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Publication Title

Journal of Geophysical Research


American Geophysical Union

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We present the first glacier-wide detailed measurement of basal effective pressure and related observations including bed separation to elucidate the role of water in sliding. The hard bedded glacier instrumented in our study exhibited two phases of accelerated sliding motion apparently driven by separate mechanisms. The first acceleration phase (up to 5 fold increase in speed) was closely tied to an increase in bed separation. The faster second phase (up to 9 fold increase in speed) was related to an unusually high level of connectivity of subglacial waters. We infer the first mode was related to cavity opening and the second mode was related to reduced ice contact with the bed. Glacier sliding over a hard bed is typically represented by sliding laws that include the effective basal pressure, but neither sliding phase was accompanied by a simultaneous decrease in local or regional effective pressure.




An edited version of this paper was published by AGU. Copyright (2007) American Geophysical Union.


© 2007 by the American Geophysical Union

Recommended Citation

Harper, J. T., N. F. Humphrey,W. T. Pfeffer, and B. Lazar (2007), Two modes of accelerated glacier sliding related to water, Geophys. Res. Lett., 34, L12503, doi:10.1029/2007GL030233.

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