Australia Weather News

A loud sound that shook buildings and rattled residents in north-west Victoria has authorities mystified.

Hundreds of residents in the Mildura region took to social media on Tuesday to report a "bang" or "boom" just after 2pm.

The noise was reportedly heard as far away as Boundary Bend, more than 100 kilometres from the region's centre.

Helen Jack was at her home in Mildura when she heard a bang and her house "shuddered".

"Initially I thought that perhaps I'd left the garage door up, as we have a boat in there, which we've got chain-locked to one of the posts … I thought maybe someone was hacking into the lock," she said.

Ms Jack said she then ran outside as it "felt like the vibration was on the roof".

Resident Andrew Kynaston was working at a house in Mildura when he heard the noise.

"I thought maybe they [the owner] had kicked the door," he said.

"There was quite a loud noise and the windows vibrated."

"You could see it in the glare of the sun, where the window moved."

'Surface explosion' likely, but where?

University of Melbourne research fellow and AuScope Subsurface Observatory manager Dan Sandiford said a "very clear, short-lived pulse" lasting about a second was recorded at 2.13pm on Tuesday at the Seismology Research Centre's Mildura station.

Dr Sandiford said the signal was more characteristic of an atmospheric or surface explosion than an earthquake.

"The only sources of big, naturally occurring atmospheric sound waves that I know of are meteors, lightning and volcanoes," he said.

But the sound was not picked up at stations in Renmark or Lake Boga and Dr Sandiford said an atmospheric blast near Mildura, such as one caused by a meteor, would probably be detected in those locations.

"It looks like an explosion," he said of a graphic reading of the event.

But Dr Sandiford said the sound was unlikely to be the result of a quarry blast, the "main sources" of explosions recorded at its stations in Australia. 

"Quarry blasts look a lot like earthquakes because they are generally a source of energy that occurs within the rock.

"It doesn't look like a quarry blast because we'd be expecting high frequency energy and we'd be expecting the signal to carry to Renmark."

The Country Fire Authority said it had no reports of fires or explosions at that time and Mildura Inspector Dave Rowe said there were no requests for a police response.

"From a policing point of view, we don't know [what the noise was]," he said.

Not of extraterrestrial origin

University of Southern Queensland astrophysics professor Jonti Horner said he was confident the boom was not caused by a meteor or something exploding in the atmosphere.

"People would have seen it," he said.

"For a fireball to be big enough to get deep enough into the atmosphere and then explode to give a shock wave [and] a sound like this, the sound would have been heard over a larger area, but people would have also seen that fireball in the sky."

The Bureau of Meteorology said there were no thunderstorms around Mildura on Tuesday afternoon and it could find no connection between the noise and weather.

Sonic-boom theory

Some Mildura residents theorised the sound could have been a sonic boom from military aircraft breaking the sound barrier.

In 2024, the Singapore Air Force was identified as the likely source of a loud noise heard across southern Perth.

However, the Department of Defence said there were no fly-overs or training near Mildura on Tuesday.