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Major rockslide hit hanging glacier, led to disaster: Scientists
A team of five scientists who visited the flash-flood site in Chamoli submitted its interim report to the institute’s director Kalachand Sain on Tuesday. It was the first team of scientists to visit the disaster site.
A huge rockslide may have crashed into a hanging glacier, forming an artificial water body and causing the glacier to crash a few kilometres upstream of the Rishi Ganga river in Uttarakhand’s Chamoli , spawning the deluge that devastated parts of the district on Sunday, according to the Wadia Institute of Himalayan Geology.
A team of five scientists who visited the flash-flood site in Chamoli submitted its interim report to the institute’s director Kalachand Sain on Tuesday. It was the first team of scientists to visit the disaster site.
Sain said the team of scientists led by Manish Mehta and Amit Kumar, who inspected the area on Tuesday, had tallied their ground observations with satellite imagery.
Giving details of the team’s findings, Sain said it all started at a peak known by locals as Mrighu Dhani, a few kilometres uphill of Raini village, the last human habitation in the upper reaches of Chamoli district.
“There was a hanging glacier,” Saini said, and on top of the glacier was a huge rock mass.
Because of freezing, thawing and temperature variation, the rock mass became loosened and came crashing down, creating pressure on the hanging part of the glacier.
“The fresh snowfall had also added to the weight over the hanging glacier also. And this hanging glacier broke off due to gravitational pull, slid down with the entire rock mass, all snow and took along more snow, debris, and boulders and soil.”
Sain said as the huge mass came down with force and slowed down near the base of the valley, where the Raunthi Gadhera stream flows. This stream receives waters from the glaciers.
“As the huge mass slowed a bit, then stopped, it blocked the water of the stream and the water quantum kept increasing. This damming up of the stream increased to such an extent that it breached the whole accumulated mass. The whole mass of water, boulders, and rock mass came crashing down with force towards the Rishi Ganga dam site,” he said.
The slush from Raunthi Gadhera stream, coming down with torrential force, washed away a hydropower project on the Rishi Ganga river and caused massive damage to the under-construction Tapovan hydel project. Until Tuesday evening, officials in Uttarakhand said 32 bodies had been recovered and another 174, who are missing, are feared dead.
Geologist Dan Shugar of the University of Calgary had hinted at a similar possibility on Monday, saying that a large rockslope (about 200 meters) became detached from a mountain and hit a glacier and brought debris to the base of the valley, where debris had already piled up from 2a 016 avalanche. He did not speak about the possible formation of an artificial lake.
Sain said it was not yet clear for how long the water had accumulated. “Prima facie it seems it was for a few days and then the breach happened. Our team is studying the area to get more details,” he said.
