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  • 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks
  • INGV  (4)
  • Nature Publishing Group  (2)
  • Molecular Diversity Preservation International
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  • 1
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    Local stresses, dyke arrest and surface deformation in volcanic edificesand rift zones (2006)
    INGV
    Details
    Publication Date: 2021-06-15
    Description: Field studies indicate that nearly all eruptions in volcanic edifices and rift zones are supplied with magma through fractures (dykes) that are opened by magmatic overpressure. While (inferred) dyke injections are frequent during unrest periods, volcanic eruptions are, in comparison, infrequent, suggesting that most dykes become arrested at certain depths in the crust, in agreement with field studies. The frequency of dyke arrest can be partly explained by the numerical models presented here which indicate that volcanic edifices and rift zones consisting of rocks of contrasting mechanical properties, such as soft pyroclastic layers and stiff lava flows, commonly develop local stress fields that encourage dyke arrest. During unrest, surface deformation studies are routinely used to infer the geometries of arrested dykes, and some models (using homogeneous, isotropic half-spaces) infer large grabens to be induced by such dykes. Our results, however, show that the dyke-tip tensile stresses are normally much greater than the induced surface stresses, making it difficult to explain how a dyke can induce surface stresses in excess of the tensile (or shear) strength while the same strength is not exceeded at the (arrested) dyke tip. Also, arrested dyke tips in eroded or active rift zones are normally not associated with dyke-induced grabens or normal faults, and some dykes arrested within a few metres of the surface do not generate faults or grabens. The numerical models show that abrupt changes in Young's moduli(stiffnesses), layers with relatively high dyke-normal compressive stresses (stress barriers), and weak horizontal contacts may make the dyke-induced surface tensile stresses too small for significant fault or graben formation to occur in rift zones or volcanic edifices. Also, these small surface stresses may have no simple relation to the dyke geometry or the depth to its tip. Thus, for a layered crust with weak contacts, straightforward inversion of surface geodetic data may lead to unreliable geometries of arrested dykes in active rift zones and volcanic edifices.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: dyke injection ; dyke arrest ; crustalstresses ; crustal layering ; surface deformation ; volcanic hazard ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 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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  • 2
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    Il Somma Vesuvio: storia eruttiva e impatto delle sue eruzioni sul territorio (2013)
    INGV
    Details
    Publication Date: 2017-04-04
    Description: Il Somma-Vesuvio insieme a Campi Flegrei, Procida e Ischia è uno dei quattro vulcani presenti nell’area napoletana (Fig. 1). Fin dall’ultima eruzione, avvenuta nel marzo 1944, il vulcano è quiescente e caratterizzato solo da moderate emissioni fumaroliche e sismicità, prevalentemente concentrate in area craterica. La storia passata del vulcano suggerisce che la quiescenza può culminare in un eruzione esplosiva che, potenzialmente, può interessare aree molto vaste. Solo nelle immediate vicinanze del vulcano, cioè entro un raggio di 10 km, risiedono circa 600.000 persone, potenzialmente esposte agli effetti significativi di fenomeni vulcanici, quali scorrimento di colate piroclastiche, accumulo di grossi spessori di depositi da caduta e scorrimento di lahars. Questa breve nota ha lo scopo di illustrare, per grandi linee, la storia eruttiva del Somma-Vesuvio, la sua evoluzione morfologica e strutturale e l’impatto delle sue eruzioni sul territorio.
