A union official says workers at Newcrest’s Cadia Valley Operations have safety concerns following a spate of earthquakes in the region.
The national secretary of the Australian Workers’ Union Daniel Walton said the tailings dam wall breach on Friday followed two small earthquakes nearby the night before.
“A lot of workers are worried that the mine is not taking this activity seriously enough,” he said.
“They do have concerns about safety. The seismic activity that occurred on Thursday night was the fourth earthquake in the last 12 months.
“These quakes have ranged from 5.7 to 2.7 in magnitude.”
MAP: Where the earthquakes occurred ...
A spokeswoman for Newcrest said it was not clear what had caused the collapse.
“It may take some time before we are able to ascertain why this wall failure occurred,” she said.
“The safety of our people, the community in which we work, and are operation are our priority.”
A spokesman for Geoscience Australia [GA] said two separate quakes, 2.7 in magnitude, were recorded 10 seconds apart at 9.42pm on Thursday.
“The two earthquakes were about five and 10 kilometres from the tailings dam,” he said.
The spokesman said the depth of the quakes was unknown and the 10 kilometre depth listed on the GA website was “nominal.”
However he said a 10-kilometre depth was “generally regarded as a shallow earthquake.”
The safety of our people, the community in which we work, and are operation are our priority.Newcrest spokeswoman
The spokesman said it was unclear whether the quakes could have caused damage.
“Earthquakes of these magnitudes cause ground motions of low intensity that would not generally be expected to significantly damage any building built to Australian standards,” he said.
“However the potential for any particular earthquake to cause damage to a specific structure needs to be assessed by a geotechnical engineer.
“[About] 80 earthquakes have occurred in the Cadia region since 1962, with the vast majority [about 60] occurring in 2015-16.”