Inventory of Hazardous Glaciers in Switzerland

Within the framework of the EU Project GLACIORISK (Survey and prevention of extreme glaciological hazards in European mountainous regions) and a mandate from the Canton of Valais, the Laboratory of Hydraulics, Hydrology and Glaciology (VAW) of the Swiss Federal Institute of Technology in Zurich compiled an inventory of hazardous glaciers in Switzerland. "Glacial hazard" refers to critical glacier fluctuations, glacier floods or ice avalanches. The term glaciers floods includes both glacial lakes and water pocket outbursts. These three types of hazards are closely linked together and, by way of feedback mechanisms can lead to dangerous or even catastrophic events. The present inventory deals with hazards that threaten life in the vicinity of human facilities (e.g. settlements, communication roads, tourist installations). Inherent mountaineering risks are therefore not considered.

The inventory includes 82 glaciers which in the past inflicted damage on persons or property or for which a potential danger was recognized. Of these, 55 are located in the canton of Valais, 18 in canton Berne, 2 in the cantons Vaud, Uri and Grisons, and one in the cantons of Obwalden, Glarus and Ticino, respectively. According to present assessment, for 51 of these 82 glaciers, potential damage to settlements (23 cases), traffic routes (29 cases) or other man-made installations (water intake, farm buildings, agricultural land, hiking trails, mountain cabins, tourist facilities) (50 cases) must be expected within the next 10 to 20 years. A large number of people pursue various activities within the potential risk zone. At present there is a monitoring scheme for only 12 of the 51 glaciers, whereas for the remaining glaciers, such a scheme has still to be devised.

A compilation of all inventoried events showed that since 1595 at least 440 persons have lost their lives in 21 glacial disasters (approx. one event every 20 years, or one victim per year). For 146 events, collateral damage occurred to various human infrastructures (approx. one event every 3 years, Fig. 1).

This inventory contains all the information about glacial events and potential risks we could gather from local chronics, glacier reports, publications and newspapers. It does not claim to be exhaustive, some events may have escaped from the observation, or gone unrecorded. As the hazard potential changes with glacier fluctuations (in the context of potential climatic changes), the results of this present evaluation will have to be revised and updated regularly.