Correction of seafloor magnetotelluric data for topographic effects during inversion
Chave, Alan D.
MetadataShow full item record
The large contrast in electrical conductivity between seawater and the underlying seafloor accumulates boundary electric charges which can severely distort observed electric and magnetic fields. For marine magnetotelluric (MT) studies, correcting this topographic effect is critical to obtaining accurate conductivity models for the mantle. Previously, correction for topography was based on the thin sheet approximation which breaks down at periods under ∼1000 s in the deep ocean. This paper introduces an analysis method for seafloor MT data which combines removal of three-dimensional (3-D) topographic effects with inversion of the data for 2-D structure. The observed MT impedance is first corrected to a flat-lying seafloor datum using the observed bathymetry without invoking the thin sheet approximation. The corrected MT response is then inverted in a flat seafloor model space. Because of coupling between topographic effects and deeper structure, the correction and inversion steps are iterated until changes in each become small. The procedure is verified using synthetic and real data. Tests for synthetic 3-D topography over a half-space show that the method closely recovers the true half-space model after a few iterations. The procedure is also applied to real data collected in the Mantle Electromagnetic and Tomography (MELT) experiment on the East Pacific Rise at 17°S.
Author Posting. © American Geophysical Union, 2005. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 110 (2005): B12105, doi:10.1029/2004JB003463.
Showing items related by title, author, creator and subject.
Lithospheric structure of an Archean craton and adjacent mobile belt revealed from 2-D and 3-D inversion of magnetotelluric data : example from southern Congo craton in northern Namibia Khoza, T. David; Jones, Alan G.; Muller, Mark R.; Evans, Rob L.; Miensopust, Marion P.; Webb, Susan J. (John Wiley & Sons, 2013-08-09)Archean cratons, and the stitching Proterozoic orogenic belts on their flanks, form an integral part of the Southern Africa tectonic landscape. Of these, virtually nothing is known of the position and thickness of the ...
Matsuno, Tetsuo; Chave, Alan D.; Jones, Alan G.; Muller, Mark R.; Evans, Rob L. (Oxford University Press on behalf of The Royal Astronomical Society, 2014-01-02)A robust magnetotelluric (MT) inversion algorithm has been developed on the basis of quantile-quantile (q-q) plotting with confidence band and statistical modelling of inversion residuals for the MT response function ...
Prediction of silicate melt viscosity from electrical conductivity : a model and its geophysical implications Pommier, Anne; Evans, Rob L.; Key, Kerry; Tyburczy, James A.; Mackwell, Stephen; Elsenbeck, James R. (John Wiley & Sons, 2013-06-12)Our knowledge of magma dynamics would be improved if geophysical data could be used to infer rheological constraints in melt-bearing zones. Geophysical images of the Earth's interior provide frozen snapshots of a dynamical ...