Updated Feb. 7 at 8:30 a.m.
In a statement, Vale confirmed that a seismic event occurred at Garson Mine Wednesday evening at around 5:08 p.m.
"All employees have been accounted for and are safe. No employees were underground at the time," said the statement. "Once the affected area is deemed safe, we will assess for any damage that may have occurred as a result of the event."
Earthquakes Canada has confirmed that a 2.9 magnitude earthquake was recorded near Sudbury at 5:08 p.m. on Feb. 6.
The origin of the seismic activity was about 27 km east of Sudbury.
Reports of ground shaking and rumbling started circulating on social media shortly after 5 p.m. on Wednesday, and those reports weren't unfounded as a quake of that magnitude, in that proximity to the city, would certainly be felt.
"That magnitude is quite low and we wouldn't expect any damage done from that, but you would definitely feel it if you're in that area," said Allison Bent, seismologist with Earthquakes Canada.
According to Bent, any seismic activity with a recorded magnitude over 2.0 is generally enough to feel if you're in a close radius to the origin of the quake.
Eastern Canada does experience quakes like this every day, though most of them aren't felt.
"There's several like this every day in the eastern part of Canada, but at this size, if they occur in a remote area with no people within 100 km you wouldn't feel anything," said Bent.
This was in fact an earthquake and not a frost quake, which can occur when temperatures fluctuate and soil and rock crack when underground water freezes rapidly and expands.
"It was definitely not a frost quake," said Bent. "You guys do get those but the magnitude is generally low. This event showed the typical earthquake signal."
There was no recorded aftershock from the seismic event, and Bent says that is likely due to the relatively small magnitude of the initial quake.