http://hdl.handle.net/2122/374 Ricerca nel canale cerca http://www.earth-prints.org/simple-search http://hdl.handle.net/2122/6066 Titolo: Carbon dioxide diffuse emission from the soil: ten years of observations at Vesuvio and Campi Flegrei (Pozzuoli), and linkages with volcanic activity<br/><br/>Autori: Granieri, D.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia; Avino, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Chiodini, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia<br/><br/>Abstract: Carbon dioxide flux from the soil is regularlymonitored in selected areas of Vesuvio and Solfatara(Campi Flegrei, Pozzuoli) with the twofold aim of i)monitoring spatial and temporal variations of the degassingprocess and ii) investigating if the surface phenomena couldprovide information about the processes occurring at depth.At present, the surveyed areas include 15 fixed pointsaround the rim of Vesuvio and 71 fixed points in the floorof Solfatara crater. Soil CO2 flux has been measured since1998, at least once a month, in both areas. In addition, twoautomatic permanent stations, located at Vesuvio andSolfatara, measure the CO2 flux and some environmentalparameters that can potentially influence the CO2 diffusedegassing. Series acquired by continuous stations arecharacterized by an annual periodicity that is related tothe typical periodicities of some meteorological parameters.Conversely, series of CO2 flux data arising from periodicmeasurements over the arrays of Vesuvio and Solfatara areless dependent on external factors such as meteorologicalparameters, local soil properties (porosity, hydraulic conductivity)and topographic effects (high or low ground).Therefore we argue that the long-term trend of this signalcontains the “best” possible representation of the endogenoussignal related to the upflow of deep hydrothermalfluids. http://hdl.handle.net/2122/6065 Titolo: Long term variations of the Campi Flegrei (Italy) volcanic system as revealed by the monitoring of hydrothermal activity<br/><br/>Autori: Chiodini, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Caliro, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Cardellini, C.; Dipartimento di Scienze della Terra, Università di Perugia, Perugia,Italy; Granieri, D.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia; Avino, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Baldini, A.; Dipartimento di Scienze della Terra, Università di Perugia, Perugia,Italy; Donnini, M.; Dipartimento di Scienze della Terra, Università di Perugia, Perugia,Italy; Minopoli, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia<br/><br/>Abstract: Long duration time-series of the chemical composition of fumaroles and of soil CO2 flux revealthat important variations in the activity of the Solfatara fumarolic field, the most importanthydrothermal site of Campi Flegrei, occurred in the 2000-2008 period. A continuous increase of theCO2 concentrations, and a general decrease of the CH4 concentrations are interpreted as theconsequence of the increment of the relative amount of magmatic fluids, rich in CO2 and poor inCH4, hosted by the hydrothermal system. Contemporaneously, the H2O-CO2-He-N2 gas systemshows remarkable compositional variations in the samples collected after July 2000 with respect tothe previous ones, indicating the progressive arrival at the surface of a magmatic componentdifferent from that involved in the 1983-84 episode of volcanic unrest (1983-1984 bradyseism).The change starts in 2000 concurrently with the occurrence of relatively deep, long-period seismicevents which were the indicator of the opening of an easy-ascent pathway for the transfer ofmagmatic fluids towards the shallower, brittle domain hosting the hydrothermal system. Since 2000,this magmatic gas source is active and causes ground deformations, seismicity as well as theexpansion of the area affected by soil degassing of deeply derived CO2. Even though the activitywill most probably be limited to the expulsion of large amounts of gases and thermal energy, asobserved in other volcanoes and in the past activity of Campi Flegrei, the behavior of the system inthe future is, at the moment, unpredictable. http://hdl.handle.net/2122/6035 Titolo: Insights into fluid circulation across the Pernicana Fault (Mt. Etna, Italy) and implications for flank instability<br/><br/>Autori: Siniscalchi, A.; Dipartimento di Geologia e Geofisica, Università degli Studi di Bari, via Orabona, 4-70125, Bari-Italy; Tripaldi, S.; Dipartimento di Geologia e Geofisica, Università degli Studi di Bari, via Orabona, 4-70125, Bari-Italy; Neri, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Giammanco, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Piscitelli, S.; Istituto di Metodologie per l' Analisi Ambientale, CNR, Tito (PZ), Italy; Balasco, M.; Istituto di Metodologie per l' Analisi Ambientale, CNR, Tito (PZ), Italy; Behncke, B.