A process that involves injecting powerful blasts of water, sand and chemicals into the ground to release natural gas may be responsible for a major uptick in the number of earthquakes in Canada, according to two new studies.
Hydraulic fracturing, also known as fracking, was the subject of two independent papers released this week.
The studies, one from the U.S. and another from Britain, both suggested that the fracking process is directly linked to an increase in the number of low-magnitude tremors.
Conclusive studies have not yet been done in Canada, where fracking is primarily used in northeast B.C.
John Cassidy, a seismologist with Natural Resources Canada, told CTV's Canada AM the studies are in the "early days" and "we're talking small earthquakes and small numbers of earthquakes."
He added: "There's no evidence at this point of large or damaging earthquakes associated with this process."
Each year in B.C., Cassidy said, Natural Resources tracks about 2,000 earthquakes. In the northeast corner, where fracking is employed most intensely, there were 31 tremors over a three-year period in the magnitude of 2 to 3.5.
"So these are very tiny earthquakes that weren't felt, in fact," he said.
To put it in context, Cassidy said there are roughly 130,000 magnitude-3 earthquakes each year around the world, and most of them go unnoticed by the general public.
However, federal and provincial agencies aren't dismissing concerns about the seismic impact from fracking.
Natural Resources Canada launched its own study on April 1, seeking to determine whether fracking is leading to an increased number of quakes in B.C., New Brunswick and Quebec, where the process is used to extract natural gas.
And B.C. is in the midst of a similar study in the northeast corner of the province where most of the fracking activity is taking place.
Cassidy said the goal is to find out whether there is a connection between fracking and earthquakes.
"Are (earthquakes) linked with this process, and if they are they are attributed to the injection fluids? Is it attributed to local geology, to the local stress field, to the type of rock or the volume of water being pumped in? If there are links, what are the links and how can we better assess that?" he asked.
Andrew Miall, a geology professor at the University of Toronto, said most of the quakes cited in the two studies would typically go unnoticed, but are being picked up now due to the increased scrutiny of the industry.
"It's extremely unlikely, not of course impossible, but extremely unlikely that there would ever be an earthquake strong enough, say (magnitude) three or four, that would start to seriously shake or rattle buildings and do some damage. The probability is very low," Miall told Canada AM.
He acknowledged there is the "very remote" possibility that a natural gas well located close to a major fault line could trigger seismic stress of a larger scale, but said the greater concern is the environmental impact from fracking.
"A much more serious issue is the possibility of leakage of fracking fluids and methane into groundwater wells and that is a problem that has emerged in places like Pennsylvania and that is a problem that needs to be dealt with through proper management and regulation of the industry," Miall said.
