FROST QUAKES ARE OFTEN NOT MEASURABLE: But it doesn't make them less scary. (Photo: °Florian/Flickr)
The plunge in temperatures last week not only brought on the need for long johns and extra socks, but also an eye-opening jolt of terror in the middle of the night for our neighbors in Indiana and Ohio.
Awakened by loud noises and shaking knick-knacks, some residents thought they were witnessing an earthquake. Not so. The temperatures that dropped well below zero caused a winter phenomenon better known in New England as a frost quake.
A frost quake, or cyroseism, usually happens in the wee hours when the air dips well below zero degrees (Fahrenheit). The ground must be drenched with water, whether by snowmelt, rain, sleet or ice, and have little snow cover to insulate the ground. The frost quake results from this moisture in the soil and bedrock quickly freezing, creating a lot of stress on the environment. Rocks crack and explode. The ground shakes with tremors sometimes lasting for hours. Fissures can even develop.
But just because you're having a frost quake at home doesn't mean your neighbors will experience one, or even notice it. Unlike an earthquake, these winter phenomena are localized and lose energy once the stressors are released (though they can cause property damage and/or just plain scare the heck out of you!).
According to the Maine Geological Survey, not much is generally known about cyroseisms, since their incidence is random and due more to weather conditions than components of the soil and geological area. Besides New England, they are known to occur in Alaska, Canada, Iceland and Greenland.
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