Glacial rumblings from Jakobshavn ice stream, Greenland

Publisher： International Glaciological Society

ISSN： 1727-5652

Source： Journal of Glaciology, Vol.55, Iss.191, 2009-06, pp. : 389-399

Disclaimer: Any content in publications that violate the sovereignty, the constitution or regulations of the PRC is not accepted or approved by CNPIEC.

Previous Menu Next

Abstract

The steep increase in Greenland's glacial earthquake activity detected by the Global Seismographic Network since the late 1990s suggests that a close inspection of these events might provide clues to the nature and origin of such seismic activity. Here we discuss the detection of large, unexpected seismic events of extraordinarily long duration (10–40 min) occurring about once every 2 days, and localized in the ice stream that feeds the Earth's fastest-moving glacier (Jakobshavn Isbræ) from the east. These 'glacial rumblings' represent an ice-mass wasting process that is greater and more frequent than glacial earthquakes have suggested. Probably triggered by calving, the rumblings are all very similar regardless of duration, and all end with a sharp, earthquake-like event in which the largest seismic amplitude is in the rumbling and that might signal the collapse of large ice masses upstream. By calculating the total amount of seismic energy released as rumblings, we estimate that the maximum seasonal amount of ice moved seismogenically down the ice stream is up to 12 km³, or ∼30% of the average annual iceberg discharge in Jakobshavn.