Rare frost quakes shook Indiana over the weekend

An odd phenomenon shook parts of the Hoosier State over the weekend thanks to the recent up-and-down weather pattern. Most people have never heard of them, but they have been around forever. They are called cryoseisms, or frost quakes. Yes, that means they are technically in the same family as earthquakes.

"Almost sounds like a gunshot. When you hear them it sounds like something hitting against your house. It's a really strong phenomenon," says meteorologist Mike Ryan of the National Weather Service in Indianapolis. 

These quakes aren't as dangerous or severe as they may sound, however. They are known for causing a loud noise that resembles a pop or boom thanks to sudden cracking that occurs in frozen soil that is saturated with water or ice.

And conditions across Indiana were ideal for them over the weekend. A warm air mass moved in from the Gulf of Mexico on Wednesday and Thursday. That caused the snow pack across the state to melt. In addition, a healthy rain fell statewide Thursday and Thursday night. When you add melted snow and fresh rain to the ground, the soil becomes saturated with water. As temperatures fell quick and far Thursday night into Friday, that water froze in the soil. And, as water freezes, it expands and tries to take up more space. That results in stress on surrounding soil, which, in turn, needs to be relieved in some way. That is where the gunshot-like sound comes into play. To relieve the stress, the ground will simply crack or possibly even break apart in spots to allow the frozen water to expand. This is what caused the loud noises that many across Central Indiana heard over the weekend.

"Random pops if you will. We got reports of that all over central Indiana Saturday night and Sunday morning."

Despite them occurring over the weekend here in Indiana, they are a rather unusual phenomenon. 

"It seems like these situations happen every couple of winters when the conditions set up right," Ryan says. He went on to say that these events happen once or twice every three to five years or so. This makes them uncommon to down-right rare. 

Unbelievably, these frost quakes can be strong enough to register on seismometers, or instruments that register and measure earthquakes. They can also cause damage if they are strong enough, but this is extremely rare and usually is not the case.

So, the million dollar question: "Do I need to stress over frost quakes?" 

No. Since they require a handful of ingredients to come together just right, they are impossible to predict, and far too atypical to lose sleep over. Even if one were to occur near your home, you would likely only hear a loud noise and nothing more.