Jeodezi

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Browsing Jeodezi by Subject "Faults(Geology) -- Turkey."

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    Analysis of total crustal deformation by the comparison of terrestrial and GPS measurement in the Marmara Region
    (Thesis (M.S.)-Bogazici University. Kandilli Observatory and Earthquake Research Institute, 2007., 2007.) Akay, Gözde.; Özener, Haluk.
    In order to monitor crustal movements along one of the branches of North Anatolian Fault Zone (NAFZ), Geodesy Department of Kandilli Observatory and Earthquake Research Institute (KOERI) established microgeodetic networks around the eastern Marmara Region. General Command of Mapping (GCM) - Istanbul Technical University (ITU) net as part of the networks was measured from 1941 to 2007 five times with both space methods and conventional methods. The terrestrial network implemented by GCM as constitution of nine pillars scattered around south and north of Iznik Mekece fault. The net was measured by trilateration and triangulation methods by GCM and ITU. After KOERI Geodesy Department joined GCMITU net in Marmara Microgeodetic Project, the net was also monitored by GPS Campaigns. This study is based on the use of repeated observations over the network and on the analysis of the results obtained from different epochs by means of displacements. Thus, first all epoch of observations were computed and then the amount of displacements were analyzed judging by the fault movement and the accuracy values for each observation method. In addition to this, in order to check the coherence of results, GPS campaign data have been processed in detail.
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    Determination of velocity field and strain accumulation of densification network in Marmara Region
    (Thesis (M.S.)-Bogazici University. Kandilli Observatory and Earthquake Research Institute, 2007., 2007.) Deniz, İlke.; Özener, Haluk.
    For the implementation of constructing continuously operating reference stations and determination of transformation parameters, Turkey has started a new project: Turkish Continuously Operating Reference Stations (CORS-TR). Network-120, Network-90, and Network-60 were created as CORS test networks. These networks were composed of 115 check points which were established by institutions such as Geodesy Department of Kandilli Observatory and Emihquake Research Institute of Bogazic;i University, Istanbul Metropolitan Municipality, General Command of Mapping (GCM), General Directorate of Land Registry and Cadastre, and TUB IT AK Marmara Research Center (MRC) in KIrklareli, Tekirdag, Bursa, Bilecik, and Adapazan. Before the 1999 earthquake, positions of 115 check points which are tied to Turkish National Fundamental GPS Network (TNFGN) were determined by different time and institutions. Between July 15 and October 30, 2006; corporations such as TOPCON, TRIMBLE, and LEICA made observations. They evaluated CORS test networks. TOPCON and TRIMBLE measured all of CORS test networks, but LEICA measured only Network-60. Positions of main points of test networks were calculated and points were tied to International GNSS Service (lGS). The purpose of this study is to provide analysis of datum of 1999 observations and unity of datum, to analyze evaluation and computation of coordinates of 2006 observations, and to examine unity of datum in 2006 observations. It will also describe the determination of velocity field, strain accumulation on test field by modeling difference vectors between the coordinates of check points and the comparisons with other studies. The difference vector between the coordinates of check points in 1999 and 2006 (observed and computed by different companies) were derived.
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    Earthquake potential of the East Anatolian Fault
    (Thesis (M.S.) - Bogazici University. Kandilli Observatory and Earthquake Research Institute, 2020., 2020.) Uçan, Kaan Alper.; Bulut, Fatih.
    This study aims to forecast magnitude of future strong (6.0 M <7.0) and major (7.0 M <8.0) earthquakes along the East Anatolian Fault Zone (EAFZ hereafter), which is a seismically active plate boundary between Arabian and Anatolian plates. In this context, we investigated segmentation of the EAFZ reviewing previous studies on structural variation zone and historical earthquakes. We analysed the combined GPS velocity eld to obtain back-slips using steepest descent/gradient inversion method. The method projects GPS-derived back-slip rates onto the fault plane using Okada's quasi-in nite space model simulating elastic Green's functions to obtain on-fault slip de cit rates. Resulting slip de cit rates are used to estimate present-day slip budgets on each fault segment. We also analysed along-fault b-value distribution to verify if it can be used to di erentiate between locked and creeping patches. Our results show that the EAFZ currently have a 1.51 m average slip. We suggest that the EAFZ is split into eight fault segments generating strong/major earthquakes. The January 24, 2020 Elaz g earthquake (M 6.8) ruptured the Sivrice-Pütürge segment verifying our segmentation model and magnitude forecasts for future earthquakes. We found no slip de cit accumulation observed on the Hacılar segment. Remaining six segments are able to generate three strong, three major earthquakes. Currently Karlıova, Kaleönü-Beyhan, Palu-Sivrice, Taştepe, Çelikhan-Erkenek, Gölbaşı-Pazarcık segments can currently generate M 7.0, M 6.9, M 7.1, M 6.8, M 6.9, M 7.4 earthquakes, respectively. Karlıova, Palu-Sivrice, Taştepe, Gölbaşı-Pazarcık segments currently have the potential to generate previous strong/major earthquakes they hosted. We observed a reverse correlation between slip de cit rates and b-values verifying that b-value can be used to discriminate locked and creeping fault segments.
