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En échelon and orthogonal fault ruptures of the 11 April 2012 great intraplate earthquakes

Abstract

The Indo-Australian plate is undergoing distributed internal deformation caused by the lateral transition along its northern boundary—from an environment of continental collision to an island arc subduction zone1,2. On 11 April 2012, one of the largest strike-slip earthquakes ever recorded (seismic moment magnitude Mw 8.7) occurred about 100–200 kilometres southwest of the Sumatra subduction zone. Occurrence of great intraplate strike-slip faulting located seaward of a subduction zone is unusual. It results from northwest–southeast compression within the plate caused by the India–Eurasia continental collision to the northwest, together with northeast–southwest extension associated with slab pull stresses as the plate underthrusts Sumatra to the northeast. Here we use seismic wave analyses to reveal that the 11 April 2012 event had an extraordinarily complex four-fault rupture lasting about 160 seconds, and was followed approximately two hours later by a great (Mw 8.2) aftershock. The mainshock rupture initially expanded bilaterally with large slip (20–30 metres) on a right-lateral strike-slip fault trending west-northwest to east-southeast (WNW–ESE), and then bilateral rupture was triggered on an orthogonal left-lateral strike-slip fault trending north-northeast to south-southwest (NNE–SSW) that crosses the first fault. This was followed by westward rupture on a second WNW–ESE strike-slip fault offset about 150 kilometres towards the southwest from the first fault. Finally, rupture was triggered on another en échelon WNW–ESE fault about 330 kilometres west of the epicentre crossing the Ninetyeast ridge. The great aftershock, with an epicentre located 185 kilometres to the SSW of the mainshock epicentre, ruptured bilaterally on a NNE–SSW fault. The complex faulting limits our resolution of the slip distribution. These great ruptures on a lattice of strike-slip faults that extend through the crust and a further 30–40 kilometres into the upper mantle represent large lithospheric deformation that may eventually lead to a localized boundary between the Indian and Australian plates.

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Figure 1: The 11 April 2012 rupture sequence.
Figure 2: Short-period seismic energy release pattern.
Figure 3: Long-period seismic energy release pattern.
Figure 4: Map of primary faulting during the M w 8.7 event.

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References

  1. Minster, J. B. & Jordan, T. H. Present day plate motions. J. Geophys. Res. 83, 5331–5354 (1978)

    Article  ADS  Google Scholar 

  2. Wiens, D. et al. A diffuse plate boundary model for Indian Ocean tectonics. Geophys. Res. Lett. 12, 429–432 (1985)

    Article  ADS  Google Scholar 

  3. Gordon, R. G., DeMets, C. & Argus, D. F. Kinematic constraints on distributed lithospheric deformation in the equatorial Indian Ocean from present motions between the Australian and Indian plates. Tectonics 9, 409–422 (1990)

    Article  ADS  Google Scholar 

  4. Gordon, R. G. DeMets, C. & Royer, J.-Y. Evidence for long-term diffuse deformation of the lithosphere of the equatorial Indian Ocean. Nature 395, 370–374 (1998)

    Article  CAS  ADS  Google Scholar 

  5. Royer, J.-Y. & Gordon, R. G. The motion and boundary between the Capricorn and Australian plates. Science 277, 1268–1274 (1997)

    Article  CAS  Google Scholar 

  6. Stein, S. & Okal, E. A. Seismicity and tectonics of the Ninetyeast Ridge area, evidence for internal deformation of the Indian Plate. J. Geophys. Res. 83, 2233–2245 (1978)

    Article  ADS  Google Scholar 

  7. Delescluse, M. & Chamot-Rooke, N. Instantaneous deformation and kinematics of the India-Australia plate. Geophys. J. Int. 168, 818–842 (2007)

    Article  ADS  Google Scholar 

  8. DeMets, C. & Royer, J.-Y. A new high-resolution model for India-Capricorn motion since 20 Ma: implications for the chronology and magnitude of distributed crustal deformation in the Central Indian Basin. Curr. Sci. 85, 339–345 (2003)

    Google Scholar 

  9. Robinson, D. P., Henry, C., Das, S. & Woodhouse, H. H. Simultaneous rupture along two conjugate planes of the Wharton Basin earthquake. Science 292, 1145–1148 (2001)

