PREISSAC, Que. - The manager of a Quebec gold mine where nine people were trapped for 18 hours says the section at the heart of the incident may not reopen.
A survey will need to be done with consultants and engineers to determine whether the area is safe, Sylvain Lehoux said Wednesday.
"It can take lots of time, but we want to make sure that everything is OK when we get back — if we get back there," he said in an interview.
The miners were rescued Tuesday by a tunnelling machine at the IAMGOLD Corp. (TSX:IMG) facility in Preissac in the Abitibi-Temiscamingue region in northwestern Quebec.
They became trapped more than one kilometre underground after a wall moved because of seismic activity in the area.
Lehoux said the miners were "really, really tired" when they returned to the surface.
"No injuries: that was our concern, so we are happy to say they are in good shape," he added.
Lehoux said company equipment recorded seismic measurements of 1.2 and 1.7 on the Richter scale on Tuesday morning.
"They happen sometimes and that's why we're installing more and equipment to predict them," he said.
"It's not really an earthquake, it's really a seismic event which is sometimes related to excavation underground or a 'rock blast'."
He noted that in January several miners were also caught in an area not far from the location of Tuesday's wall collapse.
Marc Thibodeau, a union spokesman in the region, said an inquiry will determine whether there is a problem in the area.
"Was it an earthquake or pressure on the rocks because we were mining in the sector?," he said Wednesday.
IAMGOLD only started commercial production at the Quebec facility in July 2014.
Lehoux said the mine is located on what he described as the Cadillac fault and any movement can cause an earthquake.
"Yes, definitely, and that's why you have to be vigilant," he said.
An expert with the Quebec Natural Resources Department says the fault measures between 300 and 350 kilometres in length, while Stephen Halchuk, a seismologist with the Geological Survey of Canada, noted in an email that damage from an earthquake will vary depending on its magnitude.
"In Eastern Canada, in general, a magnitude-five-or-larger earthquake is required before we begin to experience significant damage to structures," he wrote.
— With files from Peter Rakobowchuk in Montreal