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Scientists found 'pre-event indications' of Nepal glacier collapse, report says
A rapid assessment by an international group of scientists found 'pre-event indications' of the glacier collapse that triggered deadly flash floods along the Nepal-China border, with satellite imagery showing changes to the glacier's surface before it gave way. The HiRISK report's findings have raised questions about whether better early warning systems could have reduced the death toll, which has surpassed 1,100. Experts quoted in the report and in interviews with the ABC say the failure to act on known risks contributed to the scale of the disaster.
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Scientists found 'pre-event indications' of Nepal glacier collapse, report says
KATHMANDU — Days before a glacier collapse triggered devastating flash floods along the Nepal-China border, satellite imagery was already showing warnings of the coming disaster, according to a new report by an international group of scientists. The findings have intensified scrutiny of whether stronger early warning systems and disaster preparedness could have saved lives.
The initial findings, prepared by HiRISK on August 28, say there were "pre-event indications" of the avalanche, including a change in the surface of the collapsed glacier. The report was compiled by experts from the Asian Mountain Academic Alliance, the Stimson Center, and China's Institute of Mountain Hazards and Environment.
The glacier collapse triggered a massive landslide and flash floods that tore through the valley, killing more than 1,100 people, according to Nepal Police figures reported by The Times of India. The number of missing has risen above 3,900, with hundreds of Nepali, Chinese, and Indian construction workers among them, the ABC reported.
Pre-event indications
When the scientists analysed satellite imagery of the affected area days before the collapse, they found signs that something was amiss. According to the report, satellite observations suggest the water in the glacier accelerated before the collapse, a sign that something was shifting inside and that the surrounding rock was weakening.
The satellite imagery from August 24 also showed meltwater in the area had turned visibly brown, while the scientists identified a crack propagating into the surrounding bedrock slope in the days before the collapse. "In hindsight, there were some pre-event indications," the scientists said, as cited by The Times of India.
Jakob Steiner, a co-author of the report and a geologist who has been advising the Nepali government on disaster risk in the Himalayas, told the ABC that early warning systems for construction workers were "very weak." Steiner said the previous disasters in the region should have provided enough warning, and that authorities need to be questioned why "very little" had been done to prepare.
"We can't say, on my God, nobody knew," he said.
Early warning gaps
According to the HiRISK report, no early warning system for glacier-related hazards had been set up in the affected area. The report noted that conventional systems would have provided minimal warning at the Nepal-China border checkpoint at Rasuwagadhi, known in China as Gyirong Port, and would likely have been insufficient for successful evacuation. However, further downstream, with warning times of 10 minutes or more, comprehensive and well-capacitated systems could have saved a "significant number of lives," the report stated.
Steiner said AI-assisted satellite monitoring could help scientists identify risks across vast and difficult mountain terrain. "There are thousands and thousands of glaciers in High Mountain Asia, so we have to find scalable solutions," he told the ABC.
The report emerges as the region deals with recurring glacier-related disasters. In July of last year, a glacial lake outburst flood hit the same Nepal-China border checkpoint, destroying roads and a bridge and killing at least nine people. A rock-ice avalanche affected the same area in July 2024, and there was an earthquake-triggered ice avalanche in April 2015.
"The magnitude of all of [these events] coming together and then happening after each other in the same location is a concerning thing, and this is what we call multi-hazard events," Steiner said.
Rescue and recovery
The disaster has left hundreds of construction workers trapped at several hydropower projects along the Trishuli River. On Monday, the Nepali government said at least 933 workers were believed to be trapped at about half a dozen sites. Rescuers have so far evacuated about 300 workers from a collapsed Upper Trishuli tunnel, the ABC reported.
Arnold Dix, an Australian geologist and engineer assisting with rescue work, estimated the floodwaters would have been travelling at more than 160 kilometres per hour, leaving only about 10 minutes for a response. "There were people at the construction camp, 10 minutes wouldn't be long enough to run from camp to the tunnels," he said.
