parameterized the model and wrote the manuscript. Supplementary information is available in the online version of the paper. Additional information References [1] Wu, Q., Andreopoulos, Y., Xanthos, S., and S. Weinbaum (2005), Dynamic compression of highly compressible porous media with application to snow compaction, J. Fluid Mech., 542 , 281–304. [2] Schweizer, J. (1999), Review of dry snow slab avalanche release Cold Regicons Sci. Technol., 30 , 43-57. [4] De Montmollin, V. (1982), Shear tests on snow explained by fast metamorphism. J. Glaciology, 28 187-198. [3] Blackford, J.R. (2007) Sintering and microstructure of ice: a review. J. Phys. D: Applied Physics. 40 , R355-R385. [5] Kinosita, S. (1967), Compression of snow at constant speed. Phys. Snow Ice: proceedings, 2 911-927. [6] Zaiser, M., and P. Hähner (1997), A unified description of strain-rate softening instabilities, Mater. Sci. Engng A , 238 , 399-406. [7] Zaiser, M., and P. Hähner (1997), Oscillatory modes of plastic deformation - theoretical concepts, phys. stat. sol. (b) , 99 , 267-330. [8] Zaiser, M., M. Glazov, L. A. Lalli and O. Richmond (1999), On the Relations Between Strain and Strain Rate Softening Phenomena in Some Metallic Materials, Comp. Mater. Sci. , 15 , 35-49. [9] Zaiser, M., Mill, F., Konstantinidis, A., Aifantis, K.E. (2013), Strain Localization and Strain Propagation in Collapsible Solid Foams, Mater. Sci. Engng. , A 567 , 38-45. [10] Deshpande, V.S. and Fleck, N.A. (2001), Multi-axial yield behaviour of polymer foams, Acta Mater. , 49 , 1859–1866. [11] McClung, D.M. (1979), Shear fracture precipitated by strain softening as a mechaisms for dry slab avalanche release, J. Geophys. Res. , 84 , 3519-3526. [12] Gibson, L.J. and M.F. Ashby (1988), Cellular Solids: Structure and Properties , Pergamon, Oxford. 11