Shear velocity structure of the South-West Indian Ocean using Rayleigh wave

The dominant feature on the seismogram of shallow earthquakes is the Rayleigh wave, which can be used to deduce the shear velocity structure of the Earth, particularly the Lithosphere. In this study, we use Rayleigh waves from 356 paths that traverse through the Mozambique Ridge, Lwandle Plate and Madagascar Ridge in the South-West Indian Ocean. The fundamental mode Rayleigh wave group velocity is calculated between 13 and 120 sec using multi-filter technique (MFT) and then inverted for 1D shear velocity structure along the source-receiver path using damped least square method. The lowest group velocity of 2.6 km/s observed at 13 sec and the highest group velocity of 3.96 km/s was observed at 60 sec respectively. The estimated thicknesses of the crust, lithosphere and asthenosphere beneath the studied region of the South-West Indian Ocean, are respectively 23 km, 60 km, and 283 km. The variations of shear velocities and the layer thickness from our study, indicates that the structures beneath the ray paths are quasi-continental and deformed.