Research ties unstable bedrock to quakes set off by fracking
New research is digging into why fracking causes earthquakes in some areas but not in others.
A paper published Monday in Geophysical Research Letters suggests the likelihood of an artificial earthquake is heavily influenced by how stable the ground was before fracking begins.
“Some places appear to be particularly responsive ... while other places aren’t,” said Honn Kao, a seismologist with the Geological Survey of Canada and lead author.
Scientists have known for some time that injecting fluids to dispose of waste water or to free underground reserves of oil and gas can cause earthquakes.
Regulatory records show there have been hundreds of seismic events since 2015 in a heavily fracked area of northwestern Alberta. Those earthquakes around the Fox Creek area have registered as high as 4.5 on the Richter scale — strong enough to rattle dishes and pictures. Alberta’s energy regulator has tightened restrictions on fracking in the area.
Meanwhile, other regions see thousands of wells fracked while the earth remains still.
While the link between fracking and earthquakes is well-established, precisely how that link works remains mysterious.
Other studies have asked if it’s related to local geology or particular fracking practices, but Kao said he’s found a much more important contributor.
“The background tectonic loading rates appear to be one of the predominant factors that control the region’s response to injection induced earthquakes,” he said.
In other words, the deep, underground shifting of Earth’s rocky tectonic plates create zones where tension is concentrated and stored like a coiled spring, called tectonic deformation. The sudden shattering of rock through fracking or the injection of high-pressure waste water releases that pent-up energy in the form of an earthquake.
The finding could help explain why western Alberta and northeast B.C. have a high rate of fracking-induced earthquakes and places such as Saskatchewan, which has thousands of fracked wells, doesn’t.