Blatten

In May 2025, repeated rockfalls from the ridge above piled millions of tonnes of debris onto the small Birch Glacier above Blatten. The glacier began to move faster under the load.

On 19 May authorities ordered the village evacuated within two hours. About 300 people left with their livestock.

On 28 May, at around 15:30, the glacier collapsed. The avalanche of ice, rock and mud buried about 90% of Blatten and dammed the river Lonza, creating a lake behind the debris. The event registered as a magnitude 3.1 earthquake. A 64-year-old man who was outside the evacuation zone died.

The collapse was a cascade: permafrost and rock failure loading a glacier, the glacier failing, and the debris damming a river. Such chains are a growing concern in a warming Alps.