DETECTING AVALANCHES USING SEISMIC MONITORING SYSTEMS

ABSTRACT: Meteorological, snowpack and avalanche activity data provide the essential building blocks for avalanche forecasting. While in recent decades the availability and coverage of meteorological data has dramatically improved, the same has not happened for avalanche activity data. The reason is that data on avalanche activity are generally obtained through visual observations, which are imprecise and impossible when visibility is limited. This leads to large uncertainties in the number and exact timing of avalanches, resulting in rather poor correlations between avalanche activity, meteorological parame-ters and estimated avalanche danger. To improve avalanche forecasting, remote detection of avalanches is therefore required to obtain accurate and near real-time avalanche activity data. Seismic monitoring systems are very well suited for this task and typically rely on one or several sensors in an avalanche track or at valley bottom to detect avalanches. We employ a different approach, consisting of continuously recording seismic signals in an alpine start zone. Avalanches can then visually be identified in the seismic data to obtain an avalanche database. Based on measurements from our field sites above Davos (Swit-zerland), we show how seismic monitoring can provide high resolution avalanche activity data, and how these data can provide new insights into avalanche formation processes. While for large-scale operation-al avalanche forecasting automatic avalanche detection still has to be developed, we will further show that seismic monitoring can already effectively be used to remotely detect artificially triggered avalanches below fixed avalanche control installations