The Apparent Displacement Method as a Tool in Leveling Data Processing Applied for Validated Determination of Ground Deformation

Area of Inowrocław town is considered as tectonically active due to halotectonic movement of salt dipair situated there. The geodetic surveys carried out for the determination of terrain surface deformations over the years revealed characteristics of the movement. The evaluated vertical displacements based on measurements of benchmarks show different characteristics, depending on distant points assumed as reference benchmarks. This raises problems in analysis, interpretation of the results and decision makings in master planning. The authors demonstrate a method of adjustment calculations that minimize the inconsistencies between previously elaborated heights and inconsistencies of points considered as stabile benchmarks. Thanks to the new approach the point considered as reference were recognized as unstable. And for the others more consistent values of the displacements were obtained: several benchmarks demonstrated higher difference of displacement values in compare to the initial approach in adjustments ranging in the interval of –9 mm – +3 mm.