Scientists detect signs but cannot predict when or where it will strike
Tania Tan, Straits Times 5 Dec 08;
AS INDONESIA prepares to mark the fourth anniversary of the Boxing Day tsunami that killed more than 200,000 people, new scientific findings are painting a grim picture.
An earthquake potentially larger than the one that triggered the 2004 tsunami is threatening off Sumatra, researchers from the Nanyang Technological University (NTU) said yesterday.
'What we are now trying to understand is how close it is to happening,' said Professor Kerry Sieh, director of the university's Earth Observatory of Singapore.
Sumatra lies above one of the most active earthquake sites in the world known as the Ring of Fire.
Using satellite and field data collected after an earthquake in September last year near the island's coast, researchers found something ominous.
While the tremor released some of the tremendous pressure created by the movement of the Earth's tectonic plates, a large amount of tension remains.
Researchers say that is a recipe for a major quake that could be larger than the 9.2- magnitude tremor in the Indian Ocean that unleashed the 2004 tsunami.
But the scientists are not sure when or where the earthquake will strike, making it impossible to predict whether the fallout will be as devastating as in 2004.
About 20 people died in an 8-magnitude quake last year which uprooted nearby coral reefs, lifting them up to one metre above the ocean's surface.
The tectonic plates off Sumatra last experienced such a large shift in 1797 and 1833, said Prof Sieh.
Singapore is too far from the Ring of Fire to suffer severe effects from earthquakes in that region, but tremors were felt here during last year's quake.
Eventually, scientists from NTU's Earth Observatory of Singapore hope to develop a system to forecast earthquakes 10 to 20 years before they happen, said Prof Sieh.
'That's the time scale that governments and engineers need to build better infrastructure, and the time it takes to educate the next generation about how to avoid being caught in a disaster.'
Getting there, however, will be difficult.
'The science of earthquake prediction is still at a stage where it's very imprecise,' said Associate Professor Lee Fook Hou, head of the Centre for Hazards Research at the National University of Singapore.
This is because large earthquakes - which throw up the most scientific data - happen once every hundred or thousand years, explained Prof Lee.
'We just don't have enough information right now.'
Learning about past quakes - from corals
Straits Times 5 Dec 08;
UNCOVERING the history of earthquakes has been an uphill task for researchers, as data from past tremors is hard to come by.
Scientists, however, have discovered that coral reefs can tell the story of earthquakes that occurred more than 200 years ago.
The growth patterns of corals reflect the stability of the land mass, or tectonic plate, that they sit on.
The earth's crust is made of several plates that are in constant motion.
Bowl-shaped corals suggest plates that are constantly shifting, while flat-top corals point to stable land, explained Earth Observatory of Singapore director Kerry Sieh.
Researchers from several universities, including the California Institute of Technology and the Indonesian Institute of Science, descended last year upon the Mentawai Islands near Sumatra.
The Mentawai coral reefs, which are several hundred years old, are bowl-shaped - consistent with the constant seismic activity in the area.
The history of earthquakes in the region gives scientists precious data to develop future prediction models.
Understanding when earthquakes occur could, in turn, help governments and policymakers to develop better infrastructure and save lives.
TANIA TAN
