Major earthquakes occurring along the Cascadia subduction zone off the coast of Washington state could strike closer to the state’s urban areas than some models have suggested, a new study notes.
GPS data gathered at dozens of sites throughout western Washington hint that slippage along the interface between the North American and Juan de Fuca tectonic plates could occur as deep as 25 kilometers below the Earth’s surface, says Timothy I. Melbourne, a geodesist at Central Washington University in Ellensburg. That depth, in turn, would place the epicenters of quakes triggered along that portion of the subduction zone — some of which could exceed magnitude 9 —more than 60 kilometers inland, he and CWU colleague James Chapman report online and in the November 28 Geophysical Research Letters.
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