Flooding in Nepal - Glacier Collapse

[Point Conception]

TL;DR

Hundreds of Trekkers Missing in Nepal Flooding

https://www.yahoo.com/news/world/articles/foreign-tourists-missing-nepals-flash-155744585.html.

 

[gmax137]

The videos are terrifying.

 

[256bits]

You might want to factual check for sensationalism in this one paragraph:

Equations
1. Potential Energy of 1 kg of water at height
E = m g h --> mass 1 kg, g = 9.81 m/s/s, h = 1200 m ( Assuming 1200m as height, and not glacial path length )
E = 11.8 kJ

Temperature rise of 1 kg water from heat addition Q
dt = Q / ( m Cp ) Q = 11.8 kJ, , = 1 kg, Cp = 4.2kJ / ( kg C )
dt = 2.8 C

Edit:
dt = Q / ( m Cp ) Q = 11.8 kJ, , = 1 kg, Cp = 2.050 kJ / ( kg C )
dt = 5.76 C


I would take the 2.8 C 5.76 C temperature increase due to conversion of potential energy to heat energy to mean that the chunk of glacier ice had already approached melting temperature, lost its cohesive strength and broke away, travelled down the glacial valley on the incline ( not straight down ) and completely liquified into a slush ( ie disintegrated into a mixture of ice particles and water ) during decent.

Reaching warmer temperatures along the path 50 km further down the valley, all of the slush would become water.

 

[Greg Bernhardt]

The videos are terrifying
https://www.nytimes.com/2026/08/26/world/asia/nepal-flood-glacier-ice-avalanche.html

Unfortunately I think we'll see more of this with glaciers continuing to melt.

 

[Andy Resnick]

TL;DR: Hundreds of Trekkers Missing in Nepal Flooding

https://www.yahoo.com/news/world/articles/foreign-tourists-missing-nepals-flash-155744585.html.

The videos are terrifying.

The videos are terrifying
https://www.nytimes.com/2026/08/26/world/asia/nepal-flood-glacier-ice-avalanche.html

Agreed- I have never seen anything like that.

 

[Point Conception]

You might want to factual check for sensationalism in this one paragraph:

View attachment 373873

If the mass of the glacier that fell is estimated to be 5 000 000 000 kg from 1200 m then v =153 m/s. And with KE = 1/2 mv^2 . joules at impact= 58x10^9. The phase change from ice to water=334000 joules/kg. So only about 173,653 kg of ice converted to water at impact.

[Mentor Note: Some AI content has been deleted out of this post since the thread is in the technical forums]

 

[256bits]

If the mass of the glacier that fell is estimated to be 5 000 000 000 kg from 1200 m then v =153 m/s. And with KE = 1/2 mv^2 . joules at impact= 58x10^9. The phase change from ice to water=334000 joules. So only about 173,653 kg of ice converted to water at impact.

Right. I incorrectly used the Cp for change in degree for water, instead of that for ice.

Equations
1. Potential Energy of 1 kg of water at height
E = m g h --> mass 1 kg, g = 9.81 m/s/s, h = 1200 m ( Assuming 1200m as height, and not glacial path length )
E = 11.8 kJ

Temperature rise of 1 kg water from heat addition Q
dt = Q / ( m Cp ) Q = 11.8 kJ, , = 1 kg, Cp = 2.050 kJ / ( kg C )
dt = 5.76 C

The chunk of ice would have risen in temperature of 5.76 degrees C from the drop.

And then there is the phase change to water, as you have expressed.

Post #3 edited

 

[sbrothy]

The videos are terrifying
https://www.nytimes.com/2026/08/26/world/asia/nepal-flood-glacier-ice-avalanche.html

Unfortunately I think we'll see more of this with glaciers continuing to melt.

It sounds so bad I serioulsy don't want to look!

 

[256bits]

Some discussion from Jakob Steiner, a geoscientist at the University of Graz in Austria
and Glaciologist Simon Cook, University of Dundee, Scotland.




Satellite image at the 1:42 mark.

 

[256bits]

Some video of the deluge. Viewer beware.
( I find she babbles a bit much, but that's just me, 229 subscribers she has )



1. Question of where all the water came from.
2. Blocked lake upriver posing a risk of secondary water cascade
3. Seismic recordings were that of the deluge ( not an earthquake in the normal sense )

 

[Point Conception]

If the mass of the glacier that fell is estimated to be 5 000 000 000 kg from 1200 m then v =153 m/s. And with KE = 1/2 mv^2 . joules at impact= 58x10^9. The phase change from ice to water=334000 joules/kg. So only about 173,653 kg of ice converted to water at impact.

[Mentor Note: Some AI content has been deleted out of this post since the thread is in the technical forums]

Correction the joules at impact with 5000000000 kg ice falling 1200m: KE = 1/2 mv^2 = mgh = 5.8 x 10^13 joules. So with 334000 joules/kg ice to water phase change. About 176 000,000 kg ice converted to water at 0 degrees C at impact. Out of 5000,000,000 kg ice in glacier. *** Of course all this is kind of hand wavy since the glacier contains other material in the total mass . And some of the kinetic energy at impact is going to displace material at impact location