Modeling Crack Arrest in Snow Slab Avalanches—Toward Estimating Avalanche Release Sizes

Abstract Dry‐snow slab avalanches are the most fatal type of avalanches, beginning with the failure of a weak snow layer below cohesive slabs. This failure can propagate within the weak layer, causing the overlying slab to fracture and slide. Avalanche forecasters are interested in evaluating crack propagation propensity and potential avalanche sizes. This study tests the hypothesis that two factors may stop dynamic crack propagation: snowpack heterogeneity and terrain variations. We develop a depth‐averaged Material Point Method, which combines MPM with shallow water assumptions for efficient elastic‐brittle modeling of avalanche release. We analyze two scenarios: pure‐elastic and brittle slabs. In the pure‐elastic case, we observe a significant decrease in slab tensile stress with increasing crack speed and provide an analytical formulation for this phenomenon. We evaluate the impacts of weak layer heterogeneity and fracture energy on crack stopping. In the brittle scenario, we explore the interaction between weak layer heterogeneity and slab fracture, quantifying their combined effects on crack arrest. Our results reveal a scaling law that relates crack arrest distance to dimensionless numbers indicative of weak layer and slab strength. The model is applied in case studies to predict release sizes based on field data, and also on synthetic 3D topographies, enhancing the understanding of factors influencing avalanche size and aiding future mitigation strategies.