15 April 2019
Flüela Wisshorn: a large rockslide in the Alps on 18th March 2019
On 18th March 2019, late in the night, a large rockslide occurred at Flüela Wisshorn in the Swiss Alps. The best image of the landslide can be found in a good, detailed article about the event on the Tages Anzeiger website (the article is in German, but Google Translate does a good job):-
This rockslide has been investigated by the WSL Institute for Snow and Avalanche Research (SLF), and some of their initial findings are described in the article in Tages Anzeiger. The Flüela Wisshorn rockslide occurred shortly after midnight, meaning that there were no people at risk, with a volume of about 250,000 cubic metres. Images from the site suggest a failure on an existing defect in the rock mass; interestingly the rockslide scar extends to the ridge:-
Whilst most of the debris has had a comparatively limited runout (and it is interesting to see how much material remains on the steeper parts of the slope), a portion of the landslide has traveled a significant distance. This image, via Deutscher Alpenverein, is a rather beautiful illustration of that:-
The article in Deutscher Alpenverein notes that lowest part of the track seems to have the characteristics of a snow avalanche (with some debris content), rather than a rockslide. The timing of the rockslide is quite interesting, occurring in the latter part of winter and at night. I have no doubt that SLF will investigate this event further, and will be interested to read their conclusions on triggering in due course.
Thanks to Axel Volkwein for highlighting this event.