Dr Y Nithiyanandam

What Likely Happened on 26 August: A Terrain-Based Assessment. The disaster originated on the Nepal side, on the north face of Langtang Lirung inside Langtang National Park. Satellite imagery suggests this was not simply a glacier calving event but a large bedrock slope failure that carried part of the overlying glacier with it. The collapse, at roughly 5,100–5,200 m elevation, generated the seismic signal initially mistaken for an earthquake. The resulting ice-rock avalanche entered the Lhende Khola valley, close to the Nepal–Tibet boundary. This 3D terrain walkthrough with voice-over, using January 2026 imagery, shows the likely impact pathway: Slope failure → ice-rock debris enters the valley → possible temporary river blockage → water accumulates → blockage fails → sudden flood surge downstream. Note: The yellow line in the 3D walkthrough is the boundary line between Nepal and the Tibet Autonomous Region, China. The surge then travelled through the narrow valley, striking the Gyirong border checkpoint on the Chinese side, damaging major structures, before continuing downstream and affecting hydropower infrastructure and settlements on the Nepal side. Takshashila Institution Image credits: Google Earth. #NepalFloods #Nepal #Rasuwa #BhoteKoshi #Bhotekoshi #FlashFlood