Monday 22 August 2005

G4

PM0024
Establishment of regional reference frames for detecting active deformation areas in Anatolia
Aktug, Bahadir¹, Kilicoglu, Ali¹
1 General Command Of Mapping, Turkey
Author email: baktug@hgk.mil.tr
GPS studies in Turkey date back to early 1990s. More than 80 GPS surveys have been carried out across Turkey since 1992. In addition to this temporal resolution, a spatial resolution of 30-50 km inter-station distance was achieved upon completion of Turkish National Fundamental GPS Network (TNFGN) in 1999. Besides, permanent GPS network is still in progress and currently 15 permanent sites are operational. TNFGN, consisting of sites in Eurasian, Anatolian and Arabian plates with relatively high spatial resolution needs specific frame realizations in order to expose areas of active deformation and to sustain the spatial and temporal consistency of coordinates and velocities of neighboring sites. Global or regional sites to be used in frame realizations were carefully selected through IGS time series and regional strain analysis. We compute velocity fields in various frames at about 400 sites in Turkey from GPS measurements between the years 1992 and 2004. Each frame realization can be considered as revealing or substantiating different geophysical phenomena; a Eurasia-fixed frame quantifying rigid-body rotation of Central Anatolia and dextral North Anatolia mega shear zone, an Arabia-fixed frame constraining the East Anatolian thrust and sinistral shear zone, an Anatolia-fixed frame putting an upper bound to the extension of West Anatolia and rigidity of Central Anatolia. We derive a best fitting Euler vector of Anatolia-Eurasia motion 31.7 ± 0.1N, 31.8 ± 0.1E, 1.45 ± 0.01 deg/Myr using sites in rigid part of Anatolia. The Euler vector gives about 25 mm/yr for an upper bound of NAF slip. Relative motion of Arabian Plate to the Anatolia was found to be 33.8 ± 0.2N, 38.4 ± 0.1E, 0.97 ± 0.04 deg/Myr. Central and Eastern Anatolia are characterized as being in coherent and diffused deformation respectively, while Anatolian plate decouples from Arabian plate along sinistral East Anatolian Fault (EAF).

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