By Will Drabold
For 100 years, Mahoning County had not experienced a sizable earthquake. But a little more than two years ago, the ground in the region started to shake. There have been a dozen earthquakes in the area near Youngstown since.
In fact, earthquakes have happened at a greater rate across Ohio in recent years than they had for more than a century.
On average, there were two quakes a year in Ohio greater than magnitude 2.0 between 1950 and 2009. But between 2010 and 2014, that average rose to nine, according to a Columbus Dispatch analysis of Ohio Department of Natural Resources data. Fracking became more prevalent during the same time period.
Nationwide, an average of 100 magnitude 3.0 or higher temblors occurred each year between 2010 and 2012. The average annual rate from 1967 to 2000 was 21, according to the U.S. Geological Survey.
In Mahoning County, an injection well began pumping millions of gallons of fracking waste into underground caverns near Youngstown in 2011. A series of earthquakes followed, and the state ordered the injection well to be shut down. Earthquakes across the nation have been blamed on injection wells.
In the past year, several fracking wells were drilled near Lowellville, and at least one began producing oil and gas. A series of earthquakes followed in the past two weeks, and the state ordered a nearby fracking well to be shut down.
Although state officials say they don’t know whether fracking caused the earthquakes — it would be a first in the United States — geologists worry that the two are connected.
Arthur McGarr, a U.S. Geological Survey geologist who is leading a national study on man-made earthquakes, said he, too, is curious about the lastest Mahoning County temblors.
“If these earthquakes are the direct results of the fracking operations, it’s fairly unusual, and it’s a good mystery that needs to be solved,” McGarr said.
He said his agency is considering placing its own portable seismometers in the area if ODNR doesn’t take measurements.
Mark Bruce, an ODNR spokesman, said the department is considering the option. In the meantime, the agency is reviewing data from Texas-based Hilcorp Energy, which operates the Lowellville wells.
Questions about the area’s geology and drilling went unanswered recently by ODNR officials and several state geologists, who said they were told not to comment.
Hilcorp owns eight fracking wells in Mahoning County. One was shut down after the most-recent earthquakes, but another continues to operate nearby. The company would not comment on its operations.
The county has one known fault line running through it — in its southwestern corner, said Mark Baranoski, a geologist with the state’s Division of Geological Survey.
“We know more about the surface of the moon then we do about the basement in Ohio,” he said.
There might be many other fault lines that won’t reveal themselves until additional earthquakes are recorded.
After the 2011 earthquakes near Youngstown, researchers found that a fracking-waste injection well linked to them had been drilled on an ancient fault line.
The fracking waste that was pumped more than 9,000 feet below the surface triggered the earthquakes, said Won Young-Kim, a senior scientist who runs a regional earthquake-monitoring network at Columbia University in New York.
Fracking involves pumping millions of gallons of water, sand and chemicals underground to shatter shale and free trapped oil and gas. The process can take days or weeks, and wells can be refracked.
During the fracking process, some of the fluids bubble back up with the gas. Oil and gas wells also produce saltwater contaminated with metals and radioactive materials that have been trapped underground for millions of years.
Kim said he is concerned that during fracking, fluids can push through porous rocks deep below ground and find “weak zones” or fault lines.
Tom Stewart, with the Ohio Oil and Gas Association, said no one should jump to the conclusion that fracking caused the quakes.
“Most experts will say the correlation of a seismic event, some rumbling from a hydraulic fracturing operation is extremely rare,” Stewart said. “At this stage, good scientific analysis is crucial to the process.”
Dispatch Reporter Jennifer Smith Richards and Assistant Metro Editor Doug Caruso analyzed data for this story. Will Drabold is a fellow in Ohio University’s E.W. Scripps School of Journalism Statehouse News Bureau.