Dry snow slab shear fracture speeds

Abstract

Dry snow slab avalanches release by propagating shear fractures within thin weak layers underneath thicker, stronger planar slabs. In this paper, measured shear fracture speeds from small scale snow slabs are compared with theoretical estimates compatible with dynamic fracture mechanics. Given the important physical quantities including density and elastic shear modulus, it is concluded that estimated snow slab shear fracture speeds scale with the shear wave speed similar to estimates in other geophysical applications including shear fractures from earthquakes and in engineering materials. However, the constant of proportionality is much lower than for alpine snow than for earthquakes and engineering materials. The lower constant of proportionality may indicate the possibility of important energy dissipation mechanisms in snow avalanche fracture propagation. Copyright 2007 by the American Geophysical Union.