The crustal structure of the East Anatolian plateau (Turkey) from receiver functions

An edited version of this paper was published by the American Geophysical Union (AGU). Copyright 2003, AGU. See also: http://www.agu.org/pubs/crossref/2003.../2003GL018192.shtml; http://atlas.geo.cornell.edu/turkey/publications/Zor-et-al_2003.htmThe 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

Seismic investigation of the crustal structure in central Anatolia.

Ph.D. - Doctoral Progra

Detection and Classification of Volcanic Earthquakes/Tremors in Central Anatolian Volcanic Province

Central Anatolia has been characterized by active volcanism since ∼10 Ma which created the so called CentralAnatolia Volcanic Province (CAVP) where a series of volcanoes are located along the NE-SW trend. Thepetrological investigations reveal that the magma source in the CAVP has both subduction and asthenosphericsignature possibly due to tearing of ongoing northward subduction of African plate along Aegean and Cyprusarcs. Recently, a temporary seismic array was deployed within the scope of Continental Dynamics: CentralAnatolian Tectonics (CD-CAT) project and provided a unique opportunity to study the deep seismic signature ofthe CAVP. Passive seismic imaging efforts and magnetotellurics (MT) observations revealed low velocity and highconductivity zones supporting the presence of localized partial melt bodies beneath the CAVP at varying depths,especially around Mt. Hasan which exhibits both geological and archeological evidences for its eruption around7500 B.C. In Central Anatolia, local seismicity detected by the CD-CAT array coincides well with the activefaults zones. However, active or potentially active volcanoes within CAVP are characterized by the lack of seismicactivity. In this study, seismic data recorded by permanent stations of Regional Earthquake-Tsunami MonitoringCenter were combined with temporary seismic data collected by the CD-CAT array to improve sampling densityacross the CAVP. Later, the continuous seismic waveforms of randomly selected time intervals were manuallyanalyzed to identify initially undetected seismic sources which have signal characters matching to volcanicearthquakes/tremors. For candidate events, frequency spectrums are constructed to classify the sources accordingto their physical mechanisms. Preliminary results support the presence of both volcano-tectonic (VT) and low-period (LT) events within the CAVP. In the next stage, the spectral and polarization analyses techniques will beutilized to the entire seismic database to detect and classify the seismic source associated to volcanism, and iden-tified events will be relocated and jointly interpreted with subsurface features detected by seismic imaging and MT

Contribution to the seismotectonics of eastern Turkey from moderate and small size events

An edited version of this paper was published by the American Geophysical Union (AGU). Copyright 2003, AGU. See also: http://www.agu.org/pubs/crossref/2003.../2003GL018258.shtml; http://atlas.geo.cornell.edu/turkey/publications/Orgulu-et-al_2003.htmSource properties of small-to-moderate magnitude events in eastern Turkey were studied using high quality waveform data produced by the Eastern Turkey Seismic Experiment (ETSE). A data set of fault plane solutions was obtained for 134 earthquakes using the regional moment tensor inversion technique for 34 events with magnitude 3.7 and above, and first motion analysis for 115 earthquakes with magnitude 3.0 and higher (for 15 events both techniques were used). Most of the events studied had strike slip mechanisms in agreement with nearby local fault structures. Reverse mechanisms were more scarce and were restricted to certain areas, such as in the eastern Anatolian plateau and southwest of the Karliova junction along the Arabian plate boundary. Our results indicate a difference in the deformational style east and west of the Karliova junction which results in internal deformation in the east and westward extrusion of the Anatolian plate with no or very little internal deformation in the west. Our results also suggest that in eastern Turkey, most of the collision is taken up by strike slip faults of varying types and sizes, suggesting that the northward convergence of Arabia is being accommodated by escape tectonics. Compressive features, such as thrust faulting, which were obviously the primary faulting during the earliest stages of continental collision, are still active but are of lesser importance

The effects of subduction termination on the continental lithosphere: Linking volcanism, deformation, surface uplift, and slab tearing in central Anatolia

Subduction beneath central Anatolia represents the transition between continuous subduction along the Aegean trench in the west and slab break-off and/or subduction termination at the Arabian-Eurasian collision zone in the east. Using recently collected seismic data from the Continental Dynamics-Central Anatolian Tectonics project alongside a newly developed approach to the creation of a 3D shear-velocity model from the joint inversion of receiver functions and surface-wave dispersion data, we can gain important insights into the character of the downgoing, segmenting African lithosphere and its relationship with the overriding Central Anatolian plate