A scale-invariant model for snow slab avalanches

On the basis of the evidence of fractality reported in the literature as regards snow material and snow avalanches, the paper introduces a statistical model for the natural release of slab avalanches characterized by the differing cohesion of the snow cover at different scales. Under the hypothesis of scale invariance of shear strength, this model can be used to estimate the stability of snow slopes of different types, and to examine whether defects can propagate from the microscale (cohesion and friction) to the macroscale of the weak plane (big avalanche) or whether they eventually stop at a certain scale (small event). This may shed light on the apparently inexplicable differences in behaviour of snow covers which look macroscopically similar, under the same mechanical loads, and which may eventually trigger an avalanche or not.