Loud booms and vibrations have recently been startling people in the night across the American Midwest. In central Ohio, police received calls reporting what sounded like gun shots or explosions.
The key to the mystery of these noises was a rapid swing in temperature. The Midwest has endured a prolonged freeze since Christmas, with heavy snowfalls, but a sudden thaw followed the arrival of a mass of warm air, then there was another freeze. This probably caused frost quakes, also called ice quakes, scientifically known as cryoseisms.
The phenomenon is created when the ground freezes following a rapid and extreme drop in temperature. The water deep down in the earth freezes then expands, and can cause the ground to crack very suddenly and explosively — creating a loud boom, a cracking sound or making the ground vibrate. Frost quakes tend to strike in the coldest time of the night between midnight and dawn, when they can jolt people out of their sleep.
“Almost sounds like a gunshot. When you hear them it sounds like something is hitting your house. It’s a really strong phenomenon,” says the meteorologist Mike Ryan of the National Weather Service in Indianapolis.
The vibrations from frost quakes do not normally travel far, although anyone standing on or near a frost quake can feel the ground shaking under their feet. Even though frost quakes can sound very dramatic, they rarely cause damage, although occasionally they lead to small cracks in the ground.
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Mysterious booms and bangs have also been heard recently in Colerain, Ohio, and were even accompanied by flashes of light. “I noticed out the window what seemed like a flash of light. The entire laundry room just kind of like shook,” the Colerain resident Alexis Makstaller said. The lights may be created by electrical changes that happen in rocks when they get squeezed during ice quakes. A similar phenomenon has sometimes been reported during earthquakes.