DEHRADUN: A variety of factors both anthropogenic and natural have led to the subsidence of Joshimath, director of the Wadia Institute of Himalayan Geology Kalachand Sain said on Friday.
The factors are not recent, they have built up over a long period of time, he said.
The three principal factors are Joshimath's vulnerable foundations as it was developed on the debris of a landslide triggered by an earthquake more than a century ago, its location in seismic zone V which is more prone to earthquakes besides gradual weathering and water percolation which reduce the cohesive strength of the rocks over time, Sain told PTI.
Atkins had first written about Joshimath's location on landslide debris in the Himalayan Gazetteer in 1886.
Even the Mishra Committee in its report in 1976 had written about its location on an old subsidence zone, he said.
The going down of the Himalayan rivers and heavy rainfall which is characteristic of the area beside the flashfloods in Rishiganga and Dhauliganga rivers last year may also have worsened the situation, he said.
As Joshimath is the gateway to Badrinath, Hemkund Sahib and skiing destination Auli haphazard construction activities have been going on in the area for a long time without thinking about the pressure the town is capable of coping with, he said, adding this may also have led to cracks appearing in the houses there.
"Hotels and restaurants have mushroomed everywhere.
The pressure of population and the size of the crowd of tourists has also increased manifold," he said.
"Many houses in the town are unlikely to survive and people living in them must be shifted to safe locations as life is precious," he said.
After the evacuation of people in affected areas to safety, microzonation of the town, replanning of its drainage system and rainwater outlets besides assessment of rock strength among others should be undertaken, Sai suggested.