A huge portion of a glacier in the Swiss Alps has broken off from the mountainside, sending rock, mud and ice crashing onto the village of Blatten.

Authorities have been warning of a potential collapse of the Birch glacier for weeks now as cracks appeared in the ice. Earlier this month, villagers and livestock were evacuated from Blatten, which sits in the valley below the glacier and is home to around 300 people.

Webcam and drone images from 28 May show enormous plumes of dust billowing into the Alpine valley as the glacier collapsed, with a huge wave of mud and boulders covering the hillsides and most of the village.

There are no reports of casualties, although one person has been reported missing, according to a press conference held in a neighbouring village on 28 May. The village of Blatten is now largely buried under rubble. The glacier collapse caused an earthquake measuring 3.1 on the Richter scale, according to seismic data.

Images from the site suggest that in addition to the village, huge swathes of forest have also been destroyed and debris has blocked the nearby Lonza river, increasing the risk of flooding to the area.

“Nature is stronger than man. The mountain people know that. But today we experienced an extraordinary event. The event has left us speechless, and it’s shocking to see the images,” said Federal Councillor Albert Rösti during the press conference, according to the Swiss outlet Blick.

Glaciers in the Alps are becoming more unstable as global temperatures rise. In Switzerland, glaciers lost 10 per cent of their volume between 2022 and 2023 alone, official statistics show.

Melting glaciers can cause rockfalls, rock and ice avalanches and debris flows into the valleys below. Research suggests small rockfalls and landslides are increasing in the Alps due to climate change.

However, more investigation will be needed before it will be possible to explain exactly what happened at Blatten, says Mylène Jacquemart at ETH Zurich in Switzerland, including examining how much of the glacier broke off, and why. “Clearly, events like the one in Blatten – at this point a complex process cascade – are incredibly rare, and so quantifying the changes to them is no easy feat,” she says.

Detecting changes in the frequency and severity of huge landslides is tricky, Jacquemart adds.

“The changes that climate change is inducing in high mountain regions (more meltwater, less snow cover, warmer temperatures, more precipitation falling as rain rather than snow) are not favourable for rock stability,” she says. “But, would this have happened without climate change? Quite possibly so. The fundamental question for hazard management is whether there is a significant shift in how often certain events happen. Does an event that has happened every 10 years suddenly happen every year? At this point, we don’t see a clear shift (yet) for such large events.”