Railroad Commission's Explanation of Irving Quakes: ¯\_(?)_/¯
An EarthquakeTrack.com representation of USGS earthquake data.
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Calling Irving's Thursday City Council meeting a wasted effort wouldn't be right. The council did award the landscaping contract for O'Connor Boulevard, after all. And on the other big issue concerning Irving -- earthquakes -- the SMU seismologists on hand did what little they could, too. They told the assembled council and crowd that yes, their city has been struck by an "earthquake swarm." Yes, there have been more than 120 earthquakes in North Texas since 2008 and no, there were none recorded before then. Locals may have felt some seismic activity once, in 1950, Brian Stump and Heather DeShon said, but that was only a possible quake. Either way, there have bunches more earthquakes here in the last six-plus years than ever before, as far as anyone knows.
Irving is the fourth area of North Texas to be swarmed by earthquakes in the last six years. In 2008 and 2009 there was a quake outbreak near DFW airport; around the same time, tremors hit Cleburn. Those quakes dissipated the next year. Azle suffered its swarm beginning in the fall of 2013 and continued into 2014. In each previous swarm, Stump emphasized, the quakes became smaller and less frequent after the swarm's biggest quake. (Well, yeah, anything not the biggest in its group is necessarily smaller. It would be nice to know exactly how big the biggest quake might be and when it might arrive, but science isn't quite there yet -- not by a long shot.)
As they did on January 6, the date of Irving's 3.5 and 3.6 magnitude tremors, Stump and DeShon said that it was plausible or possible that the earthquakes were caused by the drilling industry's practice of disposing of wastewater created during the hydraulic fracturing process by pumping it deep underground in injection wells. But the duo couldn't begin to pinpoint the cause, they said, until they are able to study data from the 22 seismometors they and their team have installed in Irving. Once they figure out the exact locations of the quakes' epicenters -- Stump said the epicenters the U.S. Geological survey have reported could be off by as much as three to six miles -- they can begin to look at what is causing them.
Then it was Craig Pearson's turn. Pearson is the Texas Railroad Commission's in-house seismologist, hired by the agency after it became fearful that the fracking wells it was signing off on might be causing earthquakes. Pearson, as he did in an column published Wednesday by The Dallas Morning News, expressed doubt that fracking could be responsible for the Irving earthquakes. He trotted out the same information he's trotted out time and again, that there are no wells, be they fracking or disposal, currently operating in Irving or Dallas County. Pearson did not tell the crowd that studies have shown the pressure differences created by wells can last years after the wells go out of service. Pearson did not offer an alternative theory for the quakes' cause.
Despite the small likelihood of bigger earthquakes hitting the region, Stump and Dallas County Judge Clay Jenkins, who made a cameo at the meeting, emphasized the need for Irving and Dallas County residents to exercise caution. Jenkins mentioned that residents might want to rehang wall adornments to make sure the nails securing them were firmly in place, saving the evening's earthquake conversation from being completely pointless.
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