Induced shocks

  • 27/02/2001

Induced shocks The earthquake triggered by the Koyna dam sparked off the debate whether large reservoirs induce earthquakes. "That is the only example of reservoir induced earthquake in India,' says Harsh K Gupta, director of NGRI. The anti-dam lobby has been opposing the Sardar Sarovar dam and the Tehri hydropower project on this count. The former is situated near the Narmada fault that passes through Madhya Pradesh and the other is situated in the highly seismic Tehri Garhwal region.

Though much research has been done to study reservoir-induced seismicity (RIS), scientists still don't endorse this completely. In one study, 120 cases of RIS have been linked to some 300 large dams worldwide. Interestingly, the same study found small reservoirs more likely to be causing RIS. According to a section of seismologists, RIS is possible while for another section it is just a theoretical deduction.

"RIS can happen but sometimes a reservoir can help in curbing some specific seismic activity also,' says D K Paul, head of the earthquake engineering department of the Roorkee University. RIS is now regarded as an environmental and dam safety-related concern.

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