CHICAGO — Did you hear loud booms or banging sounds overnight in Chicagoland? Those sounds might have been cryoseisms, or frost quakes.
So, here's how a frost quake happens:
First, the ground has to be saturated with water, like it is in the Chicago-area right now with all the snow.
When there's a sudden drop in temperature, the water freezes and expands.
The expansion and pressure build up causes stress on the frozen soil and rocks around it, and creates a boom noise.
When WGN first posted about frost quakes on social media, tons of comments poured in from our viewers about hearing them.
"I thought I was crazy! I was up all night because I kept hearing it," said viewer Chastity Clark Baker on Facebook. "I was scared and thought it was the furnace. I kept walking through the house. I had everyone’s jackets on the table in case we had to run out of here."
Did you think you heard a frost quake? Tell us on WGN's Facebook page.