Hong Kong: A powerful 7.1-magnitude earthquake struck in the southern Indian Ocean on Saturday (Dec 5), but there was a low likelihood of casualties and damage, US seismologists said.

The shallow tremor struck at 6:24am (2224 GMT Friday), some 1,020km (634 miles) east-northeast of 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 seafloor of the southern Indian Ocean.