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  • Elsevier  (90,657)
  • Essen : Verl. Glückauf
  • Krefeld : Geologischer Dienst Nordhein-Westfalen
  • 2005-2009  (90,658)
  • 2005  (90,658)
Collection
Keywords
Publisher
Language
Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    A measurement of τ polarization in Z^0 decays (1992-8977)
    Amsterdam : Elsevier
    Physics Letters B 294 (1992), S. 466-478 
    Details
    ISSN: 0370-2693
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0370-2693(92)91549-O
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    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Measurement of the average lifetime of b hadrons (1993-4325)
    Amsterdam : Elsevier
    Physics Letters B 317 (1993), S. 474-484 
    Details
    ISSN: 0370-2693
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0370-2693(93)91027-K
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  • 3
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    Helium–strontium isotope constraints on mantle evolution beneath the Roman Comagmatic Province, Italy (2005)
    Elsevier
    Details
    Publication Date: 2020-12-03
    Description: A study of the He isotopic ratios of fluid inclusions in olivine and pyroxene from the Roman Comagmatic Province (RCP),Italy, is presented together with 87Sr/86Sr isotope compositions of the whole rock or pyroxene phenocrysts. A clear covariation in He and Sr isotopes is apparent, with a strong northward increase in radiogenic He and Sr being evident. He and Sr isotopes ratios range from 3He/4He = 5.2 Ra and 87Sr/86Sr = 0.7056 in south Campania, to 3He/4He = 0.44 Ra and 87Sr/86Sr = 0.715905 in the northernmost Latium. Helium isotope ratios are significantly lower than MORB values and are among the lowest yet measured in subduction zone volcanism. The 3He/4He of olivine and pyroxene phenocryst-hosted volatiles appear to be little influenced by posteruptive processes and magma–crust interaction. The 3He/4He–87Sr/86Sr covariation is consistent with binary mixing between an asthenospheric mantle similar to HIMU ocean island basalts, and an enriched (radiogenic) mantle end member generated from subduction of the Ionian/Adriatic plate. The contribution of radiogenic He from metasomatic fluids and postmetasomatism radiogenic ingrowth in the wedge is strongly dependent on the initial He concentration of the mantle. Only when asthenosphere He concentrations are substantially lower than the MORB source mantle, and metasomatism occurred at the beginning of the subduction (f30 Ma), can ingrowth in the mantle wedge account for the 3He/4He of the most radiogenic basalts.
    Description: - European Social Fund - Scottish Universities - Carnegie Trust for the Universities of Scotland.
    Description: Published
    Description: 295–308
    Description: partially_open
    Keywords: Roman Comagmatic Province ; fluid inclusions ; helium ; strontium ; 04. Solid Earth::04.01. Earth Interior::04.01.03. Mantle and Core dynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.06. Subduction related processes ; 04. Solid Earth::04.07. Tectonophysics::04.07.08. Volcanic arcs ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 4
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    Tectonic control on the eruptive dynamics at Mt. Etna Volcano (Sicily) during the 2001 and 2002–2003 eruptions (2005)
    Elsevier
    Details
    Publication Date: 2020-12-15
    Description: The eruptive events of the July–August 2001 and October 2002–January 2003 at Mt. Etna provide new insights for reconstructing the complex geometry of the feeding system and their relationship to regional tectonics. The 2001 eruption took place mainly on the upper southern sector of the volcano. The eruption was preceded by a large earthquake swarm for a few days before its onset and accompanied by ground deformation and fracturing. The development of surface cracking along with the seismic pattern has allowed us to recognize three distinct eruptive systems (the SW–NE, NNW–SSE and N–S systems) which have been simultaneously active. Such eruptive systems are only the upper portions of a complex feeding system that was fed at the same time by two distinct magmas. The SW–NE and NNW–SSE systems, connected with the SE crater conduit, were fed by magma coming from depth, whereas the N–S system served instead as an ascending pathway for an amphibole-bearing magma residing in a shallow reservoir. The eruptive activity started again on October 2002 on the NE Rift Zone, where about 20 eruptive vents were aligned between 2500 and 1900 m a.s.l., and on the southern flank, from the central crater to the Montagnola. The onset of eruptive activity was accompanied by a seismic swarm. As in the 2001 eruptive event, two independent feeding systems formed, characterized by distinct magmas. The SW–NE system controlled the feeding of the Northeast Rift and was accommodated by left-lateral displacement along the WNW–ESE trending Pernicana Fault. The N–S system fed the eruptions on the southern flank. Moreover, the associated crustal deformation triggered seismic reactivation of tectonic structures in the eastern flank of the volcano and offshore. These two last eruptions indicate that at Mt. Etna the ascent of magma, as well as the accommodation of deformation, is strongly dominated by local extensional structures that are connected to a regional tectonic regime.
    Description: Published
    Description: 211-233
    Description: partially_open
    Keywords: extensional tectonics ; volcanic activity ; seismicity ; Sicily ; Mt. Etna ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 5
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    Reverse migration of seismicity on thrusts and normal faults (2005)
    Elsevier
    Details
    Publication Date: 2021-01-27
    Description: In this work, the control exerted by the stress axes orientation on the evolution of seismic sequences developing in compressive and extensional regimes is analysed. According to the Anderson fault theory, the vertical stress is the minimum principal stress in compressional tectonic regimes, whereas it is the maximum principal stress in extensional regimes. Using Mohr diagrams and discussing the present knowledge about the distribution of vertical and horizontal stress with depth we show that, in absence of localised fluid overpressure, such changes imply that thrust and normal faults become more unstable at shallower and greater depths, respectively. These opposite mechanical behaviours predict, in a rather isotropic body, easier rupture at shallower level in compressional regimes later propagating downward. On the contrary, a first deep rupture propagating upward is expected in extensional regimes. This is consistent with observations from major earthquakes from different areas in the world. We show that the exceptions to downward migration along thrusts occur along steeply inclined faults and probably imply localised supra-hydrostatic fluid pressures. Moreover, we show that the inversion of the meaning of the lithostatic load has consequences also for the role of topography. High topography, increasing the vertical load, should inhibit earthquake development in compressional environments and should favour it in extensional settings. Although several factors, such as geodynamic processes, local tectonic features and rock rheology, are likely to control earthquake locations, stress distribution and tectonic regime, these model predictions are consistent with seismicity distribution in Italy, central Andes and Himalaya. In these areas, large to medium compressional earthquakes occur at the low elevation borders of compressional mountain belts, whereas large extensional earthquakes occur in correspondence to maximum elevations.
    Description: ASI 2001, Cofin 2001 and GNDT fundings
    Description: Published
    Description: 195-222
    Description: partially_open
    Keywords: Seismicity migration ; thrusts ; normal faults ; aftershocks ; 04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article , article
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  • 6
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    Dynamics of magma ascent and fragmentation in trachytic versus rhyolitic eruptions (2005)
    Elsevier
    Details
    Publication Date: 2020-10-29
    Description: We have performed a parametric study on the dynamics of trachytic (alkaline) versus rhyolitic (calc-alkaline) eruptions by employing a steady, isothermal, multiphase non-equilibrium model of conduit flow and fragmentation. The employed compositions correspond to a typical rhyolite and to trachytic liquids from Phlegrean Fields eruptions, for which detailed viscosity measurements have been performed. The investigated conditions include conduit diameters in the range 30–90 m and total water contents from 2 to 6 wt%, corresponding to mass flow rates in the range 106–108 kg/s. The numerical results show that rhyolites fragment deep in the conduit and at a gas volume fraction ranging from 0.64 to 0.76, while for trachytes fragmentation is found to occur at much shallower levels and higher vesicularities (0.81–0.85). An unexpected result is that low-viscosity trachytes can be associated with lower mass flow rates with respect to more viscous rhyolites. This is due to the non-linear combined effects of viscosity and water solubility affecting the whole eruption dynamics. The lower viscosity of trachytes, together with higher water solubility, results in delayed fragmentation, or in a longer bubbly flow region within the conduit where viscous forces are dominant. Therefore, the total dissipation due to viscous forces can be higher for the less viscous trachytic magma, depending on the specific conditions and trachytic composition employed. The fragmentation conditions determined through the simulations agree with measured vesicularities in natural pumice clasts of both magma compositions. In fact, vesicularities average 0.80 in pumice from alkaline eruptions at Phlegrean Fields, while they tend to be lower in most calc-alkaline pumices. The results of numerical simulations suggest that higher vesicularities in alkaline products are related to delayed fragmentation of magmas with this composition. Despite large differences in the distribution of flow variables which occur in the deep conduit region and at fragmentation, the flow dynamics of rhyolites and trachytes in the upper conduit and at the vent can be very similar, at equal conduit size and total water content. This is consistent with similar phenomenologies of eruptions associated with the two magma types.
    Description: Published
    Description: 93-108
    Description: partially_open
    Keywords: trachytic magma ; conduit flow ; eruption dynamics and numerical simulations ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 7
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    The age of the Neapolitan Yellow Tu caldera-forming eruption (Campi Flegrei caldera-Italy) assessed by 40Ar/39Ar dating method (2005)
    Elsevier
    Details
    Publication Date: 2020-12-17
    Description: The Neapolitan Yellow Tuff (NYT) is the product of the largest known trachytic phreatoplinian eruption. It covered an area larger than 1000 km2 with an estimated volume of about 40 km3 of erupted magma. During the course of the eruption a caldera collapsed within the previously formed Campanian Ignimbrite caldera. The resulting nested structure strongly influenced the following volcanic activity in the Campi Flegrei caldera. As previous dating of the NYT does not converge toward a unique result, a new set of 40Ar/39Ar age determinations has been carried out to better constrain the age of the eruption. Two variants of the 40Ar/39Ar dating method were applied to determine the age of the NYT eruption: (1) single-crystal total fusion (SCTF), on an individual phenocryst of feldspar, and (2) laser incremental heating (LIH), on bulk aliquots of feldspar phenocrysts. The results of the SCTF analyses show that the overall sample weighted mean age, derived from the conventional age calculation, is 15.6 ;0.8 ka. A weighted mean of the isochron age is 15.3 ;1.2 ka (2c), and has been assumed as the best indicator of age to be derived from the SCTF analyses. The LIH analyses results show that plateau ages vary from 15.4; 0.5 to 14.5; 0.5 ka. The overall weighted mean age of the isochron results is 14.9;0.4 ka (2c). This result has been assumed as the reference age for the NYT eruption, and agrees with the SCTF age. The new age obtained for the NYT deposits is of great relevance for the understanding of the evolution and the present state of the Campi Flegrei caldera and collocates the NYT in a crucial stratigraphical position to date the climatic oscillations that occurred between the Late Glacial and the Holocene.
    Description: Published
    Description: 157-170
    Description: partially_open
    Keywords: Neapolitan Yellow Tuff ; Campi Flegrei caldera ; 40Ar/39Ar dating method ; Geochronology ; Late Glacial ; Holocene ; 04. Solid Earth::04.04. Geology::04.04.02. Geochronology ; 04. Solid Earth::04.04. Geology::04.04.10. Stratigraphy ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 8
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    Magma-derived gas influx and water-rock interactions in the volcanic aquifer of Mt. Vesuvius, Italy (2005)
    Elsevier
    Details
    Publication Date: 2021-06-25
    Description: We report in this paper a systematic investigation of the chemical and isotopic composition of groundwaters flowing in the volcanic aquifer of Mt. Vesuvius during its current phase of dormancy, including the first data on dissolved helium isotope composition and tritium content. The relevant results on dissolved He and C presented in this paper reveal that an extensive interaction between rising magmatic volatiles and groundwaters currently takes place at Vesuvius. Vesuvius groundwaters are dilute (mean TDS 2800 mg/L) hypothermal fluids (mean T 17.7°C) with a prevalent alkaline-bicarbonate composition. Calcium-bicarbonate groundwaters normally occur on the surrounding Campanian Plain, likely recharged from the Apennines. D and 18O data evidence an essentially meteoric origin of Vesuvius groundwaters, the contribution from either Tyrrhenian seawater or 18O-enriched thermal water appearing to be small or negligible. However, the dissolution of CO2-rich gases at depth promotes acid alteration and isochemical leaching of the permeable volcanic rocks, which explains the generally low pH and high total carbon content of waters. Attainment of chemical equilibrium between the rock and the weathering solutions is prevented by commonly low temperature (10 to 28°C) and acid-reducing conditions. The chemical and isotope (C and He) composition of dissolved gases highlights the magmatic origin of the gas phase feeding the aquifer. We show that although the pristine magmatic composition may vary upon gas ascent because of either dilution by a soil-atmospheric component or fractionation processes during interaction with the aquifer, both 13C/12C and 3He/4He measurements indicate the contribution of a magmatic component with a 13C 0‰ and R/Ra of 2.7, which is consistent with data from Vesuvius fumaroles and phenocryst melt inclusions in olivine phenocrysts. A main control of tectonics on gas ascent is revealed by data presented in this paper. For example, two areas of high CO2 release and enhanced rock leaching are recognized on the western (Torre del Greco) and southwestern (Torre Annunziata–Pompeii) flanks of Vesuvius, where important NE-SW and NW-SE tectonic structures are recognized. In contrast, waters flowing through the northern sector of the volcano are generally colder, less saline, and CO2 depleted, despite in some cases containing significant concentrations of magmaderived helium. The remarkable differences among the various sectors of the volcano are reconciled in a geochemical interpretative model, which is consistent with recent structural and geophysical evidences on the structure of Somma-Vesuvius volcanic complex.
    Description: -European Union, -Ministero dell’Universita’ e della Ricerca Scientifica e Tecnologica; -CNR–Gruppo Nazionale per la Vulcanologia.
    Description: Published
    Description: 963–981
    Description: partially_open
    Keywords: isotopes ; water chemistry ; dissolved gases ; 03. Hydrosphere::03.02. Hydrology::03.02.03. Groundwater processes ; 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 ; 03. Hydrosphere::03.04. Chemical and biological::03.04.07. Radioactivity and isotopes ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 9
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    Geochemical monitoring of groundwaters (1998-2001) at Vesuvius volcano (Italy) (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: This work presents the results of hydrogeochemical studies carried out at Vesuvius during the period May 1998 - December 2001, mostly focusing on compositional time variations observed during this time. Based on their chemistry, groundwater samples are distinguished into two groups, 1 and 2, representative of water circulation in the southern and northern sectors of the volcano, respectively. Waters from group 1 are typically more acidic, warmer,and more saline than those of group 2. They also have higher CO2 and CH4 contents, attributed to enhanced input of deep-rising volatiles and prolonged water-rock interactions. Time-series highlight the fairly constant chemical composition of the entire aquifer. Groundwater temperature, pH, bicarbonate content and dissolved CO2 display quite stable values in the study period, particularly in deep wells (piezometric level more than 100 m deep). Shallower water bodies present more evident temporal variations, related to seasonal and anthropogenic effects. This paper also describes some important variations in water chemistry which had occurred by the time of the seismic event in early October 1999, particularly in the Olivella spring located on the northern flank of the volcano. At this site, a great decrease in water pH and redox potential, and increased dissolved CO2 contents and 3He/4He ratios were observed. These changes in chemical and isotope composition support the hypothesis of an input of magma-derived helium and carbon dioxide into the aquifer feeding the Olivella spring by the time of the earthquake.
