Diurnal variations in vertical strain observed in a temperate valley glacier

Sugiyama, Shin; Gudmundsson, G. Hilmar. 2003 Diurnal variations in vertical strain observed in a temperate valley glacier. Geophysical Research Letters, 30 (2), 1090. 4, pp. 10.1029/2002GL016160

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Abstract/Summary

During a period of diurnal fluctuations in glacial flow speed, vertical strain was measured with sub-daily temporal resolution on Unteraargletscher, Switzerland. Mean vertical strain in boreholes up to 300-m deep in 400-m-thick ice was found to fluctuate diurnally. Vertical strain rates were tensile in the daytime and compressive at night, with a magnitude of up to 10(-3) day(-1). Horizontal surface strain was observed to fluctuate in a manner consistent with the vertical deformation. Diurnal surface flow speed variations correlated well with basal water pressure suggesting a basal control on temporal flow variations. Nevertheless, the strain rate measurements indicated that changes in surface flow speed are affected by internal ice deformation and not a direct measure of local basal motion. Basal conditions in the surrounding neighborhood and their temporal variations take an important role in short-term glacial flow fluctuations.

Item Type:	Article
Identification Number/DOI:	10.1029/2002GL016160
Programmes:	BAS Programmes > Antarctic Science in the Global Context (2000-2005) > Global Interactions of the Antarctic Ice Sheet
ISSN:	0094-8276
NORA Subject Terms:	Glaciology
Date made live:	13 Feb 2012 14:50
URI:	http://nora.nerc.ac.uk/id/eprint/12983

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