Twelve hydropower facilities and a solar plant — about 10 per cent of Nepal's total operational capacity — have been shut down as a result of the floods, with seven damaged or destroyed. Three projects, Upper Trishuli-1, Upper Trishuli-3A, and Upper Trishuli-3B, have reportedly been severely damaged.
Looking ahead
The disaster has raised concerns about the broader vulnerability of the Himalayan region. The Times of India reported that separate reports by the International Centre for Integrated Mountain Development (ICIMOD) found that glaciers in the Hindu Kush Himalaya region lost around 12 per cent of their total area and 9 per cent of their estimated ice reserves between 1990 and 2020. ICIMOD's 2026 Glacier Outlook found that only seven of 38 monitored glaciers met the global benchmark monitoring standards set by the World Glacier Monitoring Service.
Steiner said both Nepali and Chinese governments need to do more to protect construction workers in the region, calling for investment in monitoring and early warning systems. "To put it … cynically, there was a lot of hot air, but very little was [done]," he said.
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Framing: Emphasizes that warning signs were visible days before the glacier collapse, based on a report — serious and critical
Facts Included:
A rapid hazard assessment of the Nepal-Tibet disaster by a group of international scientists says there were 'pre-event indications' of the avalanche, including satellite imagery showing a change in the surface of the collapsed glacier
The initial findings prepared by HiRISK on August 28 have raised questions about whether better disaster preparedness may have prevented hundreds of construction workers from becoming trapped at several hydropower projects after the deadly floods on
Jakob Steiner, a co-author of the report and a geologist who has been advising the Nepali government on disaster risk in the Himalayas, also told the ABC that early warning systems for construction workers were 'very basic'
In the past decade, China and Nepal have launched a number of high-altitude infrastructure projects, including highways, dams, tunnels and hydropower plants along the border
Several of those projects were damaged by the massive flash flood that tore through the valley last Wednesday
The number of people missing has risen to more than 3,900 with at least 1,000 people known to have died
Among the missing are believed to be hundreds of Nepali, Chinese and Indian construction workers building roads, hydro-electric dams and their tunnels along the Trishuli River
On Monday, the Nepali government said at least 933 workers were believed to be trapped at about half a dozen hydropower projects
They have so far evacuated about 300 workers from a collapsed Upper Trishuli tunnel
In May, experts and officials from Nepal and China met in Kathmandu to discuss the risk of disasters in the border area, according to a Reuters report
They discussed floods and glacier-related hazards, as well as monitoring and response measures, according to a meeting agenda prepared by the Nepali government
The participants called for joint risk-reduction steps, including monitoring glacial lakes and mapping the hazards
Jakob Steiner says satellite monitoring could help scientists identify risks across vast and difficult mountain terrain
According to the HiRISK report, no early warning system for glacier-related hazards had been set up in the affected area so far
Given the rapid speed of the initial avalanche, warning time from conventional systems would have been minimal and likely insufficient for successful evacuation at the Nepal-China border check point at Rasuwagadhi [Gyirong Port], it said
Further downstream, with warning times of 10 minutes or more, comprehensive and well-capacitated systems could have saved a significant number of lives
The HiRISK report was penned by experts from the Asian Mountain Academic Alliance, the Stimson Center, and China's Institute of Mountain Hazards and Environment
When the experts analysed satellite imagery of the affected area days before the glacier collapse, they found 'there were some pre-event indications' of the collapse
According to the report, one sign was a change in the glacier's surface
Satellite observations suggest the water in the glacier accelerated before the collapse, a sign that something was shifting inside and that the surrounding rock was weakening
The satellite imagery from August 24 also showed that meltwater in the area had turned visibly brown, while the scientists also identified a crack propagating into the surrounding bedrock slope in the days before the collapse
Mr Steiner said AI-assisted satellite monitoring could help scientists identify risks across vast and difficult mountain terrain
This is where I think we need to invest more,' he said
There are thousands and thousands of glaciers in High Mountain Asia, so we have to find scalable solutions
In July last year, a glacial lake outburst flood sent floodwaters through the Nepal-China border checkpoint — known in China as the Gyirong port— destroying roads and a bridge linking the two countries
