The Crust‐Mantle Structure of the Indian Peninsula from Surface Wave Dispersion

Abstract

The observed variations of group velocity with period for fundamental Rayleigh and Love waves along two profiles, viz. Kodaikanal‐New Delhi and Kodaikanal‐Poona as well as along paths from a few epicentres in the neighbourhood of New Delhi to Kodaikanal have been used to determine the crust‐mantle structure of the Indian Peninsula. The periods range from 6 to 80 s for Rayleigh waves and from 11 to 97 s for Love waves. Structural models obtained show that the total crustal thickness is 41 km in the central part of the Peninsula and increases to 52 km in the Western Ghats region; at the same time the thickness of the granitic layer also increases from 12 to 16 km. It has been noted that the assumption of a simple isotropic mantle does not give satisfactory fit to both Rayleigh and Love waves data at higher periods. A satisfactory fit has been obtained by considering the mantle between depths 60 and 160 km to be anisotropic with SV velocity about 5 per cent less than SH velocity. Copyright © 1974, Wiley Blackwell. All rights reserved