This research is to utilize digitized core phases PKP generated by earthquakes to study the inner core where some evidence of anisotropy has been found, and the core-mantle boundary where heterogeneity is known but poorly resolved. Data are extracted from CD-ROMS distributed by the National Earthquake Information Center and from the IRIS data center. In order to remove effects of mantle hetereogeneities and earthquake source mislocations, the research will utilize differential measurements between phases with similar paths in the mantle. Both amplitudes and times will be used to analyze inner core structure along the earth's spin axis. The results will be used to constrain theories of anisotropy and heterogeneity in the inner core and core-mantle boundary regions.
