The volcanic activity changes occurred in the 2021-2022 at Vulcano island (Italy), inferred by the abrupt variations of soil CO2 output

The active cone of La Fossa is a close conduit volcano characterized by solphataric activity, manifested by discharging fluids through fumaroles and soil degassing. Since 1978 several degassing crises have been observed and interpreted as early signals of volcanic unrests. Recently, from June 2021 to May 2022, we measured the changes in soils CO₂ release to evaluating the level and duration of the actual exhaling crises. The CO₂ output has been evaluated by surveys carried out in anomalously degassing areas, located both in the La Fossa cone summit area and in other peripheral zones, coupled to near-real time monitoring data acquired by three automated stations. The strong and deep input of volatiles released from an underlying magma batch modified the chemical composition of the shallow plumbing system, bringing the system to a higher level of CO₂ total pressure. This work highlights that a geochemical networks of stations, located at some distance from the fumaroles release and/or from eruptive conduits, is useful and can be applied to characterizing and monitoring any other active volcanic system. This type of studies can be useful to contribute to forecast the next evolution of the studied systems.

Carbon isotopic signature of interstitial soil gases reveals the potential role of ecosystems in mitigating geogenic greenhouse gas emissions: Case studies from hydrothermal systems in Italy

Volcanic and hydrothermal areas largely contribute to the natural emission of greenhouse gases to the atmosphere, although large uncertainties in estimating their global output still remain. Nevertheless, CO₂ and CH₄ discharged from hydrothermal fluid reservoirs may support active soil microbial communities. Such secondary processes can control and reduce the flux of these gases to the atmosphere. In order to evaluate the effects deriving from the presence of microbial activity, chemical and carbon (in CO₂ and CH₄) isotopic composition of interstitial soil gases, as well as diffuse CO₂ fluxes, of three hydrothermal systems from Italy were investigated, i.e. (i) Solfatara crater (Campi Flegrei), (ii) Monterotondo Marittimo (Larderello geothermal field) and (iii) Baia di Levante in Vulcano Island (Aeolian Archipelago), where soil CO₂ fluxes up to 2400, 1920 and 346 g m^-2 day^-1 were measured, respectively. Despite the large supply of hydrothermal fluids, ¹³CO₂ enrichments were observed in interstitial soil gases with respect to the fumarolic gas discharges, pointing to the occurrence of autotrophic CO₂ fixation processes during the migration of deep-sourced fluids towards the soil-air interface. On the other hand, (i) the δ¹³C-CH₄ values (up to ~48‰ vs. V-PDB higher than those measured at the fumarolic emissions) of the interstitial soil gases and (ii) the comparison of the CO₂/CH₄ ratios between soil gases and fumarolic emissions suggested that the deep-sourced CH₄ was partly consumed by methanotrophic activity, as supported by isotope fractionation modeling. These findings confirmed the key role that methanotrophs play in mitigating the release of geogenic greenhouse gases from volcanic and hydrothermal environments.

Analysis of Thermal Anomalies in Volcanic Areas Using Multiscale and Multitemporal Monitoring: Vulcano Island Test Case

Surface temperatures derived by 208 ASTER and L8 satellite imagery were analysed to test multiscale and multitemporal capability through available sets of thermal data to support the volcanic monitoring of Vulcano Island in Italy. The analysis of thermal historical series derived by ASTER and L8 shows that two are the main thermally active areas: La Fossa crater and the mud pool of Fangaia. In this work we aimed to assess the correlation between the satellite-retrieved temperatures with those measured during the daytime ground field campaign conducted within the same time period and, in particular cases, simultaneously. Moreover, nighttime data acquired by an airborne and field campaign were processed with the same methodology applied to satellite data for a multiscale approach verification. Historical meteorological data acquired from a weather station were also considered. Statistically significant correlations were observed between nighttime acquisitions and meteorological data. Correlations were also significant for temperature measured during the airborne campaign, while differences up to 50% with daytime acquisition during the ground field campaigns were observed. The analysis of the results suggests that within nighttime data acquisition, differences between satellite-derived temperatures and ground temperature measurements are considerably reduced; therefore nighttime data acquisition is recommended to detect thermal anomalies.