Seismic electromagnetic signals (SEMS) explained by a simulation experiment using electromagnetic waves

The propagation characteristics of seismic electromagnetic signals (SEMS) both at an ultra low frequency (ULF) and at a very low frequency (VLF) are discussed based on a model experiment of propagation of electromagnetic (EM) waves in the earth's crust and atmospheric waveguide. A granite slab and two aluminium plates simulated the earth's crust, ionosphere and underground conductive layer, respectively. The Greek archipelago was modeled using a geographical map with the ocean covered by aluminium foil. The intensity of EM waves transmitted from a model hypocenter was mapped to investigate the influence of the ocean. The propagation of VLF waves over the long distance was obtained, while that of ULF indicated the exponential decay from the epicenter. This experiment considered waveguides might explain the ocean's effect on the selectivity and the long distance propagation of SEMS, presumably including seismic electric signals (SES) in the VAN method. (C) 1998 Elsevier Science B.V. All rights reserved.