A glacial collapse in the Himalayas triggered devastating floods across the Nepal-Tibet border region, killing at least 273 people with nearly 1,400 still missing. The disaster swept away entire villages, destroyed bridges and roads, and left communities on both sides of the border searching through debris for survivors.
Scientists have determined that a glacier collapse, rather than an earthquake as initially reported, caused the catastrophic flooding. The U.S. Geological Survey confirmed the seismic event registered as a magnitude 5.2 on the Richter scale and was actually a glacial collapse and debris flow. Satellite analysis showed a 0.2 square kilometer chunk of ice collapsed vertically about 1.2 kilometers, breaking off from a glacier at approximately 5,200 meters elevation and crashing onto the valley floor 1,200 meters below.
The collapse released a torrent of mud, water and ice into the Trishuli river, also known as the Bhotekoshi, which flows between China and Nepal. Water levels in the river rose as much as nine meters in just half an hour, according to experts at the Kathmandu-based International Centre for Integrated Mountain Development. The Lhende Khola river, a tributary of the Bhotekoshi, was particularly affected by the surge.
Officials reported that 403 people are missing in Nepal, including 341 foreign nationals from countries including India, the US, UK, Australia, South Korea and Malaysia. In Tibet, China's state broadcaster said at least three people were killed with 265 missing. Many of the missing are tourists and pilgrims traveling through the mountainous region popular with trekkers.
Satellite imagery revealed that unusually warm weather preceded the disaster. A geomorphologist at the University of Calgary noted that some glaciers in the valley had been covered in snow the day before but were mostly bare ice by the time of the collapse, suggesting significant melting occurred in the 24 hours prior to the event.
While a glacial collapse clearly triggered the flooding, an international group of glacier researchers said it was "unlikely to be the sole cause." Scientists are investigating whether construction in the area may have been a contributing factor, and whether the collapse involved the whole mountainside or was isolated to the glacier itself.
The disaster highlights growing concerns about glacier stability in the Himalayas, where the region is warming twice as fast as the global average. The United Nations reported in 2023 that Nepal's mountains lost close to one-third of their ice in just over 30 years. Between 2011 and 2020, Hindu Kush Himalayan glaciers disappeared 65 percent faster than in the previous decade.
Rescue operations have been complicated by difficult mountain terrain and extensive infrastructure damage. Search teams continue working through valleys and debris fields as authorities in both Nepal and China mobilize emergency response efforts.