The British Columbia Oil and Gas Commission has confirmed that a 4.6 magnitude earthquake that occurred in northeast British Columbia on August 17, 2015 was caused by fluid injection during hydraulic fracturing or "fracking".
The earthquake, according to B.C. Oil and Gas Commission, which regulates the B.C. oil and gas industry, may be the biggest seismic event ever recorded in the province and the largest fracking-caused earthquake in history.
The B.C. Oil and Gas Commission confirmed in a statement released earlier this week that the 4.6 magnitude earthquake "was caused by fluid injection during hydraulic fracturing from an operator in the area."
The commission noted that the epicenter of the earthquake, about 110 kilometers northwest of Fort St. John in British Columbia, was only about three kilometers from a fracking site operated by Progress Energy Canada Ltd.
According to the Globe and Mail, company workers at the site reported that their trucks shook and power poles swayed during the quake, forcing the company to suspend operations at the site.
The latest fracking-induced quake surpassed another reported last year in B.C. It also surpassed two 4.4 magnitude earthquakes reported in Alberta last year.
Honn Kao, a researcher with Geological Survey of Canada, stated that if the latest quake was caused by fracking, then it was the largest fracking-induced earthquake ever recorded.
Although the increasing evidence that fracking is able to induce significant seismic activity is causing concern to operators, regulators, and members of the public, Dr. John Cassidy, a seismologist with the Geological Survey of Canada, said most of the earthquakes were small and thus not of immediate public safety concern.
But he acknowledged that the pattern of earthquakes triggered by fracking was increasing in frequency and magnitude.
"The overall pattern is that there's an increase in the number of induced earthquakes," he said, "and there is an overall or average increase in the magnitude as well."
A previous study by Cassidy had noted there were only 24 earthquakes in northeast B.C. in 2002-2003 before fracking operations started in the area. However, in 2010-2011, after fracking activity in the Horn River Basin of northeast B.C. had peaked, there were 189 earthquakes.
Experts have noted that the pattern of dramatic increase in frequency of earthquakes in northeast B.C. following introduction of fracking operations has also been observed in the United States. Since 2009, when fracking operations began in Oklahoma, an average of two earthquakes a day have been reported compared with only two or three earthquakes a year before fracking operations became widespread.But fracking is not believed to be the direct cause of earthquakes in Oklahoma. The earthquakes are believed to be caused by fracking-related activity that involves injecting huge volumes of waste water from fracking operations into underground wells.
"The majority of recent earthquakes in central and north-central Oklahoma are very likely triggered by the injection of produced water in disposal wells," according to the Oklahoma Geological Survey.
Hydraulic fracturing or "fracking" involves injecting a mixture of water and chemicals into the ground at high pressure to fracture shale and release otherwise inaccessible oil and gas.
"The majority of recent earthquakes in central and north-central Oklahoma are very likely triggered by the injection of produced water in disposal wells.""What we're finding is with the hydraulic fracturing, we are seeing an increase in the number of induced earthquakes," Cassidy said. "These are almost all tiny, tiny earthquakes, however. They are not associated with all wells, in fact, it's a very small fraction of the wells that show induced earthquakes."
Recent studies show that most fracking-induced quakes are shallow, but trigger relatively strong shaking.
Ken Paulson, chief operating officer of the B.C. Oil and Gas Commission, said that Progress Energy Canada Ltd., the company whose operations allegedly triggered the earthquake, followed regulations and stopped operations as soon as the quake was recorded.
B.C. and Alberta regulations require that operators suspend operation and consider how to mitigate the effect of their operations following any seismic event of 4.0 magnitude or greater.
"We allowed them to continue operations with a reduced pump rate," Paulson said, "but if another event were to occur of 3.5 or greater, you have to shut it down again and we'll try something different."
According to Paulson, no further significant earthquakes occurred after the pump rate was reduced.
A spokesperson for Progress Energy, said, "We take this incident very seriously. We will continue to be diligent and monitor our activities and adjust our operations as needed, such as decreasing fluid volume and pressure."
[Photo By Brennan Linsley/AP]