The US Geological Survey detected the earthquake, about 35km west-southwest of the mining town of Amos at a depth of 3.5km.

Iamgold said employees were brought to the surface safely and authorities had been notified while the cause of the quake was being studied.

The company is assessing a recovery plan and expects to provide an update when it discloses September-quarter results later this week.

Westwood production was suspended in late March due to COVID-19, and the operation restarted mid-April. For this reason, Iamgold has lowered the mine's full-year production guidance to 85,000-100,000oz from 90,000-110,000oz previously.

In August the company cut Westwood reserves by 48% and outlined a "cautious" approach to a long-term plan for the seismically-compromised operation. The company has been reviewing Westwood and last year recognised a US$395 million impairment owing to the mine operating at reduced capacity after an earthquake late in 2018. 

Iamgold shares (TSX:IMG) are down 2.2% over the past 12 months at C$4.90, after achieving a 12-month high of $7.07 late in July. The company has a market capitalisation of $2.32 billion (US$1.75 billion).