This study includes two interdependent sections. The first section presents an analysis of Pn travel times to determine Pn velocity, Pn anisotropy and crustal thickness variations beneath Turkey and surroundings. Between 1999 and 2010, more than 50000 Pn arrivals are compiled from 700 regional earthquakes by 832 stations of permanent and temporary networks operated in the study area. A regularized least squares inversion method is used to estimate crustal thickness variations and image velocity perturbations in the uppermost mantle. The results reveal features that correlate well with the surface geology and the active tectonics of the region. In the second section of this book, shear wave splitting on records of core-refracted (SKS) phases are obtained. Waveform data from 850 teleseismic earthquakes occurred between 1999-2010 at epicentral distances greater than 84? and less than 130? with magnitudes greater than 6.0 are analyzed. A total number of 4163 splitting measurements are obtained from 217 broadband seismic stations located in and around Turkey. The anisotropy parameters measured from SKS are consistent with the results of similar studies.