Crustal structure of the Indian Shield: New constraints from teleseismic receiver functions

Teleseismic earthquake waveform data from 10 broadband stations spread over the Indian shield and in operation since 1997, were analyzed to infer the crustal structure, using the receiver function technique. The South Indian shield is characterized by a 33-39 km thick, and remarkably simple crust, w ith an average Poisson's ratio close to 0.25. The Archaean crust is devoid of any prominent intra-crustal discontinuities. The velocity contrast at th e well developed Moho is large, resulting in very clear P-to-S conversions as well as first-order multiples. In contrast, the predominantly Proterozoi c crust in the northern part of the shield exhibits a complex character, du e to the presence of additional seismic discontinuities. Moho conversions, which are considerably weaker compared to the Archaean terrains, indicate c rustal thicknesses of more than 40 km.