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Fragmented plates in Sumatra-Andaman subduction zone revealed by distinct mantle anisotropic directions.

Illa B, Kumar Prakash.

GEOPHYSICAL JOURNAL INTERNATIONAL

https://doi.org/10.1093/gji/ggaf378 

Subduction zones, where one tectonic plate descends beneath another, produce some of the most powerful earthquakes. In the Andaman-Sumatra region, we reveal significant variations in Pn-wave velocity and anisotropy that influence earthquake nucleation and rupture dynamics. Abrupt changes The strong coupling of the Sunda plate with the subducting oceanic slab likely caused the 2004 and 2005 megathrust events, with rupture termination near Simeulue Island due to abrupt material contrasts. Low Pn-velocity anomalies west of the Andaman Sea suggest a magma reservoir linked to the torn Indian oceanic slab.

Fig: Top- Cartoon depicting the fragmented plates in the study region. Bottom-Anisotropic Pn tomographic image showing anisotropic magnitudes superimposed on the Pn velocity model.

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