June 10, 2025
These two satellite images taken on September 19, 2024 and May 29, 2025 show the town of Blatten before and after being almost completely buried in a landslide after the collapse of the Birch Glacier, in the Swiss Alps on the afternoon of May 28, 2025.
Blatten is located 1,542 m above sea level in the Lonza River valley in the canton of Valais, southwest Switzerland. Authorities have reported the landslide made up of rock, ice and water, is several dozen meters thick and approximately two kilometers long. According to data from the Swiss Federal Institute of Technology (ETH), it took just 40 seconds for the rock-ice avalanche to reach the valley floor, equaling an average speed of around 200 km/h. The debris sitting in the base of the valley has interrupted the flow of the Lanza River, causing a lake to form. This is causing additional damage to the already devastated infrastructure of Blatten.
One person was reported missing after the landslide while the rest of the town was able to evacuate days earlier thanks to frequent monitoring and prior warning. Researchers from the ETH say the magnitude of the glacier collapse is unprecedented for the Swiss Alps.
The exact multifactorial causes have yet been comprehensively investigated or confirmed. But according to the Swiss National Centre for Climate Services, human-induced climate warming has led to widespread glacier melting and permafrost thawing in the Swiss Alps, impacting changes in snow cover, streamflow, the timing of snowmelt and increasing the rate of heavy precipitation. Swiss alpine glaciers have lost about 60 percent of their volume since 1850 according to their latest climate report.
CREDITS:
2024 – Esri, DigitalGlobe, GeoEye, i-cubed, USDA FSA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo, and the GIS User Community
2025 – Planet Labs
