Cause of powerful early-morning earthquake near Melbourne

Activity at a mine near Bendigo is responsible for a powerful earthquake that struck early on Tuesday morning.

The magnitude 3.5 quake struck at 6.41am, about 45km northeast of Bendigo, near the town of Elmore, according to Geoscience Australia.

The Forestville gold mine near Bendigo, about 20 minutes from Elmore, said a ‘mine-induced seismic event’ had been recorded.

“We understand this was felt by many in the surrounding community,” the company, Victoria’s largest gold producer, said.

‘FGM is currently assessing the event and we will publish further details as soon as they are confirmed.’

Residents in Bendigo and as far away as Melbourne reported feeling minor tremors, but nothing comparable to Victoria’s largest recorded earthquake which occurred in September 2021 with a significant magnitude of 5.9.

That earthquake, which originated near Mansfield, caused building damage in Melbourne and was felt as far away as Canberra, Sydney and Adelaide.

There have been more than a dozen earthquakes of magnitude greater than three in the area since the 2021 event.

Aftershocks that occurred years or decades after the first earthquakes were common, Prof. Cummins said, and more could follow, seismologist Phil Cummins explained.

“It’s not unusual for large aftershocks to have their own aftershocks,” Prof Cummins said.

Although Australia did not have an active tectonic plate boundary like New Guinea or New Zealand, stress from other boundaries slowly built up into the interior of the plate, eventually causing faults to fail.

“They simply fail much less often than near tectonic plate boundaries, where strain rates are much greater,” he said.

The largest earthquake ever to hit Australia was a magnitude 6.6 earthquake that struck Tennant Creek in the Northern Territory in January 1988.

An average of 100 earthquakes of magnitude 3.0 or greater are recorded in Australia every year.

According to the Seismology Research Centre, an earthquake of magnitude close to 7.0 occurs somewhere in Australia about every 100 years.

“In active areas such as Japan, the Philippines or California, earthquakes of magnitude 7.0 occur every few years,” the report said.

‘Activity at these places is confined to a much smaller area than that of Australia, so a typical site could be within 50 km of a magnitude 7.0 event every 100 years.

‘Earthquakes of magnitude 8.0 and greater are called major earthquakes and normally only occur at plate boundaries

‘It’s unlikely this will ever happen in Australia. Earthquakes of magnitude 9.0 and larger will rupture fault lines over hundreds of kilometers, so they usually only occur in subduction zones such as along the west coast of South America or the southern coast of Alaska.’