Oil and gas commission investigating quakes in northeast British Columbia

A natural gas plant is pictured outside of Fort St. John, B.C., Thursday, Oct. 11, 2018. (THE CANADIAN PRESS Jonathan Hayward)

FORT ST. JOHN, B.C. -- The British Columbia Oil and Gas Commission is investigating a series of earthquakes that one expert says were very likely caused by hydraulic fracturing, a fuel extraction process also known as fracking.

Earthquakes Canada reported a 4.5 magnitude quake just before 5:30 p.m. Thursday that was felt in Fort St. John, Taylor, Chetwynd and Dawson Creek in the province's northeast. A second quake rattled the region about 45 minutes later and measured 4.0.

The oil and gas commission issued a brief statement Friday that said operations in the area were immediately shut down as a precaution and mitigation strategies will be put into place for any operations linked to seismic events.

Honn Kao, a research scientist with the Geological Survey of Canada, said the probability is "very high" that the tremors were caused by fracking, which involves injecting high-pressure liquid into the ground to extract oil and gas.

He said the survey established seismic stations in the region in 2013 and the stations automatically detected the quakes Thursday evening. It contacted the oil and gas commission, which investigated to see if there is a specific fracking operation nearby, he said.

"Our colleagues at the BC Oil and Gas Commission immediately realized that there was an active hydraulic fracturing operation in the vicinity of the epicentre," he said.

He said the quakes are consistent with the pattern of fracking-induced events, and the preliminary assessment of the geological survey is that the tremors were likely caused by fracking. The geological survey and the oil and gas commission continue to investigate, he said.

"This is not 100 per cent proof ... but we are continuing to work with the BC Oil and Gas Commission to get more detailed operation data."

Geoff Morrison, B.C. manager of the Canadian Association of Petroleum Producers, said safe and sustainable natural gas development is a priority for operators in northeast B.C.

"Natural gas activity is strictly regulated and monitored, and the safety of communities located near operations is of paramount importance. We have a track record of robust regulations, employing best industry operating practices, and working to continuously improve our environmental performance," he said in a statement.

The industry will continue to work closely with the oil and gas commission as it conducts its investigation, he added.

The commission has been monitoring induced seismicity caused by fuel extraction activities for some time. It has previously found that hydraulic fracturing and wastewater disposal can cause seismic activity.

It released two studies on induced seismicity caused by oil and gas activities, in 2012 and 2014. The most recent study found there were 231 seismic events caused by oil and gas operations in the Montney Trend, a natural gas reserve in northeast B.C., between August 2013 and October 2014.

The U.S. Geological Survey said in its tectonic summary of Thursday's quake in northeast B.C. that there is evidence that some North American earthquakes have been triggered by human activities that have altered the stress conditions in the Earth's crust, including fracking.

Kao said the majority of fracking does not induce earthquakes that are felt by people.

One of the reasons that fracking can cause earthquakes that are felt is because the water or fluids injected into the ground disturb naturally occurring geological faults.

In Canada, the highest recorded magnitudes of earthquakes caused by fracking are about 4.5 to 4.6, Kao said, adding that the duration of these earthquakes is short and they are usually shallow.

"Even though the preliminary assessment appears to indicate that this is an induced event, we are still working on it and making sure our analysis is as complete as possible."

By Hina Alam and Laura Kane in Vancouver