Just before noon, the Manning River Times received reports from residents in the Pampoolah, Glenthorne and Rainbow Flat areas of homes shaking with the sound of a boom and/or thunder, which lasted for about three seconds.

A post on the Times' Facebook page received more than 200 replies, with people confirming it had been felt at Moorland, Taree West, Hallidays Point/Diamond Beach, Harrington, Wingham, Tinonee, Koorainghat, Old Bar, Wallabi Point, Black Head, Ghinni Ghinni, Taree, Cundletown, Coopernook, Lansdowne, Chatham, Oxley Island, Bohnock, Cedar Party, Failford and Forster.

Others said while they didn't feel anything they did hear a sound that they thought was thunder, while others heard a loud crack.

An inquiry made to Geoscience Australia has not been able to confirm the cause of the tremor and rumbling sounds.

A spokesperson said some time was spent investigating the reports and looked "far, deep and wide" but did not have enough information to say whether it was an earthquake or the tremor and sounds were caused by something else.

"We can't categorically say yes or no that it was a naturally occurring earthquake. I could be something else."

The spokesperson said it isn't out of the "realm of possibility" that it may have been an aftershock as it is close enough to the 2.8 magnitude earthquake which struck east of Harrington in late August.

"But I can't say yes or no."

He said there are a number of other scenarios that could elicit the same potential effects of an earthquake including shaking houses, thunder and loud noises.

These could include strong weather patterns, a sonic boom, a mine explosion or an above ground explosion.

He said if the tremor felt on September 8 was an earthquake, it was too small for its seismic stations.