UCLA EXPERT PREDICTS SAN ANDREAS RUPTURING.

Byline: Troy Anderson Staff Writer

Earthquake experts and geophysicists said Friday that they are taking seriously a prediction that a magnitude-6.4 or greater earthquake will take place along the southern San Andreas Fault by Sept. 5.

The prediction of UCLA seismologist and mathematical geophysicist Vladimir Keilis-Borok, who is known to colleagues as a ``big shot in our field,'' is viewed as credible because last June his team predicted the magnitude-6.5 San Simeon Earthquake that occurred Dec. 22 and the magnitude-8.1 Hokkaido, Japan, earthquake of Sept. 25.

``It's raising a few eyebrows among earthquake researchers,'' said Ken Hudnut, geophysicist at the U.S. Geological Survey at Caltech in Pasadena. ``This is a section of the San Andreas that we've known for years is among the most hazardous.''

A 1998 report stated that in the next 30 years, there is a 40 percent probability of a major quake on that section of the San Andreas.

``Since the 1980s, it's been recognized as the potential source of the future 'Big One' on the San Andreas,'' Hudnut said.

Hudnut said part of the San Andreas Fault near Palm Springs is believed to be capable of an 8.0 earthquake, and if it occurred it could rupture all the way to the city of San Bernardino. If that happened, it could trigger earthquakes larger than the magnitude-6.7 Northridge Earthquake.

``It could trigger either simultaneous slips on other faults or delayed triggering of earthquakes on other faults,'' Hudnut said. ``The Sierra Madre Fault system goes out from the San Fernando Valley and if that fault ruptured, it would be a 7.5-magnitude earthquake. It would be more of a direct hit on the San Gabriel Valley.''

Hudnut said a magnitude-8.0 earthquake on the southern portion of the San Andreas alone would produce a lot of strong shaking in the Los Angeles area and rattle downtown skyscrapers very hard because of slower-motion shaking.

But Thomas H. Jordan, director of the Southern California Earthquake Center, said experts don't know enough about earthquake prediction to confirm whether Keilis-Borok's prediction is valid.

``So they are sort of placing a bet that an earthquake will occur,'' Jordan said. ``We really don't know the probability, and in fact the probability may be small. We should think of this type of prediction as being an experimental technique, one that is under testing.''

Jordan said that portion of the San Andreas is an area scientists believe is ``primed to rupture sometime.''

``It might be the date they predict, or it might be 10 years from now or even much longer than that,'' Jordan said.

Keilis-Borok said his team has made a major breakthrough in earthquake prediction by discovering the possibility of making predictions months ahead of time, instead of years, as in previously known methods.

``Earthquake prediction is called the Holy Grail of earthquake science, and has been considered impossible by many scientists,'' said Keilis-Borok, a professor in residence at UCLA's Institute of Geophysics and Planetary Physics. ``This discovery was not generated by an instant inspiration, but culminates 20 years of multinational, interdisciplinary collaboration by a team of scientists from Russia, the United States, Western Europe, Japan and Canada.''

The team includes experts in pattern recognition, geodynamics, seismology, chaos theory, statistical physics and public safety. They have developed algorithms to detect precursory earthquake patterns.

Prediction by this method is based on observations of small earthquakes that occur daily. Scientists study the chains of small earthquakes, then look back in history to see whether they were preceded by other seismic patterns, Keilis-Borok said.

One of the challenges in earthquake prediction has been to achieve a high proportion of successful predictions, while minimizing false alarms.

The team's current predictions have not missed any earthquake, and have had its two most recent ones come to pass.

The good news is that Hudnut doesn't expect Southern California to fall off into the sea.

``It's conceivable in little places here and there in some future earthquake that we might have land areas drop down below sea level, but considering the region we are in, this myth of California falling off into the sea is wishful thinking on the part of people in Las Vegas who want oceanfront property.''

Troy Anderson, [phone]

troy.anderson(at)dailynews.com

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SOURCE: American Red Cross 

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