The monitoring of gravity changes in a region enables the investigation of regional structural elements depending upon the changes in load compensation. This method, preferred in recent years, has yielded good results from different parts of the world for determination of the deformation at fields. With the addition of GPS/GNSS monitoring to microgravity studies, the mass changes within the crust in vertical directional movements of a region can be estimated. During GPS/GNSS monitoring and microgravity studies, it was found that the behaviour of vertical directions of Izmir and the surrounding areas, indicate an active tectonic regime and high seismic activity, especially since 2000. As a result, regions considered to have a mass change in vertical direction were determined by 3-year measurements and it was found that they were consistently highly seismic.

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The Western Anatolia and the Aegean Sea regions are one of the most significant seismically active and rapidly deforming fields in the world. Generally, seismic activities cause deformations and these deformations are monitored with Global Positioning System (GPS) / Global Navigation System (GNSS). In this context, GPS data were used to determine the deformation of İzmir and its surrounding to estimate the relative plate motions. In this study, the kinematic structures of the faults, which control the seismic hazard in İzmir and its surroundings, processing results of the three-year (2009, 2010 and 2011) episodic GPS observations and the estimation of displacements for 21 GPS stations were presented. The aim of this study is to examine interplate motion of the stations and their relations with the tectonic structures, seismicity and paleomagnetism and additionally, to interprete the motions of the study area relative to different block motions. Consequently, the mean motion of the study area was found approximately 25 mm/yr (towards the SSW) in the Eurasia fixed frame solution. The Aegean block fixed frame and the Anatolian block fixed frame solutions were computed relative to Euler vectors. In Aegean and Anatolian block solutions it was determined that the stations move separately, not as a group. In Euler pole solution, some stations are separated from each other and meanwhile some stations are grouped by considering the differences and similarities of the station motions. According to this solution three lines and two regions were described in the study area. The relations between seismicity and paleomagnetic studies and the kinematic structures determined in Anatolian block fixed frame and Euler pole solution were also investigated. When the Anatolian block fixed frame

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The tectonic regime of Eastern Anatolia is determined by Arabian-Eurasian continentcontinent convergence and the mechanism occurred with the convergence. North Anatolian Fault Zone (NAFZ), Eastern Anatolian Fault Zone (EAFZ), North Eastern Anatolian Faults and Bitlis Zagros Suture Zone are formed by this convergence, represent the characteristic of lithospheric structure of the region. In the scope of this study, the gravity anomalies of Eastern Anatolia were used for investigating the lithospheric structure. Firstly, second order trend analyses were applied to gravity data for examining the characteristic of the anomaly. Later, the vertical and horizontal derivatives methods were applied to the same data. Generally, the purpose of the applying derivative methods is determining the vertical and horizontal borders of the structure. Therefore, this method gives the opinion about the characteristic of the lithospheric structure of the study region. According to the results of derivative methods, the structure transitions were increased rather especially with Bitlis Zagros Suture Zone. At the last step, the gravity studies were evaluated together with the seismic activity of the region. Consequently, the geodynamical structure of the region is examined with the previous studies done in the region.