Show simple item record

dc.contributor.authorSchmoldt, J.-P.
dc.contributor.authorJones, A. G.
dc.date.accessioned2018-09-20T16:24:08Z
dc.date.available2018-09-20T16:24:08Z
dc.date.issued2013-10-07
dc.identifier.citationSchmoldt, J.-P. Jones, A. G. (2013). A novel anisotropic inversion approach for magnetotelluric data from subsurfaces with orthogonal geoelectric strike directions. Geophysical Journal International 195 (3), 1576-1593
dc.identifier.issn0956-540X,1365-246X
dc.identifier.urihttp://hdl.handle.net/10379/13831
dc.description.abstractThe key result of this study is the development of a novel inversion approach for cases of orthogonal, or close to orthogonal, geoelectric strike directions at different depth ranges, for example, crustal and mantle depths. Oblique geoelectric strike directions are a well-known issue in commonly employed isotropic 2-D inversion of MT data. Whereas recovery of upper (crustal) structures can, in most cases, be achieved in a straightforward manner, deriving lower (mantle) structures is more challenging with isotropic 2-D inversion in the case of an overlying region (crust) with different geoelectric strike direction. Thus, investigators may resort to computationally expensive and more limited 3-D inversion in order to derive the electric resistivity distribution at mantle depths. In the novel approaches presented in this paper, electric anisotropy is used to image 2-D structures in one depth range, whereas the other region is modelled with an isotropic 1-D or 2-D approach, as a result significantly reducing computational costs of the inversion in comparison with 3-D inversion. The 1- and 2-D versions of the novel approach were tested using a synthetic 3-D subsurface model with orthogonal strike directions at crust and mantle depths and their performance was compared to results of isotropic 2-D inversion. Structures at crustal depths were reasonably well recovered by all inversion approaches, whereas recovery of mantle structures varied significantly between the different approaches. Isotropic 2-D inversion models, despite decomposition of the electric impedance tensor and using a wide range of inversion parameters, exhibited severe artefacts thereby confirming the requirement of either an enhanced or a higher dimensionality inversion approach. With the anisotropic 1-D inversion approach, mantle structures of the synthetic model were recovered reasonably well with anisotropy values parallel to the mantle strike direction (in this study anisotropy was assigned to the mantle region), indicating applicability of the novel approach for basic subsurface cases. For the more complex subsurface cases, however, the anisotropic 1-D inversion approach is likely to yield implausible models of the electric resistivity distribution due to inapplicability of the 1-D approximation. Owing to the higher number of degrees of freedom, the anisotropic 2-D inversion approach can cope with more complex subsurface cases and is the recommended tool for real data sets recorded in regions with orthogonal geoelectric strike directions.
dc.publisherOxford University Press (OUP)
dc.relation.ispartofGeophysical Journal International
dc.subjectinverse theory
dc.subjectnumerical approximations and analysis
dc.subjectelectromagnetic theory
dc.subjectmagnetotelluric
dc.subjectgalvanic distortion
dc.subjectimpedance tensor
dc.subjectnear-surface
dc.subject2-dimensional interpretation
dc.subjectelectromagnetic induction
dc.subjectsedimentary basin
dc.subjectdecomposition
dc.subjecttomography
dc.subjectalgorithm
dc.subjectmedia
dc.titleA novel anisotropic inversion approach for magnetotelluric data from subsurfaces with orthogonal geoelectric strike directions
dc.typeArticle
dc.identifier.doi10.1093/gji/ggt355
dc.local.publishedsourcehttps://academic.oup.com/gji/article-pdf/195/3/1576/1741141/ggt355.pdf
nui.item.downloads0


Files in this item

This item appears in the following Collection(s)

Show simple item record