International Snow Science Workshop Proceedings - Montana State University Library

Item: Estimated evolution of the speed of powder, wet and transitional avalanches between two widely spaced locations at the VDSL experimental site extracted from the analysis of seismic signals

• • Title: Estimated evolution of the speed of powder, wet and transitional avalanches between two widely spaced locations at the VDSL experimental site extracted from the analysis of seismic signals

    Proceedings: International Snow Science Workshop Proceedings 2018, Innsbruck, Austria

    Authors:

    • E. Suriñach  [ RISKNAT Avalanches Research Group - Institut Geomodels, Universitat de Barcelona (UB), Barcelona 08028, Spain ]  [ Laboratori d'Estudis Geofísics Eduard Fontserè (LEGEF-IEC), Barcelona 08001, Spain ]
    • Elsa Leticia Flores-Márquez  [ Instituto de Geofisica, UNAM, Circuito Instituto S/N, Coyoacán, 04510 CDMX, México ]
    • C. Pérez-Guillén  [ RISKNAT Avalanches Research Group - Institut Geomodels, Universitat de Barcelona (UB), Barcelona 08028, Spain ]  [ Graduate School of Environmental Studies, Nagoya University, Nagoya, Japan ]
    • P. Roig-Lafon  [ RISKNAT Avalanches Research Group - Institut Geomodels, Universitat de Barcelona (UB), Barcelona 08028, Spain ]
    • M. Tapia  [ Laboratori d'Estudis Geofísics Eduard Fontserè (LEGEF-IEC), Barcelona 08001, Spain ]
    • G. Furdada  [ RISKNAT Avalanches Research Group - Institut Geomodels, Universitat de Barcelona (UB), Barcelona 08028, Spain ]

    Date: 2018-10-07

    Abstract: The evolution of a snow avalanche descending along a path is reflected in the evolution of the frequency content of the generated seismic signals (spectrograms) recorded by seismic sensors located along the avalanche path. The wave transmission characteristics in the ground account for this. The analysis of spectrograms of seismic signals generated by snow avalanches of different size and type that descend along the same path at the Vallée de la Sion (VdLS, Valais, Switzerland) experimental site (SFL, Davos) allows us to estimate features related to the evolution of avalanche flow behavior. Given that the frequency content in the spectrograms increases in time as the avalanche approaches the sensor owing to the attenuation of seismic waves, the evolution of an avalanche can be estimated from the exponential function of time in the form F (t) = К’ e t fitted in the spectrograms. The avalanche speed is involved in . The values of the coefficients of the fits obtained for the three different types of avalanches are included in three ranges. We treat the spectrograms as an image to apply the Hough Transform (HT) to obtain the parameters of its shape. For the highest location, in the avalanche track-zone, the curves collapse (are grouped) reflecting different tendencies according to the type of avalanche. The curves at the lowest location are gentler and show a more homogeneous behavior regardless of the type of avalanche. Nevertheless, the peculiarities of each type persist, although the fitted curves for the powder avalanches and transitional avalanches are more prone to collapse than those of wet avalanches. Our results show the feasibility of classifying the type of avalanche using the characteristics of the frequency-in-time evolution of avalanche seismic signals. Estimates of the mean speeds of the approaching avalanches were calculated at the recording sites.

    Object ID: ISSW2018_O07.5.pdf

    Language of Article: English

    Presenter(s):

    Keywords: avalanche dynamics, seismogram, spectrogram, Hough Transform, speed, evolution

    Page Number(s): 606-610

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