One Waihi resident who witnessed a large rock fall at Martha open pit gold mine described the sound as like a series of bombs going off and is now concerned more rocks may come down.
An estimated two million tonnes of rock and rubble collapsed from the north wall of the Waihi mine early on Tuesday further delaying plans to re-enter the mine.
Oceanagold senior community advisor Kit Wilson said the slip was not unexpected.
Jennifer Horgan, a social worker at Waihi Resource Centre, said she was returning from her walk along the fenced-off pit rim about 7.30am on Tuesday when she saw rocks coming down.
"I was almost back at the pump house and saw the mine rescue team standing there watching the slip. I was just about to leave when I heard an almighty explosion.