Fracking’s Latest Scandal? Earthquake Swarms
Turns out that when a barely regulated industry injects highly pressurized wastewater into faults, things can go terribly wrong.
At exactly 10:53 p.m. on Saturday, November 5, 2011, Joe and Mary Reneau were in the bedroom of their whitewashed and brick-trimmed home, a two-story rambler Mary’s dad custom-built 43 years ago. Their property encompasses 440 acres of rolling grasslands in Prague, Oklahoma (population 2,400), located 50 miles east of Oklahoma City. When I arrive at their ranch almost a year later on a bright fall morning, Joe is wearing a short-sleeve shirt and jeans held up by navy blue suspenders, and is wedged into a metal chair on his front stoop sipping black coffee from a heavy mug. His German shepherd, Shotzie, is curled at his feet. Joe greets me with a crushing handshake—he is 200 pounds, silver-haired and 6 feet tall, with thick forearms and meaty hands—and invites me inside. He served in Vietnam, did two tours totaling nine years with the Defense Intelligence Agency, and then, in 1984, retired a lieutenant colonel from the US Army to sell real estate and raise cattle. Today, the livestock are gone and Joe calls himself “semiretired” because “we still cut hay in the summers.”
On that night in November, just as he and Mary were about to slip into bed, there was “a horrendous bang, like an airliner crashing in our backyard,” Joe recalls. Next came 60 seconds of seismic terror. “The dust was flying and we were hanging onto the bed watching the walls go back and forth.” Joe demonstrates by hunching over and gripping the mattress in their bedroom. He points to the bathroom. “The mirror in the vanity exploded as if somebody blew it out with a shotgun.” When the shaking stopped, Joe surveyed the damage. “Every corner of the house was fractured,” he says. The foundation had sunk two inches. But most frightening was what Joe discovered in the living room: “Our 28-foot-tall freestanding chimney had come through the roof.” It had showered jagged debris onto a brown leather sofa positioned in front of their flat-screen TV. Joe shows me the spot. “It’s Mary’s favorite perch. Had she been here…” He chokes up.
The earthquake registered a magnitude 5.7*—the largest ever recorded in Oklahoma—with its epicenter less than two miles from the Reneaus’ house, which took six months to rebuild. It injured two people, destroyed 14 homes, toppled headstones, closed schools, and was felt in 17 states. It was preceded by a 4.7 foreshock the morning prior and followed by a 4.7 aftershock.
The quake baffled seismologists. The only possible culprit was the Wilzetta Fault, a 320-million-year-old rift lurking between Prague and nearby Meeker. “But the Wilzetta was a dead fault that nobody ever worried about,” says Katie Keranen, an assistant professor of geophysics at the University of Oklahoma. We’re driving in her red SUV, just south of the Reneaus’ property, when she stops to point out where the quake tore open a footwide fissure across State Highway 62. The United States Geological Survey (USGS) maintains a database of seismically risky areas. Its assessment of the Wilzetta Fault, Keranen notes, was “zero probability of expected ground motion. This fault is like an extinct volcano. It should never have been active.”
When the Wilzetta mysteriously and violently awakened, Keranen wanted to know why. So she partnered with scientists from the USGS and Columbia University’s Lamont-Doherty Earth Observatory. The morning after the initial foreshock, Keranen’s team scrambled to install three seismometers around Prague. They did so in time to capture the quake system in unprecedented detail. She says, “We got this beautiful image of the fault plane.” Within a week, her team and other scientists had placed a total of 25 devices around the fault zone. One is buried in the Reneaus’ backyard. Now, having completed a yearlong study (just published in the journal Geology), Keranen’s research indicates the Oklahoma earthquakes were likely attributable to underground injection of wastewater derived from “dewatering,” separating crude oil from the soupy brine reaped through a drilling technique that allows previously inaccessible oil to be pumped up. “Pretty much everybody who looks at our data accepts that these events were likely caused by injection,” Keranen concludes.
“We still feel tremors weekly,” complains Joe Reneau. “They rattle our windows.” The couple hasn’t bothered to rehang family photos in their living room. Instead, the framed snapshots are stacked in tidy piles on a coffee table.
Such seismic activity isn’t normal here. Between 1972 and 2008, the USGS recorded just a few earthquakes a year in Oklahoma. In 2008, there were more than a dozen; nearly 50 occurred in 2009. In 2010, the number exploded to more than 1,000. These so-called “earthquake swarms” are occurring in other places where the ground is not supposed to move. There have been abrupt upticks in both the size and frequency of quakes in Arkansas, Colorado, Ohio, and Texas. Scientists investigating these anomalies are coming to the same conclusion: The quakes are linked to injection wells. Into most of them goes wastewater from hydraulic fracking, while some, as those in Prague, are filled with leftover fluid from dewatering operations.
The impact of fossil fuels is no secret, but until now the short list of dirty energy’s villains never included water. Together, oil and gas extraction and production generate about 878 billion gallons of wastewater annually, roughly what tumbles over Niagara Falls every two weeks. More than a third is injected back into disposal wells. With natural gas production on the rise—it has jumped 26 percent since 2007, chiefly because fracking now makes it economically viable to pursue gas trapped in shale deposits—and unconventional practices such as dewatering ramping up domestic oil development, the wastewater deluge is expected to get worse. Operators are injecting more water than ever into drilling wells, while boring new wells to accommodate the overflow. Yet nobody really knows how all this water will impact faults, or just how big an earthquake it could spawn. In the West, small quakes don’t often cause much damage because of stricter seismic regulations but also because the underground formations—buckled, with younger rock—absorb all but the biggest events. Induced quakes, however, are happening primarily in flatter states, amid more rigid rock, making them more destructive—a stone makes a bigger splash when it’s hurled into a glassy pond than a river of raging whitewater.
- Fracking’s Latest Scandal? Earthquake Swarms (motherjones.com)
- New Study Confirms Water Injection Caused Oklahoma Earthquake (planetsave.com)
- Oklahoma Quake Tied to Wastewater Shows Oil Boom Impact (bloomberg.com)
- Oklahoma is at the Epicenter of a Debate About Industry and Earthquakes (stateimpact.npr.org)
- Largest Oklahoma Earthquake Linked to Oil Extraction Wastewater (livescience.com)
- Oklahoma Earthquake Was Largest Linked to Injection Wells, New Study Suggests (stateimpact.npr.org)
- Wastewater injection spurred biggest earthquake yet, study finds (prn.fm)
- Wastewater injection spurred biggest earthquake yet, says study (oddonion.com)
- Giant Oklahoma Earthquake Might Have Been Our Own Fault (geekosystem.com)
- Oil Addiction, Not Fracking, Caused the 2011 Oklahoma Earthquakes (blogs.scientificamerican.com)