Item: Shear strength and snowpack stability trends in non-persistant weak layers
Title: Shear strength and snowpack stability trends in non-persistant weak layers
Proceedings: Proceedings Whistler 2008 International Snow Science Workshop September 21-27, 2008
Authors: Ms. Catherine Brown, Dr. Bruce Jamieson.
Abstract: Non-persistent weak layers in storm snow exhibit rapidly changing physical and mechanical properties. The shear strength and its rate of change, relevant to storm snow slab avalanches and rarely measured. To measure the shear strength we performed up to 10 sets of 12 shear frame tests for 16 separate storm snow weak layers. Layers were sampled once or twice a day resulting in over 1100 shear frame tests at the Mt. Fidelity, Rogers Pass and Blue River study plots during the winters of 2006 and 2007 in the Columbia Mountains of British Columbia, Canada. Snowpack properties, including overlying load, densities, temperature gradient and crystal types, of the weak layer and adjacent layers were measured, along with atmospheric conditions. We present an empirical strength change model, based on the properties with the greatest influence on strength changes in the weak layers. The model predicts shear strength on a given day, based on standard field measurements, and forecasts the strength of the layer. We compare our measured and modeled strength with output from SNOSS.
Presenters: Ms. Catherine Brown.
Keywords: shear strength, snow stability, avalanche forecasting, non-persistent weak layers