The United States Geological Survey on Thursday reported aftershocks of magnitude as high as 5, and Indonesia's meteorology agency BMKG reported tsunami waves in West Halmahera at 30cm high and Bitung at 20cm.
Indonesian broadcaster Metro TV reported one person had died from falling rubble in the Manado area and video showed damaged buildings.
A Manado resident told Reuters that people ran out of their houses in panic. There was no visible damage in her neighbourhood, but items fell off shelves and power had been cut.
Indonesia straddles the Pacific Ring of Fire, a highly seismically active zone, where different plates on the earth's crust meet and create a large number of earthquakes and volcanoes.
Regional governments in some cities, such as on Ternate and Tidore, the historic Spice Islands, were urged to prepare citizens for evacuation.
Hazardous tsunamis were possible along the coasts of Indonesia, the Philippines and Malaysia within 1000km of the epicentre, US tsunami warning authorities said.
The epicentre of the quake was about 580km south of the Philippine coast and 1000 km from Malaysia's Sabah.
The Philippines' seismology agency Phivolcs said there was "no destructive tsunami threat" to the country based on latest data.
Malaysia's meteorological department said in a Facebook post there was no tsunami threat to Malaysia at the moment and that it was monitoring developments
Waves of heights ranging from 30cm to one metre above the tide level could hit some coastal areas of Indonesia, the Pacific Tsunami Warning Center said.
It also warned of the risk of waves less than 30cm over tide levels for the coasts of Guam, Japan, Malaysia, Papua New Guinea, the Philippines and Taiwan.
Japan may see waves of up to 20cm, but no damage is expected, the Japan Meteorological Agency said, as it warned a tsunami could occur in the Pacific.
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