Diurnal variations in vertical strain observed in a temperate valley glacier

Sugiyama, Shin and Gudmundsson, Hilmar (2003) Diurnal variations in vertical strain observed in a temperate valley glacier. Geophysical Research Letters, 30 (2). 62-1-62-4. ISSN 0094-8276

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Abstract

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
Subjects:	F800 Physical and Terrestrial Geographical and Environmental Sciences
Department:	Faculties > Engineering and Environment > Geography and Environmental Sciences
Depositing User:	Becky Skoyles
Date Deposited:	14 Feb 2019 11:59
Last Modified:	10 Oct 2019 23:46
URI:	http://nrl.northumbria.ac.uk/id/eprint/38002

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