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  • 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk  (39)
  • 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas  (27)
  • Elsevier  (59)
  • Annual Reviews
  • 2005-2009  (59)
  • 1990-1994
  • 1980-1984
  • 2008  (33)
  • 2007  (26)
Collection
Keywords
Publisher
Years
  • 2005-2009  (59)
  • 1990-1994
  • 1980-1984
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  • 1
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    An expanded non-Arrhenian model for silicate melt viscosity: A treatment for metaluminous, peraluminous and peralkaline liquids (2007)
    Elsevier
    Details
    Publication Date: 2020-10-29
    Description: We present new viscosity measurements for melts spanning a wide range of anhydrous compositions including: rhyolite, trachyte, moldavite, andesite, latite, pantellerite, basalt and basanite. Micropenetration and concentric cylinder viscometry measurements cover a viscosity range of 10−1 to 1012 Pas and a temperature range from 700 to 1650 °C. These new measurements, combined with other published data, provide a high-quality database comprising ∼800 experimental data on 44 well-characterized melt compositions. This database is used to recalibrate the model proposed by Giordano and Dingwell [Giordano, D., Dingwell, D. B., 2003a. Non-Arrhenian multicomponent melt viscosity: a model. Earth Planet. Sci. Lett. 208, 337–349] for predicting the viscosity of natural silicate melts. The present contribution clearly shows that: (1) the viscosity (η)–temperature relationship of natural silicate liquids is very well represented by the VFT equation [log η=A+B/ (T−C)] over the full range of viscosity considered here, (2) the use of a constant high-T limiting value of melt viscosity (e.g., A) is fully consistent with the experimental data, (3) there are 3 different compositional suites (peralkaline, metaluminous and peraluminous) that exhibit different patterns in viscosity, (4) the viscosity of metaluminous liquids is well described by a simple mathematical expression involving the compositional parameter (SM) but the compositional dependence of viscosity for peralkaline and peraluminous melts is not fully controlled by SM. For these extreme compositions we refitted the model using a temperature-dependent parameter based on the excess of alkalies relative to alumina (e.g., AE/SM). The recalibrated model reproduces the entire database to within 5% relative error (e.g., RMSE of 0.45 logunits).
    Description: Published
    Description: 42–56
    Description: reserved
    Keywords: Viscosity ; Model ; Silicate melts ; Metaluminous ; Peraluminous ; Peralkaline ; 04. Solid Earth::04.01. Earth Interior::04.01.05. Rheology ; 04. Solid Earth::04.04. Geology::04.04.05. Mineralogy and petrology ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
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    Experimental solidification of anhydrous latitic and trachytic melts at different cooling rates: the role of nucleation kinetics (2008)
    Elsevier
    Details
    Publication Date: 2020-10-29
    Description: Two sets of cooling experiments were run at atmospheric conditions for two anhydrous starting latitic and trachytic melts: 1) five cooling rates (25, 12.5, 3, 0.5, and 0.125 °C/min) between 1300° and 800 °C, and 2) a 11 0.5 °C/min cooling rate from 1300 °C with quench temperatures at 1200°, 1100°, 1000° and 900 °C. Trachytic run-products are invariably glassy. Nucleation is also suppressed in the latitic run-products at the three highest 13 cooling rates. Conversely, in the 0.5 and 0.125 °C/min runs, latites have a crystal content of 90 vol.%. The 14 phases are: plagioclase, clinopyroxene, glass and iron-bearing oxide (in order of abundance). The variable 15 quench temperatures, investigated by coupling experiments with Pt-wire and Pt- capsule sample containers inset 2,again did not produce crystallization of trachyte, whereas latitic samples are characterized by 10 vol.% of oxides, pyroxenes and plagioclase (in order of appearance), at temperature b1000 °C. Effects of (preferential) heterogeneous nucleation on sample holders, of superheating degree, and chemical species loss during cooling are absent for both melt compositions. The difference of solidification paths between these two silicate melts can be ascribed only to their small chemical differences. In comparison with calculated equilibrium conditions all the experimental latitic and trachytic run-products revealed strong kinetic effects, interpretable in the light of the nucleation theory. The glass- forming ability (GFA) of trachyte is higher, whereas their critical cooling rate (Rc) is lower (b0.125 °C/min), in comparison to latitic melts (RcN0.5 °C/min). The experimental results carried out in this study can be applied to lava flows and domes; trachytic lavas are able to flow for longer period with respect to latitic ones in a metastable condition. Glass-rich terrestrial lavas, i.e. obsidians, can be the result of sluggish nucleation kinetics due to the relative high polymerisation of evolved silicate melts.
    Description: Published
    Description: 91-101
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: crystallization ; lava flows ; 04. Solid Earth::04.08. Volcanology::04.08.02. Experimental volcanism ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 05. General::05.02. Data dissemination::05.02.02. Seismological data
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  • 3
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    Mechanisms for ground-surface fracturing and incipient slope failure associated with the 2001 eruption of Mt. Etna, Italy: analysis of ephemeral field data (2008)
    Elsevier
    Details
    Publication Date: 2020-11-26
    Description: During the July^August 2001 eruption of Mt. Etna development of extensional fractures/faults and grabens accompanied magma intrusion and subsequent volcanic activity. During the first days of the eruption, we performed an analysis of attitude, displacement and propagation of fractures and faults exposed on the ground surface in two sites, Torre del Filosofo and Valle del Leone, located along the same fracture system in the region surrounding the Valle del Bove depression on the eastern flank of Mt. Etna. Fractures and faults formed as the consequence of a shallow intruding dyke system that fed the several volcanic centres developed along the fracture system. The investigated sites differ in slope attitude and in geometrical relationships between fractures and slopes. In particular, the fracture system propagated parallel to the gentle slope (67‡ dip) in the Torre del Filosofo area, and perpendicular to the steep slope (V25‡ dip) in the Valle del Leone area. In the Torre del Filosofo area, slight graben subsidence and horizontal extension of the ground surface by about 3 m were recorded. In the Valle del Leone area, extensional faulting forming a larger and deeper graben with horizontal extension of the ground surface by about 10 m was recorded. For the Valle del Leone area, we assessed a downhill dip of 14‡ for the graben master fault at the structural level beneath the graben where the fault dip shallows. These results suggest that dyke intrusion at Mount Etna, and particularly in the region surrounding the Valle del Bove depression, may be at the origin of slope failure and subsequent slumps where boundary conditions, i.e. geometry of dyke, slope dip and initial shear stress, amongst others, favour incipient failures.
    Description: Published
    Description: 281-294
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.2. Tettonica attiva
    Description: 3.5. Geologia e storia dei sistemi vulcanici
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: dykes ; extensional fractures ; grabens ; slope failures ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
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  • 4
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    The effect of H2O on the viscosity of K-trachytic melts at magmatic temperatures (2007)
    Elsevier
    Details
    Publication Date: 2020-10-29
    Description: Viscosity of hydrous trachytes from the Agnano Monte Spina eruption (Phlegrean Fields, Italy) has been determined at 1.0 GPa and temperatures between 1200 and 1400 °C using the falling sphere method in a piston cylinder apparatus. The H2O content in the melts ranged from 0.18 to 5.81 wt.%. These high-temperature hydrous viscosities, along with previous ones determined at low-temperature (anhydrous and hydrous) and at high-temperature (anhydrous), at 1 atm on the same melt composition, represent the only complete viscosity data set available for K-trachyticmelts, frommagmatic to volcanic conditions.Viscosity decreases with increasing temperature andwater content in the melt.At constant temperature, viscosity appears to significantly decreasewhen the first wt.% ofH2Ois added.At H2O content higher than 3 wt.% the effect of temperature on viscosity is slight. Moreover, the deviation from Arrhenian behaviour towards greater “fragility” occurs with increasing water content. We combined low- and high-temperature viscosities (also from literature) and parameterized themby the use of a modified Vogel–Fulcher–Tamman equation, which accommodates the non-Arrhenian temperature dependence ofmelt viscosity.Moreover, in order to explore the extent to which the improved knowledge of Agnano Monte Spina trachyte viscosity may affect simulation of volcanic eruption at Phlegrean Fields, we included our viscosity models in numerical simulations of magma flow and fragmentation along volcanic conduits. These simulations show that the new parameterizations (and hence the new equations) give stronger predictions in the temperature interval relevant for magmatic and eruptive processes.
    Description: Published
    Description: 124-137
    Description: JCR Journal
    Description: reserved
    Keywords: Viscosity ; Trachyte ; Falling sphere method ; Vogel–Fulcher–Tamman equation ; 04. Solid Earth::04.08. Volcanology::04.08.02. Experimental volcanism ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
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  • 5
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    Forecasting Lava Flow Hazard during the 2006 Etna Eruption: Using the Magflow Cellular Automata Model (2008)
    Elsevier
    Details
    Publication Date: 2020-11-16
    Description: The MAGFLOW cellular automata model was able to fairly accurately reproduce the time of the lava flow advance during the 2006 Etna eruption leading to very plausible flow predictions. MAGFLOW is intended for use in emergency response situations during an eruption to quickly forecast the lava flow path over some time interval from the immediate future to a long-time forecast. Major discrepancies between the observed and simulated paths occurred in the early phase of the 2006 eruption due to an underestimation of the initial flow rate, and at the time of the overlapping with the 2004-2005 lava flow. Very good representations of the areas likely to be inundated by lava flows were obtained when we adopt a time-varying effusion rate and include the 2004-2005 lava flow field in the Digital Elevation Model (DEM) of topography.
    Description: Published
    Description: 1050-1060
    Description: 5V. Processi eruttivi e post-eruttivi
    Description: JCR Journal
    Description: open
    Keywords: Lava Flow ; Etna volcano ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.01. Computational geophysics::05.01.02. Cellular automata, fuzzy logic, genetic alghoritms, neural networks ; 05. General::05.01. Computational geophysics::05.01.05. Algorithms and implementation
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  • 6
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    Proximal tephra hazards: Recent eruption studies applied to volcanic risk in the Auckland volcanic field, New Zealand (2007)
    Elsevier
    Details
    Publication Date: 2020-11-30
    Description: Auckland, New Zealand is unique in being a metropolitan area built on an active volcanic field. Despite the small size and intensity of Auckland eruptions, the risk from tephra fall is high because of the high density of buildings and lifelines. The nature of this threat can be evaluated by comparisons with historical Strombolian and Hawaiian eruptions, which have occurred in non-populated areas. Cone-building phases of such eruptions are typically protracted, i.e., weeks to months in duration, prolonging the period during which emergency managers will have to fine tune mitigation for numerous parameters such as fluctuations in intensity and wind shifts. Rapid cone growth during future eruptions will define a region of some 30 to 100 ha where complete destruction will occur on a time scale of hours. The cost of this destruction is likely to range between NZ$200M and NZ$1.4B (ca. US$130M to US$900M). Beyond this, we have modeled the cumulative long-term effect of the build-up of a downwind blanket of lapilli and ash by estimating accumulation rates for three phases of the 1959 Kīlauea Iki eruption in Hawaii. The effect of changing wind direction was evaluated using low-level wind data from Auckland. These results show that intervals between 4 and 100 h will lapse before onset of significant damage to buildings.
    Description: Published
    Description: 138-149
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: reserved
    Keywords: tephra hazard ; Auckland volcanic field ; cone growth ; tephra fall ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 7
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    Non-Newtonian rheology of crystal-bearing magmas and implications for magma ascent dynamics (2007)
    Elsevier
    Details
    Publication Date: 2021-01-27
    Description: The eruptive dynamics of volcanic systems are largely controlled by the viscosity of deforming magma. Here we report the results of a series of high-temperature, high-pressure experiments at conditions relevant for volcanic conduits (250 MPa confining pressure and temperature between 500 °C and 900 °C) that were undertaken to investigate the rheology of magma with crystal fractions varying between 0.5 and 0.8 (50 to 80 wt.%) at different strain-rate conditions. The experiments demonstrate that the presence of crystals increases the relative viscosity (ratio between the viscosity of the mixture and the viscosity of the melt phase) of magmas and additionally induces a decrease of the relative viscosity with increasing strain-rate (shear thinning, non-Newtonian behavior). The experimental results, combined with existing data at low crystal fractions (0–0.3), were used to develop a semi-empirical parameterization that describes the variations of relative viscosity for crystal fractions between 0 and 0.8 and accounts for the complex non-Newtonian rheology of crystal-bearing magmas. The new parameterization, included into numerical models simulating the magma ascent dynamics, reveals that strain-rate-dependent rheology significantly modifies the dynamic behavior inside volcanic conduits, particularly affecting the magma fragmentation conditions.
    Description: Published
    Description: 402-419
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: partially_open
    Keywords: magma rheology ; experimental deformation ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
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  • 8
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    High-temperature viscosity measurements of hydrous albite liquid using in-situ falling sphere viscometry at 2.5 GPa (2007)
    Elsevier
    Details
    Publication Date: 2020-10-29
    Description: In-situ falling-sphere viscometry using shadow radiography in a multianvil apparatus was conducted on a series of samples along the NaAlSi3O8–H2O join up to 2.8 wt.% H2O at the Spring-8 synchrotron radiation facility (Hyogo, Japan). This allowed us to determine viscosities normally too low to be measured at ambient pressure for hydrous silicate melts at high temperatures due to rapid devolatilization. Pressure was fixed at 2.5 GPa for all experiments allowing us to gauge the effect of chemical composition on viscosity. In particular, the series of samples allowed us to vary the melt's degree of polymerization while maintaining a constant Al to Si ratio. Our results show that, for all samples, viscosity decreases as a function of pressure between 1 atm and 2.5 GPa at 1550 °C, indicating that the pressure anomaly can still be observed as depolymerization of the melt increases from nominally 0 (dry albite liquid) to NBO/T=0.8 (assuming water speciation entirely as hydroxyl groups at experimental conditions). We also find that the magnitude of the decrease in viscosity over this pressure interval does not appear to be dependent on the amount of water in the melt (i.e., NBO/T). An explanation for this behavior might be that the molar volume, at least over this limited compositional range, is nearly constant and the effects of compression of these melts, though different in degree of polymerization, are similar.
