The tremor struck at a depth of 114 km, according to the to German Research Center for Geosciences.
The Indonesian geophysical institute BMKG put the quake's magnitude at 6.1.
There is no tsunami threat.
Indonesia is located in a seismically active zone known as the Ring of Fire and regularly suffers from powerful earthquakes.
Hundreds of thousands of people died in 2004 when a 9.2 magnitude earthquake hit Sumatra's Aceh region, triggering a tsunami that hit numerous countries bordering the Indian Ocean.