Modeling-Assisted InSAR Phase-Unwrapping Method for Mapping Mine Subsidence

Compared with traditional measurement technologies, synthetic aperture radar interferometry (InSAR) has unique advantages in monitoring ground subsidence due to underground mining. However, when the subsidence gradient of the subsidence trough exceeds the maximum measurable gradient of InSAR technology, the interference fringes will be too dense, causing phase aliasing. As a result, it is impossible to obtain correct phase-unwrapping result. The main objectives of this letter are two folded. First is to develop an unwrapping strategy to deal with the unwrapping problem caused by large subsidence gradient at the mine subsidence trough. The main idea of this strategy is to estimate most of the subsidence phase by multiple model inversions based on iterative approach. Then, the model phases from multiple models are combined with the final unwrapped residual phase. Another objective of this letter is to evaluate the feasibility of the three common deformation models, i.e., Mogi, probability integral method (PIM), and Okada, in solving the phase-unwrapping problem. Their advantages and disadvantages are outlined. Both the simulated data and real data are used for this experiment. The result shows that the problem of large subsidence gradient in the differential interferometric synthetic aperture radar (DInSAR) results can be solved by multiple model inversion. Among the three models, the use of Okada model seems to provide slightly more accurate result for solving the large-scale subsidence in the mining area than the other two models with the proposed strategy.