A moderate quake with a magnitude of 5.0 jolted islands in Indonesia's Ceram Sea early on Sunday, meteorologists said, but there were no immediate reports of casualties or damage.
The quake occurred at 1.11 IST on Sunday with its epicentre 312 kilometres south of Sorong in the eastern province of Irian Jaya at a depth of 14 kilometres, the US Geological Survey said.
The reading was based on the open-ended Moment Magnitude scale, now used by US seismologists, which measures the area of the fault that ruptured and the total energy released.
A measurement of five indicates a moderate earthquake.
Indonesia sits on the Pacific "Ring of Fire", where the meeting of continental plates causes high volcanic and seismic activity.
A strong earthquake struck the city of Yogyakarta and its surrounds on the main Indonesian island of Java on May 27, killing some 5,800 people.