Earthquake rattles regional Victoria after blasting incident at Agnico Eagle’s Fosterville gold mine
A mine-induced earthquake following underground blasting activities at Agnico Eagle Mines’ Fosterville gold development has rattled a cluster of towns in regional Victoria.
The 3.5-magnitude seismic event was felt in the early hours of yesterday morning by residents north-east of Bendigo shortly after activities commenced.
The epicentre of the quake was reported to have occurred at 6.40am in the Wellsford State Forest, about 20 kilometres from Bendigo.
Production firing
Fosterville environment and community manager Will Wettenhall said staff were working at the site when the latest quake happened.
“It occurred soon after production firing,” he said.
Production firing – or blasting – is an essential part of the gold mining process and can create ground vibrations that may be felt by residents in surrounding areas.
Agnico keeps track of ground vibrations using a network of blast monitors (or geophones) installed on the surface of its open-pit and underground operations to maintain compliance with local limits.
“The mechanisms are similar to an earthquake,” Mr Wettenhall explained, “however, they are related to our mining activities.”
No damage expected
Government agency Geoscience Australia received 37 felt reports from residents in and around the Bendigo area, with six more from people on the outskirts of Melbourne.
However, it was not anticipating any further tremors.
“The shaking associated with an earthquake of this size would be relatively short-lived and would not be expected to cause any damage,” a spokesman said.
“Often, with earthquakes of this size, people report hearing them more than they feel the shaking because they are quite short.”
Common occurrence
This week’s earthquake is the latest in a series of mine-induced events at Fosterville—the second of its kind recorded in the past seven days, with another smaller 2.3 magnitude quake felt on 1 November.
In July, the mine registered a 2.5 magnitude earthquake located almost 1km below the surface and 88m above the nearest underground mine workings.
80 underground workers were evacuated in April 2022, after Fosterville was rocked by another 2.5 magnitude quake—the largest seismic event since monitoring technology was installed in 2019.
“We recognise that such occurrences can be concerning for local residents, and we encourage those impacted to reach out to us,” Agnico said at the time.
“We we want to assure [residents] that we have robust safety protocols in place.”
Gold production
The 1.68 million-ounce Fosterville mine began operations in 2005, initially producing gold from near-surface, low-grade mineralisation.
High-grade visible gold intercepted at depth led to the discovery of the Eagle Zone in 2015, while the ultra-high-grade Swan Zone was identified in 2016, eventually transforming Fosterville into one of the world’s richest gold mines.
Fosterville produced 277,694oz of gold in 2023, and is operating to a 2024 production guidance of 210,000oz.