The brine wastewater comes from drilling operations that use the so-called fracking process to extract gas from underground shale. But Ohio Department of Natural Resources Director Jim Zehringer said during a news teleconference that fracking is not causing the quakes.
"The seismic events are not a direct result of fracking," he said.
Environmentalists and property owners who live near gas drilling wells have questioned the safety of fracking to the environment and public health. Federal regulators have declared the technology safe, however.
Zehringer said four injection wells within a five-mile radius of an already shuttered well in Youngstown will remain inactive while further scientific research is conducted.
A 4.0 magnitude quake Saturday afternoon in McDonald, outside of Youngstown, was the 11th in a series of minor earthquakes in area, many of which have struck near the Youngstown injection well. The quake caused no serious injuries or property damage, Zehringer said.