fault zone. The 

major cracking of the stadium culvert, the 

most extensive cracking of joints of the bypass culvert, and the location of reported 

difficulties with utilities all lie in a northwest-trending band that is coincident with 

the probable location of the fault.

Since the stadium culvert was installed, 

there has been one earthquake (in 1937) severe enough to crack walls and fell chimneys 

in the Berkeley area, as well as numerous 

lesser shocks (Byerly, 1951). None of them 

were accompanied by any visible surface 

rupture. Damage to the culverts is therefore probably due to slow movement or 

creep along the fault, with the possible exception of a small sudden movement in 1937. 

Records show that widening of the tension 

cracks in the stadium culvert has been constant, although we do not know whether it 

has been continuous or in small increments. 

Moreover, it is not possible to tell whether 

movement has been along one plane or distributed in a wide zone.

Preliminary observations indicate that the 

stadium culvert has been slightly offset in a 

right-lateral direction. This apparent rightlateral deflection is consistent with direction 

of creep noted elsewhere on the fault.

CRACKS IN THE CLAREMONT WATER TUNNEL

BY F. B. BLANCHARD2 AND G. L. LAVERTY 3

Three circumferential cracks in the monolithic reinforced concrete lining of the 

Clare mont water tunnel, each exhibiting 

right-lateral displacement, where observed 

on December 1, 1964, at a point about 900 

feet from the west portal of the tunnel. The 

cracks occurred about 8 feet apart in a 16- 

foot section and each showed a horizontal 

displacement estimated to be about threefourths of an inch. The westerly crack had 

slime in it and appeared to be older than the 

other two.

The tunnel, constructed in the 1920*s, was 

last inspected in 1950, when no cracks were 

observed at this point. The location of the 

cracks was determined by pacing from the 

portal and is not precise. On the basis of 

the paced distance, the map-scaled location 

is lat 37°51'18"N., long 122°14'08"W., close 

to or within the area usually designated as 

the Hayward fault zone. At this point the 

tunnel is approximately 150 feet beneath the 

surface of the ground.

The Claremont water tunnel has a 9-foot 

horseshoe section and is one of five major 

facilities in the water system of the East 

Bay Municipal Utility District taking water 

from the east side of the Berkeley Hills to 

Berkeley, Oakland, and other cities on the 

east side of San Francisco Bay. After the 

December 1964 inspection, the tunnel was 

immediately refilled and placed back in service. Another inspection is planned for the 

winter of 1965-66.

DEFORMATION OF RAILROAD TRACKS IN 

FREMONT, CALIFORNIA

BY M. G. BONILLA

Six sets of railroad tracks in the Niles 

district of Fremont have been bent and 

shifted laterally by creep along the Hayward 

fault. The location of the tracks is shown on 

figure 2 (loc. C) and on figure 5.

The distortion of the railroad tracks was 

found by the writer in March 1965 during

2Manager, Water Resources and Planning Division, East Bay 

Municipal Utility District, Oakland, Calif.

sSupervising Sanitary Engineer, East Bay Municipal Utility 

District, Oakland, Calif.
DEFORMATION OF RAILROAD TRACKS IN FREMONT. CALIFORNIA

SOUTHERN PACIFIC

ipal defor«ation (within 

of Western Pacific and Southern 

Pacific railroad track in Fremont.

Figure 6. -Deformation of Southern Pacific siding by creep on th. 

Hayward fault. A. View westward; note new warehouse on

SP I/

geologic mapping of a segment of the Hayward fault zone coincident with his examination of geologic evidence for recent and continuing movement along the fault. This research was supported in part by the U S 

Atomic Energy Commission.

Surface expression of the Hayward fault 

on the low alluvial fan upon which the tracks 

are built consists of linear depressions 

scarps, and tonal differences in the soil visible on aerial photographs. Below the surface the fault forms an impermeable zone 

which results in a much higher ground-water 

level on the east side of the fault than on the 

west side, as indicated by wells close to 

both sides of the fault zone (Clark 1915) 

Use of these criteria indicated, within narrow limits, the active part of the Hayward 

iault zone and therefore where the railroad 

tracks should be deformed if creep were occurring along that part of the fault. Upon 

examination, the Southern Pacific main-line 

track was found to have a small deflection 

where the projected trend of this active zone 

crosses it and the parallel siding to have a 

large deflection (fig. 6). On finding this, the 

Western Pacific Railroad tracks about 500 

feet to the north were immediately examined, 

and they too were found to be deformed (fig 

7) along the same trend and in the same 

sense (right-lateral). Projecting the fault 

southeastward and using the same geologic 

criteria, the writer independently discovered 

the deformed warehouse in the Irvington district; the writer was not aware that the 

warehouse had been observed earlier bv 

Cluff. J

The tracks are deformed in a zone several 

hundred feet wide, but the major part of the
TECTONIC CREEP IN THE HAYWARD FAULT ZONE, CALIFORNIA

