News & AnalysisSeismology

A Tantalizing View of What Set Off Japan's Killer Quake

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Science  20 Jan 2012:
Vol. 335, Issue 6066, pp. 272
DOI: 10.1126/science.335.6066.272

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Summary

Japanese scientists combing through the vast jumble of seismic signals recorded in the days before the great magnitude-9.0 Tohoku earthquake that ravaged their homeland have just sorted out more than 1000 newly recognized earthquakes. The find reveals how the lethal offshore fault slipped slowly just before it ripped loose. That slow slip now appears to have loaded the fault to the breaking point, triggering the devastating quake last March. The work—the fruit of decades of intensive monitoring around Japan—gives seismologists a much-anticipated peek into a fundamental mystery: "How does a big earthquake happen?"