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.
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.
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A lot less people would be nice.
What.the.####
Exaggerate much?
