|Residents gather outside their homes in Ternate after a strong 6.9-magnitude earthquake struck off Indonesia. (STR/AFP) |
The Southeast Asian nation is one of the most disaster-hit on Earth due to its position straddling the so-called Pacific Ring of Fire, where tectonic plates collide.
Earthquakes and tsunamis have claimed thousands of lives in recent years.
Sunday's quake struck at a depth of 24km in the Molucca Sea, 185km southeast of Manado, between Sulawesi and Malkuku islands, according to the USGS.
Indonesia's geophysics agency issued a tsunami warning for coastal communities nearby, where residents were advised to stay away from the coast.
The warning was later lifted by the agency and there were no immediate reports of damage or casualties.
"The quake was felt quite strongly and with an intensity that lasted quite long," said Yusuf Latif, a spokesman for the search and rescue agency.
"There were no reports of damage or casualties in Ternate," he added, referring to the city closest to the epicentre.
Residents of Ternate in the Maluku island chain described panic as the quake hit.
"I was getting ready to sleep when the window started rattling," Budi Nurgianto told AFP.
"It was very strong - I ran from my house and all my neighbours fled too."
Video footage from Ternate showed scared residents - some clutching children - fleeing from the coast on motorbikes.
Hasyim Yusuf, the head of the Ternate disaster mitigation agency, said there were no reports of fatalities, but some people were "traumatised" by the tremor.
"In Ternate, people were panicking and some evacuated to higher ground," he told Metro TV.
An official from Indonesia's geophysics agency, Ot Oral Sem Wilar, said he felt the tremor strongly from where he was holidaying in North Sulawesi.
"My friends in Manado said people who live along the coastal area are evacuating."
The USGS warned that considerable damage was possible in poorly built or badly designed structures.
In a Facebook post, the Singapore embassy in Jakarta warned Singaporeans about the earthquake and tsunami alert.
"Singaporeans in the proximity of the affected area are advised to monitor the local news closely and take the necessary precautions," it said.
Singaporeans can contact the Singapore embassy office in Jakarta or the Ministry Foreign Affairs duty office for consular assistance.
A consular notice by the Malaysian embassy in Jakarta has been issued to warn its citizens about the earthquake and tsunami alert.
"Malaysians in the surrounding areas (of North Sulawesi) are advised to take precautionary steps and follow the latest directions from the local authorities," it said.
Last year, a 7.5-magnitude quake and a subsequent tsunami in Palu on Sulawesi island killed more than 2,200 with a thousand more declared missing.
It has been hit by a string of deadly quakes including a devastating 2004 tremor measuring 9.1 magnitude that struck off the coast of Sumatra and triggered a tsunami that killed 220,000 throughout the region, including 168,000 in Indonesia.
The Boxing Day disaster was the world's third-biggest quake since 1900, and lifted the ocean floor in some places by 15 metres.
Indonesia's Aceh province was the hardest hit area, but the tsunami affected coastal areas as far away as Africa.