Item: Listening to snow – avalanche detection using a seismic sensor array
Title: Listening to snow – avalanche detection using a seismic sensor array
Proceedings: 2010 International Snow Science Workshop
Authors: Alec van Herwijnen*, Jake Turner and Jürg Schweizer WSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland
Abstract: Data on avalanche activity are of vital importance for avalanche forecasting. Avalanche activity is usually estimated based on visual observations, which are imprecise and impossible at night or when visibility is limited. In recent years various researchers have developed automatic avalanche detection systems to overcome these shortcomings. Over the last three winters we have developed a seismic sensor array to continuously monitor elastic waves in the snow cover on an avalanche slope near Davos (Eastern Swiss Alps). Due to the low frequency and high sensitivity of the sensors considerable background noise originating from the nearby town and ski hills was also recorded. Additional observations methods, such as cameras and a microphone, were installed to characterize sources of background noise. Since the deployment of the first prototype system in the winter of 2008, numerous avalanches have released on slopes nearby the sensor array, and on the instrumented slope itself. This enabled us to determine specific characteristics in the time-frequency representation of seismic signals generated by avalanches. Using this information we developed a preliminary method to detect and characterize the recorded signals, which is of vital importance to remove any signal not related to avalanches. Furthermore, we are also able to distinguish loose snow avalanches from slab avalanches. The seismic sensor array therefore provides objective avalanche activity data for a limited area (i.e. about 1 km2). The development of the sensor array, the signal processing methods as well as a comparison of avalanche activity data with meteorological data from a nearby automatic weather station are presented.
Keywords: avalanche detection, seismic sensor array, forecasting, visual observations