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Title: Surface wave propagation and lithospheric structure
Author: Barron, J. A. A.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2010
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In this dissertation, I develop and use seismological techniques for elucidating details of the upper mantle structure of the Earth. This thesis is divided into two studies. In the first, I develop surface wave tomographic models of Europe based on data from the analysis of the fundamental and first four higher Rayleigh wave modes. I use an automated waveform inversion technique to extract path-average mantle velocity models, which are then combined in a 3-dimensional tomographic inversion for upper mantle shear velocity structure. The automated waveform inversion scheme is based on that of Debayle (1999), and I develop and extend this to include shorter period information, and to allow the automated processing of large quantities of seismic data on a computer cluster. I present models inverted using periods in the range 50-160 s, as used by a number of previous studies which used this technique to image upper mantle structure in other regions, and also in the range 30-150 s. By conducting synthetic tests, I find that the inclusion of the shorter period information improves the vertical resolution of the tomography. The inclusion of short period information is an important step towards improving the resolution of surface wave tomography in the shallow part of the upper mantle. The images of Europe developed give some insight into the complex tectonic features in the region. In the second part of this dissertation, I present observations of the frequency-dependent propagation efficiency of the seismic phase Sn over the Tibetan Plateau. I measure the ratio of the Sn amplitude to the Pg coda amplitude on Tibetan regional seismograms, and map the lateral variation in the maximum and mean values of this ratio across the Plateau.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available