State regulators suspended operations at two deep-injection wells for fracking wastewater in northeastern Ohio yesterday after discovering possible evidence that the operation caused a 2.1-magnitude earthquake last weekend.

State regulators suspended operations at two deep-injection wells for fracking wastewater in northeastern Ohio yesterday after discovering possible evidence that the operation caused a 2.1-magnitude earthquake last weekend.

The Ohio Department of Natural Resources issued a chief�s order to American Water Management Services for its Weathersfield site near Warren, an agency spokeswoman said. Messages seeking comment were left for the company after regular business hours.

Agency spokeswoman Bethany McCorkle called Sunday�s quake �relatively minor.� She said the suspension is effective pending a full investigation.

American Water Management Services recently had received permission to increase pressures at its Weathersfield site.

The citizens group Frackfree Mahoning Valley had called for an immediate halt to deep injection at the wells after the earthquake.

�The suspension was a prudent thing to do,� said Youngstown State University geologist Ray Beiersdorfer, who is affiliated with the group. He said he hopes the state will release more information regarding the pressures at the Weathersfield site after its investigation.

The Marcellus and Utica shale fields, rich in natural gas and oil, lie deep underneath parts of Ohio, Pennsylvania, Maryland, New York and West Virginia. More than 6,000 wells have been drilled there in the past five years.

In 2012, Gov. John Kasich halted disposal of fracking wastewater surrounding a well site in the same region after a series of earthquakes were tied to a deep-injection well. The company that ran that well has disputed the link.

The state placed seismic-monitoring devices in the Warren area under protocols adopted after the series of earthquakes in nearby Youngstown.