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  • 1
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    Developing an Event Tree for probabilistic hazard and risk assessment at Vesuvius (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Probabilistic characterizations of possible future eruptive scenarios at Vesuvius volcano are elaborated and organized within a risk-based framework. In the EXPLORIS project, a wide variety of topics relating to this basic problem have been pursued: updates of historical data, reinterpretation of previous geological field data and the collection of new fieldwork results, the development of novel numerical modelling codes and of risk assessment techniques have all been completed. To achieve coherence, many diverse strands of evidence had to be unified within a formalised structure, and linked together by expert knowledge. For this purpose, a Vesuvius ‘Event Tree’ (ET) was created to summarise in a numerical-graphical form, at different levels of detail, all the relative likelihoods relating to the genesis and style of eruption, development and nature of volcanic hazards, and the probabilities of occurrence of different volcanic risks in the next eruption crisis. The Event Tree formulation provides a logical pathway connecting generic probabilistic hazard assessment to quantitative risk evaluation. In order to achieve a complete parameterization for this all-inclusive approach, exhaustive hazard and risk models were needed, quantified with comprehensive uncertainty distributions for all factors involved, rather than simple ‘best-estimate’ or nominal values. Thus, a structured expert elicitation procedure was implemented to complement more traditional data analysis and interpretative approaches. The structure of the Vesuvius Event Tree is presented, and some of the data analysis findings and elicitation outcomes that have provided initial indicative probability distributions to be associated with each of its branches are summarized. The Event Tree extends from initiating volcanic eruption events and hazards right through to human impact and infrastructure consequences, with the complete tree and its parameterisation forming a quantitative synoptic framework for comprehensive hazard evaluation and mapping of risk impacts. The organization of the Event Tree allows easy updating, as and when new information becomes available
    Description: Published
    Description: 397-415
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: reserved
    Keywords: Vesuvius ; volcanic hazard ; volcanic risk ; probabilistic risk assessment ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
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    Dynamics of ash-dominated eruptions at Vesuvius: the post-512 AD AS1a event (2012)
    Springer-Verlag
    Details
    Publication Date: 2017-04-04
    Description: Recent stratigraphic studies at Vesuvius have revealed that, during the past 4,000 years, long lasting, moderate to low-intensity eruptions, associated with continuous or pulsating ash emission, have repeatedly occurred. The present work focuses on the AS1a eruption, the first of a series of ash-dominated explosive episodes which characterized the period between the two Subplinian eruptions of 472 AD and 1631 AD. The deposits of this eruption consist of an alternation of massive and thinly laminated ash layers and minor well sorted lapilli beds, reflecting the pulsatory injection into the atmosphere of variably concentrated ash-plumes alternating with Violent Strombolian stages. Despite its nearly constant chemical composition, the juvenile material shows variable external clast morphologies and groundmass textures, reflecting the fragmentation of a magma body with lateral and/or vertical gradients in both vesicularity and crystal content. Glass compositions and mineralogical assemblages indicate that the eruption was fed by rather homogeneous phonotephritic magma batches rising from a reservoir located at ~ 4 km (100 MPa) depth, with fluctuations between magma delivery and magma discharge. Using crystal size distribution (CSD) analyses of plagioclase and leucite microlites, we estimate that the transit time of the magma in the conduit was on the order of ~ 2 days, corresponding to an ascent rate of around 2 × 10−2 ms−1. Accordingly, assuming a typical conduit diameter for this type of eruption, the minimum duration of the AS1a event is between about 1.5 and 6 years. Magma fragmentation occurred in an inertially driven regime that, in a magma with low viscosity and surface tension, can act also under conditions of slow ascent.
