Two-dimensional geomagnetic forward modeling using adaptive finite element method and investigation of the topographic effect

Forward modeling approach is a major concept in geophysical exploration and also a key factor in the development of inversion algorithms. Finite element method for two-dimensional (2-D) geomagnetic forward modeling is based on numerical solution of the Laplace equation. In this paper we present a fa...

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Vydáno v:Journal of applied geophysics Ročník 105; s. 169 - 179
Hlavní autoři: Jeshvaghani, Mehdi Shahmirzae, Darijani, Mehrdad
Médium: Journal Article
Jazyk:angličtina
Vydáno: Elsevier B.V 01.06.2014
Témata:
2-D
Algorithms
Finite element
Finite element method
Forward modeling
Galerkin methods
Geomagnetic
Geomagnetism
Geophysics
Mathematical analysis
Mathematical models
Topography
Triangular grid
Triangular grid
2-D
Forward modeling
Geomagnetic
Topography
Finite element
ISSN:0926-9851, 1879-1859
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Shrnutí:Forward modeling approach is a major concept in geophysical exploration and also a key factor in the development of inversion algorithms. Finite element method for two-dimensional (2-D) geomagnetic forward modeling is based on numerical solution of the Laplace equation. In this paper we present a fast and accurate adaptive finite element algorithm for forward modeling of 2-D geomagnetic structures. Our method is stable and is reliable to recover 2-D magnetization distribution with complex shapes. It uses an unstructured triangular grid which allows modeling the complex geometry with the presence of topography. The Galerkin's method is used to derive the systems of equations. Then, the conjugate gradient solver with incomplete LU decomposition as the pre-conditioner is used to solve the system of equations. To ensure numerical accuracy, iterative mesh refinement is guided by a posteriori error estimator. We validate our algorithm in simple geometry by analytical technique. The tests on synthetic data illustrate a good performance of the method in mapping the complex geometry of the magnetic sources with topography. The magnetic responses of the model have proved to be different in the presence of topography. Therefore, it is highly recommended to consider the effects of topography on interpretation. Finally, we applied numerical FEM algorithm to real data set providing fine recovery model of the shallow high mineralized crustal setting of Soltanieh region, Iran. •We present finite element algorithm for forward modeling of 2D magnetic structures.•We validate our algorithm in simple geometry by analytical technique.•Method allows us to model when the ground surface has the magnetic susceptibility.•The magnetic responses are different in the presence and absence of the topography.•The tests on synthetic and real data illustrate a good performance of the method.
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ISSN:0926-9851
1879-1859
DOI:10.1016/j.jappgeo.2014.03.016