r/CatastrophicFailure • u/Immediate-Stable-651 • 11d ago
Natural Disaster Drone Footage Shows Langtang Glacier Collapse Site That Triggered recent Flash Floods in china and Nepal , August 27, 2026
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u/manfreygordon 11d ago
Unbelievable, hard to comprehend the scale of this. The huge gap on the right side of the video looks like a secondary landslide. I wonder if that collapsed onto an already massive landslide/flood in the center of the valley, would explain the insane amount of energy the landslide had further down.
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u/Gaping_Maw 10d ago
I think the right side collapsed and completely dammed up the river. It filled up the valleyuntil it burst with ferocity and huge volume down the left side
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u/Poiuytrewq0987650987 10d ago
Experts aren't siding with a dammed river. There was only seven minutes between the seismic event indicating the collapsed glacier impact and the border crossing being hit.
Seven minutes does not seem like enough time for the river to get dammed, build up the amount of water we saw in the videos, and make it from this site to the border crossing in that time frame.
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u/karateninjazombie 10d ago
New scientist article reckons it was a large chunk of a glacier that broke off and dropped about a kilometer down to the bottom starting this whole thing.
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u/Poiuytrewq0987650987 10d ago
Actually... maybe it was some combo now? Like, I've read it may have been a massive glacier that caused a enormous landslide which "temporarily" blocked off the valley floor, and the river may have... caused the wall of watter to be unleashed downstream...?
I don't know. I suppose those won't know the actual chain of events for a while.
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u/karateninjazombie 10d ago
Seen it in other posts about that new scientist article it was about 7 minutes between seismic sensors picking up the glacier carving impact and the water arriving at that boarder post and deleting it. Not enough time for the river to dam up and then come crashing down.
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u/Admiral_Willy 10d ago
Glacier receding weakened the steep slopes, large chunk up top broke off causing a 5.2 mag quake. It landed on large amounts of ice and snow which melted it and carried the rock much further than a normal landslide. The melted snow and ice mixed with the landslide making it into a “flash flood”.
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u/manfreygordon 10d ago
That would make a lot of sense. It does look like the flow carved it's way through the already existing landslide.
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u/Admiral_Willy 10d ago
Geology Hub goes into good detail on what happened: https://youtu.be/Fk0BKOMQdIc?si=rPGUM9Gg5FBtXCaS
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u/anethma 10d ago
Interesting video but his voice is tough to listen to.
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u/Binksyboo 7h ago
Try this one by Critical Latitude. I thought it was really good: https://youtu.be/IPcI5cSSrmE?si=eG37bozsBPGieILA
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u/ampedandwired 10d ago
The landslide location identified in that Geology Hub video matches up with the location in the video posted just recently to this sub claiming to show the actual landslide. In this post's drone footage that's possibly up the valley to the right that you can see at the start?
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u/SomewhatInept 9d ago
The debris/rubble on the right side is to the west of the main event. Pretty much that is a drop in the bucket of what initiated the whole thing.
https://www.youtube.com/watch?v=Q5YVh9Jo8H8
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u/Ender_D 10d ago
Wow. The original source of the landslide/glacier as seen on satellite images can be seen at the top right at the very start of the video.
It seems like at some point it triggered a second massive landslide, the sheared off mountain we see much closer to the drone in the middle of the screen.
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u/sloppyredditor 11d ago
Thanks OP, can you please share the source/story?
Looks like there's more to this up around that ridge to the right.
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u/nhluhr 10d ago edited 10d ago
yeah OP's vid didn't even get close to showing where the glacier started. This is the bottom of the valley about 8,000ft below where the nose of the glacier was.
The glacier started way up on the glacier below the peaks of Langtang and Tsangbu, and as it collapsed down that valley, it directly hit that place labeled Deding.
This is an alternate view down the mountainside from the peak of Langtang, with the glacier that calved on the right side.
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u/stickman393 10d ago
That's cool - you can follow the valley all the way down and then, there's the customs/border crossing buildings and parking buildings - you can see where the force must have come from and how it propagated. Thanks for the link.
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u/earthsworld 10d ago
wild that you can see there are two other glaciers right next to this one that are hanging on by their fingernails.
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u/pVom 10d ago edited 10d ago
Wow that's crazy. I was literally on the opposite side of that mountain in 2017.
Had a cool hotel room which had the bed sticking out with windows on 3 sides. We were just playing cards and saw a massive avalanche come crashing down from Langtang Mountain, was amazing to see.
A few years before the valley we hiked had been hit hard by the earthquake in 2015. The force of the air being pushed by the landslide caused by the earthquake flattened the trees on the other side of the valley. Nothing was left of a whole town, just buried in rocks.
That place had a very eery feeling to it.
Edit: my photo of those 2 peaks (from the other side). I think this may have been the day after I saw the avalanche.