    Description: Published
    Description: 2-9
    Description: JCR Journal
    Description: reserved
    Keywords: Viscosity ; Silicate melts ; High pressure ; 04. Solid Earth::04.01. Earth Interior::04.01.05. Rheology ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
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  • 9
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    Crustal contamination and crystal entrapment during polybaric magma evolution at Mt.Somma-Vesuvius volcano, Italy: Geochemical and Sr isotope evidence (2007)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: New major and trace element analyses and Sr-isotope determinations of rocks from Mt. Somma–Vesuvius volcano produced from 25 ky BP to 1944 AD are part of an extensive database documenting the geochemical evolution of this classic region. Volcanic rocks include silica undersaturated, potassic and ultrapotassic lavas and tephras characterized by variable mineralogy and different crystal abundance, as well as by wide ranges of trace element contents and a wide span of initial Sr-isotopic compositions. Both the degree of undersaturation in silica and the crystal content increase through time, being higher in rocks produced after the eruption at 472 AD (Pollena eruption). Compositional variations have been generally thought to reflect contributions from diverse types of mantle and crust. Magma mixing is commonly invoked as a fundamental process affecting the magmas, in addition to crystal fractionation. Our assessment of geochemical and Srisotopic data indicates that compositional variability also reflects the influence of crustal contamination during magma evolution during upward migration to shallow crustal levels and/or by entrapment of crystal mush generated during previous magma storage in the crust. Using a variant of the assimilation fractional crystallization model (Energy Conservation– Assimilation Fractional Crystallization; [Spera and Bohrson, 2001. Energy-constrained open-system magmatic processes I: General model and energy-constrained assimilation and fractional crystallization (EC–AFC) formulation. J. Petrol. 999– 1018]; [Bohrson, W.A. and Spera, F.J., 2001. Energy-constrained open-system magmatic process II: application of energyconstrained assimilation–fractional crystallization (EC–AFC) model to magmatic systems. J. Petrol. 1019–1041]) we estimated the contributions from the crust and suggest that contamination by carbonate rocks that underlie the volcano (2 km down to 9–10 km) is a fundamental process controlling magma compositions at Mt. Somma–Vesuvius in the last 8 ky BP. Contamination in the mid- to upper crust occurred repeatedly, after the magma chamber waxed with influx of new mantle- and crustal-derived magmas and fluids, and waned as a result of magma withdrawal and production of large and energetic plinian and subplinian eruptions.
    Description: Published
    Description: 303– 329
    Description: reserved
    Keywords: Mt. Somma–Vesuvius volcano ; Sr isotopes ; Geochemistry ; Crustal contamination ; Mantle source ; Phenocryst entrapment ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data
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    Type: article
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  • 10
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    Seismic hazard assessment at Mt. Vesuvius: Maximum expected magnitude (2007)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: This paper deals with the problem of seismicity at Mt. Vesuvius with a view to providing an estimation of the maximum expected earthquake. Integrated analysis of both historical and current seismicity as well as the geological conditions of Vesuvius and the surrounding areas show that seismogenetic structures may fall within the crater axis and at the boundaries of the volcanic complex. While activation of the whole seismogenetic volume detected by seismicity in the past 30 years would indicate a total seismic moment of Mo = 7.1E+ 15 Nm for a magnitude M = 4.5, knowledge of the area's geological structure suggests faulting surfaces of about 32 km2 with an associated magnitude of M = 5.4. The areas of maximum expected damage differ according to the orientation of the hypothesized structure. Analysis of geological and geophysical data and the damage associated to the AD 62 earthquake shows that the prevailing directions in the faulting planes are NE–SW in the eastern sector of the volcanic complex, and roughly WNW–ESE in the southern part of the volcano along the coast. Comparison of instrumental seismicity and historical data reveals two significantly different energy levels: a lower earthquake level with Mmax = 4.5, corresponding to current seismicity and that which accompanied volcanic activity in the eruptive period from 1631–1944; an upper level with Mmax = 5.4, represented by the AD 62 earthquake. The two levels correspond to two stress states and different seismogenetic structures.
    Description: Published
    Description: 139-149
    Description: 3.6. Fisica del vulcanismo
    Description: 3.10. Sismologia storica e archeosismologia
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: 5.1. TTC - Banche dati e metodi macrosismici
    Description: JCR Journal
    Description: reserved
    Keywords: Mt. Vesuvius ; seismic hazard ; historical seismicity ; 04. Solid Earth::04.06. Seismology::04.06.05. Historical seismology ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 11
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    Hydrothermal fluid circulation and its effect on caldera unrest (2007)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: This paper focuses on the role that hydrothermal systems may play in caldera unrest. Changes in the fluid chemistry, temperature, and discharge rate of hydrothermal systems are commonly detected at the surface during volcanic unrest, as hydrothermal fluids adjust to changing subsurface conditions. Geochemical monitoring is carried out to observe the evolving system conditions. Circulating fluids can also generate signals that affect geophysical parameters monitored at the surface. Effective hazard evaluation requires a proper understanding of unrest phenomena and correct interpretation of their causes. Physical modeling of fluid circulation allows quantification of the evolution of a hydrothermal system, and hence evaluation of the potential role of hydrothermal fluids during caldera unrest. Modeling results can be compared with monitoring data, and then contribute to the interpretation of the recent caldera evolution. This paper: 1) describes the main features of hydrothermal systems; 2) briefly reviews numerical modeling of heat and fluid flow through porous media; 3) highlight the effects of hydrothermal fluids on unrest processes; and 4) describes some model applications to the Phlegrean Fields caldera. Simultaneous modeling of different independent parameters has proved to be a powerful tool for understanding caldera unrest. The results highlight the importance of comprehensive conceptual models that incorporate all the available geochemical and geophysical information, and they also stress the need for high-quality, multi-parameter monitoring and modeling of volcanic activity.
    Description: Accepted
    Description: 3.6. Fisica del vulcanismo
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: open
    Keywords: hydrothermal activity ; caldera unrest ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 12
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    Changing conditions of magma ascent and fragmentation during the Etna 122 BC basaltic Plinian eruption: Evidence from clast microtextures (2007)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The Etna 122 BC basaltic eruption had two Plinian phases, each preceded and followed by weak phreatic and phreatomagmatic activity. This study infers changing eruption dynamics from density, grain size, and microtextural data from the erupted pyroclasts. The Plinian clasts show no evidence for quenching by external water; instead, all clasts are microvesicular and have high bubble number densities relative to the products of weaker basaltic explosive eruptions, suggesting that the 122 BC magma underwent coupled degassing linked to rapid ascent and decompression. This coupled degassing was probably enhanced by crystallization of abundant microlites, which increased the magma's effective viscosity during conduit ascent. Detailed measurements of vesicles and microlites show wide variations in number densities, size distributions, and shapes among clasts collected over narrow stratigraphic intervals. For such a diversity of clasts to be expelled together, portions of melt with contrasting ascent and degassing histories must have arrived at the fragmentation surface at essentially the same time. We suggest that a parabolic velocity profile across the conduit ensured that magma near the conduit walls ascended more slowly than magma along the axis, leading to a longer residence time and more advanced degrees of outgassing and crystallization in the marginal magma. In our model, accumulation of this outgassed, viscous magma along conduit walls reduced the effective radius of the shallow conduit and led to blockages that ended the Plinian phases.
    Description: Published
    Description: 333-354
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: basaltic Plinian ; Etna ; vesicles ; microlites ; conduit dynamics ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
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  • 13
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    Volumetric observations during paroxysmal eruptions at Mount Etna: pressurized drainage of a shallow chamber or pulsed supply? (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The October 17 to November 5, 1999, eruption of Mount Etna’s Bocca Nuova crater emplaced a V15U106 m3 flow field. The eruption was characterized by 11 paroxysmal events during which intense Strombolian and lava fountain activity fed vigorous channelized PaPa flows at eruption rates of up to 120 m3 s31. Each paroxysm lasted between 75 and 450 min, and was separated by periods of less intense Strombolian activity and less vigorous (610 m3 s31) effusion. Ground-based, satellite- and model-derived volumetric data show that the eruption was characterized by two periods during which eruption rates and cumulative volume showed exponential decay. This is consistent with a scenario whereby the system was depressurized during the first eruptive period (October 17^23), repressurized during an October 24 pause, and then depressurized again during the second period (October 25^28). The imbalance between the erupted and supplied volumes mean that the two periods involved the collection of 1.5^5.7U106 m3 and 1.2^ 3.6U106 m3, respectively, or an increase in the time-averaged supply to 11.6^13.6 m3 s31 and 12.5^14.9 m3 s31. Two models are consistent with the observed episodic fountaining, derived volumetric trends and calculated volume imbalance: a magma collection model and a pulsed supply model. In the former case, depressurization of a shallow reservoir cause the observed volumetric trends and foam collapse at the reservoir roof powers fountaining. In the pulsing case, variations in magma flux account for pressurization^depressurization and supply the excess volume. Increases in rise rate and volatile flux, coupled with rapid exsolution during ascent, trigger fountaining. Limiting equations that define critical foam layer volumes and magma rise rates necessary for Hawaiian-style fountaining favor the latter model.
    Description: Published
    Description: 79-95
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.5. Geologia e storia dei sistemi vulcanici
    Description: 3.6. Fisica del vulcanismo
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: reserved
    Keywords: Etna ; lava fountaining ; eruption rates ; lava channel ; foam layers ; rise rates ; 04. Solid Earth::04.01. Earth Interior::04.01.99. General or miscellaneous ; 04. Solid Earth::04.01. Earth Interior::04.01.05. Rheology ; 04. Solid Earth::04.02. Exploration geophysics::04.02.99. General or miscellaneous ; 04. Solid Earth::04.02. Exploration geophysics::04.02.05. Downhole, radioactivity, remote sensing, and other methods ; 04. Solid Earth::04.02. Exploration geophysics::04.02.07. Instruments and techniques ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.11. Instruments and techniques ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.02. Experimental volcanism ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.04. Thermodynamics ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
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  • 14
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    Vent conditions for expected eruptions at Vesuvius (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Determining consistent sets of vent conditions for next expected eruptions at Vesuvius is crucial for the simulation of the sub-aerial processes originating the volcanic hazard and the eruption impact. Herewerefer to the expected eruptive scales and conditions defined in the frame of the EC Exploris project, and simulate the dynamics of magma ascent along the volcanic conduit for sub-steady phases of next eruptions characterized by intensities of the Violent Strombolian (VS), Sub-Plinian 2 (SP2), and Sub-Plinian 1 (SP1) scale. Sets of conditions for the simulations are determined on the basis of the bulk of knowledge on the past history of Vesuvius [Cioni, R., Bertagnini, A., Santacroce, R., Andronico, D., Explosive activity and eruption scenarios at Somma–Vesuvius (Italy): towards a new classification scheme. Journal of Volcanology and Geothermal Research, this issue.]. Volatile contents (H2O and CO2) are parameterized in order to account for the uncertainty in their expected amounts for a next eruption. In all cases the flow in the conduit is found to be choked, with velocities at the conduit exit or vent corresponding to the sonic velocity in the two-phase non-equilibrium magmatic mixture. Conduit diameters and vent mixture densities are found to display minimum overlapping between the different eruptive scales, while exit gas and particle velocities, as well as vent pressures, largely overlap. Vent diameters vary from as low as about 5 m for VS eruptions, to 35–55 m for the most violent SP1 eruption scale. Vent pressures can be as low as less than 1 MPa for the lowest volatile content employed of 2 wt.% H2O and no CO2, to 7–8 MPa for highest volatile contents of 5 wt.% H2O and 2 wt.% CO2 and large eruptive scales. Gas and particle velocities at the vent range from 100–250 m/s, with a tendency to decrease, and to increase the mechanical decoupling between the phases, with increasing eruptive scale. Except for velocities, all relevant vent quantities are more sensitive to the volatile content of the discharged magma for the highest eruptive scales considered.
    Description: Published
    Description: 359-365
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: Vesuvius ; Numerical simulations ; Vent conditions ; Volcanic hazard ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 15
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    Emergency planning and mitigation at Vesuvius: A new evidence-based approach (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Disasters from explosive volcanic eruptions are infrequent and experience in emergency planning and mitigation for such events remains limited. The need for urgently developing more robust methods for risk assessment and decision making in volcanic crises has become increasingly apparent as world populations continue to expand in areas of active explosive volcanism. Nowhere is this more challenging than at Vesuvius, Italy, with hundreds of thousands of people living on the flanks of one of the most dangerous volcanoes in the world. We describe how a new paradigm, evidence-based volcanology, has been applied in EXPLORIS to contribute to crisis planning and management for when the volcano enters its next state of unrest, as well as in long-term land-use planning. The analytical approach we adopted enumerates and quantifies all the processes and effects of the eruptive hazards of the volcano known to influence risk, a scientific challenge that combines field data on the vulnerability of the built environment and humans in past volcanic disasters with theoretical research on the state of the volcano, and including evidence from the field on previous eruptions as well as numerical simulation modelling of eruptive processes. Formal probabilistic reasoning under uncertainty and a decision analysis approach have provided the basis for the development of an event tree for a future range of eruption types with probability paths and hypothetical casualty outcomes for risk assessment. The most likely future eruption scenarios for emergency planning were derived from the event tree and elaborated upon from the geological and historical record. Modelling the impacts in these scenarios and quantifying the consequences for the circumvesuvian area provide realistic assessments for disaster planning and for showing the potential risk–benefit of mitigation measures, the main one being timely evacuation, but include for consideration protecting buildings against dilute, low dynamic pressure surges, and temporary roof supports in the most vulnerable buildings, as well as hardening infrastructure and lifelines. This innovative work suggests that risk-based methods could have an important role in crisis management at cities on volcanoes and small volcanic islands.
