‘Fracking’ for Natural Gas Is Linked With Earthquakes
Hydraulic fracturing (a.k.a. “fracking”) recovery techniques for oil and natural gas are a controversial business. The practice—in which a mix of water, sand and chemicals is injected deep into bedrock at high pressure to create fractures, allowing gas and oil to flow upward—was developed in the late 1990s and has become more and more common across the United States over the past few years, opening up geologic areas such as the Bakken Shale in North Dakota and the Marcellus Shale in Pennsylvania, New York and West Virginia to dramatic increases in gas production.
On the one hand, proponents argue that hydraulic fracturing increases the amount of energy that can be economically produced in the United States, making oil and gas cheaper and reducing our dependency on foreign imports. Opponents, though, note that fracking causes dangerous chemicals to leach into groundwater, releases known carcinogens into the air and increases our contribution to climate change.
Alongside these observed problems, though, a different sort of worry has emerged: the idea that hydraulic fracturing can trigger an earthquake. Scientists have known for decades that injecting fluids into the earth could cause quakes, but we were uncertain just how much of an increase widespread fracking might cause. This past spring, USGS scientists decided that the recent dramatic increase in the number of small quakes in the United States is “almost certainly manmade,” but were unable to conclusively tie it to this particular activity.
Now, the evidence is starting to pile up. A study published today in the Proceedings of the National Academy of Sciences finds a correlation between dozens of small earthquakes in Texas’ Barnett Shale region—the site of intensive hydraulic fracturing activity—and the locations of injection wells used to dispose of the wastes of this process. “You can’t prove that any one earthquake was caused by an injection well,” says Cliff Frohlich, the University of Texas geologist who conducted the study, “but it’s obvious that wells are enhancing the probability that earthquakes will occur.”