An earthquake of magnitude 6.3 struck off Ambon in Indonesia's Molucca islands, the United States Geological Survey said.
There were no immediate reports of damage or casualties from the quake.
It struck at a depth of 110 km (68 miles) about 38 km (24 miles) west of Ambon.
Ambon has a population of more than 350,000.
The affected area sits on the Australia-Pacific plate boundary, which is thousands of kilometres long.
Large earthquakes are common in the region, the USGS said.
Previous large quakes in the plate boundary include 1 April 2007, when a tsunami killed 40 people.
Earthquakes in the area have the potential to cause large-scale damage and loss of life.
This is partly due to secondary effects such as landslides, and the fact that most people live in structures of concrete floors and unreinforced brick that are vulnerable to earthquake shaking,
Ambon is mostly surrounded by much smaller towns and villages of less than 1,000 people.
The news comes a week after New Zealand was hit by a 5.5 magnitude quake and causing landslides, but no casualties were reported.
