On the use of electrical resistivity tomography in shallow water marine environment for archaeological research

This work concerns the use of electrical resistivity tomography method for the recognition of archaeological features in shallow water marine environment. Methodological problems due to the presence of a high conductive layer that affects signal to noise ratio are added to the resolution needed in the archaeological research. Goal of present work is to improve knowledge about the influence of water layer thickness and electrical conductivity on the signal to noise ratio and on the model constraint in the inversion process. Furthermore the choice of the appropriate position of the electrodes array with respect to the water layer as well as the right choice of the quadrupole to use has been analyzed. A methodological approach based on numerical simulation models, field data and real case studies has been followed. Field data and real case studies have been explored in the old town of Mothia, in the Pantaleo Island, Sicily and in the lagoon of Nora, in Sardinia. Results provide a detailed outline about the issues and the possible choices to optimize acquisition and the data processing and also demonstrate the great effectiveness of the method in detecting submerged archaeological features, the stratigraphy of the sea bed and other resistivity anomalies.