Nepal disaster caused by river blockage, not earthquake, experts say
At least 160 people died in a devastating mud and water surge along the Nepal-Tibet border, caused by a rock-ice avalanche that blocked a river rather than the initially reported earthquake. Experts warn of a possible second flood and point to climate trends affecting the Himalayas.
A disaster that struck along the Nepal-Tibet border on Wednesday morning has killed at least 160 people, with hundreds still missing. Footage from the Chinese side shows a towering wall of mud and debris crashing over a multi-storey building and sweeping away vehicles.
Landslide, not earthquake
Nepal's Foreign Minister Shishir Khanal initially said an earthquake triggered a landslide that blocked a river, which later burst and sent water rushing downstream. However, the US Geological Survey has since clarified that the seismic signal, initially read as a magnitude 4.4 earthquake, actually originated from the landslide itself. The Kathmandu-based International Centre for Integrated Mountain Development (ICIMOD) concluded that a rock-ice avalanche in Nepal blocked the Lhende river, triggering the cascading flood.
Why warning systems failed
Hatim Sharif, a hydrologist at the University of Texas San Antonio, noted the absence of rainfall beforehand, which undermines most standard flood warning systems. He said that by the time the mud flow becomes visible, it is too late to escape — running or driving away will not work, since the fast-moving mixture behaves like liquid concrete. The only real chance of survival is climbing at least six metres uphill. A longer-term fix could involve river-level gauges that give residents 20 to 30 minutes of advance warning.
Risk of a second flood and climate factors
ICIMOD's Qianggong Zhang warned that an ongoing blockage upstream could trigger a second flood. Nepal is also vulnerable to glacial lake outburst floods, such as one that hit Rasuwa District in July 2025, though authorities have not confirmed a similar mechanism this time. Scientists intend to carry out attribution studies to assess any climate change link. Researcher Dorothy Heinrich of the University of Reading noted that the Himalayas are already experiencing well-documented trends — more heatwaves, glacial retreat and permafrost loss — that can increase the likelihood of landslides and outburst floods, though a definitive connection requires a formal attribution study.
