A massive piece of ice that fell thousands of metres from a glacier into a river below may have triggered the disaster in Nepal and Tibet.
Scientists are still piecing together information from satellite and ground-level data to figure out exactly what happened to cause the flood, which killed at least 353 people and left more than 1,300 missing, including foreigners and pilgrims.
"A large chunk of glacier fell from about 5,200 metres into a valley," said Simon Cox, principal scientist at New Zealand's GNS Science.
It "transformed into this raging mass of debris... where it picks up rocks and sediment and trees and anything in the way and fires it on down through the canyon," he told AFP.
The wall of water first hit a border post, with CCTV footage showing mud and debris engulfing the area as people fled. It then travelled downstream into Nepal, flooding villages and destroying bridges and buildings.
