International Snow Science Workshop Proceedings - Montana State University Library

Item: Comparison of Structural Instability Indices (Lemons), ECT and RB Results

• • Title: Comparison of Structural Instability Indices (Lemons), ECT and RB Results

    Proceedings: International Snow Science Workshop Grenoble – Chamonix Mont-Blanc - October 07-11, 2013

    Authors:

    • Chiambretti Igor  [ AINEVA, Trento (TN), Italy ]
    • Fabiano Monti  [ SLF, Davos, Switzerland ]
    • Mauro Valt  [ ARPA Veneto - Centro Valanghe di Arabba, Arabba (BL), Italy ]

    Date: 2013-10-07

    Abstract: Almost all avalanche forecasting services have a network of traditional stations where an array of daily or weekly snowpack measurement or observations are made (ram penetrometer, snow profile, stability tests). Ram penetrometer and snow profile data are classified as medium entropy type while stability test are a low entropy ones and they requires an interpretation by the avalanche forecaster. In recent years, several methods have been developed to analyze the profiles and to evaluate, more objectively, snowpack stability identifying the weak layers and their characteristics and properties. During the period 2010-2013 several AINEVA’s regional offices have collected a dataset consisting of hundreds of snow profile each accompanied by side-by-side stability tests (ECT and/or RB). A sample of this data set was analyzed following the critical variables method and finding interesting relations between weak layer characteristics (structural instability indices or “lemons”, grain type, layer thickness, weak layer properties) and stability test results. The preliminary data of this research project are here discussed and shows that the best correlation between the highest values of the structural instability indices and stability test results are detectable for weak layers developed due to medium to high temperature gradient metamorphism. Less good correlation have been detected for weak layers composed by new snow (PP and DF) or by various type of crust or smooth interface between layers. The complete data set has been, finally, analyzed to compare ECT versus RB effectiveness in discriminating the main weak layer and finding relations between load steps, fracture character and depth, quality shear and weak layer characteristics.

    Object ID: ISSW13_paper_O5-03.pdf

    Language of Article: English

    Presenter(s): Unknown

    Keywords: rb, ect, structural instability indices

    Page Number(s): 357-362

    Subjects: snow instability avalanche forecasting weak layers

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