    Description: Published
    Description: 454-473
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: open
    Keywords: planning ; emergency ; volcano ; eruption ; mitigation ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 16
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    Sources of ground movement at Vesuvius before the AD 79 eruption: Evidence from contemporary accounts and archaeological studies (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Historical sources have recorded earthquake shocks, their effects and difficulties that local inhabitants experienced before the AD 79 Pompeii eruption. Archaeological studies pointed out the effects of such seismicity, and have also evidenced that several water crises were occurring at Pompeii in that period. Indeed numerous sources show that, at the time of eruption, and probably some time before, the civic aqueduct, having ceased to be supplied by the regional one, was out of order and that a new one was being built. Since Roman aqueducts were usually built with a recommended minimum mean slope of 20 cm/km and Pompeii's aqueduct sloped from the nearby Apennines toward the town, this slope could have been easily cancelled by uplift that occurred in the area even if this was only moderate. For the crustal deformations a volcanic origin is proposed and a point source model is used to explain the observations. Simple analysis of the available data suggests that the ground deformations were caused by a b2 km3 volumetric change at a depth of ∼8 km that happened over the course of several decades.
    Description: Published
    Description: 959–970
    Description: 5.1. TTC - Banche dati e metodi macrosismici
    Description: JCR Journal
    Description: reserved
    Keywords: Vesuvius ; ground deformation ; seismicity ; stress changes ; 04. Solid Earth::04.03. Geodesy::04.03.06. Measurements and monitoring ; 04. Solid Earth::04.06. Seismology::04.06.05. Historical seismology ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 17
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    Magma degassing and crystallization processes during eruptions of high-risk Neapolitan-volcanoes: Evidence of common equilibrium rising processes in alkaline magmas (2007)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Compositional, textural and experimental data on products from explosive and effusive eruptions of Neapolitan volcanoes (Campi Flegrei and Somma-Vesuvio) allow us to constrain degassing and fragmentation conditions during eruptions of alkaline magmas. Significant differences in compositional and textural features have been recognized between lavas, scoria and pumice resulting respectively from effusive, moderately and extremely explosive eruptions. Pumice samples have highly-vesicular glassy matrix, low microlite number density and moderate to high water content. Crystal Size Distributions (CSD) are steep with high intercept values; the narrow microlite size range indicates single nucleation event. Scoria products are characterized by moderate vesicularity and water content. They have high number density of microlites which are bimodal in size. CSD show distinct inflections that are explained as two crystal populations growing in distinct time. Lava samples generally have low vesicularities, moderate to high microcrystalline groundmass and low glass water content. The comparison between textural and compositional features of natural rocks with samples obtained by decompression experiments allows us to conclude that degassing processes during magma ascent occurs in near-equilibrium conditions even at high decompression rate. Moderate to long magma rise times, calculated in the order of a few days, produce opendegassing responsible formoderately explosive to effusive activity. Shortmagma rise times, calculated in the order of a fewhours, result in closed-system degassing that allow explosive fragmentation when the volume of growing bubble reaches a fixed threshold. Vesicularity and water content measured on matrix glass of pumice indicate that this process occurs at pressure of 10–30 MPa. In these conditions, degassing, fragmentation and in turn the eruptive style is strongly influenced by initial conditions in themagma chamber (volatile content, temperature, pressure) instead of decompression rate, in contrast with that observed for rhyolitic melts. These differences have important consequences in terms of volcanic hazards and risk. The low-viscosity alkaline magma is able tomaintain efficient degassing even during the final stage of magma ascent, favoring, in the case of closed-system, fragmentation and explosive activity.
    Description: Published
    Description: 164-181
    Description: reserved
    Keywords: Campi Flegrei and Somma-Vesuvio ; explosive eruptions ; vesiculation ; crystallization ; degassing ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 18
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    Modeling of the 2001 lava flow at Etna volcano by a Cellular Automata approach (2007)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The 2D Cellular Automata model, MAGFLOW, simulates lava flows and an algorithm based on the Monte Carlo approach solves the anisotropic flow direction problem. The model was applied to reproduce a lava flow formed during the 2001 Etna eruption. This eruption provided the opportunity to verify the ability of MAGFLOW to simulate the path of lava flows which was made possible due to the availability of the necessary data for both modeling and subsequent validation. MAGFLOW reproduced quite accurately the spread of flow. A good agreement was highlighted between the simulated and observed length on steep slopes, whereas the area covered by the lava flow tends to be overestimated. The major inconsistencies found in the comparison between simulated and observed lava flow due to neglecting the effects of ephemeral vent formation.
    Description: Published
    Description: 3.6. Fisica del vulcanismo
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: open
    Keywords: Lava flow ; Etna volcano ; Numerical simulation ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.01. Computational geophysics::05.01.02. Cellular automata, fuzzy logic, genetic alghoritms, neural networks
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  • 19
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    Halogen diffusion in a basaltic melt (2007)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The diffusion of the halogens fluorine, chlorine, and bromine was measured in a hawaiitic melt from Mt. Etna at 500 MPa and 1.0 GPa, 1250 to 1450 ºC at anhydrous conditions; the diffusion of F and Cl in the melt was also studied with about 3 wt% of dissolved water. Experiments were performed using the diffusion-couple technique in a piston cylinder. Most experiments were performed with only one halogen diffusing between the halogen-enriched and halogen-poor halves of the diffusion couple, but a few experiments with a mixture of halogens (F, Cl, Br) were also performed in order to investigate the possibility of interactions between the halogens during diffusion. Fluorine and chlorine diffusivity show a very similar behavior, slightly diverging at low temperature. Bromine diffusion is a factor of about 2 to 5 lower than the other halogens in this study. Diffusion coefficients for fluorine range between 2.3x10−11 and 1.4x10−10 m2s−1, for chlorine between 1.1x10−11 and 1.3x10−10 and for bromine between 9.4x10−12 and 6.8x10−11 m2s−1. No pressure effect was detected at the conditions investigated. In experiments involving mixed halogens, the diffusivities appear to decrease slightly (by a factor of ~ 3), and are more uniform among the three elements. However, activation energies for diffusion do not appear to differ between experiments with individual halogens or when they are all mixed together. The effect of water increases the diffusion coefficients of F and Cl by no more than a factor of 3 compared to the anhydrous melt (DF = 4.0x10−11 to 1.6x10−10 m2s−1; DCl = 3.0x10−11 to 1.9x10−10 m2s−1). Comparing our results to the diffusion coefficients of other volatiles in nominally dry basaltic melts, halogen diffusivities are about one order of magnitude lower than H2O, similar to CO2, and a factor of ~5 higher than S. The contrasting volatile diffusivities may affect the variable extent of volatile degassing upon melt depressurization and vesiculation, and can help our understanding of the compositions of rapidly grown magmatic bubbles.
    Description: NSERC Discovery grant INGV-DPC 2004-2006 Projects (V3_6 – Etna)
    Description: Published
    Description: 3570-3580
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: JCR Journal
    Description: reserved
    Keywords: Diffusion ; Halogens ; Basalt ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 20
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    Oscillation-induced mobility of flows of rock fragments with quasi-rigid plugs in rectangular channels with frictional walls: A hypothesis (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: We present here a new hypothesis to explain the high mobility of same rapid mass movements of rock fragments. We suggest that oscillations of flows with a quasi-rigid plug can result in reduction of their apparent coefficient of friction. This coefficient is computed as the ratio between drop in elevation and horizontal distance of travel. In our model, the effective friction during a downhill journey is a combination of the friction forces acting on the plug during the ascending and descending parts of its slope-normal oscillations. As a consequence of oscillations, the decreased contact with ground surface reduces the apparent coefficient of friction. Channel lateral surfaces can also support a portion of plug weight giving another contribution in the reduction of this coefficient. The support of lateral surfaces requires a relatively narrow channel such as a gully or the presence of levees whereas the reduced basal contact can be important also in larger channels that do not provide lateral support. We suggest that slope-normal oscillations are generated by ground asperities. The true coefficients of friction are larger than the apparent one because they account energetically for the oscillations that reduce basal contact. Thus we can say that our model is able to explain long runout distances as long as the energy dissipated by oscillations is accounted for by the true coefficients of friction that enter the calculations. Field and experimental investigation of the several ideas discussed in this paper constitutes important aspects of future research that will improve the understanding of granular flows mobility.
    Description: In press
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: Pyroclastic flows ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 21
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    Intrusion of eccentric dikes: The case of the 2001 eruption and its role in the dynamics of Mt. Etna volcano (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The 2001 eruption represents one of the most studied events both from volcanological and geophysical point of view on Mt. Etna. This eruption was a crucial event in the recent dynamic of the volcano, marking the passage from a period (March 1993 – June 2001) of moderate stability with slow, continuous flank sliding and contemporaneous summit eruptions, to a period (July 2001 to present) of dramatically increased flank deformations and flank eruptions. We show new GPS data and high precision relocation of seismicity in order to demonstrate the role of the 2001 intrusive phase in this change of the dynamic regime of the volcano. GPS data consist of two kinematic surveys carried out on 12 July, a few hours before the beginning of the seismic swarm, and on 17 July, just after the onset of eruptive activity. A picture of the spatial distribution of the sin-eruptive seismicity has been obtained using the HypoDD relocation algorithm based on the double-difference (DD) technique. Modeling of GPS measurements reveal a southward motion of the upper southern part of the volcano, driven by a NNW-SSE structure showing mainly left-lateral kinematics. Precise hypocenter location evidences an aseismic zone at about sea level, where the magma upraise was characterized by a much higher velocity and an abrupt westward shift, revealing the existence of a weakened or ductile zone. These results reveal how an intrusion of a dike can severely modify the shallow stress field, triggering significant flank failure. In 2001, the intrusion was driven by a weakened surface, which might correspond to a decollement plane of the portion of the volcano affected by flank instability, inducing an additional stress testified by GPS measurements and seismic data, which led to an acceleration of the sliding flanks.
    Description: In press
    Description: 1.1. TTC - Monitoraggio sismico del territorio nazionale
    Description: 1.3. TTC - Sorveglianza geodetica delle aree vulcaniche attive
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.2. Tettonica attiva
    Description: 3.5. Geologia e storia dei sistemi vulcanici
    Description: 3.6. Fisica del vulcanismo
    Description: 4.2. TTC - Scenari e mappe di pericolosità sismica
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: 4.4. Scenari e mitigazione del rischio ambientale
    Description: JCR Journal
    Description: reserved
    Keywords: Stress release ; Dike ; Volcano-tectonics ; Flank instability ; Mount Etna ; Instrumental monitoring ; 04. Solid Earth::04.01. Earth Interior::04.01.99. General or miscellaneous ; 04. Solid Earth::04.01. Earth Interior::04.01.02. Geological and geophysical evidences of deep processes ; 04. Solid Earth::04.02. Exploration geophysics::04.02.99. General or miscellaneous ; 04. Solid Earth::04.03. Geodesy::04.03.99. General or miscellaneous ; 04. Solid Earth::04.03. Geodesy::04.03.06. Measurements and monitoring ; 04. Solid Earth::04.03. Geodesy::04.03.07. Satellite geodesy ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.01. Earthquake geology and paleoseismology ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics ; 04. Solid Earth::04.06. Seismology::04.06.04. Ground motion ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.07. Tectonophysics::04.07.99. General or miscellaneous ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
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  • 22
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    Structural features of the 2007 Stromboli eruption (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: On 27 February 2007, two NE–SW and NNW–SSE dike-fed effusive vents opened to the North (at 650 and 400 m above sea level, asl) of the summit craters at Stromboli, forming a fissure parallel to the inner walls of the Sciara del Fuoco (SdF) sector collapse depression. The formation of these vents was soon followed by rapid subsidence of the summit crater area. This partly obstructed the central conduit, temporarily choking the fissure and increasing the deformation of the upper part of SdF. The reactivation of the NNW–SSE vent and the opening of a new vent located at 500 m asl, fed by a second dike, released the internal pressure and surface deformation ceased. The eruption then continued again from the 400 m vent, after a summit explosion on 15 March, until ending in early April after a progressive decrease of magma output. Repeated NE–SW dike intrusions have occurred in recent years, close to the upper SE limit of the SdF. In that zone, named Bastimento, the eruptive fractures traced the discontinuities that borders the SdF, increasing the risk of triggering new sector collapse. Whereas the NE–SW trending structures lie along the regional volcanostructural trend of the Aeolian arc through Stromboli, the NNW–SSE vents are oblique to this trend and may be controlled by the anomalous stress field within the unstable flank of the SdF. Another fundamental aspect of the 2007 eruption is the collapse of the central conduit, due to the rapid and deep magma drainage linked to the opening of the 400 m vent. The intrusion of dikes and development of flank vents during the 2007 eruption could possibly have triggered catastrophic landslides and related tsunami or eruptive paroxysms, but the opening of new effusive vents released the internal pressures, diminishing the hazard.
    Description: In press
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.2. Tettonica attiva
    Description: 3.5. Geologia e storia dei sistemi vulcanici
    Description: 3.6. Fisica del vulcanismo
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: reserved
    Keywords: 2007 Stromboli eruption ; Dike-fed vent ; Volcano-Tectonics ; Conduit collapse ; Flank instability ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.07. Tectonophysics::04.07.99. General or miscellaneous ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.07. Tectonophysics::04.07.08. Volcanic arcs ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.08. Risk::05.08.99. General or miscellaneous
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  • 23
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    An exceptional case of endogenous lava dome growth (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: During an eruption at the Bocca Nuova, one of the summit craters of Mt. Etna, in October-November 1999 a part of the crater floor near its WNW rim was uplifted to form a dome-shaped feature that consisted of older lava and pyroclastics filling the crater. This endogenous dome grew rapidly over the crater rim, thus being perched precariously over the steep outer slope of the Bocca Nuova, and near-continuous collapse of its steep flanks generated swiftly moving pyroclastic avalanches over a period of several hours. These avalanches advanced at speeds of 10-20 m s-1 and extended up to 0.7 km from their source on top of lavas emplaced immediately before. Their deposits were subsequently covered by lava flows that issued from vents below the front of the dome and from the Bocca Nuova itself. Growth of the dome was caused by the vertical intrusion of magma in the marginal W part of the crater, which deformed and uplifted previously emplaced, still hot and plastically deformable eruptive products filling the crater. The resulting avalanches had all characteristics of pyroclastic flows spawned by collapse of unstable flanks of lava domes, but in this case the magma involved was of mafic (hawaiitic) composition and would have, under normal circumstances, produced fluid lava flows. The formation of the dome and the generation of the pyroclastic avalanches owe their occurrence to the rheological properties of the eruptive products filling the crater, which were transformed into the dome, and to the morphological configuration of the Bocca Nuova and its surroundings. The density contrast between successive erupted products may also have played a role. Although events of this type are to be considered exceptional at Etna, their recurrence might represent a serious hazard to visitors to the summit area.
