Item: The PST with a Twist: Comparing the Standard PST to the Cross Slope PST
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Title: The PST with a Twist: Comparing the Standard PST to the Cross Slope PST
Proceedings: International Snow Science Workshop 2014 Proceedings, Banff, Canada
Authors:
- Eric Knoff [ Gallatin National Forest Avalanche Center, Bozeman, MT, USA ]
Date: 2014-09-29
Abstract: In recent years, the propagation saw test (PST) gained popularity for both avalanche professionals and backcountry recreationalists. A limiting factor of the PST is the additional time required to isolate a column on the sidewall of the snowpit. Since I often have limited time to dig multiple pits during a work day, this past season I examined the effectiveness of conducting cross-slope PSTs (CPST). The CPST is simply a PST done across, rather than up, the slope. It is more efficient than the PST, particularly after conducting an extended column test (ECT). I collected a total of 28 data sets, including standard PSTs, CPSTs and ECTs during the 2013/14 winter season. My data indicate that CPSTs share similar critical cut lengths as standard PSTs, with 75% of critical cut lengths falling within 10 cm of each other. Though it is necessary to collect more data to make solid conclusions, there may be a slope angle effect where CPSTs begin to have shorter cut lengths than standard PSTs as slope angles increase above 28 or 30 degrees. A drawback of the CPST is that some weak layers may be more difficult to follow than in a standard PST. Currently, the CPST cannot be qualified as a standardized stability test, but I hope to continue to collect additional data to better understand how CPSTs are related to PSTs and snowpack stability.
Object ID: ISSW14_paper_P2.30.pdf
Language of Article: English
Presenter(s):
Keywords: propagation saw test (PST), cross-slope propagation saw test (CPST), extended columntest (ECT), critical cut length, slope-angle, fracture propagation
Page Number(s): 810-814
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