Mysterious rock fall in the Winter

"The scale of the event has surprised us," says Martin Heggli from the snow and avalanche research Institute (SLF) in Davos. The rock masses at 3085 meters high Flüela Wisshorn dissolved on the 19. In March, shortly after midnight.

the exact time of The rock fall could be determined on the basis of seismic records of the Swiss seismological service.

The specialists of the SLF were first of all that some tens of thousands of cubic meters of Rock thundered into the valley. After a drone flight over the area showed, however: some 250’000 cubic meters of Rock were loosened from the North-West flank of the mountain. Only by luck no one came to any harm.

The coarse blocky Material deposited in the valley below the Wisshorn summit. Photo: Robert Kenner, SLF,

The rock masses and the resulting slab avalanche buried the a lot of committed backcountry skiing via the winter gap route Wisshorn to the Flüela. "Just imagine, if the rock fall had occurred on a beautiful Saturday morning," says Heggli.

A plaque on the flüela pass road warns hikers to operate this Route. Because there is still loose Rock is located in the summit area, which can solve, especially in warmer temperatures.

Foundation melted off

According to the SLF-specialists rock can falls, even in the Winter occurrence, in such Size, however, they are rare events.

Similar cases there were in February 2014, on the Piz Kesch, and in March 2016 in the Val Strem in Sedrun. In both cases, less of the Rock dissolved, however, when the Flüela Wisshorn: 150’000 cubic meters of the cache, and 225’000 cubic meters in the Val Strem.

The snow avalanche reached up to the closed flüelastrasse down pass. Photo: Robert Kenner

the cause of the event at the Flüela, the geological nature of the mountain. "On the drone images, how to clean the Rock from the mountain solved," says Heggli. According to need to already have before the rock fall, there is a gap existed.

in Addition, the whole slope had been stabilized earlier by a small glacier at the foot of the mountain. This glacier has melted away in the last twenty years. "In order for a previously existing support is missing now," says Heggli.

to learn more about the cause of the rock fall, wait for the experts now the snow to melt, before you make an image.

drones-ortho photo of the rock fall and avalanche Deposit Wisshorn on the Flüela. Photo: Yves Bühler, SLF. Map: swisstopo (tages-Anzeiger.ch/Newsnet)

Created: 11.04.2019, 18:42 PM