    Description: Published
    Description: 81-104
    Description: partially_open
    Keywords: Vesuvius ; volcanic surveillance ; groundwater ; hydro-geochemistry ; oxygen-18 ; 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::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 10
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    Chemical and isotopic equilibrium between CO2 and CH4 in fumarolic gas discharges: generation of CH4 in magmatic-hydrothermal systems (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The chemical and isotopic composition of fumarolic gases emitted from Nisyros Volcano, Greece,and of a single gas sample from Vesuvio, Italy, was investigated in order to determine the origin of methane (CH4) within two subduction-related magmatic-hydrothermal environments. Apparent temperatures derived from carbon isotope partitioning between CH4 and CO2 of around 340°C for Nisyros and 470°C for Vesuvio correlate well with aquifer temperatures as measured directly and/or inferred from compositional data using the H2O-H2-CO2-CO-CH4 geothermometer. Thermodynamic modeling reveals chemical equilibrium between CH4, CO2 and H2O implying that carbon isotope partitioning between CO2 and CH4 in both systems is controlled by aquifer temperature. N2/3He and CH4/3He ratios of Nisyros fumarolic gases are unusually low for subduction zone gases and correspond to those of midoceanic ridge environments. Accordingly, CH4 may have been primarily generated through the reduction of CO2 by H2 in the absence of any organic matter following a Fischer-Tropsch-type reaction. However, primary occurrence of minor amounts of thermogenic CH4 and subsequent re-equilibration with co-existing CO2 cannot be ruled out entirely. CO2/3He ratios and 13CCO2 values imply that the evolved CO2 either derives from a metasomatized mantle or is a mixture between two components, one outgassing from an unaltered mantle and the other released by thermal breakdown of marine carbonates. The latter may contain traces of organic matter possibly decomposing to CH4 during thermometamorphism.
    Description: European community
    Description: Published
    Description: 2321–2334
    Description: partially_open
    Keywords: fumarolic gases ; hydrothermal systems ; chemical and isotopic equilibrium ; 03. Hydrosphere::03.04. Chemical and biological::03.04.06. Hydrothermal systems ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 11
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    Water speciation and Sr isotopic exchange during water-melt interaction: a combined NMR-TIMS study on the Cretaio Tephra (Ischia Island,south Italy) (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: In order to improve the microscopic understanding of the water-magma interaction process during explosive volcanism,volcanic glasses representative of deposits with sedimentological characteristics suggesting different water/melt ratios were studied by a combination of the nuclear magnetic resonance (NMR) and TIMS methods. The glasses were separated from pumices of two surge layers and one fallout bed of the Cretaio Tephra (Ischia Island,Italy), which is the product of an explosive eruption that occurred at Ischia in the second century BC. The 29Si CP^MAS NMR experiments indicate the occurrence of 1H^29Si dipolar couplings in glasses from the phreatomagmatic activity, suggesting the presence of hydrogen atoms in proximity of silicon atoms. This feature is not detected in the glass from the deposit of the magmatic explosion. 1H MAS NMR spectra reveal different peaks attributed to different hydrous species characterized by different motional properties. These include ‘rigid’ H2O groups isolated in the glass structure, more mobile water species and possibly structural hydroxyl groups. 1H MAS NMR spectra recorded after deuteration experiments of the glass at a temperature up to 300‡C revealed that the exchange reactions of the D2O vapor with hydrogen were limited to the most mobile water species,possibly on vesicle surfaces or in channels. The hydrogen concentration linearly correlates with the 87Sr/86Sr isotope ratio in glasses,suggesting isotopic tracer exchanges between the Sr dissolved in the water vapor and the Sr in the silicon-oxygen network during hydration. It is proposed that the uprising melt interacted with a hydrothermal system of seawater-derived fluids,characterized by relatively high Sr isotopic composition.
    Description: Published
    Description: 311-320
    Description: partially_open
    Keywords: Ischia ; Cretaio Tephra ; Water-melt interaction ; Nuclear magnetic resonance ; Sr isotopes ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 12
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    Quantitative analysis of the tremor wavefield at Etna Volcano, Italy (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The properties of volcanic tremor wavefield at Mt. Etna Volcano, Italy, are investigated using data from two dense, smallaperture arrays of short-period seismometers deployed on the North and South flank of the volcano. Spectral analysis shows that most of the seismic energy is associated to several, narrow spectral peaks spanning the 1–5 Hz frequency band. Analysis of simultaneous recordings evidences that most of these peaks are common to different sites, thus suggesting a source effect as the origin of this energy. Frequency-slowness analyses evidence a complex wavefield, where body- and surface-waves alternatively dominate depending on the frequency band and component of motion taken into account. Surface waves are found to dominate at frequencies below 1 Hz and above 3 Hz. Conversely, the 0.8–2.3 Hz vertical- and radial-component wavefields at both arrays exhibit a nondispersive nature, with apparent velocities spanning the 1–2 s/km range. Particle motion analysis suggests these arrivals are associated to both P- and SV-waves inciding at shallow angles. At the northern array, back-azimuths of these waves encompass the whole summit crater area. At the southern array, back-azimuths are instead clustered around a direction pointing about 500 m east of the SE crater. At frequency around 4 Hz, the dominant direction of wave propagation at the southern site shifts about 30jW, pointing to the Bocca-Nuova/Voragine craters, and concordance of location is found with the source imaged by the northern array. The 0.8–2.3 Hz transverse-component of motion depicts velocities of about 0.5 km/s, a value which is about three times lower than those associated to the vertical and radial components. Results from polarization analyses at the two array sites depict the dominance of horizontal, linear particle motion oriented transversally with respect to the source direction. Polarization ellipsoids at the stations of the sparse network all depict a quasi-horizontal setting. With two exceptions, the direction of particle motion is always oriented tangentially to the summit volcanic edifice. The origin of the large transverse motion observed at the two array sites is thus attributed to SH waves generated by free-surface interaction of waves impinging the concave topography. The correlation method is used to derive the dispersion properties of short-period (0.5–5 Hz) Rayleigh waves, from which the shallow shear-wave velocity structures are derived for beneath the two semicircular arrays. Using a probabilistic approach, we invert slowness data measured at the two dense arrays for retrieving source location and extent. The joint inversion of slowness data from the two arrays point to different sources. This observation is interpreted in terms of ray bending associated to lateral heterogeneity and/or strong topographic effects on wave propagation. Once the propagation effects are taken into account, the most probable source locations are associated to a shallow region encompassing the summit craters and the eruptive fissures active at the time of the experiment (September 1999).
    Description: Published
    Description: 223-245
    Description: partially_open
    Keywords: Mount Etna ; Volcanic tremor ; Volcanic seismicity ; Seismic monitoring ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 13
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    Structural and rheological constraints on source depth and overpressure estimates at the Campi Flegrei caldera, Italy (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The 1982-84 unrest episode at Campi Flegrei (CF) caldera, Italy, was characterized by huge deformation (more than 1.5 m uplift) concentrated inside the caldera. According to point source isotropic models in homogeneous elastic and visco-elastic half-spaces, the source depth is very shallow (about 3 km). If the source radius is about 1 km this implies that magma is at a depth of 2 km depth. However, several independent observations show that the top of the magma chamber at CF must be deeper than 4 km. This paper investigates how the inferred source depth increases when rigidity heterogeneities (obtained through seismic tomography at CF) are considered and when the long-term deformation takes place under drained conditions. Finite element models indicate that overpressure needed at the source to reproduce the 1.5 m maximum uplift is however beyond typical rock strength values. This evidence, together with the high thermal anomalies, the presence of fluids and the low cohesion of tuffs filling the caldera, suggests the use of elastoplastic constitutive laws. For elastoplastic behavior, the same deformation is obtained using a deeper source (with center at 5 km depth) and a lower overpressure (than required by elastic models). The plastic deformation concentrates both at the source boundaries and above the source, where seismic activity has been recorded. These results indicate that the rheological properties of the shallow crust of CF have important implications for hazard estimate during unrest episodes.
    Description: INGV-Gruppo Nazionale per la Vulcanologia; Ministero dell'Istruzione Università e Ricerca- FIRB Project
    Description: Published
    Description: 14
    Description: reserved
    Keywords: finite element modelling ; Campi Flegrei ; surface deformation ; plasticity ; rheological layering ; overpressure source ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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    The role of extensional structures on experimental calderas and resurgence (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The structure and shape of collapses and resurgences is often controlled by pre-existing discontinuities, such as normal faults in rift zones. In order to study the role of extensional structures on collapse and resurgence, we used analogue models. Dry sand simulated the brittle crust; silicone, located at the base of the sand-pack, simulated magma. In the experiments, regional extension pre-dated collapse or resurgence, forming normal faults in a grabenlike structure; the graben was filled with additional sand, simulating post-rift deposits. A piston then moved the silicone downward or upward, inducing collapse or resurgence within the previously deformed sand. The collapses showed an ellipticity (length of minor axis/length of major axis) between 0.8 and 0.9, with the major axis parallel to the extension direction. The partial reactivation of the pre-existing normal faults was observed during the development of the caldera reverse faults, which, conversely to what was expected (from experiments without preexisting extension), became partly inward dipping. Resurgence showed an elongation of the uplifted part, with the main axis perpendicular to the extension direction. At depth, pre-existing normal faults were partly reactivated by the reverse faults formed during resurgence; these locally became outward dipping normal faults. A total reactivation of pre-existing faults was also observed during resurgence. The experiments suggest that the observed elongation of calderas and resurgences is the result of the reactivation of pre-existing structures during differential uplift. Such a reactivation is mainly related to the loss in the coefficient of friction of the sand. The results suggest that elliptic calderas and resurgences in nature may develop even from circular magma chambers.
    Description: Published
    Description: 199-217
    Description: partially_open
    Keywords: Extensional structures ; Caldera ; Resurgence ; Analogue models ; Reactivation ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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    A test on a Neuro-Fuzzy algorithm used to reduce continuous gravity records for the effect of meteorological parameters (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Gravity measurements are utilized at active volcanoes to detect mass changes linked to magma transfer processes and thus to recognize forerunners to paroxysmal volcanic events. Continuous gravity measurements are now increasingly performed at sites very close to active craters, where there is the greatest chance to detect meaningful gravity changes. Unfortunately, especially when used against the adverse environmental conditions usually encountered at such places, gravimeters have been proved to be affected by meteorological parameters, mainly by changes in the atmospheric temperature. The pseudo-signal generated by these perturbations is often stronger than the signal generated by actual changes in the gravity field. Thus, the implementation of well-performing algorithms for reducing the gravity signal for the effect of meteorological parameters is vital to obtain sequences useful from the volcano surveillance standpoint. In the present paper, a Neuro-Fuzzy algorithm, which was already proved to accomplish the required task satisfactorily, is tested over a data set from three gravimeters which worked continuously for about 50 days at a site far away from active zones, where changes due to actual fluctuation of the gravity field are expected to be within a few microgal. After accomplishing the reduction of the gravity series, residuals are within about 15μGal peak-to-peak, thus confirming the capabilities of the Neuro-Fuzzy algorithm under test of performing the required task satisfactorily.
    Description: Published
    Description: 11
    Description: partially_open
    Keywords: Gravimeters ; Exogenous parameter compensation ; Neuro-Fuzzy algorithm ; 04. Solid Earth::04.03. Geodesy::04.03.05. Gravity variations
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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    Seismic source dynamics at Vesuvius volcano, Italy (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: On October 9, 1999 an earthquake of ML =3.6 occurred about 3 km beneath the central cone of Mt. Vesuvius, near Naples, Italy. The event had the highest magnitude recorded for at least 25 years, and possibly since the last eruption of this volcano (1944), and was not accompanied by other geophysical or geochemical changes. The present paper essentially deals with the seismological data collected at Mt. Vesuvius for 29 years before the October 9 earthquake till the end of 2001, and describes the time pattern distribution of seismic slip release and the b-parameter of the Gutenberg^Richter distribution. The self-similarity of the source process is investigated through the scaling law of the seismic spectrum. Results indicate a two-fold pattern of stress release, with high values (up to 100 bar) for earthquakes occurring close to the top of the carbonate basement that underlies the volcano at 2^3 km of depth, and low values (down to 0.1 bar) for the shallow events occurring within the volcanic edifice. The scaling law of the seismic spectrum is non-self-similar, indicating that the source dimensions do not scale with the seismic moment. For this reason the low-magnitude events substantially contribute to the overall cumulative seismic slip release. The bparameter of the Gutenberg^Richter distribution shows a variation around 1980, and a substantial constancy in the other time periods. The presence of extended aquifers, with their tops at about 1 km beneath the crater, favors the hypothesis of the triggering of the shallowest events by water-level changes. This hypothesis is in agreement with the low values of the stress drop measured for the shallowest seismic events. The existence of a carbonate basement with its top at about 2.5 km beneath the crater and the higher stress drops for the deeper events make reasonable the hypothesis that the pre-fractured carbonate basement may be the site of tectonic stress release.
    Description: Published
    Description: 23-39
    Description: partially_open
    Keywords: Vesuvius ; Seismicity ; Seismic source ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 17
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    Thermal and geochemical constraints on the ‘deep’ magmatic structure of Mt. Vesuvius (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: A review of available and new isotopic data on rocks from Mt. Vesuvius together with geophysical and mineralogical data allow us to define a ‘deep’ complex magmatic reservoir where mantle-derived magmas arrive, stagnate and differentiate, and to constrain a thermal model, which describes the history and present state of the reservoir and its surrounding rocks. The top of the reservoir is located at about 8 km depth, and it extends discontinuously down to 20 km depth. The reservoir is hosted in densely fractured continental crustal rocks, where magmas and crust can interact, and, according to thermal modeling results, has been fed more than once in the last 400 ka. The hypothesis of crustal contamination is favored by the high temperatures reached by crustal rocks as a consequence of repetitive intrusions of magma. From the ‘deep’ reservoir magmas rise to form ‘shallow’ magma chambers at different depths, as already known in the literature, where they can undergo low-pressure differentiation and mixing and feed the volcanic activity.
    Description: Published
    Description: 1-12
    Description: partially_open
    Keywords: Magmatic system ; Crustal contamination ; Thermal modeling ; Isotope geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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    Plume chemistry provides insights into mechanisms of sulfur and halogen degassing in basaltic volcanoes (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: This paper deals with sulfur, chlorine and fluorine abundances in the eruptive volcanic plume of the huge October 2002– January 2003 eruption of Mount Etna, aiming at relating the relevant compositional variations observed throughout with changes in eruption dynamics and degassing mechanisms. The recurrent sampling of plume acidic volatiles by filter-pack methodology revealed that, during the study period, S/Cl and Cl/F ratios ranged from 0.1–6.8 and 0.9–5.6, respectively. Plume S/Cl ratios increased by a factor of f10 as volcanic activity drifted from paroxysmal lava fountaining (mid- and late November) to passive degassing and minor effusion (early January), and then decreased to the low values (S/Cl = 0.1) typical of the final stages of the eruption. Parallel variations in chlorine to fluorine ratios were also observed. A theoretical model is proposed for quantitative interpretation of these changes in plume composition. The model calculates the composition of a volatile phase exsolving from an ascending Etna magma, based on knowledge of solubilities and abundances in the undegassed melt of sulfur and halogens [T.M. Gerlach, EOS 72 (1991), 249, 254–255]. According to this model, degassing of Etnean basaltic melt at high pressures and depths (〉100 MPa, 3 km) is likely to release a CO2+H2O-rich vapor phase with S/Cl molar ratios f1. Extensive sulfur and chlorine degassing from the melt would take place at shallower depth ( P 〈 20 MPa, 0.6 km), with S/Cl ratios in the vapor phase increasing as pressure drops to 0.1 MPa. Comparisons between model compositions and volcanic plume data demonstrate that the chemical trends observed during the eruption may be explained by increased degassing due to depressurization of a basaltic magma batch ascending toward the surface.
