People are still trying to figure out what caused a loud boom earlier this week in Sudbury.
On Monday evening, a big bang rattled residences around 5:30pm.
That was about the same time Vale employees were pouring hot slag on the frozen ground.
Vale’s corporate affairs manager, Angie Robson, said it’s not unusual to hear a slag pop during extremely cold weather, but she said the company is investigating the incident because the sound was heard as far away as New Sudbury and Garson.
There is also speculation it could have been a frost quake, which happens when ice in the ground expands and causes cracks.
Earthquakes Canada said it can’t confirm if there was a frost quake, but it remains a possibility.