On Wednesday 28 May 2025, at around 3:30 pm, a large portion of the Birch Glacier, estimated at around 3 billion cubic metres, collapsed into the Lötschental valley destroying most of the village of Blatten. The landslide triggered a jolt equivalent to a 3.1 magnitude earthquake.
Click here to view a video of the landslide, filmed by Henzen Hans, a local resident who posted the video on Facebook. More videos and images can be viewed here on the SRF website.
But what caused the catastrophic landslide?
Hans Rudolf Keusen, a veteran Swiss geologist who has been studying the dramatic events unfolding above the village of Blatten told broadcaster SRF that a glacier collapse triggered by a massive rockfall from the Kleiner Nesthorn was the cause. The rockfall compressed the glacier, pushing it out of equilibrium, he said.
Such an event is unprecedented in Switzerland, said the expert. Historical landslides—such as those that destroyed Goldau or Elm—have buried villages before. But this combination of ice and rockfall, as seen in Blatten, is unprecedented.
Matthias Huss, a glaciologist at ETH Zurich agrees with Keusen. Heavy rock falling onto the glacier, combined with melting ice, set off a chain reaction.
Ice and water act as a lubricant, seeping between layers of debris. When intense pressure is applied, it becomes a highly mobile, destructive mass. The water saturated material formed a dense slurry that travelled far and buried everything in its path, said Huss.
Is climate change to blame? Huss was cautious. It is difficult to attribute this specific event directly to climate change, he said. However, the increasing frequency of high-altitude landslides in recent years—such as at Piz Cengalo and Piz Scerscen—suggests a broader trend.
The immediate concern now is flooding. The landslide has blocked the flow of the Lonza River and water is building up. Experts are concerned water could suddenly break through, triggering a flash flood.
By Friday afternoon, the water had started to cut a path through the debris, attenuating the build up. However, the situation remains tense.
A total of 365 village residents were evacuated. These people will need to remain outside the zone for the time being, said officials.
More on this:
SRF article (in German)
For more stories like this on Switzerland follow us on Facebook and Twitter.
