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This product is a colour-coded velocity map of satellite radar point targets that shows velocity estimates for more than 14 million point targets in Hungary. The velocities were estimated from the motion history of each point that are based on an average of 100 independent satellite observations spread over around 6 years time span. The average velocity precision calculated from the displacement time series is below 0.5 mm/yr. For the creation of the map the Persistent Scatterer Synthetic Aperture Radar Interferometry (PSI) data processing method was applied on observations from October 2014 to January 2021 acquired by the Sentinel-1A and Sentinel-1B satellites of the European Union and European Space Agency Copernicus Programme in the descending orbit.
The colour-coded velocity map indicates relative stability with green, the increasing distance from the satellite - generally subsidence - is indicated with reddish whereas decreasing distance - generally uplift - with blueish colours. Due to the satellite observation geometry, vertical as well as horizontal motions also appear in the data, where the latter may be blue or red depending on the relative geometry. Over the size of the country, plate tectonic motions are also significant - see the inset of present-day three-dimensional crustal deformation from GPS observations. However, due to our processing strategy, the large-scale ongoing crustal deformation does not appear on this ground motion map, leaving smaller-scale natural and anthropogenic ground surface motions intact and more visible. The ground motion anomalies have mostly anthropogenic origins like water pumping, oil and gas extraction, mining activities etc. or motions, deformations of individual buildings or infrastructure elements. However, motions of natural origins like landslides, soil creep, erosion, compaction, swelling clay also appear. PSI point targets reflecting the satellite radar signals are generally buildings, parts of buildings, major infrastructure elements like bridges, dams, towers, railways, roads but also uncultivated, bare natural surfaces.