Two lawsuits in Oklahoma accuse more than a dozen oil and gas companies of triggering recent earthquakes by disposing of their drilling waste in deep wells.

The lawsuits filed last week come on the heels of heightened earthquake activity in Oklahoma, where more than 130 this month have registered magnitude 2.5 or higher on the Richter Scale. These events have caused property damage, knocked out the local power supply, and shaken people’s faith in the state government’s ability to control the situation.

“It’s pretty intense right now,” said Jeremy Boak, a geologist at the Oklahoma Geological Survey. He explained that the state has already experienced seven earthquakes of at least magnitude 4.0 in the past three weeks—about one-quarter the total of such quakes in 2015.

Responding to the growing concern about risk to people and property—and the possibility of an even bigger earthquake on the way—both Republican and Democratic state representatives recently held public forums and said new legislation is needed on this issue.

Energy regulators at the Oklahoma Corporation Commission (OCC) told InsideClimate News that they share the public’s concern.

“Many of us are among the concerned citizens, as we live in earthquake areas and have seen and felt first hand what’s happening to our homes,” OCC spokesman Matt Skinner wrote in an email.

Perhaps the biggest indication of public frustration and anxiety, however, is the growing number of lawsuits. Four have been filed on the issue in Oklahoma, all targeting energy companies. None of the cases have yet reached the hearing stage.

Lawyers say another lawsuit will be filed by the end of the month, on behalf of the Sierra Club. It accuses four energy companies of violating the federal waste management rule called the Resource and Recovery Act, said Scott Poynter, a lawyer involved in that case and two of the state lawsuits.

“The longer the [oil and gas] industry is out there causing the harm, the more likelihood there is going to be litigation because it is the only way people can get a remedy for problems that the industry is causing,” said Deborah Goldberg, an environmental lawyer for the environmental group EarthJustice. The organization is not involved in the cases.

Holiday Jolts Spur Action

Fourteen residents from Edmond and Oklahoma City filed a lawsuit on Jan. 11 in Oklahoma County, alleging that the drilling wastewater activities of a dozen oil and gas companies caused two damaging earthquakes that recently rattled the area.

In the early morning of Dec. 29, a magnitude 4.3 earthquake struck—one of the largest observed in the area; three days later, also in the morning, a magnitude 4.2 quake struck. Regulators responded by ordering companies within 10 miles of the earthquake’s epicenter to reduce their well disposal activity—in some cases by as much as 50 percent—and issued directives for extra well testing for operators farther away.

According to the lawsuit, the defendants knew that waste injection could trigger earthquakes and decided to do it anyway “with reckless indifference and callous disregard for the potential harm to Plaintiffs and others.”

The plaintiffs are accusing the companies of negligence and seeking compensation from quake-related damages such as “destruction and loss of personal property, cracked and broken interior and exterior walls, bricks and fascia, and movement of the foundations beneath their dwellings.”

The suit does not specify damages sought.

The lawsuit targets most of the companies named in the recent regulatory response effort, along with an additional company, Northport Production Co. (One company named in the regulatory action plan is possibly out of business and was not named in the suit.) The remaining defendants are a mix of Oklahoma- and Texas-based energy companies, including Devon Energy Corporation; Sundance Energy Oklahoma LLC; Grayhorse Energy LLC; Pedestal Oil Co. Inc.; New Dominion, LLC; R.C. Taylor Co. Inc.; Tnt Operating Inc.; White Operating Co.; Rainbo Service Co.; Marjo Operating Company; and Special Energy Corporation.

New Dominion did not respond to comment by deadline. Pedestal Oil Co. declined to comment.

Another lawsuit was filed in Logan County, with two residents, Lisa Griggs from Logan County and April Marler from Oklahoma County, seeking compensation for earthquake-related property damage. This one is a class action lawsuit, open to anyone who has owned property in the state since 2011 to join.

The 27-page lawsuit cites scientific studies that connect the recent dramatic spike in earthquakes to the time when oil and gas exploration, and the industry’s waste production, increased. The rise in energy production is tied to the use of hydraulic fracturing, or fracking, a method to extract fossil fuels that were previously hard to access.

Oklahoma’s oil production nearly doubled, and natural gas production jumped between 2009 and 2014. Earthquakes also increased in that time, from 50 in 2009 to about 5,400 in 2014. Regulators and scientists agree the increased levels of wastewater injection are likely triggering the quakes.

The plaintiffs say the more than a thousand quakes over the last five years are caused by the disposal of oil and gas waste.

The four companies targeted in this lawsuit—Chesapeake Operating, LLC; New Dominion, LLC; Devon Energy Corporation; and SandRidge Exploration and Production—were responsible for more than 60 percent of disposal activity in 2014 in the state’s epicenter of waste disposal, the Arbuckle formation, Poynter said.

The big question is whether the plaintiffs can prove that the damage was due to activities of the specified oil and gas companies, explained Blake Watson, a law professor from the University of Dayton. Even if they can prove this, he said, they will also have to prove the companies were negligent.

Both lawsuits argue that oil and gas waste disposal should be labeled an “ultrahazardous activity.” This means that if the earthquakes in question are tied to waste disposal, the companies would be liable for damages even if the companies were not guilty of being negligent or acting improperly, explained Watson.

The lawsuit focusing on the Dec. 29 and Jan. 1 events also seeks to permanently shut down the disposal wells in question.