    Description: Published
    Description: 469-483
    Description: partially_open
    Keywords: magmatic degassing ; volcanic plume ; basaltic eruption ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 19
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    Rapid morphological changes at the summit of an active volcano: reappraisal of the poorly documented 1964 eruption of Mount Etna (Italy) (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: While the eruptive record of Mount Etna is reasonably complete for the past 400 years, the activity of the early and late 1960s, which took place at the summit, is poorly documented in the scientific literature. From 1955 to 1971, the Central and Northeast Craters were the sites of long-lived mild Strombolian and effusive activity, and numerous brief episodes of vigorous eruptive activity, which led to repeated overflows of lava onto the external flanks of the volcano. A reconstruction of the sequence of the more important of these events based on research in largely obscure and nearly inaccessible sources permits a better understanding of the eruption dynamics and rough estimates of erupted volumes and of the changes to the morphology of the summit area. During the first half of 1964, the activity culminated in a series of highly dynamic events at the Central Crater including the opening of a fissure on the E flank of the central summit cone, lava fountains, voluminous tephra emission, prolonged strong activity with continuous lava overflows, and growth of large pyroclastic intracrater cones. Among the most notable processes during this eruption was the breaching of a section of the crater wall, which was caused by lateral pressure of lava ponding within the crater. Comparison with the apparently similar summit activity of 1999 allows us to state that (a) lava overflows from large pit craters at the summit are often accompanied by breaching of the crater walls, which represents a significant hazard to nearby observers, and that (b) eruptive activity in 1999 was much more complex and voluminous than in 1964. For 1960s standards however, the 1964 activity was the most important summit eruption in terms of intensity and output rates for about 100 years, causing profound changes to the summit morphology and obliterating definitively the former Central Crater.
    Description: Published
    Description: 203-218
    Description: partially_open
    Keywords: Mount Etna ; Summit eruption ; Crater morphology and Lava overflows ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
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    Crustal seismic tomography in the Calabrian Arc region, south Italy (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: 27,646 P- and 15,025 S-wave readings obtained from 2238 earthquakes and 84 artificial sources were used to perform tomographic inversion of P velocity and VP/ VS ratio in the crust of Calabrian Arc by Thurber´s inversion algorithm. For this investigation a seismic database with more than twelve-thousand events was built, including all local earthquake data recorded between 1978 and 2001 at all stations of the national and local networks in south Italy. Spread Function computations and checkerboard and restore tests proved higher accuracy of velocity estimates in the upper 40 km beneath Calabrian Arc compared to previous investigations in the same area. The obtained three-dimensional velocity model furnished remarkable improvement of hypocenter locations of the global earthquake dataset (RMS reduction of 38% respect to 1D locations) and greater accuracy in the definition of microplates and tectonic units in the study region. Velocity domains evidenced by our tomography correspond to tectonic units locally identified with geological methods by previous investigators and allow us to better detail their shape and geometry at depth. In particular, at a depth of about 20 km beneath Calabria we detected the deep contact between the overthrusting Tyrrhenian crust and the subducting Ionian slab, improving the accuracy of the current subduction model of the Calabrian Arc region.
    Description: Published
    Description: 297-314
    Description: partially_open
    Keywords: Seismic tomography ; Crustal structure ; Seismicity ; Italy and Tyrrhenian sea ; 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 21
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    The use of IFSAR and classical geodetic techniques for caldera unrest episodes: application to the Campi Flegrei uplift event of 2000 (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Campi Flegrei caldera has a long history of large surface deformation,with isplacements of several meters in the 1970s and early 1980s. Its location within a densely populated urban area underscores the importance of understanding the relationship between large and episodic deformation events and their source mechanisms. The primary observable of the caldera’s activity is its surface deformation. Classical geodetic approaches such as leveling, have been complemented by the more advanced measurements of the Global Positioning System (GPS) and Synthetic Aperture Radar (SAR) interferometry. In this work we focus on the Campi Flegrei caldera uplift event that occurred from early spring to late summer 2000. Our goal is to highlight the potential to integrate interferometric SAR (IFSAR),GPS, and classical leveling data for ground deformation studies and source modeling. We compare models for the deformation source constrained by inversion of the differential IFSAR data (DIFSAR) with the model’s prediction for the GPS and leveling data. Resolution of possible changes in the source mechanism for Campi Flegrei caldera are limited by differences in the temporal,spatial and deformation component strengths of each data set. In the future,overcoming these data deficiencies will be important for resolving the dynamics of volcano systems and for volcanic hazard mitigation.
    Description: Published
    Description: 247-260
    Description: partially_open
    Keywords: Caldera unrest ; Global positioning system ; SAR interferometry ; Volcano deformation ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 22
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    Fluctuation analysis of the hourly time variability of volcano-magnetic signals recorded at Mt. Etna Volcano, Sicily (Italy) (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The time-correlation properties in the hourly time variability of volcano-magnetic data measured at the active volcano Mt. Etna, Sicily (southern Italy), are investigated by using the detrended fluctuation analysis (DFA). DFA is a data processing method that allows for the detection of scaling behaviors in observational time series even in the presence of nonstationarities. The procedure adopted has revealed unambiguous link between the dynamics of the measured data and the recent eruptive episode of the volcano occurred on October 27, 2002.
    Description: Published
    Description: 1921-1929
    Description: partially_open
    Keywords: MT Etna ; 04. Solid Earth::04.05. Geomagnetism::04.05.04. Magnetic anomalies ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 23
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    Seismoacoustic measurements during the July–August 2001 eruption of Mt. Etna volcano, Italy (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: On July 18, 2001, two main eruptive vents opened on the southern flank of Mount Etna volcano (Italy) at ~2100 m and ~2550 m a.s.l., respectively. The former vent fed mild strombolian activity and lava flows, while the latter represented the main explosive vent, producing strong phreato-magmatic explosions. Explosions at this latter vent, however, shifted to a strombolian style in the following days, before switching back to phreato-magmatic activity towards the end of the eruption, which ended on August 9, 2001. On August 3, a small seismoacoustic array was deployed close to the eruptive vents. The array was composed of three stations, which recorded seismic and infrasonic waves coming from both of the eruptive vents. A further seismoacoustic station, equipped with a thermal-infrared sensor, was also installed several kilometers north of the first array. Seismic signals relating to the strombolian activity at the 2100-m vent were characterized by a strong decompression at the source. Analysis of the time delays between seismic, infrasonic and infrared event onsets also revealed that ejection velocities during explosions from both vents were subsonic. Time delays between the onset of explosive events apparent in the infrared and infrasound data indicated that the explosion source at the 2550-m vent was located 220–250 m below the crater rim. In comparison, the depth of the seismic source was estimated to be between 230 and 335 m below the rim. This converts to 120–150 and 130–235 m below the preexisting ground surface. In addition, time delays between seismic and infrasonic signals recorded for the lower (2100 m) vent also revealed a seismic source that was no more than a few tens of meters deeper than the fragmentation surface.
    Description: Published
    Description: 219-230
    Description: partially_open
    Keywords: Mt. Etna ; explosive eruptions ; arrays ; seismic ; infrasonic and thermal data ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
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  • 24
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    Pulsed lava effusion at Mount Etna during 2001 (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Effusion rate and degassing data collected at Mt. Etna volcano (Italy) in 2001 show variations occurring on time scales of hours to months. We use both long- and short-term data sets spanning January to August to identify this variation. The long data sets comprise a satellite- and ground-based time series of effusion rates, and the latter include field-based effusion rate and degassing data collected May 29–31. The satellite-derived effusion rates for January through August reveal four volumetric pulses that are characterized by increasing mean effusion rate values and lead up to the 2001 flank eruption. Peak effusion rates during these 23–57 day pulses were 1.2 m3 s-1 in Pulse 1 (1 Jan–4 Mar), 1.1 m3 s-1 in Pulse 2 (5 Mar–21 Apr), 4.2 m3 s-1 in Pulse 3 (24 Apr–18 Jun), 8.8 m3 s-1 in Pulse 4 (23 Jun–16 Jul), and 22.2 m3 s-1 during the flank eruption (17 Jul–9 Aug). Rank-order analysis of the satellite data shows that effusion rate values during the 2001 flank eruption define a statistically different trend than Etna's persistent activity from Jan 1 to Jul 17. Data prior to the flank eruption obey a power-law relationship that may define an effusion rate threshold of ~3–5 m3 s-1 for Etna's typical persistent activity. Our short-term data coincide with the satellite-derived peak effusion period of Pulse 3. Degassing (at-vent puff frequency) shows a general increase from May 29 to 31, with hour-long variations in both puff frequency and lava flow velocity (effusion rate). We identify five 3–14 h degassing periods that contain 26 shorter (19–126 min-long) oscillations. This variation shows some positive correlation with effusion rate measurements during the same time period. If a relationship between puff frequency and effusion rate is valid, we propose that their short-term variation is the result of changes in the supply rate of magma to the near-vent conduit system. Therefore, these short-term data provide some evidence that the clear weeks- to months-long variation in Etna's effusive activity (January–August 2001) was overprinted by a minutes- to hour-scale oscillation in shallow supply.
    Description: Published
    Description: 231-246
    Description: partially_open
    Keywords: effusion rate ; degassing ; oscillation ; shallow supply and Etna ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 25
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    Structural features of an active strike-slip fault on the sliding flank of Mt. Etna (Italy) (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The strike-slip Pernicana fault system (PFS) was activated along the eastern flank of Mt. Etna during an earthquake in September 2002 and, one month later, during the eruption of the NE Rift. Structural and volcanological data suggest that the PFS was activated as a result of the slide of the NE flank of Etna. This activation produced surface fracturing on walls and on paved and unpaved roads. The segments of the PFS, arranged in a right stepping en échelon configuration, show (a) an inverse proportion between length and frequency; (b) fractal behavior over scales of 10−2 –101 m, between their length, overstep and overlap; (c) consistent strike with regard to their fault array; and (d) a progressive eastward decrease in the displacement, along the smallest faults. The consistent geometric and kinematic features of the PFS, related to the sector collapse of Etna, are similar to those of faults in strike-slip settings.
    Description: Published
    Description: 343-355
    Description: partially_open
    Keywords: Active faulting ; Strike-slip faults ; Fractal behavior ; Volcano collapse ; Mt. Etna ; Pernicana fault system ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 26
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    Near- and far-field survey report of the 30 December 2002 Stromboli (Southern Italy) tsunami (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: In May 2002, Stromboli–one of the two active volcanoes in the Aeolian Islands (southern Tyrrhenian sea)–entered a new phase of explosive activity, initially characterized by gas and ash emission from the summit craters. On 30 December 2002, a massive submarine landslide, followed by a subaerial one from the elevation of about 650 m above sea level (a.s.l.), detached from the submerged part of the northwest slope of Stromboli island producing a tsunami. This huge mass movement was recorded by the INGV seismic stations installed, respectively, at Stromboli and Panarea. In the following days, a working group of INGV researchers and technicians was organized in order to perform a field survey of the tsunami effects in the near-field—including all the Aeolian Islands. Meanwhile, a survey in the far-field was planned, along the coastline of Campania and Sicily, where the effects of the 30 December tsunami were observed but not directly quantified. Visible material effects of the 30 December tsunami could be observed only along the northeast coast of Stromboli island, inundated by the wave, with run-up heights locally up to several meters. Many buildings were severely damaged. On the other Aeolian Islands and in the far-field, the effects of the sea wave were documented only through eyewitness accounts. To ensure a coherent collection of these accounts, a standard interview form, based on the advice of the Intergovernmental Oceanographic Commission (IOC), was used. A databank of all observations, measurements, interview forms and photographs was compiled in order to provide a useful base to test computer simulations, hazard analyses and damage scenarios. Additional information was also made available at the EMERGEO link of INGV web pages http://www.ingv.it/ emergeo and http://www.ov.ingv.it.
    Description: Published
    Description: 93-106
    Description: partially_open
    Keywords: Aeolian Islands ; Far-field ; Stromboli ; Near-field ; Field survey ; Tsunamis ; 04. Solid Earth::04.04. Geology::04.04.04. Marine geology ; 04. Solid Earth::04.04. Geology::04.04.03. Geomorphology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 27
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    Petrologic monitoring of glasses in the pyroclastites erupted in February 2004 by the Stromboli Volcano, Aeolian Islands, Southern Italy (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Following an increase of eruptive activity at Stromboli summit craters in February 2004, we promptly carried out SEM-EDS microanalyses and textural observations on samples of lapilli to check the possible occurrence of Low Porphyritic magma (LP magma), a forerunner of hazardous paroxysmal eruptions. The acquired results suggest that all erupted glasses belong to the High Porphyritic magma (HP magma), which characterizes the typical mild explosive activity of the volcano.
    Description: Published
    Description: 339-343
    Description: partially_open
    Keywords: petrologic monitoring ; Stromboli volcano ; 04. Solid Earth::04.04. Geology::04.04.05. Mineralogy and petrology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 28
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    H2S fluxes from Mt. Etna, Stromboli, and Vulcano (Italy) and implications for the sulfur budget at volcanoes (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: We present here new measurements of sulfur dioxide and hydrogen sulfide emissions from Vulcano, Etna, and Stromboli (Italy), made by direct sampling at vents and by filter pack and ultraviolet spectroscopy in downwind plumes. Measurements at the F0 and FA fumaroles on Vulcano yielded SO2/H2S molar ratios of 0.38 and 1.4, respectively, from which we estimate an H2S flux of 6 to 9 for the summit crater. For Mt. Etna and Stromboli, we found SO2/H2S molar ratios of 20 and 15, respectively, which combined with SO2 flux measurements, suggest H2S emission rates of 50 to 113 and 4 to 8, respectively. We observe that source and plume SO2/H2S ratios at Vulcano are similar, suggesting that hydrogen sulfide is essentially inert on timescales of seconds to minutes. This finding has important implications for estimates of volcanic total sulfur budget at volcanoes since most existing measurements do not account for H2S emission.
    Description: Published
    Description: 1861–1871
    Description: partially_open
    Keywords: H2S atmospheric budget ; volcanic degassing ; 01. Atmosphere::01.01. Atmosphere::01.01.07. Volcanic effects ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 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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    Changes in fluid geochemistry and physico-chemical conditions of geothermal systems caused by magmatic input: The recent abrupt outgassing off the island of Panarea (Aeolian Islands, Italy) (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Hydrothermal systems and related vents can exhibit dramatic changes in their physico-chemical conditions over time as a response to varying activity in the feeding magmatic systems. Massive steam condensation and gas scrubbing processes of thermal fluids during their ascent and cooling cause further compositional changes that mask information regarding the conditions evolving at depth in the hydrothermal system. Here we propose a new stability diagram based on the CO2-CH4-CO-H2 concentrations in vapor, which aims at calculating the temperatures and pressures in hydrothermal reservoirs. To filter gas scrubbing effects, we have also developed a model for selective dissolution of CO2-H2S-N2-CH4-He-Ne mixtures in fresh and/or air-saturated seawater. This methodology has been applied to the recent (November 2002) crisis that affected the geothermal field off the island of Panarea (Italy), where the fluid composition and fluxes have been monitored for the past two decades. The chemical and isotopic compositions of the gases suggest that the volatile elements originate from an active magma, which feeds a boiling saline solution having temperatures of up to 350 C and containing 12 mol CO2 in vapor. The thermal fluids undergo cooling and re-equilibration processes on account of gas-water-rock interactions during their ascent along fracture networks. Furthermore, steam condensation and removal of acidic species, partial dissolution in cold air-saturated seawater and stripping of atmospheric components, affect the composition of the geothermal gases at shallow levels. The observed geochemical variations are consistent with a new input of magmatic fluids that perturbed the geothermal system and caused the unrest event. The present-state evolution shows that this dramatic input of fluids is probably over, and that the system is now tending towards steady-state conditions on a time scale of months.
