The daughter of a friend of mine lives in Chicago and she was wondering if we had experienced a 'frost quake.'

Since I have no idea what that is...couldn't tell ya.

So I looked it up.

WLFI/West Lafayette, Indiana meteorologist Balint Szalavari explains that a cryoseism, or frost quake, happens "when extremely cold temperatures lead to rapid freezing in the ground after it has been saturated."

This, in turn, creates a booming noise when the ice expands in the ground.

It seems they're more commonly heard at night, when there's less noise with which they can compete.

Here's a demonstration:

And here's an actual frost quake:

I think this is really cool, but it IS helpful to know they exist so, if you hear one, you don't jump out of your skin.

Happy frost quake hunting!