A recent swarm of modest earthquakes in the Irving, TX, area drew a substantial amount of media attention, and much of it pointed a finger at Barnett Shale drilling activities such as hydraulic fracturing and the injection of drilling waste into disposal wells. It's too soon to lay any blame, said a seismologist writing in the Dallas Morning News.
"Let's begin with what we know: there have been 18 earthquakes with magnitudes greater than 2.5 up to magnitude 3.6 in and around Irving since November 2014," wrote Railroad Commission of Texas (RRC) staff seismologist Craig Pearson in a recent editorial. "Understandably, residents of the region want to know what's causing them, and whether there is anything possible that can be done to stop or reduce seismic activity."
Pearson said "speculation has run rampant" that the seismic activity is related to oil/gas operations, but there is no evidence to support the assertion based on his research along with scientists at Southern Methodist University (SMU).
"There are two [natural] gas wells just north of the estimated epicenters of earthquakes in Irving; both wells are inactive," Pearson said. "One of those wells never produced and the other has not been operational since 2013. The nearest active disposal well is more than 10 miles away in Tarrant County.
"Following a 3.6 earthquake in Irving on Tuesday, Jan. 6, 2015, the commission dispatched inspectors to both inactive wells and the disposal well to check for any possible damage. None was found. The commission is also requesting daily pressure reports from the Tarrant Co. disposal well operator."
Pearson wrote that other earthquake swarms elsewhere in North Texas have "...dissipated almost as quickly as they began." None has been powerful enough to cause "...even nominal damage," he said.
"I will continue to work closely with SMU researchers and review any information that could help determine the precise location and cause of recent seismic activity in Irving."
Seismic activity in the Barnett Shale region has been stirring fears among area residents for some time, and drilling activities are usually the first thing that they suspect. The RRC hired Pearson last March (see Shale Daily, March 28, 2014) to help get to the bottom of the quaking after a raucous meeting at the RRC where commissioners heard from numerous angry citizens (see Shale Daily, Jan. 21, 2014).