Two-decadal evolution of irreversible surface deformation in a coal mining area revealed by improved InSAR observations

Abstract

High-intensity mining activities caused by the rapid increase of coal consumption can lead to unprecedented multi‑hazard effects of underground coal mining. Revealing the long-term surface deformation of a coal mining area plays an important role in understanding a disaster. However, due to the limitation of methods and data, the long-term evolution effect of surface deformation in coal mining regions remains unclear. Here, we improved the Interferometric Synthetic Aperture Radar (InSAR) method to process multi-source radar remote sensing monitoring data from the past twenty years to uncover the long-term surface deformation throughout the study region. We found that the initial scattered smaller deformation areas detected by Generic Atmospheric Correction Online Service (GACOS)-assisted Stacking gradually merged into a coherent larger region. Our Improved Interferometric Point Target Analysis (IPTA)-InSAR method showed that coal mining activities can lead to significant surface deformation that can last for several years. The velocity-involved stability assessment method assesses the stability in a mining area using historical time series, so as to judge the current state of this area. Results revealed that GACOS-assisted Stacking is more suitable for extracting surface deformation from coal mining activities at the regional scale as it greatly reduces topographic and atmospheric errors during the data processing. Additionally, the correction effect of GACOS datasets on C-band datasets is better. Meanwhile, we discuss the limitations of proposed stability assessment method. This study provides a new understanding of surface deformation caused by coal mining activities.