Researchers shared their findings at the Seismological Society of America 2019 Annual Meeting. They identified more than 600 earthquakes in states like Ohio, Texas, Pennsylvania, Oklahoma and West Virginia that were linked to the practice, ranging in magnitude from 2.0 to 3.8.
Michael Brudzinski of Miami University of Ohio said that the earthquakes caused directly by fracking are “underappreciated” when compared to those linked to wastewater disposal because they happen less frequently. However, they should not be underestimated as they pose a real threat.
Fracking, or hydraulic fracturing, sees pressurized liquids being used to create cracks in rock formations through which natural gas and petroleum can flow to facilitate extraction. This process causes earthquakes to occur that are usually so tiny they cannot be detected without instrumentation.
Many times, the resultant wastewater is then injected back into the layers of rock. This increases the pore pressure in the rock and can stress fault lines, triggering even more earthquakes. These earthquakes are often larger as the fluid pressure moves away from the well toward deeper faults.
Some areas in the Appalachian Basin have seen a sharp increase in the production of natural gas in the last few decades, and it’s not surprising that there is increased seismic activity there.
The scientists used multi-station template matching for their study. This technique scans through seismic signals in search of those that match the “fingerprints” of known earthquakes. They were able to highlight smaller earthquakes that might have been overlooked which enabled the researchers to compare them with the region’s earthquake catalog so they could match up the timings and locations with fracking operations in the area.
Although location and timing are the main criteria used to identify earthquakes that were caused by fracking, researchers say that seismic activity related to fracking itself generally looks different from that linked to wastewater disposal. It’s marked by bursts of seismicity that can number in the thousands over a short period of time. They’ve identified two factors as having a strong link to fracking-induced seismicity: the depth of the well and overpressuring.
Those who profit from fracking often claim that wastewater disposal is the only source of man-made earthquakes associated with the process, but this and other research shows that is simply not true.
Rises seen in Pennsylvania and Ohio
Pennsylvania, which was not prone to seismic activity in the past, has seen a sharp rise in activity thanks to fracking operations in the area. In April 2016, for example, at least five small earthquakes were registered in Lawrence County, all of them with epicenters within a five-mile radius of a gas well pad. At the time of the earthquakes, the Hilcorp Energy Company had been using a technique known as “zipper fracturing” that sees two parallel wells drilled simultaneously.
In Poland Township, Ohio, 77 earthquakes were reported in 2014 with magnitudes as high as 3.0 in the area around two wells used by the same company for fracking. One of the quakes was believed to be one of the biggest earthquakes ever produced by fracking, and it was strong enough to be felt by local residents.
Earthquakes are really only part of the story when it comes to fracking complications. The practice is also contaminating drinking water with carcinogens through wastewater injection, not to mention air pollution. Our planet is being destroyed and its basic structure is being disrupted, all in pursuit of the almighty dollar.
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