The good people of Oklahoma were rattled on November 5 when the state was hit its largest earthquake on record, a 5.6-magnitude temblor that struck 44 miles east of Oklahoma City. (The previous biggest quake was a 5.5-magnitude tremor that hit in 1952.) Fortunately no one was hurt, though 14 homes were damaged in the initial quake, and the state was shaken by a number of moderate aftershocks.
Oklahoma isn't California—this is a state that is usually pretty seismically stable, one that had only about 50 small quakes a year until 2009. But the number of quakes spiked in 2009, and last year 1,047 tremors shook Oklahoma. All of which begs the question—has something changed to make the Sooner State unstable? Perhaps something like hydraulic fracturing?
Fracking—causing small fractures in the Earth miles beneath the surface with explosives in order to tap trapped oil and gas deposits—is common in Oklahoma, one of the centers of the fossil fuel extraction industry. And it's not hard to wonder whether injecting millions of gallons of water, sand and chemicals deep underground in order to break up rock might worsen existing faults or even trigger a tremor.
Read more:
http://ecocentric.blogs.time.com/2011/11/08/did-fracking-help-cause-oklahoma-earthquakes/#ixzz1d8Vn5qrY