Understanding Earthquake Hazards in the San Francisco Bay Region

The Hayward Fault—Is It Due for a Repeat of the Powerful 

1868 Earthquake?

On October 21, 1868, a magnitude 6.8 earthquake struck the San Francisco Bay area. Although the region was 

sparsely populated, the quake on the Hayward Fault was one of the most destructive in California’s history. U.S. Geological 

Survey (USGS) studies show that similar 

Hayward Fault quakes have repeatedly 

jolted the region in the past and that the 

fault may be ready to produce another 

magnitude 6.8 to 7.0 earthquake. Such an 

earthquake could unexpectedly change 

people’s lives and impact the Bay Area’s 

infrastructure and economy, but updated 

building codes and retrofits, as well as 

planning, community training, and preparedness, will help reduce the effects of 

a future Hayward Fault earthquake.

Strong shaking 

during the 1868 

Hayward Fault 

earthquake caused 

the second story of 

the Alameda County 

Courthouse in San 

Leandro to collapse (photo courtesy of the Bancroft Library, University of California). The inset 

photo shows the courthouse before the quake (photo courtesy of San Leandro Public Library). 

The 1868 earthquake devastated several East Bay towns and caused widespread damage in 

the San Francisco Bay region.

In the early morning of October 21, 

1868, seismic waves from a powerful earthquake raced through the fogshrouded San Francisco Bay area. 

Frightened people ran out of their homes, 

and cattle and even fire-engine horses 

panicked and bolted. Strong shaking 

lasted more than 40 seconds, devastating 

several East Bay towns. Brick buildings, walls, and chimneys were also 

shaken down in Oakland, San Francisco, 

Santa Rosa, and San Jose, and there was 

serious damage in Napa and Hollister. Numerous witnesses reported seeing the ground 

move in waves. Shaking was felt as far away 

as Nevada, and aftershocks rattled the Bay 

Area for weeks. Even though the region was 

only sparsely populated at the time, the 1868 

quake killed about 30 people and caused great 

property damage. It still ranks as one of the 

most destructive earthquakes in California’s 

history, but this is not the end of the story. The 

Hayward Fault will rupture violently again, 

and perhaps soon.

Stadium

Hamilton

Gulch

0 500

0 100 200 300 METERS

1,000 FEET

N

A filtered vertical laser image, taken using a technique called light detection and ranging (LIDAR), of part of the 

Hayward Fault (red lines) in the City of Berkeley. The fault passes through the University of California Berkeley football 

stadium (left), and past earthquake movements have significantly offset Hamilton Gulch (center). Arrows show relative 

movement on the fault.

1868

Napa

Santa

Rosa

0 20 MILES

N

Major faults

AREA

OF MAP

CALIF

Oakland

San Leandro

San Jose

Fremont

Hayward

San 

Francisco

80

101

SAN GREGORIO

RODGERS

CREEK

CALAVERAS

SAN ANDREAS

Hollister

HAYWARD

Major earthquake faults 

in the San Francisco 

Bay region. The section 

of the Hayward Fault 

that produced the 1868 

Hayward earthquake is 

highlighted in yellow. Dot 

size indicates the present 

relative population sizes 

of cities.

U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2018–3052, August 2018

Supersedes Fact Sheet 2008–3019
The Hayward Fault is Creeping

The Hayward Fault is a near-vertical surface that allows two huge blocks 

of bedrock to move past each other in the eastern San Francisco Bay region. 

It is one of a number of “creeping” earthquake faults in the region, meaning the 

two sides of the fault are constantly moving past each other at a slow rate. Ample 

evidence for the creep of the fault is provided by roads, curbs, and buildings that are 

being progressively offset. U.S. Geological Survey and other scientists have shown 

that the rate of movement is about 1/5 inch (5 millimeters) per year. Creep generally appears to be limited to the topmost 3 miles (5 km) of a fault plane, and below 

that depth, the fault is locked and building up stress. Creep and small earthquakes 

account for only about one-third of the long-term (thousands of years) movement on 

the Hayward Fault, and the remaining two-thirds must be released in large earthquakes like the 1868 event.

Scientists at the University of 

California, Berkeley, are using 

a technique called interferometric satellite aperture radar 

(InSAR), which uses repeat 

satellite radar surveys of the 

Earth’s surface to monitor 

creep along the Hayward 

Fault. Comparing radar returns 

from the same points on the 

ground over time reveals 

how rapidly the points are 

moving. This technique allows 

scientists to determine which 

parts of a fault are creeping 

and at what rates, and which 

parts are locked all the way 

to the surface and thus may 

be capable of producing even 

stronger quakes.

Creep (slow, steady movement) on the 

Hayward Fault has offset this curb in the 

city of Hayward.

