Cause of glacial earthquakes in Greenland attributed to major ice calving events

January 4th, 2009 - 2:15 pm ICT by ANI  

Washington, Jan 4 (ANI): Scientists have clarified that glacial earthquakes in Greenland are caused by major ice calving events, not glacier lurching.

Satellite observations during the past decade have shown dramatic changes in flow speed on year-to-year timescales at Greenland’’s outlet glaciers.

Seismic events traced back to glaciers during the same time period have been interpreted to have resulted from calving events at the glacier terminus or surging events lubricated by subglacial meltwater.

To learn more, M. Nettles and G. Ekstrom from Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York, US, conducted geodetic studies at Helheim Glacier, one of Greenland’’s largest outlet glaciers, during summer 2007.

They observed several large and sudden increases in flow speed along the length of the glacier. These accelerations coincided with glacial earthquakes and major iceberg calving events.

No offset in the position of the glacier surface was observed during these events.

Instead, modest tsunamis associated with the glacial earthquakes implicate glacier calving as the generator of seismic events, putting to rest the idea that lurching glaciers are responsible for glacial earthquakes at outlet glaciers like Helheim, and demonstrating a link between ice loss and glacier acceleration. (ANI)

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