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The dynamic response of Kennicott Glacier, Alaska, USA, to the Hidden Creek Lake outburst flood

January 1, 2005

Glacier sliding is commonly linked with elevated water pressure at the glacier bed. Ice surface motion during a 3 week period encompassing an outburst of ice-dammed Hidden Creek Lake (HCL) at Kennicott Glacier, Alaska, USA, showed enhanced sliding during the flood. Two stakes, 1.2 km from HCL, revealed increased speed in two episodes, both associated with uplift of the ice surface relative to the trajectory of bed-parallel motion. Uplift of the surface began 12 days before the flood, initially stabilizing at a value of 0.25 m. Two days after lake drainage began, further uplift (reaching 0.4 m) occurred while surface speed peaked at 1.2 m d-1. Maximum surface uplift coincided with peak discharge from HCL, high water level in a down-glacier ice-marginal basin, and low solute concentrations in the Kennicott River. Each of these records is consistent with high subglacial water pressure. We interpret the ice surface motion as arising from sliding up backs of bumps on the bed, which enlarges cavities and produces bed separation. The outburst increased water pressure over a broad region, promoting sliding, inhibiting cavity closure, and blocking drainage of solute-rich water from the distributed system. Pressure drop upon termination of the outburst drained water from and depressurized the distributed system, reducing sliding speeds. Expanded cavities then collapsed with a 1 day time-scale set by the local ice thickness.

Publication Year 2005
Title The dynamic response of Kennicott Glacier, Alaska, USA, to the Hidden Creek Lake outburst flood
DOI 10.3189/172756405781813438
Authors R. Scott Anderson, J. S. Walder, S.P. Anderson, D.C. Trabant, A. G. Fountain
Publication Type Article
Publication Subtype Journal Article
Series Title Annals of Glaciology
Index ID 70027341
Record Source USGS Publications Warehouse