INTEGRATION THE NEW VELOCITIES RESULTS FROM MONITORING OF GEODYNAMIC PROCESSES IN THE AREA OF SOFIA IN THE COMMON FIELD OF HORIZONTAL VELOCITIES

Abstract

The monitoring of geodynamic processes with modern GNSS technology in the area of Sofia and Southwest Bulgaria has been going on for more than 25 years. To investigate modern crustal motions in the area, GNSS data obtained between 1996 and 2022 are analyzed to obtain the velocity field for southwestern Bulgaria. Every year, measurements are carried out on a part of the points, and the last measurements were carried out in 2022. For the entire period, monitoring covered 28 stations. To evaluate the new result for the obtained horizontal velocities of points from Sofia geodynamic network, they are combined with the results for the point velocities from EPN densification project and with the results from National GPS Network. Thus, the common field of horizontal velocities in the region can be determined. The three networks have reliable solutions for point coordinates and velocities. The combination of the three networks provides reliably determined velocities of more than 85 points in the relatively small region of southwestern Bulgaria. The high density of the points can be used for geodynamic study of the region. The results of the three networks supplement each other and are a base to evaluate the reliability of obtained velocities. From this point of view, the compliance and reliability are very high. The newly acquired velocities field confirms that the general tendency of movement of the points in the region of Southwest Bulgaria is in the south direction with respect to stable Eurasia, as a general tendency the velocities tend to increase from North to South. This pattern is in agreement with the extensive movement of southern Bulgaria and northern Greece. The obtained velocities field can be used for further detailed geodynamic and geological investigations of the fault structures in the region.