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Publications (50)
Volcanic CO2 diffuse degassing can impact infrastructure, soils, vegetation, microbiota, fauna, and human health. These impacts include acidification of soils, leading to sparse or absent vegetation and changes in microbiota types. Most of the study sites in this review are areas of quiescent volcanism, where soil CO2 emissions is a permanent and s...
Pululahua is a potentially active andesite and dacite lava dome complex. This paper presents the results of a survey focused on carbon dioxide (CO2) diffuse degassing at Pululahua, which was conducted during the 2017 International Association of Volcanology and Chemistry of the Earth's Interior (IAVCEI) Commission of the Chemistry of Volcanic Gases...
The Azores archipelago is located in the North Atlantic Ocean and is formed by nine volcanic islands. Present-day volcanic activity in the archipelago comprises not only seismic swarms and episodes of ground deformation in some volcanoes, but also hydrothermal gas manifestations. The main fumaroles are associated with central quiescent volcanoes an...
Carbon dioxide released permanently from soils in diffuse degassing areas may constitute a permanent hazard for the population. Several villages in the Azores archipelago (Portugal) are placed in areas with anomalous soil CO2 degassing and lethal indoor CO2 concentration (>10 vol%) has been already recorded in some buildings. The 2021-2022 dislodge...
The Ribeira Grande geothermal field is located on the northern flank of Fogo Volcano (S. Miguel Island, Azores) and it is characterised by the presence of several active hydrothermal manifestations. An analysis of the RG5 geothermal well has been carried out by the recognition of neoformation minerals with depth and the estimation of equilibrium te...
Substantial terrestrial gas emissions, such as carbon dioxide (CO2), are associated with active volcanoes and hydrothermal systems. However, while fundamental for the prediction of future activity, it remains difficult so far to determine the depth of the gas sources. Here we show how the combined measurement of CO2 and radon-222 fluxes at the surf...
A set of springs were sampled along São Miguel Island (Azores, Portugal) to proceed to the characterization of the major-ion and radon (222Rn) content. According to the selection criteria a total of 42 discharges were sampled, both during winter and summer periods, along major geological units, namely 3 springs at Sete Cidades Volcano, 4 at Nordest...
Sites with naturally high CO2 conditions provide unique opportunities to forecast the vulnerability of coastal ecosystems to ocean acidification, by studying the biological responses and potential adaptations to this increased environmental variability. In this study, we investigated the bivalve Ervilia castanea in coastal sandy sediments at refere...
Quantification of the CO2 released by the volcanoes to the atmosphere is relevant for the evaluation of the balance between deep-derived, biogenic and anthropogenic contributions. The current study estimates the CO2 released from Furnas do Enxofre degassing area (Terceira Island, Azores archipelago) by applying an approach that integrates the flux...
Chemical and isotopic vertical profiles from the volcanic lakes of Sete Cidades, Santiago, Fogo, Congro and Furnas (Island of São Miguel, Azores Archipelago, Portugal) were studied to investigate the biogeochemical processes acting at different depths, with a focus on the CO2 and CH4 dynamics. These lakes are fed by meteoric water affected by seawa...
doi: 10.7185/geochemlet.1920 Abiotic formation of n-alkane hydrocarbons has been postulated to occur within Earth's crust. Apparent evidence was primarily based on uncommon carbon and hydrogen isotope distribution patterns that set methane and its higher chain homologues apart from biotic isotopic compositions associated with microbial production a...
Nowadays volcanic manifestations in the Azores archipelago are represented by several permanent gas emissions that include hydrothermal fumaroles, thermal and cold CO2-rich springs, as well as diffuse degassing areas. Visible manifestations of volcanism are found out in most of the islands and their isotopic imprints give clues both to understand t...
Santiago and Congro are two maar crater lakes, located at São Miguel, the largest island of the Azores archipelago. Santiago Lake is located on the Sete Cidades Volcano, at an altitude of 364 m, presenting a surface area of 0.25 km² and a maximum depth of 33 m. Congro Lake is located on the Congro Fissural Volcanic System, at an altitude of 420 m,...
Monitoring soil CO2 diffuse degassing areas has become more relevant in the last decades to understand seismic and/or volcanic activity. These studies are specially valuable for volcanic areas without visible manifestations of volcanism, such as fumaroles or thermal springs. The development and installation of permanent soil CO2 flux instruments ha...
