SEISMOLOGISTS studying how small earthquakes can trigger much bigger ones have detailed the exact sequence of events that could unleash a major quake near Los Angeles, home to 13 million people. The study will help seismologists worldwide make more accurate predictions of regional risks.
Greg Anderson and two colleagues at the US Geological Survey in Pasadena, California, were worried that the Los Angeles basin might be prone to the same kind of cascade effect that unleashed a massive quake at Denali in southern Alaska last year. There, a small earthquake on 3 November created stresses that led to a magnitude-8 monster 11 days later. "It got people thinking it could take place in southern California," says Anderson.
His team attacked the problem by creating three-dimensional computer models of the Los Angeles region, which is criss-crossed by a web of vertical strike-slip faults and sloping thrust faults. The models included the ...
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