Earthquake activity across Orange revealed: Data shows our region's tremor hot spot

Orange has recorded a staggering amount of earthquakes in the last decade, with our largest shock in that time sending Cadia - Australia's largest gold mine - into lockdown.

That tremor, recorded as a 4.3 magnitude earthquake, hit about 25 kilometres south west of Orange in April, 2017.

At the time, Cadia East was closed for around six hours and, as per procedure, personnel working in the underground operations in the gold mine were moved to refuge chambers, or safe areas.

The quake occurred in the proximity of Four Mile Creek Road, which is a little hotbed for earth tremors around Orange.

It is just one of 139 earthquakes recorded within a 100km radius of the Orange CBD in the last decade.

Our last episode was on January 9, 2023 not far from Molong and reached a magnitude of 2.6.

Those living in the area may have felt that tremor, too, with most quakes around the level 3 magnitude normally felt. The vibrations are often likened to the passing of a truck. Although, at that level, it's highly unlikely any damage is caused.

The bulk of our region's tremors, though, are recorded in what Geoscience Australia Senior Seismologist Professor Phil Cummins is calling a "cluster" south west of the city, not far from Mount Canobolas.

Other notable recent quakes include a magnitude 2.4 event about 10 kilometres west of Orange on May 4, 2021 and a magnitude 2.5 event about 10 kilometres northwest of Orange on February 14, 2020.

He said the smallest detected around Orange was a magnitude 1.3 event, and there has likely been a number of similar sized events that have completely slipped under the radar too.

"Geoscience Australia should be able to detect any earthquakes larger then magnitude 3; there may be more smaller than 3 that Geoscience Australia either did not detect or could not estimate the magnitude and location for. None of these should have caused any significant damage," Dr Cummins said.

Although relatively small on the scale of things, the energy released from tremors around that 2.5 magnitude are equivalent to an explosion involving upwards of 600kg of TNT.

Dr Cummins said these earthquakes occur in response to the gradual build-up of stress within the Australian Plate.

He said that stress can be transmitted from the colliding of a number of factors, some as far away as the Himalayas.

"(The stresses are) mainly transmitted from the plate boundaries, particularly where the continental lithosphere of the composite Indo-Australian Plate is colliding with continental lithosphere in New Zealand, Papua New Guinea and the Himalayas," he said.

Looking further back, over the past century, Geoscience Australia has recorded 589 earthquakes within 100 kilometres of Orange

Of these, 65 events were above magnitude 3, with the largest being about magnitude 4.6 in 1947, about 20 kilometres southwest of Cowra.

That Cowra area, too, appears to be a hive for tectonic activity, with Boorowa recording 1080 quakes with a magnitude of above 2 in the past 100 years.

WHAT DO YOU THINK? We've made it a whole lot easier for you to have your say. Our new comment platform requires only one log-in to access articles and to join the discussion on the Central Western Daily website. Find out how to register so you can enjoy civil, friendly and engaging discussions. Sign up for a subscription here.