According to a seismologist investigating regional earthquakes, a northeast Ohio well used to dispose of wastewater from oil and gas drilling almost certainly caused a series of 11 minor quakes. Some environmentalists are already critical of the drilling method known as hydraulic fracturing, or fracking, which utilizes chemical-laced water and sand to blast deep into the ground and free shale gas. Critics fear that the drilling liquid contains carcinogens, and could contaminate water supplies. The industry-supported Ohio Oil and Gas Association, however, said the rash of quakes was "a rare and isolated event that should not cast doubt about the effectiveness" of injection wells, adding that the wells "have been used safely and reliably as a disposal method for wastewater from oil and gas operations in the U.S. since the 1930."

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