Icequake is a geological term that describes a sudden cracking or rumbling sound caused by the breaking and shifting of ice in extremely cold regions. Synonyms for icequake include frost quake, cryoseism, ice thump, glacial earthquake, and frozen explosion. Frost quake is perhaps the most commonly used synonym and is often used interchangeably with icequake. Cryoseism emphasizes the seismic tremors caused by the ice movement and is a more technical term. Ice thump and frozen explosion both denote the sudden sound produced by the movement or breakage of ice, whereas glacial earthquake highlights the intensity and potential danger of the event.