A hydraulic fracturing operation near Fox Creek, Alta., has been shut down after an earthquake hit the area Tuesday.

The magnitude 4.8 quake was reported at 11:27 a.m., says Alberta Energy Regulator, which ordered the shutdown of the Repsol Oil & Gas site 35 kilometres north of Fox Creek.

Carrie Rosa, spokeswoman for the regulator, says "the company has ceased operations … and they will not be allowed to resume operations until we have approved their plans."

Rosa added the company is working with the energy regulator to ensure all environmental and safety rules are followed.

In a statement, Repsol confirmed the seismic event and said the company was conducting hydraulic fracturing operations at the time it happened.

"Repsol immediately shut down operations and reported the event to the AER and other local authorities," the statement said.

"The company is investigating the event, which includes reviewing and analyzing available geological and geophysical data, as well as the onsite seismic monitoring data. Operations will not resume at this location until a full assessment of the event has been completed and approval has been received from the AER."

There were no reports of injuries or damage to the site, Rosa said.

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An earthquake with a magnitude of 4.8 hit the Fox Creek area Tuesday morning, prompting the closure of a fracking operation. (The Tyee )

The energy regulator automatically shuts down a fracking site when an earthquake hits a magnitude of 4.0 or higher in the area in which a company is operating.

"It's too soon to tell if it's related to fracking," said Camille Brillon, a seismologist with Natural Resources Canada. "It was a light earthquake that would have been felt."

Earthquake 'larger than normal'

Brillon added the quake was "quite large for the area, larger than normal." It was so strong that it was felt in St. Albert, 280 km away.  

Jeffrey Gu, associate professor of geophysics at the University of Alberta, said the area surrounding Fox Creek has been experiencing a proliferation of quakes lately.

He estimates in the last six months there have been hundreds of quakes in the area ranging in magnitude from 2.0 to 3.0.

But it is not considered a risky area with a such low population, said Gu, who added that Fox Creek and the surrounding region is carefully monitored by the energy regulator.

"There are faults in this area that have been mapped, have been reported in that area, but nothing of significance," he said.

"It's a relatively safe area without major, major faults."

Still, Gu said, there were two fairly large quakes in the area in January 2015, one of which had a magnitude of 4.4.

He wasn't able to confirm that they were caused by fracking, but said it is "highly probable."

The energy regulator said at the time that the 4.4 magnitude quake was likely caused by hydraulic fracturing.

The previous large quake near Fox Creek occurred on June 13, with a magnitude initially measured as 4.4. And that was the first time AER issued a stop-order on fracking under its new rules, which came into effect in February. After some investigation the magnitude was set at 3.9, Gu said.

Could be largest quake in Canada

If it is revealed that fracking induced Tuesday's 4.8 quake, Gu said, it would be the largest such quake in Canada's history.

A 4.6 magnitude fracking-related earthquake in B.C. in August was confirmed by scientists as the largest so far in Canada, perhaps even the world.

Alberta Premier Rachel Notley said her officials are looking into Tuesday's quake.

"The AER has been engaged in a review of fracking, in particular as it relates to this issue, and I'll be asking them to speed that review … to come up with some recommendations that we can consider sooner than later."

Area resident Jesse Christensen was in Fox Creek at the time of the quake.

"We were all just kind of standing around … and everybody just looked at each other and said, 'Did you feel that?'

"It didn't feel uneasy or anything," he said. "It was just like some shaking through your feet a little bit, but not too much."

Fox Creek, 263 kilometres northwest of Edmonton, is a town of about 2,000 people largely sustained by oil and gas development.