Abstract

The crustal tomographic image is obtained toward south of SGT, India using deep seismic sounding data along 220 km N-S Vattalkundu-Kanyakumari profile acquired in 2005. The image depicts both subsurface structural and velocity heterogeneities along with numerous shear zones. The crust is thickest near Vattalkundu (44 km) and gradually thins toward Kanyakumari (36 km) with intracrustal undulations. The P-wave velocities for upper and lower crust range from 6.0-6.4 km/s and 6.7-7.1 km/s, respectively. The thick crust (>40 km) with high average velocity (>6.7 km/s) and high heat-flow (~58 mW/m2 ) indicates complex tectonothermal evolution of the region. The Bouguer gravity data also show anomalous signatures near the Achankovil shear zone and the density model derived corroborates both preferred and tomographic velocity models.