Geologists have for the first time linked earthquakes deep under Ohio's Appalachian Mountains to hydraulic fracturing, leading the state to issue strict permit conditions Friday on the gas extraction process.
Researchers found that five small tremors last month near Youngstown, Ohio were likely the result of the injection of sand and water that occurs during the hydraulic fracturing -- or "fracking" -- process, the Associated Press reports. Fracking involves injecting rocks with pressurized water or other liquids in an effort to extract gas which can be turned into usable fuel.
Because the geology of each shale formation is different, the discovery in Ohio may not apply everywhere across the country. However, other instances of fracking causing small earthquakes have been recorded elsewhere, including in Oklahoma, England and British Columbia, Canada.
Ohio's new permit conditions require natural gas companies to install sensitive seismic-monitoring equipment at drilling sites near known faults or seismic activity. If an earth tremor of greater than 1.0 magnitude is linked to fracking, operations will be halted.
"While we can never be 100 percent sure that drilling activities are connected to a seismic event, caution dictates that we take these new steps to protect human health, safety and the environment," James Zehringer, director of Ohio's natural resources department, said.
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