Winter is coming, and it's never too early to start being afraid. One thing to fear in the coming season is ice earthquakes. They're called cryoseisms, and they are what happens when the weather heats up and cools off too often and too much.
A cryoseism happens when a winter season warms up and cools down too much. It's helped along if, during a warm spell, there's a shower of rain instead of snow. The water runs down between cracks in the ice. It can slowly leak far down into frozen ground and collect in large deposits. If there is enough water, and the temperature stays high, the water remains liquid, slowly building up until it fills all the cracks or open spaces in the ice.
Then the temperature drops and the water freezes. Occasionally it freezes very quickly indeed. As it freezes, it expands, pushing the ice, rock, and whatever else is around it apart. Freezing water can split stone, even if there's just a bit of it. A little cryoseism confines itself to making a loud noise, like a sonic boom, as it splits apart the ground around it. Enough water suddenly made ice can make make the ground shudder, shake multiple houses, and rip apart foundations. The ice makes an "earthquake."
Image: McKay Savage.