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A US Navy F-18 Hornet fighter plane breaks the sound barrier.
Reuters A US Navy F-18 Hornet fighter plane breaks the sound barrier.

UPDATE: Vibrations which rattled windows across Perth this afternoon were caused by a Defence Force pilot in an F-18 fighter jet breaking the sound barrier.

A Defence Force spokesman told thewest.com.au that a “cloud inversion layer” and onshore winds had caused sonic booms from the exercise, which was conducted 50 nautical miles (92.6km) off the coast, to be felt across the suburbs.

The exercise was carried out shortly after 12.30pm and it is understood the pilot made two runs.

The spokesman said it was very unusual for the sound to carry so far and the last time he had experienced a similar occurrence was six years ago.

The exercise was a part of a five week operation, called Triton Storm 2, which has seen three Australian and New Zealand Anzac-class frigates and jet planes and helicopters from both nations battle for supremacy of sea and sky in a series of war games.

The vibrations caused widespread confusion today, with many residents assuming that an earthquake recorded north-east of Perth was the cause of rattling windows and doors.

But Geoscience Australia squashed the rumours, saying tremors in the metro area were probably not caused by an earthquake.

Geoscience Australia geoscientist Emma Mathews said while a magnitude 2 earthquake was recorded at Bonnie Rock, 250km north-east of Perth, it was unlikely to have caused the reports of shaking windows and rattling doors from areas as far away as Rockingham and Golden Bay.

Did you feel the sonic boom? Let us know about it

“It’s not consistent with the seismic event we’ve recorded,” she said. “The amount of reports in Perth don’t mirror the magnitude.”

Ms Matthews said it was possible there had been a series of coincidences or the shaking windows were caused by irregular air traffic.

Readers from Gidgegannup to Rockingham have reported feeling the “quake”, which was recorded at 12.41pm. Others south of Perth reported hearing a boom-like noise.

“I was sitting at home around 1pm and my house started slightly shaking, enough to notice it and I started thinking it felt like a mini earthquake,” one reader in Gidgegannup said.

Another reader in Warnbro said her front doors shook “violently” and the bed moved.

A reader from Rockingham said the back door and windows started rattling at about 2pm.

“It lasted about 10 seconds, I had no idea what was going on!”

Another reader from Greenfields said there was two "tremor-like episodes" at 12.45pm and 1pm.

"Having lived through the 1968 Meckering Quake and the Perth Quake in the late 1970's I wondered if it was indeed tremors," the reader said.

"In both instances I heard a loud bang as if something heavy had fallen followed by the windows and floors shaking for a few seconds."

One woman said three loud booms at about 12.30pm to 1pm shook the glass doors and windows of her house on Rottnest Island.

“It frightened me so much I almost choked on my lunch,” she said.