Flood waters at the Swiss village obliterated by a glacial avalanche continued to rise by a staggering 80cm (2.6ft) every hour overnight, raising fears that a tidal wave could soon swamp and destroy more nearby communes.

The danger of flooding and further erosion remains high around the Alpine village of Blatten, which saw 90 per cent of the town destroyed on Wednesday when the Birch glacier partially collapsed.

Experts had anticipated a growing lake forming between the debris would start to overflow overnight. At one point on Thursday, water levels in the reservoir were rising at three metres (9.8ft) every hour, Tages-Anzeiger reports, with water still crashing in from the Lonza River.

State Councilor Stéphane Ganzer said the possibility of a massive flood wave rolling down the valley cannot yet be ruled out. Temperatures of 20C (68F) are expected on Friday, heightening the risk of snow melting and adding to the build up.

Fearing the potential overspill, regional command staff have prepared two more local villages for rapid evacuation, announced overnight. Some 2,000 residents of Gampel and Steg have been asked to organise alternative accommodation beyond the valley.

Residents of two downriver villages, Kippel and Wiler, have already been evacuated as a precaution. Blatten, anticipating the glacier collapse, was evacuated in advance, though one person remains missing.

Swiss authorities were on Thursday monitoring for possible flood risk in a southern valley

A satellite image shows the destroyed houses and blocked Lonza River, after a glacier in the Swiss Alps partially collapsed and tumbled onto the village, in Blatten, Switzerland May 29

Soldiers load heavy machinery onto trailers to aid the site of the catastrophic mud slide

Between 19 and 28 May, several million cubic meters of rock fell from the Kleines Nesthorn mountain above Blatten, forming a nine-million-tonne debris cone on the Birch Glacier

One person went missing, and numerous houses were destroyed after a large part of Blatten, which had been evacuated earlier, was buried under masses of ice, mud, and rock

Rescue teams have been looking for the  64-year-old man missing since the landslide. 

But local authorities were forced to suspend the search on Thursday afternoon, saying the debris mounds were too unstable for now, and warning of further rockfalls.

Flooding increased yesterday as the mound of debris almost 2 km (1.2 miles) across clogged the path of the river, causing a lake to form amid the wreckage.

Authorities declared a local state of emergency as they monitor the situation.

‘There is a serious risk of an ice jam that could flood the valley below,’ Antoine Jacquod, a military security official, told the Keystone-ATS news agency.

‘We’re going to try to assess its dimensions today,’ added Jacquod, speaking on Thursday.

An artificial dam was preemptively emptied to receive the water pushed back by the wall of ice, earth and rubble.

The Valais cantonal government has meanwhile asked the army to provide clearing equipment and pumps to secure the riverbed.

This photograph taken above Wiler shows a Super Puma helicopter of the Swiss Air Forces flying next to the rest of the huge Birch Glacier, on May 29, 2025

Tthe Bietschhorn mountain in the Swiss Alps on Thursday, after part of the huge Birch Glacier collapsed the day before

Mud and rocks slide down a mountain after a glacier partially collapsed covering most of the village of Blatten, Switzerland May 28

Hundreds of homes in the Alpine village, normally home to 300 people, were destroyed and one person is currently missing, officials said

The destruction of Blatten village after a massive avalanche triggered by the collapse of the Birch Glacier, Switzerland, 29 May 2025

A satellite image shows Blatten after a glacier in the Swiss Alps partially collapsed and tumbled onto the village, May 29, 2025

‘The deposit … is not very stable, and debris flow is possible within the deposit itself (which) makes any intervention in the disaster area impossible for the time being,’ cantonal authorities stated, adding there was risk on both sides of the valley.

‘The water from the River Lonza cannot flow down the valley because there is an enormous plug,’ explained Raphael Mayoraz, the cantonal official in charge of natural hazard management.

‘The lake behind the debris is getting higher and higher. And the water masses are pressing on the dam. This increases the pressure,’ Christoph Hegg of the Swiss Federal Institute for Forest, Snow and Landscape Research (WSL) told Blick.

‘The worst case scenario is that the load on the dam becomes too great and the dam breaks. The water masses then rush into the valley and, depending on the strength of the material, are likely to sweep the debris with them.’

New images shot from a helicopter above Blatten lay bare the scale of the destruction – and the likelihood that its neighbouring settlements could face a deluge.

The village of Kippel is at a lower risk in the event of a flood as much of the properties are situated further up the banks.

But locals told 20 Minuten that a newly constructed sewage treatment facility and power plant could be demolished.

A campsite that routinely welcomes holidaymakers also lies directly in the path of floodwaters.

Footage showed a cloud of ice and scree pluming as rockfall headed towards the valley following the glacier collapse yesterday

A cow is flown by helicopter from the landslide area near the Bietschhorn in the Loetschental valley to a farm, during evacuations on May 20

Residents and cows were evacuated from the village last week

As the government and emergency services work to avoid another catastrophe, officials and residents of Blatten told of their horror following the disaster that erased their livelihoods.

‘I don’t want to talk just now. I lost everything yesterday. I hope you understand,’ one middle-aged woman from Blatten told a Reuters reporter, declining to give her name as she sat alone disconsolately in front of a church in Wiler.

Chef Herbert Bürgisser, who operated a hotel business in Blatten, told Blick he had planned to renovate the property. ‘Now everything is gone,’ he said solemnly.

‘The unimaginable has happened,’ Blatten’s president Matthias Bellwald told a press conference in the immediate aftermath. ‘We have lost our village, but not our hearts.’

‘Even though the village lies under a huge pile of rubble, we know where our homes and our church must be rebuilt,’ he added.

The initial disaster occurred at around 3:30pm local time on Wednesday when a huge chunk of the Birch glacier broke off.

Christian Huggel, a professor of environment and climate at the University of Zurich, said while various factors were at play in Blatten, it was known that local permafrost had been affected by warmer temperatures in the Alps.

The loss of permafrost can negatively affect the stability of the mountain rock which is why climate change had likely played a part in the deluge, Huggel said.

A general view of the village of Blatten buried under mud and rocks after a massive avalanche triggered by the collapse of the Birch Glacier, Switzerland, 29 May 2025

A car is air-lifted on the day after the huge Birch Glacier collapsed and a massive landslide destroyed the evacuated small village of Blatten in the Swiss Alps, on May 29, 2025

Blatten and its surroundings in the Bietschhorn mountain of the Swiss Alps, Switzerland on May 29, 2025

Swiss authorities were on May 29, 2025 monitoring for possible flood risk in a southern valley, following the massive glacier collapse

The extent of the damage to Blatten had no precedent in the Swiss Alps in the current or previous century, he added.

Swiss glaciers, severely impacted by climate change, melted as much in 2022 and 2023 as between 1960 and 1990, losing in total about 10 percent of their volume.

In late August 2017, approximately 3.1 million cubic meters of rock fell from Pizzo Cengalo, a mountain in the Alps in Graubuenden canton, near the Italian border, claiming the lives of eight hikers.

Some 500,000 cubic metres of rock and mud flowed as far as the town of Bondo, causing significant material damage but no casualties.

In 2023, residents of the village of Brienz in eastern Switzerland were evacuated before a huge mass of rock slid down a mountainside, stopping just short of the settlement.

Brienz was evacuated again last year because of the threat of a further rockslide.