LAUSR

Abstract The quantitative relationships between soil gas flux anomalies and faults systems in Agua Caliente-Tzitzio geothermal system were analyzed statistically. The main degassing features are related with thermal springs. The data used in the multivariate analysis are geothermal gas fluxes and spatial structural data (i.e., local fault strike). Exploratory Data Analysis (EDA) and Multivariate Analysis of Variance (MANOVA) were implemented, for the first time, to statistically describe the relation between the location of degassing features and the presence of some local fault systems, discriminating the direction of the main discharge channels and pointing to higher permeability faults. The results show that there is a statistically significant correlation between diffuse degassing of CO2 and CH4 and the N-S and E-W fault systems. Conversely, H2S degassing does not show any correlation with the fault systems, which may be related with the higher H2S reactivity compared with that of CO2 and CH4. It is highly recommended to use EDA and MANOVA techniques in order to establish the main degassing directions in geothermal and volcanic areas.