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Bonfanti, Pietro
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Bonfanti, Pietro
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pietro.bonfanti@ingv.it
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staff
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7003513480
30 results
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- PublicationRestrictedPreliminary investigation on soil CO2 and soil CH4 effluxes from a geothermal area near Palagonia (Sicily, Italy)(2012-09)
; ; ; ; ; ; ; ; ;Giammanco, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Bonfanti, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Carapezza, M. L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Pagliuca, N.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Quattrocchi, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Ricci, T.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Sciarra, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Spampinato, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; ; ; ; ; ; ; The central part of eastern Sicily is characterized by several areas of strong crustal degassing. These gases are mostly carbon dioxide and methane and are particularly concentrated in some focused emissions (gas vents, mud volcanoes) or as diffuse degassing along major faults. In this study, the extent and orientation of soil CO2 and soil CH4 effluxes were investigated on a wide area (about 40 km2) located about 50 km southwest of Mt. Etna (Fig. 1). From a structural point of view, this area lays on a typical foredeep - foreland system that marks the boundary between the southern part of the Eurasian plate and the northern part of the African plate in the central Mediterranean. The situation was further complicated by the tectonic subsidence of the foredeep to the north of the northern Hyblean margin (YELLIN-DROR et alii, 1997; CARBONE et al., 1982) and the formation of a series of ENE-WSW oriented grabens and horsts, the Lentini Graben being the most important of these structures. This area was characterized by both submarine and subaerial volcanism until 1.7-2 Ma (BARBERI et alii, 1974; GRASSO et alii, 1983; GURENKO AND SCHMINCKE, 2002; SCHMINCKE et alii, 1997; TRUA et alii, 1997), and it was affected by strong seismicity in historical times. The surface geology consists of recent alluvial deposits and Plio-Pleistocene clays and sands interbedded with coeval basaltic lavas and pyroclastics of alkaline affinity (CARBONE et alii, 1987). Strong gas emissions in this area have been known since pre-Greek times, as reported by FERRARA (1805). PONTE (1919, 1934) showed that the gas that erupted through Naftìa Lake (located just southwest of the village of Palagonia, see Fig. 1) was pure carbon dioxide and calculated total emissions at about 80,000 t d-1. Today, the main gas emission is exploited for commercial use (Mofeta dei Palici plant, CO2 output estimated as about 250 t d-1, R. Romano pers. comm., 1998). The area is also characterized by several water well with warm (20-50 °C) water. Recent geochemical studies on this area (DE GREGORIO et alii, 2002; CARACAUSI et alii, 2003a, 2003b; GIAMMANCO et alii, 2007) showed that anomalous CO2 degassing has a hydrothermal or magmatic origin and it is linked to the dynamics of Mt. Etna’s plumbing system.1151 76 - PublicationRestrictedLong-term (1997-2007) geochemical monitoring of gases from the Umbria-Marche region(2009-10-15)
; ; ; ; ;Italiano, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia ;Martinelli, G.; ARPA Environmental Protection Agency of Emilia Romagna ;Bonfanti, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia ;Caracausi, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia; ; ; The paper presents the results of ten-year long geochemical monitoring carried out in the area hit by the 1997–98 Umbria–Marche seismic sequence (Northern Apennines, Italy) showing the advancement in our understanding of the reciprocal relationships between fluids and tectonic structures in this area. Long-term geochemical monitoring has allowed us to define the geochemical features of the gas phase and to model its origins and interactions. All the released gases, including dissolved and venting gases, have predominantly crustal origin and have suffered from substantial modifications in their geochemical features. The whole seismogenic process is considered to be responsible for the modifications recorded over a wide time interval, including the production of CO2 from mechanical stress on carbonate rocks. We