International Snow Science Workshop Proceedings - Montana State University Library

Item: Infrasonic Monitoring of Snow Avalanches in the Alps

• • Title: Infrasonic Monitoring of Snow Avalanches in the Alps

    Proceedings: Proceedings, 2012 International Snow Science Workshop, Anchorage, Alaska

    Authors:

    • Ulivieri G.  [ Dipartimento di Scienze della Terra, Università di Firenze, Via la Pira 4 50121 Firenze, Italy ]  [ Item srl, Italy (www.item - geophysics.it) ]
    • E. Marchetti  [ Dipartimento di Scienze della Terra, Università di Firenze, Via la Pira 4 50121 Firenze, Italy ]  [ Item srl, Italy (www.item - geophysics.it) ]
    • M. Ripepe  [ Dipartimento di Scienze della Terra, Università di Firenze, Via la Pira 4 50121 Firenze, Italy ]
    • I. Chiambretti  [ AINEVA, Trento, Italy ]
    • V. Segor  [ Regione Autonoma Valle dʼAosta, Italy ]

    Date: 2012

    Abstract: Validation of risk assessment of snow avalanches requires to identify the occurrence of avalanches. For this purpose, after a pilot experiment in Gressonay during the 2009-2010, in December 2010 we installed a permanent 4-elements, 140 m aperture, infrasound array in the Ayas Valley (Italian Alps) where natural avalanches are expected and controlled events are performed. The array consists in high sensitivity (10-3 Pa, 0.5-50 Hz) infrasonic sensors and a 4 channels, 24bits, A/D converter sampling at 100 Hz. Timing is achieved with a GPS receiver. Data are transmitted to the Department of Earth Sciences of the University of Firenze, where are recorded and processed in real-time. A multi-channel semblance analysis is carried out on the real-time infrasonic data set as a function of slowness, backazimuth and frequency content in order to detect all the possible signals. The results gained during 3- years-long test indicate that small-to-medium size powder avalanches can be detected in the short-tomedium range (<5 km). Despite array analysis allows to discards many natural (microbarom, earthquakes) and artificial (airplane, explosions) sources of infrasound, a network of 3 arrays will be deployed on Summer 2012 for a precise and automatic source location, which should allows a better discrimination between “noisy” and avalanches sources of infrasound. Precise location together with real-time monitoring automatically will provide information on potential sectors where avalanches might have occurred during the last 24h, thus providing crucial and reliable information for improving risk assessments.

    Object ID: issw-2012-723-728.pdf

    Language of Article: English

    Presenter(s): unknown

    Keywords: infrasound array network, snow avalanche monitoring, risk assessment

    Page Number(s): 723-728

    Subjects: risk assessment infrared thermography spot size

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