Scientists: Possible earthquake pattern

Flagstaff Arizona Sun ^ | 01/11/2004 | AP

[Holly_P]

BERKELEY, Calif. (AP) -- Scientists believe they have detected a pattern in earthquakes occurring along the San Andreas Fault, a finding that eventually could help predict them. The study, by seismologists at the University of California, Berkeley, looked at small, recurring quakes along a section of the fault and found they tended to follow a three-year cycle. Meanwhile, the scientists found that larger quakes in the area studied tended to occur at the beginning of the cycle, when the small quake activity was on the upswing.

The research could be a key development in achieving more precision in forecasting, although scientists at Berkeley and elsewhere caution that more study is needed to see if the cycle continues or applies to other faults.

"It is a very interesting study. There's a lot, of course, that remains to be checked out," said Tom Jordan, director of the Southern California Earthquake Center.

"They may have detected the heartbeat of the San Andreas, but we don't know exactly what's going on. We don't understand the fundamental nature of that heartbeat."

Still, the research, published Friday in the journal Science, could help narrow earthquake probabilities. Now, probabilities are generally given over a 30-year period.

The study, which was coauthored by the late UC Berkeley seismologist Thomas V. McEvilly, covers 16 years of data from 1984 to 2000.

Scientists looked at a 110-mile section of the 800-mile San Andreas Fault, starting near Parkfield, about halfway between Los Angeles and San Francisco and one of the most seismically active regions in the world, and extending to Loma Prieta, near the city of Santa Cruz.

The 1989 Loma Prieta earthquake, the 7.1 temblor that struck the San Francisco region during the World Series, was one of the larger earthquakes that researchers found during the first year of the three-year cycles.

If the pattern continues, the next upswing in small quakes should occur later this year. However, Nadeau said that doesn't necessarily mean a big one's coming -- because scientists didn't find earthquakes close to the size of Loma Prieta in every three-year cycle

[Holly_P]

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[msdrby]

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[EggsAckley]

The 1989 Loma Prieta earthquake, the 7.1 temblor that struck the San Francisco region during the World Series, was one of the larger earthquakes that researchers found during the first year of the three-year cycles.

Arrgghh! I can attest to that!!

[aimhigh]

For years I've been waiting for someone to run the earthquakes through a computer and find patterns. It's logical.

[EuroFrog]

It is certainly a good idea. But, what would you do with the information? (Im just clueless so I have no idea.) Possibly knowing a 'big one' could hit in any certain year, Im just not sure what you could do except leave the area, not a possiblity for most of the people there.