Item: Characteristics of old-deep-slab avalanches
Title: Characteristics of old-deep-slab avalanches
Proceedings: 2010 International Snow Science Workshop
Authors: David Tracz1,*, Bruce Jamieson1,2 1Dept. of Civil Engineering, University of Calgary, Alberta, Canada 2Dept. Of Geoscience, University of Calgary, Alberta, Canada
Abstract: Deep and old slab avalanches (ODS) are often hard-to-forecast. The size and destructive potential of ODS avalanches can be disturbing. As a starting point for a study of hard-toforecast avalanches we define ODS avalanches based on a large dataset spanning the three main mountain ranges of western Canada: Coast, Columbia and Rocky Mountains. The definition is based on extreme slab depth and extreme age of the snowpack weakness that failed. Our data did not reveal a difference in slope angle or aspect between the ODS and “Other” avalanches. However, compared to Other avalanches, ODS avalanches were typically of greater size, involved less human triggering, released more often on crusts and weak layers of facets and tended to occur more often in early winter.
Keywords: avalanches, slab depth, age