An ice and debris avalanche completely destroys the Valais mountain village of Blatten.
Blatten, a mountain village in the Lötschental valley, is no more. It lies buried under up to 100 metres of landslide, an estimated volume of ten million cubic metres of which thundered down the valley on 28 May 2025. The parts of the village that weren’t buried were flooded in the days following the avalanche, as the wall of debris blocked the Lonza river. Blatten’s destruction has shaken Switzerland, due to the scale of the natural disaster, the unprecedented way it happened and the questions it raises about the long-term habitability of Alpine regions.
Two weeks prior to the disaster, there were growing signs of a potential landslide: the slope of Kleines Nesthorn mountain – which was 3,342 metres high prior to the catastrophe – started to move and crumble. This caused debris and rocks to fall onto the Birch Glacier below, which had been under observation since 1993 as it was unstable. Following an initial, smaller flow of debris but mainly in response to the sustained movement of the rocks and the glacier, the authorities ordered the evacuation of Blatten on 17 May. The severity and dynamics of what subsequently occurred had never been seen before in the Alps: the fallen debris and rocks exerted so much pressure on the glacier that they caused an increasing amount of snow to melt. This caused the entire glacier to slide more and more quickly within just a few days, until it was moving up to ten metres a day.
On 28 May in the afternoon, a big chunk of the Birch Glacier together with the rocks and debris on top of it broke off and fell down the mountain, ultimately burying and destroying the village of Blatten. Rescue work, such as pumping the lake that arose from the water being blocked by the huge volume of debris, was initially impossible. For a start, there was a risk that several hundred thousand cubic metres of rock could still break off from the Kleines Nesthorn. Moreover, the momentum of the avalanche had carried it up the other side of the valley and there was a risk of it falling back into the village. By the time this edition of “Swiss Review” went to press, there was no way of telling how the event would end. The post-mortem regarding what caused the mountain to collapse has also only just begun. The experts basically agree that the event was connected to climate change, but the extent to which individual factors played a part – such as the thaw of the permafrost zone above the glacier or the glacier melting itself, which destabilised it from the mountainside – remains unclear.
www.swissinfo.ch is providing regular updates on the ongoing developments in the Lötschental valley (search term: Blatten)
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Comments :
This is heart breaking! Thank God the village was evacuated!