It left at least nine people dead
Last Wednesday, the Gyirong port was again hit by floodwatersbut was this time completely destroyed
There were also similar incidents in previous years
A rock-ice avalanche affected the same area in July 2024, and there was an earthquake-triggered ice avalanche in April 2015
The magnitude of all of [these events] coming together and then happening after each other in the same location is a concerning thing, and this is what we call multi-hazard events,' said Mr Steiner, who has surveyed the valley where the avalanche occurred
Mr Steiner said the previous disasters should have provided enough warning, and that authorities need to be questioned why 'very little' had been done to prepare
We can't say, on my God, nobody knew,' he said
Zhang Maoming, Chinese Ambassador to Nepal, told NTV news last week that both Nepal and China 'can learn a lot from responding to this disaster'
It is imperative for China and Nepal to further strengthen cooperation in disaster prevention, mitigation and emergency management, and continuously enhance our capacity to respond to natural disasters,' he said
China was involved in building at least four hydro-electric dam and tunnels projects about 35 kilometres down the the river from Gyirong port
Three of them, Upper Trishuli-1, Upper Trishuli-3A and Upper Trishuli-3B, have reportedly been severely damaged by the flood,with rescue works ongoing
In total, 12 hydropower facilities and a solar plant, about 10 per cent of Nepal's total operational capacity, have been shut down
Seven of them have been damaged or destroyed, according to the reports
Mr Steiner said every construction project underwent detailed environmental and risk assessments, but what was not clear was whether they had been followed through
The construction workers were 'more exposed' because they lived in barracks close to the hydropower infrastructure, he said
They are like … Lord of the Rings kind of dwarf caves,' he said
Mr Steiner said considering hundreds of people worked in each 'cave' and the risk of natural disasters, the early warning systems were still 'very basic'
He said after the 2025 rock-ice avalanche, he met with local authorities and advocated for ongoing training for staff and for disaster management authorities to monitor early warning signs of potential disasters in the valley
But he said there had been 'no investment' in those measures
To put it … cynically, there was a lot of hot air, but very little was [done],' he said
He said both Nepali and Chinese governments needed to do more to protect construction workers in the region
Arnold Dix, an Australian geologist and an engineer, is helping with the Nepali rescue work at the collapsed tunnel at hydropower station
He estimated the flood waters would have been travelling at more than160 kilometres an hour, which would have left only about 10 minutes for a response
There were people at the construction camp, 10 minutes wouldn't be long enough to run from camp to the tunnels [which were more resilient to the flood],' he said
Professor Dix said that in retrospect, other measures could have also been put in place
We might make access points to underground caverns
We might be able to build something man-made to try and slow down a huge amount of energy like that
But at the moment, I'm just scratching my head
Professor Dix said the engineering design of hydropower station Trishuli-3A looked reasonable and had already factored in potential geological conditions
Tunnel expert Chris Cooper, who is also helping with rescue work in Nepal, said people also needed to plan for risks outside the project boundary
At the moment when you do a project, you know what your annual flood levels are and you design the project around the maximum flood levels,' he told the ABC's The World program
He said what happened along Trishuli River was 'catastrophic', and he doubted that any project would have factored that into its project design
Moving forward, Mr Cooper said there needed to be a better monitoring system and cross-border data sharing system between relevant countries
An international team of scientists found 'pre-event indications' of the avalanche in satellite imagery showing changes to the glacier's surface before it collapsed.
The initial findings, prepared by HiRISK on August 28, raise questions about whether stronger disaster preparedness and early warning systems could have prevented the loss of 1,000 lives.
Jakob Steiner, co-author of the report and a geologist who has advised the Nepali government on disaster risk, told the ABC that early warning systems for construction workers were 'very weak'.
In May, experts and officials from Nepal and China met in Kathmandu to discuss disaster risk in the border area, according to a Reuters report.
The participants called for joint risk-reduction steps, including monitoring glacial lakes and mapping hazards.
The HiRISK report was penned by experts from the Asian Mountain Academic Alliance, the Stimson Center, and China's Institute of Mountain Hazardsand Environment.