    Description: Published
    Description: 3045-3059
    Description: partially_open
    Keywords: Submarine degassing ; geothermal system ; gas-water interaction ; gas geothermometry ; 04. Solid Earth::04.01. Earth Interior::04.01.02. Geological and geophysical evidences of deep processes ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.04. Thermodynamics ; 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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  • 30
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    Gas hazard assessment in a densely inhabited area of Colli Albani Volcano (Cava dei Selci, Roma) (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The northwestern flank of the Colli Albani, a Quaternary volcanic complex near Rome, is characterised by high CO2 values and Rn activities in the groundwater and by the presence of zones with strong emission of gas from the soil. The most significant of these zones is Cava dei Selci where many houses are located very near to the gas emission site. The emitted gas consists mainly of CO2 (up to 98 vol) with an appreciable content of H2S (0.8). The He and C isotopic composition indicates, as for all fluids associated with the Quaternary Roman and Tuscany volcanic provinces, the presence of an upper mantle component contaminated by crustal fluids associated with subducted sediments and carbonates. An advective CO2 flux of 37 tons/day has been estimated from the gas bubbles rising to the surface in a small drainage ditch and through a stagnant water pool, present in the rainy season in a topographically low central part of the area. A CO2 soil flux survey with an accumulation chamber, carried out in February-March 2000 over a 12 000 m2 surface with 242 measurement points, gave a total (mostly conductive) flux of 61 tons/day. CO2 soil flux values vary by four orders of magnitude over a 160-m distance and by one order of magnitude over several metres. A fixed network of 114 points over 6350 m2 has been installed in order to investigate temporal flux variations. Six surveys carried out from May 2000 to June 2001 have shown large variations of the total CO2 soil flux (8/25 tons/day). The strong emission of CO2 and H2S, which are gases denser than air, produces dangerous accumulations in low areas which have caused a series of lethal accidents to animals and one to a man. The gas hazard near the houses has been assessed by continuously monitoring the CO2 and H2S concentration in the air at 75 cm from the ground by means of two automatic stations. Certain environmental parameters (wind direction and speed; atm P, T, humidity and rainfall) were also continuously recorded. At both stations, H2S and CO2 exceeded by several times the recommended concentration thresholds. The highest CO2 and H2S values were recorded always with wind speeds less than 1.5 m/s, mostly in the night hours. Our results indicate that there is a severe gas hazard for people living near the gas emission site of Cava dei Selci, and appropriate precautionary and prevention measures have been recommended both to residents and local authorities.
    Description: - GNV funded research project Gas Hazard of Colli Albani
    Description: Published
    Description: 81^94
    Description: partially_open
    Keywords: Colli Albani ; CO2 flux ; H2S ; gas hazard ; 01. Atmosphere::01.01. Atmosphere::01.01.07. Volcanic effects ; 04. Solid Earth::04.01. Earth Interior::04.01.02. Geological and geophysical evidences of deep processes ; 04. Solid Earth::04.03. Geodesy::04.03.06. Measurements and monitoring ; 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::04.08.02. Experimental volcanism ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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    The aquatic geochemistry of arsenic in volcanic groundwaters from southern Italy (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: This paper discusses the abundance, speciation and mobility of As in groundwater systems from active volcanic areas in Italy. Using literature data and new additional determinations, the main geochemical processes controlling the fate of As during gas–water–rock interaction in these systems are examined. Arsenic concentrations in the fluids range from 0.1 to 6940 mg/l, with wide differences observed among the different volcanoes and within each area. The dependence of As content on water temperature, pH, redox potential and major ions is investigated. Results demonstrate that As concentrations are highest where active hydrothermal circulation takes place at shallow levels, i.e. at Vulcano Island and the Phlegrean Fields. In both areas the dissolution of As-bearing sulphides is likely to be the main source of As. Mature Cl-rich groundwaters, representative of the discharge from the deep thermal reservoirs, are typically enriched in As with respect to SO4-rich ‘‘steam heated groundwaters’’. In the HCO3 groundwaters recovered at Vesuvius and Etna, aqueous As cycling is limited by the absence of high-temperature interactions and by high-Fe content of the host rocks, resulting in oxidative As adsorption. Thermodynamic modelling suggests that reducing H2S-rich groundwaters are in equilibrium with realgar, whereas in oxidising environments over-saturation with respect to Fe oxyhydroxides is indicated. Under these oxidising conditions, As solubility decreases controlled by As co-precipitation with, or adsorption on, Fe oxy-hydroxides. Consistent with thermodynamic considerations, As mobility in the studied areas is enhanced in intermediate redox environments, where both sulphides and Fe hydroxides are unstable.
    Description: Published
    Description: 1283–1296
    Description: partially_open
    Keywords: Hydrogeochemistry ; Arsenic ; volcanic groundwaters ; speciation ; 03. Hydrosphere::03.01. General::03.01.01. Analytical and numerical modeling ; 03. Hydrosphere::03.02. Hydrology::03.02.02. Hydrological processes: interaction, transport, dynamics ; 03. Hydrosphere::03.02. Hydrology::03.02.03. Groundwater processes ; 03. Hydrosphere::03.04. Chemical and biological::03.04.03. Chemistry of waters ; 03. Hydrosphere::03.04. Chemical and biological::03.04.06. Hydrothermal systems
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    Spatial variations of seismogenic stress orientations in Sicily, south Italy (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Seismogenic stress orientations are estimated in the lithosphere of Sicily by inversion of 131 local earthquake focal mechanisms (FMs) selected from the literature. An average misfit F = 14.5° between stress tensor and FMs indicates that the entire set of earthquakes is generated by a highly heterogeneous stress field. Detailed analysis of stress tensors and related earthquake misfits obtained for tens of subsets based on spatial separation of data allowed us to identify two main stress domains in the study region: (i) a compressional domain, including Etna, western Sicily and the southern Tyrrhenian sea offshore Sicily, where the σ1 orientation roughly changes from NW–SE in the Etna area and western Sicily to NNE–SSW at the northeastern edge of the domain (Eolian Islands) and (ii) an extensional domain in northeastern Sicily between the Eolian Islands and Etna, where σ3 is oriented analogously to previously estimated in the easterly confining extensional area of the Messina Straits. General agreement is found between this stress pattern and the GPS crustal displacement vectors reported in the most recent literature for the study region. Moreover, stress inversion enables us to locate the extensional domain more accurately than the presently available GPS data. Finally, the stress orientations estimated in the southern and western sectors of the study area (Etna and western Sicily on and offshore) match well with the displacement fields predicted for Sicily by large-scale models of plate motion, conversely a mismatch is observed in the northeastern sector (Eolian Islands and northeastern Sicily). We suggest that the joint action of Africa–Eurasia convergence and Ionian subduction trench retreat (rollback of the subducting slab) may explain the stress pattern detected in Sicily in the present study. Work for computation of a finite-element regional geodynamic model based on geophysical and geological data collected over the last few years has recently started with the purpose of quantitatively checking this hypothesis.
    Description: Published
    Description: partially_open
    Keywords: Crustal seismicity ; Seismogenic stress ; Sicily ; Italy ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk
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  • 33
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    Diffuse degassing of carbon dioxide at Somma-Vesuvius volcanic complex (Southern Italy) and its relation with regional tectonics (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: A systematic survey of soil CO2 concentrations was carried out on the flanks of Somma^Vesuvius volcano in order to constrain possible pathways responsible of carbon dioxide diffuse degassing taking place during the present state of quiescence. Measurements were performed at 1162 sites in late winter^spring 2000,highlighting that soil CO2 concentrations range from 50 to 10500 ppmV. A statistical analysis was developed in order to define the threshold value of anomaly and separate the biogenic CO2 component,produced by soil respiration,from the inorganic component of deep provenance. A computer routine was also elaborated to interpret the grid of CO2 anomalous concentration values and define the actual location,orientation and length of degassing structures. The results obtained by this procedure reveal a main control of the regional stress field on the patterns of gas migration. The identified degassing lineaments are typically oriented along the Apenninic (NW^SE) and anti-Apenninic (NE^SW)trends,which are known to govern the past geological and structural evolution of the Campanian Plain and present seismicity and deformation pattern of Mount Vesuvius. A main degassing area was recognized on the eastern and southern flanks of the volcano,which likely relates to the geometry of the underlying carbonate basement,reaching its top (500 m depth) in this sector of the volcano.
    Description: Published
    Description: 55-79
    Description: partially_open
    Keywords: Somma-Vesuvius ; CO2 degassing ; Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases
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  • 34
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    The role of hydrothermal fuids in triggering the July-August 2000 seismic swarm at Campi Flegrei, Italy:evidence from seismological and mesostructural data (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: This study presents a detailed analysis and interpretation of the seismicity that occurred on July 2-7 and August 22, 2000, during a ground uplift episode which started on March 2000 at Solfatara crater, Campi Flegrei. Earthquakes are located using a probabilistic grid-search procedure acting on a 3-D heterogeneous earth structure. The mainshock of the July swarm depicts a spectrum characterized by a few narrow peaks spanning the 1^5-Hz frequency band. For this event, we hypothesize a direct involvement of magmatic fluids in the source process. Conversely, the spectra of the August events are typical of shear failure. For these latter events, we evaluate the source properties from P-and Swave displacement spectra. Results for the most energetic shocks (Md around 2) yield a source radius in the order of 100 m and stress drop around 10 bars, in agreement with most of the earthquakes that occurred during the 1982-1984 bradyseismic crises. For the August swarm we identify two clusters of similar earthquakes. Application of highresolution relative location techniques to these events allows for the recognition of two parallel alignments trending NE^SW. The relationship among source dimension and relative location evidences overlapping of sources. This may be interpreted in terms of either a heterogeneous stress field or a lubrication process acting over the fault surface. For a selected subset of the August events, we also analyze the splitting of the shear waves: results are indicative of wave propagation through a densely fractured medium characterized by a distribution of cracks oriented NE-SW. The pattern of faulting suggested by relative locations and shear-wave splitting is not consistent with the surface trace of NW^SE striking faults. However, a detailed mesostructural analysis carried out over the Solfatara area indicated the occurrence of two main crack systems striking NW-SE and NE-SW. This latter system shows a strike consistent with that derived from seismic evidence. Results from a stress analysis of the crack systems indicate that a fluid overpressure within the NW-SE-striking faults is able to form NE-SW cracks. We found that the pressure of fluids Pf required to activate the NW-SE faults is less than cHmin, while the Pf value required to open the NE-SW cracks is higher than cHmax. Our main conclusions are: (a) the Solfatara area is affected by two orthogonal fracture systems, and the fluid pathway during the 2000 crisis mainly occurred along the NNE-SSW/NE-SW-striking crack system; (b) the July seismicity is associated to the upward migration of a pressure front triggered by an excess of fluid pressure from a small-size magmatic intrusion; conversely, the August events are associated to the brittle readjustment of the inflated system occurring along some lubricated structures.
    Description: Published
    Description: 229-246
    Description: partially_open
    Keywords: Seismicity ; Hydrothermal fuids ; Fuid pressure ; Faults ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis
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  • 35
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    Birth, growth and morphologic evolution of the `Laghetto´ cinder cone during the 2001 Etna eruption (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: We have undertaken detailed observations of the formation of the `Laghetto´ cinder cone, a new cone that formed during a 2-week period of intense activity in Piano del Lago, on the upper slopes of Mount Etna in summer 2001. We describe the events leading to the formation of a small graben, the formation of pit craters on the base of the graben, the onset of phreatomagmatic activity, a transition to intense Strombolian activity, and a return to phreatomagmatic activity as the eruption came to an end. We discuss the reasons for these transitions, and describe the morphological development of the cone during these events. Arcuate cracks on the southern part of the cone were related to withdrawal of magma at the end of the eruption. Other slope instabilities that developed during the eruption include the formation of small radial grain flows on the outer flanks of the cone and the collapse into the crater of part of the crater rim. Some of the failure planes we observed were first identified using a FLIR TM 695 thermal infrared camera. This is the first time that infrared thermography has been used to detect instability of volcanic structures. Results obtained during this test case demonstrate that thermal cameras are a very useful tool for studies of volcanic instability.
    Description: Published
    Description: 225-239
    Description: partially_open
    Keywords: Etna volcano ; cinder cone ; volcano instability ; thermal images ; phreatomagmatic activity ; 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::04.08.07. Instruments and techniques
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  • 36
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    Oxygen isotope composition of natural waters in the Mt Etna area (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Oxygen isotopes of both rainwater and groundwater samples from Mt Etna were used to obtain information on recharge areas, flow paths, and the origin of wet air masses. Oxygen isotope composition was determined in rainwater samples collected for a period of 3 years (October 1997–October 2000), in 11 rain-gauges distributed along the flanks of Mt Etna from sea level to 2900 m of altitude. Values ranged from 213.8 to þ 1.9‰, the lowest values being measured at higher altitudes and/or during cooler periods. For rain-gauges located from sea level up to 1000 m altitude, volume weighted values defined an isotopic gradient of 22.7‰/km, which is in the range observed in the Mediterranean area. Higher-altitude gauges yielded a much lower gradient (20.6‰/km), probably due to the fact that vapour condensing at higher altitudes was mixed with an 18O-rich volcanic component deriving from the huge vapour output of the summit craters. The oxygen isotope composition of about 210 groundwater samples collected all around the volcano ranged from 29.3 to 25.0‰. The higher values measured on the eastern flank indicated that recharge occurs at lower altitudes on this flank. The low variability (0.30–0.65‰) of the monthly values gathered from 14 groundwater sampling points over a period of 2 years indicates that the groundwater system is isotopically well mixed. Some long-term trends may be explained by variations in annual recharge, due to the prevalent isotope composition of wet air masses.
    Description: National Group for Volcanology (G.N.V.), Italy.
    Description: Published
    Description: 282–299
    Description: partially_open
    Keywords: Isotope hydrology ; d18O ; Groundwater ; Rainwater ; Mt Etna ; 03. Hydrosphere::03.02. Hydrology::03.02.02. Hydrological processes: interaction, transport, dynamics ; 05. General::05.02. Data dissemination::05.02.04. Hydrogeological data
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    The influence of conduit processes on changes in style of basaltic Plinian eruptions: Tarawera 1886 and Etna 122 BC (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Basaltic volcanism is most typically thought to produce effusion of lava, with the most explosive manifestations ranging from mild Strombolian activity to more energetic fire fountain eruptions. However, some basaltic eruptions are now recognized as extremely violent, i.e., generating widespread phreatomagmatic, subplinian and Plinian fall deposits. We focus here on the influence of conduit processes, especially partial open-system degassing, in triggering abrupt changes in style and intensity that occurred during two examples of basaltic Plinian volcanism. We use the 1886 eruption of Tarawera, New Zealand, the youngest known basaltic Plinian eruption and the only one for which there are detailed written eyewitness accounts, and the well-documented 122 BC eruption of Mount Etna, Italy, and present new grain size and vesicularity data from the proximal deposits. These data show that even during extremely powerful basaltic eruptions, conduit processes play a critical role in modifying the form of the eruptions. Even with very high discharge, and presumably ascent, rates, partial open-system behaviour of basaltic melts becomes a critical factor that leads to development of domains of largely stagnant and outgassed melt that restricts the effective radius of the conduit. The exact path taken in the waning stages of the eruptions varied, in response to factors which included conduit geometry, efficiency and extent of outgassing and availability of ground water, but a relatively abrupt cessation to sustained high-intensity discharge was an inevitable consequence of the degassing processes.
    Description: Published
    Description: 1-14
    Description: partially_open
    Keywords: basaltic Plinian eruption ; Etna ; Tarawera and explosive volcanism ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
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    Information content and K-entropy of the present geomagnetic field (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Concepts of information theory are applied to global models of the geomagnetic field B of the last century. The temporal behavior of information content suggests that B is in a chaotic state with characteristic times close to those of its westward drift and of the convective overturn in the outer core and the secular variation shows a comparable characteristic time of predictability. The main implication of these results is the suggestive hypothesis that a possible geomagnetic reversal or excursion is currently in progress.
