Everywhere on the Earth there is a natural magnetic field generated by electrical currents in the outer core and lower mantle. These currents generate a permanent magnetic field. The horizontal component of this magnetic field can orient a horizontally free-moving magnetisable needle (magnetic compass) in the direction towards the magnetic north. The magnetic field is a vector field, i.e. it can be described by its magnitude and direction. The magnetic field consists of three parts: (1) the primary magnetic field whose origin is within the Earth; (2) a fluctuating time varying field, whose origin is outside the Earth, e.g. generated by the sun and supernovas; (3) And a local anomaly field, whose origin is a result from the magnetization of material in the upper crust .

Ground based magnetometry is carried out by measuring the local anomaly field using a magnetometer and therefore examines the distribution of magnetic minerals in the subsurface. Since the content of such minerals varies between different types of rocks, magnetic data can be used to identify and delimit lithological units, deformation zones and provide information about the amount and proportion of different magnetic minerals. Magnetometry is commonly used in mineral exploration but is also used in archaeology and environmental investigations.

Reference projects:

– Various confidential exploration surveys
– Detection of iron waste such as buried barrels in an industrial site in Gothenburg.