## 4 Results
### Annual Average Velocity of Surface Deformation  
The annual average deformation velocities of the study area from January 2018 to December 2023 are illustrated in Figure 5, with eight distinct hues representing velocity intervals ranging from \(-50\) mm/y to \(30\) mm/y. Negative values indicate surface subsidence, while positive values denote land uplift, as previously mentioned. Overall, the iliac color, representing the fastest subsidence velocity interval of \(-50\) mm/y to \(-40\) mm/y, is predominantly observed in the southeastern mining fields of the study area. This suggests that surface subsidence velocities are more rapid in the southeast zones compared to the northwest. Detailed information, including the maximum and average subsidence velocities in the twelve zones, is provided in Table 4. Among the twelve zones, there are two zones that exhibit maximum subsidence velocities exceeding \(-40\) mm/y, which are the southernmost mining field zone C7 (\(-46.45\) mm/y) and the zone relating to the easternmost small coal mine reconstruction area R4 (\(-45.74\) mm/y), respectively. There are three zones situated between C7 and R4, and two northernmost zones, where the maximum subsidence velocity surpasses \(-30\) mm/y. These zones, listed from fastest to slowest, are C8 (\(-38.82\) mm/y), R2 (\(-33.70\) mm/y), R1 (\(-33.37\) mm/y), C6 (\(-33.36\) mm/y), and C5 (\(-30.49\) mm/y). In contrast, the maximum subsidence velocity in the five zones between R4 and R1 is comparatively lower, with all exceeding \(-20\) mm/y. These zones, in order of decreasing velocity, are R3 (\(-28.89\) mm/y), C2 (\(-28.27\) mm/y), C4 (\(-25.06\) mm/y), C3 (\(-21.91\) mm/y), and C1 (\(-20.97\) mm/y). Additionally, we can also find that the average velocity of surface subsidence in zone C7 is the highest, indicating that mining-induced surface subsidence is most pronounced in this region. Across all subsidence zones, velocities gradually decrease from the subsidence center toward the margins. Such high annual average subsidence velocities are likely to have significant impacts on ecological environment protection and geological disaster prevention.  
\begin{table}
\begin{tabular}{c c c} \hline \hline \multirow{2}{*}{**Zone**} & **Maximum Velocity of Surface** & **Average Velocity of Surface** \\  & **Subsidence (mm/y)** & **Subsidence (mm/y)** \\ \hline R1 & \(-33.37\) & \(-6.47\) \\ R2 & \(-33.70\) & \(-7.62\) \\ R3 & \(-28.89\) & \(-7.71\) \\ R4 & \(-45.74\) & \(-8.85\) \\ C1 & \(-20.97\) & \(-7.36\) \\ C2 & \(-28.27\) & \(-7.73\) \\ C3 & \(-21.91\) & \(-7.22\) \\ C4 & \(-25.06\) & \(-8.99\) \\ C5 & \(-30.49\) & \(-10.96\) \\ C6 & \(-33.36\) & \(-8.62\) \\ C7 & \(\mathbf{-46.45}\)1 & \(\mathbf{-11.08}\) \\ C8 & \(-38.82\) & \(-9.03\) \\ \hline \hline \end{tabular} \({}^{\dagger}\) The bold font number represents the maximum value in each column.  
\end{table}
Table 4: Details of annual average subsidence velocities in 12 zones.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Zone**} & **Subsidence Area (km\({}^{2}\))** & **Maximum Cumulative** & **Average Cumulative** \\  & **Subsidence (mm)** & **Subsidence (mm)** \\ \hline R1 & 14.01 & \(-219.91\) & \(-35.98\) \\ R2 & \(\mathbf{17.75}\)\({}^{\dagger}\) & \(-179.41\) & \(-34.69\) \\ R3 & 9.32 & \(-174.91\) & \(-39.54\) \\ R4 & 14.53 & \(-265.11\) & \(-41.56\) \\ C1 & 6.76 & \(-129.4\) & \(-38.25\) \\ C2 & 5.18 & \(-148.01\) & \(-35.61\) \\ C3 & 7.71 & \(-137.31\) & \(-34.69\) \\ C4 & 6.80 & \(-136.91\) & \(-36.48\) \\ C5 & 9.26 & \(-162.61\) & \(\mathbf{-49.15}\) \\ C6 & 4.97 & \(-179.91\) & \(-33.7\) \\ C7 & 3.64 & \(\mathbf{-283.41}\) & \(-37.25\) \\ C8 & 9.80 & \(-203.81\) & \(-44.03\) \\ \hline \hline \end{tabular} \({}^{\dagger}\) The bold font number represents the maximum value in each column.  
\end{table}
Table 3: Details of cumulative subsidence in 12 zones on 18 December 2023.