As overnight temperatures in Toronto dipped to -20 C, many people again reported hearing loud booms, which CBC meteorologist Jay Scotland says was likely the result of a "frost quake."

Frost quakes, a rare phenomena that simulate earthquakes, rattled hundreds of residents Thursday in Darke and Miami counties in Ohio and Randolph County in Indiana, emergency management officials said.

His office has been getting calls from people having problems with grit and sand getting into their well water this winter. He said the theory is that the deep frost is setting off frost quakes — a shift in the ground similar to fractures on ice — which disturbs the seals of well casings, allowing silt to get into the pipe.