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  • 1
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    Role of crustal fluids and thermo-mechanical structure for lower crustal seismicity: The Gargano Promontory (southern Italy) (2023)
    Elsevier
    Details
    Publication Date: 2023-02-20
    Description: Several regions around the globe are characterized by a seismically active lower crust, at depths where litho­logical and thermal conditions suggest stress release by ductile flow. The Gargano Promontory (GP, southern Italy) is an example where a recently installed seismic network has recorded an intense seismic activity at depths between 20 and 30 km, i.e. in the lower crust. The GP is located in proximity of the Gargano-Dubrovnik line­ament, a seismogenic zone separating the central and southern Adriatic basins. These two basins constitute sites of sediments accumulation since Tertiary times. Another important basin in the region is represented by the Apennine foredeep, that includes the Candelaro area. We analyze the possible mechanisms controlling the dis­tribution of seismicity in the GP to identify the factors that make the lower crust seismically active. To this aim, we construct a thermo-rheological model of a layered continental crust, calibrated on the basis of geometrical, lithological and thermal constraints. The model takes into account various crustal lithologies, the presence of fluids in the crystalline basement, lateral variations of geotherm and stress field. The numerical simulations show that the presence of fluids is a key factor controlling the cluster of seismicity in the lower crust. Moreover, the presence of water in the upper crystalline basement and sedimentary cover provides a plausible explanation for upper crustal seismicity in a zone of very high heat flow SW of the GP. The distribution of the seismicity is probably affected by the composition of the crystalline basement, with mafic bodies injected into the crust during the Paleocene magmatic phase that affected the Mediterranean region. In addition, fluid accumulation and overpressure may occur along detachment levels in the lower crust, leading to clustering of the earthquakes. Based on our findings, we hypothesize that the presence of hydrous diapiric upwelling(s) in the upper mantle can feed a deep fluid circulation system, inducing lower crustal seismicity.
    Description: Published
    Description: 103929
    Description: 4T. Sismicità dell'Italia
    Description: JCR Journal
    Keywords: Lower crust ; Rheology ; Seismology ; Geotherm ; Numerical modeling ; Gargano Promontory (southern Italy)
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
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    Arsenic contamination at the Bagnoli Bay seabed (South Italy) via particle tracking numerical modeling: Pollution patterns from stationary climatic forcings (2023)
    Elsevier
    Details
    Publication Date: 2023-03-16
    Description: Almost 140 years of industrial exploitation have severely degraded the environment of Bagnoli Coroglio (BC), the westernmost neighborhood of the city of Naples (Italy). In this peculiar area, however, geogenic processes overlap with the impact of human activities, making it difficult to distinguish between anthropogenic and geogenic pollution sources. This is particularly true for Arsenic, the concentration of which in the marine sediments largely exceeds the tolerable level for human health and the background value for local pyroclastics. After several studies have used traditional tools based on multivariate statistics, this article attempts at tackling the problem via numerical modeling, which provides a deeper insight into the physics that governs the pollution process. Therefore, we use a particle tracking model to assess whether arsenic levels in the seabed can be affected by the influx of thermal water from an artificial channel outfalling at the westernmost part of the coast The climatic forcings that drive the marine circulation are simplified to basic "scenarios", in which wind and waves are stationary in strength and direction. Since the simulation time is much less than the contamination timescale, the comparison between numerical results and measurements is essentially qualitative and concerns the shape of contamination contours. It was found the primary forcing that enables seabed pollution is the tidal circulation, which, moreover, acts continuously in time. Quantitative arguments based on regression analysis suggest the discharge of thermal water explains almost a quarter of the observed pollution, which is consistent with previous research based on multivariate statistics.
    Description: This research results from a collaboration between the University of Naples Federico II and the National Institute of Geophysics and Vulcanology (INGV). The partnership is born in the frame of the multidisciplinary project ABBaCo, funded by the Italian Ministry of Education and Research, which aimed to provide innovative and environmentally friendly solutions for restoring the Bagnoli area.
    Description: Published
    Description: 134955
    Description: 9T. Geochimica dei fluidi applicata allo studio e al monitoraggio di aree sismiche
    Description: 3V. Proprietà chimico-fisiche dei magmi e dei prodotti vulcanici
    Description: 6A. Geochimica per l'ambiente e geologia medica
    Description: 1TR. Georisorse
    Description: 7SR AMBIENTE – Servizi e ricerca per la società
    Description: 2IT. Laboratori analitici e sperimentali
    Description: JCR Journal
    Keywords: Adsorption ; Arsenic contamination in marine sediments ; Diffusion in coastal waters ; Numerical modeling ; Particle tracking ; Sediments settling ; 03. Hydrosphere ; 03.02. Hydrology ; 03.04. Chemical and biological ; 04.04. Geology ; 04.08. Volcanology ; 05.08. Risk ; 05.06. Methods
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 3
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    Modelling and physico-chemical constraints to the 4.5 ka Agnano-Monte Spina Plinian eruption (Campi Flegrei, Italy) (2020)
    Elsevier
    Details
    Publication Date: 2023-07-18
    Description: The 4.5 ka trachytic Plinian eruption of Agnano-Monte Spina is the largest magnitude event of the past 5 ka at Campi Flegrei caldera. The complete eruptive sequence consists of six members, three of which, named A, B and D, are characterized by the association of fallout and pyroclastic density current (PDC) deposits well preserved at proximal locations. In this study, we analyze the textural characteristics of the pumice clasts of the three major fallout deposits (A1, B1, D1) and of their associated PDC deposits (A2, B2, D2), and link them to the physical properties of magma in order to investigate conduit fluid dynamics. A combination of data (field work, grain-size and density measurements, vesicle number densities and size distributions, crystal content, water content) is used to set up the source term conditions for numerical simulations. Each fall/PDC transition is accompanied by distinctive changes in textural properties of the juveniles, recognized by a lowering in vesicle number densities of about one order of magnitude (from 108 to 107 cm−3), indicating a significant decrease in the magma ascent rate. Melt inclusions show a marked decrease in volatile content recurrent at each fall/PDC transition and indicate that the three main pulses of the eruption were fed by distinct and progressively deeper magma batches. Numerical simulations, taking into account magma properties derived from the textural analyses, and variations in initial water content, show decreases in the exit velocities and Mass Discharge Rate (MDR) consistent with such fall/PDC transitions. Different initial water contents together with changes in conduit diameters allow us to simulate the different column heights reconstructed for the three Plinian phases. The reconstructed scenario for the Agnano-Monte Spina eruption involves a stop-start behavior and a top-down trigger for the most voluminous and intense eruptive episode D.
    Description: Published
    Description: 119301
    Description: 4V. Processi pre-eruttivi
    Description: JCR Journal
    Keywords: Campi flegrei ; Plinian eruptions ; Textural analysis ; VSD ; CSD ; Numerical modeling
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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