Danger of rock and glacier falls in the European Alps

If a rock or glacier breaks away from the mountainside, it can cause enormous destruction. One example is the Blatten landslide in the Swiss canton of Valais in May 2025. At that time, large amounts of rock and ice fell from the Birch glacier into the valley and buried 90 percent of the area.

A recent example is the flash flood in the Himalayas. The huge flood rolled down from a height of 5,000 meters into the valley between Nepal and China. It claimed around 900 victims along the way. More than 3,000 people are missing.

There is a mechanism behind such flash floods: If a piece of rock or glacier breaks away, it falls down into the valley and can take the glaciers above it with it. If such a river is blocked by rubble and rock, a lake is formed. The water is building up and the danger of a flash flood of stone, water and earth is growing.

But how likely is such an incident in the European Alps? “Similar events can also occur in the Alps,” says Jan Bag to the “Science Media Center”. He is Professor of High Alpine Cryosphere at the University of Innsbruck.

Scientists have been studying how the glaciers in the Alps are changing for years. “The combination of large rock and glacier avalanches is also known from the Alps,” confirms Michael Bründl. He is actively researching the topic at the WSL Institute for Snow and Avalanche Research (SLF) in Switzerland.

However, the height differences in the Alps are significantly smaller than in higher mountains such as the Himalayas. Therefore, the extent of potential destruction is significantly smaller.

Rockfalls have existed since time immemorial. They are often announced by suspiciously shaped rocky slopes or glacier movement. Experts usually monitor such areas in order to evacuate people or close off areas hours or days before a possible event.

"Fortunately, large cascade events have so far rarely occurred in the Alps. Estimating the probability of such events is extremely difficult or even impossible," adds Bründl.

But what causes such rock and glacier falls? Higher temperatures cause permafrost and ice in crevices to melt. Permafrost is considered the glue that holds the mountains together in their formation. If the permafrost melts because the outside temperature is too warm, parts of the rocks risk breaking apart.

“The temperature in Switzerland has risen by around 3.0 degrees Celsius above the pre-industrial average since measurements began and is therefore warming around twice as fast as the global average, which accelerates the effect in the Alps,” says Bründl. Liquid water usually plays a significant role in triggering ice and rock falls. In general, several factors contribute to this.

Climate change is not solely to blame. In addition, no one has yet specifically researched the influence of climate change on such rock and glacier falls. “The effects of climate change are involved in and accelerate extreme events, together with basic tectonic-geological conditions and factors,” says Bründl.