The report by the National Research Council found that the most significant risk of earthquakes is linked to secondary injection of wastewater below ground to help capture remaining hydrocarbons from a petroleum reservoir.
Also, a technique called carbon capture and storage that aims to reduce carbon dioxide emissions to the atmosphere by capturing, liquefying and injecting them below ground at high volumes, “may have potential for inducing larger seismic events,” the report said.
But fracking, which offers the potential to unlock vast quantities of natural gas from shale formations and has come under intense scrutiny from environmentalists, was not a major risk factor for quakes that would be strong enough for people to feel, or above 2.0 magnitude, it said.