Item: Dry Slab Avalanches Triggered by Skiers
Title: Dry Slab Avalanches Triggered by Skiers
Proceedings: 1990 International Snow Science Workshop, Bigfork, Montana USA, October 9-13
- Jürg Schweizer
Abstract: Most skiers buried and killed in a slab avalanche triggered "their" avalanche themselves. Avalanche forecasting should reflect this fact. In times of severe snowfall traditional avalanche forecasting is mainly based on the actual nivo-meteorological parameters. Naturally released avalanches dominate this phase, whereas slabs triggered by skiers are common in rather quiescient weather periods. At such times, forecasters follow the snow cover development closely. Analysis of snow pit data, "Rutschblock" tests and shear frame measurements represent so-called low entropy data (LaChapelle, 1980) and are most efficient for stability evaluation. Thereat it is essential to take into account the additional stress induced by the skier. Fohn (1987) explicitly introduced a stability index S' which incorporates this additional load. In the case of shallow slabs « 0.5 m) the human load is a substantial factor (Figure 1).
Language of Article: English
Keywords: stability, forecasting, rutschblock test, skiing, dry slab
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