The abstract does not explicitly link rising earthquake activity to fracking – known formally as hydraulic fracturing – that involves pumping water and chemicals into underground rock formations to extract natural gas and oil.
But the wastewater generated by fracking and other extraction processes may play a role in causing geologic faults to slip, causing earthquakes, the report suggests.
“A remarkable increase in the rate of (magnitude 3) and greater earthquakes is currently in progress,” the authors wrote in a brief work summary to be discussed Wednesday at a San Diego meeting of the Seismological Society of America.
“While the seismicity rate changes described here are almost certainly manmade, it remains to be determined how they are related to either changes in extraction methodologies or the rate of oil and gas production,” the abstract said.
From 1970 through 2000, the rate of magnitude 3 or greater quakes was 21 plus or minus 7.6 each year, according to USGS figures. Between 2001 and 2008, that increased to 29 plus or minus 3.5.
But the next three years saw the numbers increase “much more spectacularly,” said Arthur McGarr, of the geologic survey’s Earthquake Science Center in California: 2009 had 50, 2010 had 87 and 2011 had 134 such events.
“We don’t know why, but we doubt that it’s a natural process, because in nature, the only time you see such a big increase is during an aftershock sequence (with a series of quakes) or in a volcanic setting where you often get swarms of earthquakes due to magmatic activity,” McGarr said by telephone.
Source: Dawn News
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