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frost quake or frostquake also ice quake, icequake

noun [countable]

a deep loud sound made when frozen soil or rock suddenly cracks

'Loud booms startled sleeping Canadians last week when bitterly cold temperatures triggered an unusual weather event called frost quakes.'

Live Science 8th January 2014

'The series of explosion-like sounds rattled residents from Waupun, Campbellsport and elsewhere Tuesday and sent Fond du Lac County sheriff's deputies out looking for a cause. Geologists say the booms were likely a phenomenon commonly known as an ice quake.'

StarTribune 9th January 2014

In the early days of 2014, people in parts of Canada were having their sleep abruptly disturbed by random explosive sounds the like of which they had never experienced before. These large booms caused people across Ontario to think that their homes were being broken into or that gunshots were being fired, when in fact there was a very simple, and far less sinister, explanation. Extremely low temperatures had resulted in episodes of a rare natural phenomenon known as a frost quake.

though its resemblance to an earthquake may conjure up images of danger and destruction, a frost quake is by comparison pretty harmless, just rather noisy

A frost quake, also sometimes described as an ice quake, is a loud, deep, booming sound produced by a particular sequence of meteorological events. Heavy rainfall causes the ground to become saturated with water, which sinks deeply into soil and bedrock. If the temperature then drops very sharply, this water freezes and expands, causing the earth to crack. The result is an explosive popping sound which feels like a mild earthquake. Though its resemblance to an earthquake may conjure up images of danger and destruction, a frost quake is by comparison pretty harmless, just rather noisy.

Frost quakes are usually confined to polar regions. However, they typically strike after a rapid temperature drop, so in early January when temperatures in Toronto plummeted overnight to as low as -20 degrees, people across the city were abruptly startled by a unique occurrence of the same phenomenon.

The big chill that hit Canada and parts of North America in early 2014 has thrown a couple of other expressions into the spotlight. Reports on the weird and wonderful experience of frost quakes often characterize the related weather situation as a polar vortex. This expression refers to cyclones (rotating winds) which originate from the Arctic and cause extremely harsh, bitterly cold conditions. And such conditions are not only problematic and uncomfortable, they can also now lead to US citizens being prosecuted if they unwittingly launch an ice missile. This expression refers to the large chunks of compacted snow and ice which can fly off a vehicle as it moves along at speed. Ice missiles have the potential to cause serious injury or damage to surrounding people or things, and so a new law has been passed in the US which can fine people $75 for not clearing snow/ice from their cars, and as much as $1000 if it flies from their vehicle and results in injury or damage.

Background – frost quake or ice quake

The expressions frost quake and ice quake are of course formed by analogy with the word earthquake (= noun earth + verb quake meaning 'shake violently'). Though earthquake dates as far back as the 13th century and only appears as a single word in contemporary English, frost quake and ice quake still appear to be at that intermediate state of lexicalization characterized by the co-occurrence of closed (one word) and open (two word) forms.

In more technical contexts, frost/ice quakes are also referred to as cryoseisms. This word is formed from a combination of the affix cryo- meaning 'very cold or freezing' and the form seism, as found in seismic, seismology etc, in reference to earthquakes. Seismo- is a word-forming element originating from Greek, meaning 'shaking'.

by Kerry Maxwell, author of Brave New Words

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This article was first published on 28th January 2014.

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