    Description: Published
    Description: 115-128
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: JCR Journal
    Description: reserved
    Keywords: Mt. Etna ; Bocca Nuova ; endogenous lava dome ; pyroclastic avalanches ; magma ascent ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions ; 05. General::05.08. Risk::05.08.99. General or miscellaneous
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  • 24
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    Hydrothermal Fluid Circulation and its Effect on Caldera Unrest (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: This paper focuses on the role that hydrothermal systems may play in caldera unrest. Changes in the fluid chemistry, temperature, and discharge rate of hydrothermal systems are commonly detected at the surface during volcanic unrest, as hydrothermal fluids adjust to changing subsurface conditions. Geochemical monitoring is carried out to observe the evolving system conditions. Circulating fluids can also generate signals that affect geophysical parameters monitored at the surface. Effective hazard evaluation requires a proper understanding of unrest phenomena and correct interpretation of their causes. Physical modeling of fluid circulation allows quantification of the evolution of a hydrothermal system, and hence evaluation of the potential role of hydrothermal fluids during caldera unrest. Modeling results can be compared with monitoring data, and then contribute to the interpretation of the recent caldera evolution. This paper: 1) describes the main features of hydrothermal systems; 2) briefly reviews numerical modeling of heat and fluid flow through porous media; 3) highlight the effects of hydrothermal fluids on unrest processes; and 4) describes some model applications to the Phlegrean Fields caldera. Simultaneous modeling of different independent parameters has proved to be a powerful tool for understanding caldera unrest. The results highlight the importance of comprehensive conceptual models that incorporate all the available geochemical and geophysical information, and they also stress the need for high-quality, multi-parameter monitoring and modeling of volcanic activity.
    Description: Published
    Description: 393-416
    Description: 3.6. Fisica del vulcanismo
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: reserved
    Keywords: hydrothermal fluids ; unrest ; modeling ; caldera ; monitoring ; volcanic hazard ; 03. Hydrosphere::03.04. Chemical and biological::03.04.06. Hydrothermal systems ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 25
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    Modeling the interplay of fO2 and fS2 along the FeS-silicate melt equilibrium (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: In this paper we will discuss a simplified thermodynamic description for the saturation of FeS, either liquid or solid, in magmatic melts. The Conjugated-Toop–Samis–Flood–Grjotheim model [Moretti R. and Ottonello G., 2005. Solubility and speciation of sulfur in silicate melts, the Conjugated-Toop–Samis–Flood–Grjotheim (CTSFG) model. Geochimica et Cosmochimica Acta, 69, 801–823] has furnished the theoretical reference frame, since it already accounts for the solubility of gaseous sulfur and the speciation and oxidation state of sulfur in silicate melts. We provide a new model to predict the saturation of magmatic silicate melts with an FeS phase that is internally consistent with these previous parameterizations. The derived model provides an effective sulfogeobarometer, which is superior with respect to previous models. For magmas rising from depth to surface, our appraisal of molar volumes of sulfur-bearing species in silicate melts allows us to model oxidation–reduction processes at different pressures, and sulfur concentrations for saturationwith either liquid or solid phases. In this respect, the nature of the oxygen fugacity buffer is critical. On the basis of model results on some typical compositions of volcanological interest, the sulfur contents at sulfide saturation (SCSS) have been calculated and the results duplicate the experimental observations that the SCSS is positively correlatedwith pressure forwatersaturated acidic melts and negatively correlated with pressure for water-poor basaltic melts. This new model provides fO2–fS2 pairs of FeS saturation of natural silicatemelts. In caseswhere the redox constraint is lacking, the model can be used to investigate whether the dissolved sulfur content approaches SCSS or not, and if so, to estimate at which fO2 value the silicate melt is saturated with a sulfide phase
    Description: Published
    Description: 286–298
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: Sulfur ; Silicate melt ; Iron sulfide ; Chemical thermodynamics ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.04. Thermodynamics ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks
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  • 26
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    Evaluating explosive eruption risk at European volcanoes (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: No Abstract
    Description: Published
    Description: V-IX
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: reserved
    Keywords: Rischio Vulcanico ; Exploris ; Vulcani esplosivi ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 27
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    Emplacement mechanism of gravity flows inferred fromhigh resolution Lidar data: The 1944 Somma–Vesuvius lava flow (Italy) (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: A Digital Terrain Model derived from high resolution Lidar data allows the determination of the morphometric and physical parameters of a lava flow erupted from the Somma–Vesuvius volcano in 1944. The downstream variation of morphometric parameters including slope, aspect, relative relief, thickness, width, and cross sectional area is analyzed, and the changes in viscosity, velocity and flow rate are estimated. The aims of the analyses are to recognize different flow surfaces, to reconstruct the flow kinematics, and to obtain information on the mechanism of emplacement. The results indicate that the 1944 lava flow can be divided in three sectors: a near vent sector (NVS) characterized by a toe-like surface, an intermediate sector (IS) with an ‘a’ātype brittle surface, and a distal sector (DS) with a sheet-like ductile surface. Lateral leveés and channels do not occur in NVS, whereas they are well developed in IS. In DS, leveés increase with an increasing distance from the vent. Fold-like surfaces occur in NVS and DS, reflecting local shortening processes due to a decrease in the slope of the substratum and overflows from the main channel. IS and DS emplaced between March 18 and 21, 1944, whereas NVS emplaced on March 19 and partly covered IS. The morphometric and physical parameters indicate that IS moved in a ‘tube’-like regime, whereas DS emplaced in a 'mobile crust' regime. The IS to DS transition is marked by an increase in velocity and the flow rate, and by a decrease in thickness, width, cross sectional area, and viscosity. This transition is due to an abrupt increase in the slope of the substratum. The estimated velocity values are in good agreement with the measurements during the 1944 eruption. The analysis used here may be extended to other lava flows. Some gravity flows (debris/mud flows, floods, and avalanches) have rheological properties and shapes similar to those of lavas, and the same process-form relationships may apply to these flows. The approach used here may be therefore useful for evaluating hazards from various gravity currents.
    Description: Published
    Description: 223–235
    Description: 1.10. TTC - Telerilevamento
    Description: 3.6. Fisica del vulcanismo
    Description: 5.4. TTC - Sistema Informativo Territoriale
    Description: JCR Journal
    Description: reserved
    Keywords: Lava flow ; Gravity flow ; Lidar ; Digital Terrain Model (DTM) ; 04. Solid Earth::04.04. Geology::04.04.03. Geomorphology ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
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  • 28
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    Recicling and “re-hydration” of degassed magma inducing transient dissolution/crystallization events at Stromboli (Italy) (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Intrusive degassing and recycling of degassed and dense magma at depth have been proposed for a long time at Stromboli. The brief explosive event that occurred at the summit craters on 9 January 2005 threw out bombs and lapilli that could be good candidates to illustrate recycling of shallow degassed magma at depth. We present an extensive data set on both the textures and the mineral, bulk rock and glassy matrix chemistry of the “9 Jan” products. The latter have the common shoshonitic–basaltic bulk composition of lavas and scoriae issued from typical strombolian activity. In contrast they differ by the heterogeneous chemistry of their matrix glasses and their crystal textures that testify to crystal dissolution event(s) just prior magma crystallization upon ascent and eruption. Comparison between mineral paragenesis of the natural products and experimental phase equilibria suggest water-induced magma re-equilibration. We propose that mineral dissolution is related to water enrichment of the recycled degassed magma, via differential gas bubble transfer and to some extents its physical mixing with volatile-rich magma blobs. However, all these features illustrate transient processes. Even though evidence of mineral dissolution is ubiquitous at Stromboli, its effect on the bulk magma chemistry is minor because of the subtle interplay between mineral dissolution and crystallization in magmas having comparable bulk chemistry.
    Description: Published
    Description: 325-336
    Description: JCR Journal
    Description: reserved
    Keywords: mineral dissolution ; magma chemistry ; volatiles ; trace elements ; Stromboli ; 04. Solid Earth::04.04. Geology::04.04.05. Mineralogy and petrology ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 29
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    Cyclical slope instability and volcanism related to volcano-tectonism in resurgent calderas: The Ischia island (Italy) case study (2007)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The results of a detailed stratigraphic study, carried out in the areas located to the east and south-west of Mt. Epomeo at Ischia, are presented and compared with those of previous geological, archaeological and historical investigations to show the relationships among caldera resurgence, volcanism and slope instability in the past 5.5 ka. Resurgence at Ischia began at about 30 ka B.P. and occurred through intermittent uplifting and tectonic quietness phases. During the past 5.5 ka reactivation of faults and related volcanic activity was accompanied by emplacement of deposits generated by surface gravitational movements. These deposits were generated in four main phases, dated between 5.5 and 2.9 ka, around 2.9 ka, between 2.6 and 2.3 ka, and between 2.3 and 1.9 ka, respectively. Deposits formed by gravitational movements preceded and followed the emplacement of volcanic rocks, testifying that slope instability was induced by vertical movements, which also activated and/or reactivated faults and fractures that fed volcanism. The results of this study therefore suggest that, although slope failure can occur as a consequence of a variety of factors, resurgence has to be considered a factor inducing a particularly intense slope instability. Resurgence is accompanied by activation of faults and renewal of volcanism, causing oversteepening of the slopes and generating seismicity that could trigger surface gravitational movements. Furthermore, the availability of large amount of loose material, rapidly accumulated along the slopes during eruptions, favors landslide generation.
    Description: Published
    Description: 148–165
    Description: reserved
    Keywords: Slope instability ; Volcanism ; Volcano-tectonism ; Resurgent calderas ; Ischia ; 04. Solid Earth::04.04. Geology::04.04.03. Geomorphology ; 04. Solid Earth::04.04. Geology::04.04.10. Stratigraphy ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 30
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    Modeling of the steady-state temperature field in lava flows lévees (2007)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The rationale of lava flow deviation is to prevent major damage, and, among the possible techniques, the opening of the flow leve¤es has often been demonstrated to be suitable and reliable. The best way to open the leve¤es in the right point, in order to obtain the required effect, is to produce an explosion in situ, and it is then necessary to map with the highest precision the temperature field inside the leve¤es, in order to design a safe and successful intervention. The leve¤es are formed by lava flows due to their non-Newtonian rheology, where the shear stress is lower than the yield stress. The leve¤es then cool and solidify due to heat loss into the atmosphere. In this work we present analytical solutions of the steady-state heat conduction problem in a leve¤e using the method of conformal mapping for simple geometrical shapes of the levee cross-section (triangular or square). Numerical solutions are obtained with a finite element code for more complex, realistic geometries.
    Description: Published
    Description: 241-251
    Description: open
    Keywords: steady-state temperature ; lava flow ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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    Type: article
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  • 31
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    The Magma feeding system of Somma-Vesuvius (Italy)strato-volcano:new inferences from a review of geochemical and Sr,Nd,Pb and O isotope data. Volcanism in the Campania Plain: Vesuvius, Campi Flegrei and Ignimbrites (2007)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: A large database of major, trace and isotope (Sr, Nd, Pb, O) data exists for rocks produced by the volcanic activity of Somma-Vesuvius volcano. Variation diagrams strongly suggest a major role for evolutionary processes such as fractional crystallization, contamination, crystal trapping and magma mixing, occurring after magma genesis in the mantle. Most mafic magmas are enriched in LILE (K, Rb, Ba), REE (Ce, Sm) and Y, show small Nb–Ta negative anomalies, and have values of Nb/Zr at about 0.15. Enrichments in LILE, REE, Nb and Ta do not correlate with Sr isotope values or degree of both K enrichment and silica undersaturation. The results indicate mantle source heterogeneity produced by slab-derived components beneath the volcano. However, the Sr isotope values of Somma-Vesuvius increase from 0.7071 up to 0.7081 with transport through the uppermost 11–12 km of the crust. The Sr isotope variation suggests that the crustal component affected the magmas during ascent through the lithosphere to the surface. Our new geochemical assessment based on chemical, isotopic and fluid inclusion data points to the existence of three main levels of magma storage. Two of the levels are deep and may represent long-lived reservoirs, and an uppermost crustal level that probably coincides with the volcanic conduit. The deeper level of magma storage is deeper than 12 km and fed the 1944 AD eruption. The intermediate level coincides with the seismic discontinuity detected by Zollo et al. (1996) at about 8 km. This intermediate level supplies magmas with 87Sr/86Sr values between 0.7071 and 0.7074, and δO18 8‰ that typically erupted both during interplinian (i.e. 1906 AD) and sub-plinian (472 AD, 1631 AD) events. The shallowest level of magma storage at about 5 km was the site of magma chambers for the Pompei and Avellino eruptions. New investigations are necessary to verify the proposed magma feeding system.
