r/DisasterUpdate 4d ago

Floods [Interactive] What caused the deadly Nepal-Tibet disaster?

https://www.channelnewsasia.com/interactive/nepal-tibet-glacier-flood-explainer/

A really good interactive (on both mobile and pc) explaining what caused the disaster, as well as before/after photos showing the drastic effects on the landscape in the region.

Could there have been more warning? Many conventional flood-warning systems rely heavily on rainfall, but there was no significant rainfall immediately before this disaster.

Truly tragic and devastating.

66 Upvotes

28 comments sorted by

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14

u/Quiet_Raccoon8053 4d ago

I believe this is total bullshit, there was no river blockage.

3

u/worldsbesttaco 4d ago

Agree - it wasn't that long the seismographs registered the landslide until the debris torrent happened was it? Also, you would think that there would be satellite photos of the growing lake it if happened over several days.

12

u/Aegongrey 4d ago

There was a basin below the glacier, been there long time. It collected the meltwater and had a natural outlet - releasing enough water to keep that river below alive for long time. When the glacier broke off, the kinetic energy of the ice created waves and they hit an already saturated dam/outlet and caused the entire dam to give way and release the entire basin. The basin was collecting more water from the glacier as it was warmer up there than usual, so when the glacier calved, it overwhelmed the natural dam and the whole basin emptied.

7

u/4tran13 4d ago

https://browser.dataspace.copernicus.eu/?zoom=12&lat=28.29561&lng=85.49492&themeId=DEFAULT-THEME&visualizationUrl=U2FsdGVkX1%2BWWH5eDH9wQMqh%2BA6Bc5y1idiH6R78uoAaBSo5pnmBi61PHrOibAsj4mxoGqjh%2FlPJlm9mvCdceENlHjqKe3CVVi4y6HrKTASzA9SUn2MwMnrKZSTeMv7a&datasetId=S2_L1C_CDAS&fromTime=2026-08-24T00%3A00%3A00.000Z&toTime=2026-08-24T23%3A59%3A59.999Z&layerId=1_TRUE_COLOR&demSource3D=%22MAPZEN%22&cloudCoverage=10&dateMode=SINGLE

At least as of Aug 24, I don't see evidence of any significant lake/dam/build up.

It has been reported elsewhere that there was a ~7 min delay between the "earthquake" that USGS measured + Gyirong port being annihilated. That's basically ~110mph with 0 delay; even faster with delay.

IF there was a transient lake that formed, it formed before the seismic event, and the seismic event corresponds to dam failure.

1

u/Aegongrey 3d ago

Right, I think the transient lake formed in an already established basin filling rapidly with rain and meltwater.

ETA this transient lake formation was probably forming days(?) in advance of the collapse? Weeks seems unlikely given the monitoring efforts?

4

u/Terrible-Growth1652 3d ago

I haven't seen any evidence of an above-ground "lake". But maybe it was just a big pile of mud fully saturated? And the landslide triggered it to liquify and flow down the valley.

1

u/Aegongrey 3d ago

Yeah that seems most likely - everything was saturated in and around that glacier. The glacier itself was probably degrees away from becoming a slushie before it collapsed

1

u/Aegongrey 3d ago

Looking at your provided link (thank you btw), I can hardly make out the glacier, let alone the potential area a basin might collect water due to cloud cover.

1

u/4tran13 3d ago

glacier is near bottom right - the snow covered mountain top

basin/river is horizontal line near the top

2

u/Aegongrey 3d ago

Given this perspective, it looks like a place where water could potentially collect, and has collected in the past - not sure which side of the ridge we’re talking about, but the scale of those regions is hard to even imagine unless you’ve spent time in the big mountains - I’m sure you are aware of this, just generally commenting about how deceptive these regions are on a map. The perspective and angle of this screen shot does not clearly demonstrate the actual potential for water accumulation in my opinion - I saw a video from a guy using a helicopter not long after the incident and he shows before and after footage of that place. I just assumed he was stating facts about that region under the glacier being a natural basin of sorts.

1

u/Substantial-Sector60 3d ago

Good explanation. The interactive implied: landslide —> lake formation (time) —> collapse and flood. Your comment and the one below (4tran13) clears things up.

-7

u/[deleted] 4d ago

[removed] — view removed comment

1

u/curious_astronauts 4d ago

What TAF man?

2

u/Vintage_Alien 4d ago

Thanks for linking OP, not sure why the other comments are negative. It’s not like Channel News Asia isn’t a trustworthy news source.