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    Installation of borehole strainmeters to monitor North Anatolian fault near Istanbul
    (Thesis (M.S.) - Bogazici University. Kandilli Observatory and Earthquake Research Institute, 2018., 2018.) Bal, Osman.; Özener, Haluk.
    The North Anatolian Fault Zone (NAFZ) , which forms the plate boundary between the Anatolian plate in the south and the Eurasian plate in the north, runs under the Marmara Sea and is located less than 20 km from the city of _Istanbul. According to historical seismicity data and recurrence times; an earthquake, which is bigger than magnitude 7, is expected. Geodesists have been doing many observations on the NAFZ with various techniques since 1972. Geodesy Department of Kandilli Observatory and Earthquake Research Institute (KOERI) plays a crucial role on deformation measurement on the NAFZ with its micro-geodetic networks since 1989. By using the developing technology in time, Geodesy Department of KOERI incorporated some other terrestrial deformation measuring techniques like creepmeters and strainmeters. The aim of this thesis is to discuss, the need of the strainmeter, installation cases for two boreholes, solutions found for site speci c problems and the result of installation. Installed strainmeters will allow us to monitor potential slow-slip events along the Marmara Seismic Gap.
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    Seismo-geodetic characterization of the Tuzla Fault (İzmir/Turkey) : |its kinematics and earthquake potential
    (Thesis (M.S.) - Bogazici University. Kandilli Observatory and Earthquake Research Institute, 2020., 2020.) Gelin, Bengisu.; Bulut, Fatih.
    Izmir, the third largest city of Turkey, located in western coast of the country is seismically super active due to Hellenic subduction zone and extensional back-arc basin under the Aegean Sea. This tectonic environment has attened the cities in the region again and again as reported in the historical records. Hence, investigating the seismically active faults in the region is crucial to elaborate on earthquake hazard for the cities along the Western Turkey. In this context, we jointly analyzed geodetic, geological and seismological data to investigate latest failure, present day deformation, slip accumulation and fault kinematics along the Tuzla Fault. Historical and recent earthquakes were investigated to determine the latest failure of the Fault and result reveals that there is no evidence of a large earthquake failing the Fault entirely since 1688. Six epochs GPS measurements of fteen stations were analyzed for the time period of 2009-2017 to obtain horizontal tectonic slip rates along the Tuzla Fault. As a result, overall southwest movements change between 26.67 1.03 mm/yr and 28.96 1.00 mm/yr with respect to Eurasia. Di erential slip rates range between 1.00 to 2.00 mm/yr. Magnitude calculations were done for Tuzla Fault and its segments seperately. Tuzla Fault has currently a potential to generate a strong earthquake up to M6.2-M6.8. Strain analysis results show that the Çatalca Segment and northern Orhanlı Segment, accumulates high shear strain and therefore accommodate higher potential for co-seismic slip. According to fault plane solutions and maximum shear strain values and planes, Cumalı Segment has dextral characteristic, however, maximum shear strain planes indicates sinistral structure in Çatalca Segment.
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    Time series analysis of GPS permanent stations around east Anatolia
    (Thesis (M.S.) - Bogazici University. Kandilli Observatory and Earthquake Research Institute, 2016., 2016.) Julaiti, Wumiti.; Ergintav, Semih.
    The eastern part of Anatolia is a significant location in the world due to its tectonically active background. It includes one of the major fault zone of Anatolia: left-lateral East Anatolian Fault (EAF), forming a boundary between the Anatolian and the Arabian plates. Its long-term slip rate as well as localizations of creeping zones, locking depth and the surface offsets can be obtained by using inter-seismic Global Positioning system (GPS) velocities and proper models. However, the quality of position time series generated from each GPS station directly determines the accuracy of the velocity estimation. The Continuous Operating Reference Stations (CORS) of Turkish National Permanent GNSS Network-Active (TNPGN-Active), mainly using the GPS measurements, covers the most area of Turkey, including the whole segments of the EAF. In the thesis duration, a limited part of the TNPGN-Active data could be archived. Then, as a thesis objective, we decided to control the quality of GPS velocities, estimated from limited data of stations around the EAF, in order to improve the GPS velocity field in this region. In this study, 2-year span GPS data from 37 sites of TNPGN-Active were processed by using GAMIT/GLOBK to generate daily position time series of each station as well as the related velocity estimates. For the GPS time series, mainly noise analysis was applied to distinguish which station is sufficient enough for using its velocity estimates. Finally, it has been found that the velocity estimates of at least three specific stations with spectral indices > 0.7 and linear trend uncertainties > 2.5 mm on horizontal components, which are MUUS, HINI and GEME, are not quite reliable with the limited 2-year data. This result will be highly likely an important reference for the campaign type GPS study along Hazar-Palu segment of the EAF in the future. To estimate a high quality velocity field, new campaign sites could be added around the problematic TNPGN-Active stations.