    Description: Published
    Description: 699-715
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: JCR Journal
    Description: reserved
    Keywords: Ash emission activity ; Tephrite ; Vesuvius ; Stratigraphy ; Textural analyses ; 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)
    Type: article
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  • 3
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    The 512 AD eruption of Vesuvius: complex dynamics of a small scale subplinian event (2012)
    Springer-Verlag, Berlin/Heidelberg
    Details
    Publication Date: 2017-04-04
    Description: We describe the products of the hitherto poorly known 512 AD eruption at Vesuvius, Italy. The deposit records a complex sequence of eruptive events, and it has been subdivided into eight main units, composed of stratified scoria lapilli or thin subordinate ash-rich layers. All the units formed by deposition from tephra fallout, pyroclastic density currents of limited extent being restricted to the initial stages of the eruption (U2). The main part of the deposit (U3 and U5) is characterized by a striking grain size alternation of fine to coarse lapilli, similar to that often described for mid-intensity, explosive eruptions. The erupted products have a phonotephritic composition, with progressively less evolved composition from the base to the top of the stratigraphic sequence. Based on different dispersal, sedimentological and textural features of the products, we identify five phases related to different eruptive styles: opening phase (U1, U2), subplinian phase (U3 to U5), pulsatory phreatomagmatic phase (U6), violent strombolian phase (U7) and final ash-dominated phase (U8). A DRE volume of 0.025 km3 has been calculated for the total fallout deposit. Most of the magma was erupted during the subplinian phase; lithic dispersal data indicate peak column heights of between 10 and 15 km, which correspond to a mass discharge rate (MDR) of 5×106 kg s1. The lower intensity, violent strombolian phase coincided with the eruption of the least evolved magma; a peak column height of 69 km, corresponding to an MDR of 1×106 kg s1, is estimated from field data. Phreatomagmatic activity played a minor role in the eruption, only contributing to the ash-rich deposits of U1, U4, U6 and U8. The two most striking features of the 512 AD eruption are the recurrent shifting of the eruption style and the pulsatory nature of the subplinian phase. Basing on a large set of observational data, we propose a model to explain this complex dynamics, also observed in other eruptions of similar scale from Vesuvius and elsewhere. The inbalance between the rates of magma supply and magma eruption may have caused the frequent changes in the eruptive style. Conversely, the high frequency oscillations of magma discharge recorded by the deposits of the subplinian phase were possibly related to cyclic instabilities in the permeability of the low viscosity magma column, which modulated magma fragmentation and discharge.
    Description: Published
    Description: 789-810
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: reserved
    Keywords: Subplinian ; Vesuvius ; Magma fragmentation ; Phreatomagmatism ; Eruption dynamics ; 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)
    Type: article
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  • 4
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    Dynamics of ash-dominated eruptions at Vesuvius: the post-512 AD AS1a event (2011)
    Springer
    Details
    Publication Date: 2017-04-04
    Description: Recent stratigraphic studies at Vesuvius have revealed that, during the past 4,000 years, long lasting,moderate to low-intensity eruptions, associated with continuous or pulsating ash emission, have repeatedly occurred. The present work focuses on the AS1a eruption, the first of a series of ash-dominated explosive episodes which characterized the period between the two Subplinian eruptions of 472 AD and 1631 AD. The deposits of this eruption consist of an alternation of massive and thinly laminated ash layers and minor well sorted lapilli beds, reflecting the pulsatory injection into the atmosphere of variably concentrated ash-plumes alternating with Violent Strombolian stages. Despite its nearly constant chemical composition, the juvenile material shows variable external clast morphologies and groundmass textures, reflecting the fragmentation of a magma body with lateral and/or vertical gradients in both vesicularity and crystal content. Glass compositions and mineralogical assemblages indicate that the eruption was fed by rather homogeneous phonotephritic magma batches rising from a reservoir located at ~ 4 km (100 MPa) depth, with fluctuations between magma delivery and magma discharge. Using crystal size distribution (CSD) analyses of plagioclase and leucite microlites, we estimate that the transit time of the magma in the conduit was on the order of ~ 2 days, corresponding to an ascent rate of around 2× 10−2 ms−1. Accordingly, assuming a typical conduit diameter for this type of eruption, the minimum duration of the AS1a event is between about 1.5 and 6 years. Magma fragmentation occurred in an inertially driven regime that, in a magma with low viscosity and surface tension, can act also under conditions of slow ascent.
