NEW DELHI—Indian scientists are about to embark on an ambitious effort to drill into the Indian plate to monitor tremors and other seismic signatures of impending earthquakes.
Indian science minister Ashwani Kumar announced last week that the National Geophysical Research Institute (NGRI) in Hyderabad will launch a $75-million, 30-month-long project to drill an 8-kilometer-deep borehole in Koyna, a region in western India that experiences frequent small- to moderately-sized earthquakes. The borehole will be laced with sensors that measure chemical, electrical, and gravitational perturbations. "The Koyna site is ideal since a copious swarm of earthquakes, both induced and natural, occur all the time," says NGRI seismologist Harsh Gupta, the team's leader. The odds of observing signals of impending earthquakes, he says, are "very high."
The project, to be done in collaboration with the International Continental Scientific Drilling Program, will be the fourth such earthquake observatory. Similar boreholes have been drilled on the Kola Peninsula in Russia; in Bavaria, Germany; and on the San Andreas Fault in California. The earlier efforts all have taken place at the boundaries of tectonic plates; the Indian site will be the first intraplate borehole designed to look for earthquake precursors. Koyna is also unique because the borehole will be near a large dam, where the rise and fall of reservoir water levels frequently induces earthquakes.
Antinuclear activists worry that the drilling could increase regional seismicity and therefore increase the risk of a massive nuclear power plant in Maharashtra, 64 kilometers away. Roger Bilham, a seismologist at the University of Colorado, Boulder, dismisses that notion. "Drilling a hole will have no weakening effect," he says, "because the earthquakes in Koyna are in fact triggered by water in many thousands of water-filled cracks in the region. One additional hole is a drop in the ocean."