An aerial view of Tapovan barrage on Tuesday, February 9, 2021, two days after a portion of the Nanda Devi glacier snapped off,
@planetlabs has updated image of #UttarakhandDisaster. Looks like massive dust deposition over much of W side of the valley and the trigger appears to be the landslide scar. Not a glacial lake outburst flood.
Oh this is brilliant. You can see a direct comparison of before and after pictures at https://www.planet.com/gallery/#!/post/rishiganga-rockslide-and-flood Move the central slider to compare before and after.
https://blogs.agu.org/landslideblog/2021/02/08/chamoli-2/
The catastrophic landslide and flood in Chamoli in Uttarakhand: the sequence of events
Deciphering the sequence of events that lead to the terrible debris flow / flood in Chamoli yesterday was quite a challenge, especially on a Sunday. However, a combination of the willingness of a number of people to use their expertise, and the availability of daily satellite imagery from Planet Labs, meant that we had the sequence determined within 8 hours of the event. This is remarkable – the landslide occurred in a very remote location, and the infrastructure was severely damaged. It took us a few days to understand the 2012 Seti landslide in Nepal, which was similar to this one. Now we can do this in a few hours.
So, for clarity, I thought it would be helpful to lay out the sequence events. I am going to lean heavily on Twitter, but these tweets come from a combination of world experts and citizen scientists. I have no doubt that this is the true story of what happened, but there are details to understand still. For a few months a large failure had been developing in the high mountains. Although we did not detect it, high in the mountains at 30.339, 79.731 a large crack was developing on the flank of one of the high peaks over a few months. I believe that this is Trisul, but there is some uncertainty about the names of the peaks. It is now clear that this mountain was Nanda Ghunti. This crack was detected after the event in a sequence of Sentinel satellite images by Julien Seguinot. At the end of the sequence the unstable block is clearly visible:
Before
After
> I think we can see the #Chamoli / #UttarakhandDisaster crack opening on these @CopernicusEU #Sentinel2 images (27 Jan to today). It points to a #landslide indeed.
Latest rescue news from France. https://www.france24.com/en/asia-pacific/20210211-authorities-in-india-begin-drilling-in-attempt-to-rescue-workers-trapped-in-tunnel
Indian authorities on Thursday began drilling inside a tunnel in the Himalayas in an attempt to rescue more than 35 workers trapped there after a flash flood that destroyed dams and bridges.
About 171 people remain unaccounted for since Sunday’s disaster in Uttarakhand state, most of them workers at the Tapovan Vishnugad hydroelectric project and at the smaller Rishiganga dam, which was swept away by the torrent.
So far, the bodies of 33 people have been found, the state police chief’s office said.
While scores are thought to have been washed away as rock and debris surged down the Dhauliganga River, rescue efforts have been focused on saving an estimated 35 workers stuck in a 2.5 km tunnel connected to the Tapovan project.
But the slush and water has been so heavy that soldiers have made only halting progress in four days.
After clearing more than 100 metres of mud, rocks and debris, relief workers on Thursday sent water tankers and generators deep into the tunnel to assist in drilling.The men are trying to search for signs of life in smaller tunnels and rooms branching off from the main passage, officials said.
Relatives continued to arrive at the site, but five days after the disaster, there was frustration at the lack of progress.
“They are not telling us anything,” said Praveen Saini, whose nephew, Ajay Kumar Saini, is trapped in the tunnel.
Another was holding onto hope that his brother had survived after he was able to ring his mobile.
