Fracking—hydraulic fracturing—might be the culprit in three Dallas area earthquakes, according to a geophysicist and earthquake expert.
This weekend’s three earthquakes began with the first at 11:05 p.m. Central Daylight Time (CDT) reaching a magnitude of 3.4, according to preliminary U.S. Geological Survey (USGS) data, said Yahoo News/Life’s Little Mysteries. The first quake hit a few miles southeast of the Dallas-Fort Worth International airport; four minutes later, a 3.1-magnitude aftershock hit the area. A third, a 2.1 magnitude earthquake, hit at 10.41 p.m. CDT Sunday; its epicenter was a couple of miles east of the first quake, said the USGS.
Cliff Frohlich, associate director and senior research scientist at the University of Texas at Austin’s Institute for Geophysics said the earthquakes and aftershock appear to be associated with prior wastewater disposal from local fracking operations, wrote Yahoo News/Life’s Little Mysteries. These are the first earthquakes in the area since late 2008 and, said Frolich, the area never previously recorded a magnitude-3 quake. Since, the area has experienced at least one earthquake each year at or about a magnitude 3, except for 2010.
The activity is no coincidence, said Frohlich, who noted that the increased seismic activity in the Dallas area followed the airport being “inundated” with fracking wastewater, according to Yahoo News/Life’s Little Mysteries.
As we’ve explained, fracking employs the use of a drill, fresh water, sand—silica—, and a mix of hundreds of chemicals that are shot through an underground horizontal well until it all reaches a bed of shale rock. In Texas, the formation is the Barnett Shale, in northern Texas. The process releases natural gas. Once fractured, water pressure calms and then internal pressure in the rock creates a so-called “flowback,” in which fracking fluids rise back to the surface, the Environmental Protection Agency (EPA) explained. “That’s dirty water you have to get rid of,” Frohlich told Yahoo News/Life’s Little Mysteries. “One way people do that is to pump it back into the ground.”
In a study Frohlich published in the journal Proceedings of the National Academy of Sciences, he researched 67 earthquakes recorded from November 2009 to September 2011 in a 43.5-mile grid over the Barnett Shale, said Yahoo News/Life’s Little Mysteries. Boyd discovered that 24 of the earthquakes with the most reliably located epicenters had originated within two miles of at least one wastewater disposal injection well.
Oliver Boyd, a USGS seismologist and adjunct professor of geophysics at the University of Memphis, agrees that, for the most part, associates between fracking and seismic activity are possible. “Most, if not all, geophysicists expect induced earthquakes to be more likely from wastewater injection rather than hydrofracking,” Boyd wrote in an email to Life’s Little Mysteries. “This is because the wastewater injection tends to occur at greater depth where earthquakes are more likely to nucleate. I also agree [with Frohlich] that induced earthquakes are likely to persist for some time (months to years) after wastewater injection has ceased.”
We’ve written that, in the last few years, especially, there has been a rise in seismic activity in areas not typically the site of earthquakes. Underground injection wells for disposing fracking wastewater have been used since the 1960s but only recently has more and more fluid been used in the process. This has created a massive amount of wastewater and a need for more disposal sites. Previously, USGS researchers did not theorize why disposing of the wastewater underground is responsible for the earthquakes but other studies suggest the briny, salty nature of the drilling fluid causes lubrication of underground rock. If the site of the underground well is near a natural fault line, the wastewater may eventually cause the rocks to move.