0

0 1 2 3 KILOMETERS

1 2 3 MILES

HAYWARD FAULT

Fremont

N

0

Millimeters per year

–10 10

Interferometric satellite 

aperture radar, or InSAR, 

uses repeated passes 

by satellites to record 

the change in distance 

between the satellite and 

recognizable points on the 

ground (dots). This InSAR 

image of part of the East 

Bay clearly shows creep 

on the Hayward Fault. In 

general, warm colors mean 

the points are moving to 

the southeast (closer to the 

satellite), and cool colors 

mean the points are moving 

to the northwest (farther 

away). The color scale 

indicates the rate of this 

movement in millimeters 

per year (1 millimeter = 

0.04 inch).

The Earthquake of 1868

The 1868 earthquake on the Hayward 

Fault capped a decade-long sequence of 

seven increasingly strong quakes in the 

Bay Area. Ground cracking caused by this 

earthquake was traced for 20 miles along 

the Hayward Fault, from Warm Springs 

in Fremont north to San Leandro. Historical land-survey data suggest that the fault 

broke as far north as Berkeley, with an 

average horizontal offset of about 6 feet 

(2 meters).

Shaking from the 1868 quake was the 

strongest that the new towns and growing 

cities of the Bay Area had ever experienced. Until it was eclipsed by the great 

1906 earthquake, the 1868 earthquake 

was known as the “great San Francisco 

quake.” The area of strongest shaking 

covered about 1,000 square miles. In San 

Francisco, the largest city on the west 

coast with a population of 150,000, five 

people were killed and property losses 

were significant. Many brick walls, 

cornices, and other heavy architectural 

elements of buildings in the city fell, 

and the U.S. Custom House and several 

other structures built on land reclaimed 

from the former Yerba Buena Cove 

(today’s Financial District) sustained 

severe damage. However, as in 1906, 

well-constructed buildings on firm ground 

sustained much less damage.

Towns in the East Bay suffered the 

most severe damage. Almost every building in Hayward, then a town with about 

500 residents, was wrecked or severely 

damaged—few places have paid so dearly 

to have a fault named after them. At San 

Leandro, with a population of about 400, 

the second floor of the Alameda County 

Courthouse collapsed, and many other 

buildings were destroyed. At Mission 

San Jose, in southern Fremont, the 

adobe church built in 1809 and other 

mission buildings were heavily damaged. 

Oakland, a town of about 12,000 and 

mainly wood-frame buildings, was much 

less heavily damaged than San Leandro 

and Hayward. San Jose, a town of about 

9,000 that lies several miles south and 

west of the fault trace, had few wrecked 

buildings but many fallen chimneys.

Understanding the 1868 Quake

Because seismographs had not yet 

been invented, there are no recordings 

of the 1868 earthquake. Much of what 

we know about the 1868 quake is documented in a chapter of an important report 

on the 1906 San Francisco earthquake, 

which was published in 1908. The chapter 

reviewed the descriptions of surface faulting, collected damage and felt reports, and 

interviewed survivors of the earthquake. 

USGS and other scientists have used 

the 1908 report, as well as historical 
Similarity to the 1995 Kobe Earthquake

Studies of past earthquakes allow scientists to forecast the effects of future quakes. A quake similar to 

the anticipated next large Hayward Fault earthquake 

may be the magnitude 6.9 earthquake that struck 

Kobe, Japan, in 1995. The geography of Kobe, a port 

city built along the Nojima Fault on Osaka Bay, is strikingly similar to that of the East Bay, and the Nojima 

and the Hayward Faults have similar lengths and 

types of movement. The 1995 Kobe quake and subsequent fires caused more than 5,000 deaths. Shaking 

and ground failures, including liquefaction (in which 

shaken sandy soils behave like a liquid and cannot 

support the weight of structures), devastated residences and infrastructure. Damage to the port facilities in Kobe resulted in a permanent loss of business, 

because some shipping companies relocated to other 

undamaged ports in Japan. Many lower income areas 

of Kobe were not rebuilt for more than a decade. 

Although construction codes and practices for 

residential buildings in Japan were not as stringent 

in 1995 as those now in use, and Kobe was not as 

prepared for earthquakes as the Bay Area is now, it is 

likely that a repeat of the 1868 Hayward earthquake will also produce 

significant loss of life and high levels of damage.