    Description: In press
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: JCR Journal
    Description: reserved
    Keywords: Ash emission activity ; Tephrite ; Vesuvius ; Stratigraphy ; Textural analyses ; 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)
    Type: article
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  • 5
    Electronic Resource
    Electronic Resource
    Post-collapse volcanic history of calderas on a composite volcano: an example from Roccamonfina, southern Italy (1992)
    Springer
    Bulletin of volcanology 54 (1992), S. 253-266 
    Details
    ISSN: 1432-0819
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Roccamonfina, part of the Roman Potassic Volcanic Province, is an example of a composite volcano with a complex history of caldera development. The main caldera truncates a cone constructed predominantly of this caldera may have been associated with one of the ignimbritic eruptions of the Brown Leucitic Tuff (BLT) around 385 000 yr BP. The Campagnola Tuff, the youngest ignimbrite of the BLT, however, drapes the caldera margin and must postdate at least the initial stages of collapse. During the subsequent history of the caldera there were several major explosive eruptions. The largest of these was that of the Galluccio Tuff at about 300 000 yr BP. It is likely that there was further collapse within the main caldera associated with these eruptions. It is of note that despite these subsequent major explosive eruptions later collapse occurred within the confines of the main caldera. Between eruptions caldera lakes developed producing numerous lacustrine beds within the caldera fill. Extensive phases of phreatomagmatic activity generated thick sequences of pyroclastic surge and fall deposits. Activity within the main caldera ended with the growth of a large complex of basaltic trachyandestite lava domes around 150 000 yr BP. Early in the history of Roccamonfina sector collapse on the northern flank of the volcano formed the northern caldera. One of the youngest major events on Roccamonfina occurred at the head of this northern caldera with explosive activity producing the Conca Ignimbrite and associated caldera. There is no evidence that there was any linkage in the plumbing systems that fed eruptions in the main and northern calderas.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00301481
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  • 6
    Electronic Resource
    Electronic Resource
    The emplacement of intermediate volume ignimbrites: A case study from Roccamonfina Volcano, Southern Italy (1993)
    Springer
    Bulletin of volcanology 55 (1993), S. 467-480 
    Details
    ISSN: 1432-0819
    Keywords: Italy ; Roccamonfina ; Ignimbrite emplacement ; co-ignimbrite lithic breccias ; ground surges ; internal shear ; overriding flows
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract A model is presented for the emplacement of intermediate volume ignimbrites based on a study of two ∼6 km3 volume ignimbrites on Roccamonfina Volcano, Italy. The model considers that the flows were slow moving, and quickly deflated from turbulent to non-turbulent conditions. Yield strength and density increased whereas fluidisation decreased with time and runout of the pyroclastic flows. In proximal locations, on the caldera rim, heterogeneous exposures including discontinuous lithic breccias, stratified and cross-stratified units interbedded with massive ignimbrite suggest deposition from turbulent flows. In medial locations thick, massive ignimbrite occurs associated with three types of co-ignimbrite lithic breccia which we interpret as being emplaced by non-turbulent flows. Multiple grading of different breccia/lithic concentration types within single flow units indicates that internal shear occurred producing overriding or overlapping of the rear of the flow onto the slower-moving front part. This overriding of different parts of non-turbulent pyroclastic flows could be caused by at least two different mechanisms: (1) changes in flow regime, such as hydraulic jumps that may occur at breaks in slope; and (2) periods of increased discharge rate, possibly associated with caldera collapse, producing fresh pulses of lithic-rich material that sheared onto the slower-moving part of the flow in front. We propose that ground surge deposits enriched in pumice compared with their associated ignimbrite probably formed by a flow separation mechanism from the top and front of the pyroclastic flow. These turbulent clouds moved ahead of the non-turbulent lower part of the flow to form stratified pumice-rich deposits. In distal regions well-developed coarse, often clast-supported, pumice concentrations zones and coarse intra-flow-unit lithic concentrations occur within the massive ignimbrite. We suggest that the flows were non-turbulent, possessed a relatively high yield strength and may have moved by plug flow prior to emplacement.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00304590
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  • 7
    Electronic Resource
    Electronic Resource
    A facies interpretation of the eruption and emplacement mechanisms of the upper part of the Neapolitan Yellow Tuff, Campi Flegrei, southern Italy (1993)
    Springer
    Bulletin of volcanology 55 (1993), S. 311-326 
    Details
    ISSN: 1432-0819
    Keywords: Neapolitan Yellow Tuff ; lithofacies ; phreatomagmatic ; inverse-grading ; traction carpets ; hydraulic jumps ; depositional units
