LOWELLVILLE - Two earthquakes shook the Mahoning Valley on Monday morning, resulting in the suspension of all oil and gas drilling activity in the area.
The seismic activity, centered around the Lowellville area, began with a 3.0-magnitude earthquake at about 2:26 a.m., according to the U.S. Geological Survey.
Later in the morning, at 11:44 a.m., a 2.6-magnitude aftershock hit the region, resulting in a barrage of emergency calls in Lowellville, Poland and Boardman.
Although officials with the Ohio Department of Natural Resources have not definitively linked the seismic activity to oil and gas production and wastewater disposal in the area, drilling was shut down "until further assessments can take place."
"All available information indicates the events are not connected to Class II injection activities," said Mark Bruce, ODNR spokesman. "Out of an abundance of caution, we notified the only oil and gas operator in the area and ordered them to halt operations."
The only Utica shale wells in the reported epicenter are operated by Hilcorp Energy Company and are located at Poland's Carbon Limestone Landfill.
In a statement released Monday afternoon, Hilcorp said it was fully cooperating with ODNR to suspend drilling activity while the cause is investigated.
"It is far too early in the process to know exactly what happened, and we are not aware of any evidence to connect our operations to these events," the release states. "Nevertheless, we do acknowledge that public safety is of paramount importance to our company."
According to Hilcorp, the company has no active injection or wastewater disposal wells in the area, and only one of the wells is currently producing oil and gas.
"There are currently seven wells on two pads at that site in various stages of development," the release states. "Only one is producing oil and gas at the moment."
It remains unclear for how long activity at the Hilcorp wells will be suspended.
The connection between hydraulic fracturing and deep underground waste disposal to seismic tremors has been the focus of research and controversy since a series of 11 minor quakes in the Youngstown area in 2011, capped off by a 4.0-magnitude earthquake on New Year's Eve.
A report ultimately released by the Ohio Department of Natural Resources concluded the well owned by D&L Energy Systems had been drilled into a previously undiscovered geologic fault line.
The resulting ODNR report suggested that the earthquakes were the result of brine water lubricating that fault line and causing it to slip.
Regulatory officials vowed to do a complete investigation of Monday morning's seismic activity.
"ODNR is using all available resources to determine the exact circumstances surrounding this event and will take the appropriate actions necessary to protect the public health and safety," Bruce said.