The East Anatolian High Plateau is a region of average ∼2 km elevation a.s.l. exhibiting active diffuse N‐S shortening and widespread Pliocene to recent volcanicity. Its elevation was hitherto thought to result from a presumed crustal thickness of ±55 km. Seismic data collected by a new network of 29 seismograph stations have shown, however, that its crustal thickness is only some 45 km. Combined with observations on Pn and Sn phases, this shows that most of the East Anatolian High Plateau is devoid of mantle lithosphere. Areas of no mantle lithosphere are inferred to coincide broadly with the extent of the East Anatolian Accretionary Complex, a subduction‐accretion prism of late Cretaceous to earliest Oligocene age. The absence of mantle lithosphere is ascribed to breakoff of northward subducted slab beneath the prism and the widespread vulcanicity to melting its lower levels because of direct contact with hot astenosphere. The East Anatolian High Plateau is thus supported not by thick crust, but by hot mantle.

The crustal structure of the Anatolian plateau in Eastern Turkey is investigated using receiver functions obtained from the teleseismic recordings of a 29 broadband PASSCAL temporary network, i.e., the Eastern Turkey Seismic Experiment [ETSE]. The S‐wave velocity structure was estimated from the stacked receiver functions by performing a 6‐plane layered grid search scheme in order to model the first order features in the receiver functions with minimum trade‐off. We found no significant crustal root beneath the western portion of the network, but there is some evidence of crustal thickening in the northern portion of the network. We found an average crustal thickness of 45 km and an average crustal shear velocity of 3.7 km/s for the entire eastern Anatolian plateau. Within the Anatolian plateau we found evidence of a prominent low velocity zone where the crust thickness is approximately 46 km. These results suggests that the 2 km high topography across the Anatolian plateau is dynamically supported because most of the plateau appears to be isostatically under‐compensated. Also, there appears to be a region of thin crust at the easternmost edge of the Anatolian plateau that may be a relic from the accretion of island arcs to the Eurasian plate.

SUMMARY Teleseismic phase readings from the Eastern Turkey Seismic Experiment (ETSE) have been inverted using teleseismic tomography in order to create a 3‐D image of the underlying mantle beneath Eastern Turkey. The aim was to investigate the existence of an upper mantle negative velocity anomaly that is used to explain the uplift of Eastern Anatolian plateau and the potential pieces of detached oceanic slabs related to Neo‐Tethyan subduction suggested by previous studies. Using teleseismic waveforms from the 29 stations of the Eastern Turkey Seismic Experiment, 2926 direct P phases from 146 events were picked by using adaptive stacking techniques. In order to increase the station coverage and resolve the surrounding area, the phase readings from the International Seismological Center (ISC) Bulletin have also been added. The data set consists of 9571 P and PKP phase readings of 79 stations from 503 teleseismic events. This study develops the first high‐resolution 3‐D upper mantle P‐wave tomographic model for this region. The tomographic results show the existence of an upper mantle negative velocity anomaly to a depth of ∼200 km beneath the eastern Anatolian accreationary complex (EAAC) as commonly observed in the previous studies that suggest a shallow partially molten asthenosphere. The slab‐like high velocity anomalies beneath the EAAC, Pontides and Caucasus are interpreted as the detached southern and northern Neo‐Tethys slabs.

We have determined the shear wave splitting fast polarization direction and delay time using data from the ETSE broadband experiment (Eastern Turkey Seismic Experiment), a deployment of 29 broadband seismic stations across the collision zone of the Arabian, Eurasian, and Anatolian plates. Our results show that the fast polarization directions are relatively uniform and they exhibit primarily NE–SW orientations. No abrupt changes in anisotropy directions are observed across the main tectonic units in the region: the Bitlis Suture (BS) and the North and Eastern Anatolian Fault zones. The fast polarization directions are determined to be sub‐parallel to the Anatolian, Arabian, and Eurasian absolute plate velocities, except for those stations in the northeastern corner of the Anatolian Plateau. Observed delay times range from 0.7 to 2.0 seconds with an average value of 1.0 second; the largest values are within the northern Anatolian Plateau which is underlain by an exceptionally low velocity zone in the uppermost mantle. We interpret shear wave splitting as the vector difference of the Eurasian lithosphere and northeastern or southwestern directed flow of the asthenospheric mantle. Comparisons of the polarization anisotropy with measurements of Pn azimuthal anisotropy suggest vertical anisotropic layering except in those areas which are underlain by partially molten uppermost mantle.