A rash of earthquakes in the middle of the country appears to be related to oil and gas drilling, according to a group of researchers at the U.S. Geological Survey. "A remarkable increase in the rate of [magnitude-3.0] and greater earthquakes is currently in progress," the scientists state in the abstract for their study. "A naturally-occurring rate change of this magnitude is unprecedented outside of volcanic settings or in the absence of a main shock." The surge in temblors is "almost certainly man-made," they found, and all of the potential causes they explore in the paper relate to drilling, or more specifically, deep underground injection of drilling waste.