## 5 Discussion
### Relationship between Two Historical Large Earthquakes  
After a strong earthquake occurs, the stress state of the seismogenic area changes, which may delay or promote the occurrence of earthquakes on active faults in adjacent areas. Numerous studies on earthquake-triggering relationships have shown that earthquakes can interact with each other [80; 81; 82]. In this study, Coulomb stress analysis was conducted using the Coulomb 3.4 software package. During the process, Poisson's ratio was set to 0.25, and the friction coefficient, to 0.4 [53; 54]. The fault slip distribution of the Hongtong earthquake was used as the source fault, and the fault geometry of the Linfen earthquake was used as the receiving fault. The Coulomb stress changes caused by the 1303 Hongtong earthquake on the 1695 Linfen earthquake were calculated at depths of 15 km and 20 km, respectively. Previous studies have revealed that the seismogenic fault of the 1303 Hongtong earthquake was the Huoshan Fault [33; 76]. However, there is controversy regarding the seismogenic fault of the 1695 Linfen earthquake, and the relationship between the two earthquakes is not clear. Studies on historical earthquakes indicate that the Luoyunshan Fault produced five earthquakes in the past 37,000 years, and the most recent of which was a \(\mathbf{M}\) 6.5 event in 649 C.E. [83]. Thus, it is unlikely that the Luoyunshan Fault was responsible for the 1695 Linfen earthquake (Figure 2a). Some scholars consider that the Guojiazhuang Fault is the seismogenic fault of the 1695 Linfen earthquake [17; 35; 36; 37]. However, the Guojiazhuang Fault is only 25 km long and has been considered incapable of producing a \(\mathbf{M}\) 7.8 earthquake. Researchers have speculated that the combined rupture of the Guojiazhuang and Luoyunshan faults produced the 1695 Linfen earthquake [38]. This conflicts with the findings of seismic studies that focused on the Luoyunshan Fault [83]. No shallow crustal faults matching the 1695 Linfen \(\mathbf{M}\) 7.8 earthquake have been observed in the southern part of the basin. [PERSON] et al. [46] summarised the focal mechanism solution parameters of 49 earthquakes in North China (\(\mathbf{M}\geq\) 6.5), including the focal parameters of the Hongtong and Linfen earthquakes, as shown in Table 1. However, the hypocenter depths of these two historical earthquakes are uncertain. The seismogenic fault of the 1303 Hongtong earthquake is the Huoshan Fault; however, its rupture length is controversial. Through surface geological surveys, [PERSON] and [PERSON] (1990) determined the length of the fault zone to be 45 km [76]. However, [PERSON] et al. (2018) estimated the length of the fault zone to be 90 km based on ancient exploration trench research [33]; the modelling length for this study was 85 km. Because of the uncertainties in the hypocenter depth and rupture length, we selected rupture lengths as 45 km and 85 km and the hypocenter depths as 15 km and 20 km for the simulation of the 1303 Hongtong earthquake. We used the rupture geometric structure of the 1695 Linfen earthquake as the receiving fault (Table 1), with an effective friction coefficient of 0.4. We assessed the impact of Coulomb stress changes caused by the 1303 Hongtong earthquake on the 1695 Linfen earthquake. The simulation results show that the change in Coulomb rupture stress (\(\Delta\)CFS) at the epicentre of the 1695 earthquake is greater than 0.1 bar. The maximum value was 2.543 bar, and the minimum value was 1.008 bar at the reference depths of 15 km and 20 km, respectively, with different source parameters of the 1303 earthquake (Table 2). Most \(M\geq\) 5.0 earthquakes in the Linfen and Taiyuan basins after the 1303 Hongtong earthquake (Table 3) are 1.008 and 1.008 respectively. The 1303 Hongtong earthquake (Table 4) is 1.008 and 1.008 respectively. The 1303 Hongtong earthquake (Table 5) is 1.008 and 1.008 respectively. The 1303 Hongtong earthquake (Table 6) is 1.008 and 1.008 respectively. The 1303 Hongtong earthquake (Table 7) is 1.008 and 1.008 respectively.