open access

https://hdl.handle.net/2115/4854

Diurnal variations in vertical strain observed in a temperate valley glacier

英語

2003-01-30

American Geophysical Union

Geophysical Research Letters

30(2)

An edited version of this paper was published by AGU. Copyright 2003, American Geophysical Union, Geophysical Research Letters, 30-2

During a period of diurnal fluctuations in glacial flows speed, vertical strain was measured with sub-daily temporal resolution on Unteraargletscher, Switzerland. Mean vertical strain in boreholes up to 300-m deep out of 400-m-thick ice was found to fluctuate diurnally. Vertical strain rates were extensile 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 pressures suggesting a basal control on temporal flow variations. Nevertheless, the strain rate measurements indicated that changes in surface flow speed is 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 important role in short-term glacial flow fluctuations.

学術雑誌論文

Accepted Manuscript

0094-8276