Nepal floods: Before-and-after satellite images reveal scale of destruction

Shugar said the bedrock failure carried a massive chunk of ice with it, sending boulders and debris into the steep valley below. As the material moved downstream, melting ice added water to the flow, creating a powerful mixture of mud, rock and water that swept through settlements.

Trishuli River widened as debris buried villages

The impact was visible in before-and-after satellite images of areas including Kolpurtar, Betrawati and Syapru Besi. The Trishuli River has become significantly wider in places after overflowing its banks and carrying huge amounts of sediment and debris. Its water, which previously appeared greenish, turned brown and black because of the large volume of mud being transported downstream.

Several towns and villages along the river have been devastated, with homes and other structures submerged under mud and debris. In Betrawati, only parts of some houses remain visible in satellite imagery. Buildings were also toppled or swept away in Syapru Besi, a popular tourist destination and starting point for the Langtang trek.

Mountain geographer Alton Byers of the University of Colorado Boulder described the destruction as a wasteland that could take years to recover. He said the event was the largest glacier-related flood he had witnessed.

Scientists are also examining whether climate change played a role. Byers said rising temperatures are melting glaciers and permafrost, potentially weakening the rock, ice and soil that stabilise high-altitude slopes.

However, Cook and Shugar cautioned that there is currently no definitive evidence directly linking this specific collapse to climate change. Cook noted that landslides and slope failures can occur naturally, although a warming climate could make such events more likely by destabilising mountain terrain.

The disaster has killed hundreds of people in Nepal and Tibet, with thousands still missing, including foreigners and pilgrims. Rescue teams continue to search the affected valleys as authorities monitor new lakes and other risks created by the collapse.