Frost quakes: What are they?

Have you experienced a cold winter, a really, really cold winter? If you have, it is possible that you have experienced a rare geological event known as a frost quake. 

Unlike earthquakes, frost quakes are non-tectonic seismic events, meaning that they are not brought on by the Earth’s tectonic plates shifting.

In the winter, besides just getting snow, there is also frost that occurs. When a solid surface cools to below the dew point of the surrounding air and small particles that look kind of like spikes grow out from the surface, you get frost. (Generally, frost quakes only happen when the temperature falls from above freezing to below freezing very rapidly.)

Solid surfaces are not the only things that reach freezing temperatures. Water reaches freezing temperatures, as well. And it is not just the water in streams, rivers and lakes that freezes. Water inside of the ground, which seeped into the soil after a rainfall or snowfall and became trapped there, freezes as well.

The water closest to the surface of the ground freezes first. The colder the weather is and the longer it remains that cold, the deeper down the water in the ground will be frozen. Well, when water freezes, it expands. So, sometimes, the frozen water in the ground expands to the point that it runs out of space and needs more. The soil and the rock surrounding the frozen water crack under the pressure of the expanding frozen water. The act of the frozen water making more space for itself in the ground is called cryoseism.  This causes a loud, explosive sound to pierce through the air.

Not only will it be loud, but as with an actual earthquake, the ground will shake. You have to be very nearby in order to feel the frost quake. If you are a few miles away, chances are that you will not even notice that it is happening.

The frost quakes have been measured on the same machines that measure earthquakes. This machine is called a seismograph. The highest recorded frost quake was a 1.5.

Frost quakes are relatively rare in the United States because of how cold t needs to be for the event to occur, but they have been documented as occurring in northern New England and Alaska.

Frost quakes can cause serious damage, such as fissures in roads and the cracking of building foundations.

They are often very localized, but it is possible for multiple quakes to occur in a particular area. The ‘season’ for frost quakes is very short. There are never reports of frost quakes happening before late December or late January and never after March. The reason for frost quakes not occurring earlier in the winter season is because there has to be enough frost inside the ground in order for cryoseism to take place.

So, don’t think that you live in an area that will never experience a quake because you might just be proven wrong some cold, cold, cold winter day.