cryoseismic boom

A cryoseismic boom, also known as a cryoseism or icequake, is a geological phenomenon caused by the rapid freezing of water in saturated soil or rock. This process creates seismic vibrations, loud booms, and ground shaking, which can be mistaken for true earthquakes.1

Cryoseisms are not related to tectonic activity. Instead, they occur when groundwater freezes and expands, building up pressure within the soil and rock. When this pressure becomes too great, the ground fractures, releasing energy that causes the audible booms and seismic waves. These events are common in regions with sudden temperature drops and little snow cover, often happening in the early morning hours. They can also occur when glaciers move suddenly. An icequake specifically refers to the concussion produced by the breaking up of large ice masses.12