cryoseism

A cryoseism, ice quake or frost quake, is a seismic event caused by a sudden cracking action in frozen soil or rock saturated with water or ice, or by stresses generated at frozen lakes. As water drains into the ground, it may eventually freeze and expand under colder temperatures, putting stress on its surroundings. This stress builds up until relieved explosively in the form of a cryoseism. The requirements for a cryoseism to occur are numerous; therefore, accurate predictions are not entirely possible and may constitute a factor in structural design and engineering when constructing in an area historically known for such events. Speculation has been made between global warming and the frequency of cryoseisms.

== Effects == Cryoseisms are often mistaken for minor intraplate earthquakes. Initial indications may appear similar to those of an earthquake with tremors, vibrations, ground cracking and related noises, such as thundering or booming sounds. Cryoseisms can, however, be distinguished from earthquakes through meteorological and geological conditions. Cryoseisms can have an intensity of up to VI on the Modified Mercalli Scale. Furthermore, cryoseisms often exhibit high intensity in a very localized area, in the immediate proximity of the epicenter, as compared to the widespread effects of an earthquake. Due to lower-frequency vibrations of cryoseisms, some seismic monitoring stations may not record their occurrence. Cryoseisms release less energy than most tectonic events. Since cryoseisms occur at the ground surface they can cause effects right at the site, enough to jar people awake.