LONDON, Ontario, March 29 (UPI) -- New research suggests hydraulic fracturing, or fracking, is inducing earthquakes in Western Canada.
Though alarming, the correlation isn't new. Several studies have linked gas and oil operations in the Plains states to a rise in the frequency of earthquakes.
Scientists in the United States have mostly blamed the earthquakes on the injection of wastewater back into the ground after the recovery of oil and gas. In Canada, researchers say the fracking process shoulders most of the blame.
Researchers with the Seismological Society of America identified the link by analyzing the temporal and geographical proximity of earthquakes to fracking and wastewater disposal activity.
They determined that only 5 to 10 percent of the earthquakes measured in Western Canada are caused by natural tectonic shifts. Human activity is to blame for the rest -- 60 percent of the quakes were linked to fracking, while 30 to 35 percent were linked with wastewater wells.
Scientists aren't sure why wastewater plays a bigger role in triggering earthquakes in the United States. Many operations in Oklahoma, Texas, the Dakotas and elsewhere use more water than operations in Canada. It may also be that the seismic effects of wastewater disposal are hiding a link between fracking and earthquakes.
"We're not entirely sure that there isn't more seismicity in the central U.S. from hydraulic fracturing than is widely recognized," Gail M. Atkinson of Western University said in a news release.
The findings -- published in the journal Seismological Research Letters -- failed to reveal a link between fluid volume and earthquake magnitude.
"It had previously been believed that hydraulic fracturing couldn't trigger larger earthquakes because the fluid volumes were so small compared to that of a disposal well," Atkinson explained. "But if there isn't any relationship between the maximum magnitude and the fluid disposal, then potentially one could trigger larger events if the fluid pressures find their way to a suitably stressed fault."
Atkinson and her colleagues are now trying to examine how various types of fracking techniques and fault structures might affect the link between fracking and seismic activity.