A forthcoming report that is about to be published in the scientific journal Geology quotes earthquake researchers as saying the next major earthquake along California’s San Andreas Fault could happen soon. University of California-Irvine seismologist Lisa Grant Ludwig.

UC Irvine and Arizona State University researchers charted earthquakes going back 700 years by digging trenches and taking charcoal samples. The research team found quakes have occurred on one portion of the fault – the Carrizo Plain – every 45 to 144 years, which is much more frequent than the widely accepted belief that an earthquake occurs every 250 to 400 years, and also more frequent than the 235-year average used in recent seismic hazard evaluations. Researchers said their findings concluded not all earthquakes were as strong as had been thought, but they still ranged between magnitude 6.6 and 7.9.

The last big quake on that part of the San Andreas fault happened 153 years ago – a 7.8 magnitude earthquake at Fort Tejon, Calif. It was one of the strongest earthquakes ever recorded in the United States, but only two people were killed because that area was largely unpopulated at that time. Mary Lou Zoback, vice president of earthquake risk applications for Risk Management Solutions (RMS) said the new likelihoods “are already incorporated in our models.”

Next Big California Earthquake Could Happen Soon (National Underwriter 8/23/10)

August 24, 2010