MODELING THE EARTH'S PROPAGATION behavior at extremely low frequencies (ELFs) is an effective method for developing a three-dimensional geodesic grid of the Earth-ionosphere cavity for the purposes of studying electromagnetic (EM) precursors to major earthquakes and remote sensing of major oil deposits. Jamesina Simpson, a student member of the IEEE, and Allen Taflove of the Electrical Engineering and Computer Science Department at the McCormick School of Engineering at Northwestern University (Evanston, IL) and Ross Heikes with the Department of Atmospheric Science at Colorado State University (Fort Collins, CO) pursued a three-dimensional, finite-difference time-domain (FDTD) study of ELF EM propagation within the entire Earth-ionosphere cavity in order to map inhomogeneities and anisotropies of EM excitiations throughout the ionosphere, lithosphere,-oceans, and land masses for a better understanding of ELF propagation by using a geodesic lattice arrangement.
One of the examples reported by the researchers using their new approach is a new ELF radar for major oil deposits. The system is based on a powerful ELF radar antenna and two separate FDTD models to calculate the time waveforms of the magnetic components of high-power transmitted waveforms. According to their calculations, the technique could be used to detect the presence of oil depositions buried as deep as 10 to 20 km beneath the Earth's surface. See "FDTD Modeling of a Novel ELF Radar for Major Oil Deposits Using a Three-Dimensional Geodesic Grid of the Earth-Ionosphere Waveguide," IEEE Transactions on Antennas and Propagation, June 2006, Vol. 54, No. 6, p. 1734.