An ice quake, also known as a cryoseism 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. When water in the ground freezes very quickly, it expands and breaks up the soil and rocks around it, causing the ground to shake. Here are some key facts about ice quakes:

• Causes: Ice quakes are caused by a rapid temperature drop from approximately freezing to near or below zero degrees Fahrenheit, which ordinarily occurs on a timescale of 16 to 48 hours. A region must be susceptible to cold air masses, and the ground must undergo saturation from thaw or liquid precipitation prior to an intruding cold air mass. Most frost quakes are associated with minor snow cover on the ground without a significant amount of snow to insulate the ground (i.e., less than 6 inches) .

• Similarities to earthquakes: Both ice quakes and earthquakes cause the ground to shake and can be measured by seismographs. However, the biggest difference between the two is how they’re caused.

• Location: Ice quakes are common across Antarctica, and experts there say Earth’s coldest continent has had hundreds of thousands of them in recent years. They also occur in Greenland, most often near glaciers, and in Canada, as well as in the midwestern and northeastern United States.

• Effects: Most ice quakes are much weaker than earthquakes, and people often don’t feel them at all. However, they can usually be heard, making a loud pop or boom. The Encyclopedia Brittanica reports that frost quakes can sometimes be mistaken for true earthquakes because of how intense the seismic vibrations can get, and they’re more common in polar and mountainous regions where glaciers move.

Overall, ice quakes are a fascinating natural phenomenon that occur in cold regions of the world. While they can be startling to experience, they are generally harmless and not a cause for concern.