    Description: Published
    Description: 183-204
    Description: open
    Keywords: NONE ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data
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    Type: book chapter
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  • 32
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    Time-dependent geochemistry of clinopyroxene from Alban Hills (Central Italy): clues to source and evolution of ultrapotassic magmas. (2007)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: We investigated chemical and isotopic compositions of clinopyroxene crystals from well age-constrained juvenile scoria clasts, lava flows, and hypoabyssal magmatic ejecta representative of the whole eruptive history of the Alban Hills Volcanic District. The Alban Hills is a Quaternary ultra-potassic district that was emplaced into thick limestone units along the Tyrrhenian margin of Italy. Alban Hills volcanic products, even the most differentiated, are characterised by low SiO2 content. We suggest that the low silica activity in evolving magmas can be ultimately due to a decarbonation process occurring at the magma/limestone interface. According to the liquid line of descent we propose, the differentiation process is driven by crystallisation of clinopyroxene+leuciteFapatiteFmagnetite coupled with assimilation of a small amount of calcite and/or with interaction with crustal CO2. By combining age, chemical data, strontium and oxygen isotopic compositions, and REE content of clinopyroxene, we give insights into the evolution of primitive ultrapotassic magmas of the Alban Hills Volcanic District over an elapsed period of about 600 kyr. Geochemical features of clinopyroxene crystals, consistent with data coming from other Italian ultrapotassic magmas, indicate that Alban Hills primary magmas were generated from a metasomatized lithospheric mantle source. In addition, our study shows that the 87Sr / 86Sr and LREE/HREE of Alban Hills magmas continuously diminished during the 600–35 ka time interval of the Alban Hills eruptive history, possibly reflecting the progressive depletion of the metasomatized mantle source of magmas.
    Description: Published
    Description: 330–346
    Description: JCR Journal
    Description: reserved
    Keywords: Clinopyroxene ; 87Sr / 86Sr ; REE ; Ultrapotassic rocks ; Alban Hills ; 04. Solid Earth::04.01. Earth Interior::04.01.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
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  • 33
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    Magma-carbonate interaction: an experimental study on ultrapotassic rocks (2007)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The Alban Hills ultrapotassic volcanic district is one of the main districts emplaced during Quaternary time along the Tyrrhenian margin of Italy. Alban Hills lava flows and scoria clasts are made up essentially of clinopyroxenes and leucites and their chemical composition is mostly K-foiditic. Differentiated products (MgO〈3 wt%) are characterized by low SiO2 concentration (〈50 wt%) and geochemical features indicate that this unique differentiation trend is driven by crystal fractionation plus carbonate crust interaction. Notably, the Alban Hills Volcanic District was emplaced into thick limestone units. With the aim of constraining the magmatic differentiation, we performed experiments on the Alban Hills parental composition (plagioclase-free phono-tephrite) under anhydrous, hydrous, and hydrous-carbonated conditions. Experiments were carried out at 1 atm, 0.5 GPa and 1 GPa, temperatures ranging from 1050 to 1300 °C, and H2O and CaCO3 in the starting material up to 2 and 7 wt%, respectively. The experiments performed at 0.5 GPa resulted to be the most representative of the Alban Hills plumbing system. Clinopyroxene and leucite are the main phases occurring under all the investigated conditions and the liquidus phases. Nevertheless, our experimental results demonstrate that the occurrence of CaCO3 in the starting material strongly affects phase relations. Experiments performed under hydrous conditions crystallize magnetite and phlogopite at relatively high temperature. This early crystallization drives the glass composition towards a silica enrichment, resulting in a differentiation trend moving from phono-tephritic (Alban Hills parental composition) to phonolitic compositions. This is in contrast with micro-textural evidences showing late crystallization of magnetite and phlogopite in the natural products and with the composition of the juvenile products. On the contrary, in the CaCO3-bearing experiments (i.e., simulating magma-carbonate interaction) the magnetite and phlogopite stability fields are strongly reduced. As a consequence, the melt differentiation is mainly controlled by the cotectic crystallization of clinopyroxene and leucite, resulting in a differentiation trend moving towards K-foiditic compositions. These experimental results are in agreement with micro-textural features and chemical compositions of Alban Hills natural products and with the magmatic differentiation model inferred by geochemical data. Magma-carbonate interaction is not a rare process and its occurrence has been demonstrated for different plumbing systems. However, the uniqueness of the Alban Hills liquid line of descent suggests that the efficacy of the carbonate contamination process is controlled by different factors, the dynamics of the plumbing system being one of the most important.
    Description: INGV-DPC Project V3_1 Colli Albani Project FIRB MIUR “Development of innovative technologies for the environmental protection from natural events”.
    Description: Published
    Description: On line First
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: JCR Journal
    Description: reserved
    Keywords: Alban Hills ; ultrapotassic rocks ; experimental petrology ; magma-carbonate interaction ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
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  • 34
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    Earthen barriers to control lava £ows in the 2001 eruption of Mt. Etna (2007)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Preceded by four days of intense seismicity and marked ground deformation, a new eruption of Mt. Etna started on 17 July and lasted until 9 August 2001. It produced lava emission and strombolian and phreatomagmatic activity from four different main vents located on a complex fracture system extendingfrom the southeast summit cone for about 4.5 km southwards, from 3000 to 2100 m elevation (a.s.l.). The lava emitted from the lowest vent cut up an important road on the volcano and destroyed other rural roads and a few isolated country houses. Its front descended southwards to about 4 km distance from the villages of Nicolosi and Belpasso. A plan of intervention, including diversion and retainingbarriers and possibly lava flow interruption, was prepared but not activated because the flow front stopped as a consequence of a decrease in the effusion rate. Extensive interventions were carried out in order to protect some important tourist facilities of the Sapienza and Mts. Silvestri zones (1900 m elevation) from being destroyed by the lava emitted from vents located at 2700 m and 2550 m elevation. Thirteen earthen barriers (with a maximum length of 370 m, height of 10^12 m, base width of 15 m and volume of 25 000 m3) were built to divert the lava flow away from the facilities towards a path implyingconsiderably less damage. Most of the barriers were oriented diagonally (110^135‡) to the direction of the flow. They were made of loose material excavated nearby and worked very nicely, resistingthe thrust of the lava without any difficulty. After the interventions carried out on Mt. Etna in 1983 and in 1991^1992, those of 2001 confirm that earthen barriers can be very effective in controlling lava flows.
    Description: Elsevier
    Description: Published
    Description: 231-243
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: JCR Journal
    Description: reserved
    Keywords: lava flow control; earthen barriers; Mt; Etna 2001 eruption ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 35
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    Dike propagation in volcanic edifices: Overview and possible developments (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Eruptions are often fed by dikes; therefore, better knowledge of dike propagation is necessary to improve our understanding of how magma is transferred and extruded at volcanoes. This study presents an overview of dike patterns and the factors controlling dike propagation within volcanic edifices. Largely based on published data, three main types of dikes (regional, circumferential and radial) are illustrated and discussed. Dike pattern data from 25 volcanic edifices in different settings are compared to derive semi-quantitative relationships between the topography (relief, shape, height, and presence of sector collapses) of the volcano, tectonic setting (presence of a regional stress field), and mean composition (SiO2 content). The overview demonstrates how dike propagation in a volcano is not a random process; rather, it depends from the following factors (listed in order of importance): the presence of relief, the shape of the edifice and regional tectonic control. We find that taller volcanoes develop longer radial dikes, whose (mainly lateral) propagation is independent of the composition of magma or the aspect ratio of the edifice. Future research, starting from these preliminary evaluations, should be devoted to identifying dike propagation paths and likely locations of vent formation at specific volcanoes, to better aid hazards assessment.
    Description: In press
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.2. Tettonica attiva
    Description: 3.5. Geologia e storia dei sistemi vulcanici
    Description: 3.6. Fisica del vulcanismo
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: open
    Keywords: dikes ; volcanoes ; topography ; tectonic setting ; eruptions ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.07. Tectonophysics::04.07.99. General or miscellaneous ; 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
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  • 36
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    Ash fallout scenarios at Vesuvius: Numerical simulations and implications for hazard assessment (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Volcanic ash fallout subsequent to a possible renewal of the Vesuvius activity represents a serious threat to the highly urbanized area around the volcano. In order to assess the relative hazard we consider three different possible scenarios such as those following Plinian, Sub-Plinian, and violent Strombolian eruptions. Reference eruptions for each scenario are similar to the 79 AD (Pompeii), the 1631 AD (or 472 AD) and the 1944 AD Vesuvius events, respectively. Fallout deposits for the first two scenarios are modeled using HAZMAP, a model based on a semi-analytical solution of the 2D advection–diffusion–sedimentation equation. In contrast, fallout following a violent Strombolian event is modeled by means of FALL3D, a numerical model based on the solution of the full 3D advection–diffusion–sedimentation equation which is valid also within the atmospheric boundary layer. Inputs for models are total erupted mass, eruption column height, bulk grain-size, bulk component distribution, and a statistical set of wind profiles obtained by the NCEP/NCAR re-analysis. We computed ground load probability maps for different ash loadings. In the case of a Sub-Plinian scenario, the most representative tephra loading maps in 16 cardinal directions were also calculated. The probability maps obtained for the different scenarios are aimed to give support to the risk mitigation strategies.
    Description: Published
    Description: 366–377
    Description: 3.6. Fisica del vulcanismo
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: reserved
    Keywords: volcanic ash fallout ; volcanic hazard ; computer model ; Vesuvius ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.01. Computational geophysics::05.01.99. General or miscellaneous
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  • 37
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    Elemental and isotope covariation of noble gases in mineral phases from Etnean volcanics erupted during 2001–2005, and genetic relation with peripheral gas discharges (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: During 2001–2005, Mount Etna was characterized by intense eruptive activity involving the emission of petrologically different products from several vents, which involved at least two types of magma with different degrees of evolution. We investigated the ratios and abundances for noble-gas isotopes in fluid inclusions trapped in olivines and pyroxenes in the erupted products. We confirm that olivine has the most efficient crystalline structure for preserving the pristine composition of entrapped gases, while pyroxene can suffer diffusive He loss. Both the minerals also experience noble gas air contamination after eruption. Helium isotopes of the products genetically linked to the two different magmas fall in the isotopic range typical of the Etnean volcanism. This result is compatible with the metasomatic process that the Etnean mantle is undergoing by fluids from the Ionian slab during the last ten kyr, as previously inferred by isotope and trace element geochemistry. Significant differences were also observed among olivines of the same parental magma that erupted throughout 2001–2005, with 3He/4He ratios moving from about 7.0 Ra in 2001 volcanites, to 6.6 Ra in 2004–2005 products. Changes in He abundances and isotope ratios were attributed to variations in protracted degassing of the same magma bodies from the 2001 to the 2004–2005 events, with the latter lacking any contribution of undegassed magma. The decrease in 3He/4He is similar to that found from measurements carried out every fifteen days during the same period in gases discharged at the periphery of the volcano. To our knowledge this is the first time that such a comparison has been performed so in detail, and provides strong evidence of the real-time feeding of peripheral emissions by magmatic degassing.
    Description: Published
    Description: 683-690
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: JCR Journal
    Description: open
    Keywords: fluid inclusions ; noble gases ; helium isotopes ; magma degassing ; olivine ; pyroxene ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data
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  • 38
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    Shifting styles of basaltic explosive activity during the 2002-03 eruption of Mt. Etna, Italy (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The 2002–03 flank eruption of Etna was characterized by two months of explosive activity that produced copious ash fallout, constituting a major source of hazard and damage over all eastern Sicily. Most of the tephra were erupted from vents at 2750 and 2800 m elevation on the S flank of the volcano, where different eruptive styles alternated. The dominant style of explosive activity consisted of discrete to pulsing magma jets mounted by wide ash plumes, which we refer to as ash-rich jets and plumes. Similarly, ash-rich explosive activity was also briefly observed during the 2001 flank eruption of Etna, but is otherwise fairly uncommon in the recent history of Etna. Here, we describe the features of the 2002–03 explosive activity and compare it with the 2001 eruption in order to characterize ash-rich jets and plumes and their transition with other eruptive styles, including Strombolian and ash explosions, mainly through chemical, componentry and morphology investigations of erupted ash. Past models explain the transition between different styles of basaltic explosive activity only in terms of flow conditions of gas and liquid. Our findings suggest that the abundant presence of a solid phase (microlites) may also control vent degassing and consequent magma fragmentation and eruptive style. In fact, in contrast with the Strombolian or Hawaiian microlite-poor, fluidal, sideromelane clasts, ash-rich jets and plumes produce crystal-rich tachylite clasts with evidence of brittle fragmentation, suggesting that high groundmass crystallinity of the very top part of the magma column may reduce bubble movement while increasing fragmentation efficiency.
    Description: In press
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: Etna ; basaltic explosive activity ; ash-rich jet and plume ; tachylite ; sideromelane ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 39
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    Methana, the westernmost active volcanic system of the south Aegean arc (Greece): insight from fluids geochemistry (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: An extensive geochemical survey of the fluids released by the volcanic/geothermal system of Methana was undertaken. Gases were characterized based on the chemical and isotopic [helium (He) and carbon (C)] analysis of 27 samples. Carbon dioxide soil gas concentration and fluxes were measured at 179 sampling sites throughout the peninsula. Forty samples of thermal and cold groundwaters were also sampled and analysed to characterize the geochemistry of the aquifers. Gases of hydrothermal origin gave a preliminary geothermometric estimate of about 210 °C. The He-isotope composition indicated mantle contributions of up to 40%, and the C-isotope composition of CO2 indicated that it predominantly (〉90%) originated from limestone decomposition. The groundwater composition was suggestive of mixing between meteoric and hydrothermally modified sea-water endmembers and water–rock interaction processes limited to simple rock dissolution driven by an increased endogenous CO2 content. All of the thermal manifestations and anomalous degassing areas, although of limited extent, were spatially correlated with the main active tectonic system of the area. The total CO2 output of the volcanic system has been preliminary estimated to be less than 0.05 kg s–1. Although this value is very low compared to those of other volcanic systems, anomalous CO2 degassing at Methana – which is currently restricted to limited areas and at present is the only volcanic risk of the peninsula – is a potential gas hazard that warrants further assessment in future studies.
