Recent seismic activity in Australia

Australians in parts of Victoria, New South Wales and the Northern Territory may have felt the earth move beneath their feet over the past several days, after a seismically active period across the country.

On Sunday morning, an earthquake of preliminary magnitude 5.1 was recorded near the Otway Ranges (previously referred to as Apollo Bay) in Victoria at 2.11am on 22 October. The earthquake was at a depth of around 10 kilometres. Just over 8,400 residents lodged a felt reports, from as far north as Bendigo and as far south as King Island. After review, the earthquake magnitude was revised to 4.7.

This event, or 'main shock’ was followed by five aftershocks measuring 2.5, 3.6, 2.5, 2.7 and 3.7 magnitude between 5:40am on 22 October and 1.17pm yesterday (24 October).

Aftershocks are common following any moderate-to-large earthquake and occur due to a redistribution of stress around a ruptured fault. Further shaking could be expected over the coming days, weeks and months.

Elsewhere in the country, a 3.6 magnitude earthquake was detected near Tennant Creek in the Northern Territory at 3.05am on 24 October. 10 people lodged a felt report for the quake, which had a depth of around one kilometre.

64 people lodged felt reports following a magnitude 2.6 earthquake near Cobargo in New South Wales around 9.32pm last night at a depth of around 10 kilometres.

A 4.0 magnitude earthquake was registered near Goodooga on the border of New South Wales and Queensland around 11.38pm, resulting in no felt reports at this time which is to be expected, as it is a very remote part of the country.

Finally, this morning three people lodged felt reports after a 2.6 magnitude earthquake with a depth of around 10 kilometres was detected around 12.45am today on Phillip Island.

Senior Seismologist Tanja Pejic said while there were earthquakes every day in Australia, most are not felt because of their low magnitude or because they sometimes occur far away from populated areas.

“On average, around 100 earthquakes of magnitude 3 or larger are recorded in Australia each year,” Ms Pejic said.

“Earthquakes in Australia, or intraplate earthquakes, can and do occur anywhere on the continent due to the movement of tectonic plates.

“Earthquakes above magnitude 5.0, such as the destructive 5.4 magnitude earthquake in Newcastle in 1989, occur in Australia approximately every one to two years.

“Approximately every 10 years, Australia experiences a potentially damaging earthquake of magnitude 6.0 or larger such as the Meckering earthquake in October 1968 and the off-shore Broome earthquake in 2019.

“Movements and interaction of the plates occur on time scales of hundreds of thousands of years. To measure changes in occurrence frequency of earthquakes in Australia, it is necessary to look at observation data over centuries, so it is not possible to say definitively whether there is an overall increase in seismicity in any one area in Australia.”

For more information on current earthquakes, visit http://earthquakes.ga.gov.au