HOUSTON, Aug. 7 (UPI) -- There might be a link between seismic activity and fracking for oil and gas, a research study published this week indicates.
The two-year inquiry by the University of Texas at Austin found that most recent earthquakes in North Texas happened close to injection wells that dispose of wastewater used in the fracking process, The Houston Chronicle reported.
The study also found that relatively minor earthquakes are happening more often than indicated in previous studies.
Lead researcher Cliff Frohlich said you can't prove that any one earthquake was caused by an injection well.
"But it's obvious that wells are enhancing the probability that earthquakes will occur," he said.
A U.S. Geological Survey report released earlier this year found that an increase in small temblors throughout the Midwest coincides with the injection of drilling wastewater in deep disposal wells.
Drilling companies have said they do not believe earthquakes are linked to injection wells.