March 17, 2018 – Washington Co., WI – Washington County Sheriffs and West Bend Police received multiple calls overnight regarding loud booms between 10:30 p.m. and midnight.
According to the Washington County Lt. Tim Kemps they fielded about four calls and all appeared to be located close to Wallace Lake.
“We think it’s what’s known as frost quakes,” said Kemps.
The frost quakes sound like large booms.
According to the web page frostquake.org “Frost quakes,” also known as cryoseisms, are a natural phenomenon that occurs when extremely cold temperatures lead to sudden deep freezing of the ground, after it has been saturated with water. The Vermont Geological Survey defines a cryoseism as, “[a] major frost cracking of the top few feet of the ground, occurring during sub-zero cold snaps, which generates localized ground shaking and is often mistaken for an earthquake.” (1) Expansion that results during the process of freezing can lead to the buildup of explosive stress, which may result in fractures within the earth. Small cracks may be visible on the surface near where a cryoseism has occurred, and in some cases, shaking vibrations may also be felt within the vicinity of the frost quake, along with loud booms that sound similar to gunfire.”