Mosaic (NYSE: MOS) says a magnitude 3.4 earthquake near its Esterhazy potash operations in Saskatchewan on Tuesday is not expected to disrupt production, despite striking an area previously affected by mining-induced seismic activity.
The earthquake occurred at 7:04 a.m. CST on Nov. 3, about nine kilometres east-northeast of Esterhazy, according to Natural Resources Canada’s Earthquakes Canada website. Workers felt the tremor in a mined-out section of the K3 underground mine, but all employees were accounted for and safety inspections have been completed, the company said.
“Mining induced seismic activity in this area is common, and our facilities are engineered with seismic loading in mind,” Mosaic said. “While the recent event occurred far from current mining areas and presents no immediate safety concerns, we continue to advance our understanding of the geological properties of the K3 ore body and will work with external experts to review seismic activity.”
The incident comes as Mosaic grapples with geological challenges at Esterhazy that have already weighed on potash production. In third-quarter results released the same day, the US fertilizer producer said lower-than-expected ore grades at the mine contributed to reduced output and a downward revision to its full-year production forecast.
Seismic history
Earthquakes Canada classified Tuesday’s tremor as a “suspected mining-induced event.” The region experienced three earthquakes in 2025, including two within three months, which the federal agency also linked to possible mining activity.
The latest event follows a fatal accident at Esterhazy’s K3 mine late last year, when a worker died following an underground collapse.
Esterhazy is one of Mosaic’s key potash production centres, with a nameplate capacity of 7.8 million tonnes annually. The complex comprises the K1, K2 and K3 mines, with construction of K3 completed in 2022.
About 1,200 people work above and below ground at the site, according to the company’s website.
Production pressures
News of the seismic event came on the same day Mosaic reported a third-quarter net loss of $72 million, or 23¢ per share, compared with net income of $411 million, or $1.29 per share, a year earlier. Revenue fell about 10% to $3.1 billion, while adjusted earnings before interest, taxes, depreciation and amortization (EBITDA) declined to $324 million from $806 million.
The company’s potash division generated $643 million in sales, down from $695 million a year earlier, as sales volumes slipped to 2.1 million tonnes from 2.3 million tonnes. Segment adjusted EBITDA fell to $284 million from $329 million.
Mosaic said abnormal geological conditions at Esterhazy reduced ore grades during the quarter, prompting it to lower its 2026 potash production forecast to 8.6 million tonnes. The company expects the grade issues to be temporary and continues to target annual output exceeding 9 million tonnes over the longer term.
Despite the challenges, potash production costs improved from the previous quarter, falling to $73 per tonne from $84 as higher operating rates at Esterhazy and Colonsay helped spread fixed costs across greater output.
Mosaic expects fourth-quarter potash sales of 2.3 million to 2.6 million tonnes, with realized mine-gate prices ranging from $255 to $275 per tonne.
The company said it would continue studying the geological properties of the K3 ore body with external experts, as it works to manage seismic activity and improve production performance at Esterhazy.
Source: https://www.mining.com/earthquake-rattles-mosaic-potash-mine-in-saskatchewan/
