Is it possible to hear a cryoseism in Chicago?
Is it possible to hear a cryoseism in the city itself, and is it possible to experience one with the weather we are having now?
— Frederica Malone,
During intensely cold temperatures, water in the ground freezes at the surface, capping water in the soil beneath it so pressure can build up as that water also begins to freeze. Ice occupies a slighter greater volume than the water from which it comes, and usually, as the water freezes, this results in only a gradual widening of cracks in the soil. In a cryoseism, the pressure is released all at once, resulting in a “mini-earthquake.” Such quakes are almost always harmless but can produce a popping noise. A few cryoseisms have been reported across northern Illinois in recent days, and they can occur in the city and in suburban areas.