The tremors associated with the deadly flash floods in Nepal on Wednesday morning were caused by a powerful landslide involving ice and rock, rather than an earthquake, the United States Geological Survey (USGS) clarified.
The agency said the seismic activity initially reported as an earthquake “was instead a glacial collapse and debris flow” that caused catastrophic impacts downstream.
The USGS had initially reported seismic activity along the Nepal-China border, north of Kathmandu. It later clarified that the event was not an earthquake.
“No earthquake had occurred,” the agency said.
Landslide triggered debris-laden flood
An initial study of satellite imagery from Planet Labs indicated that a landslide involving ice and rock triggered a debris-laden flood in the Lhende River.
The landslide occurred about 20 km northeast of the Nepal-China Rasuwagadhi border crossing.
The Lhende Khola River is a tributary of the Bhote Koshi River, which flows from China into Nepal. The powerful landslide sent debris and water downstream, triggering the flash floods.
The event was later registered as seismic activity equivalent to an earthquake measuring 5.2 in magnitude.
157 bodies recovered in Nepal
Relief and rescue operations are underway in Rasuwa and other affected areas following the floods.
Nepal Police have recovered 157 bodies, while authorities are working to move families living in flood-risk areas to safer locations.
At least 403 tourists, including 341 foreigners, were reported unaccounted for several hours after the disaster, according to the tourism ministry.
The missing foreigners included 142 Indians, along with nationals from Australia, Britain, Malaysia, the Netherlands, Portugal, South Africa, South Korea and the United States, according to the tourism board.
Rescue teams are searching for survivors and bodies buried under mud and debris. Prime Minister Balendra Shah has pledged government resources for relief and rescue operations.
Floods hit several districts
The flood surged through the Bhote Koshi River at around 9 am local time after crossing over from the Tibet side.
Rasuwa and Dhading, which border Tibet, along with Nuwakot, were among the affected districts.
In Tibet, China’s state broadcaster reported that three people were killed and 265 were missing in Gyirong. It said the deaths were still being verified and rescue operations were continuing.
Security footage from the Nepal-Tibet border showed people fleeing moments before a torrent of rock, mud and water swept through the area, destroying buildings and vehicles.
Families search for missing relatives
Residents from affected areas of Nuwakot and Dhading gathered outside a Nepali Army training centre that was being used as a base for helicopter rescue operations.
People sought information about relatives who remained missing after the floods. Police were recording the names of missing people outside the barracks as the area remained without electricity because of damage to hydropower infrastructure.
Across the affected areas, houses, trees and vehicles were submerged or buried beneath mud and debris.
Helicopters continued rescue operations, bringing survivors out of the flood-hit areas.