What Is #12: A Frostquake

The 'What Is' Series

A couple of months ago I started a new series on this blog titled "What Is". Thus far the focus is on the field of astronomy where we hear all sorts of cool science taking place in space. The goal of this series is to explain the details of different objects we hear about relatively frequently.

Very Cold Weather

Today's topic in this series is not directly related to astronomy, but is connected to Earth science and is very applicable to this year's winter in the United States. Thus I'm including it in this series. Much of the United States experienced very cold temperatures and wind chills at the end of January 2019. The jet stream dipped very far south, bringing cold arctic air to lower latitudes. Areas of the United States experienced wind chills as cold as -60 degrees Fahrenheit. Where I live we had a low wind chill of -39 degrees. BRRRRRR!!!!

Very cold temperatures can also be bring some weird noises that include creaking and moaning of your house. That is normal and happens to every house and happens frequently. What doesn't happen all that often are loud booms called frostquakes.

Frostquakes

The official name of frostquakes is cryoseism, but frostquake has a sexier sound to it. Frostquakes occur when water in the ground freezes, causing the pressure to build up in the ground. When this pressure is released, a loud boom can occur. Frostquakes normally don't happen as the pressure is usually slowly released. But if the ground has a lot of water in it and temperatures drop very quickly, the water freezes quickly and the pressure builds up quickly. Without a slow release of this pressure, it releases at once and produces a loud boom known as a frostquake.

This winter is one of the very few I've experienced where I've heard frostquakes. I've heard a couple this year. The first occurred when I was sitting in the living room. The temperature had dropped quickly and the house was creaking and moaning. All of a sudden there was a boom outside the exterior wall. At first I thought something had struck the house, but the boom sounded a bit too deep for that. It was later when I read about frostquakes that I realized what I heard.

So there you go. Frostquakes.