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A gigantic landslide shows the limit to how high mountains can grow

economist.com

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Re: A gigantic landslide shows the limit to how high mountains can grow

#11

Post by gumby »

akiselev wrote: post #4

Before anyone gets excited, the landslide occurred in the 12th century or so :( I was all excited to plan a rock hounding trip to the Himalayas. I even sent out the Sherpa bat signal (it’s a silhouette of me shaving a Himalayan yak), only to find out I’m eight hundred years too late.

I can’t say I am sympathetic about you having missed this Himalayan landslide. If you dawdled, it’s not my problem.

But if you’re willing to travel to the Alps, here’s one from a couple of weeks ago: https://www.theguardian.com/world/2023/jun/16/huge-landslide...

Re: A gigantic landslide shows the limit to how high mountains can grow

#12

Post by mjb »

For comparison, this is between 4 and 5 times larger than the Osceola Mudflow (https://en.wikipedia.org/wiki/Osceola_Mudflow) that formed the 550km² of fertile plains around the south end of Puget Sound (near Seattle) and knocked a huge chunk out of Mount Rainier. If you drive from Auburn to Enumclaw, for example, notice how flat the land is and think about how that was hilly Cascade foothills and glaciated drumlins until 5500 years ago. The Osceola event was way bigger than Mt St Helens, and this one in the Himalayas was way bigger even that that.

Back-of-envelope, that Osceola event released about 10^19 Joules of energy*. The scale of these things is absolutely incredible.

According to my father, until around the time he was doing Geology at university (late 1960s), the consensus was that these kinds of events (and mass wasting more generally) were geologic processes that no longer happened (and hadn't really happened throughout the Holocene). I don't know the history in detail there, but it does seem true that only relatively recently we've had a real appreciation for how active Earth's geology still is.

* 4e15 cubic centimeters of material, 2 g per cc mix of rock and ice, mean elevation change 1000m

Re: A gigantic landslide shows the limit to how high mountains can grow

#13

Post by gumby »

jmclnx wrote: post #8

> As the rubble crashed down, the energy released would have been equivalent to around six times that of the Tsar Bomba Interesting, wonder if this Approx 1190 event had a global impact. https://en.wikipedia.org/wiki/Medieval_Warm_Period Seems that ended in 1250, coincidence ??

> … the energy released would have been equivalent to around six times that of the Tsar Bomba

But how does that compare to an Olympic swimming pool full of double decker omnibuses being dropped from the same height?

Re: A gigantic landslide shows the limit to how high mountains can grow

#14

Post by mjb »

mjb wrote: post #12

For comparison, this is between 4 and 5 times larger than the Osceola Mudflow ( https://en.wikipedia.org/wiki/Osceola_Mudflow ) that formed the 550km² of fertile plains around the south end of Puget Sound (near Seattle) and knocked a huge chunk out of Mount Rainier. If you drive from Auburn to Enumclaw, for example, notice how flat the land is and think about how that was hilly Cascade foothills and glaciated drumlin…

Related, there's a cool transition if you hike up the Greenwater river (starting at the town of Greenwater, heading towards FS70) there's a cool transition where the geology switches from Osceola mud to the more typical Cascade foothill geology (about half a mile from the White river).

Re: A gigantic landslide shows the limit to how high mountains can grow

#15

Post by trillic »

PNewling wrote: post #9
swader999 wrote: post #6

Article didn't mention it but lightning is a significant force in mountain erosion too.

I don't think I have ever heard of this, have any more details?

There's water in the rocks. When it rains water gets trapped between rocks and layers of rock.

Then a storm comes in, more water, water is flowing filling cracks, pooling wherever it can, lightning strikes, the water trapped in and around some of the rocks very quickly heats up, turns to steam, and kaboom, you now have moving rock.

Presumably lightning strike erosion is a lot of energy over a short time compared to wind or water erosion which is much less energy but over much longer periods?

Re: A gigantic landslide shows the limit to how high mountains can grow

#16

Post by defrost »

PNewling wrote: post #9
swader999 wrote: post #6

Article didn't mention it but lightning is a significant force in mountain erosion too.

I don't think I have ever heard of this, have any more details?

https://www.nationalgeographic.com/science/article/140105-li...

https://ui.adsabs.harvard.edu/abs/2016EGUGA..1815451H/abstra...

etc.

There are some high resolution nightside lighting storms from orbiting camera compilations on youtube that might impress just how much power zaps down in strikes.

Re: A gigantic landslide shows the limit to how high mountains can grow

#17

Post by farnsworth »

mjb wrote: post #12

For comparison, this is between 4 and 5 times larger than the Osceola Mudflow ( https://en.wikipedia.org/wiki/Osceola_Mudflow ) that formed the 550km² of fertile plains around the south end of Puget Sound (near Seattle) and knocked a huge chunk out of Mount Rainier. If you drive from Auburn to Enumclaw, for example, notice how flat the land is and think about how that was hilly Cascade foothills and glaciated drumlin…

Wild to think about the fact that there were people living there who would have seen (or been buried) by that. Same with some of the cataclysmic floods and other events that came with the end of the last ice age.

Re: A gigantic landslide shows the limit to how high mountains can grow

#18

Post by kennyadam »

gumby wrote: post #13
jmclnx wrote: post #8

> As the rubble crashed down, the energy released would have been equivalent to around six times that of the Tsar Bomba Interesting, wonder if this Approx 1190 event had a global impact. https://en.wikipedia.org/wiki/Medieval_Warm_Period Seems that ended in 1250, coincidence ??

> … the energy released would have been equivalent to around six times that of the Tsar Bomba But how does that compare to an Olympic swimming pool full of double decker omnibuses being dropped from the same height?

The lengths people will go to to avoid using the metric system!

Re: A gigantic landslide shows the limit to how high mountains can grow

#19

Post by jononomo »

akiselev wrote: post #4

Before anyone gets excited, the landslide occurred in the 12th century or so :( I was all excited to plan a rock hounding trip to the Himalayas. I even sent out the Sherpa bat signal (it’s a silhouette of me shaving a Himalayan yak), only to find out I’m eight hundred years too late.

Apparently there are records of a loud noise being heard as far away as Timbuktu in the 12th century.

Re: A gigantic landslide shows the limit to how high mountains can grow

#20

Post by dylan604 »

akiselev wrote: post #4

Before anyone gets excited, the landslide occurred in the 12th century or so :( I was all excited to plan a rock hounding trip to the Himalayas. I even sent out the Sherpa bat signal (it’s a silhouette of me shaving a Himalayan yak), only to find out I’m eight hundred years too late.

> only to find out I’m eight hundred years too late.

and I thought I was bad for missing the timezone and being an hour late to watch the ESA's Euclid launch. Besides, I was able to watch mine in replay.

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