## 1 Introduction  
Three main pressure types have been applied to describe subsurface pressure conditions: the hydrostatic, the pore, and the lithostatic pressure. The hydrostatic pressure is the pressure of the water column, while the lithostatic is the pressure of the overburden rock mass at a given depth. Finally, the pore pressure means a pressure value that is measurable in the pore fluids. The hydrostatic pressure regime is present when the pore pressure is equal with the hydrostatic pressure. An abnormal pressure regime occurs when the pore pressure is smaller or higher than the hydrostatic pressure. Underpressure is the condition when the pore pressure is lower the hydrostatic; this is the less frequent situation. However, overpressure is present when the pore pressure exceeds the hydrostatic conditions; it is known from several young sedimentary basins [1, 2, 3, 4, 5, 6]. The overpressure generation mechanisms have been divided into three groups in case of sedimentary basins. The first group is triggered by the increase of compressive stress, which inherits the disequilibrium compaction and the tectonic stress generated overpressure. The disequilibrium compaction or under-compaction is the process when a huge amount of shale-rich sediments has been deposited within a short period. The compaction of the sediments is not able to follow the fast burial, so the pore fluid will be captured in the pore space, which increases the pore pressure, this mechanism is frequent in case of Cenozoic basins with a high sedimentation rate [7]. Volume of the pore fluid can be increased that is able to generate abnormal pressure conditions, the volume expansion mainly has been controlled by aquathermal and diagenetic processes, hydrocarbon generation, or cracking. The third mechanism group has been resulted by the fluid and pressure allocation, due to the osmosis, hydraulic head, buoyancy, and lateral transfer [8; 9]. The overpressure difference between the deep basins and the basin margin could be smoothed by the hydraulic linkage of connected tilted reservoirs, which can result a higher pore pressure on the basin margins than could be expected based on the overlaying shales. The different overpressure generation mechanisms simultaneously make an impact on the subsurface pressure regime, so the understanding of the mechanisms is necessary for planning and carrying out successful hydrocarbon exploration wells. Two main explanation groups have been developed to explain the abnormal pressure regime in case of the Pannonian Basin. According to the first explanation, the overpressure has been generated by the hydrocarbon generation; the disequilibrium compaction and the chemical compaction may affect the pressure conditions, but the last mechanism has not been investigated [10]. However, the second group explains the overpressure generation with the increase of the tectonic stress that is originated from the subduction of microplates [11; 12]. Previous studies have not dealt with the individual quantitative contribution of the overpressure generation mechanisms to the whole subsurface regime. The aim of this study was not only identifying the generation mechanisms but delivering information about the individual contribution of them; thus, 2D basin models have been developed to evaluate the magnitude of the different mechanisms. The applied workflow has been improved that resulted in a stochastic numerical simulation workflow to pore pressure prediction. The test area is selected in the Danube-Tisza Interfluve, which is located in Hungary, East-Europe (Figure 1). Figure 1: Topographic map of the Pannonian (modified after [13]) basin with the main subbasins; the yellow outline represents the political border of Hungary, and the red lines show the direction of the Section_01 (from NW to SE) and Section_01A (from NE to SW). The map uses EOV (Uniform National Projection system), which is a plane projection system  
used uniformly for the Hungarian civilian base maps and spatial informatics.