Study on Ground Motions in Southwest Bulgaria based on in-Situ and Satellite Data

In the last decades data from satellites are being used more frequently to study the ground movements. This fact is evidenced by the increased number of research papers and projects using freely provided data by space agencies such ESA (European Space Agency) and JAXA (Japan Aerospace Exploration Agency) and increased revisiting time of the new instruments on-board satellites. Other reason for this increase are the latest developments in processing methods such as PSI (Persistent Scatterer Interferometry) and even increasing number of cloud processing options provided by universities and research centres. Nevertheless the information obtained by this manner has some drawbacks for example moderate spatial resolution. This is why in-situ data from precise GNSS (Global Navigation Satellite System) measurements are essential. In this study the authors used both kinds of data to study one of the regions of Bulgaria which is recognized to be highly prone to seismic and geological hazards namely the Southwest region. For this research two sources of data have been used – SAR (Synthetic Aperture Radar) data from Sentinel-1 mission of ESA and in-situ acquired contemporary and older GPS (Global Positioning System) data. As a result of SAR data processing produced were interferometric images from ascending and descending orbits to decrease the effect of the mountainous topography, while the results from the GNSS measurements were used for