Geoelectric Investigations with Special Measurement Geometry to Delimit Prehistoric Mining Areas in Hallstatt

Summary The Hallstatt area in Austria has a very long history of salt mining, which was frequently interrupted by large landslides. Landslide material filled the prehistoric underground mining chambers and therefore conserved their dimensions. Within several geoelectric measurement campaigns, data from ground surface measurements and from geoelectric profiles in 2 mining tunnels from the 18th century were collected, resulting in a 3D data set of about 80,000 data points. The aim was to track a mining chamber of the Early Iron Age, which has been filled with landslide material. The already existing reconstruction of this mining chamber is based on several archeological excavation points and an interpolation in between. A collapsed mining shaft known from laser scan data has been confirmed beforehand with surface ERT measurements. Due to the high resistive salt rock and the hardness and dryness of the intruded landslide material, the Early Iron Age mining chamber could not be differentiated sufficiently. Instead, results could pinpoint that the mining chambers are following the area of the highest electrical resistivity, which is determined as “Haselgebirge” in geological maps. Therefore, indications of the location of the Early Iron Age mining chamber, where no archaeological finds exists until now, could be given.