This research is to analyze body wave phases recorded over a period of several months by a digital three-component local array operated in the Subandean Province and East Peru Basin above the zone of flat subduction and resubduction in the central Andes. The analysis will include a systematic interpretation and inversion of body wave seismograms making use of a recently developed technique for the deterministic calculation of synthetic seismograms. Dipping plate structures outside the region of flat subduction will be studied by means of 3-D ray tracing routines which incorporate conversions and reflections at first-order discontinuities. The Andean system offers unique opportunities for the study of many fundamental problems of continental dynamics including earthquake hazard, and the fine structure and properties of the subducting slab, the overriding lithosphere and the interface between them. This research is a component of the National Earthquake Hazard Reduction Program.