Monitoring snow avalanches in Grasdalen using an infrasound array

Abstract

The absence of near real-time information about the avalanche activity is a significant challenge for local avalanche forecasting (Schweizer and van Herwijnen 2013). Information about avalanche activity in neighboring paths (“indicator avalanches”) can be critical in understanding the current snow-stability conditions and for evaluating past bulletins (Kristensen 2016). Reliable systems for automatic monitoring of avalanche activity that can supplement visual observations are desirable for event verification and as input for operational forecasting. An infrasound detection of avalanches (IDA) array was maintained in Grasdalen between October 2014 and spring 2019 (Humstad et al. 2016). IDA system is based on technology developed by iTem and Laboratorio di Geofisica Sperimentale of the University of Florence, Italy (Ulivieri et al. 2012). The system is commercialized in Norway by Wyssen Norge AS, which is a subsidiary of Wyssen Avalanche Control AG in Switzerland. The project has been run as a collaboration between the Norwegian Public Roads Administration (NPRA), Wyssen, and NGI.