A strong 6.2-magnitude quake hit off Indonesia's North Maluku province on Friday, local meteorologists said.
The quake struck at a depth of 110 kilometres around 12:43 pm, northeast of the town of Ternate.
"It was felt in Halmahera island but there is no report of damage,"
meteorology and geophysics agency official Oktivar told AFP.
The US Geological Survey (USGS) measured it at 6.3.
"We don't expect any damage as its epicentre was very deep in the sea," he added.
Indonesia sits on the Pacific "Ring of Fire", where the meeting of continental plates causes high volcanic and seismic activity, and powerful earthquakes frequently strike the archipelago.