interpret the modifications occurred to the gas phase during the 1997–98 period as related to faulting activity, while those recorded after the end of the seismic crisis are interpreted as being a consequence of the crustal relaxation. The data show that it is almost impossible to interpret the temporal variation without coupling long-term geochemical monitoring and knowledge of the genetic features of the fluids. Therefore the information coming from the circulating fluids is a powerful tool to better understand the physical processes governing the faulting activity.821 27 - PublicationRestrictedCluster analysis of soil CO2 data from Mt. Etna (Italy) reveals volcanic influences on temporal and spatial patterns of degassing(2009)
; ; ;Giammanco, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Bonfanti, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia; Soil CO2 concentration data were collected periodically from July 2001 to June 2005 from sampling site grids in two areas located on the lower flanks of Mt. Etna volcano (Paternò and Zafferana Etnea–Santa Venerina). Cluster analysis was performed on the acquired data in order to identify possible groups of sites where soil degassing could be fed by different sources. In both areas three clusters were recognised, whose average CO2 concentration values throughout the whole study period remained significantly different from one another. The clusters with the lowest CO2 concentrations showed timeaveraged values ranging from 980 to 1,170 ppm vol, whereas those with intermediate CO2 concentrations showed time-averaged values ranging from 1,400 to 2,320 ppm vol, and those with the highest concentrations showed time-averaged values between 1,960 and 55,430 ppm vol. We attribute the lowest CO2 concentrations largely to a biogenic source of CO2. Conversely, the highest CO2 concentrations are attributed to a magmatic source, whereas the intermediate values are due to a variable mixing of the two sources described above. The spatial distribution of the CO2 values related to the magmatic source define a clear direction of anomalous degassing in the Zafferana Etnea–Santa Venerina area, which we attribute to the presence of a hidden fault, whereas in the Paternò area no such oriented anomalies were observed, probably because of the lower permeability of local soil. Time-series analysis shows that most of the variations observed in the soil CO2 data from both areas were related to changes in the volcanic activity of Mt. Etna. Seasonal influences were only observed in the time patterns of the clusters characterised by low CO2 concentrations, and no significant interdependence was found between soil CO2 concentrations and meteorological parameters. The largest observed temporal anomalies are interpreted as release of CO2 from magma batches that migrated from deeper to shallower portions of Etna’s feeder system. The pattern of occurrence of such episodes of anomalous gas release during the observation period was quite different between the two studied areas. This pattern highlighted an evident change in the mechanism of magma transport and storage within the volcano’s feeder system after June 2003, interpreted as magma accumulation into a shallow (<8 km depth) reservoir.767 27 - PublicationOpen AccessEvidence of Tectonic Control on the Geochemical Features of the Volatiles Vented along the Nebrodi-Peloritani Mts (Southern Apennine Chain, Italy)(2019)
; ; ; ; ; Investigations carried out over the southernmost portion of the Apennine chain (Nebrodi-Peloritani Mountains, Sicily, Italy) reveal a close connection between the tectonic setting and the regional degassing of CO2-dominated volatiles. The geochemical features of the collected gases show that the pristine composition has been modified by gas-water interaction (GWI) and degassing processes. The 3He/4He isotopic ratio in the range of 0.7-2.8 Ra highlights variable contributions of mantle-derived helium, representing an unusual feature for the crustal regime of the study areas characterized by the widespread presence of 4He-producer metamorphic rocks. The degassing of mantle helium is coherent with the tectonics and related to the NW-SE extensional regime of the Calabro-Peloritan Arc (CPA). We propose that the degassing regime as well as the geochemical features of both the dissolved and bubbling gases is closely connected to the strain accumulation rate, inducing almost no temporal changes and insignificant deep-originated fluid contributions to the locked fault volumes. Investigations including discrete and continuous monitoring and