Geologists say fracking wastewater disposal wells in central Arkansas caused an outbreak of thousands of minor earthquakes.
The Arkansas Oil and Gas Commission placed a ban on fracking wastewater wells in the area yesterday. A moratorium on well activity had been in place for months as geologists investigated a possible link between fracking activity and the outbreak of more than 1,200 earthquakes that measured lower than 4.7 in magnitude.
Fracking is a common term for hydraulic fracturing, a controversial gas drilling method that involves pumping water and chemicals deep underground to break up rock and free natural gas.
Fracking produces millions of gallons of wastewater, and the gas industry has been experimenting with different ways to dispose of it.
At least three gas companies were injecting fracking wastewater in the area of the earthquake outbreak, including BHP Billiton Petroleum, Clarita Operating LLC and Chesapeake Operating. The companies were injecting fracking wastewater near an active fault.
Steve Horton, an earthquake expert from the University of Memphis, told Truthout that continued fracking activity near the fault could have caused an earthquake strong enough to cause property damage.
At least one resident in the area is suing the gas companies over damage an earthquake caused to his home.
Scott Ausbrooks of the Arkansas Geological Survey said a network of cracks and joints in underground rock formations allowed the fracking fluids to reach the fault and cause earthquakes. The earthquakes began rumbling through the countryside after the injections began, and after the operations stopped, the number of earthquakes dropped by two-thirds.
Ausbrooks pointed out that not all fracking operations cause seismic activity, but drillers should have a good understanding of the geology of an area before drilling.