Item: The stuffblock: a simple and effective snowpack stability test
Title: The stuffblock: a simple and effective snowpack stability test
Proceedings: Proceedings of the 1994 International Snow Science Workshop, Snowbird, Utah, USA
Authors: Ron Johnson and Karl Birkeland
Abstract: The stuftblock is a new snow stability test developed and used operationally by the Gallatin National Forest Avalanche Center during the 1993-94 winter. Shortcomings of other stability tests, including the inability to effectively communicate results, the complexity of the test, and the time necessary to collect a measurement make the development of a new test desirable. The stuffblock is performed on an isolated column of snow about 0.30 m (l ft) square which is cut out of the wall of a snow pit. A nylon sack (stuff sack) is filled with 4.5 kg (10 lbs) of snow, which is measured with a lightweight scale. An avalanche shovel blade is placed on top of the isolated column and the stuff sack is first placed, then dropped onto the shovel from increasing heights. The drop height is increased in increments of 0.10 m. When shear failure occurs, the drop height is noted. Initial results from the 1993-94 field season indicate that, for snowpack conditions found in southwest Montana, a positive relationship exists between stuffblock drop heights and rutschblock numbers. While the stuffblock is not perfect, it is inexpensive, quick, easy, and provides numbers that can be readily compared between observers. This latter attribute is especially useful for regional avalanche forecasters who must often compare the results of several different observers with differing avalanche skills. For the individual avalanche worker, the stuffblock provides one more useful tool for snowpack stability evaluation.
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Keywords: stuffblock, stability tests, forecasting
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