The NSW State Emergency Service (SES) said it had received 11 calls related to minor residential damage and reports of minor infrastructure damage in nearby towns of Maitland and Muswellbrook.
The SES said dams in the area were unaffected.
Unverified social media posts showed stock knocked on the floor of a Muswellbrook hardware store and cracks in the wall of a house in the town, said to be caused by the quake.
UNSW geophysicist Stuart Clark said the quake was the biggest of six to hit the local area, a coal mining hub, in the past 50 years.
“It’s a little smaller than the Newcastle earthquake, and there was another one 5.3 [magnitude] in 1994,” associate professor Clark said.
“The cause is compressional forces across the continent but the trigger is potentially coal mining.”
He warned of aftershocks in the next two days, saying “there might be a cluster of aftershocks typically a little bit smaller than this one”.
“They don’t have to follow major earthquakes but they can.”
One resident of Muswellbrook, about 22km south of Denman, described the quake as much bigger than “just a tremor”.
“The whole house rattled, and then about half a minute later, it rattled again,” the woman said.
