This scenario earthquake is for a magnitude 7.1 earthquake on the Peninsula segment of the San Andreas fault. There is a seventy percent chance of a big earthquake of this magnitude or greater occuring within the next thirty years.

An earthquake along the Peninsula segment of the San Andreas fault would cause a predicted housing loss of over 45,000 dwelling units. Of these uninhabitable units, 42% are predicted to be within San Francisco. Most of the rest of the total forecasted uninhabitable dwelling units are predicted to be in San Mateo (29%), Santa Clara (20%) and Alameda (7%) counties.

It is important to note that these numbers are higher in San Francisco than in the County of San Mateo, which is geographically closer to the fault line. Damage in San Francisco County is higher than that in San Mateo County by 46%. In San Francisco, almost 6% of the total housing stock is made uninhabitable versus just over 5% in San Mateo County. San Francisco's denser, older and more vulnerable housing types play a significant role in determining this damage pattern.

San Francisco County possesses the highest numbers of displaced and shelter populations. The high percentage of the total peak shelter population (45%) reflects the large percentage of uninhabitable units there (42%). However, because there are fewer number of individuals per dwelling unit in San Francisco County, its displaced population represents only 40% of the total. In addition to the impact of uninhabitable units, demographic factors such as
income and household type make inner city areas have the largest shelter needs, offsetting the effects of smaller household size in these areas.

The housing impacts of this earthquake are higher in San Francisco than in San Mateo County where the fault source of this earthquake is located. This discrepancy points to the role of housing type and demographic factors, particularly household income, in predicting peak shelter population.

The map above shows what the predicted magnitude of the "BIG" earthquake will be in certain areas. See if you can find you location in the bay are. Are you prepared for a major disater? Take a look at the safety precations webpage below.

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