Flexural Analysis Along the Sunda Trench: Bending, Buckling and Plate Coupling

G. Raghuram, Fabio A. Capitanio, M. Radhakrishna

Research output: Contribution to journalArticleResearchpeer-review

6 Citations (Scopus)


The bathymetry and free-air gravity data offshore Sunda trench are used here to analyze the flexural forebulge and bending moment variations along the Southeast Asian subduction zone. The observed bathymetry is corrected for various effects such as the sediment loading, lithosphere age, and the gravity-derived isostatically compensated topography, which gave rise to the flexural deformation surface of the subducting Indo-Australian plate. From this, 28 across-trench sections were constructed to model the plate flexural bending along the Sunda trench. We observed that except in the northern Sumatra trench, rest of the Sunda trench is in agreement with the flexural model explained by the bending moment applied by the slab. In the northern Sumatra part of the trench, additional horizontal stresses of ~30–40 MPa are required for better match of the flexural forebulge thereby increasing the coupling with the upper plate. The outcome of this analysis in comparison with the slab depth variation, which abruptly reduces from ~600 km in Java to ~200 km toward northern Sumatra, suggests that very large bending moment and horizontal stresses are anticorrelated with the slab depth. The shorter slab in Sumatra does not effectively pull the incoming plate in the mantle, and therefore, plate convergence is accommodated at shallow depth, increasing the coupling with the upper plate. We propose that horizontal stresses are the result of the lateral propagation of the stronger slab pull from the neighboring deeper southeastern Java slab.

Original languageEnglish
Pages (from-to)3524-3544
Number of pages21
Issue number10
Publication statusPublished - 1 Oct 2018


  • flexure analysis
  • plate coupling
  • subduction zone

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