A 3.2 magnitude quake was felt in the Muswellbrook area about 1.10am today with another 2.5 one felt about 2.30am.
Geoscience Australia seismologist Hadi Ghasemi told Nine’s Weekend Today there may be more aftershocks throughout the day.
“Generally speaking, the largest aftershocks tend to occur at the earliest stages of the sequence,” he said.
“As the time goes by, the frequency of the aftershocks start to decay too.”
In case of a more strong earthquake, Ghasemi advised residents to drop to their hands and knees and find cover under a sturdy shelter.
The tremors followed hours after the initial earthquake, which hit the town of Denman, near Muswellbrook, just after 12pm yesterday.
It was first reported as a magnitude 5 quake but has been downgraded to 4.7.
More than 3000 people across the state reported feeling tremors as far north as Coffs Harbour and as far south as Canberra.
Ghasemi said this quake was a “moderate” one.
“But, having said that, it is powerful enough to generate seismic waves, travelling a distance,” he said.
“We used records from thousands of kilometres away to locate the event.”
The earthquake in the region can be explained by the typically seismically-active coastline, that usually affects New South Wales, Victoria and Perth.
It’s understood the quake hit directly underneath BHP’s Mt Arthur Coal mine.
A few miners suffered minor injuries from falling items, but no one was seriously hurt, a company spokesperson said.
No other injuries in the state were reported.
Muswellbrook South Public School, which is close to the quake’s epicentre, was forced to evacuate.
SES teams in the area said the earthquake broke the windows at the council depot and damaged multiple homes, some which had collapsed chimneys.
Thousands more in the surrounding suburbs reported power outages to Ausgrid.
