# Key Strata Identification of Overburden Based on Magnetotelluric Detection: A Case Study
## 5 Conclusions  
1. Overburden failure will inevitably lead to the changing of electromagnetic characteristics. Due to the different degrees of failure, the overburden AR characteristics with different buried depths are different. In theory, the more severe of overburden failure after mining, the greater change of apparent resistivity.
2. According to the field application, the strata characteristics revealed by MT detection are consistent with KS, especially in the aspect of lithology, mechanical properties, failure characteristics, and electromagnetic response characteristics, which provides a basis for the analysis of KS in MT detection.
3. Based on the comparison between field application and analysis, MT detection can be used as a convenient and fast method to identify the overburden KS by analyzing the AR characteristics, which provides a new technical support for the mine pressure control, construction of digital model, and precise mining.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Number**} & \multirow{2}{*}{**Lithology**} & \multirow{2}{*}{**Thickness \(h\) (m)**} & \multicolumn{2}{c}{**Bulk Density \(\gamma\)**} & \multicolumn{2}{c}{**Elastic Modulus \(E\)**} & \multicolumn{2}{c}{**Tensile Strength \(\sigma_{c}\)**} & \multirow{2}{*}{**KS Location**} \\  & & & **(kg/m3)** & & & **(GPa)** & **(MPa)** \\ \hline
1 & Aeolian sand & 8.75 & 1600 & / & / & \\
2 & Silstone & 7.02 & 2650 & 40 & 3.83 & \\
3 & Coal & 0.98 & 1400 & / & 0.80 & \\
4 & Silstone & 11.68 & 2650 & 40 & 3.83 & \\
5 & Sandy mudstone & 1.9 & 2520 & 18 & 1.53 & \\
6 & Silstone & 14.56 & 2650 & 40 & 3.83 & PKS \\
7 & Fine sandstone & 1.56 & 2680 & 37 & 2.70 & \\
8 & Sandy mudstone & 3.1 & 2520 & 18 & 1.53 & \\
9 & Fine sandstone & 0.62 & 2680 & 37 & 2.70 & \\
10 & Silstone & 12.05 & 2650 & 40 & 3.83 & SKS \\
11 & Kern stone & 3.36 & 2580 & 27 & 2.10 & \\
12 & Fine sandstone & 12.7 & 2680 & 37 & 2.70 & \\
13 & Silstone & 1.3 & 2650 & 40 & 3.83 & SKS \\
14 & Mudstone & 0.1 & 2250 & 8 & 1.23 & \\ \hline \hline \end{tabular}
\end{table}
Table 2: Mechanical parameters of overlying strata and KS location.  
**Author Contributions:** Conceptualization, [PERSON] ([PERSON]), [PERSON], and E.B.; formal analysis, [PERSON] ([PERSON]), W.G., and E.B.; funding acquisition, W.G.; investigation, [PERSON] ([PERSON]), [PERSON], and [PERSON] ([PERSON]); methodology, W.G.; software, [PERSON] ([PERSON]); supervision, W.G.; writing--original draft, [PERSON] ([PERSON]) and [PERSON] All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research was financially supported by the National Natural Science Foundation of China (51774111), the Key Project of the National Natural Science Foundation of China (U1810203), and the Innovation and Outstanding Talent Project of Henan Province Science and Technology (184200510003).  
**Acknowledgments:** This research was financially supported by the National Natural Science Foundation of China (51774111), the Key Project of the National Natural Science Foundation of China (U1810203), and the Innovation and Outstanding Talent Project of Henan Province Science and Technology (184200510003). The authors thank the anonymous reviewers for their careful work and thoughtful suggestions that have helped improve this paper substantially.  
**Conflicts of Interest:** The authors declare no conflict of interest.