Abstract:
Fast-moving glaciers accommodate the majority of their motion through slip in a narrow band at the ice-bed interface, akin to slip along a tectonic fault. The processes that regulate the force balance within this narrow band, which subsequently determine glacier slip speeds, are poorly constrained. In part this is due to the relatively inaccessible nature of the glacier ice-bed interface and the inability of remote sensing techniques to shed light on the small-scale processes that regulate the system.
However, without constraining the physical processes that govern basal slip glacier flow models that attempt to predict glacier behavior will have limited utility in their predictions. To improve our understanding of glacier slip processes we employ passive seismic techniques coupled with laboratory experiments that replicate in situ conditions. Using custom designed cryogenic direct shear and ring shear laboratory devices we can constrain the basic relationships between slip velocity, effective stress, and resistive stress resulting from the physical processes of glacier slip. Then using passive seismic deployments on glaciers that allow for the detection of relatively small basal seismic events we can test the applicability of the relationships we have determined in the laboratory.
Specifically, we will use laboratory result for slip of ice over rigid glacier beds both with and without cavitation to investigate a set of glacial seismic emissions from Saskatchewan Glacier in Banff National Park, Ca, which emitted ~45,000 basal events over ~18 days.
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