Monitoring the Kinematics of Anatolia Using Permanent GPS Network Stations

The establishment and promotion of three-dimensional geodetic networks supported by continuous Global Positioning System (GPS) data are capable of yielding valuable data in order to enable regional realisation of the International Terrestrial Reference Frame (ITRF) and monitor deformation of the lithosphere. Providing 24- hour continuous data in connection with International GPS Service (IGS) global stations, the Turkish Permanent GPS Network (TPGN) was established in 1999. The main goal of establishing these network stations is to provide adequate information on such an active area, where the collision between African, Arabian and Eurasian plates is occurring. An additional aim is continuous monitoring by TPGN and Marmara Region Continuous GPS Network (MAGNET) sites, for secular variations in the positions of the stations and for the abrupt changes in their positions associated with earthquakes, as were observed during and after the 17 August 1999 ‹zmit (Mw=7.4) event, to give information on the coseismic deformation field and on postseismic processes. At this preliminary stage in TPGN and MAGNET data analyses, horizontal velocity values have been obtained in the ITRF96 reference frame and have been used to constrain the interseismic velocity field in the region. This analysis includes 900 days beginning from the 230 th day of 1999 (18 August) (after the ‹zmit earthquake) until the end of 2001. In this paper, the TPGN is introduced to the Earth Science community. Its data analysis strategy and results from preliminary analysis of inter-seismic velocities of TPGN stations are also demonstrated and interpreted. Özet: Sürekli Küresel Konumlama Sistemi (GPS) verileri ile destekli üç boyutlu jeodezik alar›n kurulmas› ve gelifltirilmesi, Uluslararas› Yersel Referans Sistemi (ITRF) nin bölgesel olarak gerçeklefltirilmesi ve litosferdeki deformasyonun izlenmesi kapsam›nda deerli bir veri grubu salamaktad›r. Bu çal›flmalar›n ülkemizdeki uzant›s› olarak Uluslararas› GPS servisinin küresel noktalar› ile balant›l› her gün sürekli olarak 24 saat veri salayan Türkiye Sabit GPS ‹stasyonlar› (TPGN) 1999 y›l›nda kurulmufltur. Bu a¤›n kurulmas›ndaki temel hedef, Afrika, Arap ve Avrasya plakalar›n›n çarp›flt›¤› aktif bir alanda sürekli deformasyonlar› gözleyerek bölgenin kinematiini anlamakt›r. TPGN ve Marmara Bölgesi Sürekli GPS A¤› (MAGNET) istasyonlar› ile sürekli izleme faaliyetlerine ilave olarak, nokta konumlar›ndaki seküler deiflimlerin 17 Austos 1999 ‹zmit (Mw=7.4) depremi s›ras›nda ve sonras›ndaki kosismik deformasyon alan› ve postsismik sürece yönelik bilgilerin ortaya ç›kar›lmas›nda çal›fl›lm›flt›r. TPGN ve MAGNET verilerinin analizlerinde ilk aflamada ITRF 96 referans sisteminde yatay h›z deerleri hesaplanm›fl ve bunlar bölgenin intersismik h›z alan›n›n tan›mlanmas›nda kullan›lm›flt›r. Analizler, 1999 y›l›n›n 230'ncu (18 Austos) itibaren bafllat›lm›fl olup, ‹zmit depreminden sonra 2001 y›l›n›n sonuna kadar 900 günü kapsamaktad›r. Bu çal›flmada, Yer Bilimleri topluluuna TPGN tan›t›lmakta ve TPGN noktalar›n›n intersismik h›zlar›na yönelik yap›lan analizlerin ilk sonuçlar› verilerek yorumlanmaya çal›fl›lmaktad›r.