The so-called ice quakes surprised several localities in the central and eastern United States during the intense extreme cold wave that has hit the country in recent days.
Loud booms and vibrations similar to explosions alerted residents, who reported experiences akin to a quake.
The phenomenon has a meteorological explanation: it involves cryoseisms, events that occur when the frozen ground suddenly cracks due to sharp temperature drops.
During Monday night, areas from northern Tennessee to central Kentucky recorded these events.
Reports emerged following a winter storm that left over 30 fatalities in the country.
How do ice quakes occur?
Evan Webb, a meteorologist with the National Weather Service (NWS) in Kentucky, explained that the process originates “when the ground becomes saturated due to rain or freezing rain, which manages to penetrate the unfrozen ground, seeping in until it saturates it.”
Ice quakes develop under a specific sequence of conditions. First, the ground becomes saturated previously by rain or freezing rain.
Then, water manages to seep into layers of earth that are not yet frozen.
Subsequently, a rapid temperature drop occurs. Finally, the trapped moisture freezes and expands abruptly.
According to Webb, “this causes small cracks or fractures, and that’s what generates those loud booms or ‘pops’ that people have been hearing recently.”
This phenomenon usually occurs mainly during the night and can cause the falling of trees or vibrations similar to a conventional quake.
The polar vortex behind the extreme cold
The cause behind these unusual temperatures is the displacement of the polar vortex. This mass of cold air, which normally resides over the North Pole, moved to lower latitudes.
The phenomenon brought polar air to states unaccustomed to this climate, such as Kentucky, Tennessee, and even Florida, where subzero temperatures were expected in cities like Miami.
The impact of this winter system was severe: at least 34 deaths were reported by last Tuesday. More than half a million homes lost access to electricity.
Wind chills dropped below -20 degrees Celsius in some regions.
“It’s not paranormal”: the call for calm
In response to reports from citizens frightened by noises similar to gunshots or explosions, regional offices of the NWS issued clarifying notices about the ice quakes.
In Louisville, Kentucky, the weather service reported via social media that “those loud pops are not paranormal, they are cryoseisms!”
Despite the alarming nature of the sounds, experts clarified that ice quakes “are generally harmless” to people and structures.
However, the cold that causes them does pose a deadly risk.
Historical records of similar events, such as in January 2024, remind us of the dangers of these cold waves, which on that occasion claimed the lives of at least 40 people in states like Texas and Louisiana.
