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Document Description
TitleOn forward and inverse modelling in seismology: raytracing in inhomogeneous media
AuthorSmith, Peter M., 1982-
DescriptionThesis (M.Sc.)--Memorial University of Newfoundland, 2006. Earth Sciences
Paginationxvii, 137 leaves : ill. + 1 CD-ROM (4 3/4 in.)
SubjectInhomogeneous materials; Simulated annealing (Mathematics); Seismic waves--Mathematical models
Degree GrantorMemorial University of Newfoundland. Dept. of Earth Sciences
DisciplineEarth Sciences
NotesBibliography: leaves 115-116. Link to CD-ROM materials included in the sidebar, at the end of the thesis. Pages [vi], [xii], [xvi], [xviii], [122] and [136] are blank and have been omitted from the digital reproduction.
AbstractThe first part of this thesis deals with forward modelling. We present a raytracing method based on the concept of simulated annealing: a computational tool based on physical principles used for obtaining optimal solutions of problems of in areas ranging from combinatorics to condensed matter physics. Our method solves for rays that render signal traveltime stationary, in accordance with Fermat's principle of stationary traveltime. We test this method for two types of media: layered inhomogeneous media and linearly inhomogeneous media. We show that rays and traveltimes generated from this algorithm for these models quantitatively agree with predicted results. -- The second part of the thesis deals with inverse modelling. In this part, we introduce the generalized form of Radon's transform and its adjoint operator. We show that by treating traveltime as Radon's transform acting on the slowness function along a ray, we can use the adjoint operator to recover qualitative information about a medium from collected traveltimes. This method of backprojection is presented as an application of our raytracing method. We calculate rays and their associated traveltimes between sources and receivers on a square lattice for layered- and linearly-inhomogeneous media and use the back-projection method to construct slowness functions for each set of data. We show that although the backprojection method does not retain the quantitative properties of the original medium, results indicate that qualitative properties of the medium can be resolved by this method.
Resource TypeElectronic thesis or dissertation
FormatImage/jpeg; Application/pdf
SourcePaper copy kept in the Centre for Newfoundland Studies, Memorial University Libraries
Accompanying Files
Local Identifiera2054263
RightsThe author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission.
CollectionElectronic Theses and Dissertations
Scanning StatusCompleted
PDF File(23.03 MB) --
CONTENTdm file name65765.cpd