Glacier collapse may have triggered deadly flash flood near Nepal-Tibet border

Kathmandu, Nepal. A deadly flash flood near Nepal’s border with Tibet on Wednesday may have been triggered by the collapse of the lower section of a glacier, according to experts who reviewed Planet Labs satellite imagery. Nearly 170 bodies have been recovered, while about 1,500 people, including at least 700 foreigners, remain missing.

Satellite imagery assessment

Before-and-after images reviewed by Reuters showed a green mountainside buried beneath brown debris and sediment.

Vikram Gupta, an engineering geology specialist at India’s Sikkim University, said a substantial part of the glacier snout had collapsed, likely carrying rock and sediment with it.

Dan Shugar, an earth scientist and associate professor at the University of Calgary, said the images indicated that the lower part of a glacier at about 5,200 metres broke away and fell around 1,200 metres onto the valley floor.

Cause under examination

The cause of the collapse was not immediately clear. Nepali officials said an earthquake in the region could have been a possible factor.

The US Geological Survey later said the reported tremor was seismic energy caused by the collapse of glacial rock and ice, followed by a debris flow.

Shugar said satellite images appeared to show that significant snowmelt had occurred in the 24 hours before the disaster, with glaciers that had been snow-covered appearing mostly as bare ice. He said construction could also be a factor, while the role of climate change would require further investigation.

Glacier loss

The United Nations said in 2023 that Nepal’s snow-capped mountains had lost nearly one-third of their ice in just over 30 years because of global warming.

It also said glaciers in Nepal, between India and China, melted 65 per cent faster in the previous decade than in the decade before it.