degassing-rate estimations are useful tools to gain a better insight into the evolution of seismogenesis, considering the fault rupture as the final stage of a seismic cycle.704 22 - PublicationOpen AccessTracing Magma Migration at Mt. Etna Volcano during 2006–2020, Coupling Remote Sensing of Crater Gas Emissions and Ground Measurement of Soil Gases(2024)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; The geochemical monitoring of volcanic activity today relies largely on remote sensing, but the combination of this approach together with soil gas monitoring, using the appropriate parameters, is still not widely used. The main purpose of this study was to correlate data from crater gas emissions with flank emissions of soil gases at Mt. Etna volcano from June 2006 to December 2020. Crater SO2 fluxes were measured from fixed stations around the volcano using the DOAS technique and applying a modeled clear-sky spectrum. The SO2/HCl ratio in the crater plume was measured with the OP-FTIR technique from a transportable instrument, using the sun as an IR source. Soil CO2 efflux coupled with the 220Rn/222Rn activity ratio in soil gases (named SGDI) were measured at a fixed monitoring site on the east flank of Etna. All signals acquired were subject both to spectral analysis and to filtering of the periodic signals discovered. All filtered signals revealed changes that were nicely correlated both with other geophysical signals and with volcanic eruptions during the study period. Time lags between parameters were explained in terms of different modes of magma migration and storage inside the volcano before eruptions. A comprehensive dynamic degassing model is presented that allows for a better understanding of magma dynamics in an open-conduit volcano.186 12 - PublicationOpen AccessRELAZIONI TRA FLUIDI CIRCOLANTI E TETTONICA ATTIVA NEL SETTORE MERIDIONALE DELL’ARCO CALABRO: UNO STRUMENTO PER LA VALUTAZIONE DEI PROCESSI SISMOGENETICI(2008-12-10)
; ; ; ;Italiano, Francesco; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia ;Bonfanti, Pietro; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia ;Maugeri, Roberto; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia; ; ; ; ; ; ;Di Bucci, Daniela; DPC ;Neri, Giancarlo; Univ. Messina ;Valensise, Gianluca; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; ; Le metodologie di indagine geochimica applicate ad un’ampia porzione dell’Appennino meridionale, esteso dalla Calabria settentrionale ai Monti Nebrodi, nell’ambito del progetto INGV-DPC S2, hanno consentito di valutare le caratteristiche dei fluidi emessi in coincidenza di importanti lineamenti strutturali, permettendo di evidenziare le relazioni intercorrenti tra l’assetto tettonico e la genesi, la circolazione ed il comportamento dei fluidi circolanti. L’area di studio rappresenta la porzione più meridionale dell’Arco Calabro, il cui stile deformativo dominante dal Pleistocene medio all’attuale, è caratterizzato da una estensione ESE-WNW. Nella Sicilia nord-orientale, le faglie neotettoniche dislocano i livelli crostali più superficiali e si dispongono secondo direzioni preferenziali orientati circa NW-SE con meccanismi deformativi a componente trascorrente ed estensionale e N-S/NE-SO con meccanismi deformativi trascorrenti, a tratti con componente compressiva. Le strutture crostali radicate sono rappresentate dal sistema “Patti-Eolie”, che si connette a terra con il sistema “Tindari-Letojanni” e dal “sistema di Messina”. Il primo mostra, anche a livello sismologico, caratteri deformativi transtensivi; nel secondo sistema, caratterizzato da faglie a prevalente componente distensiva del rigetto la catena presenta un tasso di sollevamento recente non uniforme, con valori massimi lungo la costa messinese ionica e tassi minori lungo quella tirrenica. L’esistenza di fenomeni attivi di sollevamento regionale è dimostrato da alcune evidenze, come la presenza di argille marine quaternarie affioranti diverse centinaia di metri al di sopra del livello del mare nonché di piattaforme di abrasione tirreniane ben sviluppate ad una altitudine di circa 130 m. nei pressi di Taormina e sul versante calabrese dello stretto di Messina. La struttura tettonica più importante che interseca il sistema Ibleo-Maltese è costituito dal sistema di faglie di Messina, orientato NNE-NNW. Il terremoto di Messina del 1908 è stato attribuito ad una “faglia cieca” nell’area di Messina. Lungo le principali strutture tettoniche, sono presenti attività idrotermali e di degassamento note da tempi storici, che dal punto di vista geochimico mostrano caratteristiche molto diverse in funzione della loro ubicazione.210 291 - PublicationRestrictedCoupling geochemical and geophysical signatures to constrain strain changes along thrust faults(2012-03)
