What was that really loud sound I heard last night? A cryoseismic boom!

Yep, that's right.  That sound you heard was a 'COOL' weather phenomenon also called a cold boom.  Technically, it is known as a cryoseismic boom. A phenomenon reserved for only the coldest of temperatures and rare for the lower latitudes of the continental United States.  The boom sound is created by a cryoseism, which is a mini explosion within the ground caused by the rapid expansion of frozen water.

Cryoseisms usually occur when temperatures rapidly decrease from above freezing to subzero, and are more than likely to occur between midnight and dawn (during the coldest parts of night). In general, cryoseisms may occur 3 to 4 hours after significant changes in temperature. Perennial or seasonal frost conditions involved with cryoseisms limit these events to temperate climates that experience seasonal variation with subzero winters. Additionally, the ground must be saturated with water, which can be caused by snowmelt, rain, sleet or flooding. Geologically, areas of permeable materials like sand or gravel, which are susceptible to frost action are likelier candidates for cryoseisms. Following large cryoseisms, little to no seismic activity will be detected for several hours, indicating that accumulated stress has been relieved. (wikipedia)

The library has many fascinating books and dvds on weather and weather phenomena.  Come on down and borrow them.  Or if it's too cold, you can stream documentaries from kanopy on extreme weather from the warmth and comfort of your home while sipping a delicious hot chocolate. If you seem a hear a loud boom between midnight and dawn, you need not fear an earthquake or an explosion.  It just the the ground crying out that it is too darn cold.  Stay warm everyone!