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract This study focuses on the upper part, Member B, of the Neapolitan Yellow Tuff (NYT). Detailed measurements of stratigraphic sections within the unlithified ‘pozzolana’ facies show that Member B is composed of at least six distinct depositional units which each record a complex fluctuation between different styles of deposition from pyroclastic density flows. Six lithofacies have been identified: (1) massive valleyponded facies, the product of non-turbulent flows; (2) inverse-graded facies formed by flows that were turbulent for the majority of transport but were deposited through a non-tubulent basal regime; (3) regressive sand-wave facies, the product of high-concentration, turbulent flows; (4) stratified facies, the product of deposition from turbulent, low-particle-concentration, flows; (5) particle aggregate and (6) vesicular ash lithofacies, both of which are considered to have formed by deposition from turbulent, low-concentration flows. Although the whole eruption may have been phreatomagmatic, facies 1–4 are interpreted to be the product of dry eruptive activity, whereas facies 5 and 6 are considered to be of wet phreatomagmatic eruptive phases. Small-scale horizontal variations between facies include inverse-graded lithofacies that pass laterally into regressive sand-wave structures and stratified deposits. This indicates rapid transition from non-turbulent to turbulent deposition within the same flow. Thin vesicular ash and particle aggregate layers pass laterally into massive valley-ponded vesicular lithofacies, suggesting contemporaneous wet pyroclastic surges and cohesive mud flows. Three common vertical facies relations were recognised. (1) Massive valley-ponded and inverse-graded facies are overlain by stratified facies, suggesting decreasing particle concentration with time during passage of a flow. (2) Repeated vertical gradation from massive up into stratified facies and back into massive beds, is indicative of flow fluctuating between non-turbulent and turbulent depositional conditions. (3) Vertical alternation between particle aggregates and vesicular facies is interpreted as the product of many flow pulses, each of which involved deposition of a single particle aggregate and vesicular ash layer. It is possible that the different facies record stages in a continuum of flow processes. The deposits formed are dependent on the presence, thickness and behaviour of a high-concentration, non-turbulent boundary layer at the base of the flow. The end members of this process are (a) flows that transported and deposited material from a non-turbulent flow regime and (b) flows that transported and deposited material from a turbulent flow regime.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00301143
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  • 8
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    An inclined Vulcanian explosion and associated products (2015)
    Geological Society of London
    Details
    Publication Date: 2015-05-02
    Description: Vulcanian explosions generate some of the most hazardous types of volcanic phenomena, including pyroclastic density currents. Non-vertical directionality of an explosion promotes asymmetrical distribution of proximal hazards around the volcano. Although critical, such behaviour is relatively uncommon and has been seldom documented. Here we present, for the first time, evidence both from geophysical monitoring and field survey data that records the occurrence of such an event. Thermal imagery captures a Vulcanian explosion at Soufrière Hills Volcano, Montserrat, which occurred during a large partial lava dome collapse in February 2010, and was inclined at about 25° from the vertical in a northerly direction. Pyroclastic products were preferentially distributed to the north and included: an unusual pumice boulder deposit that we propose was formed by a dilute pyroclastic density current; pumice flow deposits; and a proximal lapilli and block fallout lobe. The inclined nature of the explosion is attributed to the asymmetric geometry around the vent. The explosion-derived pyroclastic density currents had notably lower velocities than those associated with lateral blasts, which, we suggest, result from a separate and distinct mechanism. These inclined explosions present an additional mechanism that is able to generate directed pyroclastic density currents, with consequent implications for hazard assessment.
    Print ISSN: 0016-7649
    Topics: Geosciences
    Published by Geological Society of London
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  • 9
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    The Evolution of the Silver Hills Volcanic Center, and Revised40Ar/39Ar Geochronology of Montserrat, Lesser Antilles, With Implications for Island Arc Volcanism (2018)
    American Geophysical Union
    Details
    Publication Date: 2018-02-01
    Electronic ISSN: 1525-2027
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Published by American Geophysical Union
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  • 10
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    Malondialdehyde excretion by subjects consuming cod liver oil vs a concentrate of n-3 fatty acids (1988)
    Springer
    Details
    Publication Date: 1988-04-01
    Print ISSN: 0024-4201
    Electronic ISSN: 1558-9307
    Topics: Biology , Chemistry and Pharmacology
    Published by Springer
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