Study finds tsunami risk in Bay of Bengal
Michael Casey
THAILAND: At least a million people in South Asia's Bay of Bengal
could be swept to their deaths by a tsunami if a giant earthquake hits
off the coast of Burma, according to a study published on Thursday.
But the study's author, Phil Cummins, said he does not have enough
data to say whether such a cataclysmic event would hit parts of Burma
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 threat of tsunamis has taken on
added urgency in recent years after a massive 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.
Cummins' study, which appears in Thursday's issue of the journal
Nature, is the first time anyone has suggested that an earthquake off
the coast of Burma could spawn a tsunami "that could have pronounced
impact on the Chittagong coast and the Ganges-Brahmaputra delta at the
northern tip of the Bay of Bengal," it said.
The numbers of people at risk from a tsunami, he 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 living just above sea
level.Cummins has not presented his findings to the governments of Burma
and Bangladesh. Officials from Burma and Bangladesh could not
immediately be reached for comment.
The area Cummins studied is a section of the Sunda Megathrust that
stretches all the way from Western Australia to the Himalayas. A rupture
of the fault was 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
Burma coast in April 1762. He said it probably produced a tsunami,
citing eyewitness accounts of waves washing over nearby Cheduba Island,
submerged coasts near Chittagong and rising river levels as far inland
as Dhaka. 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." 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 coral
records and GPS networks to predict that a big quake and tsunami are
likely to hit parts of Sumatra Island in the coming decades. "His point
is well taken. This part of the Megathrust has produced a larger
earthquake in the past and so it could do so in the future too," Sieh
said.
"The effects on the west coast of Burma, and more importantly
Bangladesh, would be awful." But Costas Synolakis, director of the
Tsunami Research Centre at the University of Southern California, said
the possibly of a tsunami in the area was previously known and
questioned whether the fault would rupture to the extent estimated by
Cummins.
Synolakis also said in an e-mail interview that the scenario
presented by Cummins "could lead to a massive panic south of Chennai and
possibly a sense of reassurance in Sri Lanka", where he said the threat
of another tsunami was worse.
(AP)
Asian Age, Bangkok, Sept. 5
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