On 5 November an earthquake measuring 5.6 rattled Oklahoma and was felt as far away as Illinois.
Until two years ago Oklahoma typically had about 50 earthquakes a year, but in 2010, 1,047 quakes shook the state.
In Lincoln County, where most of this past weekend's seismic incidents were centered, there are 181 injection wells, according to Matt Skinner, an official from the Oklahoma Corporation Commission, the agency which oversees oil and gas production in the state.
Cause and effect?
The practice of injecting water into deep rock formations causes earthquakes, both the U.S. Army and the U.S. Geological Survey have concluded.
The U.S. natural gas industry pumps a mixture of water and assorted chemicals deep underground to shatter sediment layers containing natural gas, a process called hydraulic fracturing, known more informally as “fracking.” While environmental groups have primarily focused on fracking’s capacity to pollute underground water, a more ominous byproduct emerges from U.S. government studies – that forcing fluids under high pressure deep underground produces increased regional seismic activity.
As the U.S. natural gas industry mounts an unprecedented and expensive advertising campaign to convince the public that such practices are environmentally benign, U.S. government agencies have determined otherwise.
According to the U.S. Army’s Rocky Mountain Arsenal website, the RMA drilled a deep well for disposing of the site’s liquid waste after the U.S. Environmental Protection Agency “concluded that this procedure is effective and protective of the environment.” According to the RMA, “The Rocky Mountain Arsenal deep injection well was constructed in 1961, and was drilled to a depth of 12,045 feet” and 165 million gallons of Basin F liquid waste, consisting of “very salty water that includes some metals, chlorides, wastewater and toxic organics” was injected into the well during 1962-1966.