Mine Subsidence in Indiana

Abstract

About 100,000 acres of southwestern Indiana are undermined, but there are no estimates of the total acreage of subsidence damage. Subsidence is indicated by the formation of sinkholes, ponds, and troughs, alteration of the flow of ground water, and damage to manmade structures. The effects of subsidence, which are long lasting in many places and may not be eliminated by natural processes for decades or centuries, may be difficult to recognize and must be studied in the field and on aerial photographs. The character and areal extent of subsidence, as well as the time elapsed before its formation, depend on the layout of a mine, the methods used in mining, the depth of a mine, the character of the rocks and sediments overlying a mine, the flow of groundwater through the workings, and later human activity, such as surface mining. Because the initial stages of subsidence are hidden and because so many factors are involved, predicting subsidence above abandoned room-and-pillar mines for a particular locality is impossible. But as more information is gathered, determining probabilities of subsidence for selected sites may be possible.