This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: On the morning of Aug. 26, a section of mountain near Langtang Lirung peak in Nepal suddenly collapsed. A huge mass of rock, ice and debris plunged roughly 1,200 meters (3,900 feet) into the valley below, producing a highly destructive flood on the Lhende Khola river.
The flow traveled almost 100 kilometers (60 miles) downstream, washing away villages and bridges. Nearly 1,000 people died, and thousands more are still missing across the Nepal–China border. At first, it looked like a glacier collapse.
But emerging satellite and photographic evidence suggests a more complex picture—an avalanche of rock and ice rather than a simple glacier collapse. The mountain face now has a sharply defined scar after the collapse, clearly marking the boundary between the remaining slope and the section that failed. This isn't the first rock-ice avalanche in the Himalayas, but it is by far the most devastating.
Unfortunately, it is unlikely to be the last. Rising temperatures due to climate change mean the permanently frozen slopes of mountains in the region may begin to melt and destabilize. The steep mountain face was topped by a glacier—a heavy river of ice.
It's likely that the steep slope of bedrock collapsed first, followed by the overhang of ice. As this enormous mass fell into the valley, it created a tremendous amount of energy. This would likely have melted the ice in the avalanche and any ice in the valley, adding large volumes of faster-moving water to the flow and intensifying the debris flood.
The rugged Himalayan terrain made the disaster even worse by providing a steep, confined pathway that accelerated the mass of water, rock, dirt and ice as it flowed into the river. A landslide followed the first collapse, and a small lake has formed within the newly created depression in the valley. The site will remain unstable for some time.
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