Item: Weiterentwicklung der strategischen lawinenkunde - ein diskussionsbeitrag
Title: Weiterentwicklung der strategischen lawinenkunde - ein diskussionsbeitrag
Proceedings: International Snow Science Workshop, Davos 2009, Proceedings
Authors: Eike Roth, Klagenfurt, Austria
Abstract: The average risk to get involved into an avalanche on ski tours is 1:10000. At level 1 (European risk scale) it is smaller, at level 5 in a steep slope it probably is close to 1. The range from low to high risks seems to be at least 3 magnitudes. This contrasts sharply to the risk increase by a factor of 2 per risk level (factor 16 from level 1 to 5), as it is presumed in strategic avalanche scoring systems (e. g. “Reduction Method”). Evaluations of data sets from Austria and Switzerland show a minimum risk increase by a factor of 4 per risk level (256 from level 1 to 5). A factor of 2 would result only at highly unrealistic assumptions regarding the relative number of ski tours at different risk levels. The factor 2 per risk level is generally based on examinations of the snowpack. Areas with weak mechanical strength double per risk level, and the risk is thought to be proportional to the likelihood of hitting such an area when skiing. But if the probability of releasing an avalanche in case of a hit increases with the number of weak areas too, the risk gradient must be steeper. There are several potential causes for an increased probability, e. g. enhanced crack propagation at increased numbers of weak areas. The analyzed data sets support a steeper gradient. Conditions are identified where a steeper gradient is risk determining, and possibilities of integrating it into decision strategies are discussed.
Keywords: klassische lawinenkunde, reduktionsmethode, risikopotential, unfallhäufigkeit, risiko
Subjects: klassische lawinenkunde
Digital Abstract Not Available