Extreme cold in parts of North America is causing a strange weather phenomenon — frost quakes.
A quake was most recently experienced in Chicago on Wednesday, as the city grappled with some of its coldest weather to date when temperatures plummeted to roughly -30 C.
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Those living in Perth Road, Ont., a community north of Kingston, also experienced a frost quake earlier this month, and similar instances have also been reported in parts of Alberta.
What exactly are frost quakes?
Frost quakes, also known as ice quakes or cryoseisms, are loud noises — so loud they often cause the ground to shake.
Global News’ chief meteorologist Anthony Farnell explained that the quakes happen during extremely cold weather.
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“When water freezes it expands and this expansion creates stress on the ground or rocks,” he explained. “Eventually the stress is released explosively.”
Farnell said the noise can be heard from kilometres away and even feel like an earthquake.
While they’re not very common, frost quakes can occur across Canada. They’re most common around the Great Lakes and Quebec.
“In the winters of 2014 and 2015 when the Polar Vortex brought record cold to central Canada, frost quakes were reported almost daily,” Farnell noted.
Can they be dangerous?
While they have a similar name to earthquakes, they are far from the same thing.
“Earthquakes are a very different phenomenon and have to do with plate tectonics and movements well below the surface of the earth,” Farnell explained.
Frost quakes, however, can cause some minor damage.
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How do you know it’s a frost quake?
It can be difficult to know whether you’ve experienced a frost quake because the sound is brief and there are often no visible signs.
For example, those who heard the Perth Road quake thought it may be a plane or car crash.
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One resident, Jason Potter, thought his neighbour, who owns a seaplane, had crashed.
A piece of equipment at Queen’s University, a superconducting gravimeter, is one of only 30 in the world that can detect frost quakes.
Alex Braun, a geological engineering professor at the university, explained that the equipment costs about half a million dollars.
WATCH: Queen’s University expert explains what frost quakes are
“It is the most sensitive gravimeter on earth,” he said.
“So people around that area, about a five- to 10-kilometre radius, they would have heard what was happening,” Braun said of the Perth Road quake.
Farther away, Queen’s University’s instruments also felt seismic waves, which Braun explained “travelled through the ground.”
— With files from Global News reporter Neil McArtney