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 ( ). We developed a numerical forward modelling scheme using a staggered-grid finite-difference method (SFD, ) 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 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.


Article metrics loading...

Loading full text...

Full text loading...


  1. Druskin, V., and L.Knizhnerman
    , 1994. Spectral approach to solving three-dimensional Maxwell’s diffusion equations in the time and frequency domains, Radio Sci., 29, 937–953.
    [Google Scholar]
  2. Femenko, E. and T.Mogi
    , 2002. A new computation method for a staggered grid of 3D EM field conservative modeling, Earth Planets and Space, 54, 499–509.
    [Google Scholar]
  3. Mitsuhata, Y.
    , 2000. 2-D electromagnetic modeling by finite-element method with a dipole source and topography, Geophysics, 65, 465–475.
    [Google Scholar]
  4. Mogi, T., K.Kusunoki, H.Kaieda, H.Ito, A.Jomori, N.Jomori, and Y.Yuuki
    , 2009. Grounded electrical source airborne transient electromagnetic (GREATEM) survey of Mount Bandai, northeastern Japan, Exploration Geophysics, 40, 1–7.
    [Google Scholar]
  5. Strack, K. M.
    , 1992. Exploration with Deep Transient Electromagnetics, Elsevier, pp. 373.
    [Google Scholar]
  6. Ward, S. H., and G. W.Hohmann
    , 1988, Electromagnetic theory for geophysical applications, Electromagnetic Methods in Applied Geophysics, SEG, 1, 130–311.
    [Google Scholar]

Data & Media loading...

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error