A new study by researchers at the U.S. Geological Survey (USGS) projects the number of people living in areas of “significant” risk of human-induced seismic activity, defined as areas with a 1–12 percent chance of human-caused seismic activity, decreased by 50 percent compared to 2016.
This decline is especially evident in areas where wastewater injection from oil and gas fracking operations is taking place.
The study, published in Seismological Research Letters, found the number of people living in areas of significant risk from manmade earthquakes has decreased from seven million to 3.5 million people. Researchers found the declines occurred in five focus areas: Oklahoma-Kansas, New Mexico, North Arkansas, North Texas, the Raton Basin on the border of Colorado, and the New Madrid Seismic Zone in Illinois and Tennessee.
In Oklahoma, USGS found reduced wastewater injection volumes in disposal wells in the state, among other precautions taken to lessen risk factors for manmade seismic activity, were responsible for the steep decline.
Tim Benson, a policy analyst at The Heartland Institute, which publishes Environment & Climate News, says the newest USGS study confirms the findings of previous academic and federal and state government research: Seismic events from wastewater injection wells have always been rare. Even before the recent decline, the power of such seismic events was also small and produced limited damage.
“The USGS report makes clear that what was already not a serious problem has become even less of one due to the sensible precautions drillers have taken with injection wells,” Benson said. “Seismicity concerns about fracking have never been scientifically justified, and concerns about injection wells are being proven totally overblown.”
Gary L. Stone, vice president of engineering for Five States Energy Capital, says the study validates claims injection wells rarely contribute to seismic activity and steps taken to reduce earthquakes are working.
“The recent research did a good job describing the risks and facts of seismic activity from injection wells,” said Stone. “Your real test ground is Oklahoma, because when you look at the history of seismicity, it went from very small and infrequent to somewhat larger and more frequent occurrences during the 2008–14 drilling period.
“As they implemented new procedures, particularly the shutting in of injection wells, earthquake trends significantly declined both in frequency and intensity,” Stone said. “Logically, that is what you’d expect. The real problem was never fracking itself, but rather the disposal wells injecting deep into the Arbuckle [rock formation], deep into the basement rock.”
Michael McGrady ([email protected]) writes from Colorado Springs, Colorado.
Mark D. Petersen et al., “2017 One‐Year Seismic‐Hazard Forecast for the Central and Eastern United States from Induced and Natural Earthquakes,” Seismological Research Letters, March 1, 2017: http://srl.geoscienceworld.org/content/early/2017/02/24/0220170005