Recent small earthquakes in Ohio were likely triggered by fracking, state regulators in Ohio said.
Reuters reports the Ohio Department of Natural Resources (ODNR) said that injecting sand, water and chemicals deep underground to help release oil and gas may have produced tremors in Poland Township last month.
The department announced stricter rules for oil and gas exploration and included that statement as a rise in earthquakes in Ohio and other areas has occurred.
Last month, drilling and fracking was suspended near the site of two earthquakes in Poland Township in the northeast of the state, 70 miles southeast of Cleveland, the first of which was magnitude 3.0, enough to be felt for miles around.
“Regarding the seismic events in Poland Township, ODNR geologists believe the sand and water injected into the well during the hydraulic fracturing process may have increased pressure on an unknown microfault in the area,” ODNR said in a statement.
The new rules require a company to install seismic monitors if it is drilling within three miles of a known fault or an area which has recently experienced quakes, the ODNR said. It is unclear how much drilling will be affected by the new rules.