What accounts for this?
On Tuesday, scientists from Southern Methodist University added to the growing body of research linking small earthquakes to oil and gas wastewater disposal. That body of research is particularly important to the popular but controversial process of hydraulic fracturing, or fracking, which produces significantly more wastewater than conventional drilling.
The research published by SMU scientists links a series of small earthquakes in Azle, Texas to oil and gas activity — specifically, the process of injecting drilling wastewater underground. According to the research, the faults that shifted below Dallas-Fort Worth “have not budged in hundreds of millions of years.”
Like other research, the SMU study doesn’t definitively say that wastewater injections caused the quakes. It just says that they’re the most likely explanation.
What makes the Texas study a bit different than other research linking human activity to seismic events is that it suspects wastewater injection alone is not causing the quakes. Instead, it asserts that there’s a specific thing workers do when extracting fuel and performing wastewater injection that may be triggering them.
According to the research, quakes may be made more likely when workers extract gas and groundwater from one side of a fault line, then inject water back into the ground on the other side of the fault. That is slightly different than what other research has suggested — that wastewater injected anywhere near fault lines can change the stress of those faults to the point of failure, causing earthquakes.
Still, the basic idea is the same: human activity, via oil and gas watewater injection, is the most likely explanation for these unusual strings of earthquakes happening across the country.
“It’s what we figured all along, it’s not really new news to us,” said Azle Mayor Alan Brundrett, according to NBC’s Dallas affiliate. “It’s just confirming our suspicious that we’ve had.”
The fact that scientists haven’t been able to make definitive statements about oil and gas activity’s connection to earthquakes has been the main argument of industry supporters when these issues arise in states, particularly Texas and Oklahoma. The Texas Railroad Commission, which regulates oil and gas activity, has been resistant to concerns that fracking activity may be causing quakes in the state. In response to Tuesday’s study, the agency’s staff seismologist Craig Pearson said it “raises many questions with regard to its methodology,” but declined to say exactly what those questions were before meeting with the researchers.
In Oklahoma, which is now seeing anywhere from two to 20 small earthquakes every day, state officials have been extremely reluctant to say drilling is the cause. That is, until Tuesday.