Around two million tonnes of rock has slipped at a gold mine in Waihi.
No one was working in the Martha open pit gold mine at the time and there were no injuries.
OceanaGold spokesperson Kit Wilson says the slip was not a surprise, and they have been monitoring the wall since a slip one year ago.
"We advised the local community late last week that we believed there would be an event of this nature over the next few days."
Locals may have heard the slip, but Mr Wilson says there was no danger to them at any time.
"While this most recent event was not unexpected, it will require us to modify our plans for re-entry into the open pit. Our plan was always to resume work in the mine if this could be done safely. That plan has not changed, but it may take a while longer."
There is still movement being detected at the mine, and further rock fall is expected, however on a much smaller scale.