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Mine hit by ‘tremor’

Friday, 19th December, 2014

By Andrew Robertson

A large “seismic event” at the southern-most end of Perilya’s lease on Wednesday night has damaged a disused underground drive.

But the company said the tremor, which shook houses in the area, was not necessarily linked to an underground firing that was set off only minutes earlier.

Mine manager Bruce Byrne told the BDT an internal monitoring system picked up the event which happened at the Southern Cross area of the mine on the 21 level.

Shortly after it hit, one shaken-up Railwaytown resident told the BDT that it felt like “a big boot” rather than a firing.

“We did have a seismic event. It occurred shortly after (firing) at 6.45pm,” Mr Byrne said.

He said the area was not being worked but an exclusion zone was immediately declared to prevent anyone from entering the area for 12 hours.

The declaration lapsed at the start of day shift yesterday morning when senior geotechnical engineers and other senior staff inspected the zone and carried out a “re-entry”.

Mr Byrne said they reported that damage was limited to a redundant drive and that no working areas of the mine were affected.

“We have very high ground support standards and they held up very well.”

The affected drive would be closed off and filled in, he said.

Seismic events were registered daily at the mine but Mr Byrne said they were usually “small enough that you don’t feel them”.

“It was definitely larger than normal.” 

While it happened only minutes after a firing, Mr Byrne also suggested the two events were not necessarily linked.

“It’s difficult to say; we haven’t connected the two.”

Geoscience Australia also said it could not say whether the event was “naturally occurring” or not.

“We’ve recorded something which looks like a magnitude 2.6 earthquake, however, we can’t rule out that this recording was linked to mining activity,” a spokesman said. 

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