    Description: Published
    Description: 269-275
    Description: partially_open
    Keywords: information theory ; Kolmogorov entropy ; geomagnetic field ; geomagnetic reversals ; 04. Solid Earth::04.05. Geomagnetism::04.05.02. Geomagnetic field variations and reversals
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  • 39
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    Volcanomagnetic changes accompanying the onset of the 2002–2003 eruption of Mt. Etna (Italy) (2005)
    Elsevier
    Details
    Publication Date: 2017-04-03
    Description: Remarkable changes in the local magnetic field were associated with the onset of the 2002–2003 flank eruption at Mt. Etna. After differential magnetic field measurements were filtered from the external noise by using adaptive filters, we recognized two stages in the total intensity changes, which are closely related to different volcanic events: (a) rapid variations of about 4–5 nT associated with October 26 seismic swarm recorded beneath the summit craters; (b) step-like variations of 9–10 nT coincident with October 27 eruptive fissures opening up in the north flank. These observations are generally consistent with those calculated from simple magnetic models of these volcanic processes, in which the magnetic changes are generated by stress redistribution due to magmatic intrusions at different depth. The magnetic data not only allow the timing of the intrusive event to be described in greater detail but also, together with other volcanological and geophysical evidences, permit some constraints to be set on the characteristics of propagation of a shallow dike. Firstly, at around midnight on 26 October magma was rapidly injected to a depth of 3–4 km just below the summit craters. Secondly, after 1:00 on 27 October, continued intrusion magma occurred upward and culminated a few hundred meters below the free surface fractured along a N–E direction. Thirdly, at about 2:28, magma gave rise to an explosive fissural vent at the northern base of the NE crater near 3000 m a.s.l. Finally, at about 5:00, the first eruptive fissure became active along the eastern border of the NE rift at 2500 m a.s.l. The rate of growth of the magnetic anomalies, moreover, leads to the interpretation that the magmatic intrusion travelled northward from base of the NE crater to the NE rift at approximately 14 m/min.
    Description: Published
    Description: 1-14
    Description: partially_open
    Keywords: eruptions ; monitoring ; magnetic methods ; volcanomagnetic modeling ; Mt. Etna ; 04. Solid Earth::04.05. Geomagnetism::04.05.04. Magnetic anomalies ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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    The buried caldera of Misti volcano, Peru, revealed by combining a self-potential survey with elliptic Fourier function analysis of topography (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: This survey proposes a new approach to identify buried caldera boundaries of a volcanic cone, combining (1) a systematic elliptic Fourier functions (EFF) analysis on the contour lines based on the external shape of the edifice with (2) self-potential (SP) measurements on volcano flanks. The methodology of this approach is to investigate the relationships between (1) vertical morphological changes inferred from EFF analysis and (2) lateral lithological transition inside the edifice inferred from SP/elevation gradients. The application of these methods on Misti volcano in southern Peru displays a very good correlation. The three main boundaries evidenced by hierarchical cluster analysis on the contour lines coincide with the two main boundaries characterised by SP signal and with a secondary SP signature related with a summit caldera. In order to explain these results showing a very good correlation between morphologic and lithologic changes as function of elevation, caldera boundaries have been suggested. The latter would be located at an average elevation of (1) 4350–4400 m, (2) 4950–5000 m, and (3) 5500– 5550 m. For the lowest boundary in elevation, the coincidence with the lateral extension of the hydrothermal system inferred from SP measurements suggests that caldera walls act as a barrier for lateral extension of hydrothermal systems. In the summit area, the highest boundary has been related with the summit caldera, inferred by a secondary SP minimum and geological evidence.
    Description: - Institut de Recherche pour le Développement (IRD) - Instituto Geofisico del Peru´ (IGP).
    Description: Published
    Description: 283– 297
    Description: partially_open
    Keywords: caldera ; elliptic Fourier functions ; geomorphology ; self-potential ; Misti volcano ; Peru ; 03. Hydrosphere::03.02. Hydrology::03.02.02. Hydrological processes: interaction, transport, dynamics ; 03. Hydrosphere::03.02. Hydrology::03.02.03. Groundwater processes ; 03. Hydrosphere::03.02. Hydrology::03.02.04. Measurements and monitoring ; 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::04.01. Earth Interior::04.01.02. Geological and geophysical evidences of deep processes ; 04. Solid Earth::04.02. Exploration geophysics::04.02.04. Magnetic and electrical methods ; 04. Solid Earth::04.04. Geology::04.04.03. Geomorphology ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.04. Geology::04.04.11. Instruments and techniques ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 05. General::05.02. Data dissemination::05.02.04. Hydrogeological data ; 05. General::05.05. Mathematical geophysics::05.05.99. General or miscellaneous ; 05. General::05.08. Risk::05.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 41
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    First appraisal to define prospective seismogenic sources from historical earthquake damages in southern Upper Rhine Graben (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The southern portion ofthe Upper Rhine Graben, a major oblique rift among France, Germany and Switzerland, shows a weak instrumental seismic record despite its remarkable physiographic imprint within the Northern Alpine foreland. Since traces of active deformation can be found in this region and based on experience in other European areas with high seismic hazard and dense population, we searched for past earthquakes recorded in historical catalogues. Based on the fact that tectonic deformation cumulates through geological time and considering that long-term effects tend to leave characteristic signatures on present-day landscape arrangement, our goal was to identify faults that could have caused the damage of recorded historical events. We isolated five main earthquakes, ofmoderate Richter magnitude, essentially located on the E flank of the graben (as is the case with recent seismic activity). To such events, we were able to associate a specific prospective structure through the use ofa procedure thus far successfully employed in Southern European contexts. We concentrated on three events which showed (a) notable sensitivity to the density of the historical felt reports and (b) accordance with on-going subtle deformation pattern. Another, most relevant earthquake (M 5.5) yielded a promising match with the known deformation network in the region. As a template to better constrain earthquake cycle and damage potential, historical seismicity offers an invaluable tool, since it contains a specific record, although not always unambiguous. Cross-checking such data with pertinent geological information allows to devise a realistic fault geometry capable of being responsible for a specific seismic event.
    Description: Published
    Description: 403-425
    Description: open
    Keywords: historical seismicity ; seismogenic sources ; Upper Rhine Graben ; 04. Solid Earth::04.06. Seismology::04.06.05. Historical seismology
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  • 42
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    2001 flank eruption of the alkali- and volatile-rich primitive basalt responsible for Mount Etna's evolution in the last three decades (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Since the early 1970s enhanced eruptive activity of Mount Etna has been accompanied by selective geochemical changes in erupted lavas, among which a gradual increase of alkalis whose origin is still debated. Here we provide further insight into the origin of this recent evolution, based on a detailed study of the chemistry and dissolved volatile content of melt inclusions trapped in olivine crystals of unusual plagioclase-poor primitive basalt that was extruded during a highly explosive flank eruption in July–August 2001. Two types of lava were erupted simultaneously along a N–S fracture system. Trachybasalts from the upper vents (2950–2700 m) were simply drained out by fracturing of the central volcanic conduit. They are identical to summit crater lavas and contain Mg-poor olivines (Fo70–72) with evolved and volatile-poor melt inclusions that represent late-stage crystallisation during shallow open conduit degassing. In contrast, plagioclase-poor basalt (80% of total) extruded through the lower vents (2550–2100 m) derived from lateral dyke intrusion of a more primitive and volatile-rich magma across the sedimentary basement. This primitive melt is best preserved in rare Fo82.4–80.5 skeletal olivines present in lapilli deposits from the most powerful activities at the 2550 m vent. Its high dissolved contents of H2 O (3.4 wt.%), CO2 (0.11 to 0.41 wt.%), S (0.32 wt.%), Cl (0.16 wt.%) and F (0.094 wt.%) point to its closed system ascent from ∼400 to 250 MPa (∼12 to 6.5 km depth b.s.l.). However, the predominance of euhedral olivine phenocrysts with common reverse zoning (cores Fo76–78 and rims Fo78–80) and decrepited inclusions shows that most of the erupted basalt derived from a slightly more evolved, crystallizing body of the same magma that was invaded by the uprising primitive melt prior to erupting. The few preserved inclusions in these olivines indicate pre-eruptive storage of that magma body at about 5 km depth b.s.l., in coherence with seismic data. We propose that the 2001 flank eruption resulted from gradual overpressuring of Etna's shallow plumbing system due to the influx of volatile-rich primitive basalt that may have begun several months in advance. We find that this basalt is much richer in alkalis (2.0 wt.% K2 O) and has higher S/Cl (2.0) but lower Cl/K and Cl/F ratios than all pre-1970s Etnean lavas (1.4 wt.% K2 O, S/Cl=1.5), as further exemplified by melt inclusions in entrained olivine xenocrysts. Combining these new observations with previously published data, we argue that the 2001 basalt represents a new alkali-rich basic end-member feeding Mt. Etna, only few amount of which had previously been extruded during a 1974 peripheral eruption and, more recently, during brief paroxysmal summit events. Over the last three decades this new magma has progressively mixed with and replaced the former K-poorer trachybasalts filling the plumbing system, leading to extrusion of gradually more primitive and alkali-richer lavas. Its geochemical singularities cannot result from shallow crustal contaminations. Instead, they suggest the involvement of an alkali-richer but Cl-poorer arc-type component during recent magma genesis beneath Etna.
    Description: Published
    Description: 1-17
    Description: partially_open
    Keywords: Mt. Etna ; volatiles ; degassing ; eruptive mechanism ; magma geochemistry ; 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::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data
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  • 43
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    Development of tumuli in the medial portion of the 1983 aa flow-field, Mount Etna, Sicily (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: A number of tumuli formed on the aa-dominated lava fan complex which developed in the medial zone of the 1983 flow-field of Mount Etna during the later stages of the eruption. This complex flow-field formed on shallow sloping ground below a scarp between 1900 and 1700 m asl. A major tube system fed a branching tube network in the fan complex. Numerous tumuli and break-outs of lava formed in the fan. Three main types of tumulus are identified: (1) Focal tumuli, which are formed from the break-up and uplift of `old´, thick lava crust and themselves become sustained sites for the distribution of lava both as flows and within distributary tubes. These focal tumuli are significant centres associated with major tubes. (2) Satellite tumuli, which are typically elongate, whale-back shaped features that branch out from focal tumuli. These satellite tumuli were initially lava flows erupted from a focal tumulus. The crust of the flow slowed or came to a halt and the rigid crust became uplifted and fractured, forming a dome-shaped ridge feature. These satellite tumuli continued to be fed from the focal tumulus and became sites of lava emission with numerous break-outs. (3) Distributary tumuli formed on the fan associated with short-lived break-outs from tubes and are relatively simple structures formed from limited effusion of toey lobes and pahoehoe lava. The major tumuli on the fan complex show distinct dilation fractures. The fracture surfaces provide good exposure of the crust and three distinct zones are recognised – an upper zone showing columnar jointing, a middle zone consisting of planar fracture surfaces and a basal zone with distinctive banded planar fracture surfaces showing evidence of both brittle and ductile formation. Using these data a model is proposed for tumulus growth. Field analysis of the fan complex shows how it was fed by a branching tube system, leading to flow thickening, formation of tumuli and numerous ephemeral boccas.
    Description: Published
    Description: partially_open
    Keywords: aa lava flow-field ; Mount Etna ; tumulus ; lava crust and lava tubes. ; 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::04.08.06. Volcano monitoring
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  • 44
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    Unusual sedimentary deposits on the SE side of Stromboli volcano, Italy: products of a tsunami caused by the ca. 5000 years BP Sciara del Fuoco collapse? (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The role of sector collapse in the generation of catastrophic volcanigenic tsunami has become well understood only recently, in part because of the problems in the preservation and recognition of tsunami deposits. Tinti et al. [Tinti, S., Bortolucci, E., Romagnoli, C., 2000. Computer simulations of tsunamis due to sector collapse at Stromboli, Italy. J. Volcanol. Geotherm. Res. 96, 103–128] modeled a tsunami produced by the c. 5,000 years BP collapse of the Sciara del Fuoco on the island volcano Stromboli. Although deposits associated with this event are generally lacking on the island, volcaniclastic breccias on the SE side of the island extending to an elevation above 120 m a.s.l. may have been generated by this tsunami. Deposits above 100 m are dominated by coarse breccias comprising disorganized, poorly sorted, nonbedded, angular to subangular lava blocks in a matrix of finer pyroclastic debris. These breccias are interpreted as a water-induced mass flow, possibly a noncohesive debris flow, generated as colluvial material on steep slopes was remobilized by the return flow of the tsunami wave, the run-up of which reached an elevation exceeding 120 m a.s.l. Finer breccias of subrounded to rounded lava blocks cropping out at 15 m a.s.l. are similar to modern high-energy beach deposits and are interpreted as beach material redeposited by the advancing tsunami wave. The location of these deposits matches the predicted location of the maximum tsunami wave amplitude as calculated by modeling studies of Tinti et al. [Tinti, S., Bortolucci, E., Romagnoli, C., 2000. Computer simulations of tsunamis due to sector collapse at Stromboli, Italy. J. Volcanol. Geotherm. Res. 96, 103–128]. Whereas the identification and modeling of paleo-tsunami events is typically based on the observation of the sedimentary deposits of the tsunami run-up, return flow may be equally or more important in controlling patterns of sedimentation.
    Description: Published
    Description: 329-340
    Description: partially_open
    Keywords: tsunami ; flank collapse ; landslide ; run-up ; return flow ; debris flow ; 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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  • 45
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    Intrinsic and scattering attenuation from observed seismic codas in Southeastern Sicily (Italy) (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: We analyzed about 150 local earthquakes recorded in Southeastern Sicily from 1994 to 2001 and estimated coda- Q, intrinsic and scattering attenuation. We used the single scattering assumption to fit the amplitude envelopes of the coda at different frequency bands, obtaining a Qc varying with frequency as generally observed in tectonically active areas. Lapse time dependence has been also studied for the area, with the coda waves analyzed at window lengths ranging from 15 to 50 s, provided the coda duration permitted it. We found that Q0 ( Qc at 1 Hz) increases with lapse time and we interpreted this as due to increasing Qc with depth. Conversely, the frequency dependence coefficient n is mostly stationary at all the lapse time window lengths. Finally, using the independent estimates of Qc and the total Q ( QT) previously obtained for the area by other authors from direct S-waves of the same data set, we separated the intrinsic ( ) from the scattering ( ) attenuation factor. The results suggest that in Southeastern Sicily intrinsic dissipation plays a predominant role with respect to scattering phenomena.
    Description: Published
    Description: 55-66
    Description: partially_open
    Keywords: Coda waves ; Intrinsic attenuation ; Scattering ; Frequency dependence and Southeastern Sicily ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 46
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    Genesis of chlorine and sulphur in fumarolic emissions at Vulcano Island (Italy) : assessment of pH and redox conditions in the hydrothermal system (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Chlorine- and sulphur-bearing compounds in fumarole discharges of the La Fossa crater at Vulcano Island (Italy) can be modelled by a mixing process between magmatic gases and vapour from a boiling hydrothermal system. This allows estimating the compounds in both endmembers. Magma degassing cannot explain the time variation of sulphur and HCl concentrations in the deep endmember, which are more probably linked to reactions of solid phases at depth, before mixing with the hydrothermal vapours. Based on the P^T conditions and speciation of the boiling hydrothermal system below La Fossa, the HCl and Stot contents in the hydrothermal vapours were used to compute the redox conditions and pH of the aqueous solution. The results suggest that the haematite magnetite buffer controls the hydrothermal fO2 values, while the pH has increased since the end of the 1970s. The main processes affecting pH values may be linked to Na^Ca exchanges between evolved seawater, feeding the boiling hydrothermal system, and local rocks. While Na is removed from water, calcium enters the solution, undergoes hydrolysis and produces HCl,lowering the pH of the water. The increasing water^rock ratio within the hydrothermal system lowers the Ca availability, so the aqueous solution becomes less acidic. Seawater flowing towards the boiling hydrothermal brine dissolves a large quantity of pyrite along its path. In the boiling hydrothermal system, dissolved sulphur precipitates as pyrite and anhydrite, and becomes partitioned in vapour phase as H2S and SO2. These results are in agreement with the paragenesis of hydrothermal alteration minerals recovered in drilled wells at Vulcano and are also in agreement with the isotopic composition of sulphur emitted by the crater fumaroles.
