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  • 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
  • Etna
  • Elsevier Science Limited  (18)
  • Nature Publishing Group  (4)
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  • 1
    Publication Date: 2021-06-25
    Description: In this paper, the relationship between the dike-forming magmatic intrusions and the faulting process at Mount Etna is investigated in terms of Coulomb stress changes. As case study, a complete time-dependent 3-D finite element model for the 2002-2003 eruption at Mount Etna is presented. In the model, which takes into account the topography, medium heterogeneities and principal fault systems in a viscoelastic/plastic rheology, we sequentially activated three dike-forming processes and looked at the induced temporal evolution of the Coulomb stress changes, during the co-intrusive and post-intrusive periods, on Pernicana and Santa Venerina faults. We investigated where and when fault slips were encouraged or not, and consequently how earthquakes may have been triggered. Results show positive Coulomb stress changes for the Pernicana Fault in accordance to the time, location and depth of the 27th October 2002 Pernicana earthquake (Md = 3.5). The amount of Coulomb stress changes in the area of Santa Venerina Fault, as induced by dike-forming intrusions only, is instead almost negligible and, probably, not sufficient to trigger the 29th October Santa Venerina earthquake (Md = 4.4), occurred two days after the start of the eruption. The necessary Coulomb stress change value to trigger this earthquake is instead reached if we consider it as induced by the 27th October Pernicana biggest earthquake, combined with the dike-induced stresses.
    Description: MED-SUV FP7 Project (Grant number 308665)
    Description: Published
    Description: 185-196
    Description: 4V. Dinamica dei processi pre-eruttivi
    Description: JCR Journal
    Description: restricted
    Keywords: Coulomb stress changes ; Finite Element Model ; Viscoelasticity ; Earthquakes ; Mount Etna ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations ; 04. Solid Earth::04.03. Geodesy::04.03.06. Measurements and monitoring ; 04. Solid Earth::04.03. Geodesy::04.03.07. Satellite geodesy ; 04. Solid Earth::04.03. Geodesy::04.03.08. Theory and Models ; 04. Solid Earth::04.06. Seismology::04.06.02. Earthquake interactions and probability ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.01. Computational geophysics::05.01.03. Inverse methods
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
    Publication Date: 2020-12-18
    Description: Viscosity (η), glass transition (Tg) and heat capacity (Cp) of Etna trachybasalt and Fondo Riccio latite (Phlegrean Fields, Italy)were determined at lowand high temperatures for dry, hydrous and CO2 bearing samples.High temperature experiments have been performed in the range of 1499 to 1700 K by concentric cylindermeasurements, while low temperature experiments were carried out in the interval between 633 and 1093 K using the micropenetration technique. Glass transition temperature and glassy and liquid heat capacitieswere investigated using differential scanning calorimetry (DSC) up to 955 K. The H2O content in themelts ranged from nominally dry to 6.32 wt.%, while CO2 ranged from 229 to 1907 ppm. We combined low- and high-temperature viscosities and parameterized them by the use of a modified Vogel– Fulcher–Tamman equation,which accommodates the non-Arrhenian temperature dependence ofmelt viscosity. Experimental measurements showthat melt viscosity decreaseswith increasing temperature and water and CO2 contents. For latitic samples at 893 K, the introduction of CO2 (up to 732 ppm) decreases the liquid viscosity up to one order of magnitude with respect to the measured viscosity for H2O-bearing liquid. Moreover, the results of calorimetric measurements indicate that the glass transition temperature decreaseswith increasing volatile content (H2O+CO2). The glass transition temperature decreases by about 25 K by adding up to 1907 ppmof CO2 in the trachybasaltic samples. No appreciable effect on glassy [Cpg (Tg)] and liquid (Cpliq) heat capacities was observed with the addition of water and CO2. Structural and volcanological implications (i.e. volatile speciation and melt fragility) for water and CO2 dissolution in silicate melts are discussed in light of the presented results.
