Australian media has reported the evacuation of workers from the Frog Leg mine, 20 kilometres west of Kalgoorlie-Boulder.

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The Mungari gold operation, which consists of the underground mine at Frog’s Leg. Image source ©Evolution Mining

While operations have returned to normal at the goldmine owned by Sydney-based Evolution Mining, a number of exclusion zones were set up to prevent workers from accessing certain parts of the mine.

Evolution Mining’s Chief Operating Officer, Bob Fulker, said the company noticed increased seismic activity on a ‘micro-seismic scale’, but production was not affected by the temporary closure and there was no damage.

“Seismic activity is a regular natural occurrence in the Goldfields, and we have sophisticated systems in place at our Mungari operations to record and manage it,” said Mr Fulker.

Mr Fulker said on Wednesday 16 October, an increase in minor seismic activity was recorded in the Frog's Leg underground mine — part of our Mungari operations — and as a precautionary measure the company decided to temporarily suspend operations in a small section of the underground operation.

According to a company statement, all other parts of the underground operation, including the decline, continued to operate as normal, with further two levels isolated later in the day due to the monitored activity.

“No increase in seismic activity has been recorded since this time and operations resumed in all areas last Thursday morning,” commented Mr Fulker.

The tremors were not big enough to be picked up by Geoscience Australia's monitoring equipment, but that is not unusual given most mine sites employ sensitive equipment to keep track of ground conditions.

The latest seismic activity comes after Evolution last year introduced new technology to improve safety at Frog's Leg, including 3D scanners mounted on underground drones to assesses ground support requirements.

Frog's Leg was discovered in 1999 and was mined as an open pit from 2004 until heading underground in August 2007.

The mine has produced close to one million ounces — the equivalent of about AU$2.2 billion at today's near-record gold price — and now extends about 750 metres below the surface.