## 1 Introduction
Its selection can be influenced by the tectonics and seismicity of the area, geology or terrain. The authors of [24] state that when combining networks based on multiple measurement techniques, the distances between individual measurement points should be close enough, but do not give a specific distance criterion. An analysis of vertical movements based on leveling data showed that such a criterion could be 10 km, while [25] stated that vertical movements of the Earth's crust are consistent within a radius of 40 km. The selection of such a distance should be based on detailed analyses at each selected location. In [26], based on SAR data, it was shown that crustal surface motions are not consistent even at a close ~100 m distance from a GNSS station. The analyses carried out in this work showed that even some IGS stations located in a tectonically and seismically stable area should not be accepted as adjustment points [5]. Studies [17] have shown that 100% of common points are not required for hybrid networks. Approximately 3% is sufficient but the only condition is the selection of the most relevant points in the network. \begin{table}
\begin{tabular}{p{108.4 pt} p{108.4 pt} p{108.4 pt} p{108.4 pt} p{108.4 pt} p{108.4 pt}} \hline \hline
**Leveling** & low time resolution & hard-to-find archive material & labor-intensive calculations and data preparation & no stable points of reference over time & relative measurement only \\ \hline
**GNSS** & low spatial resolution & no physical network structure & accuracy depends on the length of station operation & sensitivity to local geometrical effects or inherent movements & many variables affecting the result \\ \hline
**Hybrid network-velocity averaging** & sensitivity to outliers & additional analysis of variance required & statistical grouping and weighting of values & not very reliable accuracy & \\ \hline
**Hybrid network-adjustment** & sensitivity to incorrect input data & requires statistical assumptions & time required for data & determining observation weights & high dependence on network configuration and ’fixed’ points \\ \hline
**Hybrid network-transformation** & depends on the quality of input data & the need for even distribution of common points & non-modeling of non-linear deformations of the system & & \\ \hline
**Hybrid network-interpolation** & sensitivity to outliers & overfitting & value estimation & sensitivity to point location and density & edge effect \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Disadvantages of methods for modeling vertical movements of the Earth’s crust. \begin{table}
\begin{tabular}{p{108.4 pt} p{108.4 pt} p{108.4 pt} p{108.4 pt} p{108.4 pt}} \hline \hline
**Leveling** & high accuracy & direct measurement & error control & high measurement repeatability & high spatial resolution \\ \hline
**GNSS** & high time resolution & large spatial coverage & high availability of collections & & \\ \hline
**hybrid network-random errors** & reduction in the impact of random errors & one value representative for the area & & & \\ \hline
**velocity averaging** & elimination of random errors & data control, possibility of weighting observations & statistical evaluation of results & one consistent frame of reference & geometric network consistency check \\ \hline
**hybrid network-adjustment** & no need to import data into a single reference system beforehand & allows one to combine contemporary data & allows one to combine archival data with necessary spatial consistency & not very complicated preparation of input data & \\ \hline
**hybrid network-transformation** & completes values at any point of the phenomenon & enables continuous modeling of the phenomenon & enables the creation of numerical models & wide range of interpolation methods & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Advantages of methods for modeling vertical movements of the Earth’s crust.