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'Sikkim quake may have been induced by dams across Teesta'

india Updated: Sep 21, 2011 21:10 IST

Professor Jeta Sankrityayan, former member State Planning Board, West Bengal and also a member of the landslide expert committee 1998, has opined that the presence of multiple dams on the river Teesta and its tributaries could either induce or accelerate earthquakes.

“In early 1970 a major earthquake in Maharashtra had been triggered by the Koyna dam located on the Sahyadri Hills. Though the role of the dams on the River Teesta in the recent quake is yet to be studied, the earthquake could have been induced or accelerated by the dams (dam induced seismicity )” feels Sankrityayan.

The committee on landslides, which had also studied the tectonic plate movement, had handed over recommendations to the government of West Bengal in 2000. The committee had recommended that no constructions should be allowed on the rivers.

The Central government’s “master vision” identifies the North-Eastern region as “India’s future powerhouse” by building about 168 dams in the region. To do this, the Teesta river in Sikkim is being extensively dammed.

Around 35 hydel power projects have been identified in this region with the Teesta Low Dam (TLD) project being the most prominent. The TLD project, harnesses the Teesta river, which originates in Sikkim and flows through North Bengal, creates a 332 MW capacity split into four stages.

The first two stages for a total of 100 MW are in Sikkim, while stage III of 100 MW and stage four of 132 MW are in West Bengal.

“It is very unfortunate that the Government does not pay heed to recommendations of its own committee for which the public have to suffer. Something more devastating can happen any day. It is time the public woke up and pressurized the Government to act more reasonably. Electricity in lieu of lives is not a very human option” added Sankrityayan.

The Himalayas are a young chain of mountains formed by the Indian tectonic plate colliding with the Eurasian plate.

While the river Teesta flows in a north-south direction, the Himalayan fault lines lie in the east west direction.

“A major fault line is located at Kalijhora (considered the best location to study Himalayan fault lines) and Teesta Low Dam Stage 4 is located at Kalijhora” stated Sankrityayan. Bad weather disrupts rescue work

Explaining dam induced seismicity, Sankrityayan stated that owing to the dams checking the flow of the river, the water becomes heavy and starts going down, usually seeping into crevasse.

“Water being a new element in the faults and crevasses in the mountain, the mountain starts adjusting which causes the seismic movements” stated Sankrityayan. The very flow of Teesta is an indicator of the fault line.

While in Sikkim the Teesta flows is curves (zig zag) after Teesta Bazar in West Bengal it flows in a straight line which suggests that it could be flowing along fault line in West Bengal.

“Very few earthquake movements are in a North-South direction but the 6.8 magnitude quake which hit Sikkim and this region was in a North-South movement. The epicenter was at the base of Mount Kanchenjunga. The mountain moved.”

“It took a mere two seconds for the earthquake to reach North Bengal University near Siliguri in the plains from Gangtok which is very unusual” stated the Professor. The shake intensity recorded was 7 Mercalli in Mangan, 38 km from the epicenter and 7 Mercalli in Siliguri 144 km away from Mangan. Gangtok too recorded a shake intensity of 7 Mercalli “ stated Sankrityayan. Sikkim toll now 73

“A full scale inspection and study should be conducted by geologists and earth scientists into the recent quake and on the dam induced seismicity. It should be an independent probe not influenced by the Government. We should not be accelerating or bringing in such natural events otherwise we will definitely have to pay a dear price” suggested the Professor.