    Description: Published
    Description: 818-828
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Methana ; south Aegean volcanic arc ; fluids geochemistry ; soil gases ; groundwaters ; 03. Hydrosphere::03.04. Chemical and biological::03.04.03. Chemistry of waters ; 03. Hydrosphere::03.04. Chemical and biological::03.04.05. Gases ; 03. Hydrosphere::03.04. Chemical and biological::03.04.06. Hydrothermal systems ; 04. Solid Earth::04.02. Exploration geophysics::04.02.01. Geochemical exploration ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 40
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    Volcanic risk perception of young people in the urban areas of Vesuvius: Comparisons with other volcanic areas and implications for emergency management (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: More than 600000 people are exposed to volcanic risk in the urban areas near the volcano,Vesuvius, and may need to be evacuated if there is renewed volcanic activity. The success of a future evacuation will strongly depend on the level of risk perception and preparedness of the at-risk communities during the current period of quiescence. The volcanic risk perception and preparedness of young people is of particular importance because hazard education programs in schools have been shown to increase the clarity of risk perception and students often share their knowledge with their parents. In order to evaluate young people's risk perception and preparedness for a volcanic crisis, a multiple choice questionnaire was distributed to 400 high-school students in three municipalities located close to the volcano. The overall results suggest that despite a 60-year period of quiescence at Vesuvius, the interviewed students have an accurate perception of the level of volcanic risk. On the other hand, the respondents demonstrate a clear lack of understanding of volcanic processes and their related hazards.Also, the interviewed students show high levels of fear, poor perceived ability to protect themselves from the effects of a future eruption, and insufficient knowledge of the National Emergency Plan for Vesuvian Area (NEPVA). The latter result suggests that in comparisonwith volcanic crises in other regions, during a future eruption ofVesuvius, theremay not be enough time to educate the large number of people living near the volcano about how to appropriately respond. The inadequate risk education and preparedness of respondents implies that a strong effort is needed to improve communication strategies in order to facilitate successful evacuations. Therefore, it is important to take advantage of the present period of quiescence at Vesuvius to improve the accuracy of risk perception of youth in local communities.
    Description: Published
    Description: 229-243
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: reserved
    Keywords: risk perception ; disasters ; evacuation plan ; Vesuvius ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 41
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    S–Cl–F degassing pattern of water-rich alkali basalt: Modelling and relationship with eruption styles on Mount Etna volcano (2007)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Our knowledge of the degassing pattern of sulphur, chlorine and fluorine during ascent and eruption of basaltic magmas is still fragmental and mainly limited to water-poor basalts. Here we model and discuss the pressure-related degassing behaviour of S, Cl and F during ascent, differentiation and extrusion of H2O–CO2-rich alkali basalt on Mount Etna (Sicily) as a function of eruptive styles. Our modelling is based on published and new melt inclusion data for dissolved volatiles (CO2, H2O, S, Cl, F) in quenched explosive products from both central conduit (1989–2001) and lateral dyke (2001 and 2002) eruptions. Pressures are obtained from the dissolved H2O and CO2 concentrations, and vapour–melt partition coefficients of S, Cl and F are derived from best fitting of melt inclusion data for each step of magma evolution. This allows us to compute the compositional evolution of the gas phase during either open or closed system degassing and to compare it with the measured composition of emitted gases. We find that sulphur, chlorine and fluorine begin to exsolve at respective pressures of ∼140 MPa, ∼100 MPa and ≤10 MPa during Etna basalt ascent and are respectively degassed at 〉95%, 22–55%, and ∼15% upon eruption. Pure open system degassing fails to explain gas compositions measured during either lateral dyke or central conduit eruptions. Instead, closed-system ascent and eruption of the volatile-rich basaltic melt well accounts for the time-averaged gas composition measured during 2002-type lateral dyke eruptions (S/Cl molar ratio of 5±1, 35% bulk Cl loss). Extensive magma fragmentation during the most energetic fountaining phases enhances Cl release (55%) and produces a lower S/Cl ratio of 3.7, as actually measured. Comparatively slower magma rise in the central conduits of Etna favours both sulphide saturation of the melt and greater chlorine release (55%), resulting in a distinct S/Cl evolution path and final ratio in eruptive gas. In both eruption types, any previous bubble–melt separation at depth leads to increased S/Cl and S/F ratios in emitted gas. High S/Cl ratios measured during some discrete eruptive events can thus be explained by transitions from closed (deep) to open (shallow) system degassing, with differential gas transfer extending down to ∼2 km depth below the vents. This depth coincides with the base of the volcanic pile where structural discontinuities and the high magma vesicularity (60%) may favour separate gas flow. Finally, the excess S–Cl–F gas discharge through Etna summit craters during non-eruptive periods requires a mixed supply from shallow magma degassing in the volcanic conduits and deeper-derived SO2-rich bubbles from the sub-volcano plumbing system. Our modelling provides a useful reference framework for interpreting the monitored variations of S, Cl and F in Mount Etna gas emissions as a function of volcanic activity. More broadly, the observations made for S, Cl and F degassing on Etna may apply to other basaltic volcanoes with water-rich magmas, such as in arcs.
    Description: Published
    Description: 772-786
    Description: reserved
    Keywords: Mt Etna ; volatiles ; magma degassing ; eruptive mechanisms ; modelling ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
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  • 42
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    The Somma-Vesuvius volcano (Southern Italy): Structure, dynamics and hazard evaluation (2007)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: We review the main results, with several new analyses, obtained in recent times about the structure, present dynamics and hazard evaluation at Somma–Vesuvius volcanic complex. We present a global review and interpretation of structural features, both at local and regional scale, constrained both by seismic and petrological data. The local structure of Somma–Vesuvius is reviewed in three depth ranges, shallow, intermediate and deep. The shallow velocity structure is inferred by the joint inversion of shot and local earthquake arrival time data. The main feature pointed out at shallow depth is a high velocity anomaly at the crater axis, extending down to about 5 km of depth. Such an anomaly, first observed at Vesuvius, seems to be common to many other volcanoes. It can be interpreted in terms of the presence of solidified residual magma in the shallow conduits, accumulated in last eruptive cycles. The local seismicity is strongly clustered around this anomaly, due to the focusing effect of the rigidity contrast. The seismic occurrence appears as a result of the superposition of a background level, mainly due to gravitational instability of the Vesuvius cone, and of intense activity episodes, which possibly reflect episodic internal activity. Two main zones of magma accumulation in the upper crust are evidenced by the joint interpretation of seismic and petrological data. The first one, located in the depth range 4–6 km, is mainly constrained by the crystallisation depth of phonolitic magmas which fed Plinian and sub-Plinian eruptions; the second one, around 11–15 km of depth, is mainly constrained by reflected–converted seismic waves, and in agreement with crystallization depths inferred for the moderate eruptions. The study of the deep structure, performed by regional tomography with teleseisms, further points out magma roots at higher depths (15–30 km). An additional result for the deep structure, studied at regional scale and very important for geodynamic interpretations of the Tyrrhenian volcanisms, has been the evidence for a subducting slab under the Apennines, in an area where previous models hypothesised a slab window. New original studies of crystal growth (phenocrystals and microlites) on the eruptive products allow to infer typical times of magma rising from such reservoirs, which appear very low, on the order of minutes to tens of minutes. Static deformation at this volcano, in the last 30 yr, has been detected by the joint use of levelling, GPS and DIFSAR techniques. It indicates subsidence, very concentrated in the crater area and in a narrow strip all around the volcanic edifice, with maximum rates less than 0.01 m/yr. Static deformation in the crater area appears in agreement with the mechanism of gravitational instability generating local volcanotectonic seismicity, while the peculiar pattern around the volcanic edifice is probably due to the combination of extensional stress and volcanic loading, generating a ring normal fault-like structure. While the key results about structure and dynamics help to define pre-eruptive scenarios, a new probabilistic procedure to combine volcanological data and computer simulations has been used, in this paper, to build hazard maps giving the probability, at each location in the area, to be hit by a pyroclastic flow or to experience a destructive fall-out deposit. The review and new results of this work give then the first complete picture of the state of the art in our knowledge about Somma–Vesuvius volcano.
    Description: Published
    Description: 73-111
    Description: reserved
    Keywords: volcano structure ; volcano dynamics ; volcanic hazard ; Mount Vesuvius ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 43
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    Textural effects of steady state behaviour of the Stromboli feeding system (2007)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The exceptionally persistent activity of Stromboli volcano has lasted for at least 1400 years. The normal strombolian activity is periodically interrupted by more energetic explosions (1–2 per year) and by sporadic effusive episodes (every 10–20 years). Normal activity and effusive episodes are characterized by crystal-rich high-K to shoshonitic basalts issuing from a volatile-poor shallow system. Crystal-poor pumice are emitted only during more violent explosions, and are thought to derive from deep pulses of volatile-rich magma. Shallow level degassing induces massive crystallization of deep pulses of feeding magma that, continuously mixing with the resident one, produces the crystal-rich shoshonite of the persistent activity. We examined the crystallization history of the crystal-rich, shallow reservoir using plagioclase Crystal Size Distribution (CSD) analysis of scoriae and lavas emitted in the past twenty years. CSDs show a linear dependence from crystal size in the size interval 0.06–1.2 mm; number density of larger crystals is biased by right hand truncation effects. CSDs slopes and intercepts are quite constant during the whole considered time span revealing a system that is close to the equilibrium also from a kinetic point of view. The linear crystal size distribution are reached by the system through episodes of growth and resorption, respectively occurring in the degassed and undegassed magma during the continuous mixing in the feeding system. Plagioclase net growth rate (2*10−11 cm/s) results from a balance of growth (10−10 cm/s) and resorption episodes which induce spectacular zoning and resorption textures in crystals larger than 200 μm. CSDs of mafic phases cannot be accurately acquired on each single sample due to poor counting statistics; the evaluation of pyroxene and olivine CSD on the whole data set, however, confirms the conclusions acquired from plagioclase CSDs.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: crystal size distribution ; plagioclase growth ; magma residence time ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
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  • 44
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    Enclaves provide new insights on the dynamics of magma mingling: a case study from Salina Island (Southern Tyrrhenian Sea, Italy) (2007)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Three lava flows (hereafter, flows A, B, and C) from Salina Island (Italy) consist of basaltic andesitic enclaves dispersed in a dacitic matrix. Enclaves represent 8–12 vol.% of the erupted magma. The number of enclaves and the surface covered by the enclaves at each outcrop do not vary significantly with the distance from the vent in the flows A and B. These feature reflect the dynamics of magma mingling within the reservoir and not the kinematics of the lava flow. In the flow C, these parameters vary irregularly. The statistical entropy S(t) of the enclaves, which is a measure of their spatial distribution (dispersion), is estimated in outcrops located at different distance from the vent. The Kolmogorov–Sinai entropy rate k, which describes the variations of S(t) with time, is also determined. In the lava flow A, S(t) increases linearly with time t for 0btb0.4; k is 0.04. For tN0.5, S(t) attains its maximum value and maintains constant with increasing t. In the lava flow B, S(t) linearly increases with t, and k is 0.01. In the lava flow C, there is not correlation between S(t) and t. The comparison between the results from the analysis of the Porri enclaves and those from numerical experiments on the variation of S(t) in chaotic advective mixing systems and from previous experimental models on magma mixing, allow us to draw some conclusions on dynamics of the basaltic andesite– dacite mingling in the magma chamber. Fully chaotic magma mingling systems show three evolution stages. An initial stage, which is unknown because of the disruption of the initial configuration of the interacting magmas, a second stage characterized by a linear increase of the statistical entropy with time, and a third stage, in which the uniformity of the system is reached, and the entropy does not vary with increasing time. A system in which the uniformity is never attained, is characterized by irregular variations of S(t) with time. In the flows A and B, the relations between S(t) and t are consistent with those of a fully chaotic dynamics possibly associated to convection. The basaltic andesite was uniformly distributed in the dacitic host due to the occurrence of convective movements driven by the injection of the basaltic andesite within the dacitic chamber. The mingling system recorded by the lava flow A evolved with a higher rate with respect to that of the flow B. This suggests that chaotic advection (stirring and folding) is more efficient in the magmatic system A than in B. On the contrary, the mingling system C is characterized by a non-uniform distribution of the basaltic andesite within dacite. This reflects the occurrence of a dynamics in which stirring and folding processes do not operate efficiently and are unable to uniformly distribute the dispersed phase within the continuous one. The decrease of k from A to B, and the lack of a measurable k in C, along with the observation that A and B were emitted before C, indicate that the efficiency of advective movements within the Porri magma chamber declined with decreasing time. Mingled magmas characterized by a homogeneous spatial distribution of enclaves or an initially inhomogeneous distribution evolving towards a homogeneous one are indicative of efficient advection processes that may favor magma mixing. Mingled magmas characterized by an inhomogeneous distribution of enclaves suggest low dynamical interaction between the two end-members. Magma mixing is not allowed.
