Approximations for the 2-D coast effect on marine magnetotelluric data

Worzewski, Tamara, Jegen, Marion and Swidinsky, Andrei (2012) Approximations for the 2-D coast effect on marine magnetotelluric data Geophysical Journal International, 189 . pp. 357-368. DOI 10.1111/j.1365-246X.2012.05385.x.

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Marine natural source electromagnetic data acquired on continental margins are often of considerable scientific and commercial interest. However, the large conductivity contrast between the ocean and coast causes this type of data to be severely distorted. For a 2-D coastal model, this distortion is most pronounced for the marine magnetotelluric and geomagnetic response function derived from induced currents flowing parallel to the coast. A maximal distortion occurs for a given period at a specific distance from the coast and causes severe anomalies in the magnitude and phase of the response functions. Based on a modelling study, we empirically relate the characteristic period and characteristic distance to physical parameters such as the ocean depth and the host resistivity. Based on a simple analytical approach, we test these approximations and show that maximum distortion occurs when destructive interference between the ocean and host response is at its highest. While the coast effect causes a large distortion in the marine responses we show through a resolution analysis that it does not mask subsurface conductivity anomalies but in fact increases the sensitivity to the seafloor.

Document Type: Article
Additional Information: This article has been published in Geophysical Journal International ©2012 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Keywords: Geophysics; Electromagnetic theory; Magnetotelluric; Magnetic anomalies: modelling and interpretation; Magnetic field; Marine electromagnetics
Research affiliation: OceanRep > SFB 574
OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-GDY Marine Geodynamics
OceanRep > SFB 574 > N01
Refereed: Yes
DOI etc.: 10.1111/j.1365-246X.2012.05385.x
ISSN: 0956-540X
Projects: Future Ocean
Contribution Number:
SFB 574218
Date Deposited: 29 Jun 2011 08:52
Last Modified: 10 Jul 2018 09:36

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