USING PERSISTENT SCATTERER RADAR INTERFEROMETRY (DINSAR) TO MEASURE SUBSIDENCE RELATED TO ABANDONED UNDERGROUND MINING IN EASTERN AND SOUTHEASTERN OHIO

Roughly 800mi² of abandoned underground mine (AUM) land sits beneath Ohio land as a result of modern resource extraction (primarily coal) dating back to the early 1800’s. The number of confirmed abandoned mines throughout the state is currently at 4,786, but that number is considered to be a vast underestimate since mine operators were not required by law to provide documentation for their mines until 1874. The risks associated with mine subsidence are not only dangerous, but extremely costly as well. Remediation of gypsum mines beneath SR-2 near Toledo is predicted to cost $26,163,544, and will ultimately cost $169,238,295 to motorists forced to take the 19 mile detour throughout the project’s 3-year timespan. Until recently, it was difficult to “see” the expanse of underground mines, but improvements to georeferencing technology have made it possible. Wellston, a small city located in southeast Ohio, is situated above “mined-out” Quakertown no.2 coal. Traditionally, manual land surveying was needed to measure how much the land surface was subsiding, but the application of differential interferometric satellite aperture radar (DInSAR) provides a new, robust technique for quantifying subsidence over large areas (100km²) with extreme precision. We applied the persistent scatterer interferometry technique to 21 ERS-1 and ERS-2 overlapping scenes, along the same track, and determined relative motion of surfaces in Wellston. Interferometry results were superimposed existing abandoned mine maps and Ohio Mine Subsidence Insurance Underwriting Association (OMSIUA) sites. Results were then integrated into a GIS environment in order to aid in understanding, identifying, and quantifying where subsidence has occurred. These are used in a model to help identify causes for subsidence (rapid or gradual), identify locations throughout the city at high risk of future subsidences, and predict the cost of remediating the AUMs that threaten Wellston directly.