    Description: Published
    Description: 128–140
    Description: JCR Journal
    Description: reserved
    Keywords: volcanology ; petrology ; magma mingling ; enclaves ; lava flows ; entropy ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
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  • 45
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    The December 2002–July 2003 effusive event at Stromboli volcano, Italy: Insights into the shallow plumbing system by petrochemical studies (2007)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: On 28 December 2002, the persistent Strombolian activity at Stromboli was interrupted by the sudden onset of lava emission onto the Sciara del Fuoco slope, a horseshoe-shaped depression on the NW flank of the volcano. The effusive episode went on until 22 July 2003 and produced a cumulative volume of lavas of 11×106 m3 ranking the event as the largest occurred in the past 30 years. The eruptive vents were mainly located in the NE sector of the Sciara del Fuoco depression, at an elevation of 550–600 m a.s.l. On 30 December, the eastern portion of the Sciara del Fuoco collapsed producing a tsunamigenic landslide. On 5 April 2003, a paroxysmal eruption occurred at the summit craters during which crystal-poor pumiceous products were emitted. The paroxysm did not interrupt the lava emission. The Strombolian activity at the summit craters gradually resumed starting from March 2003 and fully recovered by the end of July. Periodic sampling of the lava at the active vents was carried out during the entire effusive event. All the analysed samples are shoshonitic basalts (SiO2 48.5–50.4 wt.%; K2O 2.1–2.4 wt.%) in the range of composition observed in the products erupted during the past 20 years. They bear about 50 vol.% zoned crystals of plagioclase An90–60, diopside–augite and olivine Fo70–73 in a compositionally homogeneous shoshonitic groundmass. Bulk rock major and trace element contents measured with different methodologies at different laboratories show only minor variations. Sr and Nd isotope ratios are close to those of the crystal-rich scoriae erupted in the previous years. Despite of small compositional variations related to the emptying of the zoned topmost portion of the conduit, the data show that the switch from Strombolian explosive to effusive activity is not associated with changes of the textures and composition of the erupted products. Slight but somehow systematic variation of trace elements and isotope ratios between products erupted before and after the 5 April eruption are likely accounted by limited mixing between the fresh, volatile-rich, crystal-poor, magma erupted as pumice during the paroxysm, and the volatile-poor, crystal-rich magma feeding the lava flow. The uniform composition of the erupted lava indicates the presence of a large volume of well-mixed, crystal-rich, homogeneous magma residing in the shallow plumbing system of the volcano. Two possible trigger mechanism of the effusive event are here proposed: (i) a discrete input of fresh magma into the lower part of the shallow magmatic system occurred some months before the eruption and was followed by crystallisation, degassing and mixing with the crystal-rich shallow magma which re-homogenised the system. These processes eventually led to the rise of the magma at a higher level and failure of the conduit walls. (ii) The onset of the effusion may represent the consequence of a gradual rise of the magma level in the conduits occurred in the past two decades. The process of progressive refilling, initiated after the 1985 effusive eruption, ultimately culminated on 28 December 2002 with the failure of the conduit wall and the opening of vents 100–150 m below the summit craters
    Description: Published
    Description: 263-284
    Description: JCR Journal
    Description: reserved
    Keywords: Stromboli volcano ; Aeolian Islands ; 2002–2003 eruption ; Mineralogy ; Geochemistry ; Sr isotope ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
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  • 46
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    Textural effects of steady state behaviour of the Stromboli feeding system (2007)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The exceptionally persistent activity of Stromboli volcano has lasted for at least 1400 years. The normal strombolian activity is periodically interrupted by more energetic explosions (1–2 per year) and by sporadic effusive episodes (every 10–20 years). Normal activity and effusive episodes are characterized by crystal-rich high-K to shoshonitic basalts issuing from a volatile-poor shallow system. Crystal-poor pumice are emitted only during more violent explosions, and are thought to derive from deep pulses of volatile-rich magma. Shallow level degassing induces massive crystallization of deep pulses of feeding magma that, continuously mixing with the resident one, produces the crystal-rich shoshonite of the persistent activity. We examined the crystallization history of the crystal-rich, shallow reservoir using plagioclase Crystal Size Distribution (CSD) analysis of scoriae and lavas emitted in the past twenty years. CSDs show a linear dependence from crystal size in the size interval 0.06–1.2 mm; number density of larger crystals is biased by right hand truncation effects. CSDs slopes and intercepts are quite constant during the whole considered time span revealing a system that is close to the equilibrium also from a kinetic point of view. The linear crystal size distribution are reached by the system through episodes of growth and resorption, respectively occurring in the degassed and undegassed magma during the continuous mixing in the feeding system. Plagioclase net growth rate (2 × 10− 11 cm/s) results from a balance of growth (10− 10 cm/s) and resorption episodes which induce spectacular zoning and resorption textures in crystals larger than 200 μm. CSDs of mafic phases cannot be accurately acquired on each single sample due to poor counting statistics; the evaluation of pyroxene and olivine CSD on the whole data set, however, confirms the conclusions acquired from plagioclase CSDs.
    Description: Published
    Description: 86-98
    Description: 2.4. TTC - Laboratori di geochimica dei fluidi
    Description: JCR Journal
    Description: reserved
    Keywords: crystal size distribution ; plagioclase growth ; magma residence time ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
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  • 47
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    A parallel multiphase flow code for the 3D simulation of explosive volcanic eruptions (2007)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: A new parallel code for the simulation of the transient, 3D dispersal of volcanic particles in the atmosphere is presented. The model equations, describing the multiphase flow dynamics of gas and solid pyroclasts ejected from the volcanic vent during explosive eruptions, are solved by a finite-volume discretization scheme and a pressure-based iterative non-linear solver suited to compressible multiphase flows. The solution of the multiphase equation set is computationally so demanding that the simulation of the transient 3D dynamics of eruptive columns would not be cost-effective on a single workstation. The new code has been parallelized by adopting an ad hoc domain partitioning scheme that enforces the load balancing in the presence of a large number of topographic blocking-cells. An optimized communication layer has been built over the Message-Passing Interface. It is shown that the present code has a remarkable efficiency on several high-performance platforms and makes it possible, for the first time, to simulate fully 3D eruptive scenarios on realistic volcano topography.
    Description: Published
    Description: 541-560
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: Message passing interface ; Computational fluid dynamics ; Multiphase flow ; Explosive eruption ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 48
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    Modelling of the 2001 Lava Flow at Etna Volcano by a Cellular Automata Approach (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The 2D Cellular Automata model, MAGFLOW, simulates lava flows and an algorithm based on the Monte Carlo approach solves the anisotropic flow direction problem. The model was applied to reproduce a lava flow formed during the 2001 Etna eruption. This eruption provided the opportunity to verify the ability of MAGFLOW to simulate the path of lava flows. made possible due to the availability of the necessary data for both modeling and subsequent validation. MAGFLOW reproduced quite accurately the spread of flow. A good agreement was highlighted between the simulated and observed length on steep slopes, whereas the area covered by the lava flow tends to be overestimated. The major inconsistencies found in the comparison between simulated and observed lava flow due to neglecting the effects of ephemeral vent formation.
    Description: Published
    Description: 1465-1471
    Description: 3.6. Fisica del vulcanismo
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: reserved
    Keywords: Lava Flow Simulation ; Etna Volcano ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.01. Computational geophysics::05.01.02. Cellular automata, fuzzy logic, genetic alghoritms, neural networks
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  • 49
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    Paleo-environmental and volcano-tectonic evolution of the southeastern £ank of Mt. Etna during the last 225 ka inferred from the volcanic succession of the ‘Timpe’, Acireale, Sicily (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The tectonic escarpments locally known as ‘Timpe’ cut a large sector of the eastern flank of Etna, and allow an ancient volcanic succession dating back to 225 ka to be exposed. Geological and volcanological investigations carried out on this succession have allowed us to recognize relevant angular unconformities and volcanic features which are the remnants of eruptive fissures, as well as important changes in the nature, composition and magmatic affinity of the exposed volcanics. In particular, the recognition in the lower part of the succession of important and unequivocal evidence of ancient eruptive fissures led us to propose a local origin for these volcanics and to revise previous interpretations which attributed their westward-dipping to the progressive tectonic tilting of strata. These elements led us to reinterpret the main features of the volcanic activity occurring since 250 ka BP and their relationship with tectonic structures active in the eastern flank of Etna. We propose a complex paleo-environmental and volcanotectonic evolution of the southeastern flank of Mt. Etna, in which the Timpe fault system played the role of the crustal structure that allowed the rise and eruption of magmas in the above considered time span.
    Description: Published
    Description: 289-306
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.5. Geologia e storia dei sistemi vulcanici
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: Mount Etna ; tectonics ; fisssure eruptions ; columnar basalt ; fault escarpment ; xenoliths ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.03. Geomorphology ; 04. Solid Earth::04.04. Geology::04.04.05. Mineralogy and petrology ; 04. Solid Earth::04.04. Geology::04.04.06. Rheology, friction, and structure of fault zones ; 04. Solid Earth::04.04. Geology::04.04.07. Rock geochemistry ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.04. Geology::04.04.10. Stratigraphy ; 04. Solid Earth::04.04. Geology::04.04.11. Instruments and techniques ; 04. Solid Earth::04.07. Tectonophysics::04.07.99. General or miscellaneous ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.04. Plate boundaries, motion, and tectonics ; 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
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  • 50
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    An automatic procedure to forecast tephra fallout (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Tephra fallout constitutes a serious threat to communities around active volcanoes. Reliable short-term 13 forecasts represent a valuable aid for scientists and civil authorities to mitigate the effects of fallout on the 14 surrounding areas during an episode of crisis. We present a platform-independent automatic procedure with Q1 15 the aim to daily forecast transport and deposition of volcanic particles. The procedure builds on a series of 16 programs and interfaces that automate the data flow and the execution and subsequent postprocess of fallout 17 models. Firstly, the procedure downloads regional meteorological forecasts for the area and time interval of 18 interest, filters and converts data from its native format, and runs the CALMET diagnostic model to obtain the 19 wind field and other micro-meteorological variables on a finer local-scale 3-D grid defined by the user. 20 Secondly, it assesses the distribution of mass along the eruptive column, commonly by means of the radial 21 averaged buoyant plume equations depending on the prognostic wind field and on the conditions at the vent 22 (granulometry, mass flow rate, etc). All these data serve as input for the fallout models. The initial version of 23 the procedure includes only two Eulerian models, HAZMAP and FALL3D, the latter available as serial and 24 parallel implementations. However, the procedure is designed to incorporate easily other models in a near 25 future with minor modifications on the model source code. The last step is to postprocess the outcomes of 26 models to obtain maps written in standard file formats. These maps contain plots of relevant quantities such 27 as predicted ground load, expected deposit thickness and, for the case of or 3-D models, concentration on air 28 or flight safety concentration thresholds
    Description: Published
    Description: 767-777
    Description: 3.6. Fisica del vulcanismo
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: reserved
    Keywords: Tephra fallout ; volcanoes ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.09. Miscellaneous::05.09.99. General or miscellaneous
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  • 51
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    The 2007 eruption of Stromboli volcano: Insights from real-time measurement of the volcanic gas plume CO2/SO2 ratio (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The recent eruption of Stromboli in February–April 2007 offered a unique chance to test our current understanding of processes driving the transition from ordinary (persistent Strombolian) to effusive activity, and the ability of instrumental geophysical and geochemical networks to interpret and predict these events. Here, we report on the results of two years of in-situ sensing of the CO2/SO2 ratio in Stromboli's volcanic gas plume, in the attempt to put constraints on the trigger mechanisms and dynamics of the eruption. We show that large variations of the plume CO2/SO2 ratio (range, 0.9–26) preceded the onset of the eruption (since December 2007), interrupting a period of relatively-steady and low ratios (time-averaged ratio, 4.3) lasting from at least May to November 2006. By contrasting our observations with numerical simulations of volcanic degassing at Stromboli, derived by use of an equilibrium saturation model, we suggest that the pre-eruptive increase of the ratio reflected an enhanced supply of deeply-derived CO2-rich gas bubbles to the shallowplumbing system. This larger-than-normal ascent of gas bubbles was likely sourced by a 1–3 km deep gas– melt separation region (probably a magma storage zone), and caused faster convective overturning of magmas in the shallow conduit; an increase in the explosive rate and in seismic tremor, and finally the collapse of the la Sciara del Fuoco sector triggering the effusive phase. The high CO2/SO2 ratios (up to 21) observed during the effusive phase, and particularly in the days and hours before a paroxysmal explosion on March 15, 2007, indicate the persistence of the same gas source; and suggest that de-pressurization of the same 1–3 km deep magma storage zone could have been the trigger mechanism for the paroxysm itself
    Description: In press
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: 2.4. TTC - Laboratori di geochimica dei fluidi
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: Stromboli ; plume chemistry ; magma degassing ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.04. Thermodynamics ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 52
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    Explosive activity and eruption scenarios at Somma-Vesuvius (Italy): Towards a new classification scheme (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: A new proposal for the classification of Somma-Vesuvius (SV) explosive activity is presented, based on a critical revision of a large set of published and unpublished stratigraphic, compositional, and physical volcanology data on the products of the past 20,000 years of activity. The new database is used to discuss the general behaviour of the volcano in terms of frequency, magnitude and intensity of the events, as well as of the length of the repose time which preceded each eruption. Several different types of eruption are recognized, each characterised by specific physical eruptive parameters: plinian, subplinian (further subdivided in subplinian I and subplinian II), violent strombolian, ash emission events. For each eruption type, a complex scenario is described, with phases of different style, duration, magnitude and intensity occurring during the course of the eruption itself. The name given to each eruption type is derived from the style of the most representative part of the eruption (in terms of duration or volume). On the whole, the magnitude (expressed as the volume of erupted magma) of the past SV eruptions has been roughly decreasing with time while, starting from 3900 years BP, their frequency has been increasing. The eruption intensity, expressed as the estimated magma discharge rate (MDR) continuously increases with increasing magnitude from strombolian to plinian eruptions, the most voluminous plinian events being, however, characterised by a lower MDR than the smaller ones. The length of the “apparent” repose preceding an eruption (the difference in age between one deposit and that immediately on top of it) appears clearly correlated with magnitude for the most intense eruptions (plinian and subplinian I), while this correlation is poorer for eruptions of intermediate size (from violent strombolian to subplinian II). These exhibit a large variability in magnitude, intensity and eruption style for a range of repose time varying from dozens to hundreds of years, then including the current duration of Vesuvius quiescence. By reckoning with the whole range of possibilities that a next unrest at Vesuvius implies, the set of presented eruption scenarios can be useful both for developing a probabilistic approach to hazard assessment and depicting a range of impact scenarios. The scenario for high-intensity events had been already well defined since 1995, in order to redact the emergency plan of the National Department of Civil Defence. Conversely, it is now clear that the impact on the territory of long-lasting, although low-intensity, eruptions (subplinian II, violent strombolian, ash emission activity) can be relevant especially in terms of economic costs. A larger consideration of this type of activity at Vesuvius can be important especially for the aspects of emergency planning and risk reduction.
