Waveform tomography

Abstract

Why use delay times only? Obviously, a seismogram contains much more information than the arrival time of the first wavelet, and we should wish to include the whole seismic time series in the data set, and use this in an imaging technique. There are two obstacles to such an approach. The first is the enormity of the numerical problem. The second is that it is often difficult or impossible to develop a manageable approximation to the solution of the wave equation, especially one that is adequate enough to model the response of complicated Earth models. This chapter deals with the first question in general, and with the second for the case of low frequency seismic waves with relatively low horizontal phase velocity.