RESIDENTS OF AREAS prone to earthquakes would give a lot to know when and where the next one will hit. Scientists haven't had much luck predicting when quakes will strike, but a study published in the journal Science suggests that the likely locations of future quakes can be figured out by studying the epicenters of earlier ones.
Using a wealth of data gleaned from measurements made by lasers and satellite tracking systems, geophysicists from the University of California at Los Angeles have found that regions of highest stress were not on the major faults in California, as expected, but in the regions surrounding previous earthquakes. After a quake, says Li-yu Sung, an assistant researcher at UCLA and co-author of the report, the Earth's crust continues to deform as the energy trapped in the rocks is pushed deeper into the ground. "People don't observe these post-seismic effects," says Sung, "because there are no surface ruptures."
While the notion that past earthquakes disturb a larger area is not new, the researchers say they were "stunned" by the dominance of these post-seismic strains. By examining these areas more closely, the researchers say they could better understand the potential for a quake in a given area.