Texas, a state that has, historically, been light on seismic activity, has recently endured a considerable number of earthquakes, which, while not damaging, have come as a troubling surprise. Seismologists have concluded that wastewater disposal wells from fracking are causing the unpleasant phenomenon, adding new cause for concern regarding a natural gas extraction process that is already steeped in controversy.
The earthquakes, which increased in frequency and intensity from 2001 onward, happen to be near areas with dozens of deep injection wells, which are used for disposing of wastewater from fracking, a problematic natural gas extraction process.
"There is definitely a credible link between wastewater disposal, primarily related to the production of gas from the Barnett Shale, with earthquakes, said geophysicist Bill Ellsworth. "At this point the earthquakes are a bit of an annoyance, certainly, and there's always the possibility that something larger might occur."
The Barnett Shale is prized by fracking advocates and the gas/oil industry, as it has the largest reserves of any onshore natural gas field in the U.S.
The number of earthquakes occurring in the midcontinent region during 2011 totals 134 - that's a 47-quake jump from the year before. "We find there is a statistically significant increase in the rate [of earthquakes] just over the past several years. And many of those are in areas where we know there is a lot of energy activity."
Even though the tremors occurring throughout the area are small, experts suggest the matter is not to be taken lightly.
"A naturally occurring rate change of this magnitude is unprecedented outside of volcanic settings or in the absence of a main shock, of which there was neither in this region," read a study on the matter, which was partially authored by Ellsworth.
The National Academy of Sciences added, "A string of seismic events in Arkansas, Ohio, Oklahoma, and Texas in the past several years has been related to wastewater disposal associated with oil and gas production. These events were felt by local residents, and have brought the issue of human-caused seismicity firmly into public view."
And according to geologist Murray Hitzman, of the Colorado School of Mines, as fracking is continuously pursued, the issue will certainly not go away. "We're going to cause more events as we drill more wells," he warned. "I think there's not much question about that. But we understand what's happening pretty well and I think we can get in place, without too much problem, protocols and systems so that we can deal with this in a reasonable way."
The idea that pumping wastewater into the ground can have disastrous consequences is also nothing new, said Dr. Cliff Frohlich, Associate Director of and Senior Research Scientist at the University of Geophysics, at the University of Texas in Austin. "In the scientific community," he explained, "it was pretty much established in the 1960s that injecting fluids into the ground sometimes causes earthquakes."
Such earthquakes are triggered when the fluids from an injection relieve friction on a nearby fault. All the disposal wells near where the quakes are happening typically report rates of injection exceeding 150,000 barrels of water per month - more than enough to shake things up.
The quakes "are occurring more frequently now because there's so much more fluid injection," said Frohlich, "due to fracking and the development of unconventional gas. This gas boom is huge."
And such a huge "boom" means that Texas is not the only area subject to unnaturally-caused tremors. Earthquakes in Youngstown, Ohio are also understood to be the product of unsafe fracking and wastewater disposal.
But boom or no boom, much of the problem can be linked to the profit-driven greed of the gas industry itself. "If [the] disposal is causing earthquakes," said Frohlich, "you can find a different way to dispose of it. You can dispose of the stuff in a different well, or you can take it to a fluid treatment plant. But the people involved in this are going to do the cheapest way of doing things."
Photo: A Stephen F. Austin State University professor notes the ground shift between two earthquakes recorded in Timpson, Texas in May. The recent uptick in seismic activity has been linked with fracking wastewater disposal wells. Andrew D. Brosig/AP & The Daily Sentinel