Earthquake damages buildings near site of proposed nuclear plant

A magnitude 4.7 earthquake struck near Muswellbrook just after midday on Friday, a few kilometres from the site where the Coalition has pledged to build a nuclear power plant, damaging some buildings in the town and sending tremors as far away as Sydney.

The State Emergency Services were called to help some people who suffered damage to their homes and businesses in Muswellbrook, but there were no reports of serious injuries.

A Geoscience Australia map showing the location of people who reported feeling tremors from the Muswellbrook quake.

Some buildings in Muswellbrook’s CBD had broken windows, fallen chimneys and stock spilling off shelves, locals said. At least two public schools were evacuated, and the local power grid was knocked until 2.30pm.

“It was quite alarming, we certainly felt it within the building,” said Muswellbrook Shire Council’s general manager Derek Finnigan. “It went for about 15 seconds I suppose, but it seemed longer of course.”

“We are assessing reports of minor damage to buildings in the community, some private structures in the CBD.”

Stock on the floor of the Mitre 10 in Muswellbrook after the quake struck at 12.01pm on Friday.

Tremors were felt in a large radius around the quake’s epicentre at Denman, just south of Muswellbrook, from southern Sydney to Coffs Harbour on the Mid North Coast.

About 2400 people contacted Geoscience Australia to report that they had felt the quake which struck at 12.01pm, senior seismologist Hadi Ghasemi said.

“That is a very large number,” he said. “The earthquake itself was of a decent size and at a depth of 10 kilometres it was quite shallow, so it’s not surprising that it was widely felt.”

Ghasemi said fault lines run near the quake’s epicentre, and these had probably been triggered by stress building up as Australia’s continental plate nudges slowly north-east at a pace of about seven centimetres per year.

“There are existing cracks and weaknesses in the rock in this area, so it is a place where you might expect stress to build up,” he said.

The quake’s epicentre was a few kilometres west of Lake Liddell, where the federal Coalition plans to build a nuclear power plant if elected.

Nuclear facilities can be designed to withstand quakes of magnitude 4.8 and above, according to the World Nuclear Association and studies prepared by the Australian Nuclear Science and Technology Organisation for the Lucas Heights reactor in southern Sydney. However, hardening nuclear facilities against large quakes would add to the overall cost of building them.

The quake’s epicentre was also close to four large coal mines which use explosives that can cause small seismic effects. Mines have been known to trigger larger earthquakes, but Ghasemi said this was unlikely to have been the case on Friday.

The decommissioned Liddell coal-fired power station, which is slated for a nuclear reactor site under the Coalition’s plans.Credit: Janie Barrett

“It is known that mines can induce earthquakes but looking at the seismicity of the region there are natural fault lines and a history of quakes,” he said.

“My opinion is that it’s unlikely given the size and depth of this quake that it was related to mining.”

The earthquake took place about five kilometres underground - relatively shallow for a quake of that magnitude.

It was the largest earthquake to hit the region in over two decades. The Newcastle quake of 1989, which claimed 13 lives, was 5.6 magnitude and caused extensive damage in central areas of the city.

Workers at BHP’s Mount Arthur coal mine, which is directly above the epicentre, proceeded with planned mine explosions on Friday afternoon after the quake had struck.

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