Oklahoma for long has been known as the "Sooner State," a reference to early settlers who sneaked into the then-territory in 1862 ahead of a deadline for claiming land. But pretty soon, thanks to waste water generated by hydraulic fracturing for oil and gas, it may be calling itself the Earthquake State.
Last week, in an appearance at the Enid Rotary Club, a government official said that the state has become the top place on the planet for earthquakes, when it comes to frequency.
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"We have had 15 (earthquakes) in Medford since 5 o'clock Saturday morning," said Matt Skinner, a spokesman for the Oklahoma Corporation Commission., which regulates the oil and gas industry. "We've got an earthquake issue."
"Oklahoma is absolutely unique in terms of the number of earthquakes we've had," he said.
According to the Center for Investigative Reporting, which analyzed data from the U.S. Geological Survey, Oklahoma had three times as many quakes last year as California, with 562 events of magnitude 3.0 or greater.
There's growing evidence of the link between earthquakes and the disposal of waste water created in the fracking process by injecting it deep underground. A study by Stanford University researchers, published in June in the journal Science Advances, found that the rising seismic activity coincided with disposal of waste water into the Arbuckle formation, a 7,000-foot-deep sedimentary formation beneath the state.
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Fracking accesses difficult-to-reach oil and gas deposits by pumping a combination of sand, gas and chemicals into the Earth to crack through rock. Though the process uses large amounts of water, it's not that H2O that actually causes the quakes, the researchers found. Instead, the culprit seems to be "produced water" - a brackish fluid that's naturally present with oil and gas deposits in the Earth. When oil and gas are extracted, drillers separate produced water from them, so that it can be re-injected into even deeper disposal wells.
What we've learned in this study is that the fluid injection responsible for most of the recent quakes in Oklahoma is due to production and subsequent injection of massive amounts of waste water, and is unrelated to hydraulic fracturing," said Mark Zoback, a professor in Stanford's School of Earth, Energy and Environmental Sciences.
As Rivka Galchen noted in an April New Yorker article, earthquakes have become so common in Oklahoma that local TV weathermen often report the day's seismic events along with the temperature.