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  • Articles  (6)
  • Numerical modeling  (6)
  • Elsevier  (6)
  • 2020-2024  (3)
  • 2015-2019  (3)
  • 1975-1979
  • 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)
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  • 4
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    Transient numerical model of magma ascent dynamics: application to the explosive eruptions at the Soufrière Hills Volcano (2018)
    Elsevier
    Details
    Publication Date: 2021-06-30
    Description: Volcanic activity exhibits a wide range of eruption styles, from relatively slow effusive eruptions that produce lava flows and lava domes, to explosive eruptions that can inject large volumes of fragmented magma and volcanic gases high into the atmosphere. Although controls on eruption style and scale are not fully understood, previous research suggests that the dynamics of magma ascent in the shallow subsurface (〈 10 km depth) may in part control the transition from effusive to explosive eruption and variations in eruption style and scale. Here we investigate the initial stages of explosive eruptions using a 1D transient model for magma ascent through a conduit based on the theory of the thermodynamically compatible systems. The model is novel in that it implements finite rates of volatile exsolution and velocity and pressure relaxation between the phases. We validate the model against a simple two-phase Riemann problem, the Air-Water Shock Tube problem, which contains strong shock and rarefaction waves. We then use the model to explore the role of the aforementioned finite rates in controlling eruption style and duration, within the context of two types of eruptions at the Soufrière Hills Volcano, Montserrat: Vulcanian and sub-Plinian eruptions. Exsolution, pressure, and velocity relaxation rates all appear to exert important controls on eruption duration. More significantly, however, a single finite exsolution rate characteristic of the Soufrière Hills magma composition is able to produce both end-member eruption durations observed in nature. The duration therefore appears to be largely controlled by the timescales available for exsolution, which depend on dynamic processes such as ascent rate and fragmentation wave speed.
    Description: Published
    Description: 110-139
    Description: 5V. Dinamica dei processi eruttivi e post-eruttivi
    Description: JCR Journal
    Keywords: Magma ascent ; Conduit dynamics ; Soufrière Hills Volcano ; Finite-rate exsolution ; Pressure relaxation ; Velocity relaxation ; 04.08. Volcanology ; Numerical modeling
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 5
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    Inner-shelf ocean dynamics and seafloor morphologic changes during Hurricane Sandy (2017)
    Elsevier
    Details
    Publication Date: 2022-05-25
    Description: This paper is not subject to U.S. copyright. The definitive version was published in Continental Shelf Research 138 (2017): 1-18, doi:10.1016/j.csr.2017.02.003.
    Description: Hurricane Sandy was one of the most destructive hurricanes in US history, making landfall on the New Jersey coast on October 30, 2012. Storm impacts included several barrier island breaches, massive coastal erosion, and flooding. While changes to the subaerial landscape are relatively easily observed, storm-induced changes to the adjacent shoreface and inner continental shelf are more difficult to evaluate. These regions provide a framework for the coastal zone, are important for navigation, aggregate resources, marine ecosystems, and coastal evolution. Here we provide unprecedented perspective regarding regional inner continental shelf sediment dynamics based on both observations and numerical modeling over time scales associated with these types of large storm events. Oceanographic conditions and seafloor morphologic changes are evaluated using both a coupled atmospheric-ocean-wave-sediment numerical modeling system that covered spatial scales ranging from the entire US east coast (1000 s of km) to local domains (10 s of km). Additionally, the modeled response for the region offshore of Fire Island, NY was compared to observational analysis from a series of geologic surveys from that location. The geologic investigations conducted in 2011 and 2014 revealed lateral movement of sedimentary structures of distances up to 450 m and in water depths up to 30 m, and vertical changes in sediment thickness greater than 1 m in some locations. The modeling investigations utilize a system with grid refinement designed to simulate oceanographic conditions with progressively increasing resolutions for the entire US East Coast (5-km grid), the New York Bight (700-m grid), and offshore of Fire Island, NY (100-m grid), allowing larger scale dynamics to drive smaller scale coastal changes. Model results in the New York Bight identify maximum storm surge of up to 3 m, surface currents on the order of 2 ms−1 along the New Jersey coast, waves up to 8 m in height, and bottom stresses exceeding 10 Pa. Flow down the Hudson Shelf Valley is shown to result in convergent sediment transport and deposition along its axis. Modeled sediment redistribution along Fire Island showed erosion across the crests of inner shelf sand ridges and sedimentation in adjacent troughs, consistent with the geologic observations.
    Description: This research was funded by the U.S. Geological Survey (USGS), Coastal and Marine Geology Program, and conducted by the Coastal Change Processes Project. This research was supported in part by the Department of the Interior Hurricane Sandy Recovery program.
    Keywords: Shoreface connected sand ridges ; Sediment transport ; Fire Island, NY ; Hurricane Sandy ; Inner shelf ; Numerical modeling
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 6
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    Development of a coupled wave-flow-vegetation interaction model (2017)
    Elsevier
    Details
    Publication Date: 2022-05-25
    Description: © The Author(s), 2016. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Computers & Geosciences 100 (2017): 76–86, doi:10.1016/j.cageo.2016.12.010.
    Description: Emergent and submerged vegetation can significantly affect coastal hydrodynamics. However, most deterministic numerical models do not take into account their influence on currents, waves, and turbulence. In this paper, we describe the implementation of a wave-flow-vegetation module into a Coupled-Ocean-Atmosphere-Wave-Sediment Transport (COAWST) modeling system that includes a flow model (ROMS) and a wave model (SWAN), and illustrate various interacting processes using an idealized shallow basin application. The flow model has been modified to include plant posture-dependent three-dimensional drag, in-canopy wave-induced streaming, and production of turbulent kinetic energy and enstrophy to parameterize vertical mixing. The coupling framework has been updated to exchange vegetation-related variables between the flow model and the wave model to account for wave energy dissipation due to vegetation. This study i) demonstrates the validity of the plant posture-dependent drag parameterization against field measurements, ii) shows that the model is capable of reproducing the mean and turbulent flow field in the presence of vegetation as compared to various laboratory experiments, iii) provides insight into the flow-vegetation interaction through an analysis of the terms in the momentum balance, iv) describes the influence of a submerged vegetation patch on tidal currents and waves separately and combined, and v) proposes future directions for research and development.
    Description: This study was part of the Estuarine Physical Response to Storms project (GS2-2D), supported by the Department of Interior Hurricane Sandy Recovery program.
    Keywords: Flexible aquatic vegetation ; Coastal hydrodynamics ; Numerical modeling
    Repository Name: Woods Hole Open Access Server
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