    Article  CAS  ADS  Google Scholar 

  10. Abercrombie, R. E., Antolik, M. & Ekström, G. The June 2000 Mw 7.9 earthquakes south of Sumatra: deformation in the India-Australia Plate. J. Geophys. Res.. 108 (B1), 2018, http://dx.doi.org/10.1029/2001JB000674 (2003)

  11. McGuire, J. J. & Beroza, G. C. A rogue earthquake off Sumatra. Science 336, 1118–1119 (2012)

    Article  CAS  ADS  Google Scholar 

  12. Kanamori, H. The energy release in great earthquakes. J. Geophys. Res. 82, 2981–2987 (1977)

    Article  ADS  Google Scholar 

  13. Ben-Menahem, A., Aboodi, E. & Schild, R. The source of the great Assam earthquake — an interplate wedge motion. Phys. Earth Planet. Inter. 9, 265–289 (1974)

    Article  ADS  Google Scholar 

  14. Chen, W.-P. & Molnar, P. Seismic moments of major earthquakes and the average rate of slip in Central Eurasia. J. Geophys. Res. 82, 2945–2969 (1977)

    Article  ADS  Google Scholar 

  15. Molnar, P. A review of the seismicity and the rates of active underthrusting and deformation at the Himalayas. J. Himal. Geol. 1, 131–154 (1990)

    Google Scholar 

  16. Pollitz, F. F., Stein, R. S., Sevilgen, V. & Bürgmann, R. The 11 April 2012 east Indian Ocean earthquake triggered large aftershocks worldwide. Nature http://dx.doi.org/nature11504 (this issue).

  17. Ammon, C. J. et al. Rupture process of the 2004 Sumatra-Andaman earthquake. Science 308, 1133–1139 (2005)

    Article  CAS  ADS  Google Scholar 

  18. Delescluse, M. et al. April 2012 intra-oceanic seismicity off Sumatra boosted by the Banda–Aceh megathrust. Nature http://dx.doi.org/nature11520 (this issue).

  19. Shapiro, N. M., Ritzwoller, M. H. & Engdahl, E. R. Structural context of the great Sumatra-Andaman Islands earthquake. Geophys. Res. Lett. 35, L05301, http://dx.doi.org/10.1029/2008GL033381 (2008)

    Article  ADS  Google Scholar 

  20. Ishii, M., Shearer, P. M., Houston, H. & Vidale, J. E. Extent, duration and speed of the 2004 Sumatra-Andaman earthquake imaged by the Hi-net array. Nature 435, 933–936 (2005)

    Article  CAS  ADS  Google Scholar 

  21. Krüger, F. & Ohrnberger, M. Tracking the rupture of the Mw 9.3 Sumatra earthquake over 1,150 km at teleseismic distance. Nature 435, 937–939 (2005)

    Article  ADS  Google Scholar 

  22. Koper, K. D., Hutko, A. R., Lay, T. & Sufri, O. Imaging short-period seismic radiation from the 27 February 2010 Chile (Mw 8.8) earthquake by back-projection of P, PP, and PKIKP waves. J. Geophys. Res. 117, B02308, http://dx.doi.org/10.1029/2011JB008576 (2012)

    Article  ADS  Google Scholar 

  23. Koper, K. D., Hutko, A. R. & Lay, T. Along-dip variation of teleseismic short-period radiation from the 11 March 2011 Tohoku Earthquake (Mw 9.0) Geophys. Res. Lett. 38, L21309, http://dx.doi.org/10.1029/2011GL049689 (2011)

    Article  ADS  Google Scholar 

  24. Incorporated Research Institutions for Seismology. Back projections for Mw 8. 7 off W coast of Northern Sumatra, http://www.iris.edu/spud/backprojection/118733 (2012)

  25. Meng, L., Ampuero, J.-P. & Luo, Y. Back-projection results, 4/11/2012 (Mw8.6) offshore Sumatra, Indonesia. http://www.tectonics.caltech.edu/slip_history/2012_Sumatra/back_projection/

  26. Kiser, E. Preliminary rupture modeling of the April 11, 2012 Sumatran earthquakes. http://www.seismology.harvard.edu/research_sumatra2012.html

  27. Wang, D., Mori, J. & Ohmi, S. Rupture process of the April 11, 2012 Sumatra (Mw 8.6) earthquake imaged with back-projection of Hi-net data. http://www.eqh.dpri.kyoto-u.ac.jp/src/etc/sumatra.htm.

