A map shows where reports have come in from Albertans who felt Wednesday night's earthquake. (earthquakescanada.nrcan.gc.ca)

By Josh Hall (Twitter: @Vancan19)

LARGEST ON RECORD SINCE 1985

Earthquake near Rocky Mountain House upgraded to Magnitude 5.0

Oct 22, 2021 | 10:33 AM

An earthquake which occurred at 9:23 p.m. on Oct. 20 has been upgraded from Magnitude 4.1 to 5.0.

Andrew Schaeffer, research scientist with Geological Survey of Canada, tells rdnewsNOW the quake has been confirmed by the Alberta Energy Regulator to have been naturally occurring, as opposed to induced.

He also notes the depth of nine kilometres (previously thought to be 10 km) is a good indicator of that, with induced earthquakes typically much more shallow.

“This earthquake was the largest in the Rocky Mountain House area since our catalogue came about in 1985,” Schaeffer shares.

“This region isn’t an area that’s under active tectonic deformation, such as in southwest B.C., but the Rocky Mountains, while old, are relatively young, and the process of building them has created all sorts of faults. As a result, these little earthquakes go off not infrequently.”

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In the last 20 years, there have been about 10 earthquakes in the region above 4.0, but below 5.0. Schaeffer says those measuring in the magnitude 2-3 range number in the hundreds.

Originally pegged at 37 km NNW of Rocky Mountain House, Earthquakes Canada now lists the rumbler at 31 km WNW of the municipality.

There have still been no reports of damage, though reports of feeling the earthquake have been reported from places as far away as Hinton, Vegreville and Claresholm.

If you felt it, Earthquakes Canada invites you to fill out their questionnaire.