    Description: Published
    Description: 137-150
    Description: partially_open
    Keywords: chlorine ; sulphur ; hydrothermal system ; genetic processes ; Vulcano Island ; 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::04.08.04. Thermodynamics ; 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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  • 47
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    Groundwater radon measurements in the Mt. Etna area (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Radon levels were measured in 119 groundwater samples collected throughout the active volcanic area of Mt. Etna by means of a portable Lucas-type scintillation chamber. The measured activity values range from 1.8 to 52.7 Bq l 1. About 40% of the samples exceed the maximum contaminant level of 11 Bq l 1 proposed by the USEPA in 1991. The highest radon levels are measured in the eastern sector of the volcano, which is the seismically most active zone of the volcano. On the contrary the south-western sector, which is both seismically active and a site of intense magmatic degassing, display lower radon levels. This is probably due to the formation of a free gas phase (oversaturation of CO2) that strips the radon from the water. Comparison of the data gathered at Mt. Etna with those of other areas indicates that 222Rn activity in groundwater is positively correlated with both the content of parent elements in the aquifer rocks and the temperature of the geothermal systems that interacts with the sampled aquifers.
    Description: Published
    Description: 187–201
    Description: partially_open
    Keywords: Groundwater ; Radon ; Mount Etna ; Active volcanic areas ; 03. Hydrosphere::03.02. Hydrology::03.02.03. Groundwater processes ; 03. Hydrosphere::03.02. Hydrology::03.02.06. Water resources ; 03. Hydrosphere::03.04. Chemical and biological::03.04.03. Chemistry of waters ; 03. Hydrosphere::03.04. Chemical and biological::03.04.07. Radioactivity and isotopes ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.08. Risk::05.08.01. Environmental risk
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  • 48
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    Contrasting triggering mechanisms of the 2001 and 2002–2003 eruptions of Mount Etna (Italy) (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Mount Etna produced two significant eruptions in 2001 and 2002–2003, which we have analysed using geological, seismic and deformation data. These eruptions showed some similarities, such as the activating of two magmatic plumbing systems (central–lateral and eccentric), but they differed in their triggering mechanisms. While the 2001 eruption was largely the result of the emplacement of a N–S eccentric dike (independent from the central conduits) consistent with E–W regional extension, the 2002–2003 eruption occurred in response to a major flank slip on the eastern and southeastern sides of the volcano. This is demonstrated by the spatial and temporal distribution of seismicity and deformation preceding and accompanying the two eruptions. During the months prior to the 2001 eruption, most epicenters were concentrated on the southern flank, at depths of 5–15 km below sea level. During the 4 days before the eruption, earthquake hypocenters migrated to shallower levels (from 5 km bsl. upward) indicating the emplacement of the eccentric dike. This is confirmed by the patterns of ground fracturing observed in the field and deformation documented by electronic distance measurements (EDM). In contrast, the months before the 2002–2003 eruption were characterised by shallower seismicity, mainly concentrated along the active faults bordering the slipping flank sector. Flank slip accelerated in September 2002 and a second, more vigorous acceleration of flank slip occurred on 26–27 October 2002, accompanying the opening of eruptive vents. The very short (2 h) seismic crisis preceding the onset of eruptive activity stands in neat contrast with the 4 days of intense seismicity before the 2001 eruption. Subsequently, flank slip-deformation extended all over the eastern and southeastern flanks of the volcano, causing serious damage in this sector. The events of 2001–2003 can be seen as a continuous chain of intimately interacting processes including regional tectonics, magma accumulation and eruption, and flank instability. In this scenario the 2001 eruption led to increased flank instability that subsequently accelerated and culminated with the massive flank slip, which in turn facilitated the 2002–2003 eruption. This sequence of events points to a long-term feedback mechanism between magmatism and flank instability at Etna.
    Description: Published
    Description: 235-255
    Description: partially_open
    Keywords: eruption triggering ; central–lateral vs. eccentric eruptions ; flank instability and slip ; volcano-tectonics ; Mt. Etna ; instrumental monitoring ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 49
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    Fluid circulation at Stromboli volcano (Aeolian Islands, Italy) from self-potential and CO2 surveys (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: This work addresses the study of fluid circulation of the Stromboli island using a dense coverage of self-potential (SP) and soil CO2 data. A marked difference exists between the northern flank and the other flanks of the island. The northern flank exhibits (1) a typical negative SP/altitude gradient not observed on the other flanks, and (2) higher levels of CO2. The general SP pattern suggests that the northern flank is composed of porous layers through which vadose water flows down to a basal water table, in contrast to the other flanks where impermeable layers impede the vertical flow of vadose water. In the Sciara del Fuoco and Rina Grande-Le Schicciole landslide complexes, breccias of shallow gliding planes may constitute such impermeable layers whereas elsewhere, poorly permeable, fine-grained pyroclastites or altered lava flows may be present. This general model of the flanks also explains the main CO2 patterns: concentration of CO2 at the surface is high on the porous north flank and lower on the other flanks where impermeable layers can block the upward CO2 flux. The active upper part of the island is underlain by a well-defined hydrothermal system bounded by short-wavelength negative SP anomalies and high peaks of CO2. These boundaries coincide with faults limiting ancient collapses of calderas, craters and flank landslides. The hydrothermal system is not homogeneous but composed of three main subsystems and of a fourth minor one and is not centered on the active craters. The latter are located near its border. This divergence between the location of the active craters and the extent of the hydrothermal system suggests that the internal heat sources may not be limited to sources below the active craters. If the heat source strictly corresponds to intrusions at depth around the active conduits, the geometry of the hydrothermal subsystems must be strongly controlled by heterogeneities within the edifice such as craters, caldera walls or gliding planes of flank collapse, as suggested by the correspondence between SP^CO2 anomalies and structural limits. The inner zone of the hydrothermal subsystems is characterized by positive SP anomalies, indicating upward movements of fluids, and by very low values of CO2 emanation. This pattern suggests that the hydrothermal zone becomes self-sealed at depth, thus creating a barrier to the CO2 flux. In this hypothesis, the observed hydrothermal system is a shallow one and it involves mostly convection of infiltrated meteoric water above the sealed zone. Finally, on the base of CO2 degassing measurements, we present evidence for the presence of two regional faults, oriented N41‡ and N64‡, and decoupled from the volcanic structures.
    Description: Published
    Description: 1^18
    Description: partially_open
    Keywords: Stromboli ; hydrothermal system ; self-potential ; soil gas ; carbon dioxide ; Aeolian islands ; 03. Hydrosphere::03.02. Hydrology::03.02.02. Hydrological processes: interaction, transport, dynamics ; 03. Hydrosphere::03.04. Chemical and biological::03.04.06. Hydrothermal systems ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 50
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    A multidisciplinary approach to detect active pathways for magma migration and eruption at Mt. Etna (Sicily, Italy) before the 2001 and 2002-03 eruptions (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Two strong flank eruptions occurred in July–August 2001 and from late October 2002 to late January 2003 at Mt. Etna volcano. The two eruptions mainly involved the upper southern flank of the volcano, a particularly active area during the last 30 years, damaging several tourist facilities and threatening some villages. The composite eruptive activity on the upper southern flank of Mt. Etna during 2001–2003 has confirmed “a posteriori” the results of a multidisciplinary study, started well before its occurrence by combining geological, seismic and geochemical data gathered in this part of the volcano. We were able, in fact, to highlight fractured zones likely to be re-activated in the near future in this area, where the largest majority of eruptive fissures in the recent past opened along N120° to N180° ranging directions. The spatial distribution of earthquake epicentres during the period June 30th 2000–June 30th 2001 showed the greatest frequency in a sector compatible with both the direction of the main fissures of the pre-2001 period and that of the 2001 and 2002 lateral eruptions. Soil CO2 and soil temperature surveys carried out in the studied area during the last 3 years have revealed anomalous release of magmatic fluids (mainly CO2 and water vapour) along some NNW–SSE-trending volcano-tectonic structures of the area even during inter-eruptive periods, indicating persistent convective hydrothermal systems at shallow depth connected with the main feeder conduits of Etna. The temporal changes in both seismic and geochemical data from June 30th, 2000 to June 30th, 2001 were compared with the evolution of volcanic activity. The comparison allowed to recognize at least two sequences of anomalous signals (August to December 2000 and April to June 2001), likely related to episodes of step-like magma ascent towards the surface, as indicated by the following eruptive episodes. The N120° to N180° structural directions are in accord with one of the main structural lines affecting eastern Sicily; they would be important pathways for magma uprise to the surface that will keep on feeding the eruptive activity of Etna in the near future. This study also pointed out the high instability of the southern slope of Etna, a sector where the potential hazard by lava flow invasion will remain high also in the near future.
    Description: Published
    Description: 20
    Description: partially_open
    Keywords: Mt. Etna ; fault detection ; soil gas ; historical eruptive fissures ; eruptive activity ; local seismicity ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
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  • 51
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    Fluid circulation and structural discontinuities inside Misti volcano (Peru) inferred from self-potential measurements (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: One of the seven potentially active andesite stratovolcanoes in southern Peru, Misti (5822 m), located 17 km northeast and 3.5 km above Arequipa, represents a major threat to the population (f900,000 inhabitants). Our recent geophysical and geochemical research comprises an extensive self-potential (SP) data set, an audioâ magnetotelluric (AMT) profile across the volcano and CO2 concentrations in the soil along a radial profile. The SP survey is the first of its kind in providing a complete mapping of a large andesitic stratovolcano 20 km in diameter. The SP mapping enables us to analyze the SP signature associated with a subduction-related active volcano. The general SP pattern of Misti is similar to that of most volcanoes with a hydrogeologic zone in the lower flanks and a hydrothermal zone in the upper central area. A quasi-systematic relationship exists between SP and elevation. Zones with constant SP/altitude gradients (Ce) are observed in both hydrogeologic (negative Ce) and hydrothermal (positive Ce) zones. Transition zones between the different Ce zones, which form a concentric pattern around the summit, have been interpreted in terms of lateral heterogeneities in the lithology. The highest amplitudes of SP anomalies seem to coincide with highly resistive zones. The hydrothermal system 6 km in diameter, which extends over an area much larger than the summit caldera, may be constrained by an older, concealed collapse caldera. A sealed zone has apparently developed through alteration in the hydrothermal system, blocking the migration of CO2 upward. Significant CO2 emanations are thus observed on the lower flanks but are absent above the hydrothermal zone.
    Description: - Institut de Recherche pour le Developpement (IRD) - Instituto Geofısico del Peru´ (IGP)
    Description: Published
    Description: 343-360
    Description: partially_open
    Keywords: Misti volcano ; self-potential ; audioâ magnetotelluric ; electrical resistivity ; structural discontinuity ; hydrothermal system ; Peru ; 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::04.08.07. Instruments and techniques
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  • 52
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    A new collector for sampling volcanic aerosols (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: A new apparatus, Venturi Effect System (VES), designed for sampling volcanic plumes is described and tested at Vulcano (Italy). This device, together with purified basic NH4OH solutions, supplies optimal conditions to obtain reliable Stotal/Cl/F ratios and enrichment factors for metallic trace elements (MTE). Good concordance for acid gas ratios and metal enrichment factors in both the gas phase and the related plume allows the procedure to be validated. The VES appears in Vulcano conditions as a simple, robust and easily portable apparatus that allows reliable collection of both acid gases and MTE within a single sample and the analysis with current chemical methods (High Pressure Liquid Chromatography, Inductively Coupled Plasma-Mass Spectrometry. This apparatus may be suitable for more difficult volcanoes where only the plume can be sampled.
    Description: Published
    Description: 95-103
    Description: partially_open
    Keywords: volcanic plume ; acid gases ; metallic trace elements ; sampling ; monitoring ; 03. Hydrosphere::03.02. Hydrology::03.02.02. Hydrological processes: interaction, transport, dynamics ; 03. Hydrosphere::03.02. Hydrology::03.02.03. Groundwater processes
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    Probabilistic source location of explosion quakes at Stromboli volcano estimated with double array data (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Data from two dense arrays of short-period seismometers are used to retrieve source locations of the explosion quakes at Stromboli volcano. Slowness vectors stimated at both arrays with the zero-lag cross-correlation technique constitute the experimental data set. A probabilistic approach based on a grid search spanning the volcano interior is used to calculate the probability of the source location. Results depict a shallow source, located beneath the crater area, at depths not greater than 500 m below the surface. Results are slightly different from, but comparable to, those obtained in a companion experiment carried out in the same time period using a broad-band seismometer network, which show a source shifted some hundreds of meters northwest of the crater area. The method is revealed to be effective and useful for future studies having the purpose of real-time tracking of the explosion quakes and tremor.
    Description: Published
    Description: 123-142
    Description: partially_open
    Keywords: Stromboli ; Array ; Explosion quake ; Source location ; 04. Solid Earth::04.02. Exploration geophysics::04.02.06. Seismic methods ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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    Trace metal modeling of groundwater–gas–rock interactions in a volcanic aquifer: Mount Vesuvius, Southern Italy (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: We report a detailed study of trace metals in groundwaters from the Somma-Vesuvius volcanic complex and present a model of the chemical processes that control the fate of these components during gas–water–rock interactions. Trace metal concentrations in Vesuvian groundwaters range from 0.01 to 0.1 Ag/l for ultra-trace elements (Sb, Cs, Co, Cd, and Pb) up to 0.1–10 mg/l for minor elements (Fe and Sr), leading to water–rock ratios from ~0.5 to 10 9 when normalized to trace element concentrations in the host rocks. Our results indicate non-isochemical dissolution of local volcanic rocks by groundwaters,during which mobile trace elements (As, Se, Mo, V, Li) are enriched and elements such as Al, Pb, Co, and Mn are depleted in the aqueous phase compared to the pristine composition of unleached rocks. Speciation computation and mineral–solution equilibria provide insights into the processes controlling the abundance and mobility of both major and trace elements in the fluids and allow quantitative modeling of gas–water–rock interactions. This latter was done using a forward reaction path model based on the principle of irreversible reactions involving minerals and aqueous solutions (Helgeson, H.C., 1968. Evaluation of irreversible reactions in geochemical processes involving minerals and aqueous solutions: I. Thermodynamic relations. Geochim. Cosmochim. Acta, 32, 853–877), and incorporating transition-state theory to account for rates of mineral dissolution reactions (Aagaard, P., Helgeson, H.C., 1982. Thermodynamic and kinetic constraints on reaction rates among minerals and aqueous solutions, 1. Theoretical considerations. Amer. J. Sci., 282, 237–285). The EQ3NR/6 software package (Wolery, T.J.,1994. EQ3NR, Letter report: EQ3/6 version 8.0. Differences from version 7. UCRL_ID_129749, Lawrence Livermore National Laboratory, Livermore, California) was used to simulate the reaction paths and the aqueous concentrations of trace elements with increasing extent of rock weathering. Fairly good matching between the modeled and analytical groundwater compositions supports the validity of our approach and provides reliable information on the main sources and sinks of trace metals during gas–water–rock interactions in the volcanic aquifer of Vesuvius.
