Forward modelling of magnetic anomalies in archaeological geophysics: A new software tool

We present a new software tool for the analysis and interpretation of archaeological magnetic anomalies, based on classical algorithms of forward modelling and a technique of error assessment. The proposed methodology allows us determining geometry, physical properties, and location of buried archaeological features, as well as the occurrence of fires or other historical events that may have affected the observed magnetic signal. In our approach, the acquisition of total field data, usually in a regular grid arrangement, their reduction to archaeological magnetic anomalies, and the subsequent computer-assisted structural interpretation are accomplished according to a specific workflow that conserves the physical meaning of the magnetic anomalies and excludes any kind of data processing that may change the nature of the anomaly field. In particular, the reduction of the observed total field data to magnetic anomalies is performed subtracting a polynomial representation of the regional field on the basis of a rigorous criterion that separates archaeological anomalies from geological (crustal) contributions, while procedures like line levelling or some kinds of data filtering are excluded to ensure a strict correspondence between magnetic data and the real distribution of magnetisation in the ground.