The Seismological Society of America (SSA) has said in a new report that fracking can induce stress in existing faults tens of miles away from the fracking site. The injection of pressurized water puts stress on pre-existing faults and can cause them to rupture triggering earthquakes.
“It is important to avoid inducing earthquakes large enough to be felt, that is, earthquakes with magnitudes of about 2.5, or greater, because these are the ones that are of concern to the public,” said Art McGarr, a geophysicist with USGS.
A press briefing issued to eurekalert.org stresses that man-made quakes need to be included in seismic hazard planning.
The number of earthquakes within central and eastern United States has increased dramatically over the past few years, coinciding with increased hydraulic fracturing of horizontally drilled wells, and the injection of wastewater in deep disposal wells in many locations, including Colorado, Oklahoma, Texas, Arkansas and Ohio. According to the U.S. Geological Survey (USGS), an average rate of 100 earthquakes per year above a magnitude 3.0 occurred in the three years from 2010-2012, compared with an average rate of 21 events per year observed from 1967-2000.
This is a five-fold increase in the number of quakes in the area. This could have major implications for wells that lie along larger faults such as the New Madrid Fault that runs some 130 miles from Cairo, Illinois to Marked Tree, Arkansas. A major quake on the New Madrid could displace up to 7 million people according to FEMA.
Geologists in Ohio have been reporting that earthquake activity has increased in and around the areas where fracking occurs prompting AP to report:
Geologists in Ohio have for the first time linked earthquakes in a geologic formation deep under the Appalachians to hydraulic fracturing, leading the state to issue new permit conditions Friday in certain areas that are among the nation’s strictest.
A state investigation of five small tremors last month in the Youngstown area, in the Appalachian foothills, found the injection of sand and water that accompanies hydraulic fracturing, or fracking, in the Utica Shale may have increased pressure on a small, unknown fault, said State Oil & Gas Chief Rick Simmers. He called the link “probable.”
While earlier studies had linked earthquakes in the same region to deep-injection wells used for disposal of fracking wastewater, this marks the first time tremors in the region have been tied directly to fracking, Simmers said. The five seismic events in March couldn’t be easily felt by people.
Glenda Besana-Ostman, a former seismologist with the Ohio Department of Natural Resources, confirmed the finding is the first in the area to suggest a connection between the quakes and fracking. A deep-injection wastewater well in the same region of Ohio was found to be the likely cause of a series of quakes in 2012.
With an increase in fracking sites across the country we have to face the fact that more and more earthquakes are likely to occur. The proximity of fracking sites to known faultlines needs to be more closely scrutinized if the triggering of larger events is to be avoided. This is the opinion of Gail Atkinson, professor of earth sciences at Western University in Ontario, Canada. She addressed the SSA saying:
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“I think ultimately, as fluids propagate and cover a larger space, the likelihood that it could find a larger fault and generate larger seismic events goes up,”
There’s a very large gap on policy here,we need extensive databases on the wells that induce seismicity and the ones that don’t.”