CGRG Bibliography of Canadian Geomorphology
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Author : Clarke, G.K.C.; and Blake, E.W.
Date : 1990
Title : Temporal changes in subglacial acoustic properties
Publication : EOS
Issue : 71(43):
Page(s) : 1314-1315
Abstract
Seismic studies of west Antarctic ice stream B reveal that the S-wave velocity in underlying sediments is remarkably low. Drill holes to the base of the ice stream confirm that the subglacial material is deforming water-saturated till. This association of deformation with low S-wave velocity is expected because both are a consequence of low rigidity mu. Following this reasoning, if subglacial sediment deforms at an irregular rate then this may imply that sediment rigidity is temporally variable and that temporal variations in acoustic properties such as the P- and S-wave velocities might occur. In summer 1990 we attempted to observe temporal changes in the acoustic properties of sediment beneath Trapridge Glacier, Yukon Territory, Canada. The glacier is surge-type and is known to have spatially and temporally variable subglacial deformation rates. Our experiment involved placing a controlled seismic source near the bed of Trapridge Glacierand observing seismic arrivals using a subglacial array of five geophones. Suites of seismograms were collected at 20-minute intervals for three weeks. Subglacial water pressure and basal sliding rate near the array were continuously recorded throughout the experiment. We report the results of these seismic measurements.
Bibliography of Canadian Geomorphology