Scientists believe that by working on such precursors, they would be able to develop a mechanism to predict earthquakes. In India, the National Geophysical Research Institute (NGRI) has been carrying out precursor studies for many years now and has even reported some success in predicting quakes under controlled conditions. But a comprehensive warning system is still some distance away.

NGRI director Dr V.P. Dimri, who has done extensive studies on precursors and authored a couple of books on the subject, says there are too many variables to be studied and not one can be said to be more reliable than the other.

“Changes in one or a few variables need not be conclusive signal of an impending earthquake. It’s much more complicated than that. But we can certainly build on a model by studying these variables,” Dimri said. “Moreover, even if we are able to develop a successful model, it is always going to be location specific. What works in Maharashtra might not work in the Himalayas,” he said.

Scientists at Dimri’s institute have, in fact, been successful in making accurate predictions under controlled conditions. Koyna Dam in the Western Ghats in Maharashtra is a region of continuous seismic activity and is a readymade laboratory to study earthquakes. In May 2006, NGRI, which set up nine monitoring stations near the dam, predicted a quake of magnitude 4 within the next 15 days in a radius of about 10 km from the dam. Just three days later, a quake measuring 4.2 on Richter scale struck exactly in the area predicted.

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