Contribution of the Magnetic Horizontal Gradient Operator (MHGO) for the Interpretation of the Magnetic Anomalies

In this paper, we propose a high-resolution approach for detecting magnetic source boundaries. It depends on the application of the magnetic horizontal gradient operator (MHGO). The MHGO emphasizes the source effects, reducing the interference effects of the anomalies and yield an enhanced image of the boundaries. In order to illustrate the efficiency of the method, we describe the results obtained on the two archaeological sites: “Villa degli Antonini” (Genzano, Rome) and Rota Ria (Mugnano in Teverina, Viterbo) by the application of the detailed magnetic surveying. The results obtained have shown that the source boundaries locations are more precisely determined compared to those obtained with other known techniques which use the vertical gradient of the magnetic field. Since the main goal of the investigation was to understand and to high light the nature of the magnetic anomalies, different geophysical techniques (Electromagnetic and Ground penetrating radar surveying) were carried out. The final step of the investigation was the excavation in the targeted sector of the study areas in order to test the validity of the geophysical interpretations. The most interesting result was that, in both cases, the excavations have confirmed the results obtained during the magnetic surveying.