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Magri, C.; Dipartimento di Geologia e Geofisica, Università degli Studi di Bari, via Orabona, 4-70125, Bari-Italy; Naudet, V.; Université Bordeaux 1, Geosciences Hydrosciences Material and Constructions, GHYMAC-EA 4134, Talence, F-33405, France; Rizzo, E.; Istituto di Metodologie per l' Analisi Ambientale, CNR, Tito (PZ), Italy<br/><br/>Abstract: We conducted geophysical–geochemical measurements on a ∼2 kmN–S profile cutting across the PernicanaFault, one of the most active tectonic features on the NE flank of Mt. Etna. The profile passes from theunstable E flank of the volcano (to the south) to the stable N flank and significant fluctuations in electricalresistivity, self-potential, and soil gas emissions (CO2, Rn and Th) are found. The detailed multidisciplinaryanalysis reveals a complex interplay between the structural setting, uprising hydrothermal fluids, meteoricfluids percolating downwards, ground permeability, and surface topography. In particular, the recoveredfluid circulation model highlights that the southern sector is heavily fractured and faulted, allowing theformation of convective hydrothermal cells. Although the existence of a hydrothermal system in a volcanicarea does not surprise, these results have great implications in terms of flank dynamics at Mt. Etna. Indeed,the hydrothermal activity, interacting with the Pernicana Fault activity, could enhance the flank instability.Our approach should be further extended along the full extent of the boundary between the stable andunstable sectors of Etna for a better evaluation of the geohazard in this active tectonic area. http://hdl.handle.net/2122/6016 Titolo: Long term variations at Campi Flegrei (Italy) volcanic system highlighted by the monitoring of hydrothermal activity<br/><br/>Autori: Chiodini, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Caliro, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Cardellini, C.; Dipartimento scienze della Terra Università di Perugia, Italy; Granieri, D.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia; Avino, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Baldini, A.; Dipartimento scienze della Terra Università di Perugia, Italy; Donnini, M.; Dipartimento scienze della Terra Università di Perugia, Italy; Minopoli, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia<br/><br/>Abstract: Long time-series of chemical composition of fumaroles and of soil CO2 flux reveal that important variations in theactivity of Solfatara fumarolic field, the most important hydrothermal site of Campi Flegrei, occurred in the 2000-2008 period. A continuous increase of the CO2 concentration and a general decrease of the CH4 concentration areinterpreted as the consequence of the increment of the relative amount of magmatic fluids, rich in CO2 and poor inCH4, hosted by the hydrothermal system. Contemporaneously the H2O-CO2-He-N2 gas system shows remarkablecompositional variations in the samples collected after July 2000 with respect to the previous ones, indicating theprogressive arrival at the surface of a magmatic component different from that involved in the 1983-84 bradyseism.The change starts in 2000 concurrently with the occurrence of relatively deep long periods seismic events which, inour interpretation, were the indicator of the opening of an easy pathway for the transfer of magmatic fluids towardsthe shallower, brittle domain hosting the hydrothermal system. Since 2000 this magmatic gas source is active andcauses ground deformations, seismicity as well as the expansion of the area interested by diffuse soil degassing ofdeeply derived CO2. http://hdl.handle.net/2122/6015 Titolo: Carbon dixide emission in Italy: Shallow crustal sources or subduction related fluid recycling?