Magnetometry and Gradiometry for Archaeological Prospection: Developments in Ground and UAV-Based Surveys.

Applied geophysics provides a range of non-invasive techniques that allow researchers to detect buried structures and characterize the physical properties of materials in archaeological contexts. Among the different geophysical approaches, the magnetic method is widely used because it is efficient, relatively fast, cost-effective, and non-destructive. This technique exploits variations in magnetic susceptibility between archaeological features and the surrounding soil. Such contrasts generate small disturbances in the measured Earth’s magnetic field, known as magnetic anomalies, which can be analysed to identify and map subsurface remains. However, anomalies produced by archaeological targets are usually weak, localized, and often overlap with one another. For this reason, the acquisition of high-resolution magnetic data is crucial.

One particularly effective application of the magnetic method in archaeology is the use of gradiometric surveys. In this configuration, the magnetic gradient is measured rather than the total magnetic field. This approach enhances the visibility of shallow sources and significantly improves data resolution. Gradiometric systems usually employ two sensors positioned at different heights, allowing the instrument to emphasize local anomalies while reducing the influence of regional magnetic fields and temporal variations. As a result, features related to archaeological remains can be identified more clearly.

In recent years, advances in applied geophysics have further improved data acquisition through the use of Unmanned Aerial Vehicles (UAVs) equipped with miniaturized magnetometers. UAV-based magnetic surveys enable the rapid investigation of large areas at low altitudes, producing high-resolution datasets. This technology is particularly valuable in environments where traditional ground surveys are difficult to perform.

We showcase the potential and latest advancements in the use of both ground- and UAV-based magnetometric sensors, also in vertical gradiometer configurations, for the discovery and diagnosis of archaeological remains.