Earthquake near Rocky Mountain House upgraded to 5.0 magnitude

A chorus of “Did you feel that?” erupted in homes across central Alberta Wednesday night when a 5.0-magnitude earthquake shook the ground.

The quake hit just before 9:30 p.m., about 37 kilometres northwest of Rocky Mountain House in Clearwater County. It was originally measured as a 4.1-magnitude quake, but Earthquakes Canada upgraded the magnitude to 5.0 on Thursday.

That makes it the largest earthquake in the Rocky Mountain House area. Previously, the region had experienced three 4.6-magnitude earthquakes: one in 2015 and two in 2019, according to Earthquakes Canada.

Kathy Dougall and her husband were inside their RV at the Wilderness Village Resort campground, located about 20 kilometres northwest of Rocky Mountain House, when their world shook.

“We were sitting in our recliners, watching a movie, when we felt the whole RV shake just for a second or two,” Dougall said Thursday morning.

“I looked at my husband to see what he was doing with his chair to be so disruptive. And he thought it was me.”

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Once the pair determined it was neither of them, their thoughts turned to what might be outside. A bear? Mischievous friends?

“It really surprised us. Got our flashlights out, looked out all the windows and couldn’t find anything so kind of freaked out, being kind of isolated up here.”

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Eventually, Dougall searched “Rocky Mountain House” and “earthquakes.”

“And sure enough, there had been activity in Rocky Mountain House, and there was comments that it reached as far as Edmonton.”

Natural Resources Canada earthquake seismologist Andrew Schaeffer said Alberta experiences a fair number of quakes, which become more prevalent the further west you go.

“Across much of Alberta there are indeed very few earthquakes, but as you get closer to the B.C. border, the Rocky Mountains, they become more common,” Schaeffer said.

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The Rocky Mountain House area of central Alberta has experienced more than 500 earthquakes in the last 30 years or so, but few would have been strong enough to be felt, he added.

“More than 400 of these are less than magnitude two or less,” he said.

“There have been about four or so magnitude four events in the last 30 years, so there’s been a few.”

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The area lays at the edge of the foothills that build up to the Rocky Mountains. Despite the mountain range being hundreds of millions of years old, Schaeffer said it still has occasional seismic activity.

And while there are parts of Alberta where there is induced seismicity caused by humans from activities like fracking, the quake on Wednesday was natural and occurred from 10 kilometres deep in the earth.

“A magnitude four like this — that’s enough to get some attention,” he said Thursday morning. “And since the report went out last night, we’ve now got another couple hundred reports, so certainly fairly widespread across this portion of Alberta. ”

Schaeffer said people in as far north as Edmonton reported feeling the quake, which wasn’t the only one Alberta has experienced this month.

4:50 Earthquake detected near Rocky Mountain House

Three earthquakes were reported in October prior to Wednesday night. A 2.9-magnitude earthquake occurred on Oct. 2 about four kilometres north of Edson.

On Oct. 5, a 3.9-magnitude earthquake hit about 77 kilometres south of Grande Cache, where three days later a 3.3-magnitude earthquake transpired about 73 kilometres northeast of the community.

Since 2010, there’s been about 230 other earthquakes of varying magnitudes throughout Alberta.

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Earthquakes Canada encourages people to report quakes via the Did you feel it? form on its website.

Schaeffer said the data submitted helps scientists map the small scale ground amplification, which ultimately feeds into national seismic hazard models and influences national building codes.

There were no damage reports from Wednesday’s tremor, Earthquakes Canada said.

— with files from Phil Darlington and Kaylen Small, Global News and Kirby Bourne, 630 CHED