Abstract
We evaluate the possible factors contributing to surface subsidence due to abandoned room and pillar coal mines of southwest Indiana, where underground coal mining has been active since the 19th century. Because data were limited for older mines, we had to apply some indirect analysis procedures. Each contributing factor was evaluated in a statistically appropriate manner to determine the significance of its contribution to subsidence. This significance is determined by the weight of the factor in a scoring model, which prioritizes the need for grouting within an area at risk of subsidence. The goal of this study is not to determine a method that predicts precisely where and when subsidence will occur but rather to provide a system by which the relative likelihood of subsidence in a particular area can be ranked. This ranking can then be used to assist the Indiana Department of Natural Resources' Division of Reclamation in scheduling grouting operations and minimizing future subsidence hazards. The ranking system also indicates marginally stable areas where subsurface drilling would provide greater accuracy.