## 5 Discussion
### Earthquake Hazard Assessment Along the XSHFZ  
During an earthquake cycle, the seismic moment accumulation on a fault zone tends to balance with the amount of release [72]. The long-term potential earthquake hazard of a fault zone can be evaluated based on the principle of moment equilibrium, which assesses the relationship between the accumulation rate and the release rate of seismic moments [73]. The magnitude of a potential earthquake on a given fault zone can be further estimated from the seismic moment deficit. The seismic moment accumulation rate \(M_{0}^{a}\) of each segment of the XSHFZ accompanied with creep motion can be obtained by Equation (2) [74]. \[M_{0}^{a}=\mu L(V_{i}d_{1}-V_{c}d_{2}) \tag{2}\]  
where \(L\) is the length of the fault segment;\(V_{i}\) and \(V_{c}\) are the long-term slip rate and creeping rate during the interseismic period; \(d_{1}\) is the locking depth; \(d_{2}\) is the bottom depth of the creeping movement; \(\mu\) is the shear modulus, typically taking the value of 30 GP. The seismic moment release on a fault zone can be obtained using Equation (3) [75]. \[M_{w}=\frac{2}{3}\log M_{0}^{e}-6.03 \tag{3}\]  
where \(M_{0}^{e}\) is the seismic moment released by one earthquake and \(M_{w}\) represents the moment magnitude. The surface wave magnitudes are commonly used in China to represent earthquake magnitudes. However, the seismic moment release can be estimated by incorporating magnitudes from all seismic catalogs as the actual calculation's moment magnitude [76,77], based on previous research findings that suggest a minimal difference between \(M_{w}\) and \(M_{8}\)[78]. The completeness and reliability of a strong earthquake catalog are essential for accurately estimating seismic moment release and seismic moment deficit, and analyzing the background of seismic hazard in a region. Previous studies have indicated that the earthquake catalog for events of \(M_{8}\) 6.5 or higher since 1725 [41] and for events of magnitude 6 or higher since 1879 [35,79] in the XSHFZ is complete. Based on the above earthquake catalog (Table S1), combined with the geometric lengths, slip rates, and locking depths of each fault segment, the seismic moment accumulation and release for each fault segment were calculated and analyzed (Figure 11a,b). Subsequently, the seismic moment deficit and the corresponding potential earthquake magnitudes were calculated (Figure 11c). The results indicate that the five segments of the XSHFZ have a potential risk of earthquakes with magnitudes of 6.5 or higher. The segments of Luhuo, Daofu, and Moxi in the XSHFZ are still in a phase of seismic moment surplus, lacking sufficient seismic moment accumulation for strong earthquakes in the short term. However, the Qianning segment, the Yalahe fault, and the Selaha fault (Kangding segment) pose risks of earthquakes with magnitudes of 6.9, 6.9, and 6.6, respectively. The results are generally in line with the research conducted by [PERSON] et al. [76]. However, there are slight differences in our interpretation of the Daofu segment and the Moxi segment compared to the findings presented by [PERSON] et al. [30] and [PERSON] et al. [66]. Previous studies mainly concentrated on determining the moment magnitude related to energy accumulation since the latest large earthquake, without considering the notion of the earthquake cycle. In contrast, the results in this study cover a more extensive timeframe, ranging from the beginning of a comprehensive earthquake catalog until the present day. Moreover, the results are in good agreement with the seismic gaps located on the XSHFZ, as illustrated in Figure 2, which coincidentally fall within the Qianning and Kangding segment. It is important to monitor the seismic hazard in the two segments in the future. The strain rate field derived from geodetic data can indicate the buildup of strain in a region.