Measuring Subsidence Above Abandoned Underground Mines in Ohio Using Persistent Scatter Intereferometry (PInSAR)
Throughout the 1800’s and still today, coal mining practices, primarily room-and-piller mining, have resulted in a very intricate system of caverns and void space beneath urban locations in Ohio. Not until 1874 were mine operators required by law to prepare and submit maps of their operations. Subsidence associated with the abandoned underground mining (AUM) operations in Ohio continue to be a dangerous and costly problem, as there are currently 4,786 AUMs confirmed throughout the state. The tortuous and sporatic nature of the coal seams, combined with poor documentation of mining locations, continues to make predicting subsidence difficult in this area. An example of the type of risk associated with these mines is located near Toledo, where the Ohio Department of Transportation (ODOT) has estimated that it will spend $26,163,544 over 960 days on mine remediation below SR-2, which would in total cost $169,238,295 to motorists forced to take the 19 mile detour. Geo-referenced mine maps have brought light to the extent of much of the abandoned underground mine land in Ohio. One of these locations is Wellston, located in southeastern Ohio, where the downtown area lies above “mined-out” Quakertown no.2 coal. The advent of Differential Interferometric images derived from repeat-pass Synthetic Aperture Radar (SAR) technology provides a cost effective method for quantifying subsidence at a large scale (100km²), with extreme precision (<0.1mm). Results from interferometry were superimposed existing abandoned mine maps and documented subsidence locations. This allows interferometry results to be analyzed in an integrated GIS environment, and aids in understanding, identifying, and quantifying where subsidence has occurred. These are used in a model to help identify causes for subsidences (rapid or gradual), with the potential of identifying locations at high risk of future subsidences.
AAPG Search and Discovery Article #90154©2012 AAPG Eastern Section Meeting, Cleveland, Ohio, 22-26 September 2012