The images of those devastating mudslides which, on 26 August 2026, killed at least a thousand people in Nepal and China, have been seen all over the world. They have, quite rightly, caused alarm, but have also raised many questions, such as whether similar disasters could occur in France.
Precedents in Europe
Events of this kind have already been observed in Europe, although to date they have never reached the scale of that seen in Nepal.
On 28 May 2025, for example, in Switzerland, the Birch Glacier collapsed, triggering torrential mudflows that almost completely destroyed the village of Blatten, situated at an elevation of over 1,500 metres. Fortunately, initial landslides further upstream had already alerted the authorities, who were therefore able to monitor the situation continuously and evacuate the entire village a few days before the collapse. Nevertheless, this event left a deep impression on people, even though the volume of ice and rock involved was 10 to 20 times smaller than that displaced in Nepal.
Prior to that, on 21 June 2024, in Isère, a massive mudslide carrying rock debris devastated the village of La Bérarde. The hundred or so residents were urgently evacuated by helicopter at the time, but since then, none of them have been able to return home.
There are also much earlier instances of this kind of phenomenon, such as in 1892, when a destructive wave hit the Alpine valley of Saint-Gervais, causing 175 deaths.
Behind all these events, there are some similarities: a sudden phenomenon, a very substantial influx of water combined with a debris flow, generating a great deal of energy and potentially causing very significant damage.
A range of scenarios
Glacial and periglacial hazards are linked to the current or past presence of ice and originate at high elevations. The main phenomena that can trigger them are as follows:
- Glacier destabilisation, which triggers an avalanche of ice and debris.
- Water pockets, which form inside glaciers and whose sudden release can lead to significant flash floods.
- Glacial lakes, which are generally formed when glaciers retreat. The potential instability of the lake’s banks can lead to rapid draining.
- Rocky glaciers consist of a mixture of ice and rock debris. Global warming is leading to an increase in their flow rates and, in some cases, to rockfalls that can provide unstable debris.
- The permafrost, the ice which holds the soil and rocks together, can, as it begins to melt, cause a deterioration in the geotechnical behaviour of the rocks and thus contribute to collapses and rock slides. This phenomenon was observed in the summer of 2026 in the Mont Blanc massif at the Aiguille du Midi, and more broadly across the Alps.
Whilst it is still too early to confirm whether climate change has had an impact on this event, one thing remains certain: the unprecedented weather conditions we are facing will inevitably encourage this sort of occurrence.
How can we plan ahead?
To prepare for these events, the first step is to gain a better understanding of the areas at risk. In France, the Plan for the Prevention of Glacial and Periglacial Hazards was launched with this in mind, under the auspices of the Ministry for Ecological Transition. It brings together researchers and technical personnel (from the National Forestry Office’s mountain land restoration department, Météo-France, INRAE, the Conservatoire d’Espaces Naturels, CNRS laboratories, etc.).
The goals of this programme are to:
- strengthen research into the prevention of glacial and periglacial hazards;
- characterise hazards and identify areas at risk, particularly vulnerable mountain lakes;
- manage high-risk sites: predicting such events may involve monitoring various data over time, such as the water levels in intraglacial pockets or glacial lakes, monitoring via satellite imagery, and installing displacement sensors;
- share information and foster a risk-prevention culture.
How can we minimise the risks and damage?
Continual monitoring enables various measures to be taken at an early stage to reduce the risks. Regular drainage of glacial mountain lakes or pockets of water can be carried out in high-risk areas, so as to prevent the sudden collapse of these water reservoirs.
We might also mention nature-based solutions, such as forests and timber structures, which can protect areas against rockfalls. Finally, the severity of the damage depends on spatial planning and urbanisation.
