Some residents on Montreal's West Island were shaken early Tuesday morning by a weather phenomenon known as a "frost quake."
Dollard-Des Ormeaux resident Samantha Koury was woken at around 2:30 a.m by two loud noises.
"It sounded like a really big bang, like something fell on the floor in the house. And then there was another loud bang like something fell on the roof," said Koury. "We literally felt a huge shaking of the floor."
The phenomenon — technically called a cryoseism — happens when water underground in caverns and pockets freezes very quickly, putting pressure on the surrounding earth and rock.
“The pressure grows until it breaks out and is released. That's the big boom. It's all that energy,” said David Phillips, a senior climatologist at Environment Canada.
- GRAPHIC | The science of frost quakes
Phillips says a "frost quake" could crack the ground and cause it to shake — feeling very similar to an earthquake.
He says a similar event can also happen when water collects on flat roofs.
"It will freeze expand and then crack with a boom," said Phillips.
Some West Islanders took to Twitter reporting hearing a loud boom overnight.
Learn more about cryoseisms tomorrow on CBC radio's Daybreak Montreal Wednesday at 6:40 a.m.