## 5 Discussion  
We examine the impact of varying input parameters individually on the computational outcomes to assess their sensitivity. Figure 5 illustrates the impact of various parameters on the computed outcomes (specific calculated values see Table S6 in Supplementary Materials). The blue regions indicate the range of calculated results when altering these parameters. The red dotted lines represent the results of the calculations in the previous chapter. The calculated results we used and the results after changing the parameters are the data at 10 km depth in the vertical plane of AB in Figure 4. The effective friction coefficient varies from 0.2 to 0.6, the maximum Coulomb stress changes difference reaches 1.67 bar, and the mean Coulomb stress changes difference is about 0.28 bar. [PERSON]'s ratio exhibited a range of 0.2 to 0.3, with the maximum discrepancy in the calculated Coulomb Failure Stress reaching 0.87 bar, and the average error is about 0.09 bar. [PERSON]'s modulus ranged from 70 MPa to 90 MPa, and the difference in the error of the calculated results is between 0 and 1.65 bar. The orientation of principal stress axes is determined by six parameters (azimuth and plunge of S1, S2, S3). To assess the impact of these parameters on Coulomb stress changes, we independently adjusted each of the six parameters. Specifically, we altered the azimuth by 72\({}^{\circ}\) and the plunge by 18\({}^{\circ}\). Despite these adjustments, the calculated results remained consistent with the original findings, indicating that Coulomb stress changes exhibit minimal sensitivity to variations in the orientation of principal stress axes. This phenomenon can be attributed to the principal stress direction serving as a macroscopic representation of the stress tensor, with its changes contributing relatively little to local stress variations. Alterations in the principal stress direction influence Coulomb stress changes primarily through modifications in normal and shear stresses at the fault plane. However, this effect is indirect and often overshadowed by the direct influences of fault geometry and slip direction. Figure 5: The sensitivity of Coulomb stress changes to different parameters. The blue area is the range of variation calculated by changing the corresponding parameter. The red dashed lines represent the results used in this study. The data in this figure correspond to the data at 10 km depth in the AB vertical plane in Figure 4. The horizontal coordinates correspond to the position of the AB straight line. (**a**) Sensitivity of friction; (**b**) sensitivity of Poisson’s ratio; (**c**) sensitivity of Young’s modulus; (**d**) sensitivity of Principal stress; (**e**) sensitivity of strike; (**f**) sensitivity of dip; (**g**) sensitivity of rake; (**h**) sensitivity of source location. In addition, we investigated how changes in the focal mechanism affected the \(\Delta CFS\). We changed the focal mechanism of the 7.7 Mw earthquake in 2023. This is because the event was close to the AB vertical and caused Coulomb stress changes that were large in both value and extent. This analysis allowed for an examination of how deviations in the focal mechanism influence the computational outcomes. We constrained the variations in strike and rake to within 10 degrees and dip within 5 degrees. Our findings revealed that altering the strike significantly influences the Coulomb stress changes, with an average difference of about 1.33 bars. The difference is more significant at locations close to the epicenter, which can reach about 4 bar. The calculations are much less sensitive to dip and rake than to strike, which have average errors of about 0.37 bar and 0.43 bar. These discrepancies were predominantly observed in the vicinity of the 7.7 \(M\)w earthquake, particularly in the section adjacent to the A-side of the AB line. Additionally, we investigated the influence of the seismic source location on the computed results by displacing the source of the 7.7 Mw earthquake by 5 km along the AB line towards sections A and B.