What Caused Nepal's Devastating Flood?
The catastrophic flood that swept through northern Nepal on Wednesday morning, destroying towns and infrastructure and leaving scores dead or missing, is now believed to have been triggered by a massive chunk of glacier that broke away and plunged into a valley. According to preliminary geological analysis cited by The New York Times and reported by TASS, a snow-rock avalanche is the likely culprit.
Daniel Shugar, a geologist at the University of Calgary in Canada, who studied satellite imagery of the affected area, explained that a glacier in the region "basically broke clean off, allowing it to fall just over a vertical kilometer to the valley bottom." He described the aftermath as looking "like a bomb exploded — it's just deposits from the broken-up glacier."
Shugar estimated that the chunk of ice was about 2,000 feet wide, fell from an altitude of around 17,000 feet, dropping almost 4,000 feet. A team of international scientists, of which Shugar is a part, believes the massive ice block sheared off and fell into the river valley below, generating a wave of ice and water that carved a devastating path downstream.
The event occurred at a time when the US Geological Survey (USGS) recorded shaking at 8:37 am local time along the Nepal-China border, north of Kathmandu. Initially reported as a 4.4 magnitude earthquake, the USGS later clarified that the shaking was not caused by an earthquake but rather by the landslide itself, which registered as the equivalent of a magnitude 5.2 earthquake. In other words, the landslide caused the shaking, not the other way around.
Context: Climate Change and Glacier Instability
The flood struck the Himalayan region of Nepal, an area that is rapidly warming. As temperatures rise, glaciers are melting and destabilizing, and ice loss rates across the Hindu Kush Himalaya have doubled since 2000. Nearly 2 million people live downstream of these glaciers, facing what scientists describe as enormous risks.
Shugar, who is also affiliated with the University of California in other reports, noted that it is still too early to rule out other possible factors. But satellite imagery suggests that no major lakes are upstream of the flood path, indicating that a glacial lake outburst — a common flood risk in high mountain regions — can be excluded.
Recent weather conditions likely did not play a major role, as widespread intense rainfall has not been observed near the area over the past week. However, summer monsoon-fueled storms did bring some rain to the region, and seasonal rains and snowmelt would have made rivers run fuller, potentially amplifying the flood's impact.
Casualties and Rescue Efforts
The flood hit northern Nepal on Wednesday morning, unleashing torrents of water that swallowed towns, roads, and bridges. According to TASS, search and rescue teams have found the bodies of 95 people, and hundreds more were injured. Many houses and infrastructure were destroyed.
Earlier reports indicated that at least 384 travelers, including 291 foreign nationals, are missing in the flood zone. The rescue operation is ongoing, with teams combing through debris in the affected areas.
The exact causes of the flooding will take weeks to establish, scientists said, but the evidence so far points to a glacier collapse as the trigger, a phenomenon that is becoming increasingly common as the climate warms.