Sunda megathrust

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September 2007 Sumatra earthquake
shown by star

The Sunda megathrust is a

2004 Indian Ocean earthquake and tsunami that killed over 227,000 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

Plate tectonic setting of Sunda megathrust

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

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

This table lists Sunda Megathrust quakes with magnitudes of 7 or greater, or any known to have caused deaths. Historic records before 2004 are incomplete.

Date/Time‡ Location Coordinates Fatalities Magnitude Comments Sources
1797-02-10 just north of
Mentawai islands
 1°00′S 99°00′E / 1.0°S 99.0°E / -1.0; 99.0 300 8.4 See 1797 Sumatra earthquake [5][6][7]
1833-11-25 50 km NE of
Mentawai islands
 2°30′S 100°30′E / 2.5°S 100.5°E / -2.5; 100.5 "numerous victims" 8.8–9.2 Mw See 1833 Sumatra earthquake [5][7][8]
1843-10-05 Nias 1°30′N 98°00′E / 1.5°N 98.0°E / 1.5; 98.0 "many killed" ≥7.8 Mw Caused a devastating tsunami. Maximum intensity XI (Extreme). See 1843 Nias earthquake [9]
1861-02-16 Nias 1°00′N 97°30′E / 1.0°N 97.5°E / 1.0; 97.5 905 8.5 Caused major tsunami. See 1861 Sumatra earthquake. [10][11]
1907-01-04 05:19 just west of Simeulue 2°30′N 95°30′E / 2.5°N 95.5°E / 2.5; 95.5 2,188 8.2–8.4 Tsunami earthquake that caused a tsunami that devastated Simeulue and Nias, see 1907 Sumatra earthquake [12]
1935-12-28 02:35 just west of the Batu Islands 0°00′N 98°12′E / 0.0°N 98.2°E / 0.0; 98.2 7.7 See 1935 Sumatra earthquake [13]
1984-11-17 06:49 Between Nias and the Batu Islands 0°12′N 98°02′E / 0.20°N 98.03°E / 0.20; 98.03 7.2 See 1984 Northern Sumatra earthquake [14]
2000-06-04 16:28 70 km NNW of Enggano Island 4°43′S 102°05′E / 4.72°S 102.09°E / -4.72; 102.09 46 7.9 See
2000 Sumatra earthquake
 [13]
2002-11-02 01:26 8 km north of Simeulue Regency 2°49′N 96°05′E / 2.82°N 96.09°E / 2.82; 96.09 3 7.3 See 2002 Sumatra earthquake [13]
2004-12-26 00:58 50 km north of Simeulue Regency 3°18′N 95°52′E / 3.30°N 95.87°E / 3.30; 95.87 227,898 9.3 Mw (USGS) See
2004 Indian Ocean earthquake
2005-03-28 16:09 Bangkaru, Banyak Islands 2°05′N 97°07′E / 2.08°N 97.11°E / 2.08; 97.11 1,303 8.6 Mw (HRV) See 2005 Nias–Simeulue earthquake
2007-09-12 11:10 125 km SW of Bengkulu 4°31′01″S 101°22′55″E / 4.517°S 101.382°E / -4.517; 101.382 25 8.4 Mw (HRV) See
September 2007 Sumatra earthquake
2007-09-12 23:49:04 UTC 205 km NW of Bengkulu 2°30′22″S 100°54′22″E / 2.506°S 100.906°E / -2.506; 100.906 - 7.9 Mw (USGS) See
September 2007 Sumatra earthquake
2007-09-13 03:35:26 UTC 165 km SSW of Padang 2°09′36″S 99°51′04″E / 2.160°S 99.851°E / -2.160; 99.851 - 7.0 Mw (USGS) See
September 2007 Sumatra earthquake
2008-02-20 08:36:35 UTC 310 km SSE of Banda Aceh 2°46′41″N 95°58′41″E / 2.778°N 95.978°E / 2.778; 95.978 3 7.4 Mw (USGS) See 2008 Simeulue earthquake [15]
2008-02-25 08:36:35 UTC 160 km SSW of Padang 2°21′07″S 100°01′05″E / 2.352°S 100.018°E / -2.352; 100.018 7.2 Mw (USGS) [16]
2009-09-30 10:16:10 45 km WNW of Padang 0°43′30″N 99°51′22″E / 0.725°N 99.856°E / 0.725; 99.856 6,234 7.6 Mw (USGS) See 2009 Sumatra earthquakes
2010-04-06 22:15:02 UTC 215 km SW of Medan 2°21′36″N 97°07′55″E / 2.360°N 97.132°E / 2.360; 97.132 62 injuries 7.8 Mw (USGS) See April 2010 Sumatra earthquake
2010-05-09 05:59:42 UTC 215 km SSE of Banda Aceh 3°44′49″N 96°00′47″E / 3.747°N 96.013°E / 3.747; 96.013 - 7.2 Mw (USGS) [17]
2010-10-25 14:42:22 UTC 240 km W of Bengkulu 3°27′50″S 100°05′02″E / 3.464°S 100.084°E / -3.464; 100.084 435 & 100
missing
 7.7 Mw (USGS) See 2010 Mentawai earthquake and tsunami [18]

References

  1. ^
    doi:10.1142/S179343110700002X
    .
  2. doi:10.1029/2007jb004981
    . Retrieved 2009-11-05.
  3. S2CID 4420620
    .
  4. doi:10.1029/JB092iB01p00421
    . Retrieved 2009-11-06.
  5. ^ a b Kalashnikova Tamara. "Destructive historical tsunamis at the western coast of Sumatra, Tsunami Laboratory, Institute of Computational Mathematics and Mathematical Geophysics Siberian Division Russian Academy of Sciences". Tsun.sscc.ru. Retrieved 2010-10-26.
  6. S2CID 8562675
    .
  7. ^ a b "George Pararas-Carayannis, The great earthquake and tsunami of 1833 off the coast of Central Sumatra in Indonesia". Drgeorgepc.com. Retrieved 2010-10-26.
  8. ^ "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" (PDF). Retrieved 2010-10-26.
  9. S2CID 59068187
    .
  10. ISBN 978-81-203-2892-1
    .
  11. ^ "Research Group on The December 26, 2004 Earthquake Tsunami Disaster of Indian Ocean". Drs.dpri.kyoto-u.ac.jp. Archived from the original on April 12, 2010. Retrieved 2010-10-26.
  12. S2CID 135197944
    .
  13. ^ a b c IISEENET (Information Network of Earthquake disaster Prevention Technologies). "Search Parameters". Retrieved 2009-11-04.
  14. doi:10.1785/0120010106
    . Retrieved 25 November 2010.
  15. ^ "Magnitude 7.4 - SIMEULUE, INDONESIA". earthquake.usgs.gov. Archived from the original on 2010-01-15.
  16. ^ "Magnitude 7.2 - KEPULAUAN MENTAWAI REGION, INDONESIA". Archived from the original on 2010-01-15. Retrieved 2015-10-01.
  17. ^ "Magnitude 7.2 - NORTHERN SUMATRA, INDONESIA". Archived from the original on 2010-05-11. Retrieved 2015-10-01.
  18. ^ "Magnitude 7.2 - OFF THE WEST COAST OF NORTHERN SUMATRA". earthquake.usgs.gov. Archived from the original on 2012-01-13.
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