    Description: Published
    Description: 289– 311
    Description: partially_open
    Keywords: trace elements ; Vesuvius ; EQ3/6 ; kinetics ; weathering ; 04. Solid Earth::04.08. Volcanology::04.08.04. Thermodynamics ; 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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    A model for the numerical simulation of tephra fall deposits (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: A simple semianalytical model to simulate ash dispersion and deposition produced by sustained Plinian and sub-Plinian eruption columns based on the 2D advection-dispersion equation was applied. The eruption column acts as a vertical line source with a given mass distribution and neglects the complex dynamics within the eruption column. Thus, the use of the model is limited to areas far from the vent where the dynamics of the eruption column play a minor role. Vertical wind and diffusion components are considered negligible with respect to the horizontal ones. The dispersion and deposition of particles in the model is only governed by gravitational settling, horizontal eddy diffusion, and wind advection.The model accounts for different types and size classes of a user-defined number of particle classes and changing settling velocity with altitude. In as much as wind profiles are considered constant on the entire domain, the model validity is limited to medium-range distances (about 30–200 km away from the source). The model was used to reconstruct the tephra fall deposit from the documented Plinian eruption of Mt. Vesuvius, Italy, in 79 A.D. In this case, the model was able to broadly reproduce the characteristic medium-range tephra deposit. The results support the validity of the model, which has the advantage of being simple and fast to compute. It has the potential to serve as a simple tool for predicting the distribution of ash fall of hypothetical or real eruptions of a given magnitude and a given wind profile. Using a statistical set of frequent wind profiles, it also was used to construct air fall hazard maps of the most likely affected areas around active volcanoes where a large eruption is expected to occur.
    Description: Published
    Description: 273-294
    Description: partially_open
    Keywords: Ash fall ; Settling velocity ; Computer model ; Vesuvius 79 A.D. ; 05. General::05.01. Computational geophysics::05.01.05. Algorithms and implementation
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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    Scaling characteristics of local geomagnetic field and seismicity at Etna volcano and their dynamics in relation to the eruptive activity (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The evolution of scaling characteristics of the local geomagnetic field and of the seismicity at Etna volcano is studied in relation to the strong eruptive activity occurred here from 2000 to 2002. Scaling laws are found in the hourly time variability of magnetic data and in the seismicity pattern. The scaling exponents suggest the presence of persistent temporal fluctuations. Clear links between the dynamics of the measured data and the eruptive volcanic episodes are revealed. Fractal dimensions of seismicity seem to be always correlated to the beginning of main eruptive events, while strong alterations of the dynamics of the local magnetic field take place only when the eruptive fractures opened very close to the magnetic sites.
    Description: Published
    Description: 96-106
    Description: partially_open
    Keywords: scaling characteristics ; volcanic eruptions ; geomagnetic field ; seismic activity ; Mt. Etna ; 04. Solid Earth::04.05. Geomagnetism::04.05.02. Geomagnetic field variations and reversals ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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    A computer model for volcanic ashfallout and assessment of subsequent hazard (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: HAZMAP is a FORTRAN code for the solution of the equations of diffusion, transport and sedimentation of small particles, in order to model the dispersion of ash generated by a convective column. The model was developed simplifying the advection–diffusion sedimentation equation for volcanic ash transport in the atmosphere from three to two dimensions and using a semi-analytical computational method to greatly reduce the required computer time and memory. HAZMAP can be used either to simulate the mass distribution of the deposit if a wind profile is given (‘deposit mode’), or to define the probability of a given accumulation of mass on the ground if a statistical set of wind profiles is provided (‘‘probability mode’’). The model needs the definition of the physical system (spatial distribution of the point sources, total erupted mass, settling velocity distribution, wind velocity profile, atmospheric turbulent diffusion coefficients), and of a computational grid. The output values of mass accumulation on the ground or the probability of mass accumulation are computed on a regular grid, suitable for further analysis.
    Description: Published
    Description: 837-845
    Description: partially_open
    Keywords: Ashfall ; Fortran code ; Volcanology ; Volcanic hazard ; Semi-analytical model ; 05. General::05.01. Computational geophysics::05.01.05. Algorithms and implementation
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    Dissolved helium isotope ratios in ground-waters: a new technique based on gas–water re-equilibration and its application to Stromboli volcanic system (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Here, a new technique for the determination of dissolved He isotope ratios in ground-waters is presented. This method is based on the extraction and subsequent equilibrium of dissolved gases in an added ‘‘host’’ gas phase. Ultra pure N2 is placed in glass flasks (250 cc), containing water samples, that were hermetically sealed after their collection. After shaking in an ultrasonic bath for 10 min, an aliquot of the separated gas phase was removed from the flask for MS analysis. 3He/4He ratios are measured by using a modified double collector mass spectrometer (VG 5400-TFT). Helium and Ne concentrations are calculated by comparing the partial pressures of masses 4 and 20 of the samples with those of the air-standard measured by a quadrupole mass spectrometer (QMS;VG Quartz). Using He and Ne equilibrium partitioning coefficients, it is possible to calculate the amount of gas originally dissolved in the water. The technique was tested on both air-saturated waters (ASW) and thermal waters from Stromboli (Aeolian Islands, South Italy), the results of which confirmed good reproducibility (ffi5%) and accuracy (ffi3%) of the data. The method was then applied to three thermal water samples collected from the same volcanic area and the results compared with those of a fumarolic and a soil gas. The isotope ratios for dissolved He gave values of 4.06–4.23 Ra, which are significantly higher than those previously reported in the literature (3.0, 3.5 and 2.9 Ra) and that measured at the fumarole (3.09 Ra), suggesting a newer and higher isotopic signature for the volcanic system. The proposed method appears to be a useful tool in the determination of 3He/4He ratios in ground-water systems, especially when free gases are not available or are dangerous to collect.
    Description: Published
    Description: 665–673
    Description: partially_open
    Keywords: dissolved helium isotopes ; gas water interaction ; 03. Hydrosphere::03.02. Hydrology::03.02.03. Groundwater processes ; 03. Hydrosphere::03.04. Chemical and biological::03.04.06. Hydrothermal systems ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases
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    Nested zones of instability in the Mount Etna volcanic edifice, Italy (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Large-scale flank instability on Mount Etna is associated with a distinct set of faults radiating generally from the summit area and restricted to the volcanic edifice itself. New observations and mapping of very recent and continuing deformation along these faults and related structures have been analysed in combination with published information, including recent seismic and eruption data, enabling the faults to be placed in three groups. Two of these, the Pernicana fault system (PFS) and the Ragalna fault system (RFS) bound, respectively, the northern and south-western margins of instability. Their activity responds to cycles of magma pressure associated with flank eruptions, together with subsequent deflation as gravity dominates. These cycles may operate at different depths, with the RFS bordering deep-seated instability. Their positions appear governed by the contact, in the substrate of the volcano, between relatively weak early Quaternary clays and stronger rocks of the Apennine–Maghrebian Chain that rise towards the north and west in the subsurface, buttressing the edifice in these directions. The unstable mass to the un-buttressed south and east is thus defined by its weak substrate and displays structures similar to those produced in model experiments. The third fault group, the Mascaluci–-Trecastagni fault system, borders a rather faster-moving zone of instability in the eastern part of the large unstable mass, outlining one element in a nested pattern in map view. Low-angle detachments below the unstable zones are thought to occur at different levels above a deep and laterally extensive detachment associated with the RFS, producing a nested pattern in section as well. This is illustrated by the PFS where the long-recognised western half of the fault borders a fast moving zone of instability riding above a detachment that daylights as a thrusted deformation front marked by recurring landsliding at an approximate mid-slope position on the volcano. Downslope, the newly recognised eastern extension of the PFS, exhibiting slip-rates an-order-of-magnitude lower than the western segment, is thought to border a deeper slow-moving detachment that daylights offshore. Windows of deformed sub-Etnean clays at anomalously high altitudes may indicate where similar detachments, no longer mechanically favoured and now inactive, have daylighted. As a result, the edifice can be considered, overall, as consisting of multiple unstable areas, nested in plan view and with basal detachments occurring at different levels in section. This model of edifice behaviour is regarded as an evolving one, with detachments waxing and waning in their activity as flank movement progresses.
    Description: Published
    Description: 137-153
    Description: partially_open
    Keywords: Mount Etna ; instability; flank faults ; volcano collapse models ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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    Natural and anthropogenic factors affecting groundwater quality of an active volcano (Mt. Etna, Italy) (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: New geochemical data on dissolved major and minor constituents in 276 groundwater samples from Etna aquifers reveal the main processes responsible for their geochemical evolution and mineralisation. This topic is of particular interest in the light of the progressive depletion of water resources and groundwater quality in the area. Multivariate statistical analysis reveal 3 sources of solutes: (a) the leaching of the host basalt, driven by the dissolution of magmaderived CO2; (b) mixing processes with saline brines rising from the sedimentary basement below Etna; (c) contamination from agricultural and urban wastewaters. The last process, highlighted by increased concentrations of SO4,NO3, Ca, F and PO4, is more pronounced on the lower slopes of the volcanic edifice, associated with areas of high population and intensive agriculture. However, this study demonstrates that natural processes (a) and (b) are also very effective in producing highly mineralised waters, which in turn results in many constituents (B, V, Mg) exceeding maximum admissible concentrations for drinking water.
    Description: Published
    Description: 863–882
    Description: partially_open
    Keywords: Hydrogeochemistry ; water quality ; Mt. Etna ; 03. Hydrosphere::03.02. Hydrology::03.02.03. Groundwater processes ; 03. Hydrosphere::03.02. Hydrology::03.02.04. Measurements and monitoring ; 03. Hydrosphere::03.02. Hydrology::03.02.06. Water resources ; 03. Hydrosphere::03.04. Chemical and biological::03.04.03. Chemistry of waters
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    Isotopic, chemical and dissolved gas constraints on spring water from Popocatepetl volcano (Mexico): evidence of gas–water interaction between magmatic component and shallow fluids (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Geochemical research was carried out on cold and hot springs at Popocatepetl (Popo) volcano (Mexico) in 1999 to identify a possible relationship with magmatic activity. The chemical and isotopic composition of the fluids is compatible with strong gas–water interaction between deep and shallow fluids. In fact, the isotopic composition of He and dissolved carbon species is consistent with a magmatic origin. The presence of a geothermal system having a temperature of 80–1008 C was estimated on the basis of liquid geothermometers. A large amount of dissolved CO2 in the springs was also detected and associated with high CO2 degassing.
    Description: Published
    Description: 91– 108
    Description: partially_open
    Keywords: Popocatepetl volcano ; helium isotope composition ; carbon isotope composition ; dissolved gases ; gas–water interaction ; 03. Hydrosphere::03.02. Hydrology::03.02.03. Groundwater processes ; 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::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases
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    Magma dynamics in the shallow plumbing system of Mt. Etna as recorded by compositional variations in volcanics of recent summit activity (1995–1999) (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: We describe the reactivation and the successive evolution of the shallow plumbing system of Mt. Etna between the end of the largest flank eruption of the last three centuries (1991–1993) and the subterminal eruption from South-East Crater (SEC), which occurred between February and mid-November 1999. Our analysis is based on observations of the volcanic activity and petrological studies of the erupted volcanics. Bulk rock, mineral and glass compositions have been determined for more than 80 samples erupted from the four summit craters between October 1995 and February 1999. These data allow us to recognise significant compositional variations among the products of different craters. In particular, volcanics produced between 1995 and 1999 by Bocca Nuova (BN), Voragine (VOR) and North-East Crater (NEC) show limited compositional variations and are similar to those observed during recent eruptions (e.g., 1991–93). More primitive magmas have been produced during the more vigorous fire fountains episodes. On the contrary, the South-East Crater produced slightly more differentiated volcanics than those of the other summit craters following its reactivation (November 1996) until the end of 1998. Whole rock compositions of products from this crater show low CaO/Al2O3, whereas interstitial glasses have lower MgO and higher alkali contents than those from the other craters. However, since the beginning of 1999, and just before the start of the subterminal eruption from SEC, the volcanics erupted from this crater progressively changed in composition, becoming similar to those of the other craters. This trend indicates that within the conduits of the summit craters, distinct thermal and fluid-dynamical regimes can evolve, controlling the cooling and crystallisation of Etna magmas.
    Description: Published
    Description: 55-71
    Description: partially_open
    Keywords: Mount Etna ; crystal fractionation ; petrologic monitoring and magmatic process ; 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::04.08.05. Volcanic rocks
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    Genesis of fumarolic emissions as inferred by isotope mass balances: CO2 and water at Vulcano Island, Italy (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: We have developed a quantitative model of CO2 and H2O isotopic mixing between magmatic and hydrothermal gases for the fumarolic emissions of the La Fossa crater (Vulcano Island, Italy). On the basis of isotope balance equations, the model takes into account the isotope equilibrium between H2O and CO2 and extends the recent model of chemical and energy two-end-member mixing by Nuccio et al. (1999). As a result,the H2O and CO2 content and the dD, d18O, and d13C isotope compositions for both magmatic and hydrothermal end-members have been assessed. Low contributions of meteoric steam, added at a shallow depth, have been also recognized and quantified in the fumaroles throughout the period from 1988 to 1998. Nonequilibrium oxygen isotope exchange also seems to be occurring between ascending gases and wall rocks along some fumarolic conduits. The d13CCO2 of the magmatic gases varies around -3 to 1‰ vs. Peedee belemnite (PDB), following a perfect synchronism with the variations of the CO2 concentration in the magmatic gases. This suggests a process of isotope fractionation because of vapor exsolution caused by magma depressurization. The hydrogen isotopes in the magmatic gases (-1 to -35‰ vs. standard mean ocean water [SMOW]), as well as the above d13CCO2 value, are coherent with a convergent tectonic setting of magma generation, where the local mantle is widely contaminated by fluids released from the subducted slab. Magma contamination in the crust probably amplifies this effect. The computed isotope composition of carbon and hydrogen in the hydrothermal vapors has been used to calculate the dD and d13C of the entire hydrothermal system, including mixed H2O-CO2 vapor, liquid water, and dissolved carbon. We have computed values of about 10‰ vs. SMOW for water and -2 to -6.5‰ vs. PDB for CO2. On these grounds, we think that Mediterranean marine water (dDH2O 10‰) feeds the hydrothermal system. It infiltrates at depth throughout the local rocks, reaching oxygen isotope equilibrium at high temperatures. Interaction processes between magmatic gases and the evolving seawater also seem to occur, causing the dissolution of isotopically fractionated aqueous CO2 and providing the source for hydrothermal carbon. These results have important implications concerning fluid circulation beneath Vulcano and address the more convenient routine of geochemical surveillance.
    Description: Published
    Description: 759–772
    Description: partially_open
    Keywords: isotope geochemistry ; volcanic gases ; mixing modeling ; 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::04.08.03. Magmas ; 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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    Influence of volcanic activity on spring water chemistry at Popocatepetl Volcano, Mexico (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The results of the 7 years (1994-2000) of monthly monitoring of spring water before and during eruptions show response to volcanic activity. Low salinity and temperature characterize most of the springs, which are located on the flanks of Popocatepetl Volcano. The pH ranges from 5.8 to 7.8 and temperature from 3 to 36 jC. Oxygen and hydrogen isotopic data show that the water is of meteoric origin, but SO4 2 , Cl , F , HCO3 , B, and SO4 2- /Cl- variations precede main eruptive activity, which is considered linked to influx of magmatic gases and acid fluids that react with sublimates and host rock and mix with the large water system. Na +, Ca2 + , SiO2 and Mg2 + concentrations in the water also increased before eruptive activity. The computed partial pressure of CO2 in equilibrium with spring waters shows values higher than air-saturated water (ASW), with the highest values up to 0.73 bar of pCO2. Boron is detected in the water only preceding the larger eruptions. When present, boron concentration is normally under health standard limits, but in two cases the concentration was slightly above. Other components are within health standard limits, except for F- in one spring.
