Does hydraulic fracturing cause earthquakes?

The National Research Council recently found that the “process of hydraulic fracturing a well as presently implemented for shale gas recovery does not pose a high risk for inducing felt seismic events.” Stanford University geophysicist Mark Zoback echoed these comments in 2012 in testimony to the U.S. Senate Committee on Energy and Natural Resources, stating that fracturing will “affect a very small volume of rock and release, on average, about the same amount of energy as a gallon of milk falling off a kitchen counter.”

You might not know it from some media reports, but seismic events actually are associated with what’s known as wastewater injection (disposal). These wells receive wastewater from a variety of industrial processes. While injection wells have been linked to seismic activity, according to the U.S. Geological Survey (USGS) the occurrence is rare: “Although the disposal process has the potential to trigger earthquakes, not every wastewater disposal well produces earthquakes. In fact, very few of the more than 30,000 wells designed for this purpose appear to cause earthquakes.” Senior USGS geophysicist Bill Ellsworth added that when disposal wells are linked with seismic activity, “it’s been fixed by either shutting down the offending well or reducing the volume that’s being produced. So there are really straight-forward fixes to the problem when earthquakes begin to occur.”