Abstract
We presented a 2.5D inversion algorithm with topography for frequency-domain airborne electromagnetic data. The forward modeling is based on edge finite element method and uses the irregular hexahedron to adapt the topography. The electric and magnetic fields are split into primary (background) and secondary (scattered) field to eliminate the source singularity. For the multisources of frequency-domain airborne electromagnetic method, we use the large-scale sparse matrix parallel shared memory direct solver PARDISO to solve the linear system of equations efficiently. The inversion algorithm is based on Gauss-Newton method, which has the efficient convergence rate. The Jacobian matrix is calculated by “adjoint forward modelling” efficiently. The synthetic inversion examples indicated that our proposed method is correct and effective. Furthermore, ignoring the topography effect can lead to incorrect results and interpretations.
Highlights
As an important geophysical prospecting method, the frequency-domain airborne electromagnetics is widely used in fields of mineral survey, geological mapping, groundwater resource exploration, environmental monitoring, and so forth
This paper, based on vector finite element method, adopts PARDISO to solve the linear system of equations, subdivides the model in irregular hexahedral mesh, makes 3D forward modeling in topography, and employs Gauss-Newton method to carry out 2D inversion of frequency-domain airborne electromagnetics with topography, providing an effective mean to calculate, process, and interpret the aeroelectromagnetic data for mountainous areas
The primary field under the uniform whole space medium or under the layered medium is calculated by analytic solution, while the secondary field is calculated by vector finite element method
Summary
As an important geophysical prospecting method, the frequency-domain airborne electromagnetics is widely used in fields of mineral survey, geological mapping, groundwater resource exploration, environmental monitoring, and so forth. Newman and Alumbaugh made 3D finite difference calculation and simulated the impact from simple topography upon the observed data results in 1995 [2]. Sasaki and Nakazato simulated the topography’s impact upon the observed result by finite difference calculation and made an attempt to find a way to eliminate this impact in 2003, concluding that no way but making inversion with the topography taken into account can eliminate the impact from the topography [3]. This paper, based on vector finite element method, adopts PARDISO to solve the linear system of equations, subdivides the model in irregular hexahedral mesh, makes 3D forward modeling in topography, and employs Gauss-Newton method to carry out 2D inversion of frequency-domain airborne electromagnetics with topography, providing an effective mean to calculate, process, and interpret the aeroelectromagnetic data for mountainous areas
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