San Francisco

San Jose

Oakland

Fremont

Hayward

Richmond Concord

Kobe

Akashi

Osaka

Wakayama

Tokushima

Sumoto

Vallejo

Osaka Bay

San

Francisco

Bay 1868 Rupture

1995 Rupture

154 miles above

0 10 20 MILES

0 10 20 KILOMETERS

N

N

0 10 20 MILES

0 10 20 KILOMETERS

The urban geographic settings of the Nojima Fault of Kobe, Japan, and the 

Hayward Fault, California, are very similar, as were the lengths of rupture in their 

most recent strong earthquakes. The 1995 Kobe earthquake caused more than 

5,000 deaths and widespread devastation (satellite images from Google Earth).

newspaper accounts, photographs, pioneer 

diaries, and letters, to understand the 

shaking effects and gauge the size of the 

1868 earthquake. To estimate the shaking 

intensity, it is necessary to consider the 

construction of the damaged buildings, 

that is, whether they were adobe, brick, 

or wood. Combining these intensity 

estimates with current knowledge of 

earthquake effects and geology allows 

researchers to create a “ShakeMap” that 

depicts the inferred intensity of shaking 

throughout the region in 1868 and can 

also be used to predict damage to modern 

buildings. The map shows that shaking 

was strongest in Hayward, Fremont, and 

San Leandro, and weaker but damaging 

in Oakland, San Francisco, and San Jose. 

Scientists estimate that the magnitude of 

the 1868 quake was 6.8. Comparing the 

ShakeMaps from the 1868 Hayward and 

the 1989 (magnitude 6.9) Loma Prieta 

earthquakes shows that a repeat of the 

1868 quake would produce much higher 

levels of shaking and damage in the East 

Bay than the 1989 quake.

Impact of the 1868 Hayward Quake 

on Building Practice

After the 1868 quake, and a previous 

one in 1865, damaged San Francisco, 

engineers worked to strengthen buildings 

throughout the Bay Area. They retrofit 

masonry buildings with iron tie-rods and 

anchors between floors and walls, and 

they designed and implemented systems 

to make new buildings more resistant to 

shaking. Innovations included a stronger 

course of brick-laying, incorporating 

iron binders into brick walls, and interior 

iron framing. But the most significant 

improvement in shaking resistance was 

the advent of steel-frame buildings in 

1885. These measures combined to ensure 

that buildings built in San Francisco 

between 1868 and 1906 survived the 

powerful shaking of the 1906 San Francisco quake, with the exception of the San 

Francisco City Hall.

Pacific Ocean

Pacific Ocean

Oakland

Hayward

San Francisco

San

Jose

San

Mateo

Antioch

Benicia

Livermore

Palo

Alto

Berkeley

Walnut

Creek

San Leandro

Santa

Cruz

Oakland

Hayward

San Francisco

San

Jose

San

Mateo

Antioch

Benicia

Livermore

Palo

Alto

Berkeley

Walnut

Creek

San Leandro

Santa

Cruz

1868 1989

Fremont Fremont

N N

0 10 20 MILES

0 10 20 KILOMETERS

0 10 20 MILES

0 10 20 KILOMETERS

Epicenter of

Very light 1989 quake

Very heavy

Moderate

Light

Heavy

Moderate/

Heavy

MMI Damage

V

VI

VII

VIII

IX

X+

A ShakeMap showing the inferred intensity of ground shaking in the 1868 earthquake (measured 

as MMI, or Modified Mercalli Intensity), compared to a ShakeMap for the 1989 magnitude 6.9 

Loma Prieta earthquake. Red lines are major earthquake faults; black line shows the portion of 

the Hayward Fault that ruptured in 1868; diamonds show locations of damage reports (1868) and 

seismic recordings (1989).
Other important engineering lessons 

from the 1868 earthquake, though actively 

discussed at the time, were not heeded. 

The hazard of building on landfill in San 

Francisco Bay (called “made land” at the 

time) and the admonition to “build no more 

cornices” were largely forgotten by the time 

of the 1906 quake.

Is the Hayward Fault the Nation’s 

Most Dangerous Fault?

Two factors combine to make the 

Hayward Fault very dangerous. The 

first is its location in the urban heart of 

the Bay Area. The Hayward Fault is the 

single most urbanized earthquake fault 

in the United States—in 1868 there 

were only 24,000 residents living in 

Alameda County; now there are more than 

2.4 million people. Hundreds of homes 

and other structures are built along the 

fault trace, and mass transit corridors, 

major freeways, and many roadways 

cross it at numerous locations. Also, 

critical regional gas and water pipelines 

and electrical transmission lines cross 

the fault. In 2018, the USGS released 

the HayWired earthquake scenario (see 

“More Information” box), which included 

updated forecasts of major impacts of a 

large earthquake on the Hayward Fault, 

including the loss of housing resulting 

from the shaking and fires caused by the 

quake and long-term outages of drinking 

water. Ongoing slip and aftershocks along 

the Hayward Fault may last for months, 

further damaging buildings and infrastructure that straddle the fault.

