frost-quake-473x315I am working this week in Baraboo WI, where it has been way below freezing for days…and I might add, a tad cold for this California girl.  I happened to notice numerous articles in the midwest newspapers about “Frost Quakes.”  Never heard of that before!

“Frost Quakes,” technically known as cryoseism, have been reported in Missouri and across Midwestern states in this particularly cold winter. Swings in temperature lead to frost quakes, which happens when moisture in the ground suddenly freezes and expands.

If conditions are “just right”, the soil or bedrock breaks like a brittle frozen pipe, generating mysterious noises that range from an earthquake-like rumble to sharp cracking sounds sometimes mistaken for falling trees. This winter has been ripe for these frost quakes. Temperatures have been frigid, but occasional warm-ups have allowed for thawing. And the temperature swings have sometimes been abrupt.

Some people compared the noise to a sonic boom that rattles windows. Others described it as sounding like “somebody banging on their house.”  Some people also report light flashes that are believed to come from electrical changes that occur when the freezing compresses rocks. Frost quakes were reported last month in Missouri, Indiana, Michigan, Ohio, Illinois, Wisconsin and Canada.

This was my morning wake up temperature today in Baraboo...yikes!
This was my morning wake up temperature today in Baraboo…yikes!

Tremors typically occur a mile or two underground. Frost quakes are near the surface and do not show up on seismographs. These motions are shallow, but because they do not penetrate deep within the earth so the magnitude will not be large. As the rock moves, it generates sound waves and the ground motion.”

Damage is rare but homeowners who experience a frost quake should check for foundation cracks and watch for damage to water and natural gas lines.

http://www.csmonitor.com/Environment/Latest-News-Wires/2014/0206/Frost-quakes-cause-strange-sounds-light-flashes-in-frigid-Midwest