Seismologists are already sure that Monday's magnitude 8.7 quake off Indonesia's Sumatra island was a direct result of raised stress levels in the Earth's crust caused by the 26 December tremor.

And they say there is now a heightened risk of further large quakes - not just aftershocks - in the area, although predicting them accurately remains impossible.

"Unfortunately that is a real possibility - the world works that way," Professor John McCloskey, head of environmental sciences at the University of Ulster, in Northern Ireland, said.

"Earthquakes tend to trigger each other so one earthquake is followed by others."

Chilling prediction

In a report published in mid-March that proved chillingly accurate, McCloskey's research team said the magnitude 9 December quake, which left nearly 300,000 people dead or missing around the Indian Ocean, had significantly raised stress levels in the Sunda trench near the west coast of Sumatra island.

"Earthquakes tend to trigger each other so one earthquake is followed by others"

Professor John McCloskey
Head of environmental sciences, University of Ulster

Less than two weeks after the report, the world's seventh most powerful quake in the past 100 years struck along the trench, killing as many as 2000 people on tiny Nias island and surrounding areas.

It did not trigger a tsunami, unlike the December quake and previous earthquakes on the Sunda trench in 1833 and 1861.

In the March report, McCloskey's team also said the 26 December quake had raised stress levels even more substantially along the Sumatra fault near the city of Banda Aceh, which bore the brunt of the Boxing Day tsunami.

Domino effect 

"I'm not saying the domino effect will happen in that way but there are good physical reasons why that domino type of effect can happen," said McCloskey.

"And it would not be wise to assume: That's the second big earthquake, let's forget about it now. This is an active area ... it's been like this for probably millions of years." 

Seismologists are now looking at the experience of Turkey for clues to what might happen in Asia.

Turkey, situated where the Arabian and African plates clash with the Eurasian plate, was hit by 11 major earthquakes last century, the latest a 7.4 magnitude tremor in Izmit in 1999 that killed more than 30,000.

The 26 December quake triggered
a tsunami, killing 300,000 people

"It's a risk. It does happen ... it's happened in Turkey and Japan, but it doesn't always happen so it's difficult to say," said Phil Cummins, a seismologist at GeoScience Australia.

"Certainly there's increased risk and we need to exercise caution in the future".

Each point on the scale measuring earthquakes represents a 30-fold increase in energy, but a quake's destructiveness also depends on the depth of its epicentre, the population concentration and people's preparedness.

Public awareness

McCloskey said the increased risk of quakes in Southeast Asia raised the importance of educating people about proper building techniques and safety drills.

"It's a real live issue when people are rebuilding. If you allow cowboys to build, people will die as a result," said McCloskey.

But deep poverty and lack of education in areas such as northern Indonesia mean earthquakes will inevitably prove more destructive than in richer countries.

Triman Zega, an 18-year-old gardener on Nias island, said he has never had any training on how to respond to an earthquake.

"The best thing is to follow my instinct - run," he said.