Item: The avalanche winter 1999 in switzerland - an overview
Title: The avalanche winter 1999 in switzerland - an overview
Proceedings: Proceedings of the 2000 International Snow Science Workshop, October 1-6, Big Sky, Montana
Authors: Christian Wilhelm, Thomas Wiesinger, Michael Brundl, Walter Ammann Swiss Federal Institute for Snow and Avalanche Research SLF, Davos Switzerland
Abstract: February 1999 will be known in Swiss natural disaster history for its record quantities of snow, for more than 1300 harmful avalanches, 17 deaths, cut-off valleys, blocked transport routes, and for total damage costs of over 600 million Swiss francs. Three intensive snow fall periods accompanied by stormy north-westerly winds brought over 5m of new snow within one month to the northern side of the Swiss Alps. This amount of new snow in 30 days has a periodicity of approximately 80-100 years in the central northern part of the Swiss Alps and 40 - 50 years in the other parts of the Swiss Alps. A comparable catastrophic avalanche period of similar size dates happened only in 1951, where 98 people were killed. The avalanche winter 1951 was the beginning of modern avalanche defense measures for the next five decades in terms of paravalanche constructions, avalanche hazard mapping, avalanche warning and silvicultural measures to maintain the protection forest. Considering the growth in public and private investments in mountainous areas, the enormous increase in mobility of the people and the exponentially rising communication needs over the last fifty years, these large investments in avalanche protection measures over the last 50 years have paid off. The paper presents an overview on the weather, snow and avalanche conditions, the direct and indirect damages caused by avalanches and discusses the effectiveness of the integral avalanche protection measures. Finally the necessary improvements for a future integral avalanche risk management are pointed out.
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Keywords: avalanche disaster, avalanche catastrophy, avalanche damages, insurance, integral risk management, avalanche warning, hazard mapping, paravalanche constructions
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