A series of earthquakes that rocked Indonesia last week has once again highlighted the danger faced by people living in a country that sits on the Pacific Ring-of-Fire.

Sunday saw earthquakes shake Manokwari in West Papua and Gorontalo in Sulawesi, measuring 6.1- and 5.3-magnitude respectively on the Richter scale.

The incidents happened only days after a 7.6-magnitude quake struck West Sumatra, on Wednesday, and another one hit Jambi on Thursday.

Abdul Haris, a geophysicist from the University of Indonesia, said the country is likely to experience stronger quakes in the next few years.

"It's a cycle, the earth had suppressed its energy and it has been releasing the big ones since 2003 and will keep doing it until at least 2014," he told The Jakarta Post on Sunday.

He urged the government to map the areas in the country that are yet likely to experience powerful quakes to prepare better mitigation measures.

"There is a small possibility that the same areas will be affected."

Abdul said if the government had suitable mitigation measures, the number of victims would have not been so large.

The death toll in Padang and its surrounding areas in West Sumatra has reached more than 700.

Officials feared the number could reach thousands.

The quake was also felt in other provinces in Sumatra such as Jambi, North Sumatra and Riau as well as in Malaysia and Singapore.

Geologist Danny Hilman Natawidjaja from the Indonesian Institute of Sciences said there was a possibility that West Sumatra would experience another energy explosion.

"If we calculate the bicentennial cycle of earthquakes occurring in Sumatra, we can see that there is a potential of energy release in the areas in the Mentawai islands regency," he told the Post.

The regency was hit by a powerful 7.9-magnitude earthquake in Sept. 2007, but Danny said the quake had only released around one-third of the total potential energy in the fault line.

"The remaining two-thirds of energy, if released all at once, could result in an 8.8- to 8.9-magnitude earthquake."

However, he said, no research could tell exactly when the violent quake would hit.

"Although the Mentawai fault is at the end of its earthquake cycle, the energy explosion might not happen for the next 10 to 20 years, although it could happen tomorrow or next week. There's no way to tell," said Danny, who has been studying the Mentawai fault for 20 years.

He also said that he feared that the quake that hit West Sumatra provincial capital Padang might have had an impact on the Mentawai fault, causing it to speed up the process of the energy release.

"The Padang quake struck the side of the Mentawai fault," he said, adding that the same earthquake might have triggered the one that hit Jambi in West Sumatra.

Abdul said the quakes that swayed Manokwari and Gorontalo might also have been triggered by the violent quake that struck Padang. (adh)