9417862 Romanowicz This research is to conduct two studies which address geophysically important questions pertaining to the very deep structure of the earth, the core-mantle boundary and inner core, using diffracted S waves on the core-mantle boundary on the one hand, and a combination of body-wave data and free-oscillation data sensitive to inner core structure, on the other. The first is a systematic study of diffracted SV deep into the seismic shadow of the earth's core, especially at epicentral distances in excess of 107 degrees. This analysis should provide a substantial and new contribution to the study of lateral heterogeneity at the core-mantle boundary, so important to the understanding of core and mantle geodynamics. The second study addresses the important question of inner core anisotropy, and, more specifically the issue of reconciling PKP travel time and normal mode splitting data, both in terms of depth dependence of anisotropy and its proposed cylindrical symmetry around the earth's rotation axis. This study is relevant to the question of the compositional and physical nature of the inner core, its dynamics as well as its relation with processes in the outer core. *** ??
