Assessment of the hazard potential of ice avalanches using remote sensing and GIS-modelling

Ice avalanches typically occur when a large mass of ice breaks off from steep glaciers. Since the reach of ice avalanches is usually low, their hazard potential is generally restricted to high mountain areas that are densely populated or frequently visited by tourists. However, far-reaching disasters are possible in combination with other processes such as rockfalls or snow avalanches. In addition, the hazard potential of ice avalanches is presently increasing as a consequence of climatic and socio-economic changes in mountain areas. Dealing with ice-avalanche hazards requires robust tools for systematic area-wide detection of hazard potentials. Corresponding techniques have not been developed so far. To bridge this methodological gap, a three-level downscaling approach was developed. This method chain is based on statistical parameters, geographic information system (GIS) modelling techniques and remote sensing. The procedure permits to perform a fast and systematic first-order mapping of potentially dangerous steep glaciers and their runout paths for an entire region. To validate the approach, a case study was carried out in the Bernese Alps, Switzerland. The results correspond well with local studies using dynamic avalanche models. Improvements can be obtained by expanding the method chain by including basic data of higher spatial resolution as satellite data and digital terrain models (DTM).