http://hdl.handle.net/2122/262 2013-05-21T07:21:40Z http://hdl.handle.net/2122/8697 Title: Sulphur-gas concentrations in volcanic and geothermal areas in Italy and Greece: Characterising potential human exposures and risks Authors: D'Alessandro, W.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia; Aiuppa, A.; Università di Palermo, Dipartimento DiSTeM; Bellomo, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia; Brusca, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia; Calabrese, S.; Università di Palermo, Dipartimento DiSTeM; Kyriakopoulos, K.; University of Athens, Dept. Geology and Geoenvironment, Greece; Liotta, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia; Longo, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia Abstract: Passive samplers were used to measure the atmospheric concentrations of SO2 naturally emitted at three volcanoes in Italy (Etna, Vulcano and Stromboli) and of H2S naturally emitted at three volcanic/geothermal areas in Greece (Milos, Santorini and Nisyros). The measured concentrations and dispersion patterns varied with the strength of the source (open conduits or fumaroles), the meteorological conditions and the area topography. At Etna, Vulcano and Stromboli, SO2 concentrations reach values that are dangerous to people affected by bronchial asthma or lung diseases (>1000 μg m−3). H2S values measured at Nisyros also exceed the limit considered safe for the same group of people (>3000 μg m−3). The data obtained using passive samplers represent time-averaged values over periods from a few days up to 1 month, and hence concentrations probably reached much higher peak values that were potentially also dangerous to healthy people. The present study provides evidence of a peculiar volcanic risk associated with tourist exploitation of active volcanic areas. This risk is particularly high at Mt. Etna, where the elderly and people in less-than-perfect health can easily reach areas with dangerous SO2 concentrations via a cableway and off-road vehicles 2013-07-31T22:00:00Z http://hdl.handle.net/2122/8631 Title: Radon in outdoor air in the Mt. Etna area, Italy Authors: Vaupotič, J.; Department of Environmental Sciences, Radon Center, Jožef Stefan Institute; Zvab, P.; Faculty of Natural Sciences and Engineering, University of Ljubljana; Giammanco, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia Abstract: Radon (222Rn) activity concentration in outdoor air was measured, using AlphaGuard radon monitors, at 25 points in the Mt. Etna area, at different distances and in different directions from the summit. Values of up to 93 Bq·m–3 were found at three points close to the summit, at altitudes of about 3000 m above the sea level, and in the range of 3.0–19.6 Bq·m–3 elsewhere. An average radon concentration of 7.9 Bq·m–3 was obtained in the northern region, 4.8 Bq·m–3 in the eastern (oriented towards the sea), 9.6 Bq·m–3 in the western (the furthest inland), and 6.5 Bq·m–3 in the southern. 2010-09-30T22:00:00Z http://hdl.handle.net/2122/8583 Title: An innovative method for continuous measurement of soil CO2 flux Authors: De Gregorio, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia; Camarda, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia; Cappuzzo, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia; Gurrieri, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia Abstract: Herein, we present a method for continuous measurement of soil CO2 flux that is completely new and distinct from existing instruments. The foremost difference is that instead of using an infrared gas analyser (IRGA), the new device measures soil CO2 flux by means of a simple pressure sensor, measuring pressure transients inside a closed polymeric tube inserted into the soil. This allows continuous measurements even in soil placed in environments that could potentially damage IRGA. In addition, due to the innovative operating principle, measurements of soil CO2 flux can be effortlessly performed also in strongly harsh weather conditions. Theoretical equations were derived for calculating soil CO2 flux solely using measured transient values. The reliability of the equations was rigorously tested with a variety of experiments. Continuous measurements over four months, acquired in a high-emission area on the Island of Vulcano, compared favourably with the data obtained using an established method. 