## 5 Discussion  
Compared with traditional monitoring methods, the overall situation related to large-scale surface subsidence in the Wanli mining area monitored by the SBAS-InSAR technique is presented more intuitively and more completely in the results. We can clearly divide the 12 zones into underground coal mines (C1, C2, C4, C5, C6, C7, C8) and open-pit coal mines (R1, R2, R3, R4, C3). Due to diverse approaches with respect to exploration of coal resources, the subsidence characteristics of the two kinds of coal mines are quite different. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Panel** & **Quantity** & **No. 1** & **Length (m)** & **Orientation A 2** & **Orientation B 3** & **Consistency 4** \\ \hline \multirow{4}{*}{301} & \multirow{4}{*}{5} & 1 & 206 & SE-NW & SE-NW & Yes \\ \cline{3-6}  & & 2 & 113 & SE-NW & NE-SW & No \\ \cline{3-6}  & & 3 & 78 & E-W & E-W & Yes \\ \cline{3-6}  & & 4 & 95 & NE-SW & NE-SW & Yes \\ \cline{3-6}  & & 5 & 52 & NE-SW & NE-SW & Yes \\ \hline \multirow{4}{*}{203} & \multirow{4}{*}{12} & 6 & 73 & E-W & E-W & Yes \\ \cline{3-6}  & & 7 & 34 & NE-SW & NE-SW & Yes \\ \cline{3-6}  & & 8 & 200 & N-S & N-S & Yes \\ \cline{3-6}  & & 9 & 29 & NE-SW & NE-SW & Yes \\ \cline{3-6}  & & 10 & 25 & NE-SW & NE-SW & Yes \\ \cline{3-6}  & & 11 & 164 & SE-NW & NE-SW & No \\ \cline{3-6}  & & 12 & 83 & NE-SW & NE-SW & Yes \\ \cline{3-6}  & & 13 & 25 & SE-NW & SE-NW & Yes \\ \cline{3-6}  & & 14 & 20 & E-W & E-W & Yes \\ \cline{3-6}  & & 15 & 58 & SE-NW & SE-NW & Yes \\ \cline{3-6}  & & 16 & 36 & E-W & E-W & Yes \\ \cline{3-6}  & & 17 & 152 & SE-NW & SE-NW & Yes \\ \hline \multirow{4}{*}{401} & \multirow{4}{*}{12} & 18 & 131 & SE-NW & SE-NW & Yes \\ \cline{3-6}  & & 19 & 55 & SE-NW & SE-NW & Yes \\ \cline{3-6}  & & 20 & 45 & SE-NW & SE-NW & Yes \\ \cline{3-6}  & & 21 & 77 & E-W & E-W & Yes \\ \cline{3-6}  & & 22 & 102 & E-W & NE-SW & No \\ \cline{3-6}  & & 23 & 21 & E-W & NE-SW & No \\ \cline{3-6}  & & 24 & 21 & E-W & E-W & Yes \\ \cline{3-6}  & & 25 & 78 & NE-SW & NE-SW & Yes \\ \cline{3-6}  & & 26 & 48 & NE-SW & NE-SW & Yes \\ \cline{3-6}  & & 27 & 47 & NE-SW & NE-SW & Yes \\ \cline{3-6}  & & 28 & 29 & NE-SW & NE-SW & Yes \\ \hline \multicolumn{6}{l}{29} & 108 & NE-SW & NE-SW & Yes \\ \hline \hline \end{tabular}  
* \({}^{1}\)“No.” refers to the numbering system for the 29 ground fractures, assigned sequentially from north to south within each mining panel. 2 “Orientation A” refers to the orientation of the ground fracture. 3 “Orientation B” refers to the orientation of the tangent line at the subsidence margin corresponding to the ground fracture. 4 “Consistency” refers to whether the orientation of the ground fracture conforms to the orientation of its corresponding subsidence margin tangent.  
\end{table} 
Table 5: Specific structural conditions of 29 ground fractures. The area of subsidence in open-pit coal mines is much larger than the area of subsidence in underground coal mines because the step-like slopes in the large occupied area are needed in open-pit coal mines for transport, while they are not required in underground coal mines [41, 42]. Furthermore, considering the mines in terms of high yields and high efficiency, coal resources are excavated from smaller areas of underground coal mines [43], which leads to the steep boundaries of subsidence funnels, further inducing the appearance of ground fractures. Therefore, it is in the boundaries of subsidence funnels that geological disasters are prone to occur. If not monitored and controlled over time, these boundaries are likely to cause the expansion of ground fractures, and even collapses. However, the central area of each mining subsidence zone has experienced severe short-term subsidence, resulting in decorrelation in the SBAS-InSAR monitoring results. More decoherence areas emerge in open-pit coal mines than in underground coal mines because of the extent of severe deformation over a short time interval induced by open-pit mining [44, 45, 46, 47].