 Satellites detecting movements: SLF researchers measure the slightest shifts in rock, rubble and ice, meaning that a larger number of impending slides, collapses or instabilities of these substances can be detected at an early stage.
 Early warning system for the Himalayas: Scientists help to improve hazard warning maps by training specialists and using cutting-edge simulation software.
 Disaster protection: Satellite and drone data as well as computer simulations based on them help to prevent damage to infrastructure.

Searching for movements via satellite: Radar sensors from space provide important information about where rock or debris is moving, even when this is only by a few centimetres. "This can already be an indication of impending instability," says Yves Bühler, Head of the Alpine Remote Sensing research group at the WSL Institute for Snow and Avalanche Research (SLF). His team is looking for precisely those areas where there is the risk of a landslide, rockslide or ice avalanche.
This is a demanding task for the research group, as the information provided by Bühler and his team will provide the basis for overhauling India's system of hazard indication maps. The aim is to raise the standard of such maps to a level similar to that in Switzerland. The Swiss Agency for Development and Cooperation (SDC) is supporting the project with CHF 230,000 and field personnel. "For the SDC, this cooperation makes a vital contribution to protecting Himalayan mountain communities from natural hazards, which are on the increase due to climate change and particularly hit the poorest and most vulnerable. Thanks to Swiss expertise, a strong basis is being created for the further dissemination of the method in the Himalayas and other mountainous regions," says Riccarda Caprez, project manager at the SDC and programme officer for climate adaptation and disaster risk reduction.
The researchers use a combination of remote sensing via satellite and drones as well as the Rapid Mass Movement Simulation (RAMMS) software developed by the SLF, specifically the module for simulating rock/ice slides. This enables the team to simulate a wealth of processes based on data from space. "In this way, we can forecast where something might happen; this could be soon or might not materialise for 10,000 years," explains Bühler.
In late November 2024, he and three colleagues travelled to Uttarakhand in India, where they trained local experts in how to use the software and create hazard assessments for their region.
The demand was huge. It was expected that 20–30 people would want to participate in the three-day course, but the actual number was more than twice that. This should come as no surprise, as it was only a few years ago, in 2021, that the Chamoli disaster brought tragedy to the region. Bühler describes this as an extreme cascade event, in which rock covered with glacial ice fell from a height of 6,000 metres above sea level, carrying further ice and water-saturated debris into the valley. From there, the mass continued its advance as a mud-debris avalanche. On its way, this mixture of different materials destroyed, among other things, two hydroelectric power plants. Around 200 people died or are still missing.
An operational early warning system and information about which areas were at risk could have prevented a lot of this. As a result, there is also great interest in better methods among policymakers in India. Meanwhile, the operators of hydroelectric power plants in the mountainous region hope that the work of the SLF scientists will provide them with more detailed information on the current situation and potential hazards facing their plants and planned projects.
The SLF researchers are seeking to provide such information. They use the RAMMS software to simulate selected processes. "With the new methods and carefully designed scenarios, threats like the one in Chamoli could in the future perhaps be identified in time and the infrastructure could be better planned and protected," says Bühler. The combination of remote sensing and modelling should make it possible to detect similar instabilities earlier and to better prepare the authorities and local residents for them, for example by providing them with up-to-date hazard maps.
The researchers are reaping the rewards of the new generation of radar sensors on board modern satellites. "These now allow shifts in the earth's surface to be recorded and measured from space at a high spatial and temporal resolution," says SLF scientist Andrea Manconi. The advantage is that the satellites also provide data from remote, inaccessible areas, even in bad weather. Manconi's project, in which he simulates potential dangers, will run until the end of 2025. He is basing this work on his findings from the rockslide in Brienz in the canton of Grisons: "We've successfully tested and validated our methods in the Swiss Alps and can now also apply them in the Indian Himalayas."
An example of this can be found in the Patalganga Valley near Joshimath in the district of Chamoli in the Indian state of Uttarakhand. There, Manconi identified a major landslide using radar satellite data. If this were to accelerate and slide rapidly, it could dam the river, as probably happened in 1970. Manconi describes the worst-case scenario as follows: "In the monsoon season, when there's a lot of water, the dammed lake could break its banks and form a large mud and debris avalanche which would destroy the hydroelectric power plants and villages downstream." SLF researchers are now monitoring this landslide from space in order to detect any acceleration in good time.