The shallow tremor struck at 6:24am (5:24am Thailand time), around 3,100 kilometres southwest of the Australian city of Perth and 1,000 km from the uninhabited Heard Island and McDonald Islands, the US Geological Survey said.
The epicentre was at the Southeast Indian ridge, a tectonic plate boundary located along the sea floor of the southern Indian Ocean.
The Joint Australian Tsunami Warning Centre said there was currently no threat of a tsunami to Australia.


