Assessing the State of Conservation of a Masonry Building through the Combined Use of Electrical and Seismic Tomography

An integrated geophysical approach encompassing electrical resistivity and seismic tomography investigations is presented in this work, for assessing the current state of conservation of a Roman masonry building located in the Ostia Antica archaeological site (Rome, Italy), affected by rising damp and cracking phenomena. A preliminary three-dimensional electrical survey aims to detect the foundations and understand the range of variation of the resistivity at the study site. High-Resolution electrical and seismic tomography lines were later acquired on an inner wall, prone to both rising damp and cracking. The combined use of electrical and seismic tomography allows us to obtain a high-resolution map of the wall made in opus caementicium, where low resistivity and P-wave velocity values can be associated to the presence of the inner mortar, while higher values are probably due to the outer brick component. Overall, with reference to a previous laboratory work on a Roman masonry sample analysed using seismic tomography, we rate the brick part in good conditions while the low velocity values of the mortar can potentially represent an anomaly due to degradation processes. This approach can be employed to reconstruct a three-dimensional model of the surveyed wall in order to plan recovery actions.