Estimation of electric fields in the conducting Earth's crust for oscillating electric current dipole sources and implications for anomalous electric fields associated with earthquakes

概要

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Electromagnetic radiation possibly associated with earthquake occurrences in the Earth's crust can be treated as a problem of electromagnetic induction within a conducting half-space representing the crust. We estimated the magnitude of the electric field near the Earth's surface for oscillating electric current dipole sources located at various depths. It then turned out that the electric field highly attenuates, as expected, and the source must be stronger than 10^5 Am, even if it is located at a depth of several kilometers, for practically detecting signals at frequencies in the ULF range. We also examined the electric field near the Earth's surface for a box-car type source in uniform and non-uniform crust models. We found that the wave form of the source is rather well preserved in both models but signal amplitudes are very small and unlikely to be drastically enhanced even in a non-uniform crustal structure, although this discussion is based only on a specific non-uniform model.
独立行政法人防災科学技術研究所の論文
1993-03-29