## 1 Introduction  
Earthquakes are one of the most influential disasters in the entire life cycle of engineering structures [1]. To avoid damage to engineering structures caused by earthquakes, seismic hazard analysis methods can be used to predict the probability of earthquakes of various strengths in the future and prevent them in their structural designs [2]. Seismic hazard analysis includes the deterministic and probabilistic methods [3]. The deterministic seismic hazard analysis (DSHA) requires the prior determination of the seismic source and magnitude, but neglects the uncertainties in the data and calculations, which could lead to an overestimation of the risk for the seismic source with longer return periods or an underestimation of the risk for the seismic source with shorter return periods. Since Cornell proposed the probabilistic seismic hazard analysis method in 1968, this method has been used in the context of engineering design and in the verification of the performance requirements of structures induced by earthquakes [4]. The probabilistic seismic hazard analysis (PSHA) has been generally recognized as the rational method to quantify seismic threats [5]. The PSHA includes four aspects (as shown in Figure 1): (1) the seismic source characteristics, (2) the relationship between the magnitude and the frequency of the earthquake, (3) the attenuation relationship of the ground motion parameters, and (4) the hazard curve [6]. However, there are three uncertainties in the analysis process: the determination of the potential seismic source area, the estimation of the seismicity parameters, and the relationship between the parameters [7]. Surrounding the uncertain factors, how to improve the PSHA is the focus of scholars' continuous research. Researchers have refined the uncertainties in the determination of potential seismic source regions caused by an incomplete understanding of subsurface structures and earthquakes by adjusting the seismic zoning and seismic source models [8; 9]. The most important method to determine the potential seismic source area is to gain an in-depth understanding of the geological structural parameters, such as the soil parameters [10] and regional tectonic distribution characteristics [11], along with the deep earth tectonic [12] and seismic zone distributions [13]. In addition, the parameters of the seismic source mechanism can be effectively solved by defining the different seismic source models. The fact that these parameters vary widely in space and time, combined with the effect that different geological formations are interacting systems, makes the accurate analysis of potential seismic source zones very difficult [14; 15]. Continuous refinement of seismic zoning can precisely determine the parameters of the area and apply them to calculate the PSHA for each differential zone; however, detailed seismic zoning is not conducive to integration into region-wide, full-probability calculations [16]. Certain parameters, such as the average annual occurrence of earthquakes, earthquake magnitude values, and upper limits of earthquake magnitude, can lead to uncertainties in the valuation of the seismicity parameters. The seismic catalogue obtained from using seismic monitoring techniques can supplement this part of the parameters with a large number of actual measurements, but the number of such monitoring results is still limited by the capacity of the measuring instruments and the number of arrangements. To consider a more complete seismic catalogue, previous studies [17; 18] have combined the Monte-Carlo simulations of historical seismicity catalogues based on the measured data but may affect the accuracy of the PSHA. For the uncertainty underlying the determination of the potential seismic source regions and seismic activity parameter valuations, multiple combinations of scenarios may be used to calculate the seismic hazard analysis results of different scenarios while considering the  
Figure 1: Steps underlying PSHA.