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Journalism of Courage
Almost a week after cracks appeared in many roads and hundreds of houses of Joshimath, Uttarakhand, authorities on Sunday declared it a landslide and subsidence-hit zone.
The announcement came after a high-level meeting took place among the senior officials of the Central government, Uttarakhand state officials, and top officers from agencies including the National Disaster Management Authority (NDMA), Geological Survey of India (GSI) and the National Institute of Hydrology (NIH).
As of Sunday, 68 families have been evacuated to temporary relief centres and around 90 more will be evacuated soon, according to officials. The Indian Express takes a look at what land subsidence is and what might have led to the incident in Joshimath.
What is land subsidence?
According to the National Oceanic and Atmospheric Administration (NOAA), subsidence is the “sinking of the ground because of underground material movement”. It can happen for a host of reasons, man-made or natural, such as the removal of water, oil, or natural resources, along with mining activities. Earthquakes, soil erosion, and soil compaction are also some of the well-known causes of subsidence.
The US-based agency’s website also mentions that this phenomenon can “happen over very large areas like whole states or provinces, or very small areas like the corner of your yard.”
What can be the reasons behind Joshimath’s subsidence?
The exact reason behind Joshimath land subsidence is still unknown but experts suggest that the incident might have occurred because of unplanned construction, over-population, obstruction of the natural flow of water and hydel power activities. Not only this, the area is a seismic zone, which makes it prone to frequent earthquakes.
As The Indian Express reported, the possibility of such an incident happening in the region was first highlighted around 50 years when the MC Mishra committee report was published and it cautioned against “unplanned development in this area, and identified the natural vulnerabilities.”
According to experts, Joshimath city has been built on an ancient landslide material — meaning it rests on a deposit of sand and stone, not rock, which doesn’t have high load-bearing capacity. This makes the area extremely vulnerable to ever-burgeoning infrastructure and population.
Moreover, the lack of a proper drainage system might have also contributed to the sinking of the area. Experts say that unplanned and unauthorised construction has led to the blocking of the natural flow of water, which eventually results in frequent landslides.
As per the reports, residents have also blamed NTPC’s Tapovan Vishnugad Hydro Power Project for the incident. They allege that the tunnel had water seepage “from a punctured aquifer, leading to the drying of water sources in Joshimath.” Experts suggest that it could be one of the reasons for the collapse of the area.
However, NTPC denied the allegations and in a statement said, “The tunnel built by NTPC does not pass under Joshimath town. This tunnel is dug by a tunnel boring machine (TBM) and no blasting is being carried out presently”, according to a report by The Indian Express.
Apart from the aforementioned possible reasons, reports have pointed out that subsidence in Joshimath might have been triggered by the reactivation of a geographic fault — defined as a fracture or zone of fractures between two blocks of rock — where the Indian Plate has pushed under the Eurasian Plate along the Himalayas.
