"Geologists in Ohio have for the first time linked earthquakes in a geologic formation deep under the Appalachians to hydraulic fracturing, leading the state to issue new permit conditions Friday in certain areas that are among the nation's strictest.

A state investigation of five small tremors last month in the Youngstown area, in the Appalachian foothills, found the injection of sand and water that accompanies hydraulic fracturing, or fracking, in the Utica Shale may have increased pressure on a small, unknown fault, State Oil & Gas Chief Rick Simmers told the Associated Press. He called the link "probable."

Fracking involves pumping huge volumes of water, sand and chemicals underground to split open rocks to allow oil and gas to flow. Improved technology has allowed energy companies to gain access to huge stores of natural gas but has raised widespread concerns that it might lead to groundwater contamination — and also earthquakes."

Aljazeera America had the story April 12, 2014. [2]