Anchorage, AK – Alaskans from Anchorage to Fairbanks may soon hear sharp booms echoing through the night — but they’re not earthquakes. According to the Alaska Earthquake Center, these sudden noises are often frost quakes or cryoseisms — ground-cracking events caused when frozen soil suddenly fractures under pressure.
Unlike typical seismic activity, frost quakes occur close to the surface. They form when water from melting snow or rain seeps into the soil and freezes too quickly. As that trapped moisture expands into ice, it exerts tremendous force until the ground splits apart, releasing a loud, thunder-like crack that can startle residents and even shake nearby homes.
Meteorologists say Alaska’s alternating warm and cold spells this month — with daytime thawing and subzero nights — create ideal frost-quake conditions. The risk is highest in Southcentral and Interior Alaska, where shallow groundwater and temperature swings often combine to trigger these mini seismic pops.
Frost quakes usually occur between midnight and dawn, when the cold is most intense. While harmless in most cases, they can cause small cracks in pavement or frost heaves in yards.
Experts say they’re a reminder of Alaska’s extreme freeze-thaw environment — and of the dynamic relationship between water, rock, and cold.
So if you’re awakened by a loud boom on a calm, icy night from Anchorage to Fairbanks, it’s not tectonic movement — it’s Alaska’s frozen ground cracking under winter’s power.