Satellite imagery from August 24 showed meltwater in the area had turned visibly brown, and identified a crack propagating into the surrounding bedrock slope in the days before the avalanche.
The report said warning time from conventional systems would have been minimal and likely insufficient for successful evacuation at the Nepal-China border check point at Rasuwagadhi [Gyirong Port].
Thousands of people are still missing, including 933 construction workers from Nepal, China,and India, with hundreds reportedly trapped at hydropower sites.
The glacier collapse triggered a devastating landslide and flash floods along the Nepal-China border, killing over 1,100
The HiRISK report, published last week, cited by CNN, examined the physical changes preceding the glacier collapse
Scientists said there were "pre-event indications", including meltwater that had turned visibly brown and signs of a crack propagating into the surrounding bedrock slope
The report said early warning systems had recently been established in the region to monitor several glacial lakes in China, but no operational system was in place specifically for glacier-related hazards in the area where the collapse occurred
The scientists said comprehensive early warning systems capable of providing 10 minutes or more of advance notice could have saved a "significant number of lives"
1,127 people have died in the floods, according to Nepal Police
Nine bodies have also been recovered in India
So far, only 95 of the total recovered bodies have been identified and handed over to their families
Chinese and Nepali authorities had met as recently as May to discuss strengthening cooperation on monitoring natural hazards in the region
Austin Lord, a senior fellow in the Energy, Water and Sustainability programme at the Stimson Center, wrote in a recent commentary
The HiRISK report is separate from two major reports released by the International Centre for Integrated Mountain Development (ICIMOD) in March 2026
ICIMOD reports found that HKH glaciers lost around 12 per cent of their total area and 9 per cent of their estimated ice reserves between 1990 und 2020
ICIMOD's 2026 Glacier Outlook found that only seven of 38 monitored glaciers met the global benchmark monitoring standards set by the World Glacier Monitoring Service
AI-extracted; can misattribute a claim — see Methodology.
Each row is one claim, attributed to the outlet whose wording states it most clearly. Confidence rates how directly the source text states the claim — explicit and unhedged rates high; hedged, pieced-together, or internally inconsistent statements rate lower. It does not measure whether the claim is true. Status is Contested when two claims on this page negate each other; otherwise it counts the distinct outlets we found asserting that specific claim — so a single-source claim can still show high confidence, and a multi-source claim can show medium. Every one of those outlets is named beside the status, so you can check the count against the list. For claims extracted before we began storing that list, the row says so: it names the outlet the claim is quoted from and states that we have not recorded which outlets backed it. Outlets wrote at different times, so a figure that evolves — a casualty count, for example — can legitimately differ between rows; check the "as of" time next to each claim's source.
Claim
Confidence
Status
ClaimA rapid hazard assessment of the Nepal-Tibet disaster by HiRISK found 'pre-event indications' of the avalanche, including satellite imagery showing a change in the surface of the collapsed glacier.
ClaimThe initial findings prepared by HiRISK on August 28 have raised questions about whether better disaster preparedness may have prevented hundreds of construction workers from becoming trapped at several hydropower projects after the deadly floods.
ClaimJakob Steiner, a co-author of the report and a geologist who has been advising the Nepali government on disaster risk in the Himalayas, told the ABC that early warning systems for construction workers were 'very weak'.
ClaimIn the past decade, China and Nepal have launched a number of high-altitude infrastructure projects, including highways, dams, tunnels and hydropower plants along the border.
ClaimAmong the missing are believed to be hundreds of Nepali, Chinese and Indian construction workers building roads, hydro-electric dams and their tunnels along the Trishuli River.
ClaimIn May, experts and officials from Nepal and China met in Kathmandu to discuss the risk of disasters in the border area, according to a Reuters report.
ClaimThey discussed floods and glacier-related hazards, as well as monitoring and response measures, according to a meeting agenda prepared by the Nepali side.
ClaimGiven the rapid speed of the initial avalanche, warning time from conventional systems would have been minimal and likely insufficient for successful evacuation at the Nepal-China border check point at Rasuwagadhi [Gyirong Port], it said.