    Description: Published
    Description: 14-21
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: N/A or not JCR
    Description: open
    Keywords: Somma-Vesuvio ; Impatto sul territorio ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 3
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    Dynamic feeder dyke systems in basaltic volcanoes: the exceptional example o fthe 1809 Etna eruption (Italy) (2015)
    Nature Publishing Group
    Details
    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)
    Type: article
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  • 4
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    Constraining the dynamics of volcanic eruptions by characterization of pumice textures (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: We have characterized the textures of pumice clasts from Phlegraean Fields to gain insights into the conduit flow-dynamics of alkaline explosive eruptions. Vesicularities, vesicle number densities, and vesicle sizes and shapes were measured to obtain the bulk and groundmass properties of the juvenile fraction of Campanian Ignimbrite (CI) and Agnano Monte Spina (AMS) eruptions. The results report the coexistence of three end-member pumice types in the deposits of both eruptions, 1) microvesicular, 2) tube and 3) expanded, which differ according to clast morphology and the macro- to microscopic vesicle texture. Vesicularities (0.85-0.94 for CI, 0.51-0.91 for AMS) and vesicle number densities (2-4×105 cm-2 in CI, 3×105-106 cm-2 in AMS) span quite a wide range in all the three pumice types. Overall, tube pumices exhibit the highest bulk (0.89) and groundmass (CI 0.85, AMS 0.82) average vesicle volume fractions but the lowest average vesicle number densities (CI 2×105, AMS 4×105 cm-2). Comparison with textures of calc-alkaline pumices has revealed many similarities and points to a common origin and distribution of the products from both magma compositions within the volcanic conduit. In addition, the results of the textural analysis were interpreted in the light of the conduit flow modeling of Phlegraean Fields eruptions. The comparison of textural observations with results from simulations of conduit magma ascent has exhibited a good agreement between measured and numerically calculated vesicularities for both compositions, helping to constrain the overall dynamics of alkaline versus calc-alkaline eruptions.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: Phlegraean Fields ; Plinian eruptions ; vesicle textures ; magma ascent dynamics ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 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)
    Type: article
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  • 5
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    Rapid differentiation in a sill-like magma reservoir: a case study from the campi flegrei caldera (2012)
    Nature Publishing Group
    Details
    Publication Date: 2017-04-04
    Description: In recent decades, geophysical investigations have detected wide magma reservoirs beneath quiescent calderas. However, the discovery of partially melted horizons inside the crust is not sufficient to put constraints on capability of reservoirs to supply cataclysmic eruptions, which strictly depends on the chemical-physical properties of magmas (composition, viscosity, gas content etc.), and thus on their differentiation histories. In this study, by using geochemical, isotopic and textural records of rocks erupted from the high-risk Campi Flegrei caldera, we show that the alkaline magmas have evolved toward a critical state of explosive behaviour over a time span shorter than the repose time of most volcanic systems and that these magmas have risen rapidly toward the surface. Moreover, similar results on the depth and timescale of magma storage were previously obtained for the neighbouring Somma-Vesuvius volcano. This consistency suggests that there might be a unique long-lived magma pool beneath the whole Neapolitan area.
    Description: Published
    Description: article 712
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: 3.6. Fisica del vulcanismo
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: N/A or not JCR
    Description: open
    Keywords: magma ; campi flegrei caldera ; 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 ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 6
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    Assetto geologico-strutturale ed evoluzione vulcanologica dell’isola d’Ischia (2013)
    INGV
    Details
    Publication Date: 2017-04-04
    Description: L’isola d’Ischia è la parte emersa di un esteso apparato vulcanico, che si erge per oltre 1.000 m dal fondo del mare, nel settore nord-occidentale del Golfo di Napoli [Bruno et al., 2002]. Unitamente alla caldera dei Campi Flegrei e all’isola di Procida, Ischia costituisce il cosiddetto Distretto Vulcanico Flegreo [Orsi et al., 1996; 2003; Fig. 1]. La genesi e la risalita dei magmi in questo distretto, e più in generale nell’intera area vulcanica campana, sono da mettersi in relazione ai processi tettonici estensionali Plio- Quaternari che hanno determinato la formazione del graben della Piana Campana, lungo il margine tirrenico della catena appenninica [Ippolito et al., 1973; D’Argenio et al., 1973: Finetti e Morelli, 1974; Bartole, 1984; Piochi et al., 2005; Orsi et al., 2003; de Vita e Marotta, 2007]. Nel corso di tali processi, la formazione di faglie dirette ad andamento NW-SE e di faglie di trasferimento da dirette a trascorrenti, ad andamento NESW, ha determinato lo smembramento del graben in una serie di blocchi e la conseguente risalita dei magmi attraverso la crosta [Carrara et al., 1973; 1974; Finetti e Morelli, 1974; Funiciello et al., 1976; Mariani e Prato, 1988; Faccenna et al., 1994].
    Description: Published
    Description: 27-32
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: N/A or not JCR
    Description: open
    Keywords: storia geologica ; Isola D'Ischia ; 04. Solid Earth::04.04. Geology::04.04.10. Stratigraphy ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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