The U.S. Geological Survey (USGS) on Sunday recorded a small earthquake in Weathersfield Township, OH, about 12 miles northwest of Youngstown, in Trumbull County, but it remains unclear if two nearby underground injection wells are to blame.
USGS initially recorded a 1.8-magnitude quake in the area Sunday but revised the figure to a 2.1-magnitude Tuesday, which was not strong enough for residents in the area to feel, according to the agency. Although two injection wells accepting oil and gas waste were located at the quake's epicenter, neither a small Ohio-based company operating those wells nor regulators at the Ohio Department of Natural Resources (ODNR) have enough information to link the seismic activity to them.
"ODNR is reviewing both data from seismic monitoring equipment and operating Class II injection wells in the area surrounding the recent seismic event in Trumbull County," ODNR spokesman Mark Bruce said. "The review of this data will allow ODNR to determine if any correlation can be made and whether or not any regulatory action is necessary."
Northeast Ohio has experienced a series of small earthquakes in recent years that have been tied to oil and gas operations. In March, ODNR shut down operations at a six-well pad in Poland Township, about eight miles southeast of Youngstown, after a 3.0-magnitude earthquake was recorded in the area (see Shale Daily, March 11; March 12).
Regulators later determined that Hilcorp Energy Co. had been stimulating a well there and said a month later that those operations likely caused the seismic activity (see Shale Daily, April 11). On New Year's Eve 2011, a 4.0-magnitude earthquake was recorded and ODNR later linked an injection well in Youngstown to that event (see Shale Daily, Jan. 4, 2012).
The department has since installed a network of seismic monitors in the area to keep track of such events (see Shale Daily, May 22). It also now requires a special permitting process for unconventional drilling within three miles of a known fault line.