## 2 Materials and Methods
In order to discretize the created geometry, the element size, the element order, and the method was chosen as 4000 m, quadratic, and _patch conforming_, respectively.It is stated that discretizing the model into smaller elements will increase model accuracy [25], but this will increase the processing time and no solution may be obtained depending on the capacity of the computer. The 4000 m value was chosen here because the distance where the GNSS stations are closest to each other is approximately 4 km. There are two different options for element ordering in ANSYS software. These are linear and quadratic. Irregular shapes can be represented better with quadratic order. The surfaces of the geometry obtained in this study are not linear. Therefore, quadratic order was preferred. ANSYS software offers two methods for discretizing the model: patch conforming (bottom-up approach) or patch independent (top-down approach). These are the methods that specify how the mesh operation will be performed. In the patch-conforming method, the discretization process is carried out starting from the edges and moving towards the interior of the model. Thus, the boundaries of the model are preserved. The patch-independent method is vice versa, and the mesh process is performed from the inside to the outside of the model. After the mesh process, the elements and the nodes connecting them are formed. The value of the annual GNSS velocities at the nodes corresponding to the GNSS stations in the mesh network formed on the surface is defined as displacement. In total 18 GNSS station (Figure 6) velocities [42] have been defined as displacement in the software. The east, west, and north of the northern part of the MMF and the bottom surface of the entire 3D model have been selected as supports (Figure 8). The other GNSS station velocities that are in the study area have been used as test stations, and Root Mean Square Error (RMSE) values have been calculated through comparing GNSS and model velocities using Equation (10). This allows quantitative comparisons to be made between the model results. \[\text{RMSE}=\sqrt{\frac{\sum_{i=1}^{n}(v_{GNSS,i}-v_{model,i})^{2}}{n}} \tag{10}\]  
Here v\({}_{\text{GNSS}}\) and v\({}_{\text{model}}\) are the velocities of the GNSS stations and the model, respectively. There are many different meshing methods in ANSYS software. These are called _tetrahedron_, _hex dominant_, _sweep_, _mulizone_, _cartesian_, and _layered tetrahedron_. The element types used in the meshing are given in Figure 9. The methods use these elements. The _tetrahedron_ method uses only tetrahedron elements. In the _hex-dominant_ method, the hexahedron element is mainly used. It is recommended to use it in geometries that cannot be swept. In the _sweep_ method, if the object has a structure that can be swept, meshing is performed using hexahedron and prism elements. When this method is selected, it is also possible to define how the surfaces are meshed. When _quad/tri_ is selected, triangle and quadrilateral 2D elements are used together. In the _all tri_ and _all quad_ options, completely triangle and quadrilateral elements are used, respectively. In the _mulizone_ method,  
Figure 7: Created 3D geometry of the study area. discretization is performed according to the mapped mesh type selected. These options specify whether only hexahedron, or only prism, or both are used. In the software, they are named _hexa_, _prism_, and _hex/prism_, respectively. The _cartesian_ methods fits the geometry with an unstructured, relatively uniformly sized hexahedron element that is aligned to the given coordinate system. The _layered tetrahedra_ mesh approach fits the geometry through layering an unstructured tetrahedron element on a given layer height. Figure 8: Supports defined in ANSYS software. Figure 9: Mesh types (triangle and quadrilateral are 2D and the others are 3D).