  28. Lay, T. et al. Depth-varying rupture properties of subduction zone megathrust faults. J. Geophys. Res. 117, B04311, http://dx.doi.org/10.1029/2011JB009133 (2012)

    Article  ADS  Google Scholar 

  29. Lay, T. et al. The 2006–2007 Kuril Islands great earthquake sequence. J. Geophys. Res. 114, B11308, http://dx.doi.org/10.1029/2008JB006280 (2009)

    Article  ADS  Google Scholar 

  30. Duputel, Z. et al. The 2012 Sumatra great earthquake sequence. Earth Planet. Sci. Lett. 351-352, http://dx.doi.org/10.1016/j.epsl.2012.07.017 (2012)

  31. Hjörleifsdóttir, V., Kanamori, H. & Tromp, J. Modeling 3-D wave propagation and finite slip for the 1998 Balleny Islands earthquake. J. Geophys. Res. 114, B03301, http://dx.doi.org/10.1029/2008JB005975 (2009)

    Article  ADS  Google Scholar 

  32. Meng, L. et al. Earthquake in a maze: compressional rupture branching during the 2012 Mw 8.6 Sumatra earthquake. Science 337, 724–726 (2012)

    Article  CAS  ADS  Google Scholar 

  33. Xu, Y., Koper, K. D., Sufri, O., Zhu, L. & Hutko, A. R. Rupture imaging of the Mw 7.9 12 May 2008 Wenchuan earthquake from back projection of teleseismic P waves. Geochem. Geophys. Geosyst. 10, Q04006 (2009)

    ADS  Google Scholar 

  34. Kennett, B. L. N., Engdahl, E. R. & Buland, R. Constraints on seismic velocities in the Earth from travel times. Geophys. J. Int. 122, 108–124 (1995)

    Article  ADS  Google Scholar 

  35. VanDecar, J. C. & Crosson, R. Determination of teleseismic relative phase arrival times using multi-channel cross-correlation and least squares. Bull. Seismol. Soc. Am. 80, 150–159 (1990)

    Google Scholar 

  36. Velasco, A. A., Ammon, C. J. & Lay, T. Empirical Green function deconvolution of broadband surface waves: Rupture directivity of the 1992 Landers, California (Mw 7.3) earthquake. Bull. Seismol. Soc. Am. 84, 735–750 (1994)

    Google Scholar 

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Acknowledgements

We thank H. Kanamori, Z. Duputel and G. Hayes for discussions and exchanges of information about this event. A. Hutko provided early short-period back-projection results. We thank R. Abercrombie for comments on this paper. This work made use of GMT and SAC software and Federation of Digital Seismic Networks (FDSN) seismic data. The Incorporated Research Institutions for Seismology (IRIS) Data Management System (DMS), the European ORFEUS Data Center and the NIED F-net Data Centre were used to access the data. This work was supported by NSF grant EAR0635570 (T.L.) and EAR0951558 (K.D.K.).

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Contributions

H.Y. contributed to the surface wave back-projections and finite fault modelling; K.D.K. performed the short-period back-projections; and T.L. performed finite-fault inversions and guided the synthesis.

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Correspondence to Thorne Lay.

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Supplementary information

Supplementary Information

This file contains Supplementary Figures 1-7 and full legends for Supplementary Movies 1 -2. (PDF 2244 kb)

Supplementary Movie 1

This movie shows animations of the short-period back-projections from European and Japanese (F-net) stations for the Mw 8.7 event - see Supplementary Information file for full legend. (MOV 4839 kb)

Supplementary Movie 2

This movie shows animations of the short-period back-projections from European and Japanese (F-net) stations for the Mw 8.2 event - see Supplementary Information file for full legend. (MOV 3512 kb)

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Yue, H., Lay, T. & Koper, K. En échelon and orthogonal fault ruptures of the 11 April 2012 great intraplate earthquakes. Nature 490, 245–249 (2012). https://doi.org/10.1038/nature11492

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