'Frost quake' may have caused loud boom in Calgary

(FILE PHOTO)

(FILE PHOTO)

Bill Kaufmann, Calgary Sun

, Last Updated: 7:21 AM ET

CALGARY -- Winter’s chill might have literally lowered the boom on northwest Calgarians, say meteorologists.

It’s plausible that a loud cracking noise and shaking sensation detected by residents late Tuesday afternoon was a so-called frost quake, said Environment Canada meteorologist Colin Tam.

“The theory of a frost quake does seem pretty viable,” said Tam.

Melted snow water from the thaw that preceded the recent cold snap seeped into the earth and rocks beneath, said Tam.

It’s possible that it then froze in the following severe weather that dipped to windchills of around -40C, causing a rapid subterranean ice expansion that led to a booming sound and seismic activity.

The ground-stress phenomenon known as cryoseisms is thought to have occurred in southern Ontario, said Tam, in early January during one of the polar vortex events.

“It seems quite reasonable to think these two are fairly similar,” he said.

A similar action occurs on a smaller, more gradual scale in roadway frost-heaving that leaves cracks and potholes, said Tam.


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