By Kalea Hall
NEW CASTLE, PA.
The Pennsylvania Department of Environmental Protection is investigating five micro earthquakes in Lawrence County that occurred last Monday.
The quakes – all too small for people to feel – occurred not far from a well pad operated by Hilcorp Energy Co.
Subsequently, Houston-based Hilcorp voluntarily halted its nearby fracking operation about noon Monday.
The U.S. Geological Survey reports these earthquakes that day in Lawrence County:
12:05 a.m.: magnitude 1.9; 1.9 miles northeast of Bessemer, Pa.
4:16 a.m.: magnitude 1.7; 0.6 miles west of Oakland, Pa.
5:03 a.m.: magnitude 1.8; 1.2 miles east-southeast from Lowellville.
10:54 a.m.: magnitude 1.9; 2.5 miles northeast of Bessemer, Pa.
10:10 p.m.: magnitude 1.8; 1.9 miles northeast of Bessemer, Pa.
The DEP will meet with Hilcorp to discuss geologic data the company collected from the area during and before drilling. The Pennsylvania Department of Conservation and Natural Resources is investigating the quakes with the DEP.
Hilcorp has not returned a request for comment.
Hilcorp, doing business as North Beaver NC Development, has four wells on that well pad. The first two wells were fracked in a southeast direction and were completed, according to the department.
The second two wells were going in a northwest direction, and fracking was ongoing but near completion.
“That time and space correlation suggests that [the earthquakes and the fracking] are related,” said Michael Brudzinski, a professor of seismology in the Department of Geology and Environmental Earth Science at Miami University in Oxford, Ohio. “The operator was very proactive about it. They are cognizant that there’s something to be concerned about.”
In 2014, the private company had to stop its fracking operation in Poland Township after earthquakes hit near its well pad there.
The epicenter was directly below property owned by Republic Services’ Carbon Limestone Landfill, where Hilcorp Energy Co. had one well actively producing and a number of others being drilled at the time.
State regulators and geologists identified hydraulic fracturing as a “probable” trigger for the series of tremors in Poland Township.
The state’s investigation results came weeks after The Vindicator reported that geologists outside of ODNR were considering that fracking led to the local quakes in March 2014.
ODNR placed a moratorium on drilling at the Poland Township site, but Hilcorp is allowed to recover oil and gas from five previously drilled wells.
Geologists stressed how small the recent earthquakes in Lawrence County are.
An earthquake below magnitude-3 cannot be felt by a person. At the level of 3, the movement would feel like vibration felt when a semi-truck drives by, said Jeffrey Dick, professor of geology and chairman of the Geological and Environmental Sciences department at Youngstown State University.
The five earthquakes in Lawrence County are all most likely on the same fault line. A fault line is a break in the ground that occurs when the Earth’s plates move and are areas where earthquakes are likely to occur.
“That is what you’d expect,” Dick said.
Both Dick and Brudzinski explained how the rocks below the surface have pent-up stress and sometimes Mother Nature needs to release it.
If that is not the trigger to the earthquake, hydraulic fracturing could be.
Hydraulic fracturing, or fracking, is the process of injecting fluids and chemical additives at a high pressure into the earth to fracture rocks below the surface and extract oil and gas.
Dick thinks it’s “quite possible” fracking can trigger earthquakes.
Brudzinski, who completed a study about the Poland Township quakes, said there are two ways the fracking can trigger a quake: the stress of fracturing the rock may be enough to fracture other rocks nearby and get the fault to move, or the fluid injected into the rock could make its way to the fault line.
In Poland, it appeared the stress on the rock caused the earthquakes there, Brudzinski said.
“We do get some small earthquakes,” he said. “We want to rule out it is not just natural.”