ELECTROMAGNETIC RADIATIONS ASSOCIATED WITH MAJOR EARTHQUAKES

Measurements of subsurface electric field changes have been conducted by means of borehole antennas. Changes in the number of pulse-like sig nals in a VLF band (seismic radio wave signals: SRS) evolved in close accordance with the occurrence of the earthquakes. The propagation of the long distance more than 500 km indicates the occurrence of wavegui de mode propagation between the ionosphere and the ground. The time ev olution of the number of the pulses indicates that there are two in th e SRS: one emitted directly from the epicentral area and the other, co ming induced by nonlinear interaction in the ionosphere, indirectly. T hese results indicate that the phenomena may be used to predict the ti me, location and magnitude of imminent earthquakes. Moreover, prominen t electromagnetic field changes are observed just at the time of the g reat earthquake providing clear evidence that the fault motion is acco mpanied by electromagnetic radiation. (C) 1998 Elsevier Science B.V.