Item: A Mechanism for Cooling-Related Slab Avalanche Release
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Title: A Mechanism for Cooling-Related Slab Avalanche Release
Proceedings: Proceedings, 2012 International Snow Science Workshop, Anchorage, Alaska
Authors:
- James A. Floye [ Canadian Avalanche Centre, Revelstoke BC Canada ]
Date: 2012
Abstract: Strong anecdotal evidence exists suggesting cooling is an important factor for slab avalanche release. Despite this, a viable mechanism for it has not yet been formally proposed. This paper describes a mechanism combining enhanced cohesion of the upper slab (caused by a cooling-driven reduction in viscosity) with lateral variations in the weak layer depth. A critical component of the model is that sufficient creep is retained in the mid portion of the slab. This enables higher strain rates to be transmitted to a part of the slope where the weak layer is buried at a shallower depth. As a result of the model constraints, it is likely the physical state of the snowpack corresponding to that described in the model occurs under very specific conditions. This is consistent with observations of the phenomenon, which indicate cooling-driven slab avalanches are relatively uncommon, but when they do occur, often happen within a specific window a short time after the onset of cooling. Other potential mechanisms are also examined. These are: thermal expansion or contraction of the slab; increased brittleness of the slab; and changes to weak layer properties.
Object ID: issw-2012-252-255.pdf
Language of Article: English
Presenter(s): Unknown
Keywords: slab release, strain rate, weak layer, near-surface temperature change
Page Number(s): 252-255
Subjects: slab avalanches weak layers
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