EGU21-16562
https://doi.org/10.5194/egusphere-egu21-16562
EGU General Assembly 2021
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Observing avalanche dynamics with Distributed Acoustic Sensing

Andreas Fichtner1, Pascal Edme1, Patrick Paitz1, Nadja Lindner1, Michael Hohl2, Pierre Huguenin2, Betty Sovilla2, Pere Roig-Lafon3, Emma Surinach3, and Fabian Walter4
Andreas Fichtner et al.
  • 1ETH Zurich, Institute of Geophysics, Zurich, Switzerland
  • 2Swiss Federal Institute for Forest, Snow and Landscape Research, Birmensdorf, Switzerland
  • 3Grup RISKNAT, Institut Geomodels, University of Barcelona, Faculty of Earth Sciences, Department of Earth and Ocean Dynamics, Barcelona, Spain
  • 4ETH Zurich, Laboratory of Hydraulics, Hydrology and Glaciology, Zurich, Switzerland

Avalanche research requires comprehensive measurements of sudden and rapid snow mass movement that is hard to predict. Automatic cameras, radar and infrasound sensors provide valuable observations of avalanche structure and dynamic parameters, such as velocity. Recently, seismic sensors have also gained popularity, because they can monitor avalanche activity over larger spatial scales. Moreover, seismic signals elucidate rheological properties, which can be used to distinguish different types of avalanches and flow regimes. To date, however, seismic instrumentation in avalanche terrain is sparse. This limits the spatial resolution of avalanche details, needed to characterise flow regimes and maximise detection accuracy for avalanche warning.

As an alternative to conventional seismic instrumentation, we propose Distributed Acoustic Sensing (DAS) to measure avalanche-induced ground motion. DAS is based on fibre-optic technology, which has previously been used already for environmental monitoring, e.g., of snow avalanches. Thanks to recent technological advances, modern DAS interrogators allow us to measure dynamic strain along a fibre-optic cable with unprecedented temporal and spatial resolution. It therefore becomes possible to record seismic signals along many kilometres of fibre-optic cables, with a spatial resolution of a few metres, thereby creating large arrays of seismic receivers. We test this approach at an avalanche test site in the Valleé de la Sionne, in the Swiss Alps, using an existing 700 m long fibre-optic cable that is permanently installed underground for the purpose of data transfer of other, independent avalanche measurements.

During winter 2020/2021, we recorded numerous snow avalanches, including several which reached the valley bottom, travelling directly over the cable during runout. The DAS recordings show clear seismic signatures revealing individual flow surges and various phases/modes that may be associated with roll waves and avalanche arrest. We compare our observations to state-of-the-art radar and seismic measurements which ideally complement the DAS data.

Our initial analysis highlights the suitability of DAS-based monitoring and research for avalanches and other hazardous granular flows. Moreover, the clear detectability of avalanche signals using existing fibre-optic infrastructure of telecommunication networks opens the opportunity for unrivalled warning capabilities in Alpine environments.

How to cite: Fichtner, A., Edme, P., Paitz, P., Lindner, N., Hohl, M., Huguenin, P., Sovilla, B., Roig-Lafon, P., Surinach, E., and Walter, F.: Observing avalanche dynamics with Distributed Acoustic Sensing, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-16562, https://doi.org/10.5194/egusphere-egu21-16562, 2021.

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