Figure 7. View westward along Western Pacific tracks showing 

deformation of rails (center of photo.) by creep on the Hayward fault. Curve in tracks on right side is not the result of 

creep.

deformation is in a narrower zone (stippled 

on fig. 5). The deformation is moderately 

sharp on the sidings and yard tracks (figs. 6 

and 7) but is smooth and difficult to see on 

the main-line tracks, owing to more frequent 

maintenance and heavier and faster traffic 

that tends to remove irregularities. The 

sharpest bends show a lateral shift of about 

4 inches in 70 feet (fig. 6) and 6 inches in 60 

feet (fig. 7). No vertical movement has been 

detected.

The rate of movement is evidently variable. The main-line Southern Pacific and 

Western Pacific tracks, first laid about 55 

years ago, both show a total shift of about 8 

inches, or an average rate of shift of more 

than 0.14 inches per year. The rate must 

vary greatly, however, as lateral shifts of 

as much as 1-1/2 inches within a period of 2 

or 3 days were reported by D. J. Laughlin 

(Western Pacific Railroad, oral commun., 

1965), who said that the rapid movements 

apparently do not coincide with local earthquakes.

The warehouse just north of the Southern 

Pacific tracks, shown on the map (fig. 5) and 

on the right side of figure 6A, was completed 

in 1964. No deformation resulting from creep 

was visible in March 1965.

CREEP IN THE IRVINGTON DISTRICT, 

FREMONT, CALIFORNIA

BY LLOYD S. CLUFF4 AND KARL V. STEINBRUGGE 5

Evidence for fault creep has been found 

along a 3-mile section of the active Hayward

4Chief Engineering Geologist, V. oodward-Clyde-Sherard and 

Associates, Oakland, Calif.

Structural Engineer, Pacific Fire Rating Bureau, San Francisco, Calif.

fault zone in the Irvington district Fremont, 

Calif.

Damage to a one-story storage building 

and to at least one offset fence astride the 

Hayward fault zone in the Irvington district 

of Fremont indicates that at least 6 inches of 

right-lateral movement has occurred on the 

fault within the last 44 years.

This paper presents only partial information on the 3-mile section from Alameda 

Creek south to Washington Boulevard in the 

Irvington district and discusses mainly a 

building that shows distinct evidence of 

right-lateral movement. A more detailed 

account of these studies will be presented in 

a forthcoming issue of the Bulletin of the 

Seismological Society of America.

Topographically, the area in the vicinity of 

the damaged storage building is relatively 

flat land on which the traces of faults in the 

Hayward fault zone are marked by fault 

scarps ranging from 3 to approximately 30 

feet in height, shallow depressions that form 

linear troughs 200 to 300 feet wide and 5 to 

10 feet deep, and sag ponds (figs. 8 and 9). 

These features are considered to be the result of successive movements along the fault 

during geologic and historic times.

Geologically, the building is near the outer 

limits of a broad alluvial fan, the Niles cone, 

which has been deposited by Alameda Creek 

between San Francisco Bay and the hills bordering the bay on the east. The fan is composed of layered deposits of gravel, sand, 

silt, and clay. The Hayward fault zone cuts 

through the alluvial deposits, and in places 

clay gouge formed along fault planes has 

created a ground-water barrier which produces different water levels on either side of 

the fault (Clark, 1915; Forbes, 1949).

During the course of geologic field mapping along the Hayward fault in November 

1960, the senior author discovered a damaged 

one-story storage building extending partly 

into the fault zone. A detailed inspection of 

the building showed that the damage was 

concentrated in the part of the building which 

lies along the northwest-trending fault zone 

and consisted of fractures, cracks, deflections, bends, and offsets, all of which indicated right-lateral movement. In checking 

the seismic history of the Fremont area, it 

was found that no earthquakes were recorded 

which appeared to have a magnitude strong 

enough to produce ground breakage along
CREEP IN THE IRVINGTON DISTRICT. FREMONT, CALIFORNIA

Figure 8. View looking southeast along strike of the Hayward fault zone near Lrvington district, Fremont, Calif.

the Hayward fault zone during the lifetime of 

this building. Local residents have no knowledge of earthquakes associated with fault 

movement since 1868.

The main building (fig. 10) was erected in 

1921, according to local residents. The building has nonreinforced concrete walls, a wood 

roof, and a concrete floor slab most of which 

is on grade. Most of the main building is on 

the southwest side of the Hayward fault zone 

which trends northwest through the northeast 

part of the main building (fig. 10).

