Radar data gathered by a Japanese satellite provides evidence that injecting wastewater from fracking into deep wells near Timpson, Texas, caused the ground to deform, and led to a magnitude 4.8 earthquake that shook the area back in May 2012.
The study, published in the journal Science on Sept. 23, found that the disposal of fracking wastewater put pressure on rocks and caused the ground to lift, up to nearly 5 miles from the well sites. The research further substantiates the link between fracking wastewater and earthquakes, which have increased sixfold in Texas and 160 times above historic levels in Oklahoma in recent years.
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Such orbital radar observations -- in this case, from the Japan Space Agency's Advanced Land Observing Satellite -- also could prove to be a useful tool for predicting such induced earthquakes in advance, an article on the work on Scientific American's website reports.
The team, which included Arizona State University's Manoochehr Shirzaei, Stanford University's William Ellsworth, Kristy Tiampo from the University of Colorado Boulder and the University of Liverpool's Pablo Gonzalez, studied several years' worth of radar data and focused on four injection wells near Timpson.
From May 2007 to November 2010, observed the ground rose 3 millimeters -- 0.118 inches -- annually above two of the wells, located about 1.25 miles apart.
"Our research is the first to provide an answer to the questions of why some wastewater injection causes earthquakes, where it starts and why it stops," co-author William Ellsworth, a geophysics professor at Stanford's School of Earth, Energy and Environmental Sciences, said in a press release.
The 2012 Timpson earthquake was part of a swarm of tremors in the area that spring along an earthquake fault in east Texas, which included five quakes ranging from 2.1 to 4.8 in magnitude, according to KTBS.com. Prior to that, the area had gone 30 years without any significant seismic activity, the local news website reported.
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The fracking process uses a high-pressure mix that includes sand, water and chemicals to crack rock formations and reach deposits of oil and gas. Some of that fluid is recycled and reused in fracking, but the process also creates wastewater -- which includes some chemical contamination, but mostly consists of brine brought to the surface with the gas and oil -- which must be disposed. That water is injected back into the earth in deep wells The U.S. Environmental Protection Agency, which regulates the disposal process, estimates that 2 billion gallons of brine are injected in the United States every day. Most oil and gas injection wells are in Texas, California, Oklahoma and Kansas.
A 2012 investigation by ProPublica linked injection wells of various sorts to contamination of groundwater, and warned that leaks posed a threat to the nation's drinking water supply.
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