<br/><br/>Autori: Chiodini, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Avino, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Caliro, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Cardellini, C.; Università di Perugia, Dipartimento di Scienze della Terra piazza Università, 06123 Perugia, Italy; Costa, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Frondini, F.; Università di Perugia, Dipartimento di Scienze della Terra piazza Università, 06123 Perugia, Italy<br/><br/>Abstract: Anomalous non-volcanic CO2 release in central andsouthern Italy has been highlighted by ten years of detailedinvestigations on Earth degassing processes. Two regionaldegassing structures are located in the Tyrrhenian sectorwhere more then 200 emissions of CO2 are located and hasbeen recently included in the first web based catalogue ofdegassing sites (http://googas.ov.ingv.it). The total amount ofCO2 released by the two structures were evaluated to be >2×1011 mol a-1 ( >10% of the estimated global volcanic CO2emission). The anomalous flux of CO2 suddenly disappears inthe Apennine in correspondence of a narrow band where mostof the Italian seismicity concentrates. Here, at depth, the gasaccumulates in crustal traps generating CO2 overpressurisedreservoirs. These overpressured structures are, in our opinion,one of the main cause of Apennine earthquake activationprocesses. The results of these investigations suggested thatEarth degassing in Italy may have an active primary role in thegeodynamics of the region. What is the origin of gas? Thelarge extension of the degassing structures and petrologic datasuggested that the main source of gas is a mantlemetasomatised by the fluids produced in the subdacted slabs.However, has been also hypothesised the presence of localisedcrustal source of the gas. This matter will be discussed on thebase of unpublished isotopic data of the main gas emissions. http://hdl.handle.net/2122/6005 Titolo: Magma degassing episodes and volcanic unrest periods in quiescent volcanoes<br/><br/>Autori: Chiodini, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia<br/><br/>Abstract: Long time series of fumarolic chemical and isotopic compositions, at Solfatara (Campi Flegrei) and Vulcano highlight the occurrence of mixing processes among magmatic and hydrothermal fluids. At Solfatara temperatures of about 360°C of the hydrothermal system are inferred by methane chemical-isotopic geoindicators and by the H2/Ar geothermometer. These high temperatures are representative of a deep zone where magmatic gases flash hydrothermalliquid forming a gas pIume where the kinetically fast reactive species (H2 and CO) re-equilibrate at temperatures of 200240°C. The stable isotope compositions of the two dominant species, i.e, H20 and C02, shows that sampled effluents are mixture between magmatic fluids and the vapor generated at about 360°C by the vaporization of hydrothermalliquids of meteotic origino Similar mixing processes between magmatic fluids and a hydrothermal component of marine origin have been recognized at Vulcano high temperature fumaroleso In both the system a typical 'andesitic' water type composition and high C02 contents characterizes the magmatic component. Our hypothesis is that pulsing injections of these C02-rich magmatic fluids at the bottom of the hydrothermal systems trigger the bradyseismic crises, periodically affecting Campi Flegrei, and the periodical volcanic unrest periods of Vulcano. At Campi Flegrei a strong increase of the fraction of the magmatic component, marked in fact the bradyseismic crisis of 1982-84 and four minor episodes occurred in 1989, 1994 and 2000 and 2006. Increases of the magmatic component in the fumaroles of Vulcano were recorded in 1979-1981, 1985, 1988, 1996, 2004 and 2005 concurrently with anomalous seismic activity localized in the erater area. Physical-numerical simulations of the injection of hot, C02 rich fluids at the base of a hydrothermal system, asses the physical feasibility the processo Ground deformations, gravitational anomalies and seismic crisis can be well explained by the complex fluid dynamic processes caused by magma degassing episodes. Data on the fumaroles of other volcanoes, for example Vesuvio, Panarea, Nisyros (Greece), Mammoth (California), suggest that magma degassing episodes frequently occur in dormant volcanoes causing volcanic unrest processes not necessarily linked to magma movement but rather to pulsating degassing processes from deep pressurized, possibly stationary, magma bodies. http://hdl.handle.net/2122/5849 Titolo: Carbon-14 as a marker of seismic activity<br/><br/>Autori: Mostaccia, D.; Chiodini, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Berti, C.; Tinazzi, O.