Oklahoma’s earthquakes are threatening a strategic crude oil storage depot, and the state’s regulators are shutting down some disposal wells in response.

That’s the latest in a string of developments as Oklahoma tries to slow down an explosion of earthquakes that seismologists blame on the injection of wastewater from oil exploration.

Reveal reported in February that Oklahoma had three times as many earthquakes as California in 2014.

The earthquakes are not going quietly.

Latest quake count

As of Oct. 19, the state had experienced more than 650 earthquakes of magnitude 3.0 or higher, well ahead of the total for all of 2014, according to U.S. Geological Survey data.

The new threat

A magnitude 4.5 earthquake on Oct. 10 near Cushing, Oklahoma, was the largest in a series of quakes near the Cushing hub, a facility that was storing 54 million barrels of crude oil earlier in October, NPR State Impact’s Joe Wertz reported.

The Oklahoma Corporation Commission, which regulates oil and gas activity, is telling wastewater disposal operators in the area to cut back:

The commission has ordered companies with disposal wells located within three miles of the concentrated quake activity to shut down the wells. Companies with disposal wells located within a three to six-mile radius have been ordered to reduce disposal well volumes by 25 percent.
The commission is telling operators of 13 additional disposal wells – operating in a radius of six to 10 miles from the Cushing quake activity – to prepare for possible cutbacks.

The October earthquake was hardly the first warning sign near the Cushing depot. A peer-reviewed study published in September concluded that faults in the area were capable of producing an earthquake on par with the 2011 magnitude 5.7 earthquake near Prague. Such an earthquake would cause “damage to national strategic infrastructure and local communities,” the study said.

First operator challenges new restrictions

Most companies have complied with a March directive from the corporation commission that put the onus on disposal well operators near earthquakes to either cut back their injection volumes or prove they weren’t injecting into a dangerous layer of rock. Since then, nearly 200 wells have been “plugged back” to get them out of that so-called crystalline basement rock.

However, Marjo Operating Co. Inc. of Tulsa is challenging the regulator’s action. The company’s attorney, Bill Huffman, told The Oklahoman’s Paul Monies that the state should have taken Marjo’s unique operation into consideration:

“We’re just asking them to take a look at our circumstances on an individual level, rather than the blanket action they took,” Huffman said.

A jurisdictional gray area

Marjo isn’t challenging the corporation commission’s actions as a whole, but it might be only a matter of time before someone does.

Not everyone agrees that the corporation commission has the authority to regulate the oil industry when it comes to earthquakes. Even two of the body’s commissioners believe that there’s a jurisdiction question, Mike Soraghan of EnergyWire reported:

“I think we’re headed for a very big lawsuit,” said state Rep. Cory Williams, a Democrat who represents the frequently shaken city of Stillwater. Oil companies might soon challenge regulators’ right to rein in operations, he said, “and they might be right.”

Michael Corey is Reveal's senior data editor. He leads a team of data journalists who seek to distill large datasets into compelling and easily understandable stories using the tools of journalism, statistics and programming. His specialties include mapping, the U.S.-Mexico border, scientific data and working with remote sensing. Corey's work has been honored with an Online Journalism Award, an Emmy Award, a Polk Award, an IRE Medal and other national awards. He previously worked for the Des Moines Register and graduated from Drake University. He is based in Reveal's Emeryville, California, office.