Item: On Snow Avalanche Flow Regimes: Inferences from Observations and Measurements
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Title: On Snow Avalanche Flow Regimes: Inferences from Observations and Measurements
Proceedings: Proceedings Whistler 2008 International Snow Science Workshop September 21-27, 2008
Authors:
- Peter Gauer [ Norwegian Geotechnical Institute, Postboks 3930 Ullev ÌŠ al Stadion, 0806 Oslo, Norway ] [ International Centre for Geohazards, c/o Norwegian Geotechnical Institute, Oslo, Norway ]
- Dieter Issler [ Norwegian Geotechnical Institute, Postboks 3930 Ullev ÌŠ al Stadion, 0806 Oslo, Norway ] [ International Centre for Geohazards, c/o Norwegian Geotechnical Institute, Oslo, Norway ]
- Karstein Lied [ Norwegian Geotechnical Institute, Postboks 3930 Ullev ÌŠ al Stadion, 0806 Oslo, Norway ]
- Krister Kristensen [ Norwegian Geotechnical Institute, Postboks 3930 Ullev ÌŠ al Stadion, 0806 Oslo, Norway ]
- Frode Sandersen [ Norwegian Geotechnical Institute, Postboks 3930 Ullev ÌŠ al Stadion, 0806 Oslo, Norway ]
Date: 2008-09-22
Abstract: Mixed dry-snow avalanches are commonly thought to consist of a dense core and a dilute suspension layer, even though observations and measurements from Canada and Russia have long indicated the presence of an intermediate-density layer ("light flow" or "saltation layer"). We summarize field observations and measurements from Norway and Switzerland, both from spontaneous events and from avalanches released at the test sites Ryggfonn and Vall 'ee de la Sionne. Deposition patterns, highfrequency impact pressure records and radar measurements show that a substantial mass fraction of mixed dry-snow avalanches is flowing in this "fluidized" regime, particularly the head. Based on mechanical considerations, we suggest close correspondence with the grain-inertia regime observed in granular flows; however, the role that the interstitial air plays in avalanches is not clarified at present. Distinguishing between three avalanche flow regimes instead of only two may have important consequences in hazard mapping and the design of protection measures.
Object ID: P__8041.pdf
Language of Article: English
Presenter(s): Peter Gauer
Keywords: avalanche dynamics, flow regimes, observations, measurements
Page Number(s): 717
Subjects: fracture mechanics avalanche dynamics
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