The devastating flash flood that swept through parts of Nepal and Tibet was caused by tremors triggered by a glacier collapse and debris flow, rather than an earthquake, according to the US Geological Survey (USGS).
Nearly 160 people were killed and more than 750 remain missing, including 133 Indian nationals, after the massive flood destroyed towns and villages and washed away critical bridges.
According to the US agency, the seismic activity initially reported as a magnitude 4.4 earthquake was instead generated by a landslide involving ice and rock. “No earthquake had occurred,” the USGS said.
An initial analysis of Planet Labs satellite imagery had also indicated that a landslide of ice and rock triggered a debris-laden flood in the Lhende River, a tributary of the Bhote Koshi, about 20 km northeast of the Nepal-China Rasuwagadhi border crossing.
The flood entered the Trishuli River through the Bhote Koshi at Timure, a border town in Nepal’s Rasuwa district, following the rockslide and the sudden swelling of the Lhende River.
The torrent then spread downstream into several districts, including Nuwakot, Chitwan, Gorkha, Tanahun and Nawalparasi East, covering areas between about 70 km and nearly 200 km from Kathmandu, according to media reports.
With no rainfall reported in the area at the time, residents had little or no warning before the flash flood struck.
The disaster also caused extensive damage to critical infrastructure. Nine hydropower projects and nine branches of commercial banks were destroyed, while 19 motorable bridges and around 40 km of highway were swept away, according to a preliminary assessment cited by The Kathmandu Post.
The Indian Embassy in Kathmandu has issued emergency helpline numbers for assistance and information concerning Indian nationals affected by the floods. People can contact +977 985 131 6807 or +977 970 910 7500.
Officials said at least 133 Indians and 37 non-resident Indians (NRIs) are among the nearly 500 people reported missing. At least 50 of the Indian nationals were pilgrims travelling as part of the Kailash Mansarovar Yatra.
The Isha Foundation, a Coimbatore-based non-profit organisation, said 77 of its members who were at an immigration centre were missing.
Besides Indian nationals and NRIs, the missing tourists are believed to be from more than two dozen countries, including the United States, Malaysia, the United Kingdom, South Africa, Australia and the Netherlands.
