A 7.1 earthquake has struck 138km kilometres northwest of Kota Ternate in Indonesia's Molucca islands, the US Geological Survey said.
The quake struck at 11.17pm local time and was measured at 45 km deep, USGS said. Earlier, the agency put the magnitude at 7.4.
It was followed by three aftershocks, from 4.8 to 5.8 magnitude, in the same area.
Residents fled their homes to higher ground but there were no immediate reports of damage in Ternate, the largest city in the area, according to Metro TV news broadcaster.
The quake was also felt strongly on the island of Sulawesi, to the west of the epicentre.
Indah Lengkong, a resident of port city of Bitung in North Sulawesi, said by text message: "The house was visibly shaking."
People in her neighbourhood had initially panicked, she said, adding: "The quake was very strong and lasted for a while. We can still feel tremors but weaker."
A resident of in Tondano in North Sulawesi posted to Twitter that she also felt the quake strongly.
Indonesia's Meteorology and Geophysics Agency withdrew a tsunami alert it had issued after the earthquake, and the Pacific Tsunami Warning Center said there was no threat in the Pacific.