2013-02-28T23:00:00Z http://hdl.handle.net/2122/8515 Title: Vent temperature trends at the Vulcano Fossa fumarole field: the role of permeability Authors: Harris, A.; Laboratoire Magmas et Volcans, Université Blaise Pascal; Alparone, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Bonforte, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Dehn, J.; University of Alaska Fairbanks; Gambino, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Lodato, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Spampinato, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia Abstract: Between 1994 and 2010, we completed 16 thermal surveys of Vulcano’s Fossa fumarole field (Aeolian Islands, Italy). In each survey, between 400 and 1,200 vent temperatures were collected using a thermal infrared thermometer from distances of ∼1 m. The results show a general decrease in average vent temperature during 1994–2003, with the average for the entire field falling from ∼220°C in 1994 to ∼150°C by 2003. However, between 2004 and 2010, we witnessed heating, with the average increasing to ∼190°C by 2010. Alongside these annual-scale field-wide trends, we record a spatial re-organisation of the fumarole field, characterised by shut down of vent zones towards the crater floor, matched by rejuvenation of zones located towards the crater rim. Heating may be expected to be associated with deflation because increased amounts of vaporisation will remove volume from the hydrothermal system Gambino and Guglielmino (J Geophys Res 113: B07402, 2008). However, over the 2004–2010 heating period, no ground deformation was observed. Instead, the number of seismic events increased from a typical rate of 37 events per month during 1994–2000 to 195 events per month during 2004–2010. As part of this increase, we noticed a much greater number of high-frequency events associated with rock fracturing. We thus suggest that the heating event of 2004–2010 was the result of changed permeability conditions, rather than change in the heat supply from the deeper magmatic source. Within this scenario, cooling causes shut down of lower sectors and re-establishment of pathways located towards the crater rim, causing fracturing, increased seismicity and heat flow in these regions. This is consistent with the zone of rejuvenation (which lies towards and at the rim) being the most favourable location for fracturing given the stress field of the Fossa cone Schöpa et al. (J Volcanol Geotherm Res 203:133–145, 2011); it is also the most established zone, having been active at least since the early twentieth century. Our data show the value of deploying multi-disciplinary geophysical campaigns at degassing (fumarolic) hydrothermal systems. This allows more complete and constrained understanding of the true heat loss dynamics of the system. In the case study presented here, it allows us to distinguish true heating from apparent heating phases. While the former are triggered from the bottom-up, i.e. they are driven by increases in heat supply from the magmatic source, the latter are triggered from the top-down, i.e. by changing permeability conditions in the uppermost portion of the system to allow more efficient heat flow over zones predisposed to fracturing. 2011-12-31T23:00:00Z http://hdl.handle.net/2122/8406 Title: A literature review and new data of trace metals fluxes from worldwide active volcanoes Authors: Calabrese, S.; Università di Palermo, Dipartimento DiSTeM; Scaglione, S.; Università di Palermo, Dipartimento DiSTeM; D'Alessandro, W.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia; Brusca, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia; Bellomo, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia; Parello, F.; Università di Palermo, Dipartimento DiSTeM Editors: Corsaro, R.A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia Abstract: Volcanic emissions are considered one of the major natural sources of several trace metals (e.g. As, Cd, Cu, Pb, and Zn) to the atmosphere [Nriagu, 1989], and the geochemical cycles of these elements have to be considered strongly influenced by volcanic input. However, the accurate estimation of the global volcanic emissions of volatile trace metals into the atmosphere is still affected by a high level of uncertainty. The latter depends on the large variability in the emission of the different volcanoes, and on their changing stage of activity. Moreover, only few of the potential sources in the world have been directly measured [Hinkley et al. 1999]. Atmospheric deposition processes (wet and dry) are the pathways through which volcanic emissions return to the ground (soils, plants, aquifers), resulting in both harmful and beneficial effects [Baxter et al. 1982; Aiuppa et al. 2000; Brusca et al. 2001; Delmelle, 2003; Bellomo et al. 2007; Martin et al. 2009; Floor et al. 2011; Calabrese et al. 2011]. In the first part of this study we present the results of a literature review on trace metals emissions from active volcanoes around the world. In the second part, we present new data on the fluxes of the trace metals from Etna (Italy) and four active volcanoes in the world: Turrialba (Costarica), Nyiragongo (DRC), Mutnovsky and Gorely (Kamchatka). We found 27 publications (the first dating back to the 70’s), 13 of which relate to the Etna and the other include some of the world’s most active volcanoes: Mt. St. Helens, Erebus, Merapi, White Island, Kilauea, Popocatepetl, Galeras, Indonesian arc, Satasuma and Masaya. The review shows that currently there are very few data available, and that the most studied volcano is Mt. Etna. Using these data, we defined a range of fluxes for As, Ba, Bi, Cd, Cu, Fe, Mn, Pb, Se, V and Zn (Figure 1). To obtain new data we sampled particulate filters at the five above mentioned volcanoes. Filters were mineralized (acid digestion) and analyzed by ICP-MS. Sulphur to trace element ratios were related to sulphur fluxes to indirectly estimate trace elements fluxes. Etna confirms to be one of the greatest point sources in the world. The Nyiragongo results to be also a significant source of metals to the atmosphere, especially considering its persistent state of degassing from the lava lake. Also Turrialba and Gorely have high emission rates of trace metals considering the global range. Only Mutnovsky Volcano show values which are sometimes lower than the range obtained from the review, consistent with the fact that it is mainly a fumarolic field. This work highlights the need to expand the current dataset including many other active volcanoes for a better constraint of global trace metal fluxes from active volcanoes. 