From Philadelphia to Pittsburgh, Pennsylvanians may soon hear loud, explosive booms ringing through the night as temperatures drop. According to the Pennsylvania Department of Conservation and Natural Resources (DCNR), these startling sounds are most likely frost quakes, which are sudden cracking events caused by frozen ground splitting under extreme pressure.
Frost quakes, also known technically as cryoseisms, occur when rain or melting snow seeps into the ground and freezes too quickly during an arctic cold spell. As the water expands into ice, it exerts enormous stress, causing the soil or rock to fracture and release energy with a loud, thunderous crack.
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Meteorologists say this week’s weather pattern — gentle rain followed by a dramatic drop into the teens — is optimal for much of the state. Areas with low snow cover, such as portions of eastern and southwestern Pennsylvania, are particularly vulnerable since snow generally protects the ground from deep freezing.
Frost quakes usually happen between midnight and sunrise, when temperatures are lowest. While the events are fleeting and rarely harmful, they can shake homes and occasionally cause minor cracks in pavement or driveways.
To lessen the possibility of a hard freeze, experts recommend eliminating standing water and ensuring appropriate yard drainage.
