Verhalten abseits der Piste Avalanche accidents Wissenswertes über Lawinen Literatur Kernteam Lawinenausbildung Exceptional avalanche situations
What are the effects of explosions in the artificial triggering of avalanches?
Avalanche control by explosives is a widely used measure for avalanche protection. The pressure wave caused by the explosion (Fig. 1) penetrates the snow pack and can cause an internal weak layer to fracture. This fracture can then lead to the release of an avalanche, provided the snow cover structure is conducive to fracture propagation. Avalanche control is used to secure dangerous slopes threatening ski areas, roads, railway lines and settlements, complementing or replacing permanent and temporary measures such as avalanche defense structures, galleries or long road closures and evacuations. Avalanche control is most often performed with explosives by hand or from a helicopter. However, fixed remotely controlled avalanche control installations have become increasingly popular, due to their safe use in all weather conditions.
What are the processes within the snow cover during avalanche control?
We are especially interested in the processes within the snow cover during an explosion and how far from the explosion an avalanche still is likely to be triggered.
Within this project we will answer the following questions:
Trailing the explosion
Explosions are dynamic processes with very high velocities. To measure the attenuation of the pressure wave with distance we use sensors on and within the snow cover at various distances from the explosion. These sensors consist of high precision microphones and accelerometers (Fig. 2). The tests are performed on a large level field with a spatially homogeneous snow cover (Project Spatial Variability) allowing for reproducible results and to ensure that the sensors are not destroyed by an avalanche.
Using a numerical model, we will simulate the effect of explosions on the snow cover. This will allow us to evaluate where the optimal placing for fixed avalanche control installations is and what the spacing between the installations should be.
The project is mainly supported by the Federal Office for the Environment (FOEN).