Hydraulic fracturing, the natural gas drilling technique that involves pumping fracking fluid at high pressure into the earth to release gas deposits locked in underground rock formations, has long raised concerns about air and water pollution. But now, another potential fracking hazard is gaining notice – earthquakes that may occur when salt water, a byproduct of fracking, is injected into the ground.
Injecting the salt water produced by fracking is a common method of disposal among natural gas drillers. But according to a Fox News report, experts say the salt water can lubricate the rock surrounding it, possibly leading to earthquakes.
That’s what some suspect may be happening in Arkansas, which has experienced a sudden surge in seismic activity, including the biggest earthquake recorded by the state in more than three decades. According to Fox News, 90 percent of the earthquakes recorded in the state since 2009 have occurred within six kilometers of salt water disposal sites associated with fracking operations. Steve Horton, an earthquake specialist at the University of Memphis and hydrologic technician with the U.S. Geological Survey, told Fox the coincidence is too big to ignore.
There is no scientific consensus on this idea, and earthquake activity had occurred in Arkansas prior to the recent fracking boom. But one seismologist consulted by Fox said there could be two kinds of seismic activity in the area — one natural, the other caused by pumping salt water into the ground.
We’ve reported on this phenomenon before. Last year, we wrote that fracking had been named a suspect in a series of minor earthquakes that occurred in West Virginiaâ€™s Braxton County. Last April, Braxton County experienced a 3.4 magnitude earthquake. Between April and the end of August the area was the site of at least six more, according to West Virginia Public Broadcasting. Most were around a 2.7 magnitude â€“ not enough to cause damage but enough for people to feel them.
A town in Braxton County called Frametown is home to holding tanks that store water used in hydraulic fracturing, or fracking, operations. The West Virginia Department of Environmental Protection has permitted Chesapeake Energy to use a nearby underground well to dispose of the drilling fluid. About ten million gallons of drilling fluid had been pumped into the well since the spring of 2009. At the time we reported on the West Virginia earthquakes, the state and Chesapeake were trying to determine if the drilling fluid injections were related to the seismic activity.
In 2009, the disposal of fracking wastewater was also named a possible suspect in a series of earthquakes that plagued North Texas, in the Dallas-Fort Worth area. According to a Wall Street Journal report filed at the time, Chesapeake Energy shut down two disposal wells in the area “as a precautionary measure” due to the upswing in seismic activity.
Researchers from Southern Methodist University in Dallas who deployed sensors to study the seismic activity said their research did show a “possible correlation” between the activity and one of Chesapeake’s disposal wells, the Journal said. The disposal well in question was located at Dallas-Fort Worth Airport, which sits atop a fault line.