By Don Hopey / Pittsburgh Post-Gazette
A new scientific study has linked 77 minor earthquakes last March around Poland, Ohio, just across the Pennsylvania-Ohio state line, to hydraulic fracturing.
The seismic sequence, including a rare “felt” quake of a magnitude 3.0 on the Richter Scale, was linked to active “fracking” by Hilcorp Energy Co. on a well pad about a half mile from the epicenter, according to research published online in the Bulletin of the Seismological Society of America.
One of the study’s authors, Robert Skoumal, of Miami University of Ohio, said it is rare for deep fracking operations associated with shale gas extraction to cause earthquakes large enough to be felt by people on the surface. But seismic monitoring advances have found the number of “felt and unfelt” earthquakes associated with fracking have increased over the past 10 years.
“These earthquakes near Poland Township occurred in the Precambrian basement, a very old layer of rock where there are likely to be many pre-existing faults,” Mr. Skoumal said in the news release about the findings. “This activity did not create a new fault, rather it activated one that we didn’t know about prior to the seismic activity.”
The researchers, Mr. Skoumal, Michael Brudzinski and Brian Currie, used a technique called “template matching” to link fracking activity on certain dates to seismic data recorded by the Earthscope Transportable Array, a network of seismic stations.
The study identified 77 deep earthquakes, with magnitudes from 1.0 to 3.0, to the fracking done around Poland, which is 15 miles west of New Castle, in Lawrence County. Only fracking on wells located in the northeast portion of Hilcorp’s shale gas operations were linked to the earthquakes, indicating where faults may be located.
“We just don’t know where all the faults are located,” said Mr. Skoumal in the release. “It makes sense to have close cooperation among government, industry and scientific community as hydraulic fracturing operations expand in areas where there’s the potential for unknown pre-existing faults.”