There is new evidence that small earthquakes triggered by hydraulic fracturing or fracking rocked Ohio’s Harrison County in late 2013.
The nearly 500 micro-quakes occurred from early October to mid-December near Clendening Lake in an area with no recorded earthquakes, according to seismologist Paul A. Friberg of the New York-based Instrumental Software Technologies Inc., a private company specializing in seismology analysis and equipment, who has co-authored a scientific paper on the quakes.
The little-known Harrison quakes were the fifth "positive magnitude" quakes in the world to be triggered by hydraulic fracturing and the second in Ohio. Similar quakes were reported in Mahoning County last March.
The quakes trouble activists like Paul Feezel, who heads up Carroll Concerned Citizens, a grass-roots group in Carroll County. "It is quite worrisome…and a big concern," he said.
The Clendening quakes occurred within a half mile of three Utica shale horizontal wells that were fractured from Sept. 7 to Oct. 6 by Oklahoma-based Gulfport Energy Corp.
In hydraulic fracturing, water, sand and certain chemicals are injected under pressure into underground laterals that can be more than 2 miles in length to pulverize the black shale and free up natural gas and liquids that can be pumped to the surface.
The Harrison quakes were small, generally 2.0 magnitude or smaller, Friberg said.
"Magnitude 2s this deep will not be felt and do not cause any damage at the surface," he said. "The Harrison events were very small and were not significant to the public in that they were not felt and could have caused no problems," he said.
The largest quake at the Ryser wells in Moorefield Township was 2.2 magnitude. Two others were 2.0.
The quakes occurred at a depth of nearly 10,000 feet, nearly 2,000 feet below the Utica shale that was being fracked, he said.
The quakes started after the fracking was completed on those wells, and there is no evidence of additional quakes later, he said.
They occurred along an unmapped fault deep below ground. What happened to trigger the quakes is unclear, but a possible scenario is that pre-existing fluid-filled pathways in the rock "felt the pressure" from the fracking fluid and caused the fault to rupture, Friberg said.
One of Friberg’s co-authors was Glenda Besana-Ostman, a former seismologist with the Ohio Department of Natural Resources, now with the U.S. Department of Interior’s Bureau of Reclamation in Denver. The third co-author was Ilya Dricker of ISTI, based in New Paltz, N.Y.
The researchers concluded that the fracking process at Clendening probably triggered an earthquake tied to an unknown fault in the underground rocks.
The evidence also indicates that there are faults in the basement or lowest level rocks that can be activated by fracking.
Two sets of state-of-the-art equipment were in place to detect the Harrison quakes, Friberg said.
His company used data from previously installed temporary seismic station as part of the Earthscope Transportable Array Project that included 400 seismographs around the United States.
In addition, ODNR had installed four sensors in Harrison County to measure quakes from injection wells used for liquids disposal.
The information about the Harrison quakes was not a secret but it’s something that few people in Ohio have heard of.
A scientific paper has been written by Friberg and Besana-Ostman and it is out for peer review and not yet been released. They have made presentations at professional meetings in Alaska and California.
Until the report is released, it was premature to say too much about the Harrison quakes, Friberg said. He said he feels more comfortable talking about the quakes now since the paper is in review.
He called what happened in Harrison County to be "scientifically interesting quakes."
He added, "This is the second finding of hydraulic fracture-induced positive magnitude quakes that has been reported in the USA, the first being in Oklahoma." The Mahoning quakes were the third such case.
Many smaller quakes including negative magnitudes were detected at Clendening, he said.
Quakes are measured by the Richter scale, a logarithmic scale that goes to negative magnitudes for ultra-small quakes.
It is interesting to Friberg that many of the Harrison quakes were positive magnitude. Fracking usually triggers only negative magnitude quakes.
"Quakes from fracking are rare," said Friberg in an email.
That, he said, makes Harrison County the fifth case of fracking causing positive magnitude quakes in the world. The other locations were in Oklahoma, the United Kingdom, British Columbia and Mahoning County.
Ohio had a series of quakes last spring in Mahoning County’s Poland Township where wells were being fracked by Texas-based Hilcorp Energy Co. There were five quakes of 2.0 or greater.
Ohio said there was a "probable connection" between fracking, an unknown microfault and the Mahoning quakes.
The state ordered an indefinite moratorium on fracking natural gas wells within three miles of the epicenter of earthquakes on March 10 and 11. Ohio also changed its permit conditions for drilling in Ohio near faults or earthquake sites.
Nathan Johnson and Melanie Houston of the Ohio Environmental Council questioned why ODNR took quick action in the Mahoning case but took no action and made no announcements about the Harrison County quakes. The state’s lack of transparency in Harrison County is "deeply concerning," he said.
The state took no action there "because there was no action to be taken," said ODNR spokesman Mark Bruce.
The quakes were small and insignificant and the fracking was done before the quakes occurred, he said.
The Harrison quake data came from non-state sources and the state’s OhioSeis network did not record the Harrison quakes, he said.
The quakes in Mahoning and Harrison counties were different in terms of what Ohio knew and what Ohio could do, Bruce said.
Ohio had sufficient state-produced data in Mahoning County to step in while the fracking was under way, but the state agency lacked sufficient, state-produced data in Harrison County, he said.
"In Harrison County, we didn’t have enough data and we didn’t have the right data," he said. "From the regulatory standpoint, we couldn’t make that connection."
ODNR did not try to hide or cover up the Harrison quakes, said spokeswoman Bethany McCorkle.
Friberg said drillers need to be aware that their fracking fluids intersecting with unmapped faults may trigger Ohio earthquakes.
Monitoring earthquakes around a frack site through a seismic network will alert drillers and prevent larger positive magnitude quakes from occurring by allowing drillers to bypass zones that are causing smaller quakes, he said.
Requiring such monitoring is "a good first step" because it is very difficult to identify all the underground fault lines that could trigger quakes. he said.
Such frack-induced quakes appear more likely to occur in the Utica shale than the Marcellus shale in Pennsylvania, Friberg surmised. That’s because the Utica shale is deeper and closer to the older basement rocks where unknown faults are more apt to exist, he said.
There is significantly more evidence that injection wells can trigger earthquakes. That is what happened in the Youngstown area in late 2011 and early 2012 where a now-closed injection well triggered quakes as large as 4.0.
There have also been reports of earthquakes in Oklahoma, Texas and Arkansas linked to injection wells.
Chesapeake Energy Corp,the Oklahoma-based firm is the No. 1 driller in Ohio.
Rig Count Interactive Map by Baker Hughes, an energy services company.
Shale Sheet Fracking, a Youngstown Vindicator blog.
The Ohio Environmental Council, a statewide eco-group based in Columbus.
Earthjustice, a national eco-group.
People's Oil and Gas Collaborative-Ohio, a grass-roots group in Northeast Ohio.
Concerned Citizens of Medina County, a grass-roots group.
No Frack Ohio, a Columbus-based grass-roots group.
Fracking: Gas Drilling's Environmental Threat by ProPublica, an online journalism site.
Pipeline, blog from Pittsburgh Post-Gazette on Marcellus shale drilling.
Allegheny Front, environmental public radio for Western Pennsylvania.