CHICAGO — Loud booms or banging sounds reported overnight in Chicago might have been cryoseisms, or frost quakes, caused by the brutal cold gripping the Midwest this week, according to WGN.
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."
Another viewer commented: "I was up all night thinking it was the pipes, roof or the furnace!"