New York, Sept 08: The densely populated Bay of
Bengal looks to be at risk from very large tsunami-producing
earthquakes, suggests a paper published in Nature magazine
this week.
Contrary to some previous studies, the plate boundary in
this region is probably at sea, hidden below the thick layer
of sediments in the Bengal fan, says the author, explaining
that this means that a subduction-zone earthquake would be
likely to generate a tsunami.
Evidence of a large earthquake in Myanmar's Arakan in
1762 also indicates an off-shore origin, the study says.
Phil Cummins, a seismologist at the National Geoscience
Australia Agency in Canberra, is also quick to caution that
his ideas need confirmation before "policymakers start doing
anything".
The northern Bay of Bengal was formerly thought to be an
unlikely place for large earthquakes that result when tectonic
plates that are pushing against one another suddenly wrench,
with one plate slipping below the other, The Nature said.
These 'megathrust' earthquakes can cause tsunamis, as
water is suddenly displaced up and down by the thrusting rock.
The plate boundary further south off the coast of Sumatra
causes such quakes -one of which created the devastating 2004
wave.
Previous research had hinted that further north, the
plate boundary comes ashore in Myanmar rather than continuing
up into the northern end of the Bay of Bengal, that the Indian
Ocean plate is not subducting there and that the land beneath
Myanmar is instead moving north with the Indian continental
plate.
But the seismological and geological evidence for this is
complex and open to interpretation.
Bureau Report
First Published: Saturday, September 08, 2007, 00:00