Chinese authorities have identified a collapsing glacier as the cause of a massive mudslide that struck the China-Nepal border region on August 26. The glacier, located on Nepal’s Langtang Lirung mountain at an elevation of 5,200 meters, fractured around 10:52 a.m., releasing a vast mass of ice, rock, and debris that rapidly descended more than one kilometer. This avalanche of material, equivalent in size to over 60 football fields and moving at speeds comparable to a high-speed train, transformed into a destructive mudslide as it swept through the Himalayan valleys.
Within seven minutes, by 10:59 a.m., the mudslide reached Gyirong Port on the Tibetan side of the border, which sits at approximately 1,800 meters above sea level. Video footage captured at the port showed numerous people fleeing to escape the oncoming torrent. The mudslide devastated approximately 0.7 square kilometers of land, destroying 27 structures and cutting off roads, electricity, and telecommunications to the border area, according to Su Pengcheng, a researcher from the Chinese Academy of Sciences who has been investigating the disaster.
Su noted that the steep vertical drop of the glacier generated significant potential energy, while friction and rock collisions produced enough heat to melt additional ice, increasing the volume of the mudslide. The narrow valley through which the avalanche traveled further accelerated its momentum by mixing water with loose debris downstream.
Authorities have attributed the glacier collapse in part to the long-term impacts of climate change, which they say destabilized the glacial terrain. Su described the event as indicative of "a new and prominent" pattern of disasters involving glaciers and frozen landscapes across the Tibetan Plateau and surrounding regions.
The human toll from the disaster is significant, with at least 16 confirmed fatalities and 546 individuals reported missing. Among those unaccounted for on the Chinese side are 261 foreign nationals from 23 countries, including six Australians. The Australian government has confirmed that 42 of its citizens remain missing. More than 2,100 rescue personnel have been deployed to the area, but operations are complicated by the destruction of the main access road to Gyirong Port and by the formation of dangerous barrier lakes caused by the mudslide.
The largest of these newly formed lakes is dammed by debris roughly 60 meters high, stretching 1.1 kilometers in length and 300 meters wide, containing an estimated 2.2 million cubic meters of water. Officials report that the outflow from the lake currently exceeds the inflow and assess the immediate risk of a dam collapse as relatively low. However, Su warned that large amounts of unstable glacial debris remain upstream, posing ongoing risks of additional mudslides that could endanger both rescue efforts and nearby communities.