Polarization analysis of multi-component data from a single station or antenna: methods and applications to seismic wave field characterization.

Summary The analysis of the wave field is an essential prerequisite to the study of seismic wave propagation, which in turn improves our understanding of the physical processes related to the nature of the source and our knowledge of the propagation media. The objective of this thesis is to develop signal processing techniques to improve the exploitation of the information provided by the stations and 3-component antennas in order to characterize the seismic wave field. It focuses on polarization analysis, its extension to 3-component antennas and its use in conjunction with conventional antenna processing. The thesis reviews existing approaches that attempt to extend antenna processing to 3 components. These existing methods are complex and their use remains limited, the thesis suggests two alternative methods combining successively antenna processing and polarization. In order to make the best use of the polarization analyses, a standardized system of parameters describing the polarization is developed and associated with a visualization solution allowing to group all the parameters essential to the interpretation on a single figure. Finally, a polarization study on the LSBB (Laboratoire Souterrain Bas Bruit) 3-component antenna demonstrates the possibility of using the spatial coherence of the polarization as an aid for the interpretation of seismograms.