On Wednesday, May 28, 2025, a massive rockslide at the Birchgletscher triggered a partial collapse of the glacier ice. As a result, several million cubic meters of ice and debris fell into the Lötschental valley and accumulated over a distance of approximately two kilometers. The village of Blatten was largely buried. The masses blocked the course of the Lonza River, causing a lake to form. This lake has since flooded buildings that were previously undamaged. Due to the ongoing water accumulation, there was a risk of overflow and the triggering of a debris flow, leading to the precautionary evacuation of the downstream villages of Wiler and Kippel [1,2].
However, on Friday (May 30, 2025), the water dammed behind the debris cone began to find a path and partially drain, so that, according to the cantonal geologist’s assessment, an uncontrolled overflow is currently not expected [3]. Nevertheless, there remains an acute danger of further rockfalls at the Kleines Nesthorn, where hundreds of thousands of cubic meters of unstable rock are considered at risk of collapse [1,2].
Cleanup operations are currently not possible, as the unstable debris cone is considered too dangerous according to the Natural Hazards Service of the Canton of Valais. Neither rescue workers nor heavy machinery can access the area [2]. The current focus lies on organizational protective measures for the downstream settlements; endangered communities have been evacuated, and a lower-lying reservoir has been partially drained [1].
Crisis management in the Lötschental is proceeding in a coordinated and professional manner. Early warning systems were triggered in time, and geological monitoring was taken seriously. The evacuation, carried out by the municipality of Blatten in cooperation with the Natural Hazards Service of the Canton of Valais, was conducted early and in an orderly manner [4]. The Swiss Red Cross, together with Caritas Switzerland, supported coordination on site and is providing financial resources for emergency aid [5]. Civil protection personnel from Zurich are also expected to assist in Blatten once the Valais authorities and their crisis team communicate what kind of support is needed [3].
As of May 30, 2025, 14:00 CEST
[1] SRF (2025a): Lonza steigt +++ Gampel/Steg sollen sich auf Räumung vorbereiten. Retrieved 30/05/2025 from: https://www.srf.ch/news/schweiz/dorf-blatten-verschuettet-lonza-steigt-gampel-steg-sollen-sich-auf-raeumung-vorbereiten
Tagesschau (2025): Flutwelle oder eine Gerölllawine? Retrieved 30/05/2025 from: https://www.tagesschau.de/ausland/europa/gletscherabsturz-schweiz-100.html
[3] SRF (2025b): Seewasser fliesst ab +++ Überschwappen aktuell nicht zu erwarten. Retrieved 30/05/2025 from: https://www.srf.ch/news/schweiz/bergsturz-blatten-seewasser-fliesst-ab-ueberschwappen-aktuell-nicht-zu-erwarten
[4] SRF (2025c): Blatten: konkrete Gefahr durch Bergstürze, 92 Personen evakuiert. Retrieved 30/05/2025 from: https://www.srf.ch/news/schweiz/loetschental-im-wallis-blatten-konkrete-gefahr-durch-bergstuerze-92-personen-evakuiert
[5] Schweizerisches Rotes Kreuz (2025): Bergsturz in Blatten: das SRK unterstützt die betroffene Bevölkerung. Retrieved 30/05/2025 from: https://www.redcross.ch/de/unser-engagement/news-und-geschichten/drohender-bergsturz-in-blatten-das-srk-bereitet-sich-vor
(Image Source: Tagesschau)