A massive glacier collapse in the Himalayas sent a rock-and-ice avalanche into the valley on the Nepal–China border — and the debris flow was powerful enough to register on seismometers as the equivalent of a magnitude 5.2 earthquake.
That is why early reports, including statements from Nepali officials, described this as an earthquake-triggered event. USGS has since determined the order was reversed: the glacial collapse and the debris flow that followed produced the seismic signal, and no quake occurred. In this video I go through the USGS determination, what the long-period seismic waves actually showed, and I walk the location on Google Earth — including the roughly 9,000-foot drop from where the glacier failed down to the valley floor.
⚠️ This video covers an active disaster with confirmed loss of life and contains footage some viewers will find distressing. Information is preliminary as of August 26, 2026. Our thoughts are with everyone affected in Nepal and Tibet; rescue and recovery operations are ongoing.
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WHAT WE KNOW
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- A substantial portion of a glacier snout collapsed high in the mountains, entraining a large volume of rock and sediment on the way down.
- The resulting rock-ice avalanche and debris flow entered the Lhende Khola, a tributary of the Bhote Koshi, near the Nepal–China border crossing in Rasuwa district. Local time was approximately 08:37.
- The flow generated a seismic signal equivalent to a magnitude 5.2 event. It was initially reported as an M4.4 earthquake.
- USGS analysis of long-period seismic waves, combined with satellite imagery, indicates this was not a tectonic earthquake. The landslide produced the signal.
- This is not simple glacial melt. A section of the mountainside gave way and became a wall of water, ice and mud that destroyed bridges, buildings and infrastructure downstream.
- Hundreds of people were reported missing. This is not remote, uninhabited terrain — it is a populated corridor and a route used by pilgrims traveling toward Lake Mansarovar.
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WHAT WE DON'T KNOW YET
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- Why the glacier failed when it did. Warming, meltwater at the bed, and slope instability are all on the table, and separating them takes weeks of work.
- Where all the water came from. The glacier itself, a stored meltwater pocket, a temporary landslide dam that then breached, or some combination.
- Whether there was one failure or several. Reporting is still chaotic and the imagery may show more than one path down.
- The full extent of the damage. Access is limited to helicopter in much of this area.
Anyone giving you a confident single cause tonight is ahead of the data. I would rather come back with the real answer.
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WHY THE DISTINCTION MATTERS
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If an earthquake caused this, it is a seismic hazard story and the warning problem is seismic monitoring. If the glacier failed on its own and the shaking was a byproduct, the monitoring problem moves to ice, meltwater and slope stability across thousands of high valleys that currently have almost no instrumentation. These are cascading hazards: one failure high in the mountains becomes a flood in towns far downstream, often within minutes. Getting the sequence right determines where you put the sensors.
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CHAPTERS
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0:00 What happened
0:00 The footage
0:00 The USGS determination
0:00 Why it was reported as an earthquake
0:00 Google Earth: the 9,000-foot drop
0:00 The Langtang and border region
0:00 What we still don't know
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FOOTAGE CREDITS
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Ground-level footage — Surajit on X
Nepal / China border footage — XAlertNow on X
Flood footage — Ravi Pandey on X
Imagery — Guillaume Woznica on X
Glacier collapse footage — Massimo on X
Flood footage — ElBuni on X
Mudslide footage — Clash Report on X
Satellite imagery — Planet Labs
Seismic data and event determination — USGS Earthquake Hazards Program
Official statements — Nepal National Disaster Risk Reduction and Management Authority (NDRRMA)
Regional hazard context — International Centre for Integrated Mountain Development (ICIMOD), Kathmandu
All footage remains the property of its respective owners and is used here for news reporting and scientific commentary. If you are a rights holder and would like a credit corrected or your material removed, contact
rays@rayliens.com and I will act on it immediately.
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#Nepal #Himalaya #Glacier #GlacierCollapse #Landslide #Earthquake #USGS #Rasuwa #BhoteKoshi #Langtang #FlashFlood #Cryosphere #ClimateScience #Geology 
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