## 3 Study Area and Data Source Analysis
### Data Source and Feature Analysis
Shot points were spaced 20 m apart, and receiver points 10 m apart. In practice, shots S21 and S25 were not fired, resulting in data acquisition from 38 shots and 1596 data points (Table 2). \begin{table}
\begin{tabular}{c c c c c c c c c c c c c c} \hline \hline  & **BK1-1** & **2-HB1** & **HS-5** & **2-1** & **HS-4** & **HS-3** & **HS-2** & **HS-1** & **3-2** & **326** & **BK5** & **3-3** & **4-5** & **4-4** \\ \hline Q\({}_{4}\) & 36.25 & 7.50 & 27.40 & 54.18 & 25.00 & 46.00 & 26.00 & 45.80 & 46.42 & 76.91 & 39.44 & 57.00 & 26.30 & 51.60 \\ \hline N\({}_{2}b\) & 0.00 & 56.30 & 55.80 & 29.62 & 45.04 & 41.08 & 64.49 & 36.80 & 43.98 & 0.00 & 75.91 & 31.50 & 59.43 & 44.25 \\ \hline J\({}_{2}y^{3}\) & 48.15 & 34.28 & 35.89 & 42.25 & 35.81 & 29.42 & 34.49 & 21.90 & 22.10 & 25.47 & 27.29 & 19.00 & 21.88 & 25.55 \\ \hline J\({}_{2}y^{2}\) & 76.13 & 77.50 & NaN & 79.05 & NaN & NaN & NaN & NaN & 81.40 & 80.17 & NaN & 79.35 & 69.86 & 80.85 \\ \hline J\({}_{2}y^{1}\) & 19.75 & 14.43 & NaN & 10.60 & NaN & NaN & NaN & NaN & 10.45 & 30.15 & NaN & 12.76 & 14.41 & 14.69 \\ \hline  & 4-6 & 5-2 & 332 & 5-3 & BK3-2 & 6-6 & 6-5 & B6 & B7 & B8 & B9 & B10 & B12 & \\ \hline Q\({}_{4}\) & 42.95 & 24.19 & 90.29 & 30.60 & 0.00 & 22.45 & 42.60 & 60.40 & 63.80 & 53.90 & 46.50 & 88.25 & 40.55 & \\ N\({}_{2}b\) & 39.10 & 59.04 & 0.00 & 38.30 & 92.00 & 63.24 & 47.10 & 17.80 & 27.00 & 26.40 & 21.20 & 14.45 & 53.00 & \\ \hline J\({}_{2}y^{3}\) & 20.23 & 32.49 & 23.01 & 15.40 & 11.30 & 24.05 & 21.00 & 27.07 & 28.27 & 20.32 & 25.80 & 32.97 & 30.15 & \\ \hline J\({}_{2}y^{2}\) & 56.52 & 79.79 & 64.42 & 68.25 & 58.70 & 51.06 & 71.00 & 68.49 & 65.53 & 78.90 & 65.40 & 68.05 & NaN & \\ \hline J\({}_{2}y^{1}\) & 9.50 & 9.88 & 10.17 & 8.85 & 10.78 & 11.16 & 6.85 & 17.40 & 23.48 & 11.97 & 25.12 & 22.87 & NaN & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Formation thickness data (m). The channel wave exploration results indicate that the coal seam thinning zone correlates with a high-velocity anomaly. Figure 8 presents the seismic record for shot S11 in the 25214 workforce. The magenta line represents an auxiliary line at 925 m/s, while the green line demonstrates the actual arrival time of each channel wave. From this figure, the channel wave velocity is approximately 925 m/s for receivers 1 through 29. However, arrivals at receivers 30 through 42 exhibit an earlier arrival time, indicating a velocity increase and, therefore, coal seam thinning. Picking different channel waves produces the velocity distribution across the workforce (Figure 9). While the channel wave velocity is generally stable, the data define an anomalous high-velocity range, referred to as SYC1. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Workface**} & **Name of** & **Stimulate** & **Number** & **Distance Between** & **Receive Point** & **Receive the** & **Number** & **Receive Point** \\  & **Roadway** & **Point Number** & **Points** & **Firing Points (m)** & **Number** & **Number** & **of Points** & **Spacing (m)** \\ \hline \multirow{3}{*}{25214} & Return wind & S1–S20 & 20 & 20 & R43–R84 & 42 & 10 \\ \cline{2-7}  & Shipping & S2–S24 & 18 & 20 & R1–R42 & 42 & 10 \\ \cline{2-7}  & Subtotal & & 38 & & & 84 & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Channel wave construction data point. Figure 6: 25214 workforce coal seam thickness data source. Figure 7: Channel wave layout drawings. High-velocity anomalies typically indicate local coal seam thinning or the presence of a sandstone scoured zone, as channel waves travel faster in sandstone than in coal. In the SYC1 region, on-site observations confirmed that the coal seam thinning was caused by a localized sandstone scour body. This scour body replaced part of the coal seam with harder sandstone, resulting in a velocity increase in the channel wave propagation. Notwithstanding their dense and uniform distribution across the workface, the inverted coal thickness data from channel waves are considered \"soft data\", indicating lower precision and uncertainty.