Multi-scale imaging and modelling of seismic reflectors

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Seismic waves reflect and scatter at abrupt changes in the physical properties of the Earth's interior. Because waves travel to the surface, an image of these changes can be created from information contained in recorded seismic signals. Seismic imaging commits itself to identifying this information and relating it back to its origin, the abrupt changes in the interior. Not only can the location of these abrupt changes be found but also important information about the geological, geophysical and mineralogical processes. Examples of seismically observed discontinuities include the 410- and 660-km discontinuities in the upper mantle, the crust-mantle boundary and reflections from the upper sedimentary crust. Only by using advanced techniques from theoretical signal processing and applied mathematics can detailed information be obtained about the precise nature of discontinuities from incomplete and noisy seismic data. With this information a new classification according to abruptness can be made by means of exponents. These exponents complement the information normally being recovered from seismic images and they provide crucial new information on the sedimentary and mineralogical processes that are responsible for the creation of seismic discontinuities. Critical phenomena that mark the onset of connectivity give rise to exponents. Information obtained by new wavelet-based estimation techniques to be developed through this proposal will provide the necessary information to better constrain models of these phenomena. The study of critical phenomena at discontinuities opens new ways of recovering information on the composition of the Earth's subsurface by using the latest imaging techniques.