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    時間:2019-08-23 來源:未知 點擊:
    報告題目:Tectonic morphological deformation of İzmit Bay, Turkey and its spatio-temporal monitoring by seismo-geodetic networks and InSAR techniques
    報  告  人:Aydın Üstün, PhD,Kocaeli University  
    邀  請  人:方  興 副教授   
    He was born in 1971 in Milas, Turkey and graduated from Selçuk University Geodesy and Photogrammetry Engineering in 1993. He had his MSc and PhD degrees on mathematical and physical geodesy at the Graduate School of Natural and Applied Science at Yıldız Technical University, İstanbul in 1996 and 2002, respectively. Between 2003 and 2014, he studied in the department of geomatics engineering at Selçuk University as professor and the head of geodesy division. He was awarded by the post-doctoral research fellowships of TÜBİTAK and the Council of Higher Education of Turkey in Leibniz University Hannover and Florida Atlantic University. Since 2014, he has been working in the Geomatics Engineering Department in Kocaeli. In addition to teaching and research responsibilities, he is also the head of the department. His research fields cover mathematical and physical geodesy and space geodetic techniques. He has conducted and participated into the TÜBITAK and EU funded research projects focusing on gravity field recovery using low earth orbiters, geoid determination and surface deformations in basin scales based on geodetic and geotechnical methods.
    The tectonic geomorphological evolution of Izmit Bay has been mainly driven by North Anatolian Fault Zone (NAFZ) and the fallowing transportation of alluvial sediments from the surrounding slopes thanks to rivers and streams. Both physical phenomena have shaped the present geomorphology in İzmit Bay during the Cenozoic time era. Today, another dynamic, i.e. the anthropogenic impact has played an extra role over the basin by changing environmental conditions because of increasing building demand and urbanization policy of city planners and decision makers. In this study, starting from the İzmit Earthquake, Mw = 7.4 on 17 August, 1999, surface displacements have been mapped and reanalyzed by space geodetic techniques such as GNSS and multi-band InSAR techniques. In the Marmara region, today, ongoing research projects are interested in modeling current kinematics of the NAFZ with the aim of predicting potential consequences of the expected İstanbul earthquake. In this study we deal with subsidence and ground stability conditions in coastal areas where the building density has showed faster growth trend for the last 2 decades. A research project that addresses these problems has been introduced and the results of recent surface displacements are discussed for better understanding of surface dynamics in İzmit Bay. A control survey to state horizontal and vertical deformation pattern of 8 years in İzmit Bay is given. According to the results, the varying displacement values (max. 33 cm) have shown a significant vertical deformation along the shorelines and recreated filling areas along Izmit Bay. And also, a research based on the multiband InSAR interferograms between 2014-2018 confirms these subsidence occurrences and its extent over the basin. It is pointed out that the liquefaction effects on the river beds and deltas in coastal zones have caused unstable ground conditions that mean subsidence throughout the shorelines with low topography. In addition, for long term monitoring purposes, the current status of the establishment of seismo-geodetic network that enables high rate tracking of 1 – 100 Hz in case of strong ground movements and some examples of these preliminary studies have been presented.