Multidisciplinary study of the “Salinelle" of Paternò mud volcanoes: characteristics of the fluids and possible correlations with Mt. Etna activity

Abstract

Monitoring of hydrothermal fluid emissions can provide detailed information about convective upwelling of geothermal fluids and their geochemical characteristics, as a function of tectonic stress or deeper gas input. In particular, at the Salinelle of Mt. Etna Geosite (Paternò and Belpasso, Eastern Sicily) natural emissions mainly consist of a fluid phase made of salty water, mud, gas and liquid hydrocarbons from an admixture of magmatic and hydrothermal gases. In this framework, our study mainly focused on the thermal and geochemical monitoring of hydrothermal fluids of the most active site, Salinelle dei Cappuccini. Nearby hydrothermal vents (Salinelle del Fiume; Salinelle di San Biagio), were also investigated. Analysis of the magnitude and frequency of seismic events all around Mt. Etna were conducted as well. Analysis of daily temperatures showed a constant trend: higher values (> 35° C) within the first monitoring period, followed by a strong decrease (down to 9° C), and a new gradual increase over the following months. This trend seems to be linked to magmatic processes occurring at depth below Mt. Etna, and could lead to a modification of the geochemical and thermal characteristics of the fluids issuing at the mud-pools and gas vents of Salinelle. The higher the frequency of seismic events corresponding to higher daily energy released, the higher fluid temperatures observed. Understanding how these fluids blend and what is their relationship with Mt. Etna volcanism can be of great importance in forecasting new eruptive cycles in the case they precede changes in volcanic activity.