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Three-dimensional Modeling of GREATEM DataNormal access

Authors: T. Mogi, S. Abdallah and E. Fomenko
Event name: Near Surface Geoscience 2014 - 20th European Meeting of Environmental and Engineering Geophysics
Session: Modelling and Inversion I
Publication date: 08 September 2014
DOI: 10.3997/2214-4609.20142036
Organisations: EAGE
Language: English
Info: Extended abstract, PDF ( 884.33Kb )
Price: € 20

Summary:
The GREATEM (GRounded Electrical source Airborne Transient ElectroMagnetics) survey uses a grounded electrical dipole source of 2~3 km length as a transmitter and a three-component magneto-meter in the bird towed from a helicopter as a detector. The GREATEM system is considered to be an airborne version of the Long Offset Transient ElectroMagnetics (LOTEM) system (Strack, 1992). We developed a numerical forward modelling scheme using a staggered-grid finite-difference method (SFD, Fomenko and Mogi, 2002) adding a finite-length electrical dipole source routine. To construct a three dimensional (3D) resistivity model for GREATEM data, we have to overcome to compute a model composed of huge number of grid at wide frequency ranges because GREATEM has obtained resistivity data in time domain at a large number of sites. In order to verify the validity of the code, we compare the results with those obtained by the 2D numerical code of the LOTEM case developed by Mitsuhata (2000) for a 2D quarter space model and a trapezoidal hill model. Finally, we simulate GREATEM responses for 3D modeling with a conductor placed at coast-land boundary and a topography model.


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