Nepal's worst flood disaster in decades began when a glacier collapsed on a Himalayan peak. How high up did the glacier break away?
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17,000 ft
A glacier collapsed 17,000 feet (5,200 meters) up Nepal's Langtang Lirung, triggering an avalanche and flash flood that traveled 14 miles (22 kilometers) to the valley floor in under seven minutes at 120 mph (193 km/h). The debris dammed the river below before giving way, and rivers rose 30 feet (9 meters) in half an hour. More than a thousand people are confirmed dead and thousands more are still missing.
The debris avalanche was so massive it registered worldwide as a magnitude 5.2 seismic event. That reading was not a triggering earthquake, but global seismometers picking up the shockwave of the mountainside collapsing and slamming into the valley floor.
A glacier collapsed at 17,000 feet in Nepal, triggering a 120-mph avalanche and flash flood that killed more than 1,000.
Source: Scientific American / USGS, Aug 2026 (quoting geoscientist Jakob Steiner) · checked Aug 2026