## 6 Conclusions  
This study constructed a 3D geometric model of the main active faults in the Linfen Basin by interpreting deep seismic reflection profiles and velocity structure data. Based on this model, we elucidated the seismic environment of the Linfen Basin and the relationship between two large historical earthquakes. We reached the following conclusions:  
1. The 1695 Linfen earthquake occurred in the velocity transition zone above the low-velocity body, and a few small earthquakes occurred in this area. However, the 1303 Hongtong earthquake occurred in an area with high P-wave velocity and a high density of small earthquakes. This indicates differences in the seismic environments between the two earthquakes. A low-velocity body developed at a depth of 16-21 km in the southern part of the Linfen Basin, leading to differences in seismogenic environments between the northern and southern parts of the Linfen Basin, which is in good agreement with the current distribution of small earthquakes. 2. Based on the 3D geometric model of the Huoshan Fault, the maximum fracture area was calculated, and then the maximum magnitude of the 1303 Hongtong earthquake was estimated. The results show that the magnitude of the 1303 Hongtong earthquake was overestimated. 3. Based on the 3D model, we performed Coulomb stress analysis between the two large earthquakes. The results show that the 1303 Hongtong earthquake had an obvious stress-loading effect on the 1695 Linfen earthquake. In this study, we constructed a 3D seismic structure model of the Linfen Basin based on existing data. In subsequent research, we will continuously update the model with an abundance of data to attain a more precise model. We can deploy a deep seismic profile in the northern part of the Linfen Basin to constrain the geometry of faults in the northern basin, thereby analysing the differences in deep structures between the southern and northern parts of the basin more effectively. The following supporting information can be downloaded at [[https://www.mdpi.com/article/10.3390/app14188412/s1](https://www.mdpi.com/article/10.3390/app14188412/s1)]([https://www.mdpi.com/article/10.3390/app14188412/s1](https://www.mdpi.com/article/10.3390/app14188412/s1)). Figure S1. Coulomb stress effect of the 1303 Hongtong earthquake (hypocenter depth of 15 km and rupture length of 45 km) on the 1695 Linfen earthquake. The yellow pentagram represents the 1303 Hongtong earthquake, the red pentagram represents the 1695 Linfen earthquake, red circles indi-cate earthquakes after 1303 (M \(\geq\) 5), solid black lines represent faults, and solid green lines represent rupture faults. Cross-sections at depths of (a) 15 km and (b) 20 km. Figure S2. Coulomb stress effect of the 1303 Hongtong earthquake (hypocenter depth of 15 km and rupture length of 85 km) on the 1695 Linfen earthquake. The yellow pentagram represents the 1303 Hongtong earthquake, the red pentagram represents the 1695 Linfen earthquake. Cross-sections at depths of (a) 15 km and (b) 20 km. Figure S3. Coulomb stress effect of the 1303 Hongtong earthquake (hypocenter depth of 20 km and rupture length of 45 km) on the 1695 Linfen earthquake. The yellow pentagram represents the 1303 Hongtong earthquake, the red pentagram represents the 1695 Linfen earthquake, red circles indi-cate earthquakes after 1303 (M \(\geq\) 5), solid black lines represent faults, and solid green lines represent rupture faults. Cross-sections at depths of (a) 15 km and (b) 20 km. Conceptualisation, R.L. and Z.H. ; formal analysis, Z.G. and G.L. ; investigation, J.Y. and F.S. ; writing--original draft preparation, Z.G., R.L. and Z.H. ; writing--review and editing, R.L. and Z.G. ; funding acquisition, R.L., F.S. and X.Y. All authors have read and agreed to the published version of the manuscript. This research was supported by the project of Institute of Geology, China Earthquake Administration (IGCEA2205), and the Linfen Development and Reform Commission (1521044025). Not applicable.