3.9 Earthquakes Shake Arkansas, Some Doubt 'Fracking' Link

Arkansas has been wracked by an unusual rash of earthquakes which has prompted the state to halt fracking for natural gas because of the possibility that injections of toxic fracking waste liquids deep underground might be contributing to the seismic activity. There's been a moratorium on fracking in the state since March 4.
http://www.huffingtonpost.com/2011/04/09/arkansas-earthquakes-2011_n_847040.html