A 4.6-magnitude earthquake rattled central Alberta Monday morning.

The quake occurred about four kilometres southwest of Red Deer at 5:55 a.m., Earthquakes Canada confirmed in a report on its website. Earthquakes Canada initially reported the epicentre was about 35 kilometres north of Red Deer.

The one-kilometre-deep quake was "lightly felt" by residents in Red Deer and Sylvan Lake, the report said.

People reported on social media that tremor temporarily knocked out the power in some areas of Sylvan Lake.

Colleen Jesse was asleep on the couch in her fourth-floor apartment in downtown Red Deer when the quake startled her awake.

The couch was shaking and everything is moving. -Colleen Jesse

"All of a sudden, the couch was shaking and everything is moving in my apartment," she said. "I sit up ... and I'm going, 'Is my apartment falling down?' And I look out the window and there is nothing.

"It was pretty scary."

Red Deer, Alta. resident Colleen Jesse describes what Monday morning's earthquake felt like in her apartment. 1:06

Jesse said her four-month-old Maltese puppy started barking as the windows began to rattle and shake.

Jesse said it was an unnerving morning. She feels grateful the quake wasn't more powerful.

"[The dog] was looking around wondering what was going and he's kind of growling because he was wondering too, why is everything shaking?

"It was pretty frightening, especially on the fourth floor."

Hydraulic fracturing in area

The Alberta Energy Regulator said the earthquake was detected Monday morning about 12 kilometres south of Sylvan Lake. The seismic activity was reported at 6:20 a.m. by Calgary-based oil and gas operator Vesta Energy, the AER said.

"Vesta Energy was conducting hydraulic fracturing activities in the area, but has since stopped," said Natalie Brodych, a spokesperson with the AER.

Vesta Energy crews were doing work in the area when the quake hit early Monday. (Dave Bajer/CBC) "We are currently reviewing the events to determine if the incident is due to hydraulic fracturing activities or natural causes."

There has been no reported impact on public safety, infrastructure or the environment, the AER said.

A statement from Vesta Energy said the company's monitoring equipment detected a 4.32 magnitude seismic event about 20 kilometers southwest of Red Deer.

The company said it has shut down operations in the area and is working with the AER to investigate.

"Safety of the public and our employees is paramount at Vesta Energy," the company said in an emailed statement.

"The company has real-time seismic-monitoring equipment on site which will be used in its investigation of the situation."

The Geological Survey of Canada has received numerous reports from residents who felt the rumble, said Taimi Mulder, an earthquakes seismologist with the agency.

"People that felt the earthquake said dishes have rattled," Mulder said told CBC News.

"Some people have described it as a truck slamming into the house, so they felt a very short, sharp shock."

It's unlikely the earthquake was powerful enough to cause any damage, Mulder said.

Earthquakes unusual in area

Earthquakes are unusual in the area but not unheard of, said David Eaton, Industrial Research Chair in Microseismic System Dynamics and a professor with the Department of Geoscience at the University of Calgary.

There is a link between fracking and earthquakes but the cause of Monday's seismic event remains unclear, he said.

Some areas of the province are more prone to earthquakes, whether they are triggered by natural or man-made forces, Eaton said. Long-term monitoring across the province is important to manage that risk.

"There is no scientific evidence if there is a trend upwards or downwards in terms of the intensity, but it's something that we would like to better understand for the safety and security of Albertans," Eaton said.

"Further study on these kind of earthquakes is very much something that were very much interested in doing ... we're really interested in trying to understand the root causes."