    Description: Published
    Description: 72-86
    Description: 3V. Dinamiche e scenari eruttivi
    Description: JCR Journal
    Description: reserved
    Keywords: Viscosity ; glass transition ; Etna ; Phlegrean Fields ; volatiles ; 04. Solid Earth::04.08. Volcanology::04.08.02. Experimental volcanism
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 3
    Publication Date: 2021-03-01
    Description: Strombolian activity is common in low-viscosity volcanism. It is characterised by quasi-periodic, short-lived explosions, which, whilst typically weak, may vary greatly in magnitude. The current paradigm for a strombolian volcanic eruption postulates a large gas bubble (slug) bursting explosively after ascending a conduit filled with low-viscosity magma. However, recent studies of pyroclast textures suggest the formation of a region of cooler, degassed, more-viscous magma at the top of the conduit is a common feature of strombolian eruptions. Following the hypothesis that such a rheological impedance could act as a ‘viscous plug’, which modifies and complicates gas escape processes, we conduct the first experimental investigation of this scenario. We find that: 1) the presence of a viscous plug enhances slug burst vigour; 2) experiments that include a viscous plug reproduce, and offer an explanation for, key phenomena observed in natural strombolian eruptions; 3) the presence and extent of the plug must be considered for the interpretation of infrasonic measurements of strombolian eruptions. Our scaled analogue experiments show that, as the gas slug expands on ascent, it forces the underlying low-viscosity liquid into the plug, creating a low-viscosity channel within a high-viscosity annulus. The slug's diameter and ascent rate change as it enters the channel, generating instabilities and increasing slug overpressure. When the slug reaches the surface, a more energetic burst process is observed than would be the case for a slug rising through the low-viscosity liquid alone. Fluid-dynamic instabilities cause low and high viscosity magma analogues to intermingle, and cause the burst to become pulsatory. The observed phenomena are reproduced by numerical fluid dynamic simulations at the volcanic scale, and provide a plausible explanation for pulsations, and the ejection of mingled pyroclasts, observed at Stromboli and elsewhere.
    Description: European Union’s Seventh Framework Programme (FP7/2007–2013) project NEMOH, REA grant agreement No. 289976
    Description: Published
    Description: 210-218
    Description: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Description: 3V. Dinamiche e scenari eruttivi
    Description: JCR Journal
    Description: restricted
    Keywords: analogue modeling ; strombolian explosions ; plugged vents ; volcano acoustic ; volcano infrasonic ; slug bursting ; Taylor bubble ; 04. Solid Earth::04.03. Geodesy::04.03.06. Measurements and monitoring ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 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 ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 4
    Publication Date: 2021-03-12
    Description: tGeological studies and morphological analysis, compared with seismological and geodetic data, suggestthat a compressive regime currently occurs at crustal depth in the western sector of Mt. Etna, accommo-dated by shallow thrusting and folding at the front of the chain, south of the volcanic edifice. In particular,a large WSW-ENE trending anticline, interpreted as detachment fold, is growing west and north of Cata-nia city (the Catania anticline). Geological data suggest that during the last 6000 years the frontal foldhas been characterized by uplift rates of ∼6 mm/yr along the hinge, consistent with the interferometricdata (10 mm/yr) recorded in the last 20 years. Moreover, a NNW-SSE oriented axis of compression hasbeen obtained by seismological data, consistent with GPS measurements over the last 20 years whichhave revealed a shortening rate of ∼5 mm/yr along the same direction. Besides the activity related to thevolcanic feeding system, the seismic pattern under the Mt. Etna edifice can be certainly related to theregional tectonics. The compressive stress is converted into elastic accumulation and then in earthquakesalong the ramps beneath the chain, whereas on the frontal area it is accommodated by aseismic defor-mation along an incipient detachment within the clayish foredeep deposits. The high rate of shorteningat the aseismic front of the chain, suggests a greater “seismic efficiency” in correspondence of ramps atthe rear.
    Description: Published
    Description: 32-41
    Description: 2T. Tettonica attiva
    Description: JCR Journal
    Description: restricted
    Keywords: Etna ; sicilian basal thrust ; 04. Solid Earth::04.04. Geology::04.04.01. Earthquake geology and paleoseismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 5
    Publication Date: 2021-05-12
    Description: Here we report the first measurements of gas masses released during a rare period of strombolian activity at the Bocca Nuova crater, Mt. Etna, Sicily. UV camera data acquired for 195 events over an ≈27 minute period (27th July 2012) indicate erupted SO2 masses ranging from ≈0.1 to ≈14 kg per event, with corresponding total gas masses of ≈0.1 to 74 kg. Thus, the activity was characterised by more frequent and smaller events than typically associated with strombolian activity on volcanoes such as Stromboli. Events releasing larger measured gas masses were followed by relatively long repose periods before the following burst, a feature not previously reported on from gas measurement data. If we assume that gas transport within the magma can be represented by a train of rising gas pockets or slugs, then the high frequency of events indicates that these slugs must have been in close proximity. In this case the longer repose durations associated with the larger slugs would be consistent with interactions between adjacent slugs leading to coalescence, a process expedited close to the surface by rapid slug expansion. We apply basic modelling considerations to the measured gas masses in order to investigate potential slug characteristics governing the observed activity.We also cross correlated the acquired gas fluxes with contemporaneously obtained seismic data but found no relationship between the series in line with the mild form of manifest explosivity.
