Moho depth and VP/VS variations in the Kope Dagh region from analysis of teleseismic receiver functions



In this study we use the P receiver function technique to determine the Moho depth and Vp/Vs ratio for 8 short period stations of Qochan and Mashhad seismic networks and map the variations of Moho depth under Kope Dagh region. It is shown that a receiver function can provide a relatively good point measurement of Moho depth under a short period station. The crustal thickness estimated from the delay time of the Moho P-to-S converted phase trades off strongly with the crustal Vp/Vs ratio. The ambiguity can be reduced significantly by incorporating the later multiple converted phases, namely, the PpPs and PpSs+PsPs. We use a stacking algorithm which sums the amplitudes of receiver function at the predicted arrival times of these phases by different crustal thicknesses H and Vp/Vs ratios (zhu & kanamori,2000). This transforms the time domain receiver functions directly into the H-Vp/Vs domain without need to identify these phases and to pick their arrival times. The best estimations of crustal thickness and Vp/Vs ratio are found when the three phases are stacked coherently. Applying this technique to 8 stations in Kope Dagh region reveals that the Moho depth is approximately 45 km on average and varies between 41 and 49 km. Thick and thin crust are found under the southern and northern Rang, respectively. These results are in good agreement with the geology and tectonic setting of this region.