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Joshi Mutt crisis due to landslides, not subsidence: experts

World NewsIndia NewsJoshi Mutt crisis due to landslides, not subsidence: experts

The extensive damage to buildings and other structures in Uttarakhand’s Joshi Mutt is due to a gradual but rapid landslide, not the ground collapsing, a new analysis by a geoscientist has suggested.

“There is no doubt that this is a landslide, with a large mass moving down the slope,” Dave Petley, vice chancellor of Hull University in the UK, wrote in his American Geophysical Union blog on January 23. Google Earth imagery clearly shows that the town is built on an ancient landslide.

This could have implications for the extent or size of the area potentially affected by sliding, which could be larger than the area previously thought to be subsiding, he said.

A leading Indian geophysicist agreed with this view. “Landslides occur in slope area. It involves both vertical and horizontal movement, but in subsidence there is downward vertical movement. It is a case of terrain sliding,” said Kalachand, director of the Wadia Institute of Himalayan Geology. Sain said.

Sain flagged on January 14 that it might be wrong to call the Joshi Mutt crisis a case of land shortage.

Petley based his theory on an analysis by the Center for the Study of the Biosphere from Space (CESBIO), which used the Alaska Satellite Facility’s Vertex web portal for information about Josimoth.

“The rate of deformation increased sharply in October 2021, but there is an indication in the data that it may have started earlier for the point closer to the river,” Petley wrote in his blog. “This may support the suggestion that reactivation of this landslide was caused by toe erosion, but without further detailed investigation this is speculation.”

According to Sen, there are many factors that may have contributed to the sliding.

“Currently, we are doing geophysical studies to see how subsurface factors have caused cracks on the surface. Peer’s erosion after the February 2021 flood is one of them,” he said. “But there are many others, which we may soon be able to identify with certainty.”

Sain said snowfall and inclement weather in the area is affecting data collection. “In a slope area, landslides can be caused by three to four reasons. Rainfall can be a trigger, tectonic movement is another and the third is human-caused or anthropogenic activity. All three are likely,” he added.

He said that sliding is being seen in Joshi Math city with different intensities. “Some areas have been less affected, while some have been more severely affected. As soon as we have data, we can say how big a sliding could be in an area,” he said.

According to geologists SP Sati and Navin Joyal, who went to visit Joshimath to document and investigate the crisis, there are signs of both subsidence and slippage.

“We are seeing subsidence and creep in several pockets mainly in Joshi Math, which has the biggest impact on the central zone. The former scientist at the Physical Research Laboratory and the Supreme Court to review the Char Dham road projects. Joel, a member of the expert panel, said, “We are still reviewing the factors.”

“The core zone needs immediate evacuation and rehabilitation in a dignified manner, providing all basic amenities to the displaced people,” Joyal added.

Monday’s erosion is very clearly linked to the construction of the Hailong Bypass under the Char Dham Project. If it was known all along that the area was so prone to landslides, how could the government develop it into a high tourism zone with mega projects around it? asked Mallika Bhanot, an environmentalist and member of the civil society collective Ganga Ahvan. “There are blasts and tunnels going on, a rail project coming up and the Char Dham project cutting through a very fragile, landslide-prone area. How?”

On January 18, Petley cited a new InSAR analysis that used radar images to map land deformation. The analysis indicated that the defect in Joshi Math is slipping, not decreasing.

“The analysis shows that three segments of the landslide complex are currently advancing with the highest rate towards the lower part of the slope,” they wrote. “The limits of movement coincide with the margins of landslide blocks that are detectable from Google Earth. We would expect to see the greatest amount of damage to buildings around these margins.

Data generated by CESBIO indicates gradual sliding/land surface displacement of Joshi Math city since 2018. Joshi Mutt is situated between two major tectonic faults – the Munsyari Thrust and the Vikrita Thrust in the south. It is on a high seismic zone (zone 5).

“The Joshi Math was built on the debris of a landslide that happened several hundred years ago. I am not a geologist but from geoscientists I understand that the area is slowly collapsing due to several reasons – this land Vulnerable to sliding and weakened and due to development pressures. Slip and fall is uneven now but a large area is likely to be affected. We urgently monitor various geological factors of the Himalayas especially in these areas. Where there are large populations. Currently this is not happening. But the government should start serious and continuous monitoring to prevent future occurrences,” said M Rajeev, Secretary Earth Sciences.


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