In the U.S. we are just exiting a period of bone chilling polar vortex temperatures and a lot of people are getting the shakes due to the cold. The Jacob Sheep don’t care.
No, I am not talking about shivers because they left off their gloves, I mean actual shaking ground along with weird popping or banging noises.
Having the ground shake under your feet can be very unsettling, especially in places like Chicago, Ohio, or central Pennsylvania which are not seismically active like California.
This is especially upsetting when the shaking ground is accompanied by a loud boom or bang.
USGS – Not Detected
A quick call to the USGS told me that they don’t even detect these ground shaking events because they occur within a few inches or a couple feet at most below the surface and sophisticated seismic detectors used by the United States Geologic Service don’t “see” these events.
Cryoseism or frost quakes are actual events and not just imaginary. The cause is very quick freezing of water in the ground. Normally winter strikes relatively slowly but this year in the northeast US we had a very mild winter and the ground was barely frozen in many places.
Given a light surface freezing and lots of moisture in the ground due to rain or melting snow combined with a very fast and deep drop of temperature from a polar vortex event the water freezes so quickly that it pushes dirt away fast enough to produce shaking and even strange sounds.
Water, of course, except in science fiction stories about Ice 9, expands as water freezes which is why ponds get ice on the surface while the fish at the bottom are still swimming around.
Frost Quakes – Fast Expansion
Frost quakes are due to this fast expansion of water turning into a larger volume of ice.
So, that’s it, frost quakes ARE REAL, but they are minor surface events which pose no threat to humans or animals and they are not indications that there are going to be more or larger events.