The floor slab in the northeast part of the 

main building, having a floor area of about 60

by 200 feet, has been cracked and offset along 

a crack so that the northeast part of the slab 

appears to have moved 6 inches to the southeast with respect to the southwest part (fig. 

11). The exterior walls, which are 10 inches 

thick, have been bent, broken, and offset 

(fig. 12); the interior and exterior columns 

are as much as 6 inches out of plumb (fig. 11); 

and the roof has bowed right laterally.

Another part of the building extending into 

the fault zone has a buckled basement floor 

slab and a buckled basement wall.

The damage to this storage building is remarkably similar to the damage at the winery
10 TECTONIC CREEP IN THE HAYWARD FAULT ZONE. CALIFORNIA

Figure 9. View looking southeast along strike of Hayward fault, showing sag pond along the trace of the fault and a building extending into

the fault zone.

straddling the active San Andreas fault near 

Hollister, Calif., which is being damaged by 

fault creep (Steinbrugge and others, 1960). 

The ^similarity of damage and the fact that 

both structures are astride .traces of active 

faults suggest that fault creep was responsible for the structural damage to the building 

on the Hayward fault.

All the offsets and damage, when plotted 

on a map (fig. 10), aline parallel to the northwest strike of the Hayward fault and are 

within the fault zone. This damage appears 

to be limited to a band less than 10 feet wide 

and may indicate movement on a single fault 

plane within the Hayward fault zone; however, the width of the disturbed band may be 

wider. The rate of creep appears to be 6 

inches in 44 years. A more complete answer 

will not be known until detailed studies are 

made.

In March 1965 the authors installed creep 

reference marks inside the damaged building across the displaced zone in the floor 

slab so that a record of further movements 

could be made. For the time being, this 

measurement system is being used to note

any further creep movement along the fault. 

Work is in progress under the direction of 

the authors for permanent survey stations 

across the Hayward fault zone in the Irvington area.

The Hayward fault is under continuing 

study by the authors for several miles on 

each side of the damaged building. Additional evidence of movement has been observed by the authors on offset fences immediately to the north and approximately 1 

mile to the northwest of the damaged building. Reference structures, such as railroads 

southeast of the building and large-diameter 

pipelines, cross the fault zone at various 

nearby locations. These are being observed 

and surveyed by the authors in hopes of obtaining additional information as to the details of this fault movement. The evidence 

to date suggests that most of the creep observed along the Hayward fault zone in the 

Irvington district (in the amount of approximately 6 in.) occurred during the period 1951 

to 1957. Judging from possible effects on 

structures described in this report by Cluff 

and Steinbrugge, no measurable creep has 

occurred in this area since 1957.
CREEP IN THE IRVINGTON DISTRICT, FREMONT, CALIFORNIA 11

Strike of the Hayward Fault \ 

projected through the right 

lateral offsets in floors, 

walls, and fence

Figure 10. General configurations of damaged building and 

nearby offset fence.

In summary, it may be concluded that:

1. Damage to a one-story building on the 

Hayward fault zone in the Irvington district 

of Fremont indicates that at least 6 inches of 

right-lateral creep has occurred on the fault 

zone since construction in 1921.

2. Any structure astride an active fault is 

not only subject to damage resulting from 

sudden faulting associated with a severe 

earthquake, but may be damaged by a slow 

shearing movement along the fault.

3. Creep along an active fault is not cause 

for sudden alarm for it progresses slowly. 

However, because creep is irresistible and 

can be expected to continue, its location and

-Figure 11. View looking northeast and almost perpendicular to 

strike of fault inside building straddling fault. Construction 

joint in floor slab has been displaced approximately 6 inches 

right laterally.

rate of movement should be under constant 

observation.

4. The significant lesson to learn is that 

active faults should be recognized and respected in planning of future structures, developments, and communities.

Some questions yet unanswered with respect to the time-history of the creep phenomenon are as follows:

Is the creep occurring unnoticed in short, 

sporadic movements associated with earthquakes ?
12 TECTONIC CREEP IN THE HAYWARD FAULT ZONE. CALIFORNIA

Figure 12. View looking west and nearly perpendicular to fault 

along inside south wall of building.

Is the creep occurring along parallel or 

en echelon lines of slippage ?

What are the variations of creep along tne 

entire length of the Hayward fault?

Does the creep indicate an accumulation of 

regional strain, building up to a strong earthquake in the near future, or does the creep 

indicate a release of accumulating regional 

strain indicating that a strong earthquake 

should not be expected in the near future?

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* U. S. GOVERNMENT PRINTING OFFICE: 1969 O - 370-316