This research is to develop a new theoretical approach to the inversion of seismic wave-form data for determination of spatial distributions of medium properties. The new approach is based on the renormalized source-type integral equation method recently proposed for inversion of electric field data to determine the 1- D conductivity profile. This research will attempt to extend the new approach to the acoustic wave data to determine the 2-D and 3- D velocity and density structure, in which the back-ground medium is assumed to be vertically (1-D) heterogeneous. The new approach is expected to be superior to the usual linearization-iteration procedure based on the first Born approximation.
