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Title: Modelling shear-wave anisotropy in the Paris Basin
Author: Bush, Iain
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1990
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This thesis examines shear-wave propagation in the Paris Basin and demonstrates that the sedimentary rocks must have, at least, an orthorhombic anisotropic symmetry. It is suggested that the most likely cause of such an orthorhombic symmetry is the combination of fine-layering and crack anisotropy. Observations from two near-offset VSPs indicate the large variation of shear-wave delay expected for propagation directions close to a point singularity, and constitute probably the first recognition of the effects of a singularity in observed data. However, lateral variations of crack density in the near-surface could also account for this observation and thus, without further geological information about the near-surface, it cannot definitely be concluded that the anomalous low delay at one VSP is due to singularity. A transition zone (close to a singularity) where there are rapid changes of shear-wave polarization and delay can account for the anomalous motions observed on the wide-offset VSPs.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available