Earthquake Risk in the Bay Area:The Hayward Fault

Ellen Metzger

BAESI

March 23, 2013

Earthquakes in the Bay AreaCan We Predict Them?

• Science vs. pseudoscience• Short-term prediction vs. long-range forecasting.• Prediction vs. prevention

Long-Range Forcasting

• Based on knowledge of when and where past earthquakes have occurred.Paleoseismology – record of past offsets and recurrence interval Seismic gaps

The Hayward Fault

America’s Most Dangerous Fault?

A tectonic “time bomb”

Source: USGS

Forecasting (probability) vs. prediction

Bay Area EQ Probabilities

Hayward – Rodgers Creek Faults have the highest probabilities

Paleoseismology - the study of prehistoric earthquakes. 

http://www.tulane.edu/~sanelson/images/paleosseis.gif

http://pubs.usgs.gov/fs/1999/fs152-99/images/faults.jpg

http://1868alliance.org/images/photos

M7 1868 Hayward earthquake

• 30 fatalities, 5 in San Francisco (12th most lethal US earthquake)

• $350,000 (>$5-100M in 2007 dollars) in damage in San Francisco alone

• Extensive damage in San Leandro, Hayward, and Fremont (total population less than 2000)

• Bay Area population was 260,000 (it is now 27 times larger)Source: USGS

1868 HaywardEarthquake

(“The Great SF Earthquake”)

Source: USGS

38°

-121.5°

37.5°

-121°

Earthquake of M > 6.8 on the Hayward Fault?

A major earthquake today on the Hayward fault

• would impact more than 5 million people and

• Cause estimated total economic losses to residential and commercial properties would likely exceed $165 billion.

• Other factors, such as fire, damage to infrastructure and related disruption would substantially increase the loss

http://www.usgs.gov/newsroom/article.asp?ID=1899&from=rss

http://earthquake.usgs.gov/eqcenter/dyfi.php

Did You Feel It?