Note: Single-source report; awaiting corroboration.
A massive mountainside collapse in the Himalayas triggered a deadly flood on Wednesday morning. Seismic instruments initially mistook the event for a magnitude 5.2 earthquake. The disaster was caused by bedrock failure beneath a glacier, which sent about 1,200 meters of ice and rock toward the valley floor, unleashing water, sediment, and boulders into the river below along one of Nepal's main trade routes with China.
The collapse caused a destructive cascade downstream, with water levels rising as much as nine meters within half an hour at monitoring sites. The floods have resulted in more than 500 deaths and left over 1,500 people missing across Nepal and Tibet, including many foreign nationals.
Dr. Dipesh Chapagain, a climate researcher originally from eastern Nepal and now at the United Nations University in Bonn, Germany, said the disaster illustrates the growing hazards posed by the changing Himalayan landscape. He noted that such risks were not major concerns for previous generations, but are now becoming more frequent and intense.
Experts are reconstructing the exact sequence of events, but satellite imagery suggests the catastrophic glacier-bedrock failure was the trigger. Unlike typical glacial lake outburst floods, recent research from the Global Mountain Safeguard Research programme (GLOMOS) shows these events have increased about fivefold since 1950.