The application of differential interferometric synthetic aperture radar to identify, measure, and analyze subsidence above underground coal mines in Utah

Subsidence is a major consequence of underground mining. Over 1000 underground coal mines are operating in the United States and affect a surface area of more than 1 million hectares. Surface subsidence associated with underground coal mining is expected to remain a major environmental and engineering issue. The comprehensive subsidence engineering and management to characterize the nature, extent, and magnitude of expected and actual surface displacements are developed while simultaneously identifying subsidence impacts with high risk levels and/or severe consequences. This is a difficult task and one that is currently limited by shortcoming in data collection and assessment. Differential Interferometric Synthetic Aperture Radar (DInSAR) is a growing technology in surface displacement monitoring and has the potential to improve the efficiency and accuracy of subsidence monitoring by significantly increasing the quantity and accuracy of measurement data. In this study, the validation of DInSAR was conducted with respect to four underground coal mines in Utah. The subsidence associated with pillar collapse at Crandall Canyon mine and longwall panel extraction at Deer Creek mine, Dugout Canyon mine, and West Ridge mine were used to compare DInSAR derived subsidence measurements with traditional field data collection methods. The comparison to the mine development history in all four mines showed that the DInSAR measured subsidence troughs correlated well with the mine location, and the troughs development indicated to follow the longwall face advance. At Crandall Canyon mine, the DInSAR measured the subsidence of 27.5 cm, which compares favorably to 30 cm of GPS measurement. At Dugout Canyon mine, the maximum rate of subsidence of 14 cm per month was measured using DInSAR, while the GPS showed a maximum rate of 10 cm per month. Measurement using DInSAR above a second panel at Dugout Canyon mine during 2006 and 2007 indicated 18 cm of subsidence, nearly identical to the 20 cm measured via GPS. At Deer Creek and West Ridge mines, the DInSAR results correlate well with field data collected via an aerial photogrammetric survey.