Oeschinensee and Kandertal landslides

On the other hand, such landslides can generate spectacular landscapes,[1] such as the glaciated terrain around Oeschinen Lake in Switzerland which has drawn tourists since 150 years and is now part of the Jungfrau-Aletsch protected area.

[2] Climate variations can cause slope instabilities and with global warming scientific interest in large collapses of mountains has risen.

[5] Oeschinensee is situated in the Bernese Alps,[6] within a 5 kilometres (3.1 mi) long side valley of the Kandertal, and lies at about 1,578 metres (5,177 ft) elevation.

It receives inflow from glaciers and springs, while its waters eventually seep through landslide debris although in the past (before a small dam was built) the lake periodically overflowed.

[12] During its later stages, the northern part of the landslide incorporated wet sediments from the Kander valley and began to collapse, forming extensional features such as the ridges at Blausee.

[18] The Fisistock collapse area forms a box-shaped depression, whose western headwall reaches 0.5 kilometres (0.31 mi) height while the eastern one is less conspicuous.

[25] More recent research in 2020 however implies that it actually occurred 3,210±220 years ago, at a time where a change on climate and an expansion of glaciers in the area of the landslide was taking place.

Lake sediments indicate the occurrence of a large earthquake about 3,300 years ago, which, while not necessarily directly causing the landslide, may have destabilized the slopes that later failed.

[8] It detached from the northwestern flank of the Doldenhorn mountain,[17] reached the valley floor after about 20 seconds with a speed of about 65 metres (213 ft),[27] where it was deflected by an earlier landslide deposit (probably from the Kandertal event).

Debris from the landslide covers an area of 1.1 square kilometres (0.42 sq mi) at the outlet of Oeschinensee and may extend below the lake surface.

[29] How the landscape looked like before the collapse is unclear[30] but a volume of 0.046 cubic kilometres (0.011 cu mi) has been estimated on the basis of plausible reconstructions both of the source area and the landslide deposit.

[2][16] The increased instability observed in summer 2018 led to an investigation of the detachment area, with drilling, satellite mapping and the installation of telemetry devices among other responses.