Coal Subsidence Mapping Project and Report Completed

Recent coal mine subsidence beneath a school in Benld, Illinois, has drawn increased attention to the importance of documenting and locating old mine workings. More than 4,000 underground mines with known locations have operated in Illinois. All but 12 coal mines and 10 industrial minerals/metals mines have been abandoned. Although subsidence has occurred over all types of mines in Illinois, most subsidence is related to coal mines because of the extensive areas underlain by these mines. However, one of the state's largest subsidence events occurred over a lead-zinc mine near Galena, Illinois.

The Illinois State Geological Survey (ISGS) has released Circular 575, The Proximity of Underground Mines to Urban and Developed Lands in Illinois, authored by Christopher Korose, Andrew Louchios, and Scott Elrick. The circular is an update of a 1991 study and contains maps and statistics per county on the proximity of both coal and non-coal underground mined areas to urban development The present study reflects newly available data and a revised assessment methodology that incorporates a mine depth, rules-based approach within the spatial calculations. Results of this study found that an estimated 333,000 housing units and approximately 201,000 acres of urban and developed lands are in close proximity to underground mines and may be exposed to subsidence. The work was funded, in part, by the Illinois Mine Subsidence Insurance Fund.

Map showing the relationship of Zone 1, (land over the mapped mine extent and adjacent land), and Zone 2, (additional land beyond Zone 1), to mined areas and urban land cover classifications.