Correction: WTOP erroneously stated deep waste water injection wells are a process of "fracking." This waste water is actually a byproduct of fracking that is disposed of by being injected into a separate well elsewhere.
WASHINGTON - The increase in strong earthquakes from Kentucky to Colorado is "almost certainly" caused by human intervention, according to a new government study.
Last year saw a sharp rise in 3.0-magnitude quakes or stronger in the U.S. midcontinent, a continuing trend that prompted the U.S. Geological Survey -- the government's main source for Earth sciences -- to investigate the root cause.
Their resulting study, to be released publicly on Wednesday, states the rise from roughly 20 quakes of this strength in 2000 to over 134 in 2011 is "almost certainly manmade." The agency studied areas close to where deep waste water, the byproduct of "fracking," a method of extracting gasses, was injected into wells.
The study compares concentrations of earthquakes of 3.0-magnitude or greater in a section of midcontinent America in 2011, pictured in the graphic at right, with areas of dense fracking, outlined in the map below.
"A naturally-occurring rate change of this magnitude is unprecedented outside of volcanic settings or in the absence of a main shock, of which there were neither in this region," states the report, prepared by a USGS team led by Bill Ellsworth of the agency's Menlo Park, Calif. branch.
It remains undetermined that fracking is the direct cause of the quakes, the report states, but a recent blog post from the Department of the Interior -- aimed at clarifying the USGS study -- says that is a possibility, and that there is no way to tell if fracking is the cause.
"Although we cannot eliminate the possibility, there have been no conclusive examples linking waste water injection activity to triggering of large, major earthquakes even when located near a known fault," writes David J. Hayes, deputy secretary.
While the study does not prove the connection between quakes and fracking, Hayes writes the scientists found "the increase in seismicity coincides with the injection of wastewater in deep disposal wells."
There are no current methods to anticipate whether fracking could trigger an earthquake "large enough to be of concern," he says.
Check out the rate of 3.0-magnitude or greater earthquakes in recent years, which Ellsworth calls "a remarkable increase":
- 1970-2000 (per year): 21 (+/- 7.6)
- 2001-2008 (per year): 29 (+/- 3.5)
- 2009: 50
- 2010: 87
- 2011: 134
Last December, following a 4.0-magnitude quake in Ohio, a spokesman for the state's Department of Natural Resources said definitively fracking was not to blame.
The waste water injected into an Ohio well just before that earthquake had been shipped there from a fracking project in Pennsylvania, a USGS spokeswoman tells WTOP.
"The seismic events are not a direct result of fracking," said Director Jim Zehringer during a news teleconference.
Northstar Disposal Services LLC injected thousands of gallons of brine daily into a well outside of Youngstown, Ohio, adjacent to the quake's epicenter. They agreed to stop pending a state investigation into the cause of the quake.
Last August's 5.8 tremor that shook the D.C. region was centered in Mineral, Va. The Old Dominion currently has 7,700 natural gas wells in operation as of February, according to a Washington Post report. Communities in that state and neighboring Maryland recently have resisted new drilling sites, particularly into the rich Marcellus Shale, following negative publicity about the fracking process leading to pollution and the contamination of groundwater.
View USGS Fracking/Earthquake Study in a larger map
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