2012-12-11T23:00:00Z http://hdl.handle.net/2122/8405 Title: Rain-ash interaction during paroxysmal events as potential input of toxic trace element in the environment: example from Mt. Etna Volcano Authors: Calabrese, S.; Università di Palermo, Dipartimento DiSTeM; D'Alessandro, W.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia; Parello, F.; Università di Palermo, Dipartimento DiSTeM Editors: Corsaro, R.A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia Abstract: Volcanic emissions represent one of the most relevant natural sources of trace elements to the troposphere, both during and between eruptions. Due to their potential toxicity they may have important environmental impacts from the local to the global scale. Mount Etna, the largest European volcano and one of the most active volcano in the world, covers an area of about 1250 km2 and reaches an altitude of about 3340 m. It has been persistently active during historical time, with frequent paroxysmal episodes separated by passive degassing periods. Atmospheric precipitation was collected approximately every two weeks, from April 2006 to December 2007, using a network of five rain gauges, located at various altitudes on the upper flanks around the summit craters of Etna Volcano. The collected samples were analysed for major (Ca, Mg, K, Na, F, SO4, Cl, NO3) and a large suite of trace elements (Ag, Al, As, Au, B, Ba, Be, Bi, Cd, Co, Cr, Cs, Cu, Fe, Hg, La, Li, Mn, Mo, Ni, Pb, Rb, Si, Sb, Sc, Se, Sr, Th, Ti, Tl, U, V, Zn) by using different techniques (IC, SPEC, ICP-MS and CV-AFS). The monitoring of atmospheric deposition gave the opportunity to occasionally sample volcanic fresh ashes emitted by the volcano during the paroxysmal events. This was possible because the network of five rain gauges were equipped with a filter-system to block the coarse material. In this way, more than twenty events of ashfall were collected. Unfortunately, only half of these samples were suitable for a complete chemical analysis, because of the small amount of sample. In order to obtain elemental chemical composition of ashes, powdered samples were analysed by a combination of methods, including X-ray Fluorescence Spectroscopy (XRF), total digestion followed by Inductively Coupled Plasma Emission Mass Spectrometry (ICP-MS), Instrumental Neutron Activation Analysis (INAA), and infrared detection (IR). The chemistry of rainwater reveals that most of the investigated elements have higher concentrations close to the emission vent of the volcano, confirming the prevailing volcanic contribution. Rainwater composition clearly reflects the volcanic plume input. Ash-normalised rainwater composition indicates a contrasting behaviour between volatile elements, which are highly-enriched in rainwater, and refractory elements, which have low rainwater/ash concentration ratios. The degree of interaction between collected ash and rainwater was variable, depending on several factors: (i) the length of the period in which tephra was present in the sampler (the ash fall may have occurred any day from the first to the last day of the rain collecting period); (ii) the amount of rainwater fallen on the collectors after the ash-fall event, and its acidity; (iii) the granulometry of the ash samples that was widely variable (from few centimetres to micrometric particles) increasing the interaction with decreasing dimensions of the grains; (iv) the distance of collector with respect to the craters. In order to investigate the role of volcanic ash on the evolution of the rainwater chemistry, absolute concentrations of rain and ash were plotted in binary plot diagrams (Figure 1). Each diagram corresponds to a single event, and pH and TDS of the solution collected is reported. The diagonal bars in the diagrams represent the rain/ash ratios (1:1 and 1:10000). The results confirm that sulphate and halide salt aerosols are adsorbed onto ash particles, and their rate of dissolution in rainwater depends on solubility. Moreover, rapid chemical weathering of the silicate glass by volcanic acid (SO2, HCl and HF) can also explain the enrichment of several refractory elements (Na, K, Ca, Mg, Si, Al, Fe, Ti, Sc). Our observations highlight how explosive activity can increase enormously the deposition rate of several chemical elements, up to several km away from the emission vents. 