A magnitude 4.8 earthquake has rattled New South Wales.

The epicentre was in the Upper Hunter Valley, 250 kilometres north-west of Sydney.

The quake – initially identified as a magnitude 5.0 – hit just before midday and was felt in the Upper and Lower Hunter, the Central Coast and Lake Macquarie, Dubbo and Port Stephens.

Geoscience Australia said the epicentre was in Wollemi National Park.

On social media residents have reported their homes shaking, furniture moving and windows rattling.

Beryl Hartin from Muswellbrook was among them and said she was too scared to move.

"There was this boom and the whole house and the front fell off the air conditioner," she said.

"I wasn't game to move because I didn't know what else would fall down.

"My legs are still like jelly and I've got a neighbour here who's exactly the same.

Tom Alsleven was at work at the Royal Hotel in Muswellbrook when the quake hit.

"I was just in the bar making a few coffees for the kitchen staff and then we thought there must have been a truck hitting the building," he said.

"Everyone was just shaken up about it, but went outside and checked everyone was safe … not too much damage at the moment.

"We've had about two or three phone calls now asking if we're still open."

Brooklyn Nicholson lives in an apartment tower in Forster on the Mid North Coast and said the complex shook.

"I was like, 'Am I like going through an earthquake right now?'" she said.

Jenny Furner was at the Gunnedah Conservatorium at Gunnedah Town Hall and also got quite a scare.

"I thought the whole building was going to fall down around me," she said.

"It's an old building, so you could see the cracks in the wall shaking.

Geoscience Australia says thousands of people have reported feeling the tremor.

Police and  NSW Health say there are no reports of injuries.