9/6/2007
BANGKOK : More than 1 million people in South Asia's Bay of Bengal could be swept to their deaths by a tsunami if a giant earthquake were to hit off the coast of Myanmar, according to a study published Thursday.
But the study's author, Phil Cummins, said he does not have enough data to say whether such a cataclysmic event - a quake projected to be from 8.5 magnitude to 9.0 magnitude - is likely to hit parts of Myanmar and Bangladesh in the next few decades or in several hundred years.
"I don't want to cause a panic. There is no reason anything like this would happen soon," said Cummins, of Geoscience Australia, the federal agency that carries out geoscientific research.
The threat of tsunamis has taken on added urgency in recent years after a 9.3-magnitude earthquake off Indonesia's Sumatra island in December 2004 triggered a tsunami that killed more than 230,000 people and left a half million homeless in a dozen countries.Myanmar and Bangladesh suffered relatively minor damage from the tsunami, with 61 people and two people killed, respectively.
Previous research had shown the potential for large quakes in the Bay of Bengal area but Cummins said his study, which appears in Thursday's issue of the journal Nature, is the first to suggest a big quake could spawn a tsunami "that could have pronounced impact on the Chittagong coast and the Ganges-Bhramaputra delta at the northern tip of" the bay.
The numbers of people at risk from a tsunami, Cummins wrote, may be "over a million," given that the region is home to Bangladesh's second largest city of Chittagong and there are tens of millions of people living just above sea level in the region.
Cummins has not presented his findings to the governments of Myanmar and Bangladesh. Officials from Myanmar and Bangladesh could not immediately be reached for comment.
The area Cummins studied is a section of the Sunda Megathrust known as the Arakan Subduction Zone where the Indian and Southeast Asia plates meet. The Sunda Megathrust stretches all the way from Western Australia to the Himalayas, and ruptures along that faultline were blamed for the Sumatra earthquake in 2004.
Examining historical records, Cummins found evidence that an earthquake estimated at magnitude 8.5 to 9.0 struck off the western Myanmar coast in April 1762 - the most recent large quake found in the records.
He said it probably produced a tsunami, citing eyewitness accounts of waves washing over nearby Cheduba Island, submerged coasts near Chittagong and causing river levels as far inland as the Bangladeshi capital Dhaka - about 100 kilometers.
He said future quakes and tsunamis were likely, given the historical accounts and more recent surveys of the area, which determined a magnitude 8.5 quake would hit the area every 100 years and a 9.0 every 500 years.
"I would hope this spurs further work in confirming these past events," he said. "It should be possible to answer how big was this event, how often do these events occur and what kind of tsunamis are generated through further geological investigation."
He said it was difficult for local authorities to take action to prevent the disaster, since it was not an immediate threat and any tsunami would probably inundate threatened regions from within 10 minutes to two hours.
The reaction to Cummins' findings has been mixed, with some tsunami experts saying they shed important light on a section of Sunda Megathrust that has received little attention in the past.
"The main value of the paper is in advertising the danger of the section of the megathrust that no one has worried about," said California Institute of Technology's Kerry Sieh, who has used coralrecords and GPS networks to predict that a big quake and tsunami are likely to hit parts of Sumatra Island in the coming decades.
"The effects on the west coast of Myanmar and more importantly Bangladesh would be awful," he said.
But Costas Synolakis, director of the Tsunami Research Center at the University of Southern California, insisted he and others presented findings at earlier seminars showing there was a threat of a quake-generated tsunami in the Bay of Bengal but that the worst impact would be in Sri Lanka.
"There is nothing new here," Synolakis said in an e-mail interview.
Synolakis also said the scenario presented by Cummins "could lead to a massive panic south of Chennai (India) and possibly a sense of reassurance in Sri Lanka," where he said the threat of another tsunami was worse.
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