B.C.'s Oil and Gas Commission confirmed the cause of the earthquake in an email statement to CBC this week, saying it was "triggered by fluid injection during hydraulic fracturing."
The 4.4-magnitude quake was felt in Fort St. John and Fort Nelson in August 2014. It was preceded by a 3.8-magnitude earthquake in late July, also caused by fracking.
B.C.'s Oil and Gas Commission told CBC that several companies were doing hydraulic fracturing in the area at the time, and several more were disposing of fracking waste.
But the commission says it was Progress Energy's operations that were "associated with triggering this event."
Hydraulic fracturing, often called fracking, is the process of injecting water, sand and chemicals at high pressure deep underground to break rock and free gas.
Since the 2014 earthquake, Progress Energy has been ordered to reduce the volume of fracking fluid being used, and the company has complied, according to the commission.
As well, new seismic equipment has been set up in the area. No new earthquakes have been detected in the immediate area.
Sign of things to come?
Progress Energy is owned by Petronas of Malaysia, which also owns Pacific NorthWest LNG, the firm planning to build a giant liquefied natural gas export facility near Prince Rupert, B.C. supplied by gas fracked in northeastern B.C.
Matt Horn, with clean energy advocate the Pembina Institute, calls the significant earthquake "another warning sign for what could be down the road.
"If B.C. goes down the LNG road in a big way, it's really important when we're debating LNG proposals, we're eyes wide open.... to both the benefits and impacts. Increased earthquakes is one of those impacts."
B.C.'s Oil and Gas Commission declined a taped interview, providing only background information by email.
B.C. Minister of Natural Gas Development Rich Coleman and Peace MLAs Mike Bernier and Pat Pimm didn't respond to requests for comment.
Progress Energy did not respond to a request for comment by deadline.
In January, Alberta's energy regulator reported fracking likely caused a 4.4-magnitude earthquake in the northern town of Fox Creek. Scientists told CBC at the time the quake was the largest in the world ever caused by fracking.
Last week, Progress Energy temporarily shut down another fracking site, after a 4.6-magnitude earthquake hit just three kilometres away. Officials say it will take several more weeks to determine if that quake was triggered by fracking.
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