A strong earthquake measuring 6.1 on the Richter scale rocked Indonesia's remote northernmost Talaud Islands early Saturday but there were no reports of casualties, meteorologists said.
The under-sea quake struck at 5.14 am local time (2114 GMT) with its epicentre 42 kilometres (27 miles) southwest of Kepulauan Talaud district, said Lukito of the Meteorology and Geophysics Agency in Jakarta.
Its depth was 33 kilometres below the surface, he said.
"According to local authorities there were no reports of casualties or damage," he said.
Indonesia sits on the Pacific "Ring of Fire", where the meeting of continental plates causes high volcanic and seismic activity.
A massive earthquake off Aceh on December 26, 2004 triggered a tsunami that devastated coastlines around the Indian Ocean and left more than 220,000 people dead.