The magnetic geophysical technique is used to explore the spatial distribution of magnetized rocks and buried ferrous objects. Data is acquired at or near the surface in a non-invasive way.

The most common magnetic method is magnetic gradiometry. A magnetic gradiometer is formed by constructing an array of two or more magnetometers. A gradiometer measurement is the difference between the measurements from the two magnetometer sensors. In comparison to a single magnetometer, the data from a gradiometer can reveal substantially finer details concerning the spatial variations of the magnetic signature of magnetized subsurface bodies.

Magnetic gradient map
Magnetic gradient map showing buried reinforced concrete pipes crossing a field