A 3D Shear Wave Velocity Structure of the Lithosphere‐Asthenosphere System Beneath the Indian Ocean

Abstract The structure of the lithosphere‐asthenosphere system beneath the Indian Ocean remains one of the most enigmatic and complex frameworks among the world's oceans due to relatively limited seismic data coverage and intricate tectonic settings. This study presents the regional tomography model (24), which provides a 3D shear‐wave velocity structure for the entire Indian Ocean with a lateral resolution of 200–600 km, down to a depth of 300 km. In this model, we inverted the regionalized local group velocities, obtained from 32,000 high‐quality dispersion data spanning a period range of 18–180 s using a trans‐dimensional inversion approach. This model shows excellent correlation with surface tectonics and accurately delineates significant features such as mid‐oceanic ridges, Sunda subduction zone (SSZ), and low‐velocity zones in the eastern and western sides of the Indian Ocean. Intriguingly, our model and tectonic regionalization results identify a distinct low‐velocity anomaly oriented in the SW‐NE direction with localized strong low‐velocity anomaly/reservoir in the north‐eastern side within the Indo‐Australian diffusion plate boundary (IADPB) zone. This observation concurs with seafloor age data, suggesting a relatively younger age (40 Ma) in this region compared to its surroundings. The strong low‐velocity anomaly/reservoir within the IADPB zone on the western side of the SSZ could be due to the accumulation of asthenospheric material from ridges, which are ultimately fed by super plumes along with upwellings from the deep‐seated sources beneath the region. These seismological findings strongly suggest ongoing active dynamics in this region.