Material properties from seismic measurements

Abstract:In this presentation, I will discuss several aspects of my work conducted in the last decade as head of a research group and Chair of Applied Seismology at Memorial University. In view of the multidisciplinary nature of this work, its results have been published in geophysical, mechanical, mathematical and computational journals. Herein, I propose to make an overview of these results. Obtaining information about the subsurface --- in particular, about its material properties --- must be based on relating measurements to these properties via theories expressed in the mathematical language. The more applicable the theory, the more sophisticated the mathematics needed to express it (and not the other way around, as commonly believed). This apparent irony is due to our wish to reduce the number of idealizations, which is tantamount to formulating more detailed theories. With this in mind, I will discuss the following topics: -- idealization of a Hookean solid, and related anisotropy and inhomogeneity -- obtaining information about symmetries of materials with as few assumptions as possible -- drawing conclusions based on a Hookean model while taking into account the actual data versus idealized model The spirit of the presentation is to relate the necessarily abstract formulation to the observables in order to shed light on the physical properties of the subsurface. ----------------------------------------------------------------------------- Séminaire de Géosciences Marines -----------------------------------------------------------------------------