<br/><br/>Abstract: The principle of carbon-14 dating is well known (1): the content of this radioisotope in a sampleof an animal or a plant origin is assessed and the time elapsed from the formation of the organicmaterial to the moment of assessment is calculated comparing the present content of carbon-14 to that at the time the plant or animal was alive. This last is assumed at equilibrium withthe atmospheric concentration of carbon-14, which, in turn, is assumed to have been constantthrough the ages. Knowing the decay constant of carbon-14, the time elapsed is deduced. Then thiscalculated age is entered in calibration diagrams that account for the actual variable atmosphericcontent through the years, to obtain the age of the sample, or more precisely, a time interval inwhich the age falls. Thus, the main idea behind the technique is that the atmospheric concentrationof carbon-14 marked CO2 is essentially constant, or slowly variable, from year to year. To this, oneword of caution needs be added: after WW2, and particularly from the 1950s, the concentrationof carbon-14 in the atmosphere has become quite erratic due to nuclear weapon tests, and hencethis technique is not used for dating samples from that time on.In the present work, the whole carbon-14 idea has been reused in a somewhat different context,and with a different purpose in mind.Afact to be kept in mind is thatCO2 contained in vast amountswithin the Earth’s crust beneath the volcanic apparatus, the so-called fossil CO2, either degassedby the mantle or having been formed by metamorphic reactions in the crust, contains no traceof the carbon-14 isotope. Fossil CO2 release is often associated to seismic and volcanic activity:the question may then arise whether, on occasion of such major releases and in the presence oflandscape conformation conducive to slow mixing (narrow valley bottoms, canyons, and the like),the carbon-14 contents of local vegetation may be affected by the presence of spent CO2. TheSolfatara at Pozzuoli presented both the above-mentioned conditions: it has the required shapeand it has endured large releases of fossil CO2 in the early 1980s. It presented itself as an ideallocation to test this hypothesis. There are pine trees planted in the 1930s, as part of a reforestationplan: it was possible to select two recently dead trees, one in the Solfatara area and presumably asaffected by the CO2 release as could be possible, and the other immediately outside and upwindof the area, constituting an ideal blank. Sections were taken from the two trees and analysed todetermine the carbon-14 content of several rings corresponding to the years of interest. In thefollowing sections, the method and the results will be presented and commented upon. http://hdl.handle.net/2122/5838 Titolo: CO2/CH4 ratio in fumaroles a powerful tool to detect magma degassing episodes at quiescent Volcanoes<br/><br/>Autori: Chiodini, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia<br/><br/>Abstract: Long time series of fumarolic compositions at CampiFlegrei (Italy), Mammoth Mountain (California), Panarea(Italy) and Nisyros (Greece) show rapid increases, up toorders of magnitude, of the CO2/CH4 ratio systematicallywith the occurrence of volcanic unrest periods. These easilydetected anomalies originate with the arrival of CH4-poormagmatic fluids in the shallower levels of the volcanoes. Thedata suggest that volcanoes are characterized by magmaticactivity at depth also in periods of apparent quiescence.The activity is constituted by the pulsing release of largeamount of fluids which either cause unrest periods(seismicity and ground deformation) or possibly couldprecede volcanic eruption. This type of volcanic activitycan be monitored trough the classical geophysical techniquestogether with the systematic sampling and analysis offumaroles. http://hdl.handle.net/2122/5828 Titolo: Mercury content and speciation in the Phlegrean Fields volcanic complex: Evidence from hydrothermal system and fumaroles<br/><br/>Autori: Bagnato, E.; Dipartimento CFTA, Università di Palermo, Italy; Parello, F.; Dipartimento CFTA, Università di Palermo, Italy; Valenza, M.; Dipartimento CFTA, Università di Palermo, Italy; Caliro, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia<br/><br/>Abstract: Mercury is outstanding among the global environmental pollutants of continuing concern. Althoughdegassing of active volcanic areas represents an important natural source