Numerous publications have confirmed the important contribution of applying GNSS satellite measurements in geologically unstable areas to the displacement measurements of engineering objects. Along with linking GNSS measurements of benchmarks considered to be stable in the long term to the nearest reference stations at appropriate measurement intervals. So, it was possible to improve the accuracy of measurements of vertical and horizontal coordinates in the area of Szczecin, ushering in coordinate errors of less than 2 and 5 mm. For objects of strategic use such as natural gas tanks located in salt formations, however, these values are too high. The displacement of salt formations is 0.5 mm per year. Therefore, I decided to review existing measurement methods in two areas with different geological structures - Szczecin and Wroclaw NW and SW Poland - as numerous spectrums of SAR methods. As a different method, I present the advantages of the radiometric method with the prospect of performing surveys in the abovementioned areas. The publication focuses on statistical analyses, and GNSS and radiometric field measurements are in progress.

This paper presents a study of vertical land movements conducted in northwestern Poland, covering the city of Szczecin. The land of Szczecin is made up of organic soils, covered in many places by water (lagoons, rivers, and lakes), which are susceptible to displacement; therefore, benchmarks in this area are susceptible to changes in height. The analysis of the geological structure of the near-surface layer of the Szczecin area, such as organic soils, sands, and clays, was carried out. The detailed recognition of geological structure in connection with height changes of benchmarks made it possible to locate stable benchmarks in the researched area. In the first step, the authors chose benchmarks in a stable geological structure based on archive data from the Polish Geodesy Documentation Center. In the second step, precise GNSS 3D measurements were performed in the direct vicinity of these benchmarks in order to verify their stability. Verified stations provided a reference for the reliable monitoring of the deformation of other surfaces resulting, for example, from changes in organic sediments. Existing and new engineering structures erected in the area of the Oder River Szczecin islands were selected for the final research of vertical land motions. Static GNSS observations were conducted in November 2020 and May 2021.