Experts suggest various causes for earthquakes in East Texas

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TIMPSON, Texas -- Timpson in Shelby County in East Texas has been home to eleven measurable earthquakes in the last four months. The area is also home to nearly 30 injection wells used to store waste water from hydraulic fracturing and other oil field processes.

So when the shelves started shaking and merchandise started falling at the Dollar General in Timpson, twice, on Monday anti-fracking activists were quick to make a presumed connection.

"We know that private property is being damaged and I want to know who's going to pay for that,” said Sharon Wilson with the environmental group Earthworks. "I'm not a scientist but it's common sense. I mean when you inject a lot of mass into the earth things have to move."

Oil industry representatives, however, have repeatedly pointed out that the Timpson area of East Texas has long been known for its fault lines and recorded earthquakes since the 1800s, long before injection wells or hydraulic fracturing.

“So now that earthquakes are again happening in this region,” Ragan Dickens with the Louisiana Oil and Gas Association told the Associated Press, “it’s easy for opposition or the other side of the argument to pinpoint to hydraulic fracturing or waste water disposal. But the fact of the matter is these earthquakes have been going on for well over 100 years.”

"Injection is probably one of the two leading causes of induced seismicity that we know of around the world already,” said Dr. Don Van Nieuwenhuise, Director of Professional Geoscience Programs at the University of Houston.

Adding fuel to the argument this week is a two-year study of the Eagle Ford Shale formation in southwest Texas that suggests that the sheer volume of oil production activity is triggering earthquakes in the area.

"These associations between seismic activity and increases in injection/production volumes imply that many of the Eagle Ford earthquakes were triggered/induced,” the report states. “Of course, injection/production activity is nearly ubiquitous throughout much of the Eagle Ford, and in many areas this activity increased markedly in 2010. Thus it is possible that earthquakes of natural origin may occur coincidentally near active wells. However, the observation that most earthquakes identified in this study occurred during the second year of the survey, when regional injection/production rates were generally higher, favors an induced/triggered origin."