; ; ; ; ; ; ; ; ;Petrini, R.; Dipartimento di Geoscienze, Università di Trieste ;Italiano, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia ;Riggio, A.; Ist. Naz. Oceanografia e Geofisica Sperimentale, Trieste ;Slejko, F.F.; Dipartimento di Geoscienze, Università di Trieste ;Santulin, M.; Ist. Naz. Oceanografia e Geofisica Sperimentale, Trieste ;Buccianti, A.; Dipartimento di Scienze della Terra, Università di Firenze ;Bonfanti, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia ;Slejko, D.; Ist. Naz. Oceanografia e Geofisica Sperimentale, Trieste; ; ; ; ; ; ; Anomalous geochemical signals inferred from elemental and isotopic analyses on spring waters and soil degassing are often detected in response to tectonic loading along faults. Recent results highlighted how the geochemical anomalies are closely related to episodes of crustal deformation. In the present study, the carbon dioxide and radon from soil degassing and the geochemical features of springs spatially related to fault zones in the Friuli-Venezia Giulia region (north-eastern Italy), a seismic-prone area, have been coupled with crustal deformation analyses to better define the possible correlations between fluctuations of geochemical parameters and seismicity, with the aim of gaining new information about local geodynamic processes. The natural CO2 and Rn degassing was evaluated by a soil gas survey carried out by a grid of about 100 measuring sites located over the area that had been hit by strong earthquakes, in the past (Gemona – Idrija 1511, Raveo 1700, Tolmezzo 1788 and 1928, Gemona 1976). The results obtained show a significant amount of crustal-originated gases, especially CO2, possibly related to decarbonation reactions and stress accumulation occurring in deep-seated structures. The spring waters show, in some cases, anomalous geochemical transients, in particular concerning the chloride and Rn concentration, that are not related to seasonal changes and interpreted to reflect distinct fluid pressure regimes within the fault zone, yielding the leakage of pore fluids into the country-rock aquifers. In particular, the changes in the chloride content have been tentatively modeled in terms of pore-fluid expulsion from compacting clays during pressure gradients at shallow crustal levels. The flow regimes and chemical evolution have been related to the strain computed at the outlet sites through the Gutenberg–Richter relation parameters and the regional value of the strain rate. The information provided here may be used to start up a long-term geochemical monitoring of this seismically active area able to detect the modifications occurring in the circulating fluids to gain a better insight on the relationships between the geochemistry of the fluids and the activity of the local seismogenic faults.941 24 - PublicationOpen AccessHydrological versus volcanic processes affecting fluid circulation at Mt. Etna: Inferences from 10 years of observations at the volcanic aquifer(2017-01-10)
; ; ; ; ; ; ; ; ; ; ; The time series of geochemical data available for the network ofwells and drainage galleries atMt. Etna has been analyzed to identify the changes in water chemistry related to the input of volcanic CO2 and those related to hydrogeological dynamics. The dynamics of hydrological systems is mainly affected by changes in the rainfall, since this influences the yields of both springs and drainage galleries and the height of thewater table of unconfined aquifers. In addition, the characteristics of hydrological systems can change with the fluid pressure. These mechanisms are probably enhanced by changes in the crustal strain,which can cause interbasin transfer ofwater. The changes in water circulation are paralleled by variations in physicochemical characteristics of groundwater, since water transfer probably occurs among water bodies with different temperatures and compositions. Based on the abovemechanisms, the contribution of different water types has been estimated according to their chemical composition: it has been assumed that water circulating in the volcanic pile has a typical HCO3 −-rich composition,whereas Cl−, SO4 =, andNO3 − could be contributed by rainfall, anthropogenic pollution, and sedimentary fluids rich in Na+ and Cl−. The compositionally different endmembers have been identified based on the results of factor analysis,which allowed those chemicals