Hello
everyone! On last Friday, my girlfriend and I heard a loud bang sound
and didn't know if someone was getting killed outside or something.
Kaylee saw nothing, so we took our question to facebook, where we
both learned there is something called a frost quake which is usually
the culprit for mysterious booms in the winter. So today I learned
about frost quakes.
Frost
quakes are also called cryoseisms. It's something that happens when
the extreme cold brings an unexpected freeze where the soil expands.
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.
Not
big enough to be picked up by a seisomgraph, frost quakes are
therefor hard to prove. They aren't particularly loud and the
farthest you will hear them is at about 300 feet. The shaking they
cause is also minor and never causes damage. Record cold temperatures
in 2013 caused more research to be done concerning these frost quakes
and climate change. The results were that we have been having more
frost quakes along with the rising temperatures.
As
recently as January 4th,
2018, York County experienced frost quakes. Jeri Jones is a
geologist who has been studying for thirty-eight years. He's been
taking reports of frost quakes from all areas of York County for the
past four years. He says the quakes always happen in the first
coldest spell of winter. The most recent report he received was
Tuesday morning in Monaghan Township. Several neighbors reported the
sound of a boom and because they were close neighbors, it likely was
a frost quake. Because York County is mostly frozen already, he
doesn't expect more quakes in that area. Sometimes when a quake
happens you can actually see the crack in the snow, seen here.
Sources :
Frost Quake.org 2015 What is a Frost Quake?
Zelko, Abbey 2018 1,4 What's a frost quake? The phenomenon could be the source of recent booms in York County
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