Comment by delichon
9 hours ago
I don't think I've seen a snuff film of that scale before. I'm not good with even fictional horror. This may haunt my dreams. For most of the people there was just nothing they could do. But others would have had a chance if they had run perpendicular to the flow and climbed like their life depended on it. I'll try to remember that the next time I'm fleeing in panic from a flash flood.
Looks like a warning siren could have saved some lives. But apparently this was a black swan.
| But apparently this was a black swan.
What is your definition of black swan? This paper is from 2022 and scientists have been warning about climate change for decades. It's not like this possibility wasn't anticipated. It seems likely we'll see more glacial events as the atmosphere warms.
There have been maybe three such events in the 21st century (glacier or landslides producing more than a magnitude 5 quake), and none of them have happened in an area like the Himalayas. The other two were in Alaska on Mt Steller in 2005 and the Lamplugh Glacier in 2016, neither of which produced massive downstream floods.
It usually takes entire icebergs calving off to produce such seismic events and intense monsoons to create such flooding.
> There have been maybe three such events in the 21st century
It seems that past history (especially recent) will not be a good predictor of future events.
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Anticipation is one thing, effective response in the seconds before disaster strikes is quite another thing. This might not have been an absolute black swan, but even with foresight it is challenging in the extreme to avoid risk.
I've been reviewing what coverage I can find of the present event in Nepal/China, in context with Section 5.1, "Comprehensive approach to disaster risk management", of TFA.
It seems that what would be required would be:
- Active surveillance of glacial lake formation.
- Active mitigation of glacial lakes, reducing risk.
- Warning and response infrastructure, procedures, and protocols along the likly flood path.
From video of what I presume are among the worst-hit areas (see: <https://twitterwebviewer.com/?tweet=2092542957060841592>), there appear to have been at best a few seconds of warning. Very robust structures are demolished virtually instantly. Even had people been sheltering within those structures, or headed up-slope above the water flow, either structural integrity would prove insufficient, or response time inadequate to reach a safe elevation above the debris flow. The latter problem is compounded by what appears to be an extraordinarily strong air blast (likely hurricane-strength or greater) as well as massive amounts of airborne debris, much of it rock.
Terrain is severely constrained in the region, and the only buildable regions are in river valleys themselves. The Gyirong Port border crossing is located deep within a river channel, and despite robust construction simply could not survive the event.
See:
<https://en.wikipedia.org/wiki/Gyirong_Port> (Wikipedia article on the port.)
Map / satellite view: <https://www.google.com/maps/@28.2792579,85.3752907,1341m/dat...>
(Take a few minutes to examine the region around the port itself ... there are several communities and businesses all well within the disaster zone, and I suspect that obliteration to those matches or exceeds what was captured on video at the crossing itself.)
From the first video at this Twitter post, a camera situated roughly 20m above the base terrain did not survive the event (though it transmitted for roughly a minute).
A second camera (I believe near the same location) shows similarly catastrophic damage, and no chance for anyone at base level to climb to a safe elevation before being overtaken by the debris flow.
Wikipedia notes "Floodwaters reached settlements as high as 270 feet (80 m) above the river level", citing <https://english.onlinekhabar.com/rasuwa-flood-in-pictures.ht...>.
Climbing that far would require 4--8 minutes for even a highly-fit person. Available response time in the videos I've seen is on the order of 1--2 minutes. Anyone beginning within the debris zone is already walking dead.
As the Cowboy Junkies said:
Anticipation isn't sufficient. Other than entirely abandoning such locations during all periods of high risk, loss of life is likely, and catastrophic property and infrastructure damage inevitable.
<https://twitterwebviewer.com/?tweet=2092542957060841592>
When I was researching this morning I found papers related to this kind of risk from at least 2000. Given 20 years there could have been things done I think. And there is a lot of settlement on the tops of the ranges in that area too.. Maybe the roads have to be on the river valley, but not everything else. People living there could have been offered alternative land to move out of the path of it.. monitoring and early warning could have been set up.. at the checkpoint, if it had to be there, there could have been a big evacuation tunnel carved into the hillside, or something.. I guess Nepal doesn't have a lot of resources though. The same thing even happened a year ago in the sample place, but at a smaller size https://www.stimson.org/2025/investigating-an-emerging-clima...
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Perpendicular is not the scientifically best path. 45 degree angle is the best angle if the threat is moving toward you at the same velocity that you can move. As the velocity of the threat increases, the angle gets closer to perpendicular. The size of the threat and distance of course matter as well. I think about this before tree felling. In chainsaw classes they teach you to move at a 45.
Looking at the footage, the water/avalanche was moving far faster than anyone could move on foot. Well over 100 km/h, I would estimate.
Likewise if your car stalls on a railroad crossing, run at a 45 degree angle toward the train. This puts you away from the path of flying debris.
There was another similar flood on the same river about a year or two ago. The problem was the the glacial flooding started in Tibet and affected people just over the border (one of the videos is from the border crossing). There's no international data sharing for this sort of thing between China and Nepal and Nepal can't deploy sensors in Tibet to give sufficient warning.
We have tsunami warnings all the times now. Nobody is stopping people from burying sensor posts upstream.
I wonder if the river went dry first, like the water receding off into the horizon before a tsunami?
It is possible if you consider madaxe_again's theory(comment here). If the debris just started descending without interruption, there would be no receding.
Well supposedly it was caused by a landslide blocking the river for a few minutes, then the dam burst all at once.
The great flood myths across the world are quite possibly ancestral memories of this kind of flood on a continental scale. Retreating ice age glaciers would make lakes the size of states held at bay by an impromptu dam of various kinds of debris (or more glacier) which then would break dumping great lake amounts of water hundreds of miles into the ocean within days. This kind of thing probably happened in lots of places.
You just pushed me into a rabbit hole called the Zanclean megaflood.
https://en.wikipedia.org/wiki/Zanclean_flood
The Missoula Floods in the northwestern US were a similar sort of event, though I'm not sure how the scale compares.
https://en.wikipedia.org/wiki/Missoula_floods
Yes this is exactly the kind of thing i'm talking about and in the time frame which is at least plausible to make its way through mythology to modern day (not so much for the flooding of a dry mediterranean sea five million years ago)
It is supposed that such an event happened, when the land between continental Europe and England got flooded. This was as well during a warmer period when glacier melted. And there was human population on that land.
https://en.wikipedia.org/wiki/Doggerland
Oh there's geological evidence of these things happening in the pacific northwest, the waves and water scouring the landscape in an unimaginable fashion left evidence to be seen today. Like 1000 Niagra falls for a month straight. Outflows measured in billions of gallons per second or 10+ cubic kilometers per hour.
https://en.wikipedia.org/wiki/Channeled_Scablands
I think the Japan tsunami videos showed as many, but it was spread out over the course of almost 2hrs and happened in slow motion over a large area. You could see some cars speeding to safety while others were washed away. Some stayed in taller structures assuming they were safe and were slowly washed away.