A small earthquake near Cessnock on Tuesday morning was the fifteenth in the Hunter in the past four months.
The 2.7-magnitude quake was recorded off Sandy Creek Road, Quorrobolong at 2.30am Tuesday.
Ten days prior, a quake was detected off Thursbys Road, Congewai at 1.03am, measuring 2.1 on the Richter scale.
A quake measuring 2.4 on the Richter scale hit in the middle of Ellalong Lagoon at 12.43am on October 2.
These follow two small quakes within the same 20-kilometre radius last month – a 2.4-magnitude at 9.24pm on September 28, and a 2.6 at 10.05pm on September 20.
Four quakes were reported felt near Muswellbrook the week before that – a 2.3 at 11.19pm on September 15, and three the following morning between 8.44am and 8.47am.
Three small quakes (measuring between 2.1 and 2.4 on the Richter scale) were reported near Gresford shortly after 3am on August 27.
A 3.2-magnitude quake was felt in Muswellbrook on August 11, and quakes were reported in Muswellbrook and Jerrys Plains less than half an hour apart on July 18.
But the quakes’ proximity to the region’s coal mines could be no more than a coincidence.
Geoscience Australia duty seismologist Eddie Leask said a certain level of earthquakes occur on faults, and so do minerals.
He said mine blasting activity can give off a very different signal, one that’s “more distorted and messier” than earthquakes.
Mr Leask said earthquakes have been felt in the Hunter since the 1840s.
Cessnock-Kurri Greens member James Ryan said he was concerned by some research from the Seismological Society of America that has shown earthquakes can be caused or accentuated by underground coal mining.
The researchers studied how “fairly shallow underground coal mining” can cause earthquakes that, depending on their size, “might pose a ground-shaking hazard to nearby surface structures”.
But Mr Ryan said the impacts of coal mines in contributing to human-induced climate change was a far greater concern.
“The changing climate over the next 50 to 100 years is going to impact on the Hunter Valley, like elsewhere, particularly via warmer drier winters and more frequent severe storm events will potentially change our farming, fishing and lifestyle,” he said.