Lithospheric and upper mantle structure of the Indian Shield, from teleseismic receiver functions

Abstract

Receiver functions derived from teleseismic P waveforms of 297 earthquakes recorded at broadband station Hyderabad (HYB) are analysed to investigate the lithospheric and upper mantle structure in the vicinity of the station, located in the northeastern part of the Archaean Dharwar Craton. The internal structure of the 33±2 km thick crust is simple. It can be approximated by a single layer with S velocity linearly increasing with depth from 3.4 to 4.0 km/s, the average being 3.7±0.2 km/s. The crustal Poisson's ratio is 0.25±0.01. A seismic discontinuity at 90 km depth is inferred from a signal particularly prominent on the SH component and possibly indicative of a layer of depth-localized anisotropy in the lithospheric mantle. The two principal mantle discontinuities are at depths of 406 and 659 km, which are close to the global averages.