A series of earthquakes hit eastern Ohio on March 10 prompting officials to halt hydraulic fracturing operations as they investigated the cause. The earthquake occurred in Mahoning County near seven drilling sites owned by Hillcorp Energy.
In a region that has not historically had a high frequency of earthquakes, the occurrence of earthquakes central and southern regions of the U.S. have increased by a factor of 20. After a well is fractured, the waste water is pushed back into the ground for storage in what are known as "injection wells." Scientists believe that there is evidence to support the idea that injection wells are contributing to the rise in earthquakes, rather than the "frack" job itself. However, the latest series of earthquakes occurred in an area without waste injection wells, but they were located near wells that are actively being drilled. This has raised questions about the connection between fracking and earthquakes.
The Ohio Department of Natural Resources suspended the drilling operations out of "an abundance of caution." Hilcorp Energy, the operator of the nearby wells, agreed with the agency.
Back in 2011 several large earthquakes hit near Youngstown, Ohio. Scientists have linked that incident with injection wells. Elsewhere, earthquakes have also seen an uptick in drilling areas. Oklahoma is now the second most seismically active area, after California. The oil and gas industry have argued that the link between injection wells and earthquakes is weak and needs more study before regulators halt drilling operations.
Eastern Ohio has seen a proliferation of drilling activity in the last few years. The industry has been able to rapidly increase production in this part of the state, pulling liquid rich natural gas and oil from the Marcellus and Utica Shales.