## 4 Results
### Correlation Between Pore Pressure and GWL Evolution  
We monitored the pore pressure evolving at several selected locations in the model. The locations correspond to the groundwater monitoring wells that are shown in Figure 2.  
The pore pressure evolution simulated at location Well 5 is presented in Figure 10. The Well 5 location correspond to the GWL monitoring station 5, Gyeong-Ju San-Nae. The modeled pore pressure curve is characterized by high-frequency fluctuation (Figure 10a), whereas the GWL changes were monitored at 1-day intervals (Figure 10b). The red arrow indicates the time of the GJEQ occurrence, which was at 256 days elapsed since 1 January 2016. The pore pressure exhibits an instantaneous and sharp rise at the moment of the earthquake, representing the rapid stress transfer caused by the fault rupture. After this abrupt increase, the pressure undergoes a slow decay phase, reflecting the gradual dissipation of excess pressure as the system approaches equilibrium. The pressure decline goes into negative, meaning that the pressure level becomes lower than the initial pressure. This means that the pore volume is progressively expanding. Figure 10b displays the observed GWL changes at Well 5, Gyeong-Ju San-Nae. At the onset of the earthquake, there is a sharp rise in the GWLs, which closely correspond to the simulated instantaneous pore pressure increase seen in Figure 10a. Following the initial spike, the GWLs decrease gradually. This gradual decline aligns with the simulated decay phase of the pore pressure into negative. The pore pressure evolution simulated at the Well 8 location is presented in Figure 11. The Well 8 location corresponds to the GWL monitoring station 8, Gyeong-Ju Cheon-Buk. The modeled pore pressure curve is characterized by high-frequency fluctuation (Figure 11a), whereas the GWL changes were monitored at 1-day intervals (Figure 11b). The red arrow indicates the time of the GJEQ occurrence, which was at 256 days elapsed since 1 January 2016. The pore pressure exhibits an instantaneous and sharp rise at the moment of the earthquake, representing the rapid stress transfer caused by the fault rupture. After this abrupt increase, the pressure undergoes a slow decay phase, reflecting the gradualdissipation of excess pressure as the system approaches equilibrium. Despite the decline in the rate of increase, the pressure remains consistently positive, indicating that the pore pressure in the aquifer stabilizes at a higher level compared to its initial state. Figure 11b displays the observed GWL changes at Well 8, Gyeong-Ju Cheon-Buk. At the onset of the earthquake, there is a sharp rise in the GWLs, which closely correspond to the simulated instantaneous pore pressure increase seen in Figure 11a. Following the initial spike, the GWL continues to rise gradually, indicating a slower, sustained upward trend. The leveling-off of this rise reflects the decreasing rate of pressure increases, as observed in the simulated data (Figure 11a). Figure 9: Spatial distribution of pore pressure at simulation time of (**a**) 1.2 s, (**b**) 4.8 s, and (**c**) 10.8 s after start of fault rupture. Figures at different time instances are provided in the Supplementary Materials. Figure 11: (**a**) Pore pressure evolution simulated at the location of Well 8 in the model, corresponding to the location of Station 8 (Gyeong-Ju Cheon-Buk) and (**b**) GWL changes monitored at Station 8  
Figure 10: (**a**) Pore pressure evolution simulated at the location of Well 5 in the model, corresponding to the location of Station 5 (Gyeong-Ju Sen-Nae) and (**b**) GWL changes monitored at Station 5 Gyeong-Ju San-Nae. The horizontal axis is the elapsed days since 1 January 2016. The red arrow indicates the onset of the GWL changes induced by the GJEQ. Gyeong-Ju Cheon-Buk. The horizontal axis is the elapsed days since 1 January 2016. The red arrow indicates the onset of level changes induced by the GJEQ.