Item: GRAUPEL, CRUSTS, PERSISTENT INSTABILITY, AND UNUSUAL SLAB BEHAVIOR: TWO CASE STUDIES FROM MOUNT SHASTA, CALIFORNIA, USA
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Title: GRAUPEL, CRUSTS, PERSISTENT INSTABILITY, AND UNUSUAL SLAB BEHAVIOR: TWO CASE STUDIES FROM MOUNT SHASTA, CALIFORNIA, USA
Proceedings: Proceedings, International Snow Science Workshop, Whistler, BC, Canada, 2026
Authors:
- Christian Jordan [ USDA Forest Service Mount Shasta Avalanche Center, Mount Shasta, California, USA ]
- Eric Falconer [ USDA Forest Service Mount Shasta Avalanche Center, Mount Shasta, California, USA ]
- Hayden MacArthur [ USDA Forest Service Mount Shasta Avalanche Center, Mount Shasta, California, USA ]
- Jeremy J. Axelrod [ Stanford University, California, USA ]
- Zach Guy [ Crested Butte Avalanche Center, Crested Butte, Colorado, USA ]
- Nick Meyers [ USDA Forest Service Mount Shasta Avalanche Center, Mount Shasta, California, USA ]
Date: 2026-09-28
Abstract: These case studies examine two large natural avalanches attributed to graupel/crust combinations on Mount Shasta, California. The first case study details an avalanche in February 2026 which released on a layer of buried graupel above a melt-freeze crust after a major loading event. The graupel layer provided limited feedback before failing ten days after burial – one of the longest documented cases of persistent instability associated with this grain type. A second notable avalanche in April 2026 highlights a graupel/crust combination as a problematic weak layer with wide-propagation potential. These case studies provide further evidence that graupel can act as a persistent weak layer, result in widely-propagating avalanches, and challenge forecasting operations.
Object ID: ISSW2026_P4.13.pdf
DOI: https://doi.org/10.15788/1790099268
Language of Article: English
Presenter(s): Christian Jordan
Keywords: Graupel; Persistent Weak Layer; Persistent Slab; Melt-Freeze Crust
Page Number(s): 608 - 614
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