Estimating vertical movement of the earth’s crust in Lithuania using different methods

Abstract

The levelling network is arranged in separate lines that together form levelling polygons. When determining the vertical movements of the Earth’s surface based on the results of levelling measurements, the results are obtained only at the location of the geodetic network. During the compilation of the vertical movements of the Earth’s surface, a significant part of the studied area lacks measurement-based results, and the movement values are obtained by interpolation. Therefore, measurements of movement obtained inside levelling polygons are relatively inaccurate, and active centres of movement are concentrated only on the levelling lines. The present article introduces a methodology that allows determining the vertical surface movements in the entire area. The methodology holistically employs statistical methods, geoindexes, and levelling measurement data. Movement values are calculated for points evenly spaced throughout the entire area. The vertical movement map compiled based on this methodology is not subject to such significant influence by the interpretations of the interpolation algorithm, moreover, it avoids the concentration of movements in the levelling lines. During the study, three maps of vertical movements of the Earth’s surface are compiled: one is created on the basis of the levelling results, and two other maps — using the proposed methodology. The comparison of the maps reveals that the main rising/sinking tendencies of the Earth’s surface match, and simultaneously the concentration of movements in geodetic points is avoided.