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Rock slope failure and avalanche on the Flüela Wisshorn: a chain of processes

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On the night of 19 March 2019, almost a third of a million cubic metres of rock crashed down from the Flüela Wisshorn near Davos. As a result, a very large snow avalanche broke loose that almost flowed onto the closed Flüela Pass road. Little is yet known about such chains of
natural hazard events – in this case, slope failure followed by an avalanche. This is why researchers at SLF are intensively studying such linked processes as part of the “Climate Change and Alpine Mass Movements” programme.

The aim is to understand the processes in more detail and then simulate them on the computer so that protective measures can be adapted accordingly. The Flüela Wisshorn incident provided an interesting case study for the researchers to analyse in detail using seismic measurements and drone images.


Robert Kenner, a permafrost researcher at SLF, sums up the results of the analysis: “The release area of the rock slope failure is located in permafrost. However, the slope failure was probably mainly due to the geological structure of the rock and the erosion of the slope foot through glaciation during the last Ice Age.” The mixture of falling snow and rock landed on an existing rock glacier. The researchers are now curious to see whether the movement of the rock glacier will change in coming years due to this additional mass.

The Flüela Wisshorn event and some comparable rock slope failures in past winters show that such slope failures of this size are not only possible in summer, but at any time of the year.
(Martin Heggli, Diagonal 2/19)

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