Some Peace Country residents had a shaky start to their Thursday morning; however, this was not the case for everyone.
On February 20th, a 4.7 magnitude earthquake out of the Grande Cache region shook parts of northwestern Alberta and was felt as far away as Prince George.
So what happened in Grande Prairie? According to Natural Resources Canada Earthquake Seismologist Taimi Mulder, not much. She says very few reports came in from Grande Prairie specifically, with the bulk of them coming from the surrounding area.
“ It’s not a simple thing, how people feel an earthquake,” she says.
Mulder says she found it “quite interesting” that the quake went relatively unnoticed in Grande Prairie, but was felt further away in places like Prince George, which is much further from the epicentre than Grande Prairie.
“The closer you are to the epicenter, the more strongly you’re going to feel the earthquake,” she says. “ As you go further away, those seismic waves die out or get attenuated, and you feel the shaking is less strong.”
“You’re just sort of on the edge of the stronger shaking.”
The seismologist adds that another reason could be what scientists call “earthquake directivity effects,” which can influence where the quake is felt, which in this case resulted in Grande Prairie “dodging” the quake that morning.
“ That means that some waves go out more strongly in one direction than another, and this varies from earthquake to earthquake, so there’s really no being able to tell ahead of time what that’s going to be, and in this case, it looks like the stronger shaking went sort of northwest and southeast.”
Ultimately, Mulder says the reality could also be the simple fact that the quake occurred at a time when most of Grande Prairie was waking up, having breakfast, or on their morning commute, making it less likely for them to feel the quake altogether.
“If you’re seated or lying down, you’re going to be much more aware of the earthquake than if you’re up and walking around or perhaps in your car or on the bus and you might not notice it at all,” she says.
Earthquakes Canada has yet to receive any reports of damage as a result of the event.
