DETAILED RADON ISOTOPE MEASUREMENTS IN NI SSYROS AND SUSAKI GEOTHERMAL FIELDS, GREECE

Two groups of Radon isotope measurements were carried out, in the geot hermal regions of the Nissyros Caldera and the Susaki geothermal field . The radon emission observed in Susaki is less than 3,720 Bq/m(3) and in Nissyros Island about 36 x 10(3) Bq/m(3). The observed difference in the emission level of these isotopes was explained by the differenc e in the lithology and geothermal activity prevailing in Nissyros Cald era and Susaki areas. The contouring distribution of radon and thoron in these areas was correlated with the complicated geology of these tw o geothermal fields and interesting features were observed regarding l ocation and direction of faults.