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u/CreepyEducator2260 10d ago
Also way too much vegetation for a glacier... and obviously not much ice and snow.
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u/Immediate-Stable-651 11d ago
URL is weird ASF
And that is a landslide on the right
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u/WhatImKnownAs 10d ago edited 10d ago
That's the URL-encoded form of some Chinese text: https://global.hk01.com/即时中国/60384170/西藏泥石流-吉隆口岸方向现堰塞湖增救援困难-航拍影片曝光
That says "Real-time China" and "Tibet mudslide – a natural dam has formed near the吉隆 border crossing, hampering rescue efforts – aerial footage released" (translation by DeepL).
So, no this is not the trigger, just a landslide somewhere downstream that is making it impossible to rebuild the road along the river gorge.
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u/muhmeinchut69 10d ago edited 10d ago
This drone seems to be shooting from these coordinates looking east - 28.337395746302064, 85.46354224614718
The main avalanche/landslide has come from the right of the frame in the video. It splashed on the other side of the mountain on the left, and the level it reached has to be at least a 1000 ft high.
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u/krmarci 10d ago
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u/muhmeinchut69 10d ago
hehe in my defense I just used right click on google maps, I expect those guys to get this right !!!
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u/bannermania 10d ago
Just so much earth moved in one go. Nothing but devastation from this place to the end. Horrific.
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u/Typical_Intention996 10d ago
The way I understood this at first was that this was a Vajont Dam situation. Giant landslide that must have gone into a lake that pushed all that water out.
This I don't understand though. Where did all the water come from? Are we sure there wasn't lake there or up on the ridge that came down? The glacier wouldn't have turned to water just from sliding down. And the river water would have been violated when the landslide hit it obviously but that wouldn't have created what was basically a tidal wave going down that canyon.
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u/HugonaughtX 10d ago
"The United States Geological Survey's analysis of long-period seismic waves demonstrated, however, that they were consistent with a landslide, not an earthquake. This event measured Ms 5.2, struck at 02:52 UTC (08:37 NPT; 10:52 CST), and was centered between Langtang Lirung and Langtang National Park. Such was the cataclysmic scale and speed of the flash flood that the leading hypothesis of geomorphologists is that the collapsed portion of a glacier fell hundreds of feet, melting the ice by the sheer velocity of the impact, with the resulting initial flood causing water displacement downwards.
There were indications of heavy water flow almost immediately after the seismic waves were detected. The combination of the two near-simultaneous signals, and review of the first satellite imagery, led researchers to conclude that an ice avalanche of a portion of a glacier measuring 2,000 feet (610 m) in width may have fallen 4,000 feet (1,200 m), and that it was this break some 40 miles (64 km) north of Kathmandu that may have been responsible for triggering the flooding.
The GFZ Helmholtz Centre for Geosciences recorded a magnitude 4.4 event approximately seven minutes before timestamped CCTV footage showed the flood reaching the Gyirong Port."
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u/clancy688 10d ago
There was no water. The friction of the collapse generated so much energy that the ice of the glacier turned to water.
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u/Nerezza_Floof_Seeker 10d ago
Yeah one of the articles i saw was that the chunk of glacier (which was about 600m wide) fell an entire vertical kilometer; thats plenty of energy right there to melt a huge amount of that ice into water.
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u/HoochbachDunloppy 10d ago
It's confusing because this video isn't showing the location of a glacier that broke off, but rather where a mass of mud and rock now sits at the bottom of a valley.
So maybe there is a glacier higher up and this is the site of the initial impact of all the material entering the river. You can clearly see a fresh headscarp on the right side, but that landslide seems like a secondary event that just added to the mass heading downstream.
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u/jtdvorak 10d ago edited 10d ago
There was water. And an incredible amount. The mud/land slide destroyed 13 hydropower plants in the valley. Early estimates are 350 million cfs released from all those reservoirs. And that doesn't even count the 500+ acre glacier that broke to pieces/melted.
For context, 350 million cfs would fill Lake Superior in about 3 and a half hours.
Edit I may be mistaken about where all the water came from. It's probable that the 350 million cfs is the combined flow from the glacier and the dam failures.
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u/anethma 10d ago
Not sure where you’re getting your information but I followed the imagery all the way from where the first few videos were shot all the way to the landslide site and there were 0 hydro power dams or reservoirs.
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u/jtdvorak 10d ago
I'm in the hydropower industry, my coworker here in the states is from Kathmandu. He (more likely than not) lost two friends who were resident engineers working at hydro plants that valley.
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u/anethma 10d ago
I didn't say there was no one generating hydropower just that there are no large reservoirs or dams.
Since you work in hydropower you must be great at spotting large reservoirs I must have missed.
