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The search for seismic signatures of movement at the glacier bed in a polythermal valley glacier

Pomeroy, Joseph; Brisbourne, Alex; Evans, Jeffrey; Graham, David. 2013 The search for seismic signatures of movement at the glacier bed in a polythermal valley glacier. Annals of Glaciology, 54 (64). 149-156. 10.3189/2013AoG64A203

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Abstract/Summary

A passive seismology experiment was conducted across the main overdeepening of Storglaciaren in the Tarfala valley, northern Sweden, to investigate the spatial and temporal distribution of basal microseismic waveforms in relation to known dynamics of this small polythermal sub-arctic glacier. The high ablation rate made it difficult to keep geophones buried and well coupled to the glacier during the experiment and reduced the number of days of good-quality data collection. The characterization of typical and atypical waveforms showed that the dominant waveforms were from near-surface events such as crevassing. Waveforms resembling basal microseismic signals were very rare, and seldom observed on more than two seismic stations simultaneously. The analysis of waveforms, amplitudes and particle motions suggested a near-field origin for most events. Even though basal sliding is known to occur in the overdeepening, no convincing examples of basal waveforms were detected, suggesting basal microseismic signals are rare or difficult to detect beneath polythermal glaciers like Storglaciaren. We discuss the reasons for failing to locate basal signals, consider the origin of common waveforms and make recommendations for setting up passive seismology experiments on glaciers with high ablation rates.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.3189/2013AoG64A203
Programmes: BAS Programmes > Polar Science for Planet Earth (2009 - ) > Ice Sheets
ISSN: 02603055
Date made live: 26 Jul 2013 12:09 +0 (UTC)
URI: http://nora.nerc.ac.uk/id/eprint/502761

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