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Geologists from the University of Miami report that hydraulic fracturing, or fracking, caused 77 small earthquakes in northeastern Ohio, an area that is normally geologically quiet.
Their study, published online on Jan. 5 by the Bulletin of the Seismological Society of America, said energy companies caused the quakes in March 2014 as a result of fracking into an underground area near Youngstown, Ohio, that contained a previously unknown geological fault.
Seismic data determined that the earthquakes ranged in magnitude from 1.0 to 3.0 on the widely used Richter scale between March 4 and March 12, according to Robert Skoumal and Michael Brudzinski, geology professors at Miami, and graduate student Brian Currie.
They said the earthquake measuring 3.0 on the Richter scale, which occurred on March 10, was large enough to be felt by people on the surface in the vicinity of Poland Township, a few miles southeast of Youngstown.
The researchers matched the dates of the earthquakes with records of fracking activity in the area kept by the Ohio Department of Natural Resources. The two coincided.
But Skoumal said there was no way for the energy companies to know that their activities might be hazardous. “These earthquakes near Poland Township occurred in … a very old layer of rock where there are likely to be many pre-existing faults,” he said. “This activity did not create a new fault, rather it activated one that we didn’t know about prior to the seismic activity.”
In fact, the researchers’ article said fracking rarely causes earthquakes of enough magnitude to be felt on the surface. Often only the latest techniques of seismic monitoring can detect them, it said, yet their frequency is increasing because of the recent growth of fracking to extract oil and gas trapped in shale that otherwise would be inaccessible.
Another state not known for earthquakes is Oklahoma, but tremors have increased rapidly in the past several years, including one in 2011 with a magnitude of 5.7 on the Richter scale. However, research indicates that while these temblors are linked to fracking, it isn’t the procedure itself that’s to blame, but the disposal of the water used in fracking.
Research by Katie Keranen, an assistant professor of seismology at Cornell University in New York, found that injecting wastewater from fracking at underground disposal sites can cause earthquakes of moderate strength, or magnitude 3, by widening cracks in geological formations, increasing the chances of earthquakes.
Keranen’s research, published July 3 in the journal Science, backs up an earlier report by the U.S. Geological Survey (USGS) that found that some of the 450 earthquakes of magnitude 3 and larger in central and eastern parts of the United States between 2010 and 2013 coincided with the disposal of fracking wastewater.
In the University of Miami study, Skoumal didn't point a finger of blame, but recommended better communication among geologists, energy companies and local governments before any fracking is conducted.
“We just don’t know where all the faults are located,” Skoumal said. “It makes sense to have close cooperation … as hydraulic fracturing operations expand in areas where there’s the potential for unknown pre-existing faults.”
By Andy Tully of Oilprice.com
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Andy Tully is a veteran news reporter who is now the news editor for Oilprice.com