Irving-area quakes are likely due to fault lines, geologist says

A seismograph records earthquake activity
A seismograph records earthquake activity Getty Images/iStockphoto

The frequent but mild earthquakes giving shivers to the Irving area — but not other areas in North Texas — likely should be blamed on geologic fault lines rather than gas drilling practices, a geologist said Tuesday.

“Based on known geology and known science, the most likely explanation is that it’s occurring in a known faulted zone of an old buried mountain range,” Craig Pollard, vice president of exploration for Cinco Resources, said after a presentation hosted by the Institute for Policy Innovation.

IPI is an nonprofit pro-economic-growth organization that has been fighting municipal efforts to restrict drilling and fracking.

The correct message hasn’t been getting out, Pollard said during his 90-minute speech and discussion to an audience of about 50 people, including many geologists.

“The media is working on sensationalism,” Pollard said. “For it not to be water injection, for it not to be fracking, is not news.”

But he said the different formations west of the Metroplex, including Cleburne and other Johnson County communities, point more toward wastewater injections into old wells than to fracking, the technique of high-pressure pumping of water and chemicals to crack shale and release its oil or gas.

He noted that Dallas sits on an ancient mountain range buried in sediment from the Cretaceous period, which ended 66 million years ago along with the dinosaurs. Mountains, because of the way they’re formed, indicate a web of fault lines. Tarrant County sits on a flat formation, indicating few faults.

But he said the culpability of wastewater or saltwater injections is limited because of underground pressure that resists the water. Pumping power is the key.

“Three miles is the farthest anybody has done scientific experiments to determine how far water can be pumped away from a well,” he said.

Irving has been near the epicenters of many recent quakes. A 3.3-magnitude earthquake hit northwest Dallas on Monday afternoon, the latest of more than 50 in the past 18 months.

The earthquake occurred at 1:14 p.m. Its epicenter was 4 miles north of Irving and 5 miles southwest of Farmers Branch, according to the U.S. Geological Survey.

The largest earthquake, which measured 4.0-magnitude, led the Texas Railroad Commission to send in a team of inspectors. The agency, which regulates the oil and gas industry, also asked the operators of five disposal wells in the area to run pressure tests. Scientific studies have linked oil and gas operations to a string of earthquakes near Reno and Azle.

Ramona Nye, a spokeswoman for the state agency, said tests on the wells in Johnson County are still being conducted, but since there are no disposal wells in Dallas County, there are no plans to dispatch inspectors to the area of Monday’s quake.

This report includes material from the Star-Telegram archives.

Robert Cadwallader, 817-390-7641

Twitter: @Kaddmann_ST

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