Test of the innermost inner core models using broadband PKIKP travel time residuals

Two different innermost inner core (IMIC) models have recently been proposed, each with different radii and different orientation and strength of anisotropy. In order to test these IMIC models, we have systematically assembled a high quality dataset of broadband PKIKP data in the epicentral distance range of 150 degrees to 180 degrees. Our new dataset consists of similar to 1,100 individually measured absolute PKIKP arrival times. Also, PKIKP bottoming points and ray paths in the inner core are well distributed in the east-west and north-south hemispheres. We invert this dataset for two layer models of anisotropy in the inner core and compare the fits obtained with those predicted from the existing IMIC models. Our results show that, if there is an IMIC, its radius is most likely around similar to 500 km rather than the similar to 300 km originally proposed, and is in better agreement with the layering in the inner core based on PKIKP waveform modeling.