Regulators and energy industry executives in Oklahoma are playing close attention to recent earthquake-related developments in Ohio.
The head of the Ohio Department of Natural Resources ordered changes to the conditions for issuing drilling permits last Friday, after state geologists concluded that a connection between hydraulic fracturing and a series of small earthquakes was "probable."
The study, which is expected to be presented at a seismology conference in Alaska in two weeks, reportedly suggests that the process of fracking itself – not the disposal of fracking wastewater into deep injection wells – triggered as many as five small magnitude quakes in Ohio in March.
It's been well-documented that the injection of wastewater, or other fluid, into disposal wells can cause earthquakes, especially when the well is situated close to a fault. Far more elusive, however, has been evidence directly linking earthquakes to hydraulic fracturing.
Under the amended permitting rules, oil and gas companies wanting to drill within three miles of a known fault or previous seismic activity (magnitude 2.0 or greater) must install sensitive seismic monitors at those locations. If one of those seismometers then detects a tremor of magnitude 1.0 or higher, activity at the associated drill site must immediately halt so that investigators can determine if there is a causal relationship between the drilling and the seismicity.
ODNR Director James Zehringer calls the new restrictions "a reasonable course of action to help ensure public safety."
Industry representatives in Ohio are withholding judgment for the moment.
"These are very aggressive and cautious measures to minimize the risk of felt induced seismicity," said Shawn Bennett, of Energy in Depth Ohio. "The industry is actively reviewing these new permit conditions."
Oklahoma Geological Survey research seismologist Austin Holland found a similar connection in Oklahoma between fracking and earthquakes. In a study published last year, Holland laid out evidence suggesting about 50 earthquakes in Garvin County in 2011 were triggered by a nearby fracking operation.
There have been no changes to the permitting process, however, in Oklahoma.
The director of the Oklahoma Geological Survey, Randy Keller, said, "There are no new regulations because there is no indication that any seismicity due to fracking poses a hazard that would warrant such a step."
Mike Terry, president of the Oklahoma Independent Petroleum Association, points out that there's been fracking in Oklahoma since 1949, and yet it's only been in the last few years that the state's earthquake numbers have risen.
"If hydraulic fracturing was a leading cause of seismic events," said Terry, "Oklahoma would have seen increased seismicity long ago."