Earthquake Hazard in the San Francisco Bay, California, Region
Given the recent interest in major earthquakes in the Pacific Northwest, it is interesting to re-examine the earthquake potential of the San Francisco Bay region. In particular, we examine the probability of earthquakes having magnitude M>6 and M>7 in the most populated region around San Francisco. The map below shows San Francisco bay, the latest WGCEP/UCERF2 earthquake fault map, and a rectangular selection region. The figure was produced using the polygon selection with the Hazard Viewer.
In the defined region, the probability of earthquakes of various magnitudes over several time interavals into the future from May 12, 2014 are shown in the table below.
We can also compute the forecast time series (chance of an earthquake as a function of time) for M>6 events:
It can be seen that the probabilities for these M>6 earthquakes are fairly small, averaging about 7%, and decreasing. Note, however, that even small probability events can occasionally happen. We can also compute the probabilties of larger events with M>7, which are also decreasing, and small:
The general decrease in probability with time is due to the relatively low rate of small earthquake activity in the region, combined with the occurrence of larger events in the California-Nevada-Pacific Northwest.
About OpenHazards Bloggers
Steven Ward is a Research Geophysicist at
the Institute of Geophysics and Planetary Physics, UC Santa Cruz. He specializes in the quantification and simulation of
natural hazards. Read Steve's blog.
John Rundle is a Distinguished Professor of Physics
and Geology at UC Davis and
the Executive Director of the APEC Collaboration for Earthquake Simulations. He
chaired the Board of Advisors for the Southern California Earthquake Center from 1994 to 1996. Read John's blog.
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