## 5 Conclusions  
A geological model containing various fault zones was constructed, and synthetic data was used for forward modeling and inversion to replicate different survey designs. By analyzing how different survey parameters and model grids interpret fault zones in MT detection, we reached the following conclusions:  
1. Forward modeling results show that a station spacing of 400 m effectively resolves fault zones and transverse conductive fault zones ranging from 100 m to 400 m in width. However, reducing station spacing offers no significant advantage in accurately determining their extent and morphology. In contrast, larger station spacing impacts fault boundary localization and increases deviations from the actual geological model. Specifically, in Scenario 2, when station spacing exceeds 400 m, the imaging of both the F1 and F3 faults deteriorates, with lateral errors increasing from 0.1 km to as much as 1.2 km. These findings emphasize the need for tighter station spacing, particularly in complex geological regions, to achieve accurate fault localization.
2. In this study's geological model, using a 400 m station spacing, a survey length of 12 km or more yields optimal imaging accuracy for fault boundaries (F1 and F3), especially for narrower faults (Scenario 1), enhancing localization accuracy and inversion depth. For wider faults (Scenario 2), increasing the survey length does not significantly improve the clarity of the deeper faults. In both scenarios, the F1 fault is best imaged with a survey length of 12 km, where the lateral error in fault positioning decreases from 1.0 km to less than 0.3 km. For the F3 fault, a 12 km survey reduces its positional error from 1.5 km to 0.2 km. In contrast, the F2 fault consistently shows a shallower inversion depth, with reduced low-resistivity anomalies and an average depth discrepancy of 1.0 km across all survey lengths.
3. With a 400 m station spacing, broadband measurements do not significantly improve the clarity of shallow fault structures compared to regular measurements. This limitation may result from insufficient resolution of narrow fault structures in broadband data at a 400 m station spacing. Therefore, acquiring lower frequency and broader bandwidth data through long-period measurements is essential to improve the resolution of deep fault structures.
4. The inversion results in this study show a shallower inversion depth compared to the true depth, resulting in poor resolution of the faults' vertical extent. Additionally, the inversion results suggest that due to the limitations of MT inversion, resistivity models derived from MT data should be interpreted with caution, especially without support from other geophysical methods, as this may affect resource estimation. For instance, the F2 fault zone appears the smallest in the inversion results, with the resistivity model showing the poorest conductivity, contradicting its true characteristics but not diminishing its exploration potential. The forward modeling in this study has been optimized for a two-dimensional observation system, with simplifications made regarding subsurface structures and conductive materials. However, real-world conditions are likely more complex, requiring consideration of factors such as fault connectivity, variations in fault zones across planes, and the types of conductors involved.  
Conceptualization, H.Z.; methodology, H.Z.; validation, H.Z. and F.N.; formal analysis, F.N.; data curation, F.N.; writing--original draft preparation, H.Z.; writing--review and editing, H.Z. All authors have read and agreed to the published version of the manuscript.  
This research is funded by High-Level Talent Startup Project of North China University of Water Resources and Electric Power.  
The experimental data used to support the findings of this study are included in the manuscript.  
The authors declare no conflicts of interest.