Oklahoma earthquakes force 7 more disposal wells to be shut down, another 66 to reduce volumes

Oklahoma regulators have responded to another rash of earthquakes by ordering seven disposal wells to be shut down, Mike Soraghan reports for EnergyWire. "The Oklahoma Corporation Commission directed the owners of 66 other wells to reduce volumes by 25 to 50 percent. Operators of another 67 disposal wells were told to prepare for possible changes to their operations."

"Northern Oklahoma was shaken Monday afternoon by the second magnitude-4.7 earthquake in two weeks," Soraghan writes. "It was centered west of Medford but was felt as far away as Iowa. The first occurred the morning of Nov. 19, centered near Cherokee. It was the largest quake since the aftershocks of the state's largest-recorded quake, a magnitude-5.6 quake near Prague in 2011 that destroyed 16 homes and injured two people. In November, the state had 68 earthquakes of magnitude 3 or larger. This year, it has had more than 800, a substantial increase over the 585 in 2014."

"Scientists say the unprecedented swarms of man-made quakes in the state since 2009"—Oklahoma averaged two earthquakes of magnitude 3.0 or higher per year before then—"can be attributed to favorably aligned faults and production methods that create uniquely large volumes of wastewater," Soraghan writes. (U.S. Geological Survey graphic)