The earthquake happened at 4 a.m. around 30 kilometres northwest of Rocky Mountain House, according to Natural Resources Canada. The quake was about 10 kilometres deep.
No damage has been reported. Only minor damage — if any — would be expected with an earthquake of this magnitude, says David Eaton, a professor with the Department of Geoscience at the University of Calgary.
However, those living in the area would feel it, he said.
"This is an area that is prone to earthquakes," Eaton said.
"It's right in that zone where you do expect people who are in proximity to the epicentre to feel it quite strongly."
There are several clusters of seismicity in the area that are well-known and studied in the area around Rocky Mountain House, Eaton added. One of them was active in the late 1980s and early 1990s and was linked to production from the Strachan oil pool, he said.
It's right in that zone where you do expect people who are in proximity to the epicentre to feel it quite strongly.-David Eaton
He could not say what caused Sunday's earthquake.
"It's an area which has a long kind of history known to be seismically active, and it predates any kind of hydraulic fracturing types of operations that have really ramped up in the last five to 10 years," Eaton said.
The Alberta Energy Regulator is aware of the earthquake but spokeswoman Cara Tobin couldn't confirm whether it was related to industrial activity.
"While we cannot say absolutely either way at this time, it is unlikely to be related," she said. "There is no drilling or completion activities in the area at the moment."
In August 2014, a 4.3 magnitude earthquake struck in a similar location, she added.
Second quake in six days
This is the second earthquake in Alberta within one week.
The morning of March 4, a 4.6-magnitude earthquake struck about four kilometres southwest of Red Deer.
The one-kilometre-deep quake was "lightly felt" by residents in Red Deer and Sylvan Lake, according to Natural Resources Canada.
People reported on social media that tremor temporarily knocked out power in some areas of Sylvan Lake.
One resident in downtown Red Deer said she was asleep on her couch when the earthquake startled her awake last week.
"All of a sudden, the couch was shaking and everything is moving in my apartment," Colleen Jesse 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."