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Plate tectonic setting of Sunda megathrust
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The Sunda megathrust is a fault that
extends approximately 5,500 km (3300 mi) from Burma in the north, running along the
southwestern side of Sumatra, to the south of Java and Bali
before terminating near Australia.[1] It
is a megathrust, located at a convergent
plate boundary where it forms the interface between the
overriding Eurasian plate and the subducting Indo-Australian plate. It is one of the
most seismogenic structures on Earth, being responsible for many
great and giant earthquakes, including the 2004 Indian Ocean
earthquake and tsunami
that killed over 230,000 people. The Sunda megathrust can be
divided into the Andaman Megathrust, Sumatra(n)
Megathrust and Java(n) Megathrust. The Bali-Sumbawa segment is much less active and
therefore does not have the "megathrust" term associated with
it.
Tectonic
setting
The subducting plate consists of two protoplates, the Indian and Australian plates. Similarly the overriding
plate consists of two microplates, the Sunda and Burma plates. The relative motion of the
subducting and overriding plates varies slightly along strike due
to these complexities but is always strongly oblique. The
strike-slip component of the oblique convergence is accommodated by
displacement on the Great Sumatran fault, while the
dip-slip component is taken up by the Sunda megathrust.
Megathrust
geometry
The Sunda megathrust is curviplanar, forming an arc in map view
and, at least in Sumatra, increasing in dip from 5°-7° near the
trench, then increasing gradually from 15°-20° beneath the Mentawai
Islands to about 30° below the coastline of Sumatra.[2]
Earthquakes
Rupture areas for the 1861, 1833 and 2004 earthquakes and area of
main shock and aftershocks for the 2005 event, showing similarity
to 1861 quake
At this plate boundary, earthquakes occur along the Sunda
megathrust and within both the subducting and overriding plates.
The largest earthquakes are generated when the megathrust itself
ruptures. Studies of both recent and historical earthquakes show that
the megathrust is segmented.[1]
The largest earthquakes occur on separate 'patches' along the
megathrust surface (1797, 1833, 1861, 2004, 2005 & 2007), with smaller events occurring at the
boundaries between these patches (1935, 2000 & 2002).[1]
The rupture area of the 1861 event appears to be very similar to
that for the 2005 event, suggesting that it can be regarded as a
repeat event. The 2007 event is interpreted to be a partial failure
of the rupture area of the 1833 event.[1]
The 2004 earthquake ruptured an enormous segment of the
megathrust surface. Research into evidence for previous events of
this size suggests that they are rare, with two candidate earlier
events occurring soon after AD 1290-1400 and AD 780-990.[3]
The Java-Bali segment of the megathrust does not appear to be
associated with great earthquakes, possibly due to mainly aseismic
slip.[4]
List of Sunda megathrust
earthquakes
References
- ^ a
b
c
d
Sieh, K.. "The Sunda megathrust: past,
present and future". http://www.gps.caltech.edu/~sieh/pubs_docs/submitted/Snu.pdf. Retrieved
2009-11-04.
- ^ Chlieh, M.; Avouac J.P., Sieh K.,
Natawidjaja D.H. & Galetzka J. (2008). "Heterogeneous coupling of
the Sumatran megathrust constrained". Journal of
Geophysical Research 113 (B05305). http://www.tectonics.caltech.edu/publications/pdf/chliehJGR2008.pdf. Retrieved
2009-11-05.
- ^ Monecke, K.; Finger W., Klarer D., Kongko
W., McAdoo B.G., Moore A.L. & Sudrajat S.U. (2008). "A 1,000-year sediment record
of tsunami recurrence in northern Sumatra". Nature
455: 1232–1234. http://www.nature.com/nature/journal/v455/n7217/full/nature07374.html. Retrieved
2009-11-05.
- ^ Newcomb, K.R.; McCann W.R. (1987). "Seismic history and
seismotectonics of the Sunda Arc". Journal of Geophysical
Research 92 (B1): 421–439. ftp://ftp.gps.caltech.edu/pub/avouac/Ge277-2007-fall/Newcomb_JGR1987.pdf. Retrieved
2009-11-06.
- ^ a
b
Destructive historical
tsunamis at the western coast of Sumatra, Tsunami Laboratory,
Institute of Computational Mathematics and Mathematical Geophysics
Siberian Division Russian Academy of Sciences.
- ^
Sieh, K. 2006. Philosophical
Transactions of the Royal Society A, 364 no. 1845
1947-1963.
- ^ a
b
George Pararas-Carayannis,
The great earthquake and tsunami of 1833 off the coast of
Central Sumatra in Indonesia
- ^
Zachariasen, J., Sieh, K.,
Taylor, F.W., Edwards, R.L. & Hantoro, W.S. 1999. Submergence
and uplift associated with the giant 1833 Sumatran subduction
earthquake: Evidence from coral microatolls, Journal of Geophysical
Research, Vol. 104, No. B1, Pages 895–919.
- ^
Agarwal, P. & Shrikhande,
M. 2006. Earthquake Resistant Design of Structures. Prentice-Hall
of India Pvt.Ltd., 600pp.
- ^
Research Group on The December
26, 2004 Earthquake Tsunami Disaster of Indian Ocean
- ^ a
b
c
IISEENET (Information Network of
Earthquake disaster Prevention Technologies). "Search Parameters". http://iisee.kenken.go.jp/utsu/utsuweq_bak_eng.html. Retrieved
2009-11-04.
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