The underwater earthquake, which occurred at a depth of 30km (19 miles), occurred to the southeast of Sulawesi Island, 2,160 kilometers (1,350 miles) northeast of the capital, Jakarta. The quake occurred at 4.48 p.m. local time (9.48 a.m. GMT).
Immediately after the earthquake, a tsunami warning was issued.
Two earthquakes, a 7.7 tremor and a 6.7-magnitude tremor, were also registered near the western coast of Indonesia's island of Sumatra early Thursday, the country's Meteorology and Geophysics Agency said. The more powerful of these occurred about 30km (19 miles) under the sea, around 130km (80 miles) south-west of the city of Bengkulu. Tsunami warnings were also issued.
Indonesia has been hit by a series of earthquakes in the past few days in the south Sumatra region, leading to repeated tsunami warnings. However, to date, only a minor tsunami 1m (3ft) off the coast of Sumatra is reported to have hit the country, reports Indonesia's meteorology agency.
On December 26, 2004, an earthquake off the coast of Sumatra, measuring 9.0 on the Richter scale, generated a huge tsunami that killed more than 275,000 in a dozen nations, the majority in Indonesia's Aceh province.