Hydrothermal areas are potentially hazardous to humans as volcanic gases such as radon ((222)Rn) are continuously released from soil diffuse degassing. Exposure to radon is estimated to be the second leading cause of lung cancer, but little is known about radon health-associated risks in hydrothermal regions. This cross-sectional study was designed...
Chemical and isotopic vertical profiles from the volcanic lakes of Sete Cidades, Santiago, Fogo, Congro and Furnas (Island of São Miguel, Azores Archipelago, Portugal) were studied to investigate the biogeochemical processes acting at different depths, with a focus on the CO2 and CH4 dynamics. These lakes are fed by meteoric water affected by seawa...
Recent geophysical evidence for large-scale regional crustal inflation and localized crustal magma intrusion has made Lastarria volcano (northern Chile) the target of numerous geological, geophysical, and geochemical studies. The chemical composition of volcanic gases sampled during discrete campaigns from Lastarria volcano indicated a well-develop...
VOLRISKMAC: Strengthening R&D&I capacities for the monitoring of volcanic activity in Macaronesia, is a project financed by the Cooperation Program INTERREG V-A Spain-Portugal MAC (Madeira-Azores-Canaries) 2014-2020. This Program is the main instrument available to the outermost regions of Spain and Portugal to offer an effective response to the co...
VOLRISKMAC (MAC/3.5b/124) is a project financed by the Interreg Madeira-Azores-Canarias (MAC) 2014-2020 Territorial Cooperation Program-Axis 3-Promote adaptation to climate change and risk prevention and management. The main objective of the project VOLRISKMAC is to strengthen capacities for the monitoring of volcanic activity, with the aim of impr...
Gaseous elemental mercury (Hg⁰g or GEM) and CO2 are emitted from active hydrothermal systems in volcanic areas mostly through diffuse degassing. Here, data from about 400 simultaneous measurements of soil GEM and CO2 flux performed within the caldera of Furnas Volcano, São Miguel Island (Azores) are discussed for the first time. This survey aimed a...
Electrical conductivity tomography is a well-established galvanometric method for imaging the subsurface electrical conductivity distribution. We characterize the conductivity distribution of a set of volcanic structures that are different in terms of activity and morphology. For that purpose, we developed a large-scale inversion code named ECT-3D...
Accurate geophysical imaging of shallow subsurface features provides crucial constraints on understanding the dynamics of volcanic systems. At Furnas Volcano (Azores), intense circulation of volcanic fluids at depth leading to high CO2 outgassing and flank destabilisation poses considerable threat to the local population. Presented is a novel 3-D e...
Sao Miguel Island (Azores Archipelago, Portugal) hosts five volcanic lakes: Sete Cidades, Santiago, Fogo, Congro and Furnas. Due to their peculiar thermal characteristics, they can be defined as atelomictic with partial stratification and destratification on a daily basis. This thermal regime is peculiar of tropical lakes and can influence lake fun...
The Azores archipelago is composed of nine volcanic islands located at the triple junction between the North American, Eurasian, and Nubian plates. Nowadays the volcanic activity in the archipelago is characterized by the presence of secondary manifestations of volcanism, such as hydrothermal fumaroles, thermal and cold CO2-rich springs as well as...
Carbon dioxide is one of the main soil gases released silently and permanently in diffuse degassing areas, both in volcanic and non-volcanic zones. In the volcanic islands of the Azores (Portugal) several villages are located over diffuse degassing areas. Lethal indoor CO2 concentrations (higher than 10 vol %) were measured in a shelter located at...
Three-Dimensional Audio-Magnetotelluric Imaging of the Furnas Caldera and Hydrothermal Area (Azores Archipelago, Portugal)
A study on diffuse CO2 degassing was undertaken at Furnas lake (São Miguel island, Azores) in order to estimate the total diffuse CO2 output and identify anomalous degassing areas over the lake. Furnas lake is located in Furnas Volcano, the easternmost of the three active central volcanoes of São Miguel island. The lake has an area of 1.87 km2 and...
Furnas Caldera Volcanic Complex, Sao Miguel Island (Azores), last erupted in 1630 and is famous for its intense hydrother-mal activity (i.e. fumarolic fields, thermal springs, cold CO2-rich mineral waters and diffuse CO2 soil emanations), which directly affect the villages of Furnas and Ribeira Quente. Here we report the first systematic investigat...
