Satellite images showed warning signs before Nepal glacier collapse that killed over 1,000

Satellite images captured warning signs in the days before the Nepal glacier collapse that killed more than 1,000 people, scientists say.

HiRISK, a scientific group that studies disasters in high-mountain Asia, released preliminary findings from a rapid disaster assessment of the Nepal-Tibet catastrophe on Aug. 28, according to Australia's ABC News.

The report, as cited by ABC News, said the avalanche had "precursory signals." Satellite imagery taken days before the disaster showed surface changes on the collapsed glacier, meltwater that had turned brown, and cracks spreading across surrounding rock slopes.

The disaster began when a roughly 600-meter-wide mass of glacier broke away from a cliff face. The ice and rock fell more than 1,200 meters vertically before crashing into the Rondi Khola valley. The US Geological Survey initially logged the event on Wednesday, as a magnitude-4.4 earthquake, then corrected the record, saying it was the impact of hundreds of millions of tons of ice and rock striking the valley floor.

HiRISK said that given the initial speed of the avalanche, "the warning time that could have been secured through conventional systems would have been short," adding that evacuation from border checkpoints between Nepal and China "would likely have been very difficult."

However, the group said, "had an early warning been issued, a significant number of lives could have been saved in downstream areas."

Jakob Steiner, a geoscientist at the University of Graz in Austria and co-author of the report, told ABC News that the early warning system for construction workers had been "very weak." Steiner has advised the Nepalese government on Himalayan disaster risks.

Steiner said workers had been living in accommodations built close to the work site, and that authorities had failed to invest in monitoring capacity and worker training despite a similar rock-and-glacier avalanche in 2025.

The report was produced by experts from the Asian Mountain Academic Alliance, the US-based Stimson Center, and China's Institute of Mountain Hazards and Environment.

According to Reuters, Chinese and Nepalese experts met in Kathmandu on May 27 to discuss disaster risks, monitoring and response measures in the border region. Nepal told Reuters it had not received as much information as it wanted from China regarding glacier hazards and water levels following those talks.

Meanwhile, China and Nepal have been developing high-altitude infrastructure — including highways, dams, tunnels and hydropower plants — in their border regions over the past decade. Hundreds of workers at a hydropower construction site remain trapped following the disaster.