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Title: Shear velocity structure of the India-Asia collision zone
Author: Acton, C. E.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2009
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This dissertation describes the use of a number of seismic techniques to probe further the crustal and uppermost mantle shear velocity structure of the collision zone and the undeformed Indian shield to the south. A study of Rayleigh wave fundamental mode group velocity dispersion curves for 4054 receiver-source paths across India, Tibet and surrounding regions is used to obtain high-resolution group velocity maps between 10s and 70s. The dataset provides a higher frequency content than previous global studies and, with the inclusion of long paths up to ~5000km, bridges the gap between regional and global studies. This provides better constraints on whole crustal structure. Higher frequency P to S receiver functions are used to resolve the position of the major interface beneath seismic stations across the region; most importantly the crust-mantle boundary. Joint inversion of receiver function data and group velocity dispersion data limits the non-uniqueness inherent in receiver function inversion which is highly sensitive to a depth-velocity trade-off. The receiver function study is divided into two parts, defined by geographical area. Firstly, data from a number of broadband stations deployed over the course of this research in West Bengal and Sikkim are analysed alongside data from the INDEPTHII deployment which provides a northwards extension of the profile into Tibet. Data from previous experiments in nearby Nepal and Bhutan are studied in order to give a more complete picture of the crustal structure of this region of the Himalayas. Secondly, receiver function data for a large number of stations across the South Indian shield are revisited to provide an improved and coherent picture of variations in crustal thickness across the different geological terrains. Finally, dispersion curves extracted from the series of group velocity maps produced for the region are inverted for shear velocity structure.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available