In the stillness of a chilly winter’s night, a “boom” echoes through the air, and a crack gashes the ground at your feet. The land shudders and trembles. Whoa! Was that an earthquake? An explosion from a mining accident? Maybe the apocalypse?
Nope. In scientific terms, you’ve just experienced a cryoseism. In other words: a frost quake.
Like an earthquake, a frost quake causes the ground to jolt and shake, producing seismic waves and even splitting stone. Unlike earthquakes, however, they are not true tectonic events. There are no tectonic plates, fault lines, or volcanoes involved. Instead, frost quakes start with a simple mixture of water and ground. The key ingredient? As their name implies, the catalyst of a frost quake is cold—sudden, bone-chilling cold.
First, water saturates the ground, perhaps from the melt of a recent snowfall. Then, the temperature drops quickly to sub-zero. A crust of ice forms at the soil’s surface. Like a cork that stops up fizzy champagne, the ice entraps the freezing groundwater below. As the groundwater freezes, it expands, pushing and stressing and straining the nearby rock and soil. It looks for an outlet but finds none. When the pressure becomes too much, the ground suddenly breaks under the stress. The resulting release of energy cracks the earth and causes an explosive “boom!”
Frost quakes typically occur at night, when the temperature drop is most severe. Unlike earthquakes, frost quakes are not potentially deadly—though they might shake your house and rattle your dishes, they won’t destroy buildings. Yet their cracks and booms offer a stark reminder of winter’s power.