    Description: Published
    Description: 103–111
    Description: 3V. Dinamiche e scenari eruttivi
    Description: JCR Journal
    Description: open
    Keywords: Mild strombolian activity ; Ultra-violet imaging ; Volcanic gas measurements ; Slug dynamics ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 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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  • 6
    Publication Date: 2020-12-15
    Description: The source properties of the Long-Period events that occurred at Campi Flegrei Caldera (Italy) during the 2004–2006 ground uplift episode are investigated by analyzing the temporal release of seismic energy, amplitude distribution and inter-event occurrence time. Moreover, an entropy-based decomposition method is applied to identify the simpler waveforms thought to be representative of the source mechanism of Long-Period events. On the basis of the outcomes, we propose that the main part of these events is the result of a source process triggered by a mechanism of fluid charge/discharge, which causes pressure drop in a main branch of a dentritic network of the hydrothermal system. In this model, the rate of the Poissonian process (about 15 min), which drives the occurrence of the Long-Period events, provides the average recharge time of the system up to the critical condition. A partial shunting of the fluid flow away from the main conduit activates the ”resonance” of a second branch, spatially separated from the first one. This is a process that occurs whenever the fluid pressure exceeds a critical value and produces less energetic Long-Period events. The mechanism of pressure variation in the two conduits generates signals with preferred amplitude scales, described by a bi-lognormal distribution. From a dynamical point of view, Long-Period events result well described by a low-dimensional dynamical system. Finally, the time pattern of the energy release and its correlation with the diurnal solid earth tide suggest that the whole mechanism of fluid charge/discharge is likely modulated by tidal stress variation.
    Description: Published
    Description: 16-30
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: partially_open
    Keywords: Lp sources ; Poissonian occurrence ; Tidal modulation ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 7
    Publication Date: 2017-04-04
    Description: From October 2008 to November 2009, soil CO2, radon and structural field surveys were performed on Mt. Etna, in order to acquire insights into active tectonic structures in a densely populated sector of the south-eastern flank of the volcano, which is involved in the flank dynamics, as highlighted by satellite data (InSAR). The studied area extends about 150 km2, in a sector of the volcano where InSAR results detected several lineaments that were not well-defined from previous geological surveys. In order to validate and better constrain these features with ground data evidences, soil CO2 and soil radon measurements were performed along transects roughly orthogonal to the newly detected faults, with measurement points spaced about 100 m. In each transect, the highest CO2 values were found very close to the lineaments evidenced by InSAR observations. Anomalous soil CO2 and radon values were also measured at old eruptive fractures. In some portions of the investigated area soil gas anomalies were rather broad over transects, probably suggesting a complex structural framework consisting of several parallel volcano-tectonic structures, instead of a single one. Soil gas measurements proved particularly useful in areas at higher altitude on Mt. Etna (i.e. above 900 m asl), where InSAR results are not very informative/ are fairly limited, and allowed recognizing the prolongation of some tectonic lineaments towards the summit of the volcano. At a lower altitude on the volcanic edifice, soil gas anomalies define the active structures indicated by InSAR results prominently, down to almost the coastline and through the northern periphery of the city of Catania. Coupling InSARwith soil gas prospectingmethods has thus proved to be a powerful tool in detecting hidden active structures that do not show significant field evidences.
    Description: This work was funded by the DPC-INGV project “Flank”
    Description: Published
    Description: 27-40
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: reserved
    Keywords: CO2 ; Radon ; InSAR ; Faults ; Etna ; Volcano-tectonics ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations ; 04. Solid Earth::04.03. Geodesy::04.03.07. Satellite geodesy ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 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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  • 8
    Publication Date: 2017-04-04
    Description: In this paper, we describe the 1809 eruption of Mt. Etna, Italy, which represents one historical rare case in which it is possible to observe details of the internal structure of the feeder system. This is possible thanks to the presence of two large pit craters located in the middle of the eruptive fracture field that allow studying a section of the shallow feeder system. Along the walls of one of these craters, we analysed well-exposed cross sections of the uppermost 15–20 m of the feeder system and related volcanic products. Here, we describe the structure, morphology and lithology of this portion of the 1809 feeder system, including the host rock which conditioned the propagation of the dyke, and compare the results with other recent eruptions. Finally, we propose the dynamic model of the magma behaviour inside a laterally-propagating feeder dyke, demonstrating how this dynamic triggered important changes in the eruptive style (from effusive/Strombolian to phreatomagmatic) during the same eruption. Our results are also useful for hazard assessment related to the development of flank eruptions, potentially the most hazardous type of eruption from basaltic volcanoes in densely urbanized areas, such as Mt. Etna.
