Cold Facts: Frost quake! — a boom in the night

Winter is upon us and the cold is here to last, with double-digit negative temperatures forecasted for the next week. Is there a bright side to any of this? Not really. But we offer the tiniest of silver linings! To accompany this cold snap, we’re running a short-term daily feature: Cold Facts. 
Long spells of deep cold bring frost quakes, or cryoseisms. Here’s how they work:
Water saturates the ground and then deep cold makes it freeze. The water expands as it freezes, and pres