Rockfall in Blatten: How drones provide insurers and researchers with an overview

Following the devastating rockfall in Blatten in Valais, the Swiss insurance industry is using drones on a large scale for the first time. The high-resolution images from the earthquake claims organization (SOE) not only show the extent of the destruction, but also help to react more quickly, document damage and draw lessons for the future.

The rockslide that hit the village of Blatten in the Lötschental at the end of May 2025 was not a sudden event. The mountain had already been active for years, explains Prof. Dr. Daniel Farinotti (ETH Zurich/WSL Sion) in the video. “The mountain had been very active in rockfall for years. The rocks covered the glacier below, which advanced as a result. And on this day came the final kick, the mountain moved again massively and transported all the material into the valley.”

The drone images clearly show how large the landslide actually was: the former forest and meadows have disappeared, the landslide path is a vegetation-free swath, a desolate but precise image of the force of nature.

A lake of rubble and water

The images also show a secondary disaster: The huge cone of debris has dammed up the River Lonza, creating a lake. “What you can see on the right are houses that are now standing in the water. These buildings were undamaged by the fall itself, but were flooded because the fall dammed up the river,” says Farinotti.

The consequences are complex: oil tanks rise, heating systems leak, personal belongings are lost. And the question of reconstruction is already coming into focus.

Drones in action – within 48 hours

Conventional damage assessment was no longer possible in Blatten. Parts of the community were cut off from the rest of the valley by the cone of rubble. This is where the earthquake damage organization (SOE) came into play, according to Gabor Jaimes, Dipl. Ing. ETH specialist responsible for natural hazard insurance at the Swiss Insurance Association (SIA ). “After we received the order, we were able to be in the area of operation within 48 hours,” reports Thomas Kühni, Managing Director of SOE. “We flew over the houses with drones, recording facades and roofs so that our client – the natural hazard pool – could quickly assess what the damage looked like and whether immediate measures were necessary.”

The images were then integrated into a web-based interactive map. This enabled insurers and authorities to see at a glance which buildings were completely damaged (marked in red), which were only soiled or slightly damaged (green) and which remained undamaged (yellow).

Digitization of claims processing

This method is not only efficient, but also creates transparency and traceability. Each building is uniquely identified by its EGID code and forms an important basis for insurers to correctly allocate and document damage.

“We can search directly for addresses or EGID on the map, select a building and immediately call up the corresponding photos,” explains Kühni. “For example, we can see whether a roof has debris damage or is just dirty.”

Coordination in the danger zone

The drone mission was only possible thanks to close coordination with the Lötschental regional command staff and air traffic control “We had to coordinate flight operations with Air Zermatt and the army so as not to take any risks,” says Kühni “The safety of the emergency services had top priority.” This cooperation between insurers, authorities, the army and research institutions is now considered exemplary for modern disaster management.

Insurers, research and authorities learn together

The drone data not only provides insurers with precise damage patterns, but is also of great value to scientists and authorities. They help to analyze processes such as debris flows, landslides or debris redistribution and to better plan preventive measures. “The fact that we as an earthquake damage organization can also be used for natural hazards shows that our concept works,” says the SOE manager. “We were able to provide fast, efficient and targeted images and thus make a contribution to resilience.”

Looking ahead: data as a tool for resilience

The rockslide in Blatten shows how technology and insurance practice can come together. The digitalization of damage assessment saves time, protects people and provides valuable insights for reconstruction and prevention.

For the insurance industry, the operation in Blatten marks a turning point: from traditional assessment to data-based, interactive damage analysis and is a model that is likely to set a precedent for natural disasters throughout Switzerland in the future.

Binci Heeb

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