Three-dimensional inversion of magnetotelluric impedance tensor data and full distortion matrix

Avdeeva, Anna, Moorkamp, Max, Avdeev, D., Jegen, Marion and Miensopust, M. (2015) Three-dimensional inversion of magnetotelluric impedance tensor data and full distortion matrix Geophysical Journal International, 202 (1). pp. 464-481. DOI 10.1093/gji/ggv144.

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Galvanic distortion of magnetotelluric (MT) data due to small-scale surficial bodies or due to topography is one of the major factors that prevents accurate imaging of the subsurface. We present a 3-D algorithm for joint inversion of MT impedance tensor data and a frequency-independent full distortion matrix that circumvents this problem. We perform several tests of our algorithm on synthetic data affected by different amounts of distortion. These tests show that joint inversion leads to a better conductivity model compared to the inversion of the MT impedance tensor without any correction for distortion effects. For highly distorted data, inversion without any distortion correction results in strong artefacts and we cannot fit the data to the specified noise level. When the distortion is reduced, we can fit the data to an RMS of one, but still observe artefacts in the shallow part of the model. In contrast, in both cases our joint inversion can fit the data within the assumed noise level and the resulting models are comparable to the inversion of undistorted data. In addition, we show that the elements of the full distortion matrix can be well resolved by our algorithm. Finally, when inverting undistorted data, including the distortion matrix in the inversion only results in a minor loss of resolution. We therefore consider our new approach a promising tool for the general analysis of field MT data.

Document Type: Article
Additional Information: WOS:000360623400033
Keywords: Inverse theory, Electromagnetic theory, Magnetotellurics
Research affiliation: OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-GDY Marine Geodynamics
Refereed: Yes
DOI etc.: 10.1093/gji/ggv144
ISSN: 0956-540X
Date Deposited: 28 Sep 2015 08:42
Last Modified: 03 May 2017 09:31

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