More strong earthquakes have struck off Western Australia's north coast after Sunday's magnitude 6.6, which was felt from Darwin to Perth.
Multiple undersea quakes were recorded off the coast between Port Hedland and Broome on Monday morning.
The strongest was a magnitude of 5.1 and 5.5.
A magnitude 6.6 quake struck in the same area on Sunday afternoon and was felt from Perth to Darwin.
It was the equal-biggest earthquake ever recorded in Australia, matching a quake in Tennant Creek in the Northern Territory in 1988.
Geoscience Australia seismologist Spiro Spiliopoulos said more than 30 quakes had been recorded in the area in less than 24 hours and more were expected.
"The Tennant Creek aftershocks went for a very long time - we got small earthquakes there years after the main shock," he told AAP.
"It's not unusual. They can go on for days, weeks."
The quakes could be related to mapped fault lines in the area, Mr Spiliopoulos said.
