HR: 14:10h
AN: C22A-03    [PDF]
TI: Load Sensitivity of a Surge-Type Glacier
AU: * Clarke, G K
EM: clarke@eos.ubc.ca
AF: University of British Columbia, Earth and Ocean Sciences 6339 Stores Road, Vancouver, BC V6T 1Z4 Canada
AB: During the winter season Trapridge Glacier, Yukon, Canada, is subject to puzzling short-lived mechanical events. Such events are characterized by a pronounced increase in icequake activity, abrupt changes in the internal ice strain, and rapid local adjustments of the mechanical interaction between the glacier and its bed. Although the events are closely monitored by a network of englacial and subglacial instruments (including geophones and sensors to measure vertical strain, subglacial water pressure, basal sliding, and sediment strength) it has been unclear, until recently, whether the events are internally or externally triggered. Observations during the winters of 1999--2000 and 2002--2003 indicate that the events are externally triggered and that the forcing mechanism is rapid barometric and/or precipitation loading of the glacier surface. Such sensitivity to small changes in loading is unexpected and suggests that some fraction of the sediment substrate of Trapridge Glacier is near the threshold for mechanical failure. Winter triggering of glacier surges might be explained by fast surface loading.
DE: 1827 Glaciology (1863)
DE: 1863 Snow and ice (1827)
SC: Cryosphere [C]
MN: 2003 Fall Meeting