2D and 3D Resistivity Tomography for the Detection of an Ancient Tunnel in Lavrion Area (Greece)

At the archaeological site of Bertseko, in Laurion, the entrance of an ancient tunnel was found during archaeological excavations. After approximately 15 m the tunnel remains inaccessible – blocked with filled materials. 2d and 3d resistivity measurements were carried out in order to delineate the direction of the tunnel and to evaluate the effectiveness of resistivity imaging technique to detect such targets. Firstly, eight 2d resistivity profiles were carried out with the pole-pole array in a non-rectangular grid, in order to image a wider area, a greater depth, and to avoid several surface obstacles. Then the most promising area from the previous procedure was outlined and selected for analysis with 3d resistivity tomography (pole-dipole array) for better resolution. The field strategy adopted improves the delineation and the definition of the target and avoids the loss of valuable information with respect to the object under investigation. The integrated results from both 2d pole-pole and 3d pole-dipole profiles provide answers to archaeologist’s questions, delineate with great accuracy the direction of the tunnel and give rise to new aspects for the improvement of subsurface imaging and acquisition strategy.