    Description: Published
    Description: 207– 229
    Description: partially_open
    Keywords: Volcano monitoring ; Spring water chemistry ; Popocatepetl ; Mexico ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 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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    A multidisciplinary approach to the evaluation of the mechanism that triggered the Cerda landslide (Sicily, Italy) (2005)
    Elsevier
    Details
    Publication Date: 2020-03-02
    Description: The present paper describes a multidisciplinary approach to the evaluation of a seismically triggered landslide that occurred in the Cerda area (Italy) on September 6, 2002, about 1 h after an earthquake took place in the south Tyrrhenian Sea. The study was focused on an analysis of the role of the seismic input in triggering the landslide, in view of the evidence that no other mass movement was recorded in the adjacent areas despite geological and geomorphological spatial homogeneity. The studied area is located on a slope of the western flank of the Fiume Imera Settentrionale (Northern Sicily), which is made up of clayey–arenitic rocks. The slope inclines gently but is not uniform due to fluvial, gravitative, and rainwash processes. Field data dealing with global positioning system (GPS), geology, geomorphology, geophysics (vertical electrical sounding, or VES), and geochemistry (soil gas fluxes and composition) were acquired and analysed in order to investigate the cause–effect relationships between the earthquake and the mass movement. The GPS survey allowed us to map the ground failures that have also been classified on the basis of their kinematical meaning (i.e., compressive, distensive, or transcurrent structures). The geological analysis revealed outcropping rocks and tectonic structures. The geomorphologic survey highlighted the presence of preexisting landslide bodies. The geophysical survey detected a buried surface located at a depth of about 100 m . Finally, the geochemical survey showed that the gas released from the displaced mass came from a shallow depth and was not related to any active fault system. The abovementioned information allowed us to interpret the landslide event as a partial reactivation of a preexisting landslide body that was triggered by the earthquake.
    Description: Ministero dell’Istruzione, dell’Universita` e della Ricerca (MIUR), Cofinanziamento Progetti di Ricerca di Rilevante Interesse Nazionale (COFIN PRIN) 2002 Project "Valutazione dell’Erosione del Suolo in Ambiente Mediterraneo"
    Description: Published
    Description: 101–116
    Description: partially_open
    Keywords: Landslide ; Earthquake ; Geochemistry ; Geophysics ; GPS ; Triggering mechanism ; 04. Solid Earth::04.04. Geology::04.04.03. Geomorphology
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    Tantalum : a case study on sustainable resource management (2005)
    Essen : Verl. Glückauf | Wuppertal : Wuppertal Institut für Klima, Umwelt, Energie
    Details
    Publication Date: 2016-08-23
    Keywords: ddc:600
    Repository Name: Wuppertal Institut für Klima, Umwelt, Energie
    Language: English
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    Sustainability of the Benguela: ex Africa semper aliquid novi (2005)
    Elsevier
    Details
    Publication Date: 2021-05-19
    Description: The Benguela Current ecosystem is situated along the coast of south western Africa, stretching from east of the Cape of Good Hope, in the south, northwards into Angola waters and encompassing the full extent of Namibia’s marine environment. It is one of the four major coastal upwelling ecosystems of the world which lie at the eastern boundaries of the oceans. Like the Humboldt, California and Canary systems, the Benguela is an important centre of marine biodiversity and marine food production. Its distinctive bathymetry, hydrography, chemistry and trophodynamics combine to make it one of the most productive ocean areas in the world, with a mean annual primary productivity of 1.25 kilograms of carbon per square metre per year—about six times higher than the North Sea ecosystem. This high level of primary productivity of the Benguela supports an important global reservoir of biodiversity and biomass of zooplankton, fish, sea birds and marine mammals, while near-shore and off-shore sediments hold rich deposits of precious minerals (particularly diamonds), as well as oil and gas reserves.
    Description: Published
    Keywords: Ecosystems ; Sustainability
    Repository Name: AquaDocs
    Type: Book Section , Non-Refereed
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  • 68
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    Physiological responses of two ecologically important Kenyan mangrove crabs exposed to altered salinity regimes (2005)
    Elsevier
    Details
    Publication Date: 2021-05-19
    Description: The potential long-term effects of altered salinity regimes on the bioenergetics of two ecologically important Kenyan mangrove crabs, Neosarmatium meinerti de Man, 1887 and Neosarmatium smithi H. Milne Edwards, 1853 were investigated in light of recent findings suggesting that groundwater redirection may alter salinity regimes in Kenyan mangroves. Although changes in groundwater may cause only small increases in salinities, these changes would be chronic and may impact crab populations already living above their optimal salinity. To assess potential impacts, fundamental physiological processes and hemolymph components were measured on animals acclimated to 16‰, 32‰, 48‰ and 65‰ for 4 weeks in a field laboratory. For comparative purposes, crabs were also sampled in the field. N. smithi survived poorly in all salinities except the control (32‰). Although high mortality in N. smithi did not allow for reliable estimations of an energy budget, mortality and osmoregulatory capacity shows that this species can osmoregulate for a limited time in elevated salinities (±1 week), but cannot withstand long-term hypersaline conditions. In contrast, N. meinerti survived well and was able to osmoregulate for 1 month in all salinity treatments. Nevertheless, their energy budget, was significantly reduced (to below 0) in the 65‰ treatment. Overall, this study shows that these two congeneric species exhibit different long-term responses to variations in salinity. However, they are both negatively effected by hypersaline conditions, suggesting that long-term alteration of mangrove salinity regimes may be detrimental for these ecologically important mangrove crab populations.
    Description: EC, VLIR
    Description: Published
    Keywords: Ecophysiology ; Salinity tolerance ; Energy budget ; Osmoregulation ; Sesarmidae ; Crab fisheries
    Repository Name: AquaDocs
    Type: Journal Contribution , Refereed , Article
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  • 69
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    Temporal evolution of flow conditions in sustained magmatic explosive eruptions (2005)
    Elsevier
    Details
    Publication Date: 2022-02-21
    Description: The temporal evolution of fundamental flow conditions in the magma chamber plus conduit system–such as pressure, velocity, mass flow-rate, erupted mass, etc.–during sustained magmatic explosive eruptions was investigated. To this aim, simplified one-dimensional and isothermal models of magma chamber emptying and conduit flow were developed and coupled together. The chamber model assumed an homogeneous composition of magma and a vertical profile of water content. The chamber could have a cylindrical, elliptical or spherical rigid geometry. Inside the chamber, magma was assumed to be in hydrostatic equilibrium both before and during the eruption. Since the time-scale of pressure variations at the conduit inlet–of the order of hours–is much longer than the travel time of magma in the conduit–of the order of a few minutes–the flow in the conduit was assumed as at steady-state. The one dimensional mass and momentum balance equations were solved along a circular conduit with constant diameter assuming choked-flow conditions at the exit. Bubble nucleation was considered when the homogeneous flow pressure dropped below the nucleation pressure given the total water content and the solubility law. Above the nucleation level, bubbles and liquid magma were considered in mechanical equilibrium. The same equilibrium assumption was made above the fragmentation level between gas and pyroclasts. Due to the hydrostatic hypothesis, the integration of the density distribution in the chamber allowed to obtain the total mass in the chamber as a function of pressure at the chamber top and, through the conduit model, as a function of time. Simulation results pertaining to rhyolitic and basaltic magmas defined at the Volcanic Eruption Mechanism Modeling Workshops (Durham, NH, 2002; Nice, France, 2003) are presented. Important flow variables, such as pressure, density, velocity, shear stress in the chamber and conduit, are discussed as a function of time and magma chamber and conduit properties. Results indicate that vent variables react in different ways to the pressure variation of the chamber. Pressure, density and mass flow-rate show relative variations of the same order of magnitude as the conduit inlet pressure, whereas velocity is more constant in time. Sill-like chambers produce also significantly longer and more voluminous eruptions than dike-like chambers. Water content stratification in the chamber and the increase of chamber depth significantly reduce the eruption duration and volume. Maximum erupted mass fractions of about 0.2 are computed for small water-saturated and shallow chambers.
    Description: Published
    Description: 153-172
    Description: partially_open
    Keywords: Explosive eruptions ; Magma chamber discharge ; Conduit flow ; Temporal evolution ; Pressure evolution ; 05. General::05.01. Computational geophysics::05.01.05. Algorithms and implementation
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 70
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    Volcanogenic fluorine in rainwater around active degassing volcanoes: Mt. Etna and Stromboli Island, Italy (2005)
    Elsevier
    Details
    Publication Date: 2022-05-24
    Description: Many studies have assessed the strong influence of volcanic activity on the surrounding environment. This is particularly true for strong gas emitters such as Mt. Etna and Stromboli volcanoes. Among volcanic gases, fluorine compounds are potentially very harmful. Fluorine cycling through rainwater in the above volcanic areas was studied analysing more than 400 monthly bulk samples. Data indicate that only approximately 1% of fluorine emission through the plume is deposited on the two volcanic areas by meteoric precipitations. Although measured bulk rainwater fluorine fluxes are comparable to and sometimes higher than in heavily polluted areas, their influence on the surrounding vegetation is limited. Only annual crops, in fact, show some damage that could be an effect of fluorine deposition, indicating that long-living endemic plant species or varieties have developed some kind of resistance.
    Description: Published
    Description: 175–185
    Description: partially_open
    Keywords: Fluorine ; Rainwater chemistry ; Volcanic activity ; Mt. Etna ; Stromboli Island ; 01. Atmosphere::01.01. Atmosphere::01.01.07. Volcanic effects ; 03. Hydrosphere::03.03. Physical::03.03.01. Air/water/earth interactions ; 03. Hydrosphere::03.04. Chemical and biological::03.04.03. Chemistry of waters ; 03. Hydrosphere::03.04. Chemical and biological::03.04.05. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data ; 05. General::05.08. Risk::05.08.01. Environmental risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 71
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    Relating fault mechanics to fault zone structure (2005)
    Elsevier
    In:  Advances in Geophysics, ed.: Renata Dmowska, Warszawa, Elsevier, vol. 47, no. 7, pp. 65-111, pp. L21303, (ISBN: 0-12-018847-3)
    Details
    Publication Date: 2005
    Keywords: Fault zone ; Rock mechanics ; Friction ; Fracture ; Physical properties of rocks ; geometry
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    BIBLIOGRAPHY SEISMOLOGY
  • 72
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    Crustal deformation in the southcentral Alaska subduction zone (2005)
    Elsevier
    In:  Advances in Geophysics, ed.: Renata Dmowska, Heidelberg, Elsevier, vol. 47, no. 8, pp. 1-64, pp. 1516, (ISBN: 0-12-018847-3)
    Details
    Publication Date: 2005
    Keywords: Crustal deformation (cf. Earthquake precursor: deformation or strain) ; Subduction zone ; USA
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    BIBLIOGRAPHY SEISMOLOGY
  • 73
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    Acoustic and Elastic Wave Fields in Geophysics, III (2005)
    Elsevier
    In:  Amsterdam, 652 pp., Elsevier, vol. 39, no. XVI:, pp. 227-235, (0-444-51955-6)
    Details
    Publication Date: 2005
    Keywords: Seismics (controlled source seismology) ; Applied geophysics ; Wave propagation ; plane ; spherical ; and ; cylindrical ; Waves ; in ; isotropic ; and ; transversely ; isotropic ; solids, ; liquid-solid ; models, ; and ; media ; with ; cylindrical ; inclusions ; (boreholes) ; Textbook of geophysics
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    BIBLIOGRAPHY SEISMOLOGY
  • 74
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    Strengthening of Ti2AlC by substituting Ti with V (2005)
    Elsevier
    Details
    Publication Date: 2005-12-01
    Print ISSN: 1359-6462
    Electronic ISSN: 1872-8456
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 75
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    Effects of temperature on pressure infiltration of liquid Al and Al–12wt.%Si alloy into packed SiC particles (2005)
    Elsevier
    Details
    Publication Date: 2005-12-01
    Print ISSN: 1359-6462
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 76
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    Phase transformation in nickel during tribotesting (2005)
    Elsevier
    Details
    Publication Date: 2005-12-01
    Print ISSN: 1359-6462
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 77
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    Electron irradiation induced phase transformation in Zr66.7Cu33.3 and Zr66.7Pd33.3 metallic glass (2005)
    Elsevier
    Details
    Publication Date: 2005-12-01
    Print ISSN: 1359-6462
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  • 78
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    Fatigue crack propagation in an aluminium alloy at 223K (2005)
    Elsevier
    Details
    Publication Date: 2005-12-01
    Print ISSN: 1359-6462
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 79
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    Wetting and interface phenomena in the B4C/(Cu–B–Si) system (2005)
    Elsevier
    Details
    Publication Date: 2005-12-01
    Print ISSN: 1359-6462
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 80
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    Reversible orientation-biased grain growth in thin metal films induced by a focused ion beam (2005)
    Elsevier
    Details
    Publication Date: 2005-12-01
    Print ISSN: 1359-6462
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  • 81
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    Devitrification sequence map in the glass forming Al–Ni–Gd system (2005)
    Elsevier
    Details
    Publication Date: 2005-11-01
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  • 82
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    Comment on “Preparation and electrorheological property of alkaline earth metal compounds modified amorphous TiO2 electrorheological fluid” (2005)
    Elsevier
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    Publication Date: 2005-11-01
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  • 83
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    Magnetization effect on hydrogen absorption in high-strength steels and its implications (2005)
    Elsevier
    Details
    Publication Date: 2005-12-01
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  • 84
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    Chemical diffusion in bulk glass-forming Pd40Cu30Ni10P20 melts (2005)
    Elsevier
    Details
    Publication Date: 2005-12-01
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  • 85
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    Measurement of interfacial shear mechanical properties in thermal barrier coating systems by a barb pullout method (2005)
    Elsevier
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    Publication Date: 2005-11-01
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  • 86
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    A novel fiber Bragg grating acoustic emission sensor head for mechanical tests (2005)
    Elsevier
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    Publication Date: 2005-11-01
    Print ISSN: 1359-6462
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 87
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    Surface characteristics of porous titanium implants fabricated by environmental electro-discharge sintering of spherical Ti powders in a vacuum atmosphere (2005)
    Elsevier
    Details
    Publication Date: 2005-10-01
    Print ISSN: 1359-6462
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 88
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    Gallium-doped silicon nitride nanowires sheathed with amorphous silicon oxynitride (2005)
    Elsevier
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    Publication Date: 2005-10-01
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  • 89
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    Loading- and substructure-induced irreversibility in texture during route C equal channel angular extrusion (2005)
    Elsevier
    Details
    Publication Date: 2005-10-01
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  • 90
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    Neutron diffraction studies on lattice strain evolution around a crack-tip during tensile loading and unloading cycles (2005)
    Elsevier
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    Publication Date: 2005-10-01
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  • 91
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    Anomalies in resistivity, magnetic susceptibility and specific heat in iron-doped Ti–Ni shape memory alloys (2005)
    Elsevier
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    Publication Date: 2005-10-01
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  • 92
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    Effect of Ag on the microstructure and properties of Cu–Fe in situ composites (2005)
    Elsevier
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    Publication Date: 2005-11-01
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  • 93
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    New observations on the thermal arrest memory effect in Ni–Ti alloys (2005)
    Elsevier
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    Publication Date: 2005-10-01
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  • 94
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    On the preferential formation of anatase in amorphous titanium oxide film (2005)
    Elsevier
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    Publication Date: 2005-11-01
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  • 95
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    Theory for diffusional transformation kinetics: Multicomponent and multiphase systems (2005)
    Elsevier
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    Publication Date: 2005-11-01
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  • 96
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    Synthesis of dense nanocrystalline ZrO2–MgAl2O4 spinel composite (2005)
    Elsevier
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    Publication Date: 2005-11-01
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  • 97
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    In situ observations of the pest oxidation process of NbSi at 1023K (2005)
    Elsevier
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    Publication Date: 2005-09-01
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  • 98
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    Conduction type evolution during eutectoid decomposition of Mn-added α-FeSi alloy (2005)
    Elsevier
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    Publication Date: 2005-09-01
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  • 99
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    A new orientation relationship OR4 of icosahedral phase with magnesium matrix in Mg–Zn–Y alloys (2005)
    Elsevier
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    Publication Date: 2005-11-01
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  • 100
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    Experimental and simulation textures in an asymmetrically skin-passed zinc galvanized sheet (2005)
    Elsevier
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    Publication Date: 2005-09-01
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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