Seismologists see big increase in small quakes, say they appear related to drilling and injection wells

Researchers at the U.S. Geological Survey have concluded that a big increase in earthquakes in mid-America in the last decade "appears to be related to oil and gas drilling," reports Mike Soraghan of Energy & Environment News. While the quakes are generally small, the study looked at all U.S. quakes of magnitude 3 and greater since 2001.

"A remarkable increase in the rate of M 3 and greater earthquakes is currently in progress in the U.S. midcontinent," the scientists write in the short description of their study. "A naturally-occurring rate change of this magnitude is unprecedented outside of volcanic settings or in the absence of a main shock." While the changes "are almost certainly man-made, it remains to be determined how they are related to either changes in extraction methodologies or the rate of oil and gas production," the researchers write. Lead author William Ellsworth said he's confident fracking isn't responsible for the trends found in this study. They are to present their paper next month at the annual meeting of the Seismological Society of America in San Diego.

The paper examines potential causes, all of which "relate to drilling, or more specifically, deep underground injection of drilling waste," Soraghan reports. "Casting the quakes as a trend could make it more difficult for oil and gas companies and state regulators to discount the earthquakes related to drilling as rare, isolated events. That, in turn, could provide new ammunition to critics who want stronger regulations, or even a ban on drilling." (Read more)