Fracture character in compression tests

Stability tests are widely used to identify and qualify potential failure layers for slab avalanches. As an addition to stability test scores, researchers at the University of Calgary have been systematically classifying fractures in compression and rutschblock tests since the winter of 1996–1997. The classification system comprises five categories: Progressive Compression (PC), Resistant Planar (RP), Sudden Planar (SP), Sudden Collapse (SC) and non-planar Break (B). Some 2654 fractures were classified in compression tests performed at study slopes in the Columbia Mountains of British Columbia, Canada. Specific snowpack characteristics, including hardness difference and difference in crystal size across the failure layer, associated with the different fracture characters were identified. Data from skier-tested slopes show that fracture characterization can improve the interpretation of compression test results. Sudden fractures (Sudden Collapse and Sudden Planar) are more often the failure layer of slab avalanches than other fractures.