Eight years of permanent soil CO2 diffuse degassing monitoring at Furnas and Fogo volcanoes shows that several environmental variables may influence soil CO2 flux to a different extent depending on the location. Stepwise multivariate regression analysis applied to the data acquired by the permanent flux stations installed on São Miguel showed that...
Soil CO2 diffuse degassing constitutes a permanent risk in quiescent volcanic-hydrothermal areas, as is the case in the Azores archipelago. Since the early 1990s geochemical studies carried out in São Miguel Island showed that some villages are placed in anomalous high degassing areas, and indoor measurements performed in various dwellings highligh...
A soil 222Rn continuous monitoring test was performed in three sampling points inside Furnas Volcano caldera and 222Rn concentration varied between 0 and 153000 Bq/m3. Multivariate regression and spectral analyses were applied to the time series registered in order to understand and filter the influence of external factors on soil 222Rn concentrati...
Time series of soil CO2 efflux recorded in the Azores archipelago volcanic-hydrothermal areas feature daily and seasonal variations. The recorded CO2 efflux values were lower during summer than in the winter season. The diurnal CO2 efflux values were higher at dawn and lower in the early afternoon, contrary to that observed in biogenic environments...
The occurrence and geochemistry of mineral water discharges in the Azores (Portugal) have been studied. Due to the volcanic nature of the archipelago, mineral water discharges occur in seven of the nine islands, namely at São Miguel, Terceira, São Jorge, Pico, Faial, Graciosa and Flores, both associated to perched-water and basal aquifers, and main...
Furnas volcano is a polygenetic trachytic volcanic centre with caldera that shows secondary manifestations of volcanism, as recognized by the presence of fumarolic grounds, thermal springs, CO2-rich mineral waters and several soil diffuse degassing areas of carbon dioxide (CO2) and radon (222Rn). Radon is a radioactive gas that can be a potential t...
The preliminary evaluation of radon levels registered in a building at Ponta Delgada city, São Miguel Island, comprises soil diffuse degassing characterization and indoor air quality analysis. Radon and carbon dioxide (CO2) concentration as well as soil temperature measurements were performed to characterize the soil diffuse degassing emissions in...
Furnas Volcano is a dormant central volcano located in the eastern part of São Miguel Island (Azores archipelago, Portugal). The last volcanic eruption in this volcanic system took place in 1630 causing about 200 victims. Present-day activity comprises fumarolic fields, thermal and cold CO<sub align="right"> 2 </sub>-rich springs and soil diffuse d...
In volcanic areas, where the sedimentation rates are higher than fault-slip rate, neotectonic surveys are even
more difficult due to topography mantling by thick and non cohesive recent fall deposits preventing the surface
expression recognition of tectonic structures by traditional field works. In Azores Archipelago adding to this
limitation is th...
Carbon dioxide (CO2) diffuse degassing structures (DDS) at Furnas Volcano (São Miguel Island, Azores) are mostly associated with the main fumarolic fields, evidence that CO2 soil degassing is the surface expression of rising steam from the hydrothermal system. Locations with anomalous CO2 flux are mainly controlled by tectonic structures oriented W...
Furnas volcano is one of the three quiescent central volcanoes of São Miguel Island (Azores Archipelago, Portugal). Its present activity is marked by several degassing manifestations, including fumarolic fields, thermal and cold CO2 springs and soil diffuse degassing areas. One of the most important soil diffuse degassing areas extends below Furnas...
Since October 2001, four soil CO2 flux stations were installed in the island of São Miguel (Azores archipelago), at Fogo and Furnas quiescent central volcanoes. These stations perform measurements by the accumulation chamber method and, as the gas flux may be influenced by external variables, the stations are equipped with several meteorological se...
A detailed study was carried out on a piece of land that had been struck by lightning during the violent rainstorm that raged
over the Island of São Miguel (Azores Archipelago) in late October 2006. Temperature and gas measurements (CO2, CO, H2S and CH4) were performed in four study trenches, dug in an area of ∼3m2, where an underground fire had be...
Furnas Volcano is one of the three active central volcanoes of S. Miguel Island, in the Azores Archipelago. Fumarole grounds, thermal springs, CO2 rich mineral cold waters and several soil diffuse degassing areas are the main secondary volcanic phenomena that can be seen at Furnas Volcano surface. Radon can be an important indicator of deep events...
