A rash of earthquakes in the middle of the United States appears to be related to drilling for natural gas, according to researchers at the U.S. Geological Survey.
The surge in quakes "is almost certainly man-made," the scientists said in an abstract for their study.
Deep underground injection of drilling wastes appears the likely culprit.
The study found 50 earthquakes of magnitude 3.0 or greater in 2009 in an area from Alabama to Montana. That number grew to 87 in 2010 and 134 last year.
"This is very peculiar, what's going on," report author and geophysicist William Ellsworth told EnergyWire.
In Ohio, the Youngstown area has had 13 quakes in the last year near a now-closed injection well where brine wastes were pumped deep underground for disposal.
The paper is to be presented next month at a meeting of the Seismological Society of America in San Diego. The abstract has been released.
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