A dozen earthquakes in northeastern Ohio were almost certainly induced by injection of gas-drilling wastewater into the earth, Ohio oil and gas regulators said Friday as they announced a series of tough new regulations for drillers.

Among the new regulations: Well operators must submit more comprehensive geological data when requesting a drill site, and the chemical makeup of all drilling wastewater must be tracked electronically.

Northeastern Ohio and large parts of adjacent states sit atop the Marcellus Shale geological formation, which contains vast reserves of natural gas that energy companies are rushing to drill using a process known as hydraulic fracturing.

The state Department of Natural Resources announced the tough new brine injection regulations because of the report's findings on the well in Youngstown, which it said were based on "a number of coincidental circumstances."

For one, investigators said, the well began operations just three months ahead of the first quake. They also noted that the seismic activity was clustered around the well bore, and reported that a fault has since been identified in the Precambrian basement rock where water was being injected.

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