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Monday, November 23, 2009

Photo: Mount St. Helens's "Drumbeat" Quakes Caused by Stuck Plug?


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A new ridge rises from the crater of Mount St. Helens on October 31, 2006. A new study says movements of the rocky "plug" capping the Washington State volcano's magma channel may be causing strange "drumbeat" earthquakes within the mountain.

Photograph by Jon Major and Dan Dzurisin, courtesy USGS