Early morning 'boom' may have been 'frost quake'


Indianapolis - Many WTHR viewers reported hearing a loud boom early Thursday morning.

We've heard from people in Geist, Avon, Mooresville, Anderson, Noblesville, Decatur Township and in Randolph County. Residents described hearing a loud booming sound that woke them up, and some said their dishes rattled. One person says they thought their roof was collapsing.

An expert says the loud booms are probably something called "frost quakes" from all of the ice built up during the ice storm. The frost quake phenomenon is caused by a sudden cracking in soil or rock caused by the freezing and expanding of water.

"It's like a very soft explosion actually. It's like someone ran into something outside," said Dr. Gabriel Filippelli, IUPUI geology professor. "Unlike an earthquake where you feel it across hundreds or thousands of miles, these frost quakes are really localized because it doesn't freeze very deep."

The technical term is cryoseism - also known as a frost quake.