With scientific evidence emerging that wastewater from oil and gas drilling is the possible cause of earthquakes, states are adding new requirements for disposal wells. Researchers think an increase in wastewater injected into the ground by drilling operators may be the cause of a sixfold increase in the number of earthquakes that have shaken the central part of the U.S. from 2000 to 2011, according to a U.S. Geological Survey study. The demand for underground disposal wells has increased with the proliferation of shale-gas drilling, a technique that produces millions of gallons of wastewater a well. Links between ... (full story)