OceanaGold’s Waihi Martha open cut mine’s northern wall has collapsed.
The wall slip occurred yesterday, sending around two million tonnes of rock tumbling into the pit.
Oceanagold spokesperson Kit Wilson said the incident was not unexpected, according to the NZ Herald.
The miner has been monitoring instability on the north wall since November last year – when it bought the mine from Newmont – after the site registered a small wall slip in April last year.
“We have employed a range of monitoring systems to analyse the rock movement since we took over the mine six months ago, which has also allowed us to make precise measurements of the rock face and anticipate this sort of event,” Wilson said.
“Last week we advised the community that we believed there would be an event of this nature over the next few days, possibly on Anzac Day, including through Facebook posts, but we were one day out.”
This latest event is likely to push back the re-opening of the mine.
According to local radio station GoldFM, geotechnicians are on site assessing the collapse, while all work on the construction of a new haul road has ceased.