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sparse representation, seismic source parameter inversion, time-frequency analysis, compressive sensing, resolution analysis, noise attenuation, group sparsity, source mechanism inversion

Vera Rodriguez, Ismael A.

Supervisor and department: Sacchi, Mauricio Physics Gu, Yu Physics

Examining committee member and department: Schmitt, Douglas Physics Vorobyov, Sergiy Electrical and Computer Engineering van der Baan, Mirko Physics Bostock, Michael Earth, Ocean and Atmospheric Sciences, University of British Columbia

Department: Department of Physics

Specialization: Geophysics

Date accepted: 2012-08-16T15:48:25Z

Graduation date: 2012-11

Degree: Doctor of Philosophy

Degree level: Doctoral

Abstract: Seismic events can be characterized by its origin time, location and moment tensor. Fast estimations of these source parameters are important in areas of geophysics like earthquake seismology, and the monitoring of seismic activity produced by volcanoes, mining operations and hydraulic injections in geothermal and oil and gas reservoirs. Most available monitoring systems estimate the source parameters in a sequential procedure: first determining origin time and location e.g., epicentre, hypocentre or centroid of the stress glut density, and then using this information to initialize the evaluation of the moment tensor. A more efficient estimation of the source parameters requires a concurrent evaluation of the three variables.The main objective of the present thesis is to address the simultaneous estimation of origin time, location and moment tensor of seismic events. The proposed method displays the benefits of being: 1 automatic, 2 continuous and, depending on the scale of application, 3 of providing results in real-time or near real-time. The inversion algorithm is based on theoretical results from sparse representation theory and compressive sensing. The feasibility of implementation is determined through the analysis of synthetic and real data examples. The numerical experiments focus on the microseismic monitoring of hydraulic fractures in oil and gas wells, however, an example using real earthquake data is also presented for validation. The thesis is complemented with a resolvability analysis of the moment tensor. The analysis targets common monitoring geometries employed in hydraulic fracturing in oil wells. Additionally, it is presented an application of sparse representation theory for the denoising of one-component and three-component microseismicity records, and an algorithm for improved automatic time-picking using non-linear inversion constraints.

Language: English

DOI: doi:10.7939-R3PK7K

Rights: Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.

Autor: Vera Rodriguez, Ismael A.



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