BANGKOK (AlertNet) - An underwater earthquake similar to the one that triggered the 2004 Indian Ocean tsunami will strike near the Indonesian island of Sumatra within 30 years, a leading geologist said in an interview.

The forecast by Kerry Sieh, director of the Singapore-based Earth Observatory, adds weight to earlier research which point to another devastating tsunami in the region and puts the spotlight on efforts to improve survival rates through early warning systems.

Sieh predicted an 8.8-magnitude quake will hit a 400 km (250 miles) section of the Sunda Megathrust, one of the world's most active fault lines, on the west coast of Sumatra near the cities of Padang and Bengkulu.

More than 1 million people live in the region, roughly more than twice as many than on the Indonesian island of Aceh at the time of the 2004 tsunami. The catastrophe was caused by a 9.1 magnitude earthquake that triggered a massive tsunami across the Indian Ocean, killing estimated 230,000 people and displacing another 2.1 million.

"It would be the second biggest earthquake in 40 years, second only to the Aceh earthquake," Sieh told AlertNet.

"Our hunch is that it will occur within the next 30 years."

Sieh and his team at the Earth Observatory Singapore, a research institute linked to Nanyang Technological University, made the prediction by studying corals, which record sea-level changes in their growth patterns over hundreds of years, and data from global positioning systems.

"We know from looking at the past 700 years recorded in the corals that this section breaks in a series of large earthquakes about every 200 years," he said.

Once this period of activity starts it lasts a few decades. Two earthquakes of magnitudes 8.4 and 7.8 which hit southern Sumatra in September 2007 were the start of the seismic activity, but the big one is yet to come, Sieh said.

The section of the Sunda megathrust between Sumatra and Myanmar has generated more earthquake activity than any other place since 2000, he explained.

Indonesia has been putting early warning systems in place but Sieh said it would take about 15 minutes to sound the alarm while the ensuing tsunami would reach local shores in 30 minutes.

"The easiest thing to do after the tsunami in 2004 was to put in an early warning system. It was sexy, it was high-tech and appealed to politicians and citizens," Sieh said. "But it doesn't address the problems of local inhabitants when the earthquake happens very close to them."

Advocates of early warning systems say it will save thousands of lives but Sieh said it would be better to put more energy into persuading people who live in vulnerable areas to move.

"If we don't become more effective in mitigating these hazards, large parts of some coastal cities prone to rare tsunamis will be taken out this century, " Sieh said.

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