## 2 Materials and Methods
### Source Model
#### 2.2.1 Slip Model 1  
[PERSON] et al.'s [55] result showed that the combined area of asperities, \(A_{\rm as}\), on average occupies 22% of the total rupture area, which can be shown as follows:  
\[A_{\rm as}=0.22\times L\times W \tag{5}\]  
Here, \(L\) and \(W\) are the rupture length and rupture width, respectively.  
The area of the largest asperity, \(A_{\rm a1}\), is approximately 16% of the total rupture area, and the area of the other asperity, \(A_{\rm a2}\), is 6% of the total rupture area:  
\[A_{\rm a1}=0.16\times L\times W \tag{6}\]  
\[A_{\rm a2}=0.06\times L\times W \tag{7}\]  
We assigned the asperities and other rupture areas different slips to appropriately represent the inhomogeneity of the stress and slip on the rupture area. The average slip of rupture area \(\bar{D}\) was calculated as follows [56]:  
\[\bar{D}=\frac{M_{0}}{\mu A} \tag{8}\]  
where \(\mu=3\times 10^{11}\rm{dyne/cm^{2}}\) is the average shear modulus of the crust, \(A\) is the rupture area, and \(M_{0}\) is the seismic moment. The seismic moment can be calculated based on the empirical relationship between the moment magnitude of the maximum credible earthquake and the seismic moment [57]:  
\[M_{\rm W}=\frac{2}{3}\log M_{0}-10.7 \tag{9}\]  
The ratio of the average slip on the asperities to the average slip over the whole rupture plane is independent of seismic moment, and the average value for the events studied was about 2 [55]. Thus, the average slip on the asperities, \(D_{\rm as}\), and on the other rupture areas, \(D_{\rm bk}\), can be calculated as follows:  
\[D_{\rm as}=2.0\times\bar{D} \tag{10}\]  
\[D_{\rm bk}=0.71\times\bar{D} \tag{11}\]  
Based on the slip distribution data from 13 earthquakes [55] and additional data from 16 earthquakes, [PERSON] [58] studied the characteristic parameters of asperities for shallow earthquakes. For a strike-slip fault, the semi-empirical relationship between the distance \(X_{\rm as}\) from the fault reference point to the center of the largest asperity along the strike direction and the rupture length is as follows:  
\[\log X_{\rm as}=\log L-0.30 \tag{12}\]  
The semi-empirical relationship between the distance \(Y_{\rm as}\) from the top depth of a fault to the center of the largest asperity along the dip direction and the rupture width is as follows:  
\[\log Y_{\rm as}=\log W-0.28 \tag{13}\]The empirical relationship between the length of the largest asperity, \(L_{\text{as}}\), and the fault rupture length is as follows:  
\[\log L_{\text{as}}=\log L-0.66 \tag{14}\]  
The empirical relationship between the width of the largest asperity, \(W_{\text{as}}\), and the fault rupture width is as follows:  
\[\log W_{\text{as}}=\log W-0.23 \tag{15}\]  
Referring to these empirical relationships, we determined the size and center location of the largest asperity on the fault rupture surface, which was in the middle of the F1-3 fault. In addition, another smaller asperity was set at the location closest to Site 1, which was tested to obtain the same results as setting it near Site 3, as shown in Figure 1b. Slip model 1, determined based on the empirical relationships, is shown in Figure 4a. The determined parameters are listed in Table 2.  
Figure 4: Schematic diagram of the source model. **(a)** Source Model 1, established from empirical relationships, and **(b)** Source Model 2. The red areas represent the asperities, the gray areas represent the other rupture area of the F1-3 fault, the blue stars represent the initial rupture points, and the arrows show different rupture schemes; the subfault size is 2 \(\times\) 2 km.