A 5.6-magnitude earthquake struck early Saturday near the town of Pawnee, Oklahoma, close to key oil-storage facilities, leading state regulators to order about 35 fracking waste-disposal wells in the area to be shut down.
The Oklahoma Corporation Commission, which regulates the oil industry in the state, is contacting the operators of the wells in a 500-square-mile area around Pawnee, Governor Mary Fallin said in a Twitter post. The complex of oil storage and pipeline facilities at Cushing, Oklahoma, just 25 miles from Pawnee, was undamaged, according to the commission.
The quake hit the area about 7:02 a.m. Oklahoma time, the U.S. Geological Survey said in a statement, adding that it was the largest in the state since 2011. The surrounding region of Oklahoma and Kansas -- a center of oil exploration using hydraulic fracturing, or fracking, technology -- has seen close to 80 other magnitude-4 quakes or larger events over the past decade.
The surge in earthquake frequencies has been tied to waste water disposal wells used in oil and natural gas drilling operations. Last week, the crude storage levels at Cushing stood at nearly 64 million barrels, according to the Energy Information Administration data.
Officials for Enterprise Products Partners LP, Kinder Morgan Inc., Magellan Midstream Partners LP and Enbridge Inc., which operate petroleum terminals, pipelines and storage facilities in Cushing, said their sites sustained no damage and that operations were normal.
“Following the earthquake, Enbridge employees were directed to conduct visual inspections of tanks, manifolds and other facilities,” spokeswoman Jennifer Smith said in an e-mail. “The Cushing terminal is currently operating normally."
A spokesman for the Oklahoma Corporation Commission, Matt Skinner, offered similar comments.