By Paresh Dave, Los Angeles Times

Ohio geologists have found a probable connection between fracking and several mild earthquakes in a region that had never experienced a temblor until recently, according to a state report.

The report, which coincided with Ohio’s announcement of some of the nation’s strictest limits on fracking near faults, marked the strongest link to date between nerve-rattling quakes and hydraulic fracturing — the process of firing water, sand and chemicals deep into the earth to extract oil and natural gas from ancient rock.

Last month, the state indefinitely shut down Hilcorp Energy Co.’s fracking operation near the Pennsylvania border after five earthquakes, including one magnitude 3 temblor that shook many Ohioans awake.

Federal scientists have previously linked earthquakes in part to the use of injection wells, where post-fracking wastewater is forced back deep into the earth for storage. None of the seven wells near the Ohio quakes were used for waste disposal, leaving Ohio scientists to go a step further to find a significant relationship between the initial blast of fluid and the earthquakes shortly thereafter.

They “believe the sand and water injected into the well during the hydraulic fracturing process may have increased pressure on an unknown microfault in the area,” the Ohio Department of Natural Resources said in a statement about the operation in Poland, Ohio.

The new rules require companies to install “sensitive seismic monitors” before beginning to drill sideways into underground rock “within 3 miles of a known fault or area of seismic activity greater than a 2.0 magnitude.”

Humans can generally feel earthquakes in excess of magnitude 3.

Drilling would be suspended pending investigation whenever the monitors detect anything above magnitude 1.

“While we can never be 100 percent sure that drilling activities are connected to a seismic event, caution dictates that we take these new steps to protect human health, safety and the environment,” department Director James Zehringer said.

Data gathered by the monitors would be used to improve fault maps, he said.

Hilcorp Energy said that it was reviewing the new permitting rules and that it remained “fully committed to public safety and acting in a manner consistent with being a good corporate citizen.”

Officials from Ohio and several other states that have seen an increase in seismic activity met recently to discuss how to handle the expansion of fracking to new beds of rock, where faults might not be well mapped.

Gerry Baker, associate executive director of the Interstate Oil and Gas Compact Commission, called Ohio’s new rules a “sensible response to a serious issue that regulators across the country are closely examining.”

Oklahoma, Texas, Arkansas and Kansas have been among those seeing the largest surges in seismic activity.

Critics of fracking have long warned of a possible connection between earthquakes and the expanded drilling for oil and gas in shale deposits. They have also raised concerns about possible groundwater contamination by fracking chemicals.

Ray Beiersdorfer, a Youngstown State University geology professor whose wife co-founded Frackfree America, said the new regulations mirrored what he had been seeking.

He has asked Ohio officials to make public the data they used to find the connection as well as set the new restrictions.

“The whole problem is no one knows about these faults until the earthquakes happen because the faults haven’t been researched,” he said.

Oil and gas companies have tended to avoid the well-known fault lines in Ohio, according to the industry publication Natural Gas Intelligence. But industry leaders maintained there is scant evidence that fracking causes earthquakes and labeled the temblors isolated incidents.

At Hilcorp’s site directly above last month’s earthquakes, the state has banned further fracking but has allowed wells already fracked to resume operating.

“This is also expected to have the beneficial effect of reducing underground pressure and decreasing the likelihood of another seismic event,” the state said.

AFP Photo/Frederick Florin