USING DIFFERENTIAL SYNTHETIC APERTURE RADAR INTERFEROMETRY (DINSAR) TO DETECT SUBSIDENCE RELATED TO ABANDONED UNDERGROUND MINES (AUMS) IN SOUTHEASTERN OHIO

The Ohio Department of Natural Resources (ODNR) Geologic Hazards division estimates that roughly 8,000 abandoned underground mines (AUMs) exist beneath the surface of Ohio’s historic coal mining region. The number of confirmed AUMs was recently updated to near 6,000, accumulating to about 800mi² in total. Subsidence of the land above the AUMs has become a serious issue for counties with historical AUMs because it poses threats to the health and wellbeing of people, but also poses extreme risks to structures above the AUM land. In the past, efforts to monitor subsidence have been sparse, leading to an incomplete understanding of how subsidence is related to the abandoned mine geometry. This has led to many instances where an individual may purchase “cheap” land above an AUM without knowledge of the AUM. Traditionally, repeat land surveying was used to measure subsidence in these areas, however, more recently, the application of differential synthetic Aperture radar interferometry (DInSAR) has provided the user the ability to systematically measure miniscule land surface displacements (<0.1mm) through time. 38 ERS-1 and ERS-2 scenes that spanned the time between 1993 and 2003 were used to monitor subsidence of Wellston, OH. Wellston sits above several ~100 year old room-and-pillar mines, and at least 15 subsidence claims have been funded by the office of surface mining abandoned mine land inventory system (OSM AMLIS) within 5km²of downtown. Interferometry results were superimposed existing abandoned mine maps from the ODNR’s online abandoned mine locator GIS and OSM AMLIS sites. Results were integrated into a GIS to better understand, identify, and quantify how subsidence has developed in Wellston. By comparing interferometry results to existing OSM AMLIS sites and mine maps, the effectiveness of radar interferometry for this application was assessed.