"Around 11 p.m. Christmas Eve, people reported hearing a loud “boom” in Toronto, Newmarket, Aurora, Belleville, Richmond Hill, and Sutton. Not only was the boom heard, but it rattled houses, leaving many to believe that a tree had fallen on their rooftop...
The most likely explanation is that it was a cryoseism, also known as a frost quake.
Cyroseisms are rare, localized seismic events that occur when a sudden drop in temperature freezes the groundwater, which then expands and cracks the soil and rock. The crack will release a sudden burst of explosive energy, resulting in a loud noise and the shaking of the ground. They usually occur between midnight and dawn."Addendum: recent occurrences here in Wisconsin:
The series of explosion-like sounds rattled residents from Waupun, Campbellsport and elsewhere Tuesday and sent Fond du Lac County sheriff's deputies out looking for a cause. Geologists say the booms were likely a phenomenon commonly known as an ice quake