Predicting quakes? Seconds may be all we have

Lessons from a deadly tsunami
Meanwhile, researchers are using information from more recent earthquakes, such as the huge temblor that caused the 2004 Indian Ocean tsunami, in an attempt to nail down longer term predictions — and, they say, are making some progress.

California Institute of Technology scientist Kerry Sieh, for instance, believes there are discernable patterns to earthquake behavior.  

Part of a team that’s been studying the 9.1-magnitude quake and tsunami centered off the Indonesian coast that killed hundreds of thousands — the 1906 quake was at least 10 times weaker — Sieh and his colleagues have been focusing on another temblor that hit the area just to the south of the original rupture, killing another 2,000 people.

Now Sieh and others believe that a third section of the same fault is on the verge of letting go. “It could devastate the coastal communities of southwestern Sumatra,” Sieh said, “It could happen tomorrow or it could happen 30 years from now, but I’d be surprised if it were delayed much beyond that.” 

According to Sieh, the behavior of the Indonesian fault shows that earthquakes are not just random events. The challenge for science is to see if those patterns can someday lead them to develop a system for earthquake predictions.

Relying on rough estimates
In the meantime, people living in earthquake zones around the world will have to live with today’s rough predictions about temblors to come. 

In the San Francisco Bay area, scientists say the odds of a major earthquake along the San Andreas or the Hayward fault lines are fairly high. “We can say that there is a 60 percent chance of an earthquake in the Bay Area in the next 30 years, Allen said, “and that allows us to build buildings that are less likely to be damaged.”

The U.S. Geological survey agrees with that prediction, putting the chances of a magnitude 6.7 or greater quake in the Bay Area at 62 percent between now and the year 2031. 

As for San Francisco itself, scientists don’t believe that pressure on the San Andreas Fault —the one that lies directly beneath the city — has built up to the point that there will be another great quake like the one in 1906 for many years, though they can’t say so with absolute certainty. 

Such is the state of the art of earthquake prediction 100 years after the “Big One.”

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