סמינר בחוג לגיאופיזיקה: Time Reversal in seismic: theory and application

Abstract:

Time reversal (TR) is a fundamental physical concept, based on the wave equation’s invariance under time-reversal operation. If the recorded wave-field is time-reversed and back-propagated into the medium, it will focus at its original source location regardless of the complexity of the medium. We utilize this property for two seismic applications: velocity analysis and scatterer detection and localization. Velocity analysis is formulated as an inversion problem with focusing at the known source location and onset time as the objective function. This approach has the advantages of utilizing the wave equation, being picking-free and requiring neither information on the source wavelet nor an initial velocity model. Scattering objects can be effectively detected and positioned using the TR principle. Subsurface sources in passive seismic scenarios and scatterers in active seismic surveys, both having the physical properties of a point diffractor can be effectively localized using TR principles. The method uses numerical back propagation followed by an analysis of its obtained focusing, based on a supervised learning approach.

מארגן הסמינר: פרופ' איל חפץ