Item: THE ROLE OF SLOPE ANGLE IN SKIER-TRIGGERED SLAB AVALANCHE RELEASE
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Title: THE ROLE OF SLOPE ANGLE IN SKIER-TRIGGERED SLAB AVALANCHE RELEASE
Proceedings: Proceedings, International Snow Science Workshop, Whistler, BC, Canada, 2026
Authors:
- Stephan Harvey [ WSL Institute for Snow and Avalanche Research SLF, Davos Dorf, Switzerland ]
- Alec van Herwijnen [ WSL Institute for Snow and Avalanche Research SLF, Davos Dorf, Switzerland ]
- Yannik Werner [ WSL Institute for Snow and Avalanche Research SLF, Davos Dorf, Switzerland ]
- Valentin Adam [ Technical University of Darmstadt, Institute of Structural Mechanics and Design, Darmstadt, Germany ] [ WSL Institute for Snow and Avalanche Research SLF, Davos Dorf, Switzerland ]
Date: 2026-09-28
Abstract: Slope angle is a key factor in dry-slab avalanche formation and central to avalanche education and terrain assessment. Combined with the avalanche danger rating, it is commonly used to estimate the release probability on a crux slope. Even small differences in steepness may therefore influence risk perception and decision-making. However, slope angle affects several interacting processes in slab avalanche formation, raising the question of how it influences triggering probability across the full range from flat to 45°, covering the terrain relevant for backcountry travel. This study examines the effect of slope angle on slab-avalanche formation, from failure initiation and crack propagation to slab release. We synthesise current research, apply fracture-mechanical approaches and relate slope angle to skier-induced loading and dynamics. Additionally, we analyse slope angles at release areas and trigger locations of human-triggered avalanches in Switzerland. Our findings show that slope angle has limited direct effects on failure initiation and the onset of crack propagation but influences skier loading and crack-face friction, thereby promoting dynamic crack propagation and slab release. Overall, loading type and snowpack properties often have a greater influence on release probability than small differences in slope angle. Particular caution is warranted on uniform slopes between 35° and 40°, where skier loading, crack-propagation propensity, and friction appear to combine favourably for avalanche release. Persistent weak layers have significantly lower friction angles and therefore require a more conservative approach.
Object ID: ISSW2026_FS2.4.pdf
DOI: https://doi.org/10.15788/1790098416
Language of Article: English
Presenter(s): Stephan Harvey
Keywords: slope angle, slab avalanche release, failure initiation, crack propagation, friction, skier triggering
Page Number(s): 1538 - 1545
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