Frost quakes are startling residents throughout the Midwest. As the rare phenomena often produces unexplained lights and loud noises, many residents thought they were experiencing earthquakes. Although they may sound frightening, frost quakes pose no danger to people or structures.
Cryoseism, also known as frost quakes, are most often experienced in the winter during a deep freeze. During Cryoseism, moisture that is trapped underground become frozen at a high rate of speed. As the frozen sections expand quickly, they often crack, break, or explode.
Depending on the size of the section and the extent of the break, the resulting cryoseismic boom can sound like a breaking branch or a small rumbling earthquake. Although the exact cause of the accompanying lights is unknown, researchers believe they are related to electrical charges. As the charges are released from compressed rock, they may travel to or above the ground’s surface.
Robert Herrmann, a scientist with the Saint Louis University Earthquake Center, said frost quakes can be quite loud as they are close to the ground’s surface. In contrast, earthquakes usually occur several miles underground.
Croseismic booms are loud enough to be startling. However, they do not register on seismographs.
In recent months, the Midwest United States has experienced a brutal winter with record-setting snowfall and historically low temperatures. Scientists said the harsh conditions were a perfect combination for the unique phenomena.
Frost quakes are most evident if the ground has a chance to thaw between cold snaps. Last week, many states warmed up into the 40s before temperatures once again plunged below freezing. The brief thaw allowed moisture to collect in the ground before it refroze. The rapid weather changes may have led to more prominent booms.
Chuck Herron of St. Louis, Missouri, said it sounded like someone throwing snowballs across his roof. He said he “never heard anything like [that] before.” As reported by News Journal, the unexplained noises and lights prompted some residents to call 911.
Lisa Kammes of DeKalb, Illinois, had a similar experience. Kammes said she was preparing for bed when she heard several loud popping noises:
“The louder ones sounded like somebody was throwing snowballs at the house… It wasn’t the regular noise you hear when your house is creaking, blowing in the wind or ice is breaking.”
ABC News reports that the unexplained noises and lights were reported throughout Canada, Indiana, Michigan, Missouri, Ohio, and Wisconsin, within the last month. Thankfully as disturbing as they sound, frost quakes are not dangerous.
[Image via Shutterstock/Nordroden]