A single method for the inversion of anisotropic data sets with application to structural studies

In this paper, a single method for analysing magnetic susceptibility and P-wave velocity data is proposed, assuming that both measurement sets can be described by a second rank tensor, which is usually assumed for magnetic data only. For the velocity data, we estimate the discrepancy this hypothesis implies with respect to the theoretical P-wave velocity formulation for transverse isotropic media, with generalization for orthorhombic media. We find that the associated error in the determination of the principal values mostly lies below 1% when computed for published experimental data on sandstones and limestones. This result promotes the use of a unique and simple method for analysing anisotropy revealed by both physical properties, the advantage of which appears clearly in structural studies. We also check on our strategy for data sampling in order to get reliable outputs, and our statistical analysis shows that the measurement design used is suitable. The method is finally applied to a ramp-related fold structure in Corbières (France): we emphasize that combining data sets for different physical properties and using a single inversion scheme leads to a better understanding of the deformation processes at the microstructural scale, which can be related to structural features and tectonic settings.