A series of 77 earthquakes in Ohio — including one strong enough to be felt by humans — was caused by the controversial process of hydraulic fracturing, scientists claimed in research published Tuesday in the Bulletin of the Seismological Society of America (BSSA).
Small earthquakes have been attributed to fracking in Ohio before. But those earthquakes were all too small to be felt. Tuesday’s study is the first time scientists have attributed a larger earthquake to fracking, the process of injecting high-pressure water, sand, and chemicals underground to crack shale rock and let gas flow out more easily.
The scientists, from the University of Miami, identified 77 earthquakes of varying size in the Poland Township of Ohio, all occurring between March 4 and March 12 and all located near a group of oil and gas wells. The quakes ranged between magnitudes of 1.0 and 3.0, but the local community reportedly only felt one, a magnitude 3.0 on March 10.
According to study co-author Robert Skoumal, that magnitude 3.0 quake was “one the largest earthquakes ever induced by hydraulic fracturing in the United States.”
To make his determination, Skoumal and his colleagues compared the series of earthquakes to reports that showed the timing of fracking at those oil and gas wells, all operated by Hilcorp Energy. They found the earthquakes “coincided temporally and spatially with hydraulic fracturing at specific stages of the stimulation,” the BSSA said in a press release.
The research doesn’t prove that all fracking causes earthquakes, but it does suggest that fracking occurring near fault lines has the potential to cause them. The BSSA noted that the 77 Ohio quakes occurred along one fault line within .06 miles of the well sites, and that fracking occurring at other nearby wells not near that fault line produced no seismicity.
“It appears that a relatively small portion of the operation is responsible for the events,” Skoumal said in the press release. ”
Because of that, Skoumal recommended “cooperation among government, industry and the scientific community” to try to prevent fracking operations in places where there may be known or unknown faults. As it turns out, seismologists did not know about the fault near the oil and gas wells owned by Hilcorp until Skoumal and his colleagues undertook the study.
In comments to the Pittsburgh Post-Gazette, Ohio Department of Natural Resources spokeswoman Bethany McCorkle said the findings were consistent with what scientists have previously stated is a “probable” link between fracking and earthquakes in Ohio. Just this past October, seismologists Paul Friberg, Ilya Dricker, and Glenda Besana-Ostman discovered a previously undiscovered fault line approximately two miles below three horizontal gas wells near the town of Uhrichsville, Ohio. The researchers say they detected 190 tiny earthquakes below one of those wells during a 39-hour period starting just after that well was fracked.
That research, and the research published Tuesday, differs from other research linking fracking to earthquakes. While the latest research credits earthquakes to the process of fracking itself, most other studies instead credit the process of wastewater injection: a.k.a, taking the leftover water used to frack the well and disposing of it by injecting it back underground. Scientists increasingly believe that the underground fluid migrates along dormant fault lines, re-activating them and causing earthquakes.
The research linking fracking and the wastewater disposal process to earthquakes is still preliminary, but evidence is getting stronger. Seismologists say more research needs to be done on the subject, particularly because it’s so difficult to tell which seismic events are natural and which others are caused by human activity
Ohio has some of the strictest rules governing fracking-induced earthquakes in the country. Concerned with increasing reports of seismic activity in fracking-rich states, Ohio’s government in April announced that it would begin requiring oil and gas companies to install earthquake monitors before drilling within three miles of a known fault line, or in any area that has ever experienced an earthquake greater than a 2.0 magnitude. If those monitors detect a quake of 1.0 or more, the company has to halt its operations, and regulators must investigate whether drilling was the cause.