Seismic security

Oklahoma quake prompts shutdown of gas-linked wells

Oklahoma regulators on Saturday shut down 37 wastewater wells connected to oil and gas production after a magnitude-5.6 earthquake — matching the strongest quake ever to hit the state — jolted north-central Oklahoma.

Some parts of Oklahoma now match Northern California for the nation’s most shake-prone, and one Oklahoma region has a one-in-eight chance of a damaging quake in 2016, with other parts closer to one in 20.

The quake, centered in rural Pawnee County, could be felt over a seven-state area, the U.S. Geological Survey reported.

Gov. Mary Fallin said on Twitter that the shutdown was a "mandatory directive" covering 725 square miles in Osage County, just northwest of the quake's epicenter. She said the Oklahoma Corporation Commission, which ordered the shutdown, was in touch with the Environmental Protection Agency regarding the emergency measures.