ClaimFurther downstream, with warning times of 10 minutes or more, comprehensive and well-capacitated systems could have saved a significant number of lives.
ClaimThe HiRISK report was penned by experts from the Asian Mountain Academic Alliance, the Stimson Center, and China's Institute of Mountain Hazardsand Environment.
ClaimWhen the experts analysed satellite imagery of the affected area days before the glacier collapse, they found 'there were some pre-event indications' of the collapse.
ClaimSatellite observations suggest the water in the glacier accelerated before the collapse, a sign that something was shifting inside and that the surrounding rock was weakening.
ClaimThe satellite imagery from August 24 also showed that meltwater in the area had turned visibly brown, while the scientists also identified a crack propagating into the surrounding bedrock slope in the days before the collapse.
ClaimIn July last year, a glacial lake outburst flood sent floodwaters through the Nepal-China border checkpoint — known in China as the Gyirong port— destroying roads and a bridge linking the two countries.
ClaimThe magnitude of all of [these events] coming together and then happening after each other in the same location is a concerning thing, and this is what we call multi-hazard events,' said Mr Steiner, who has surveyed the valley where the avalanche occurred.
ClaimMr Steiner said the previous disasters should have provided enough warning, and that authorities need to be questioned why 'very little' had been done to prepare.
ClaimIt is imperative for China and Nepal to further strengthen cooperationin disaster prevention, mitigation and emergency management, and continuously enhance our capacity to respond to natural disasters,' he said.
ClaimThree of them, Upper Trishuli-1, Upper Trishuli-3A and Upper Trishuli-3B, have reportedly been severely damaged by the flood,with rescue works ongoing.
ClaimMr Steiner said every construction project underwent detailed environmentaland risk assessments, but what was not clear was whether they had been followed through.
ClaimMr Steiner said considering hundreds of people worked in each 'cave' and the risk of natural disasters, the early warning systems were still 'very basic'.
ClaimHe said after the 2025 rock-ice avalanche, he met with local authoritiesand advocated for ongoing training for staffand for disaster management authorities to monitor early warning signs of potential disastersin the valley.
ClaimHe estimated the flood waters would have been travelling at more than160 kilometres an hour, which would have left only about10 minutes for a response.
ClaimThere were people at the construction camp,10 minutes wouldn't be long enough to run from camp to the tunnels [which were more resilient to the flood],' he said.
ClaimProfessor Dix said the engineering design of hydropower station Trishuli-3A looked reasonableand had already factored in potential geological conditions.
ClaimTunnel expert Chris Cooper, who is also helping with rescue work in Nepal, said people also needed to plan for risks outside the project boundary.
ClaimAt the moment when you do a project, you know what your annual flood levels are and you designthe project aroundthe maximum flood levels,' he told the ABC's The World program.
ClaimThe report said early warning systems had recently been establishedin the region to monitor several glacial lakesin China, but no operational system was in place specifically for glacier-related hazards in the area where the collapse occurred.
ClaimThe scientists said comprehensive early warning systems capable of providing10 minutes or more of advance notice could have saved a "significant number of lives".
ClaimThe HiRISK report is separate from two major reports released by the International Centre for Integrated Mountain Development(ICIMOD)in March2026.
ClaimICIMOD reports found that HKH glaciers lost around12 per cent of their total areaand9 per cent of their estimated ice reserves between1990und2020.
ClaimICIMOD's2026 Glacier Outlook found that only seven of38 monitored glaciers metthe global benchmark monitoring standards set by the World Glacier Monitoring Service
ClaimAn international team of scientists found 'pre-event indications' of the avalanchein satellite imagery showing changes to the glacier's surface before it collapsed.
ClaimThe initial findings, prepared by HiRISKon August28, raise questions about whether stronger disaster preparednessand early warning systems could have prevented the loss of1,000 lives.
ClaimSatellite imagery from August24 showed meltwaterin the area had turned visibly brown,and identified a crack propagating into the surrounding bedrock slopein the days before the avalanche.
ClaimThousands of people are still missing, including933 construction workers from Nepal, China,and India, with hundreds reportedly trapped at hydropower sites.