Bridging the gap between subduction dynamics and the long-term strength of the Sunda megathrust
Subduction zone forces strongly influence tectonic stresses and earthquake behaviour along convergent margins. In the Sunda region (Java–Sumatra–Andaman), variations in slab pull and mantle flow control how plates move and interact. Using high-resolution 3-D models that match present-day observations, we show that the pull of the Java slab dominates regional dynamics, driving northward-increasing oblique convergence, trench advance near Sumatra, and stronger plate coupling. The modelled stress patterns agree with geodetic data and earthquake stress orientations. Frictional strength variations along the megathrust identify key depth zones that align with major earthquake locations, highlighting how deep subduction processes set conditions for seismic events.
a) Mantle flow at 300 km depth in Model 1. Arrows for horizontal flow velocities, in color for the vertical velocity. b) Mantle flow streamlines, in color for the vertical velocity. Positive vertical velocities represent mantle upwelling, whereas negative vertical velocities indicate mantle downwelling. In dark green the subducting lithosphere and blue for the subducting slab. Lower mantle in light green. a) was created with open-source software Python and library Matplotlib, b) with open-source software Paraview.
Research Tags
Associated Publication
Bridging the gap between subduction dynamics and the long-term strength of the Sunda megathrust
Fabio A. Capitanio, Thyagarajulu Gollapalli, Radhakrishna Munukutla, Juan Carlos Graciosa, Zuhair Mohd, Adam Beall, Luca Dal Zilio
DOI10.1038/s41467-025-65824-7
Abstract
The link between great earthquakes and subduction dynamics across a wide range of scales remains a crucial, yet elusive, tenet of the seismotectonics of convergent margins. Here, we show high-performance computational simulations of the three-dimensional Sunda subduction zone dynamics matching plate motions, tectonics and current deformation, thereby providing insights into the stress regime of the Java-Sumatra-Andaman margin. Testing various tectonic forces reveals the primary control of the Java slab pull and induced mantle flow on the whole margin tectonics, driving northward-increasing oblique convergence, Sumatran trench advance and increased tectonic coupling along this segment. The modelled deviatoric stresses reproduce the geodetically-constrained interseismic compression in Sumatra and megathrust stress orientations notably consistent with the seismic P-axes, with magnitude comparable to static stresses on seismogenic faults. We map the frictional strength along the Sumatra-Andaman megathrust, identifying critical thresholds at key seismogenic depths, which remarkably correlate with the location of great earthquakes. Our outcomes show how subduction dynamics may critically prime the conditions for seismicity along the Sunda margin.
Compute Tags
None specified.
Software
Software information not available.
Model Setup
Setup of Model 1, 2 and 3. The models consist of a subducting plate with an attached slab, upper plate, upper mantle, and lower mantle. The mantle depth is 1000 km in (A) and (B), and 2891 km in (C). The thickness of the upper plate is 90 km in all models. The line with open squares indicates the trace of the interface.
Source repository:
https://github.com/ModelAtlasofTheEarth/gollapalli-2025-sundamegathrust
Citation
Gollapalli, T. (2026). Bridging the gap between subduction dynamics and the long-term strength of the Sunda megathrust [Data set]. AuScope, National Computational Infrastructure. https://doi.org/an8s-6g97
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Funders
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