Teleseismic evidence for a break-off subducting slab under Eastern Turkey

We present seismic images of the upper mantle beneath Eastern Turkey determined by teleseismic tomography. The data are measured precisely from seismograms recoded by the Eastern Turkey Seismic Experiment network consisting of 29 portable stations and 2 permanent stations. Our results show that obvious high-velocity (high-V) anomalies of up to 2% are interrupted beneath Eastern Turkey, and subcrustal earthquakes occurred along these high-V anomalies. Pronounced low-velocity (low-V) anomalies are visible from the Arabian foreland basin in the southwest to the Caucasus region in the northeast, which extend down to about 400 km depth. These low-V anomalies are consistent with the existence of Late Cenozoic volcanism in the region. These results provide new constraints on the geodynamic processes in the east Anatolian plateau, suggesting that the break-off of the Arabian slab may play an important role in the formation of the Anatolian plateau and the volcanism in the region. These processes might be related to the collision of the Arabian plate with the Eurasian plate. (c) 2007 Elsevier B.V. All rights reserved.