LINDA WERTHEIMER, HOST:
Until very recently, earthquakes in Oklahoma were unheard of. But this year, the state has seen more tremors than California. Why is that? It's a subject of debate. Some scientists point to the way the oil and gas industry disposes of wastewater, a byproduct of drilling and of the process called fracking. Earlier this month, a study published in the journal Science found what it called a clear link between wastewater wells and earthquakes. But many gas companies and state regulators disagree. They claim it's too soon to say. We turn to energy reporter Joe Wertz of StateImpact Oklahoma for an update on the controversy. Joe, welcome to the program.
JOE WERTZ: Thanks for having me.
WERTHEIMER: Before we get to the study, could we have just a little bit of background here, Joe? What are these disposal wells that we're talking about?
WERTZ: Well, when you drill for oil and gas, you get a lot of wastewater. When the oil and gas comes to the service, it brings a lot of wastewater with it. And oil and gas companies need to pump that wastewater thousands of feet underground to lock it under layers of rock to keep it away from the water table. Oklahoma has more than 10,000 of these disposal wells.
WERTHEIMER: OK. Then let's get back to the study, which was done by Katie Keranen. She's a research seismologist at Cornell University. She looked at an area experiencing a lot of quakes very near where you are, Joe - the town of Jones, a small town just northeast of Oklahoma City. Tell us what she found.
WERTZ: Well, more than 2,500 earthquakes have shaken this area since 2008, which accounts for about 20 percent of the quakes in the middle of the United States. Most of these disposal wells don't cause quakes, but the earthquakes near Jones could have been caused by a handful of high-volume wells, where millions of barrels of water are pumped every month. What Keranen found is twofold. First, she found that wastewater pumped into the ground can travel a lot farther than initially thought and that it builds up pressure all along the way on its path. And this pressure can cause fault lines to slip and trigger an earthquake.
WERTHEIMER: Does anybody regulate these wells?
WERTZ: There's a little regulation when it comes to earthquakes. In Oklahoma, oil and gas officials have stiffened monitoring requirements for certain disposal well operators.
WERTHEIMER: So presumably, if there's an earthquake, they will notice that it happened.
WERTZ: Right. And they hope that the extra data that they'll get from this monitoring will help them identify the warning signs to prevent them in the future. They also have a process to evaluate the risks and shut down a well if they think it's causing quakes. And they're no longer rubberstamping disposal well permits in earthquake-prone areas. Other states, however, have been more aggressive with regulation. It's important to remember, though, that most of Oklahoma's quakes are small. And these disposal wells are a key part of the oil and gas industry, and you really can't drill without them.
WERTHEIMER: And Oklahoma lives and dies by oil and gas.
WERTZ: They sure do. And it's - Oklahomans are generally very accepting of the oil and gas industry. And it's a low-regulation state. They're very tolerant of this stuff, so we're kind of in a weird area. There's a lot of people, you know, who are impacted by the earthquakes that also work in the oil and gas industry. So we're put in a precarious situation between this phenomenon that's happening and an industry that we'd like to preserve and promote.
WERTHEIMER: Joe Wertz is an energy reporter for StateImpact Oklahoma. Joe, thank you very much for joining us.
WERTZ: Thank you for having me. Transcript provided by NPR, Copyright NPR.