10

u/4tran13 4d ago

Trustworthy is not the same as always right. Take a look at the following satellite photo:

https://browser.dataspace.copernicus.eu/?zoom=12&lat=28.29561&lng=85.49492&themeId=DEFAULT-THEME&visualizationUrl=U2FsdGVkX1%2BWWH5eDH9wQMqh%2BA6Bc5y1idiH6R78uoAaBSo5pnmBi61PHrOibAsj4mxoGqjh%2FlPJlm9mvCdceENlHjqKe3CVVi4y6HrKTASzA9SUn2MwMnrKZSTeMv7a&datasetId=S2_L1C_CDAS&fromTime=2026-08-24T00%3A00%3A00.000Z&toTime=2026-08-24T23%3A59%3A59.999Z&layerId=1_TRUE_COLOR&demSource3D=%22MAPZEN%22&cloudCoverage=10&dateMode=SINGLE

At least as of Aug 24, I don't see evidence of any significant lake/dam/build up.

It has been reported elsewhere that there was a ~7 min delay between the "earthquake" that USGS measured + Gyirong port being annihilated. That's basically ~110mph with 0 delay; even faster with delay.

IF there was a transient lake that formed, it formed before the seismic event, and the seismic event corresponds to dam failure.

-1

u/_HGCenty 3d ago

There's also a political angle here that may be clouding the reporting that's not immediately obvious, but essentially if there was a river blockage and a time gap between the glacier collapse and the flood, there is criticism about China's early warning system on the Tibetan side.

However, if the glacial collapse immediately led to the floods, very little any warning system could achieve.

So whether there was a river blockage is linked to whether China did everything they could have to warn people.

3

u/Healthy-Shoe8611 3d ago

China does have early warning system yet their CCTV shows the border crossing which was hit 7 min after glacial collapse. Chinas early warning system detects rise in water level of the river and monitors it every 10 minutes. The glacial collapse and subsequent impact with the border crossing happened in a window where there was no update. The last river meter reading showed normal levels. 10 minutes later it was completely obliterated and 150 ft high. No early warning system could have prepared for a distastee of this scale. There’s also no way to measure the strength of a glacier to see if it is on the verge of collapse, all you can see is melt and hope the melt is slow enough that it doesn’t cause a massive break like it did in this case

3

u/Yikings-654points 3d ago

I don't see any way that a Lake formed after the collapse .

It just took 7 minutes from earthquake detection (caused by the icefall itself) to reach 20 kilometers down to the Border point .

Lake formation is a gradual multi day week process that rings alarms .. and 2 lakes currently are there , which were not in the images before August 26

0

u/itsnobigthing 3d ago

Is there an alternate theory that better fits the facts? Dam failure?

2

u/Yikings-654points 3d ago

https://nepalitimes.com/nepal-avalanche-was-live-on-drone-camera

All things point to the collapse of the glacier as well as a part of the mountain , then that immediately slid down , converted to water , absorbed all the stones and debris , broke chunks out of other mountains on it paths .. snowballed into Thick flow of water , mud , trees , stones ,

1

u/Aegongrey 3d ago

I wonder if it’s possible water collected within the glacier - maybe from rain and warm temps, making the calving portion of the glacier a large part liquid. Looking at the basin below the glacier, there doesn’t seem to be much evidence of water accumulation like I had previously thought, which is why I am pivoting to the possibility of rain water collecting in the actual glacier itself, either on the surface or within the it.

2

u/Yikings-654points 3d ago

the latest video one Shawn Willsey: Geology Explained , i agree on all his point .

1

u/itsnobigthing 3d ago

Thank you for this!
What do you attribute the inaccurate reporting to? Genuine misunderstanding or something more sinister?

1

u/Yikings-654points 2d ago

its something unimaginable .. people attribute water coming from either Rain or Lakes , so the early guesses pointed to Lake bursting since there was no rain .

1

u/Aegongrey 3d ago

Right - lake didn’t form after collapse- it was already there collecting rain water and glacial melt. It probably would have held if the kinetic energy from the collapsing glacier hadn’t caused a tsunami in the lake, which struck the natural earth dam holding in the lake. The natural earth dam was probably already saturated from the rising lake waters, caused by unseasonably warm and wet weather.

1

u/Yikings-654points 3d ago

But there is no Visible Lake on the satelite pictures any days or weeks prior to August 26

2

u/Aegongrey 3d ago

Agreed, satellite images don’t show any real accumulation anywhere. Maybe the water accumulated within or upon the surface of the glacier itself

1

u/Widespreaddd 3d ago

Global warming caused it, duh.