Characterization of Potential Mine Subsidence Areas in Indiana
Since underground coal mining began in Indiana in the mid-1800s, an estimated 100,000 ac have been undermined. Although this area is mostly rural, some Hoosier towns and cities, including parts of Evansville, Bicknell, Boonville, Linton, Jasonville, and the suburbs of Terre Haute have also been undermined.
The Indiana Geological Survey (IGS) and the Indiana Division of Reclamation (IDOR) began a cooperative project in 1981 to gather information about Indiana coal mines and to make this information available to the public. The first product of this cooperative effort was a series of quadrangle maps showing locations of underground coal mines documented by company mine maps. In 1986 the IGS, with funding from the IDOR, began a project that combined information from these underground coal mine maps and from other coal-related maps with other geologic information from the Department of Natural Resources to produce a set of maps showing key factors related to mine subsidence. The maps show outlines of undermined areas, thickness of the unconsolidated material, depth of mine workings, shaft d pth, and bedrock geology.
Project maps cannot be used to predict the precise location or timing of subsidence, but rather they summarize factors known to be related to subsidence risk and severity. The maps indicate known mined areas where subsidence can occur and areas where unmapped mines are likely to be located. The maps have proved most useful to homeowners, insurance companies, government agencies, and the coal industry.
AAPG Search and Discovery Article #91023©1989 AAPG Eastern Section, Sept. 10-13, 1989, Bloomington, Indiana.