DisastersTexas wants to know whether fracking causes earthquakes

In response to the several minor earthquakes which occurred in late 2013 around the Azle, Texas area, local officials are investigating whether oil and gas drilling in North Texas and the injection wells that follow after, are responsible for the quakes.

Texas has about 35,000 active injection wells, according to the Texas Railroad Commission. Injecting water into an empty ground formation is unlikely the cause of a seismic event. The Star-Telegram reports, however, that about 7,000 of Texas’s injection wells are used for disposing wastewater deep underground, and some experts say these wells can cause earthquakes.

“In a way, Texas has been a vast experiment in injection wells,” many of which are used to dispose of oil field waste, said seismologist Cliff Frohlich, associate director of the Institute for Geophysics at the University of Texas at Austin. Disposal wells do not typically create seismic events but they could, according to Frohlich. A 2012 study by Frohlich discovered that “injection-triggered earthquakes are more common than is generally recognized.”

There are five active disposal wells in northern Parker County and southern Wise County, where more than twenty earthquakes occurred in November and December of 2013. Complaints from county residents have prompted the Railroad Commission to hire an in-house seismologist to investigate the matter.

Faults inside the Earth, typically formed millions of years ago, could be responsible for causing injection wells to trigger earthquakes. Faults are not always identified before drilling takes place and even when identified, it is uncertain whether faults will produce an earthquake if an injection well is drilled nearby.

Yet, Ken Morgan, director of the TCU Energy Institute, insists that “there are better places and worse places for disposal wells. That is common sense. If you have faults and a cluster of quakes, you’ve rounded up some suspects” by looking at nearby injection wells.

Experts agree that identifying a single injection well as the cause of a particular earthquake is difficult, but a surge of regular seismic events similar to those that occurred in Azle is grounds for suspicion. “Evidence would be if earthquakes started not too long after an injection well began operation,” said Art McGarr, an earthquake researcher at the Geological Survey. “If they started within one or two months, that’s pretty good evidence. Even better evidence is if injection is stopped and the earthquakes stop.”

Scientist have in the past controlled earthquakes by starting and stopping underground fluid injection, according to Morgan.

Fort Worth lawyer Jim Bradbury, who is familiar with environmental issues of energy production, has suggested that Texas regulators should adopt a standard proposed by the U.S. Geological Survey called the traffic light system. If earthquakes above a certain magnitude occur near a disposal well, it would receive a yellow light, requiring a reduction in the amount of waste it is injecting. If seismicity continued or escalated, the well would receive a red light, and operations could be suspended.