2012-12-11T23:00:00Z http://hdl.handle.net/2122/8312 Title: Insights from fumarole gas geochemistry on the origin of hydrothermal fluids on the Yellowstone Plateau Authors: Chiodini, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Caliro, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Lowenstern, J. B.; US Geological Survey, Menlo Park, CA, USA; Evans, W. C.; US Geological Survey, Menlo Park, CA, USA; Bergfeld, D.; US Geological Survey, Menlo Park, CA, USA; Tassi, F.; Department of Earth Sciences, University of Florence, Florence, Italy; Tedesco, D.; Department of Environmental Sciences, University of Napoli 2, Italy Abstract: The chemistry of Yellowstone fumarole gases shows the existence of two component waters, type MC, influenced by the addition of deep mantle fluid, and type CC, influenced by crustal interactions (CC). MC is high in 3He/4He (22 Ra) and low in 4He/40Ar ( 1), reflecting input of deep mantle components. The other water is characterized by 4He concentrations 3–4 orders of magnitude higher than air-saturated meteoric water (ASW). These high He concentrations originate through circulation in Pleistocene volcanic rocks, as well as outgassing of Tertiary and older (including Archean) basement, some of which could be particularly rich in uranium, a major 4He source. Consideration of CO2–CH4–CO–H2O–H2 gas equilibrium reactions indicates equilibration temperatures from 170 C to 310 C. The estimated temperatures highly correlate with noble-gas variations, suggesting that the two waters differ in temperature. Type CC is 170 C whereas the MC is hotter, at 340 C. This result is similar to models proposed by previous studies of thermal water chemistry. However, instead of mixing the deep hot component simply with cold, meteoric waters we argue that addition of a 4He-rich component, equilibrated at temperatures around 170 C, is necessary to explain the range in fumarole gas chemistry. 2011-12-31T23:00:00Z http://hdl.handle.net/2122/8308 Title: New insights into volcanic processes at Stromboli from Cerberus, a remote-controlled open-path FTIR scanner system Authors: La Spina, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Burton, M. R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia; Harig, R.; TUHH, Technical University of Hamburg-Harburg, Hamburg, Germany; Mure, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Rausch, P.; TUHH, Technical University of Hamburg-Harburg, Hamburg, Germany; Jordan, M.; TUHH, Technical University of Hamburg-Harburg, Hamburg, Germany; Caltabiano, T.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia Abstract: The ordinary, low intensity, activity of Stromboli volcano is sporadically interrupted by more energetic events termed, depending on their intensity, “major explosions” and “paroxysms”. These short-lived energetic episodes represent a potential risk to visitors to the highly accessible summit of Stromboli. Observations made at Stromboli over the last decade have shown that the composition of gas emitted from the summit craters may change prior to such explosions, allowing the possibility that such changes may be used to forecast these potentially dangerous events. In 2008 we installed a novel, remote-controlled, open-path FTIR scanning system called Cerberus at the summit of Stromboli, with the objective of measuring gas compositions from individual vents within the summit crater terrace of the volcano with high temporal resolution and for extended periods. In this work we report the first results from the Cerberus system, collected in August-September 2009, November 2009 and May-June 2010. We find significant, fairly consistent, intra-crater variability for CO2/SO2 and H2O/CO2 ratios, and relatively homogeneous SO2/HCl ratios. In general, the southwest crater is richest in CO2, and the northeast crater poorest, while the central crater is richest in H2O. It thus appears that during the measurement period the southwest crater had a somewhat more direct connection to a primary, deep degassing system; whilst the central and northeast craters reflect a slightly more secondary degassing nature, with a supplementary, shallow H2O source for the central crater, probably related to puffing activity. Such water-rich emissions from the central crater can account for the lower crystal content of its eruption products, and emphasise the role of continual magma supply to the shallowest levels of Stromboli's plumbing system. Our observations of heterogeneous crater gas emissions and high H2O/CO2 ratios do not agree with models of CO2-flushing, and we show that simple depressurisation during magma ascent to the surface is a more likely model for H2O loss at Stromboli. We highlight that alternative explanations other than CO2 flushing are required to explain distributions of H2O and CO2 amounts dissolved in melt inclusions. We detected fairly systematic increases in CO2/SO2 ratio some weeks prior to major explosions, and some evidence of a decrease in this ratio in the days immediately preceding the explosions, with periods of low, stable CO2/SO2 ratios between explosions otherwise. Our measurements, therefore, confirm the medium term (~ weeks) precursory increases previously observed with MultiGas instruments, and, in addition, reveal new, short-term precursory decreases in CO2/SO2 ratios. immediately prior to the major explosions. Such patterns, if shown to be systematic, may be of great utility for hazard management at Stromboli's summit. Our results suggest that intra-crater CO2/SO2 variability may produce short-term peaks and troughs in CO2/SO2 time series measured with in-situ MultiGas instruments, due simply to variations in wind direction. 