Quake Project Aimed to ID Future Hotspots

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Scientists have embarked on an ambitious experiment to better anticipate earthquakes by identifying the likeliest places where magnitude-4.9 quakes or stronger will occur in seismically active California over a five-year period.

Half a dozen teams have developed sophisticated computer models, and submitted their best guesses. As part of the ground rules, they could not change their forecasts, which were checked against actual quakes that hit during the study period. The goal was to see whether there was a reliable way to flag a seismic hotspot before the ground shakes.

The exercise began in 2006 and wrapped up last December. Researchers were asked to pinpoint regions where quakes were more likely to occur based on past seismic history, activity on fault lines or other factors.

During the test period, 31 quakes larger than magnitude-4.9 rattled the state, including the greater Los Angeles region, San Francisco Bay area and off the Northern California coast. The largest was the 2010 Easter earthquake centered in Baja California.

So how did scientists do?

“No single model takes home all the gold,” said seismologist John Vidale of the University of Washington who was not part of any team. But three groups that took into account all past quakes regardless if they were big or small fared better than the rest.

Seismologist David Jackson of the University of California, Los Angeles, likened the experiment to small children playing football. There are “no official winners or losers, but plenty of scorekeeping from the sidelines” to learn the strengths and weaknesses of various quake theories, Jackson said.

While scientists cannot say with certainty exactly when and where the next quake will strike, they have an idea of how quakes behave. For example, a big quake will produce smaller aftershocks in the same area. There’s still a lot that’s unknown such as whether quakes too small to be felt play a role in increasing the chances of a bigger quake.