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Loud booms around the St. Louis area have residents worried there's been an outbreak of earthquakes, but News 4's Russell Kinsaul talked to experts and found out the "booms" are called "Frost quakes."

Frost quakes occur when water soaks into the ground, freezes, and quickly expands. The quick expansion can suddenly move large amounts of soil and cause small earthquakes.

"I was sitting right here in this room and I heard and really loud boom," Fairview Heights resident Susan O'Mara said.

O'Mara said she heard the sound on Monday at her home. The noise was so loud, she said she looked out side because she thought a car ran into a neighbor's house but didn't see anything.

"I didn't know what it was. A little shake to the house. I thought it was an earthquake."

According to experts, frost quakes have been known to put cracks in streets and the foundations of homes and buildings, but that is very rare.