• A note on stress rotations due to the 2004 $M_{\rm{w}}$ 9.2 Sumatra–Andaman megathrust earthquake

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      https://www.ias.ac.in/article/fulltext/jess/129/0187

    • Keywords

       

      Subduction zones; megathrust earthquakes; stress rotations.

    • Abstract

       

      Here we study the evolution of stress and its rotations in the Sumatra–Andaman Subduction Zone (SASZ) after the 2004 $M_{\rm{w}}$ 9.2 megathrust earthquake, using moment tensor stress inversions. Models indicate returning of North Andaman stress regime to the inter-seismic oblique-compression, after a short stint of extension. Likewise, Little Andamans experience extension indicating a trench-ward guidance of extensional stresses. Similarly, Nicobar regime is presently normal-oblique, from early post-seismic reverse-oblique, and North Sumatra experiences pure-reverse regime. The influence of the Wharton Basin stress field and 2012 earthquakes on the SASZ fore-arc deformation is also probed. A near-complete co-seismic stress-relief is observed at Nicobar, followed by North Sumatra and Little Andaman. Co-seismic and post-seismic model comparisons indicate strong correlation with zones of co-seismic stress relief and regions of rapid post-seismic reloading. The North Andaman shows a northward compressive shear than the margin-normal component of subduction, as evident from prominent oblique stress regime with lower co-seismic stress relief and lack of post-seismic back rotations. At Andaman Spreading Ridge (ASR), transition from oblique to extensional stress indicates lateral shear to back-arc spreading enhancement.

    • Author Affiliations

       

      SILPA K1 2 ANIL EARNEST1 2

      1. Academy of Scientific and Innovative Research, CSIR Fourth Paradigm Institute, Wind Tunnel Road, Bangalore, Karnataka, India.
      2. Multi-scale Modelling Programme, CSIR Fourth Paradigm Institute, Wind Tunnel Road, Bangalore, Karnataka, India.
    • Dates

       
  • Journal of Earth System Science | News

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