of mercury into the atmosphere,still little is known about the amount and behaviour of Hg in volcanic aquifers, especially regarding itschemical speciation. In order to assess the importance of mercury emissions from active volcanoes, thermalwaters were sampled in the area surrounding La Solfatara, Pozzuoli bay. This is the most active zone of thePhlegrean Fields complex (coastal area north–west of Naples), with intense hydrothermal activity at presentday. Studied groundwaters show total Hg (THg) concentrations range from 56 to 171 ng/l and are lower thanthe 1000 ng/l threshold value for human health protection fixed by the World Health Organization (WHO,1993). We also carefully discriminated the different aqueous species of Hg in the collected water samples.Besides, original data on Hg determination in gaseous manifestations at La Solfatara crater are also reported.We measured volcanogenic mercury concentration and Hg/Stot ratio both in the volcanic plume and infumarolic condensates in order to better constrain Hg reactivity once emitted into the atmosphere. Data onHg/Stot reveal that there is no significant difference between Hg volcanic composition at the venting source(fumaroles) and in near-vent diluted volcanic plumes (1.6×10−5 and 1.9×10−5, respectively), suggestingthat there is limited Hg chemical processing in volcanic fumarole plumes, at least on the timescales of a fewseconds investigated here. Combining the mean fumaroles Hg/CO2 mass ratio of about 1.3×10−8 (molarratio: 2.1×10−9) with the hydrothermal soil diffuse CO2 degassing of the area, the annual Hg flux from LaSolfatara is estimated as 7 kg y−1 (0.007 t y−1). Current mercury emission from La Solfatara volcanorepresents a very small contribution to the estimated global volcanic budget for this element, and theestimated Hg flux is considerably lower than that estimated from open-conduit active basaltic volcanoes. http://hdl.handle.net/2122/5827 Titolo: Carbon dioxide degassing and thermal energy release in the Monte Amiata volcanic-geothermal area (Italy)<br/><br/>Autori: Frondini, F.; Dipartimento di Scienze della Terra, Università di Perugia, Piazza dell’Università, I-06123 Perugia, Italy; Caliro, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Cardellini, C.; Dipartimento di Scienze della Terra, Università di Perugia, Piazza dell’Università, I-06123 Perugia, Italy; Chiodini, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Morgantini, N.; ARPA Umbria, Via Pievaiola, San Sisto, I-06132 Perugia, Italy<br/><br/>Abstract: The quaternary volcanic complex of Mount Amiata is located in southern Tuscany (Italy) and representsthe most recent manifestation of the Tuscan Magmatic Province. The region is characterised by a largethermal anomaly and by the presence of numerous CO2-rich gas emissions and geothermal features,mainly located at the periphery of the volcanic complex. Two geothermal systems are located, at increasingdepths, in the carbonate and metamorphic formations beneath the volcanic complex. The shallowvolcanic aquifer is separated from the deep geothermal systems by a low permeability unit (LigurianUnit). A measured CO2 discharge through soils of 1.8 109 mol a 1 shows that large amounts of CO2move from the deep reservoir to the surface. A large range in d13CTDIC ( 21.07 to +3.65) characterisesthe waters circulating in the aquifers of the region and the mass and isotopic balance of TDIC allows distinguishinga discharge of 0.3 109 mol a 1 of deeply sourced CO2 in spring waters. The total natural CO2discharge (2.1 109 mol a 1) is slightly less than minimum CO2 output estimated by an indirect method(2.8 109 mol a 1), but present-day release of 5.8 109 mol a 1 CO2 from deep geothermal wells mayhave reduced natural CO2 discharge. The heat transported by groundwater, computed considering theincrease in temperature from the infiltration area to the discharge from springs, is of the same orderof magnitude, or higher, than the regional conductive heat flow (>200 mWm 2) and reaches extremelyhigh values (up to 2700mWm 2) in the north-eastern part of the study area. Heat transfer occurs mainlyby conductive heating in the volcanic aquifer and by uprising gas and vapor along fault zones and in thoseareas where low permeability cover is lacking. The comparison of CO2 flux, heat flow and geological settingshows that near surface geology and hydrogeological setting play a central role in determining CO2degassing and heat transfer patterns.