The magnetic gradient tensor of a triaxial ellipsoid, its derivation and its application to the determination of magnetisation direction

An AI approach to automated magnetic formation mapping beneath cover

“…and z is the target depth below the sensor Uopq is the inducing field strength t is the magnetic field inclination t is the magnetic field declination A first order detection for remanence is determined by a sign reversal of the vertical gradient component (( or the first invariant 8 at the centre of magnetisation. Beike et al (2012), Clark (2014) and McKenzie (2019) show that the inclination of the magnetisation of a compact source (including a dipole, sphere, ellipsoid and vertical pipe) can be calculated from the tensor measurement over the centre of magnetisation using the following formula:…”

“…where : is the second eigenvalue and is the normalised source strength. The declination of the magnetisation may be estimated from the x and y components of the second eigenvector (McKenzie, 2019). Note that the magnetisation direction cannot be determined for extremely elongate magnetic sources.…”

An AI approach to using magnetic gradient tensor analysis for quick depth and property estimation

“…The declination of the magnetisation may be estimated from the x and y components of each of the three eigenvectors (McKenzie, 2019). Note that the magnetisation direction cannot be determined for extremely elongate magnetic sources.…”