Journal Articles Geophysical Journal International Year : 2020

Retrieving lithospheric magnetisation distribution from magnetic field models

F Vervelidou
  • Function : Author

Abstract

We investigate to which extent the radially averaged magnetisation of the lithosphere can be recovered from the information content of a spherical harmonic model of the generated magnetic field combined with few simple hypotheses. The results obtained show firstly that a hypothesis of magnetisation induced by a field of internal origin, even over a localised area, is not sufficient to recover uniquely the radially averaged magnetisation and, secondly, that this magnetisation can be recovered when a constant magnetisation direction is assumed. An algorithm to recover the magnetisation direction and distribution is then described and tested over a synthetic example. It requires to introduce a cost function that vanishes when estimated in a system of coordinate with its Z axis aligned with the magnetisation direction. Failing to find a vanishingly small value for the cost function is an indication that a constant mag-netisation direction is not a valid hypothesis for the studied magnetic field model. The range of magnetisation directions that are compatible with the magnetic field model and a given noise level, can also be estimated. The whole process is illustrated by analysing a local, isolated maximum of the Martian magnetic field.

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hal-02996557 , version 1 (09-11-2020)

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V Lesur, F Vervelidou. Retrieving lithospheric magnetisation distribution from magnetic field models. Geophysical Journal International, 2020, ⟨10.1093/gji/ggz471⟩. ⟨hal-02996557⟩
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