Seismological Research Progress on Tectonic Deformation and Magmatisc System in the Sumatran Oblique Subduction Zone

The Sumatra subduction zone, characterized by oblique subduction, ranks among the most tectonically and magmatically active regions on Earth. This unique dynamic regime has forged a suite of prominent geological features, including the large-scale strike-slip Great Sumatran Fault, recurrent and often devastating mega-earthquakes, and vigorous arc volcanism crowned by the Toba supervolcano. The collection of these phenomena establishes the region as an unparalleled natural laboratory for probing the fundamental couplings between plate tectonic dynamics, crustal deformation, and magmatic processes in an oblique convergence setting. Our recent integrated seismological studies provide new, multi-scale constraints on this system. Specifically, high-resolution seismic imaging reveals along-strike bending and morphologic complexity of the subducting slab, which directly modulates plate coupling and influences the nucleation segments of megathrust ruptures. Precise relocation of medium-sized earthquakes further refines the megathrust geometry and defines trench-parallel seismicity belts bracketing the seismogenic zone. The along-strike variations of these belts and the steeper dip angles of the down-dip belt are well correlated with strong gradients in slab geometry, controlling rupture distribution. Beneath the Toba volcanic area, our joint shear-wave velocity and attenuation model resolves a multi-level magma plumbing system with a distinct column–corridor–reservoir architecture. This system is co-located with fluid-rich fault zones, pointing to a tectonically mediated pathway for melt migration from the mantle wedge to shallow storage. These findings provide mechanistic links between regional geodynamics and localized hazard expression. Building on this foundation, our ongoing research integrates multidisciplinary observations towards a comprehensively investigation of the Sumatran subduction system and its surroundings. Through systematic global comparison, we aim to elucidate the dynamics of oblique subduction and its fundamental controls on continental deformation, volcanic evolution and the spatiotemporal patterns of major geological hazards.