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Rare 'frost quake' phenomenon bewilders Greater Toronto Area residents

Categories: Canada, Community

A major ice storm devastated parts of the Toronto. (Ivy Cuervo/CBC)

A baffling boom on Christmas Eve that rattled Greater Toronto Area residents reeling in the wake of an ice storm was likely a rare phenomenon known as a frost quake.

Residents in the GTA and surrounding areas took to Twitter with reports of mysterious booms late Christmas Eve and early Christmas Day that even jarred many awake from slumber.

With the area encased in ice following a nasty mix of rain and snow Sunday, many believed ice or a tree limb had fallen on their rooftop.

As first reported by Global Toronto, the U.S. Geological Survey did not register a seismic event in Ontario on Christmas Eve or Christmas Day and there were no reports to the American Meteor Society, ruling out comets or meteors, and leaving a cryoseism, or frost quake, as a likely explanation.

A rare  phenomenon, cryoseisms usually "occur when temperatures go from above to below freezing," says CBC News meteorologist Michelle Leslie. 

"Water in the surrounding soil and rocks freezes. As water freezes, it expands, putting pressure on the dirt and rocks," she says.

"When the pressure build-up is too much, the dirt or rocks will crack, and you hear a loud boom."

They tend to occur between midnight and dawn, the coldest time of night and are very localized, so residents a few blocks away may not have heard the Christmas Eve or Christmas day booms. 

In Toronto, an extreme cold weather alert was in effect Tuesday, and temperatures were well below freezing in the GTA and surrounding areas. 

Some 250,000 residents in Toronto were without power following the major ice storm and tens of thousands are in their sixth day without electricity.

Editor's Note: This story has been rewritten to acknowledge a previously published story by Global Toronto titled "Mysterious Christmas Eve 'boom' heard and felt around GTA." Parts of our story resembled too closely the original Global article.

Tags: Frost Quake, Greater Toronto Area, Ice storm, Ontario, Storm, Toronto

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