## 4 Subsidence Results and Comparison
The low coherence of the Sentinel-1 satellite, which falls below the unwrapping threshold, means that no phase unwrapping was performed, and consequently, no deformation results were obtained. In Figure 5g-i, pertaining to the second subsidence area, black dashed circles demarcate the subsidence range. The subsidence results for the Sentinel-1 data show a ratio of unwrapping errors of 60.2%, while the LT-1 data have a ratio of unwrapping errors of 8.5%, which means that the LT-1 results are more reliable. Figure 4: (**a**) Sentinel-1 satellite data subsidence monitoring results in the study area; (**b–d**) enlarged views of typical subsidence areas. In Figure 5j-l, the AA\({}^{\prime}\) profile line spans approximately 400 m within the first subsidence area. The LT-1 data capture this line across 168 pixels, in contrast to the 51 pixels in the Sentinel-1 data. Figure 6 presents the variation in subsidence values along the AA\({}^{\prime}\) profile line for both datasets. The average subsidence measured along this line is \(-\)8.2 mm for LT-1 and \(-\)3.9 mm for Sentinel-1, with a difference of 4.3. In addition, the maximum subsidence observed is \(-\)16.8 mm for LT-1 and \(-\)6.1 mm for Sentinel-1, with a difference of 10.7. The subsidence trends are similar for both datasets, showing gradual increases in subsidence from 0 to 180 m (T1), stabilization between 180 and 250 m (T2), and a decrease from 250 to 400 m (T3). The observed disparities in subsidence outcomes can be primarily ascribed to two key factors. Firstly, the higher resolution of the LT-1 imaging system contributes to a higher maximum detectable deformation gradient, thereby resulting in the large subsidence found. Secondly, the disparate wavelengths of the L-band and C-band SAR systems play a pivotal role. Higher coherence from the L-band provides more subsidence signals. Figure 5: (a,d,g,j) Results from LT-1 satellite data; (b,e,h,k) results from Sentinel-1 satellite data; (c,f,i,l) Google Earth optical images. The dashed circles are areas of subsidence, the AA\({}^{\prime}\) is profile line. Furthermore, it is important to note that while the deformation areas in the Sentinel-1 data may appear larger, this is partly due to the deformation scale used in the figures. Specifically, the deformation scale for Sentinel-1 was set to \(-10\) mm to \(10\) mm compared to \(-20\) mm to \(20\) mm for LT-1. This narrower scale for Sentinel-1 amplifies the visual representation of deformation, particularly in areas with high subsidence. However, as shown in Figure 6 where the data are analyzed quantitatively and in the real data and statistical results, the actual deformation areas detected by both satellites are found to be comparable. This clarification ensures a more accurate interpretation of the figures and subsidence measurements derived from the two datasets. A detailed quantitative analysis of the subsidence monitoring results from both SAR datasets is provided in Table 3, comparing RMSE, SD, and SNR in the study area. These metrics serve as overall accuracy indicators for interferometric phase unwrapping, evaluating the average error and overall deviation to determine the general suitability of the SAR data for the study area. Notably, the clarity of the interferometric phase-unwrapping results is pivotal in assessing subsidence monitoring quality, where SNR is a fundamental comparative measure, with higher noise levels correlating to lower SNR. The analysis reveals that the absolute value of the RMSE for Sentinel-1 data is 2.5 times that of LT-1, and the absolute value of the SD is 8 times higher. Additionally, the SNR for LT-1 data is 7.4 times greater than that for Sentinel-1. Collectively, the quality of LT-1's monitoring results surpassed those of Sentinel-1 in RMSE, SD, and SNR. The LT-1 data offer significantly higher precision in subsidence monitoring compared to Sentinel-1 data. In summary, the comparative analysis of LT-1 and Sentinel-1 data in monitoring mining-induced subsidence clearly demonstrates the superior performance of the LT-1 satellite.