Iterative Optimization Methods
Introduction to Seismic Inversion: Seismic inversion, or tomography, is the procedure for reconstructing earth properties from seismic data. The tomogram is presented graphically as a two- or three-dimensional (2D or 3D) grid of pixels, in which each pixel contains the model parameter of interest, such as the velocity value or its reciprocal value known as slowness. An example is shown in Figure 1.1, which is a vertical slice of a 3D tomogram inverted from first-arrival traveltimes picked from seismic data. These arrivals are assumed to propagate mostly along the dashed raypaths (see Figure 1.2a) from the source at s to the geophone g, and they are recorded as a seismic trace. An actual set of traces recorded for one shot is shown in Figure 1.2b, and Figure 1.3 depicts several rays associated with different types of events. Appendix 1A provides an overview of exploration seismology.