Oklahoma has become one of the world’s most notorious earthquake hubs. In fact, in 2014 for the first time, the number of magnitude 3 or greater quakes in the state surpassed California’s total.

In terms of natural disasters, the place “where the wind comes sweeping down the plain” has historically been better known for tornados. That’s changing. The increased seismicity is a relatively new phenomenon, simultaneous with the uptick in oil and natural gas activities in the state over the last decade. Though Oklahoma typically experienced zero to a couple magnitude 3 or greater quakes annually, the rate shot up to 20 in 2009. In 2013, the state had 109 such earthquakes followed by 579 in 2014, 903 in 2015, and 623 in 2016. In other words, the state went from some two sizable quakes a year to two or three a day.

Hydraulic fracturing, or fracking, has been a lightning rod for the blame, but it’s not so much the fracking itself as the cleanup afterwards that’s inducing these temblors. Fracking involves shooting a high-pressure stream of water, sand, and chemicals into the ground to release gas from shale. But in the process, hazardous fracking fluid and toxically salty water rise to the surface as well, so to dispose of this dangerous waste, companies pump it down a different opening deeper under the shale to rest permanently in a well of porous rock.

The thing is, when these wastewater injection wells are continuously filled, pressure builds up on geologic faults—enough to cause earthquakes when the two sides of a fault slip past each other, the U.S. Geological Survey acknowledges. In 2009, companies in Oklahoma pumped 849 million barrels of wastewater into wells. By 2014, that number hit 1.5 billion.

That’s been a problem for Oklahoma’s Pawnee Nation and their advocate Erin Brockovich, the famed environmental activist lawyer, given that the tribe has endured some of the most devastating earthquakes in the state. On September 3, 2016, a magnitude 5.8 quake hit right near the town of Pawnee—Oklahoma had never experienced one more powerful—and was felt from Texas to South Dakota. Then on November 6, 2016, a 5.0 earthquake hit nearby Cushing. Exacerbating the danger, Cushing is the storage site of 60 million barrels of oil, the largest supply of crude in the world—a sticking point of concern for the Department of Homeland Security.

The Pawnee Nation has retained the services of law firm Weitz & Luxenberg, aided by Brockovich, to sue Eagle Road Oil LLC, Cummings Oil Company, and 25 other oil and gas companies for damage to its historic governmental buildings and reservation property resulting from what it alleges are human-induced quakes. The tribe’s petition suggests the defendants were “knowingly causing” the quakes and that their actions “constitute wanton or reckless disregard for public or private safety.”

Earthquakes 101

At the damaged main communal building, a former school house built in 1878, white teachers used to teach skewed versions of Native American history to Pawnee students. Now oil companies are trying to school the Pawnee tribe in what they say is really going on with the seismicity, deflecting blame from the salt-water deposit wells. Eagle Road and Cummings did not respond to a request for comment for this article. (Learn more about the earthquake spike.)

Heading to Tribal Court

Even though he was raised in San Diego and is no stranger to earthquakes, Andrew Knife Chief, executive director of the Pawnee nation, recalled the particular shock of the 5.8 magnitude quake.

“That was the one earthquake that started out with a bang but then rumbled and rolled,” he told me. “It was the one earthquake where I go, ‘Oh, this is a big deal. This is a big one.’ You could feel it. It kept going and going. It shook the ground for about a minute.” The tribe has had to deal with the ensuing emotional fallout among it members and physical damage to its buildings.

Though the Oklahoma Corporation Commission, the state’s oil and gas regulator, has ordered reductions on water disposal in certain areas, the risks of earthquakes are still pervasive. To boot, Environmental Protection Agency Administrator Scott Pruitt was a long-time Oklahoma politician who championed the oil and gas industry, a fact that leaves Brockovich and others skittish about what protections will remain in place to prevent earthquakes. And though it has found its reservation land shaking, the Pawnee Nation is bringing the arbitration against oil companies to its home turf: the tribal court.

“The Nation wanted this to be an assertion of their sovereignty,” said Curt Marshall, counsel for Weitz & Luxenberg representing the Pawnee. “After all, they are a nation, a sovereign nation: they have jurisdiction, even over non-Indians, on their land.” When non-Native American entities lease property on reservation land, as the oil companies have done, they agree to the jurisdiction of the tribal court, which often has a lighter docket and can more swiftly process cases.

Brockovich visited a Pawnee town hall earlier this year and was back in the state at Oklahoma State University earlier this month with Bob Bowcock, an associate and water treatment engineer, to hold a colloquium about earthquakes and the plight of the Pawnee. She’s taken a passionate stand in this conflict given her fondness for Oklahoma, where she spent her childhood summers in Ponca City with her grandparents.

“The only thing I’d worry about growing up there was tornadoes,” Brockovich said. “Now I’d be afraid not of a tornado, but an earthquake? That’s just bizarre.”

It’s difficult, she says, “to go back to Oklahoma, to see how on edge [the Pawnee people] are. The question they keep asking is, ‘When will it end?’”

The case will likely be a battle of experts in structural engineering on the cause of the damage, and liability on the part of the oil and gas companies remains up for debate.

“I suspect it will also be a matter of whether, in the absence of a formal Oklahoma Geological Survey position that seismicity was induced until early 2015, and with company compliance with directives of the Oklahoma Corporation Commission afterwards, the companies were on the right side of the law or not,” said Jeremy Boak, director of the Oklahoma Geological Survey.

Kim Hatfield, chairman of the Oklahoma Independent Petroleum Association's (OIPA) induced seismicity working group, recognizes the need for preparedness near the Pawnee reservation and in Cushing even as he allays fears.

“The design of the facilities at Cushing is robust,” he said. “Having said that, since Oklahoma is a seismically active province, it is still prudent to plan for significant seismic events, whether they are natural or induced.”

Yet the Trump administration and the EPA’s Pruitt are looking to loosen the leash on energy regulation.

“My take on Mr. Pruitt is that he feels that the states have been the subject of regulatory overreach by the federal government,” OIPA’s Hatfield said. “To the extent that the EPA is made to abide by their own procedures instead of unilaterally forcing regulation under duress, it will be a significant departure from past practices.”

Still, the concerns in Cushing aren’t just about the oil storage. There are massive amounts of fluids and gases that are pushed through pipelines in Cushing, and much of that infrastructure is aged—and just 20 miles from Pawnee.

Boak acknowledges the continued risk for major seismic events in the region but says there is scant data to predict them.

Protecting Water

The Pawnee tribe says it doesn’t want to curb business in the state.

“We are not anti-oil and gas,” Knife Chief said. “We are not anti-using our land’s resources. What we are trying to push back against is the irresponsible production of oil and gas and the irresponsible disposal of waste water.”

The lawsuit may be about property damage resulting from the deep-water injection following fracking, but that’s more of a litigious foothold to fight against something greater.

“If an earthquake comes through here and destroys the buildings, we can rebuild,” Knife Chief said. “But if you pollute our water, we’re done. And we have warning sides and indications that our water ways are becoming more polluted.”

Brockovich’s father worked for the oil industry as a mechanical engineer who ran the pipelines, she said, “and yet he’s the one who taught me the value of water, what we are capable of doing to it, and how important that is in our health.”