Report: San Andreas due to rupture in 2 spots

August 20, 2010 8:02:53 PM PDT
A new report came out Friday that reminds Californians that the state is overdue for a big earthquake along the San Andreas Fault and that adds to the prediction that the Bay Area are also overdue for big quake on the Hayward Fault.

The pen is always running, tracing squiggly lines across a drum in the seismology lab at U.C. Berkeley. And if we thought the "big one" was overdue before, now the big one just became two.

"One of the basic geologic principles is, if it happened in the past, it can happen again," says UC Berkeley seismologist Dr. Peggy Hellweg, PhD.

Until Friday, Hellweg was one of the few people in this world who could point out the Carrizo Plain, near Fort Tejon in Southern California.

We already knew that in 1857 the San Andreas Fault ruptured there and ruptured big. Friday, a new report came out showing that it ruptures regularly and repeatedly.

"The average for this study that was just published is 88 years and now it's been 150 some," says Hellweg.

And when it strikes, that earthquake will hit Southern California as high as a measure 7.9 -- much stronger than our own Loma Prieta. That will cause widespread damage, mayhem, and probably deaths.

"The rupture actually would not hit Los Angeles, but there would be a lot of shaking, a whole lot of shaking. We would feel it here, too in the Bay Area," says Hellweg.

But this latest research brings no reason for Northern California to feel more secure. In the East Bay, the Hayward fault is long overdue and could go at any time and the San Andreas Fault in Southern California is much the same as the San Andreas Fault in the north.

"Remember we had a very large earthquake in 1838, but that ruptured only a short segment that broke again in 1906. We see hints of that pattern, as well," says Berkeley Seismologist Roland Burgmann, Ph.D.

Or, to put it more bluntly that so-called stable ground beneath our feet is really just an illusion. In the broader time frame has never stopped moving.


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