Diurnal variations in vertical strain observed in a temperature valley glacier

Shin Sugiyama*, G. Hilmar Gudmundsson

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

20 Citations (Scopus)


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.

Original languageEnglish
Pages (from-to)62-1 - 62-4
Number of pages2
JournalGeophysical Research Letters
Issue number2
Early online date30 Jan 2003
Publication statusPublished - Jan 2003
Externally publishedYes


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