accounted for by a singlewater endmember to be grouped within the same factor. In some cases the SO4 = enrichment is related to the dissolution of SO4 =-bearing alteration minerals contained in volcanic sequences, and in such cases this is associated with HCO3 −. We hypothesize a binary mixing between the HCO3 −-rich volcanic end member and an end member pollutedwith Cl−, SO4 =, andNO3 − related to water circulation at shallow levels. These two end members are identified by their HCO3 −/(Cl−+SO4 = +NO3 −) ratio and Cl−, SO4 =, and NO3 − contents measured at each sampling site. The extent of mixing between these different water types changes over time, probably due to changes in their circulation patterns, with water being transferred from/towater bodieswith different compositions. Once the proportion of the HCO3 − content related to the binary mixing is determined, we can compute the amount of HCO3 − related to the variable input of CO2 over time into the aquifer. The obtained temporal trends are—over a long time period—synchronous in the two sectors of the volcanowhere themaximal CO2 degassing occurs, namely the Paternò-Belpasso area on the southwestern flank and the Zafferana-S. Venerina area on the eastern flank. This provides evidence for a common deepmechanism underlying the CO2 variations that is related to the dynamics of the volcano. Some inconsistent trends are observed in the two sectors during specific periods, such as in 2012, which is probably due to the marked dynamics affecting the eastern flank compared to the more stable southwestern one.1223 52 - PublicationRestrictedSalinity variations in the water resources fed by the Etnean volcanic aquifers (Sicily, Italy): natural vs. anthropogenic causes(2011)
; ; ; ; ; ;D'Alessandro, W.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia ;Bellomo, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia ;Bonfanti, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia ;Brusca, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia ;Longo, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia; ; ; ; In this paper, in an attempt to reveal possible changes connected to natural or anthropogenic causes, the main results of hydrogeochemical monitoring carried out at Mount Etna are evaluated. We report on the salinity contents of the groundwaters that flow in fractured volcanics, which make up the flanks of the volcano. These waters, analyzed for major ion chemistry, were sampled regularly from 1994 to 2004. Basing on nonparametric Sen’s slope estimator, time series of groundwater composition reveal that the salinity of most of the Etnean aquifers increased by 0.5% to 3.5% each year during this period. This change in the water chemistry is clearly referable to the overexploitation of the aquifers. This increasing trend needs to be inverted urgently; otherwise, it will cause a shortage of water in the near future, because the maximum admissible concentration of salinity for drinking water will be exceeded.889 35 - PublicationRestrictedRainwater Chemistry at Mt. Etna (Italy): natural and anthropogenic sources of major ions(2003)
; ; ; ;Aiuppa, A.; Dipartimento CFTA, Università di Palermo, via Archirafi 36, I-90123 Palermo, Italy ;Bonfanti, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia ;D'Alessandro, W.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia; ; Major ion content of 37 wet-only rainwater samples collected on the southern flank of Mount Etna volcano was investigated. Measured pH values range from 3.80 to 7.22 and display a positive correlation with Ca2+ and an inverse correlation with NO−3 , suggesting that anthropogenic NOx are the most effective acidifying agents while Ca, likely as solid CaCO3, is the prevailing proton acceptor. Na/Cl ratios indicate a dominant marine origin for both species, while K, mg and Ca contents point to additional sources (soil dust, fertilisers etc.). Nitrate and sulphate concentrations display a nearly constant ratio indicating a common anthropogenic origin, and only a few samples are characterised by sulphate excess. The analysis of time series reveals a good correlation between the excess sulphate in rainwater and SO2 fluxes from the summit craters plume. Non sea salt chloride contents show also a significant correlation with volcanic activity indicating a magmatic sulphur and chloride contribution to rainwater. Meteoric flux estimations point to a prevailing magmatic origin for sulphur in the collected rainwaters while sea spray is the main source of chlorine.2773 98
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