Alaska Glaciers

[HapHazard]

https://www.reddit.com/r/CatastrophicFailure/comments/15k3fmp/mendenhall_river_flood_ak_82023_timelapse_of_6/

^ timelapse video can be found there

[The Walrus]

Mendenhall Glacier near Juneau, Alaska, has started to periodically flood the Mendenhall River on which the city sits.

As water builds up in the basin and seeks an outlet, it can actually lift portions of the glacier ever so slightly, and in that lift, the water finds a release. Under the vast pressure of the ice bearing down upon it, the water explodes out into the depths of Mendenhall Lake and from there into the river.

Glaciologists even have a name for the process, which is happening in many places all over the world as climates change: jokulhlaup, an Icelandic word usually translated as “glacier leap.”

http://www.nytimes.com/2013/07/23/us/alaska-looks-for-answers-in-glaciers-summer-flood-surges.html?_r=1&

Indeed the very first post in this thread, posted 10 years ago by Sig, tells of the danger from Mendenhall glacier.

Glacial outburst floods occur annually at the Mendenahll glacier.  This one was just stronger that those previously. 

[vox_mundi]

The trees in the video at https://www.reddit.com/r/CatastrophicFailure/comments/15k3fmp/mendenhall_river_flood_ak_82023_timelapse_of_6/ are over 75 yrs old, indicating that a flood of this magnitude has not occurred there during that time. Outburst floods only began beginning in 2011.

Excellent Infographic ...

Hidden Water: The Suicide Basin Outburst Flood
https://www.arcgis.com/apps/Cascade/index.html?appid=ad88fd5ccd7848139315f42f49343bb5

Since 2011, the glacier-dammed lake in Suicide Basin above Juneau has unleashed floods into the valley below – sometimes in perfectly dry weather. Learn about the monitoring efforts and the history of this basin.

https://www.weather.gov/ajk/suicideBasin



2023 Last Two Week Time-Lapse Sequence With Vectors - A Drop of Over 80 Meters

Animated time-lapse sequence including velocity field with maximum height from 2022(red line) and 2021(yellow line). Color-coded arrows represent motion of the floating ice in the basin.



Maximum water level in the lake hit 14.97 feet late Saturday — which the NWS noted was "well above the previous record stage" of 11.99 feet, set in July 2016.

[solartim27]

All the news sites are showing the house collapse, not the scene 6 hours before the house went in.  You can't even see the house.

[John_the_Younger]

Ah, the dangers of building on a floodplain!  I, too, was surprised how far from the river bank the buildings had been.  Given the "floodplain or mountainside" options when building near Juneau, I'd go with the "floodplain but on stilts" option.  Would it have been enough?

I remember the story of a fellow geology student who set his tent on a flat-ish stream bench a couple meters above a foot-crossable stream (in the rain).  At some point in the middle of the night he felt something pushing on his feet - curious (there are no bears in New Zealand), he scanned the area with his torch (flashlight) and noted it was the stream, now a river, flowing on the terrace.  Fortunately, he could grab his backpack and just drag the (internal framed) tent to the next higher bench.

[RoxTheGeologist]

My professor at Oxford, Keith Cox, believed that the Vedic(?) civilization in India was lost because of an avulsion that changed the course of the Ganges river by several 100 km.

[The Walrus]

My professor at Oxford, Keith Cox, believed that the Vedic(?) civilization in India was lost because of an avulsion that changed the course of the Ganges river by several 100 km.

Have not heard anything that changes to the Ganges led to their decline, but much has been as to the fate of the Harappan civlization, immediately prior to the the Vedic civilization.  Much evidence points to the drying of the great Sarasvati River in eastern Pakistan.  Many settlements have been found in the the desert along a path that was likely the great holy river.

[kassy]

If it happened it was not in Alaska.