Journal cover Journal topic
The Cryosphere An interactive open-access journal of the European Geosciences Union
The Cryosphere, 9, 795-804, 2015
https://doi.org/10.5194/tc-9-795-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
27 Apr 2015
Influence of weak layer heterogeneity and slab properties on slab tensile failure propensity and avalanche release area
J. Gaume1, G. Chambon2,3, N. Eckert2,3, M. Naaim2,3, and J. Schweizer1 1WSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland
2Irstea, UR ETGR, Grenoble, France
3Université Grenoble Alpes, Grenoble, France
Abstract. Dry-snow slab avalanches are generally caused by a sequence of fracture processes, including failure initiation in a weak snow layer underlying a cohesive slab followed by crack propagation within the weak layer (WL) and tensile fracture through the slab. During past decades, theoretical and experimental work has gradually increased our knowledge of the fracture process in snow. However, our limited understanding of crack propagation and fracture arrest propensity prevents the evaluation of avalanche release sizes and thus impedes hazard assessment. To address this issue, slab tensile failure propensity is examined using a mechanically based statistical model of the slab–WL system based on the finite element method. This model accounts for WL heterogeneity, stress redistribution by slab elasticity and possible tensile failure of the slab. Two types of avalanche release are distinguished in the simulations: (1) full-slope release if the heterogeneity is not sufficient to stop crack propagation and trigger a tensile failure within the slab; (2) partial-slope release if fracture arrest and slab tensile failure occur due to the WL heterogeneity. The probability of these two release types is presented as a function of the characteristics of WL heterogeneity and the slab. One of the main outcomes is that, for realistic values of the parameters, the tensile failure propensity is mainly influenced by slab properties. Hard and thick snow slabs are more prone to wide-scale crack propagation and thus lead to larger avalanches (full-slope release). In this case, the avalanche size is mainly influenced by topographical and morphological features such as rocks, trees, slope curvature and the spatial variability of the snow depth as often claimed in the literature.

Citation: Gaume, J., Chambon, G., Eckert, N., Naaim, M., and Schweizer, J.: Influence of weak layer heterogeneity and slab properties on slab tensile failure propensity and avalanche release area, The Cryosphere, 9, 795-804, https://doi.org/10.5194/tc-9-795-2015, 2015.
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Short summary
Slab tensile failure propensity is examined using a mechanical--statistical model of the slab–-weak layer (WL) system based on the finite element method. This model accounts for WL heterogeneity, stress redistribution by elasticity of the slab and the slab possible tensile failure. For realistic values of the parameters, the tensile failure propensity is mainly driven by slab properties. Hard and thick snow slabs are more prone to wide–scale crack propagation and thus lead to larger avalanches.
Slab tensile failure propensity is examined using a mechanical--statistical model of the...
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