ANOMALIES IN GEOPHYSICAL AND GEOCHEMICAL PARAMETERS REVEALED ON THE OCCASION OF THE PARAVANI (M = 5.6) AND SPITAK (M = 6.9) EARTHQUAKES (CAUCASUS)

On the occasion of the Paravani (May 13, 1986) and Spitak (December 7, 1988) earthquakes, which occurred in the Caucasus, irregularities in several geophysical and geochemical parameters were revealed. In this paper, data on anomalies in the water level in deep wells, in the helium content in thermal waters, in electromagnetic signals revealed by surface and underground antennae, and in an F(sigma(tau)) function based on traveltimes of P and S waves, are presented. Data were collected from sites located in the Georgian S.S.R. In the case of the Spitak earthquake, the anomalies in all the presented parameters can be attributed to the processes that preceded and accompanied the earthquake. For the Paravani earthquake, no significant precursory phase seems to have been reflected in the helium content in thermal waters, though this phase can be observed in the other parameters. In general, it would appear that the magnitude of the earthquake and the distance from the epicentre exert a significant control on the appearance of the anomalies.