On the afternoon of May 28, 2025, an avalanche of rock and ice from the Birch Glacier (Birchgletscher) in southwestern Switzerland roared into the valley below.
On the afternoon of May 28, 2025, an avalanche of rock and ice from the Birch Glacier (Birchgletscher) in southwestern Switzerland roared into the valley below. Debris buried most of the village of Blatten and dammed the Lonza, causing the river to flood. The event occurred after rock from a crumbling mountain peak built up on the glacier, which likely contributed to its ultimate collapse.
The OLI-2 (Operational Land Imager-2) on Landsat 9 captured this image (right) of avalanche debris in the Lonza river valley on May 29, 2025, the day after the landslide. For comparison, the left image, acquired with the OLI on Landsat 8, shows the same area approximately one year before the slide, on June 19, 2024.
The path of the debris flow descends the southern side of the valley from a peak called Kleiner Nesthorn toward Blatten. The event was so powerful that debris continued as much as 240 meters (790 feet) up the opposite valley wall. Rock and ice from the avalanche extended 2.5 kilometers (1.6 miles) down the valley, damming the river behind it and flooding part of the village.
Read more at: NASA Earth Observatory
Photo Credit: Michala Garrison/NASA Earth Observatory
