Earthquake Preparedness and Response

The towns of Portola Valley and Woodside sit directly on top of the San Andreas Fault.

Earthquakes in the San Francisco Bay Area result from strain energy constantly accumulating across the region because of the motion of the Pacific Plate relative to the North American Plate (Figure 1). The region experienced large and destructive earthquakes in 1838, 1868, 1906, and 1989, and future large earthquakes to relieve this continually accumulating strain are a certainty.earthquake map

High-res, printable version of this map

As experience has demonstrated from recent earthquakes in Northridge, California (M6.7, 1994, 20 killed, $20B in direct losses) and Kobe, Japan (M6.9, 1995, 5500 killed, $147B in direct losses), earthquakes of this size can have a profound impact on the social and economic fabric of densely urbanized areas.

The accompanying figure shows the updated probabilities for earthquakes of magnitude 6.7 or greater in the next 30 years. The overall probability of a magnitude 6.7 or greater earthquake in the Greater Bay Area is 63%, about 2 out of 3.

The probability of a large earthquake on the San Andreas Fault in the next 30 years is about 21%, or about 1 out of 5. This fault was responsible for the magnitude 7.8 1906 San Francisco earthquake and the magnitude 6.9 1989 Loma Prieta earthquake.

The earthquake probability is highest for the Hayward-Rodgers Creek Fault system, 31%, or nearly 1 out of 3. The last damaging earthquake on the Hayward Fault was in 1868. The 140+ years since 1868 is the same length of time as the average interval between the past 5 large earthquakes on the southern Hayward Fault.

The nearby San Gregorio Fault along the San Francisco Peninsula coast, has a probability of 6%, of producing a magnitude 6.7 or greater earthquake in the next 30 years.

View simulated shaking movies for past and predicted earthquakes in our area.

Putting Down Roots in Earthquake CountryClick image for handbook
Putting Down Roots in Earthquake Country: Your Handbook for the San Francisco Bay Region

Prepare your home and family for a major earthquake.

Learn how to respond during and after a major earthquake.

Get trained to be a part of your community's disaster response team.

Since 1991, CERPP, the fire district and the two towns have conducted an earthquake response exercise every year. The next earthquake exercise is scheduled in conjunction with the Great California Shake Out statewide earthquake exercise, on October 15th. For more information on local CERPP participation, click here. For information on past exercises click here.

 

Click the image below for a good earthquake preparedness document.

Earthquake Preparedness Flyer pdf link

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