By Tom Kenworthy
Scientists from two Texas universities are looking into a pair of recent earthquakes near the Texas-Louisiana border for clues to whether they were related to underground injection of oil and gas drilling waste produced in the course of hydraulic fracturing or fracking.
One of the scientists studying the two recent Texas quakes was on a team that concluded a swarm of earthquakes near Dallas in 2008 and 2009 were related to the disposal of drilling wastes, according to E&E’s Energy Wire.
Cliff Frohlich, a research scientist at the University of Texas who studied those Dallas area quakes, did not rule out a similar conclusion in the recent east Texas quakes.
“It’s possible they were natural,” he said. “It’s possible they were man-made.”
The two quakes, a 3.9 magnitude event on May 10 and a 4.3 magnitude one on May 17, took place northeast of Nacogdoches, Texas. That area is part of the Haynesville shale formation and is home to injection wells.
The two recent events come about a month after the US. Geological Survey reported that a big increase in earthquakes across a large part of the nation’s midsection since 2001 is “almost certainly manmade.” Though the agency did not tie the increase directly to a big increase in drilling for gas and oil from shale formations, it did say the surge in seismic activity “corresponds” to that development and the huge jump in fracking and the underground disposal of liquid wastes that flow back to the surface after fracking jobs are completed. Fracking involves the injection at high pressure of large quantities of water, sand and chemicals into underground rock formations to release oil and gas. Afterwards, much of that mixture, commonly called brine, is brought back to the surface and often disposed of by re-injecting it deep underground.
In March, Ohio oil and gas regulators linked a dozen earthquakes in the northeast part of the state to the disposal of drilling brine after hydraulic fracturing. At the same time, the state announced new regulations governing the transport and disposal of drilling wastes, including banning underground injections into a formation that contains a fault in the region.
Tom Kenworthy is a Senior Fellow at the Center for American Progress.