KASARGOD: Get ready for some earth-shaking news. Kerala has turned into a reservoir-induced earthquake prone state because of the high number of dams dotting the Western Ghats, John Peruvanthanam, convener of the Paristhithi Samrakshana Ekopana Samithi (Coordination Committee for Environmental Protection), told Express.Quoting a study conducted by the Samithi, he said there are 55 big dams and 200 small dams between Malampuzha dam and Thenmala dam, an aerial distance of 124 km. “And between these dams, there are 16,000 quarries,” he said.
Several scientific studies have linked tremors to reservoirs. “Around 65 earthquakes were reported from Idukki every year in 2002, 2003, and 2004. They cannot be tectonic-linked as tectonic earthquakes are well spaced,” he said.Micro-cracks in grounds would turn to water pillars because of the heavy water pressure in dams. These pillars would in turn lubricate the faults already under tectonic strain, causing tremors, said John.
The government is proposing more dams because it had no idea on the geo-physical structure of the Western Ghats, he said. “The Western Ghats cannot take the burden of more dams. And that is why projects such as Athirappilly should be abandoned,” he said, adding old dams should be decommissioned.
According to scientists, reservoir-triggered earthquake is a well-observed phenomenon all over the world. But more studies are needed to conclude the Western Ghats had been turned to a tremor-prone zone because of dams.
“Dams in areas which are under tectonic stress will hasten the release of that stress,” said N Purnachandra Rao, director of the government-run National Centre for Earth Science Studies, Thiruvananthapuram. But they would be minor tremors, said the senior scientist with several published papers on Koyna dam-triggered earthquake in Maharashtra.The 6.3 magnitude earthquake on December 11, 1967, flattened the village of Koynanagar, killing around 180 people, injuring 1,500 and rendering thousands homeless. “It is the most powerful earthquake induced by a reservoir in the world,” he said.
The similarities between Koyna dam and those in Kerala are few except for the fact it is also in the Western Ghats, Rao said. The dams are actually triggering smaller less-damaging tremors instead of a big earthquake sometime in the future. “In a way, that is good.”Another scientist of the same institute said the earthquake behaviour over the past 10 years in the region will attest to reservoir-induced seismicity. But to claim the entire Western Ghats is not suitable for dams would be incorrect, he said. Both scientists said reservoirs are necessary to meet the energy and drinking water needs of the country.
Social unrest
According to the study by the Samithi, 80 per cent of the Western Ghats in Kerala is owned by 2 per cent of the people. Of the rest, 11 per cent belongs to the government. “That leaves just 9 per cent of Western Ghats for 98 per cent of the people,” said John. Quoting the same study conducted over a long period, he said there are 48 lakh people living in 36,000 Dalit colonies in the Western Ghats. Each colony has around 20 to 200 families and they own between 1.5 cents to 10 cents. “This injustice will create huge social problems in Kerala,” he warns.
Western Ghats Raksha Yatra
Led by John, a Western Ghats Raksha Yatra was flagged off at Kasargod on Wednesday by lawyer and activist Prafulla Samantara. The rally will culminate in Vizhinjam, Thiruvananthapuram, on October 16.
During the campaign the Samithi will make 200 stopovers and it will include film screenings, photo exhibition, street play and music concert.
tectonic threat
Earthquake behaviour over the past 10 years in the region will attest to reservoir-induced seismicity Around 65 earthquakes were reported from Idukki every year in 2002, 2003, and 2004
population spread
80 per cent of Western Ghats is with just 2 per cent of population. Of the rest, 11 per cent belongs to the government. That leaves just 9 per cent of Western Ghats for 98 per cent of the people
124 km of the Western Ghats in the state has 255 dams
16,000 quarries between these dams
Tribespeople have landholdings of just 1.5 cents to 10 cents in the belt