A 5.6 magnitude earthquake shook Pawnee, Oklahoma over the weekend, and it’s strongly suspected that oil and gas drilling is to blame. Seismic activity has spiked significantly in the state over the past few years, and scientists have linked the increase of these small-magnitude tremors with the storage of drilling projects’ wastewater underground. Just a few weeks ago, the U.S. EPA acknowledged this link, and though the USGS said in a statement that it “cannot currently conclude whether or not this particular earthquake was caused by industrial-related, human activities,” there’s not a great deal of doubt left that this was drilling-related.
Our best understanding of what’s happening goes something like this: the wastewater left over after hydraulic fracturing operations is often disposed of in old, depleted wells, but in so doing exerts pressure on underground faults that can lead to tectonic “slipping.” So while it’s a byproduct of fracking and not the actual drilling that’s being tied to these earthquakes, this is still shaping up to be perhaps the biggest challenge the industry currently faces.
And Oklahoma is taking it seriously. Back in March, the state’s Corporation Commission moved to decrease the underground storage of drilling wastewater by 40 percent. In the wake of that decision, seismic activity has dropped 20 percent, and as the New York Times reports, the commission quickly moved to stop wastewater injections in wells close to Saturday’s earthquake:
The Oklahoma Corporation Commission, which oversees oil and gas activity, announced that it had ordered the shutdown of wastewater wells across about 500 square miles in the area hit by the quake. About three dozen wells are affected, and will have to shut down in as little as a week, [Governor Mary Fallin] said on Twitter.
The vast majority of seismic activity occurring in Oklahoma recently has been relatively small in magnitude, but the Pawnee quake underscores the weight of the problem. For its part, the industry is already working on measures to get around the wastewater storage problem, experimenting with frackwater alternatives like polyallymaline fluid and propane gel, as well as efforts to recycle wastewater. Given the blistering pace at which the shale industry has innovated over the past decade, there’s reason to believe these companies may be up to the challenge. But if not, it’s good to see that Oklahoman regulators are ready and willing to step in when needed.