Video shows scale of flash flood hitting Nepal-Tibet border
Massive landslides and flash floods on the Nepal-Tibet border have caused widespread damage and left hundreds dead or missing.
Search and rescue operations are continuing after Wednesday's disaster. Chinese state media has said there are significant casualties, while Nepalese officials describe "huge scale loss".
But rescuers are on edge because of the risk of further flooding. A lake of rising water has formed at a site along the border, prompting Chinese authorities to suspend rescue efforts in Tibet for fear it may burst its banks.
Military teams were brought in to help with rescue and evacuation following the flooding on Wednesday
Initial reports of an earthquake on the Nepal-Tibet border led many to believe that a tremor had caused a landslide, which in turn caused the devastating flood.
However, the US Geological Survey has clarified that the disaster was caused by a "glacial collapse", which is when a glacier or part of a glacier disintegrates.
The impact of the collapsed glacier hitting the bottom of a valley was so powerful that it registered a magnitude of 5.2, according to USGS data and scientists who have analysed the event.
Debris flow from the collapse "caused subsequent catastrophic impacts downstream" the USGS said.
Climate change is known to be driving faster glacier melt in the Hindu Kush Himalaya region. Scientists are trying to piece together the exact order of events as rescue efforts continue.
Geologist Daniel Shugar – one of the first experts to suggest Wednesday's flash flooding event could have been caused by glacial activity – says glacial thinning inducted by global warming can increase the risk of landslides.
But it is still too early to definitively link the event to climate change, Shugar, who is based at the University of Calgary in Canada, tells the BBC.
Simon Cook, a geoscientist at the University of Dundee, says however, that climate change "could have an impact". Cook added that his team believed they had identified where the collapse had occured. He told the BBC that the lower part of a glacier in Nepal near the Langtang Lirung peak – approximately 15km (9 miles) west of the site of the floods – had collapsed.
He estimated that the glacier collapsed in a north-westerly direction and then travelled westwards downstream.
He told the BBC "permafrost is partially holding some mountainsides together, this permafrost is warming and thawing and degrading so you are going to get more landslides".
