Item: Snow stability on uniform slopes: implications for avalanche forecasting
Title: Snow stability on uniform slopes: implications for avalanche forecasting
Proceedings: 2002 International Snow Science Workshop, Penticton, British Columbia
Authors: C. Landry, K. Birkeland, K. Hansen, J. Borkowski, R. Brown, and R. Aspinall, Department of Earth Sciences, Montana State University 2U.S. Forest Service National Avalanche Center, Department of Mathematical Sciences, Montana State University
Abstract: This research investigated whether single snowpits can reliably represent snowpack stability on uniform slopes. The study utilized seven carefully selected slopes, three each in the Bridger and Madison Ranges of Southwest Montana, and one in the Columbia Mountains near Rogers Pass, British Columbia. Teams performed ten Quantified Loaded Column Tests in each of five snowpits within a 900 m2 plot at a slope, measuring shear strength in a single weak layer. Collection of slab shear stress data enabled the calculation of a strength/stress stability ratio. Altogether, eleven stability-sampling trials were performed during 2000/2001 and 2001/2002, testing several weak layer types exhibiting a wide range of strengths. Of the 54 snowpits completed, 26 pits (48%) represented plot-wide stability and 28 pits (52%) did not. One plot collapsed prior to completion of a 55th pit. Two of the eleven plots did contain full complements of five representative snowpits. The results of this study suggest the importance of improving our understanding of the processes affecting the variability of snowpack stability on any given day.
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Keywords: stability, spatial variation, avalanche forecasting
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