Researchers find up to 70 percent chance of a big quake in southern California in next 30 years

The San Andreas fault is one of the most dangerous seismically active faults in the world, due to its proximity to densely populated regions of California. But how often does this fault rupture and cause a large earthquake? About every 200 years, which is coming up soon, according to an article to be published in the May 13 issue of the journal, Science.

Glenn Biasi, research assistant professor with the University of Nevada, Reno's Nevada Seismological Laboratory and colleagues from the University of Oregon and the U.S. Geological Survey developed new methods of linking distributed evidence of prehistoric earthquakes to calculate the probability that the San Andreas fault will rupture again within the next 30 years.

Three different rupture scenario models are consistent with present data. Depending on the model, the scientists have determined that there is a 20 percent to 70 percent chance that a large quake will shake southern California – "either a single long rupture or a series of overlapping ruptures in a short time interval" – within the next 30 years, according to the article, "Past and Future Earthquakes on the San Andreas Fault."

For a copy of the article, contact the American Association for the Advancement of Science Office of Public Programs: +1-202-326-6440 or scipak@aaas.org.

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