Researchers in Texas have found conclusive evidence that hydraulic fracturing (fracking), a controversial process used to extract tough to reach oil and gas, causes earthquakes it was reported Tuesday.
A seismology team led by SMU believes it's found a cause for the ones earthquakes that hit Azle, Texas a couple of years ago.
"Causal Factors for Seismicity near Azle, Texas" was published in the jounral Nature Communications. A press release about the findings of the study was also released on Tuesday.
Fracking involves pumping water and chemicals into the ground in large volumes so that petroleum liquids below it rise to the surface and can be easily extracted.
The team's research states that "high volumes of wastewater injection combined with saltwater (brine) extraction from natural gas wells is the most likely cause of earthquakes."
Oil and gas drilling takes water out of the ground as a byproduct of energy production. That same water is pumped back into the ground in wastewater injection wells. The SMU geologists measured those activities, centered around the Newark East Gas Field north and east of Azle.
The team discovered 70 energy-producing wells in the field, and two adjacent wastewater injection wells. When the levels of water injection and withdrawal increased so did the incidence of earthquakes, the report says.
The quakes they studied hit Azle between late 2013 and the spring of 2014, where seven quakes of magnitude 3.0 or higher were reported. The team developed a 3D model to investigate two intersecting faults and estimate stress changes.
The injection and withdrawal wells were near two faults. The combination of factors, initiated by the oil and gas water activity, likely produced the quakes, said Dr. Matthew Hornbach, an SMU geologist.
Their findings add to the controversy around the practice. Fracking has bee banned in numerous counties and states, including New York and many counties in California.