Analysis of glacial earthquakes

• Published in: Journal of Geophysical Research: Earth Surface
• Main Authors: Tsai, Victor C., Ekström, Göran
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: American Geophysical Union 2007
• Subjects: Greenland; Jensen Glacier; glacier; Jakobshavn
• Online Access: https://doi.org/10.1029/2006JF000596

In 2003, Ekström et al. reported on the detection of a new class of earthquakes that occur in glaciated regions, with the vast majority being in Greenland. The events have a characteristic radiation pattern and lack the high-frequency content typical of tectonic earthquakes. It was proposed that the events correspond to large and sudden sliding motion of glaciers. Here we present an analysis of all 184 such events detected in Greenland between 1993 and 2005. Fitting the teleseismic long-period surface waves to a landslide model of the source, we obtain improved locations, timing, force amplitudes, and force directions. After relocation, the events cluster into seven regions, all of which correspond to regions of very high ice flow and most of which are named outlet glaciers. These regions are Daugaard Jensen Glacier, Kangerdlugssuaq Glacier, Helheim Glacier, the southeast Greenland glaciers, the northwest Greenland glaciers, Rinks Isbrae, and Jakobshavn Isbrae. Event amplitudes range from 0.1 to 2.0 × 10^(14) kg m. Force directions are consistent with sliding in the direction of glacial flow over a period of about 50 s. Each region has a different temporal distribution of events. All glaciers are more productive in the summer, but have their peak activity in different months. Over the study period, Kangerdlugssuaq has had a constant number of events each year, whereas Jakobshavn had most events in 1998–1999, and the number of events in Helheim and the northwest Greenland glaciers has increased substantially between 1993 and 2005. The size distribution of events in Kangerdlugssuaq is peaked above the detection threshold, suggesting that glacial earthquakes have a characteristic size. © 2007 by the American Geophysical. Received 12 June 2006; revised 27 October 2006; accepted 22 November 2006; published 14 April 2007. We thank R. Anderson, T. Murray, S. Anandakrishnan, and an anonymous reviewer for helpful comments. This research was supported by a National Science Foundation Graduate Fellowship (VCT) and ...