Diurnal variations in vertical strain observed in a temperate valley glacier
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説明
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.
収録刊行物
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- Geophysical Research Letters
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Geophysical Research Letters 30 (2), 2003-01-30
American Geophysical Union