    Description: Published
    Description: 331-346
    Description: 3.5. Geologia e storia dei sistemi vulcanici
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: reserved
    Keywords: Explosive eruption ; Eruption scenario ; Volcanic history ; Somma-Vesuvius ; Volcanic hazard ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 53
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    Volcanic risk perception in the Vesuvius population (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: A volcanic risk perception study of the population residing near Vesuvius was carried out between May and July, 2006. A total of 3600 questionnaires with 45 items were distributed to students, their parents and the general population. The largest number of surveys (2812) were distributed in the 18 towns of the Red Zone, the area nearest to the volcano that is exposed to pyroclastic flow hazards and whose 550,000 residents, according to the civil protection emergency plan (in operation since 1995), should be evacuated in case of an eruption crisis. The remaining 788 questionnaires were distributed in 3 additional towns and 3 neighborhoods of Naples, all within the Yellow Zone, which is an area exposed to pyroclastic fallout hazards. A total of 2655 surveys were returned, resulting in a response rate of 73.7%. Results indicated that people have a realistic view of the risk: they think that an eruption is likely, that it will have serious consequences for their towns and for themselves and their families and they are quite worried about the threat. However, several other social, economic, and security-related issues were listed as a problem more often than Vesuvius. The study also demonstrated a widespread lack of knowledge about the emergency plan, a lack of confidence in the plan's success and in public officials and low feelings of self-efficacy. People want to be more deeply involved in public discussions with scientists and civil protection officials on emergency planning and individual preparedness measures. It is clear from the results that a major education-information effort is still needed to improve the public's knowledge, confidence and self-efficacy, thereby improving their collective and individual capability to positively face a future volcanic emergency.
    Description: Published
    Description: 244–258
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: reserved
    Keywords: volcanic risk perception ; Vesuvius ; confidence on emergency plan and public officials ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 54
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    Developing an Event Tree for probabilistic hazard and risk assessment at Vesuvius (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Probabilistic characterizations of possible future eruptive scenarios at Vesuvius volcano are elaborated and organized within a risk-based framework. In the EXPLORIS project, a wide variety of topics relating to this basic problem have been pursued: updates of historical data, reinterpretation of previous geological field data and the collection of new fieldwork results, the development of novel numerical modelling codes and of risk assessment techniques have all been completed. To achieve coherence, many diverse strands of evidence had to be unified within a formalised structure, and linked together by expert knowledge. For this purpose, a Vesuvius ‘Event Tree’ (ET) was created to summarise in a numerical-graphical form, at different levels of detail, all the relative likelihoods relating to the genesis and style of eruption, development and nature of volcanic hazards, and the probabilities of occurrence of different volcanic risks in the next eruption crisis. The Event Tree formulation provides a logical pathway connecting generic probabilistic hazard assessment to quantitative risk evaluation. In order to achieve a complete parameterization for this all-inclusive approach, exhaustive hazard and risk models were needed, quantified with comprehensive uncertainty distributions for all factors involved, rather than simple ‘best-estimate’ or nominal values. Thus, a structured expert elicitation procedure was implemented to complement more traditional data analysis and interpretative approaches. The structure of the Vesuvius Event Tree is presented, and some of the data analysis findings and elicitation outcomes that have provided initial indicative probability distributions to be associated with each of its branches are summarized. The Event Tree extends from initiating volcanic eruption events and hazards right through to human impact and infrastructure consequences, with the complete tree and its parameterisation forming a quantitative synoptic framework for comprehensive hazard evaluation and mapping of risk impacts. The organization of the Event Tree allows easy updating, as and when new information becomes available
    Description: Published
    Description: 397-415
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: reserved
    Keywords: Vesuvius ; volcanic hazard ; volcanic risk ; probabilistic risk assessment ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 55
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    Hazards from pyroclastic density currents at Mt. Etna (Italy) (2008)
    Elsevier
    Details
    Publication Date: 2017-04-03
    Description: Despite the recent recognition of Mount Etna as a periodically violently explosive volcano, the hazards from various types of pyroclastic density currents (PDCs) have until now received virtually no attention at this volcano. Large-scale pyroclastic flows last occurred during the caldera-forming Ellittico eruptions, 15–16 ka ago, and the risk of them occurring in the near future is negligible. However, minor PDCs can affect much of the summit area and portions of the upper flanks of the volcano. During the past ~ 20 years, small pyroclastic flows or base-surge-like vapor and ash clouds have occurred in at least 8 cases during summit eruptions of Etna. Four different mechanisms of PDC generation have been identified during these events: (1) collapse of pyroclastic fountains (as in 2000 and possibly in 1986); (2) phreatomagmatic explosions resulting from mixing of lava with wet rock (2006); (3) phreatomagmatic explosions resulting from mixing of lava with thick snow (2007); (4) disintegration of the unstable flanks of a lava dome-like structure growing over the rim of one of the summit craters (1999). All of these recent PDCs were of a rather minor extent (maximum runout lengths were about 1.5 km in November 2006 and March 2007) and thus they represented no threat for populated areas and human property around the volcano. Yet, events of this type pose a significant threat to the lives of people visiting the summit area of Etna, and areas in a radius of 2 km from the summit craters should be off-limits anytime an event capable of producing similar PDCs occurs. The most likely source of further PDCs in the near future is the Southeast Crater, the youngest, most active and most unstable of the four summit craters of Etna, where 6 of the 8 documented recent PDCs originated. It is likely that similar hazards exist in a number of volcanic settings elsewhere, especially at snow- or glacier-covered volcanoes and on volcano slopes strongly affected by hydrothermal alteration.
    Description: In press
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: reserved
    Keywords: Mt. Etna ; Pyroclastic density currents ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 56
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    FALL3D: A Computational Model for Trans-port and Deposition of Volcanic Ash (2008)
    Elsevier
    Details
    Publication Date: 2020-03-19
    Description: FALL3D is a 3-D time-dependent Eulerian model for the transport and deposition of 8 volcanic ash. The model solves the advection-diffusion-sedimentation (ADS) equa- 9 tion on a structured terrain-following grid using a second-order Finite Differences 10 (FD) explicit scheme. Different parameterizations for the eddy diffusivity tensor 11 and for the particle terminal settling velocities can be used. The code, written 12 in FORTRAN 90, is available in both serial and parallel versions for Windows and 13 Unix/Linux/Mac X Operating Systems (OS). A series of pre- and post-process util- 14 ity programs and OS-dependent scripts to launch them are also included in the 15 FALL3D distribution package. Although the model has been designed to forecast 16 volcanic ash concentration in the atmosphere and ash loading at ground, it can also 17 be used to model the transport of any kind of airborne solid particles. The model 18 inputs are meteorological data, topography, grain-size distribution, shape and den- 19 sity of particles, and mass rate of particle injected into the atmosphere. Optionally, 20 FALL3D can be coupled with the output of the meteorological processor CALMET, a 21 diagnostic model which generates 3-D time-dependent zero-divergence wind fields 22 from mesoscale forecasts incorporating local terrain effects. The FALL3D model can 23 be a tool for short-term ash deposition forecasting and for volcanic fallout hazard 24 assessment. As an example, an application to the 22 July 1998 Etna eruption is also 25 presented.
    Description: Published
    Description: 1334–1342
    Description: 3.6. Fisica del vulcanismo
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: open
    Keywords: volcanic ash ; fallout ; computational model ; FORTRAN code ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.01. Computational geophysics::05.01.99. General or miscellaneous
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  • 57
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    The Campanian Ignimbrite and Codola tephra layers: Two temporal/stratigraphic markers for the Early Upper Palaeolithic in southern Italy and eastern Europe (2008)
    Elsevier
    Details
    Publication Date: 2020-02-24
    Description: Tephra layers from archaeological sites in southern Italy and eastern Europe stratigraphically associated with cultural levels containing Early Upper Palaeolithic industry were analysed. The results confirm the occurrence of the Campanian Ignimbrite tephra (CI; ca. 40 cal ka BP) at Castelcivita Cave (southern Italy), Temnata Cave (Bulgaria) and in the Kostenki–Borshchevo area of the Russian Plain. This tephra, originated from the largest eruption of the Phlegrean Field caldera, represents the widest volcanic deposit and one of the most important temporal/stratigraphic markers of western Eurasia. At Paglicci Cave and lesser sites in the Apulia region we recognise a chemically and texturally different tephra, which lithologically, chronologically and chemically matches the physical and chemical characteristics of the Plinian eruption of Codola; a poorly known Late Pleistocene explosive event from the Neapolitan volcanoes, likely Somma–Vesuvius. For this latter, we propose a preliminary age estimate of ca. 33 cal ka BP and a correlation to the widespread C-10 marine tephra of the central Mediterranean. The stratigraphic position of both CI and Codola tephra layers at Castelcivita and Paglicci help date the first and the last documented appearance of Early Upper Palaeolithic industries of southern Italy to ca. 41–40 and 33 cal ka BP, respectively, or between two interstadial oscillations of the Monticchio pollen record – to which the CI and Codola tephras are physically correlated – corresponding to the Greenland interstadials 10–9 and 5. In eastern Europe, the stratigraphic and chronometric data seem to indicate an earlier appearance of the Early Upper Palaeolithic industries, which would predate of two millennia at least the overlying CI tephra. The tephrostratigraphic correlation indicates that in both regions the innovations connected with the so-called Early Upper Palaeolithic – encompassing subsistence strategy and stone tool technology – appeared and evolved during one of the most unstable climatic phases of the Last Glacial period. On this basis, the marked environmental unpredictability characterising this time-span is seen as a potential ecological factor involved in the cultural changes observed.
    Description: Published
    Description: 208–226
    Description: 3.5. Geologia e storia dei sistemi vulcanici
    Description: 3.6. Fisica del vulcanismo
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: reserved
    Keywords: Campanian Ignimbrite ; Early Upper Palaeolithic ; Codola Plinian eruption ; south-eastern Europe ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
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  • 58
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    Transient 3D numerical simulations of column collapse and pyroclastic density current scenarios at Vesuvius (2008)
    Elsevier
    Details
    Publication Date: 2021-09-20
    Description: Numerical simulations of column collapse and pyroclastic density current (PDC) scenarios at Vesuvius were carried out using a transient 3D flow model based on multiphase transport laws. The model describes the complex dynamics of the collapse as well as the effects of the 3D topography of the volcano on PDC propagation. Source conditions refer to a medium-scale sub-Plinian event and consider a pressure-balanced jet. Simulation results provide new insights into the complex dynamics of these phenomena. In particular: 1) column collapse can be characterized by different regimes, from incipient collapse to partial or nearly total collapse, thus confirming the possibility of a transitional field of behaviour of the column characterized by the contemporaneous and/or intermittent occurrence of ash fallout and PDCs; 2) the collapse regime can be characterized by its fraction of eruptive mass reaching the ground and generating PDCs; 3) within the range of the investigated source conditions, the propagation and hazard potential of PDCs appear to be directly correlated with the flow-rate of the mass collapsing to the ground, rather than to the collapse height of the column (this finding is in contrast with predictions based on the energy-line concept, which simply correlates the PDC runout and kinetic energy with the collapse height of the column); 4) first-order values of hazard variables associated with PDCs (i.e., dynamic pressure, temperature, airborne ash concentration) can be derived from simulation results, thereby providing initial estimates for the quantification of damage scenarios; 5) for scenarios assuming a location of the central vent coinciding with that of the present Gran Cono, Mount Somma significantly influences the propagation of PDCs, largely reducing their propagation in the northern sector, and diverting mass toward the west and southeast, accentuating runouts and hazard variables for these sectors; 6) the 2D modelling approximation can force an artificial radial propagation of the PDCs since it ignores azimuthal flows produced by real topographies that therefore need to be simulated in fully 3D conditions.
    Description: Published
    Description: 378-396
    Description: 3.6. Fisica del vulcanismo
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: reserved
    Keywords: Vesuvius ; pyroclastic density current ; column collapse ; numerical simulation ; 3D modelling ; hazard assessment ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 59
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    A case history of paroxysmal explosion at Stromboli: Timing and dynamics of the April 5, 2003 event (2007)
    Elsevier
    Details
    Publication Date: 2023-01-16
    Description: On April 5, 2003, Stromboli volcano (Italy) produced the most violent explosion of the past 50 years. The event was exceptionally well documented thanks to the presence on the island of several scientists and a large number of instruments deployed over the preceding months to monitor the effusive eruption that began in December 2002. Integration of visual documentation, deposit features and geophysical data allowed an accurate reconstruction of the explosive event and its dynamics. The eruption consisted of a 8-min long explosive event which evolved through four phases whose timing was precisely recorded by an infrared thermometer located about 450 m from the summit crater. Phases 2 and 3 lasted 39 and 42 s, respectively. Both had an impulsive character, were responsible for ejecting almost the entire mass of the pyroclastic products. Phases 1 and 4 represented, respectively, a short-lived precursory event and a waning tale. During Phase 2, meter-sized ballistic blocks were launched with velocities of 170 m/s to altitudes of up to 1400 m above the craters. These fell on the volcano flanks and on the village of Ginostra, about 2 km distant from the vent. A vertical jet rose above the craters which developed to feed a convective plume that reached a height of up to 4 km. The calculated mass of the Phase 2 fallout deposit and mass discharge rate were 1.1–1.4×108 kg and 2.8– 3.6×106 kg/s, respectively. During Phase 3 a scoria flow deposit, with an estimated volume of 0.9–1.1×104 m3, was erupted from the same vent that fed the ongoing sustained lava flow. The average mass discharge rate for this phase was 2.5–3.1×105 kg/s. Products emitted during Phases 2 and 3 consisted of lithic and fresh magmatic material in similar proportions. The juvenile fraction consisted of a deep-originated, almost aphyric, highly vesicular pumice mingled with a shallow-derived, crystal-rich, moderately vesicular scoria. Similarities with the eruption dynamics of other historical paroxysms at Stromboli makes the April 5, 2003 explosion representative of these highly energetic events that constitute the most hazardous volcanic phenomena at Stromboli volcano.
    Description: Published
    Description: 594-606
    Description: JCR Journal
    Description: reserved
    Keywords: stromboli ; Thermal monitoring; paroxysm ; explosive dynamics ; ballistic ejecta ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
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