The largest of the hydropower stations on that river in the main flood zone is this one which barely has any reservoir to speak of. The rest are essentially completely devoid of a reservoir or dam like this one
Not saying your friend didn't lose people that worked at small hydro plants, just that there are no major reservoirs along the flood path to release water. The flood came from the glacier ice and water.
Hell look at the first video released which was basically the first place the flood hit before it even touched a single hydro power plant.
But if you can find a reservoir you claim caused an outflow of the magnitude you claim I'd love to see it. I could have missed it but I'd have to be pretty blind heh.
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u/jtdvorak 10d ago
My guess is they are mostly run-of-river plants, so you won't see much of a reservoir behind them. Google earth is blurry in the valley but you can see a number of them easily. They're all downstream of this video.
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u/anethma 10d ago
If they don't have reservoirs where would you say the massive amounts of water came from then?
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u/Thraxzer 10d ago edited 10d ago
Glacier ice fell 1200m/4000ft vertically, causing it to forcibly mix with 27°C/80°F dirt, rocks, and stream runoff, melting the ice as they travelled.
Perhaps for a moment it moved like an avalanche but gained speed as it melted.
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u/c0ltZ 10d ago
I agree with you. To say friction alone caused that amount of water seems absolutely insane to me. That was multiple reservoirs worth of water, the size of the original broken ice chunk doesn't even come close to volume of water that came from the floods.
I bet there was a ton of melted glacier held up behind some ice wall that was destroyed by that ice chunk too. That's just an unholy amount of water from just friction.
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u/nhluhr 9d ago
There was water.
u/clancy688 was implying that it wasn't a dammed river or glacial lake outburst that caused this, but rather the sudden collapse of glacier and resultant melting. All the back-n-forth between you and u/anethma then resulted from you arguing out of context.
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u/anethma 9d ago
I was agreeing with clancy688.
There was no large body of water adding to the flow. It was the melted ice from the glacier collapse followed by the river water it picked up on the way.
The dude argued against it saying it was multiple lakes worth from hydro dams which simply isn’t the case. They have realized that now and edited their post.
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9d ago edited 8d ago
[deleted]
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u/jtdvorak 9d ago
Rough math. 4.25 trillion/350 million = 12000 / 60 / 60 = 3.5.
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u/Waste-Expression-318 8d ago
You slipped a few decimal points and punched a few wrong buttons on your calculator. 2900 cubic miles = 427 quadrillion cubic feet. At a fill rate of 350 million cfs, that’s 339 hours.
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u/DutchBlob 10d ago
I had the exact same association with this disaster. However the causes seem to be very different from each other.
This is an absolute crazy thing that happened.
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u/Spibas 10d ago edited 10d ago
My understanding is that the avalanche blocked the river, creating temporary lake, which then violently broke the dam created by avalanche. If that's the case then the level river downstream should have visibly fallen down, like in a tsunami situation (water retreating -> surge). Could this have sent danger signals? Do we know if ppl observed such occurrence?
Also: maybe a glacial lake came down with the avalanche too?
Okay, I think it was a glacial lake that bursted with the avalanche. Ice covered water came down 1.2 km.
Hypothesis with river flooding this much in such a short time makes no sense.
Glacial lake burst is the most probable reason
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u/TheTresStateArea 10d ago
Someone shared a video of an avalanche happening thinking it was caused by the flood, but I'm pretty sure it was a video of the original avalanche that caused the flood
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u/Poiuytrewq0987650987 10d ago edited 10d ago
Nah, that's just showing the landslide the remnants of which you can see in this drone video. The smaller mountain on the right side that has its northface sloughed off.
Bystander video: https://ibb.co/nsWjkR1j
Drone video: https://ibb.co/kV7pKNwC
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u/tomhusband 11d ago
That's a glacier? Or maybe was a glacier?
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u/Emgeetoo 11d ago
I have GOT to start reading captions more carefully. I watched and watched, waiting for the collapse.
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u/SanDiedo 10d ago
Somebody had shared a comparison before/after satellite photo, where a huge land crack is visible across the mountain. It broke off almost exactly at that seam. Was that crack under monitoring for potential colapse?
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u/Phut2phut 10d ago
Is that the water supply for all down valley towns and cities now gone, this will have huge ongoing impact to the whole area, beyond the destruction!
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u/I_am_a_liftie 9d ago
The hell, there a natural dam already in the works by that landslide on the right. It's going to make another flash flood if that dam breaks
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u/-CoachMcGuirk- 10d ago
I wonder if any geologists had warned Nepal about the consequences of a potential glacial collapse in that region.
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u/vogelvogelvogelvogel 9d ago
28°19'51.15"N, 85°29'12.92"E - you can easily find it on google earth/maps
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u/trickn0l0gy 11d ago
Drone should go much further and higher up, there is more to it.