Wie kam es zum Flimser Bergsturz?

The Flims landslide is known as the largest landslide in Europe. In 2020, Jordan Aaron (Department of Earth Sciences, Geological Institute, ETH Zurich) took a closer look at the triggering factors for the natural disaster, which occurred about 9450 years ago.

With the help of geological and geomorphological field mapping and modelling, mechanisms were derived that could have triggered the rockfall.  The research team was able to show that the landslide is related to the presence of weak marl-like rock layers. Strong seismic tremors, increased pore water pressure, or a combination of both, eventually reduced strength along the fracture surfaces and triggered the fall of the mountain.

The mechanisms by which this strength reduction occurs are currently poorly understood, but appear to be crucial in explaining the catastrophic failure at Flims as well as many other rock avalanches around the world.

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The exhibition «BergeBeben – BergeStürzen» in the mountain village of Vättis traces the past and present earthquakes and landslides in the World Heritage cantons of Graubünden, St. Gallen and Glarus. The connection between earthquakes, landslides and the formation of mountains, especially the Alps, is also discussed.