Fracking Seems to Be Causing Hundreds of Earthquakes Across the Country Each Year

The New Year is off to a shaky start on the southern Great Plains. A spate of small earthquakes rattled the fracking belt of Texas and Oklahoma over the past week and evidence is mounting that the tremors may be connected to fracking.

On Wednesday alone, the US Geological Survey reported two quakes in north-central Oklahoma, a magnitude 3.0 near the Kansas state line and another magnitude 3.8 south of Guthrie, which lies on the outskirts of Oklahoma City. And a swarm of small quakes hit Tuesday and Wednesday around Irving, Texas, the Dallas suburb that's home to the headquarters of oil and gas giant ExxonMobil, a pioneer of America's fracking boom.

"People all over an area extending at least 40 miles away in every direction are noticing it, reporting, and talking about it," Dallas fracking opponent Marc McCord told VICE News.

Scientists have known for decades that pumping fluids into the ground has the potential to cause earthquakes.But the boom in the use of fracking technology to tap into rock formations deep underground has led to "great volumes" of chemical-laden drilling wastewater being pumped back into the Earth, USGS geophysicist William Ellsworth told VICE News.

It's not the fracking itself, but the water that's being pumped out and re-injected underground that's the issue, he said. That puts pressure on layers of rock far below the surface, which can trigger a tremor even in areas where there's little history of quakes, he said.

"Most of the earthquakes are small. They're certainly an annoyance for people who aren't used to experiencing earthquakes," Ellsworth said. "When your house shakes, it's an unnerving feeling, certainly, and some of them have done some damage."

The USGS recorded several moderate quakes in "areas relatively new to seismicity" in 2014, the agency reported this week. Those areas included Oklahoma and Kansas — prairie states with little history of tremors. Oklahomans experienced 564 quakes of a magnitude 3 or higher in 2014, up fivefold from 2013, a recent analysis by Environment and Energy News found — making a state with no major faults the most seismically active state in the continental United States.

Deep underground, "The stresses are high even in the stable parts of the continental interior," Ellsworth told VICE News. "As fluids are injected underground, they will be raising the pressure even at great distances from the injection point."

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Scientists are studying similar seismic activity in Ohio, where scientists linked a swarm of 77 small earthquakes outside Youngstown in early 2014 to a drilling operation. And, regulators in British Columbia tied dozens of quakes — one as large as a magnitude 4.2 — to drilling activity.

Ellsworth told VICE News that concerns over earthquakes have led communities in Arkansas, Ohio, and Colorado to force drillers to abandon wells. But the main concern for regulators is groundwater, not quakes, he said.

And there's little drilling going on in the area of metro Dallas where the quakes have been occurring. They're clustered tightly around the site of the now-demolished Texas Stadium, the former home of the NFL's Dallas Cowboys, and there are no injection wells anywhere nearby, said McCord, director of the anti-fracking group FracDallas. It's primarily an industrial area nearby where two faults, the Ouachita Tectonic Front and the Balcones Fault Zone, converge along the Trinity River.

"There are only two gas wells that were drilled in that area," McCord told VICE News. One of the wells was shut in almost as soon as it was completed several years ago, and the other was closed off after a blowout deep underground, he said.

"Never, ever before they started fracking had I felt an earthquake in the Dallas area," said McCord, a Dallas native. He suspects they may be related to the wells that were drilled more than five years ago — but trying to nail down the cause "takes a lot of money and a lot of time, and nobody's spending the time and money to do it."

"Is it related? Who knows?" he asked. "But what else could you possibly look at to say it's a probable cause?"

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The Texas Railroad Commission, which regulates oil and gas drilling in the state, is working with scientists at Southern Methodist University to figure out the cause, spokeswoman Ramona Nye told VICE News. It's also checking into whether the two wells — one of them that never produced natural gas, the other shut down since 2012 — are properly contained, she said.

But in a statement released by the agency, Railroad Commission seismologist Craig Pearson said: "There are no oil and gas disposal wells in Dallas County. And I see no linkage between oil and gas activity and these recent earthquakes in Irving. Earthquakes can be caused by numerous factors and all possible causes need to be examined, including natural causes."

Meanwhile, Dallas County Judge Clay Jenkins, the county's top elected official, told residents to brush up on public safety: "While the cause of these earthquakes is still being investigated and the threat for a major earthquake in Dallas County remains low, I would encourage our residents to review important earthquake preparedness and safety information from FEMA and the American Red Cross."

Follow Matt Smith on Twitter: @mattsmithatl