A wide data set of groundwater helium content collected in the Caucasus from 1985 to 1991 has been analyzed. The strongest earthquakes that occurred in this area during the helium measurement period were the: Paravani (May 13th, 1986, M=5.6), Spitak (December 7th, 1988, M=6.9) and Georgian (April 29th, 1991, M=6.9) earthquakes. The analysis of the helium content data revealed statistically significant increases in this parameter on the occasion of the Paravani and Spitak earthquakes and no increase on the occasion of the Georgian earthquake. These results corroborate those obtained by the analysis of scanty helium content data presented in previous papers. With the exception of the anomalous increases, the helium content data were subjected to randomness tests and spectral analysis and cross correlation with meteorological parameters and areal seismicity were also attempted. The main result obtained is that the destructive Spitak earthquake produced some statistical changes in the groundwater helium content fluctuations some years before and after its occurrence.
Bella, F., Biagi, P.f., Caputo, M., Cozzi, E., DELLA MONICA, G., Ermini, A., et al. (1995). Helium content in thermal waters in the Caucasus from 1985 to 1991 and correlations with the seismic activity. TECTONOPHYSICS, 246(4), 263-278 [10.1016/0040-1951(94)00260-G].