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Theory of ground surface plasma wave associated with pre‐earthquake electrical charges
Author(s) -
Fujii Masafumi
Publication year - 2013
Publication title -
radio science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.371
H-Index - 84
eISSN - 1944-799X
pISSN - 0048-6604
DOI - 10.1029/2012rs005084
Subject(s) - surface wave , dispersion relation , wave propagation , physics , scattering , ground wave propagation , plasma , radio wave , electromagnetic electron wave , dispersion (optics) , ground plane , computational physics , geophysics , geology , optics , antenna (radio) , telecommunications , quantum mechanics , computer science
It is shown theoretically that if mobile electrical charge exists on the surface of the ground, a ground surface plasma wave is induced by radio waves. If the electrical charges are generated by tectonic stresses acting on crustal rocks prior to major earthquakes, the detection of a ground surface plasma wave could be used as a pre‐earthquake electromagnetic phenomenon. The ground surface plasma wave has a dispersion relation, i.e., the relation between frequency and wavelength, similar to that of the free‐space plane wave in the atmosphere over the radio broadcast frequency range. It allows for a strong coupling between these two types of waves. This is a mode of electromagnetic wave propagation that has not been previously reported. Numerical analysis demonstrates (1) the propagation of the ground surface plasma wave along a curved surface beyond the line of sight, (2) anomalous scattering by ground surface roughness, and (3) the generation of cross‐polarized waves due to the scattering. These results all agree well with radio wave anomalies observed before large earthquakes.