A powerful landslide involving ice and rock, rather than an earthquake, triggered the deadly flash floods that swept through parts of Nepal and Tibet, the United States Geological Survey (USGS) said, clarifying an earlier report of seismic activity.The USGS initially recorded what appeared to be a 4.4-magnitude earthquake at around 8:37 am, Nepal time on Wednesday along the Nepal-China border. It later revised its assessment, saying the event was “instead a glacial collapse and debris flow” that caused catastrophic impacts downstream.”No earthquake had occurred,” the agency said.Reuters, citing an initial analysis of Planet Labs satellite imagery, reported that a landslide of ice and rock sent a massive debris flow into the Lhende Khola River, triggering a flood laden with mud and debris. The river, which flows from Tibet into Nepal, is a tributary of the Bhote Koshi.The exceptionally powerful landslide generated seismic energy equivalent to an earthquake measuring about 5.2 magnitude, according to the assessment.Death toll rises as rescue efforts continueAt least 157 bodies have been recovered in Nepal, with authorities warning that the toll could rise as rescue teams search through mud and debris.The floods devastated parts of Rasuwa, Dhading and Nuwakot districts after the torrent surged through the Bhote Koshi River at around 9 a.m. local time. Homes, vehicles and trees were submerged or buried, while damaged hydropower infrastructure left many communities without electricity.Nepalese police and military personnel have been conducting rescue operations, while helicopters have been deployed to evacuate survivors and deliver assistance. Officials said some areas remain inaccessible to helicopters until floodwaters recede.Prime Minister Balendra Shah has pledged to deploy all available government resources to the relief and rescue effort.Hundreds of tourists reported missingThe disaster also disrupted travel in the region. Nepal’s tourism authorities said more than 400 tourists, including hundreds of foreign nationals, were initially unaccounted for after the floods.Those reported missing included Indian, Australian, British, Malaysian, Dutch, Portuguese, South African, South Korean and U.S. nationals. Indian nationals made up a significant share of those reported missing, including pilgrims believed to have been in the affected region.Residents from Nuwakot and Dhading gathered outside a Nepal Army training centre serving as a base for helicopter rescue operations, seeking information about relatives whose whereabouts remained unknown.Police recorded names of missing people outside the barracks, at times using mobile-phone flashlights as the surrounding area remained without power.Tibet also hit by deadly floodsThe disaster extended across the border into Tibet, where China’s state broadcaster reported three deaths and 265 people missing in Gyirong. Authorities said the reported 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 rocks, mud and water swept through the area, destroying buildings and vehicles.India, UN step up supportThe disaster also prompted flood alerts in neighbouring India. About 5,000 people were evacuated in Bihar after authorities warned of rising water levels.The United Nations said it was mobilising supplies and personnel to support affected communities. India said it was coordinating with Kathmandu on rescue and relief operations, while South Korea was preparing to send a rapid-response team.Rescue workers are continuing to search for survivors and recover bodies as heavy deposits of mud and debris complicate operations across the affected areas.Inputs from Reuters