    Description: Published
    Description: 1-11
    Description: 2T. Tettonica attiva
    Description: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Description: 3V. Dinamiche e scenari eruttivi
    Description: 4V. Vulcani e ambiente
    Description: 6A. Monitoraggio ambientale, sicurezza e territorio
    Description: N/A or not JCR
    Description: open
    Keywords: feeder dyke ; basaltic volcanoes ; flank eruptions ; Etna ; volcanic hazards ; sill ; volcanic rift ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.04. Thermodynamics ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 9
    Publication Date: 2020-02-24
    Description: The reinterpretation of more than 2500 subsurface data, consisting of geoelectric and borehole prospecting undertaken at Mount Etna, allows reconstructing the contour map of the sedimentary basement. This reconstruction highlights a complex asymmetric topography due to the inhomogeneous long-term updoming of the region and the interrelationship between the development of the drainage network and flank instability. These different processes have produced a major morphological difference between the eastern sector, characterised by a 17 km-wide horseshoe-shaped depression, and the other flanks formed by palaeovalleys. The origin of the wide horseshoe-shaped depression can be attributed to the large-scale flank instability processes involving the entire continental margin in the Etna offshore. This depression of the Etna basement was generated by a series of coalescent landslides before the beginning of the eruptive activity of the Timpe phase more than 220 ka ago. This wide depression is the main cause of the flank instability that produced the gravitational slope failures of the Valle del Bove about 10 ka ago. Regarding Mt Etna's geometry, we have estimated a total volume of about 532 km3 that was emplaced during the past 330 ka, resulting in an average rate of volcanic output of 0.0016 km3/a. The reconstruction of the temporal variation of the average eruptive rate highlights a drastic increase of volcanism during the last 100 ka in response to the gradual stabilization of the plumbing system in the Etna region that led to the build-up of the composite stratovolcano structure. The data presented in this paper represent the state of knowledge of the sedimentary basement of Etna, which can be used for future studies aimed at developing a detailed understanding of the deep structure of the volcano's unstable flanks.
    Description: Published
    Description: 46-64
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: restricted
    Keywords: Etna ; Basement ; Stratigraphy ; Morphostructural ; Volcanic output ; Flank instability ; 04. Solid Earth::04.07. Tectonophysics::04.07.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 10
    Publication Date: 2020-05-29
    Description: Deep drilling is a key tool for the investigation of active volcanoes in the modern Earth Sciences, as this provides the only means to obtain direct information on processes that occur at depth. Data acquired from drilling projects are fundamental to our understanding of volcano dynamics, and for mitigation of the hazards they pose for millions of people who live close to active volcanoes. We present here the first borehole measurement of the stress field in the crust of Campi Flegrei (southern Italy), a large active caldera, and one of the highest risk volcanoes worldwide. Measurements were performed to depths of ∼500m during a pilot study for the Campi Flegrei Deep Drilling Project. These data indicate an extensional stress field, with a minimum horizontal stress of ca. 75% to 80% of the maximum horizontal stress, which is approximately equal to the vertical stress. The deviation from lithostatic conditions is consistent with a progressive increase in applied horizontal stress during episodes of unrest, since at least 1969. As the stress field is evolving with time, the outcome of renewed unrest cannot be assessed by analogy with previous episodes. Interpretations of future unrest must therefore accommodate the possibility that Campi Flegrei is approaching conditions that are more favourable to a volcanic eruption than has previously been the case. Such long-term accumulation of stress is not expected to be unique to Campi Flegrei, and so might provide a basis for improved forecasts of eruptions at large calderas elsewhere.
    Description: Published
    Description: 23-29
    Description: 6T. Sismicità indotta e caratterizzazione sismica dei sistemi naturali
    Description: 4V. Vulcani e ambiente
    Description: 5A. Energia e georisorse
    Description: 7A. Geofisica di esplorazione
    Description: JCR Journal
    Description: restricted
    Keywords: Campi Flegrei ; stress ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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