The 2D electrical resistivity tomography method was used to study the geometry of coal seams at two sites that differ in the local geological setting and type of coal. One site contains a lignite seam whereas the other contains an anthracite seam. The coal seam resistivity signatures were determined and the results were compared between the two study sites. The interpreted 2D resistivity tomograms showed that the lignite seam cannot be distinguished from the surrounding host rocks but the anthracite seam is clearly associated with high resistivity values up to 100 Ωm with respect to the low-resistivity background of shale. The type and age of coal affects the porosity and water saturation. Increases in these two parameters reduce the bulk resistivity of the formation. Type, age, and fluid content are important factors that determine the resistivity contrast of a coal seam with the surrounding rocks.
