Minor tectonic plate in Southeast Asia
The
Burma Plate
is a minor
tectonic plate
or microplate located in
Southeast Asia
, sometimes considered a part of the larger
Eurasian Plate
. The
Andaman Islands
,
Nicobar Islands
, and northwestern
Sumatra
are located on the plate. This
island arc
separates the
Andaman Sea
from the main
Indian Ocean
to the west.
To its east lies the
Sunda Plate
, from which it is separated along a
transform boundary
, running in a rough north-south line through the Andaman Sea. This boundary between the Burma and Sunda plates is a marginal
seafloor spreading centre
, which has led to the opening up of the Andaman Sea (from a southerly direction) by "pushing out" the Andaman-Nicobar-Sumatra
island arc
from mainland Asia, a process which began in earnest approximately 4 million years ago.
To the west is the much larger
India Plate
, which is subducting beneath the western facet of the Burma Plate. This extensive
subduction zone
has formed the
Sunda Trench
.
Tectonic history
[
edit
]
In models of the reconstructed tectonic history of the area, the generally northwards movement of the
Indo-Australian Plate
resulted in its substantive collision with the
Eurasian
continent
, which began during the
Eocene
epoch
, approximately 50?55 million years ago (
Ma
). This collision with Asia began the
orogenic uplift
which has formed the
Himalaya
mountains, as well as the fracturing of the Indo-Australian plate into the modern Indian Plate,
Australian Plate
, and possibly
Capricorn Plate
.
[2]
As the India Plate
drifted
northwards at a relatively rapid rate of an average 16 cm/yr, it also rotated in a
counterclockwise
direction. As a result of this movement and rotation, the
convergence
along the plate's eastern boundary (the Burma-Andaman-Malay region) with Eurasia was at an
oblique
angle.
The transform forces along this subduction front started the clockwise bending of the Sunda arc; in the late
Oligocene
(ca. 32 Ma) further faulting developed and the Burma and Sunda microplates began to "break off" from the larger Eurasian Plate.
After a further series of transform faulting, and the continuing subduction of the India Plate beneath the Burma Plate,
backarc spreading
saw the formation of the
marginal basin
and seafloor spreading centre which would become the Andaman Sea, a process well-underway by the mid-
Pliocene
(3?4 Ma).
Recent tectonic activity
[
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]
On December 26, 2004, a large portion of the boundary between the Burma Plate and the
Indian Plate
slipped, causing the
2004 Indian Ocean earthquake and tsunami
.
[3]
This
megathrust earthquake
had an estimated
moment magnitude
of 9.1?9.3
.
[4]
Over 1,600 kilometres (990 mi) of the boundary underwent
thrust faulting
and shifted up to 5 metres (16 ft) vertically and 11 metres (36 ft) horizontally.
[4]
This rapid rise in the sea floor over such a short time (seven minutes
[4]
) generated a massive
tsunami
that killed approximately 229,800 people along the coast of the Indian Ocean.
References
[
edit
]
Further reading
[
edit
]
- Curray, JR.
"2002 Chapman Conference on Continent ? Ocean Interactions within the East Asian Marginal Seas"
(PDF)
.
Tectonics and History of the Andaman Sea Region (abstract)
. Archived from
the original
(PDF)
on March 23, 2005
. Retrieved
September 8,
2005
.
pdf
- Paul, J., Burgmann, R., Gaur, V. K., Bilham, R.,
Larson, K. M.
, Ananda, M. B., Jade, S., Mukal, M., Anupama, T. S.. Satyal, G., Kumar, D. 2001 The motion and active deformation of India. Geophys. Res. Lett. Vol. 28, No. 04, 647?651 2001.
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Large
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Small
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Philippines
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Indonesia
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New Guinea
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Faults
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Trenches
and
troughs
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Sulawesi and Moluccas
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Timor
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New Guinea
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Subsea plateaus
and basins
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