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Greenland glacial quakes becoming more common

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1:26pm, April 25, 2006

The number of earthquakes that occur beneath surging glaciers in Greenland has doubled in the past 4 years, another possible effect of the melting ice sheet there.

Just 2 years ago, scientists reported a newly recognized phenomenon: earthquakes occurring beneath glaciers, probably from sudden slips of those ice masses (SN: 1/3/04, p. 14: Available to subscribers at Earth sometimes shivers beneath thick blankets of ice). The magnitudes of those quakes, which aren't associated with known faults, measure between 4.6 and 5.1, says Göran Ekström, a geophysicist at Harvard University.

Seismic data gathered from 1993 to late 2005 identify 136 quakes along the southeastern and southwestern coasts of Greenland, all of them originating beneath glaciers that flow at the fast pace of at least 2 kilometers each year, says Ian Joughin, a glaciologist at the University of Washington in Seattle.

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