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Height differences from geometric leveling, gravity and GPS measurements carried out from 1979 until now in the network of Volvi area are systematically analyzed. Various methods and algorithmic techniques based on integrated approach are rigorously applied in order to extract a more reliable estimation of the vertical components of the deformation field. Signals, i.e. the gravity field parameters, their variations in time and the vertical displacements are treated in a combined analytical-stochastic approach. Finally the interpretation of the results at the interesting area of the Volvi Lake is attempted. The estimation of displacement and especially the height differences at Volvi area is very important in Greece due to its seismic activity. Volvi area is located at northern Greece (Central Macedonia) and 40Km from the city of Thessaloniki. Volvi take up an area of 10X15km including two lakes (Lagada and Volvi) and is considered as a geodynamically interesting area. The largest earth ...
Height differences from geometric leveling, gravity and GPS measurements carried out from 1979 until now in the network of Volvi area are systematically analyzed. Various methods and algorithmic techniques based on integrated approach are rigorously applied in order to extract a more reliable estimation of the vertical components of the deformation field. Signals, i.e. the gravity field parameters, their variations in time and the vertical displacements are treated in a combined analytical-stochastic approach. Finally the interpretation of the results at the interesting area of the Volvi Lake is attempted. The estimation of displacement and especially the height differences at Volvi area is very important in Greece due to its seismic activity. Volvi area is located at northern Greece (Central Macedonia) and 40Km from the city of Thessaloniki. Volvi take up an area of 10X15km including two lakes (Lagada and Volvi) and is considered as a geodynamically interesting area. The largest earthquake took place in May 23, 1978 (Ms= 5.8), June 19, 1978 (Ms= 5.2) and June, 20 1978 (Ms= 6.2) followed by a series of postseismic activity affected socially and financially the city of Thessaloniki. In order to study the geodynamical behaviour and investigate the crustal movements a geodetic and gravimetric network was established with 16 and 26 pillars respectively. Classical measurements are available for the epoch 1979, gravity measurements took place in 1979 and 1999 while GPS measurements performed in 1994, 1995, 1996 and 2003. Integrated geodesy in time deals with the analysis of the above observations for the study of network geometry and its variation with time, when these observations depend on the gravity field of the earth and its temporal variation. Integrated adjustment has been introduced as a rigorous adjustment of observations with both geometric and gravimetric information using precise mathematical goals. Furthermore, integrated geodesy is a method for the adjustment of observations depending not only on discrete parameters but also on unknown functions. Parameters appearing in the mathematical model can be treated as: a) deterministic b) stochastic c) analytical - stochastic way and these leads to an adjustment with signals. Geodetic-gravimetric network deals with GPS baselines, leveling and gravity observations in different epochs so orthometric heights are much easier to calculate. The object of the present dissertation is the simultaneously analysis of GPS baselines with classical geodetic observations (angles and height differences) and physical data related to the gravity field (deviations of the vertical, intensity of gravity field) and/or seismological data (geophysical model, P waves) with models of integrated geodesy, having as main purpose the estimation of orthometric heights. In the first chapter informations are given about the reference frames and the relationships between them. An extensive reference is made to concepts and definitions in relation with heights. In the second chapter modelling alternatives in deformation measurements are given. In the third chapter the linearized observation equations are analyzed for the global positioning system GPS, height differences, gravity and seismic waves. In the fourth chapter analytical and stochastic models are presented for vertical movements. Moreover, in the fifth chapter the covariance of the gravity field is given and the models of the covariance functions are presented (exponential, Reilly, Moritz, Poisson). In the six chapter the height differences in Volvi area is presented. Signals s take for granted that are unchangeably from 1994 unit 2003 but gravity measurements which took place in 1979 and 1999 are changed since points are moved. That simplifies the mathematical model and makes calculations easier. In the end, we will define integrated geodesy as a powerful mathematical tool which manipulates physical and geometrical observations measured in different epochs making signal connection by the covariance gravity model. Height differences calculated with high accuracy. Also, the biggest height differences occurred near to points which indicate the epicentre of the earthquakes. In the seven chapter conclusions are given coming from different solutions.
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