A second factor making the Hayward 

Fault so dangerous is that its most recent 

damaging earthquake was more than 

150 years ago. USGS scientists have found 

evidence for 12 quakes on the southern 

Hayward Fault during the past 1,900 years. 

Notably, the last six quakes (in 1134, 1317, 

1475, 1629, 1725, and 1868) occurred 

at intervals of 95 to 183 years, with an 

average interval of about 150 years. 

The Next Major Hayward Fault 

Earthquake

The 150th anniversary of the 1868 

quake was observed in 2018; scientists 

are convinced that the Hayward Fault 

has reached the point where a powerful, 

damaging earthquake can be expected at 

any time. According to a 1996 Earthquake 

Engineering Research Institute report, the 

next major Hayward Fault earthquake is 

expected to produce extensive damage to 

residences, businesses, and to transportation 

and public utility infrastructure. Several 

hundred thousand people are likely to be 

homeless after the quake. 

As demonstrated by the aftermath of 

Hurricanes Katrina, Sandy, and Maria, 

recovery from catastrophic events can 

take years. According to a 2013 study 

(see “More Information” box), a repeat 

of the 1868 earthquake could cause 

extensive economic losses (including 

damage to buildings and contents, business 

interruption, and living expenses) exceeding 

$100 billion, with 85 percent or more of 

both residential and commercial losses 

being uninsured. Damage to infrastructure, 

such as transportation and utilities, and 

other long-term economic effects could 

substantially increase the losses.

The 1868 Hayward Fault earthquake 

is a reminder of the tremendous power 

that lurks beneath the Earth’s surface in 

the San Francisco Bay region. Other large 

quakes, like the damaging 1995 Kobe 

earthquake in Japan, offer realistic visions 

of the destruction that such events can inflict 

in a densely populated urban region. The 

population at greatest risk from a Hayward 

Fault earthquake is 100 times greater than 

in 1868. The urban infrastructure in the Bay 

Area has been tested only by the relatively 

remote, 1989 magnitude 6.9 Loma Prieta 

earthquake, and the smaller 2014 magnitude 

6.0 South Napa earthquake. USGS 

earthquake science tells us that it’s now 

urgent to prepare for the next magnitude 

7 quake on the Hayward Fault. Preparing 

now can significantly reduce loss of life and 

property from that coming quake.

1200 1400 1600 1800 2000

158 97

Year

153 142 150 years and

1317 1475 1629 1725 1868 counting

Quakes

California

missions

founded

1906 

San Francisco

earthquake

Black

plague

in Europe

Magna

Carta

183

1134

Columbus

reaches

New World

Interval

(years)

Study of excavations across the Hayward Fault has provided a record of strong earthquakes, all 

estimated at magnitude of 6.3 or greater, going back hundreds of years—some historical events 

are shown for reference. The dates for earthquakes before 1868 are based on radiocarbon dating. 

Note that the interval between successive quakes has varied from 95 to 183 years, averaging 

150 years, and it is now more than 150 years since the 1868 earthquake.... 

More Information:

Magnitude 6.8 October 21, 1868, 

Hayward Fault Earthquake

http://earthquake.usgs.gov/regional/

nca/1868

The HayWired Earthquake Scenario—

We Can Outsmart Disaster: USGS 

Fact Sheet 2018–3016, at https://doi.

org/10.3133/fs20183016

The 1868 Hayward Earthquake: 

145-Year Retrospective, Risk 

Management Solutions, Inc. White 

Paper, at https://forms2.rms.com/

rs/729-DJX-565/images/eq_1868_

hayward_eq_retrospective.pdf

Putting Down Roots in Earthquake 

Country, USGS General Information 

Products 15, 41, and 42, at 

http://www.earthquakecountry.org/

booklets/.

Earthquake Country Alliance, 

Bay Area, https://www.

earthquakecountry.org/bayarea/

Thomas M. Brocher, Jack Boatwright, 

James J. Lienkaemper, Carol S. Prentice, 

David P. Schwartz, and Howard Bundock

Edited by Claire Landowski

Graphic design by Suzanne Roberts

Banner photograph of the Bay Bridge and 

San Francisco skyline by Scott Haefner.

Seismogram from 1906 San Francisco earthquake, 

courtesy of IRIS Data Management Center.

COOPERATING ORGANIZATIONS

Earthquake Country Alliance

University of California at Berkeley

https://twitter.com/USGS

https://www.facebook.com/USGeologicalSurvey

ISSN 2327-6916 (print)

ISSN 2327-6932 (online)

https://doi.org/10.3133/fs20183052

Supersedes USGS Fact Sheet 2008–3019