Surface Deformation Monitoring in Coal Mine Area Based on PSI

It is difficult to get robust deformation results using conventional differential interferometric synthetic aperture radar (D-InSAR) method, due to the limitation of the phase measurement error, baseline error, and atmospheric delay in synthetic aperture radar (SAR) interferometry. Persistent scatterer interferometry (PSI) represents a powerful tool to measure mining subsidence, as it offers a synoptic view that can be repeated at different time intervals and at various scales. In many cases, PSI data are integrated with in situ monitoring instrumentation, since the joint use of satellite and ground-based data facilitates the geological interpretation of mining subsidence and allows a better understanding of mining subsidence geometry and kinematics. In this paper, PSI interferometry and conventional ground-based monitoring techniques have been used to characterize and to monitor Ge-Ting mining located in Shandong, China. The PSI technique used in this paper overcomes most of the limitations of conventional interferometric approaches by identifying, within the area of interest, a set of “radar benchmarks” (PS), where very precise displacement measurements can be carried out. More than 78000 PS were identified by processing SAR images acquired from 2004 to 2009 by the ENVISAT. The PSInSAR application at a sub-regional scale detected slow ground deformations ranging from 0 to -58 cm/year and resulting from various processes (swelling/shrinkage of clay soils and water pumping). The results reveal the evolution process of “bowl” in mining subsidence and are helpful to the early warning of the mine disaster.