2012-12-31T23:00:00Z http://hdl.handle.net/2122/8287 Title: Degassing behaviour of vesiculated basaltic magmas: an example from Ambrym volcano, Vanuatu Arc Authors: Polacci, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia; Baker, D. R.; Earth and Planetary Sciences, McGill University, Montreal, QC H3A2A7, Canada; La Rue, A.; Earth and Planetary Sciences, McGill University, Montreal, QC H3A2A7, Canada; Mancini, L.; Sincrotrone Trieste S.C.p.A., 34149 Basovizza (Trieste), Italy; Allard, P.; Institut de Physique du Globe, Paris Sorbonne Cité, CNRS UMR7154, Paris, France Abstract: Ambrym is one of the most actively erupting basaltic volcanoes in the Vanuatu island arc. Scoria clasts collected from a fallout deposit in the inner terrace of its Benbow active crater were analyzed through series of synchrotron X-ray computed microtomographic experiments, as well as permeability measurements and simulations. Our goal was to reconstruct and visualize scoria textures in 3D and to quantify vesicularity, permeability, vesicle sizes and distributions in order to understand how gas moves in and out of Ambrym basaltic magma. We find that vesicle size distributions in the volume range between ~ 103 and 1010 μm3 define two scoria classes. Vesicle size distributions in the low-to-moderately (0.44–0.67) vesicular samples can be fit by power laws with an exponent of 1 ± 0.2; distributions in the highly vesicular (0.86–0.88) samples can be fit by power laws with a higher exponent (1.4 to 1.7), as well as by exponential fits. Highly vesicular samples exhibit a very pronounced large vesicle, consisting of networks of smaller, interconnected vesicles, that is more than three orders of magnitude larger in volume than all other vesicles in each distribution. This type of vesicle is not found in the low-to-moderately vesicular samples. In addition, vesicle number density negatively correlates with vesicularity: less vesicular samples have the highest number density and vice versa, and contain far more numerous small-to-medium-sized vesicles than highly vesicular samples. Measured and calculated viscous (Darcian) permeabilities overlap in the range 10− 13 and 10− 9 m2, with higher values in the more vesicular samples. We ascribe these differences in the textural and physical properties of the scoria clasts to their derivation from distinct magma portions in the conduit that were driven by convective overturn and underwent different vesiculation histories and gas transport dynamics. Comparing basaltic scoria clasts from Ambrym to those from mild explosive activity at Stromboli volcano (Italy) reveals that differences in their vesicle size distributions may result from the influence of different crystal contents and shapes on the vesiculation and permeability of the respective magmas. Finally, we highlight how rheological properties have a fundamental role in determining the degassing behaviour of basaltic magma at Ambrym and other volcanoes in general. 2012-06-30T22:00:00Z http://hdl.handle.net/2122/8255 Title: Effects of atmospheric conditions on surface diffuse degassing Authors: Rinaldi, A. P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Vandemeulebrouck, J.; Université de Savoie; Todesco, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Fátima, V.; Universitadade dos Açores Abstract: Diffuse degassing through the soil is commonly observed in volcanic areas and monitoring of carbon dioxide flux at the surface can provide a safe and effective way to infer the state of activity of the volcanic system. Continuous measurement stations are often installed on active volcanoes such as Furnas (Azores archipelago), which features low temperature fumaroles, hot and cold CO2 rich springs, and several diffuse degassing areas. As in other volcanoes, fluxes measured at Furnas are often correlated with environmental variables, such as air temperature or barometric pressure, with daily and seasonal cycles that become more evident when gas emission is low. In this work, we study how changes in air temperature and barometric pressure may affect the gas emission through the soil. The TOUGH2 geothermal simulator was used to simulate the gas propagation through the soil as a function of fluctuating atmospheric conditions. Then, a dual parameters study was performed to assess how the rock permeability and the gas source properties affect the resulting fluxes. Numerical results are in good agreement with the observed data at Furnas, and show that atmospheric variables may cause the observed daily cycles in CO2 fluxes. The observed changes depend on soil permeability and on the pressure driving the upward flux. 2012-09-19T22:00:00Z