Perhaps you've heard a loud, unexplained boom this winter.
It's possible it could be a phenomenon brought on by extreme cold: a frost quake.
What is a frost quake?
A frost quake happens when groundwater freezes and expands during extreme cold temperatures, according to meteorologist Ryan Knutsvig of the National Weather Service office in Lincoln.
The loud bang people hear is the sound of that expansion.
People in Peoria, as well as in Iowa and Minnesota, have wondered about the overnight booms they have heard this month when temperatures have been near or below zero.
The weather service doesn't track frost quakes — unlike earthquakes, which are pinpointed by time and location. Frost quakes can occur with rapid temperature changes.
"The groundwater deep below the surface freezing can lead to those noises because of the ground shifting to compensate," Knutsvig said.
Areas of Peoria that have more groundwater — including being saturated after a recent snowmelt — could be more susceptible to frost quakes. They typically require a combination of extreme cold and no snow.
This article originally appeared on Journal Star: What's a frost quake? Peoria weather may explain mysterious booms