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  • 1
    Publication Date: 2022-06-09
    Description: Near-continuous monitoring both of gas emissions (CO2, CH4 and H2S) and of water temperature at Santa Venera al Pozzo thermal springs (SE foot of Mt. Etna volcano, Sicily, Italy) was conducted from December 2017 to April 2019, using a novel and cheaper Chromatography Monitoring System (CMS) coupled with a water temperature sensor. The results showed methane as predominant gas and temporal changes in gas concentrations that were in part due to daily fluctuations, which caused small amplitude variations, and in part due to non-environmental causes. These latter were correlated with the occurrence of strong earthquakes and slow tectonic events related to magmatic intrusions, but not with input of magmatic gases into the thermal aquifer, given the nonmagmatic origin of all monitored gases. Methane spikes were observed during many volcano-tectonic events and call for a deep source of this gas. H2S was detected only during the strongest local tectonic events, including a Mw 4.9 earthquake, suggesting that this gas has a common origin as CH4 (i.e., mixing between microbial and thermogenic gas), but it is released only when tectonic stress is applied for sufficiently long periods as to cause H2S oversaturation in the hydrothermal aquifer. Water temperature decreases were also observed immediately after the two strongest earthquakes in the area, which helped us produce a comprehensive model to explain the observed geochemical variations. Our approach allowed revealing the great sensitivity of gases such as CH4 and especially H2S to tectonic stress, thus making them valuable indicators of impending strong tectonic or volcanotectonic events.
    Description: Published
    Description: 229388
    Description: 9T. Geochimica dei fluidi applicata allo studio e al monitoraggio di aree sismiche
    Description: JCR Journal
    Keywords: Earthquakes ; Volcanic activity ; Geothermal systems ; Fluids ; Tectonics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
    Publication Date: 2022-06-07
    Description: We present the results of an experiment taking place inside the geophysical museum of Rocca di Papa (Rome, Italy), where the high radon levels detected might pose a risk to the health of workers and of the public audience. As a first step towards the mitigation of potential exposure risk, four active sensors were installed at different floors of the building, in order to continuously monitor not only radon exhalation from the soil but also its transport from the ground up to elevated floors. Collecting more than three years of data of radon concentration enables us to identify fluctuations over both short and seasonal scales and to elucidate the relation between radon variations and changes of internal temperature and relative humidity. The analysis of such dataset reveals how the healthiness of indoor environments in terms of radon concentration is controlled by a number of factors, including the environmental conditions and the use of heating and ventilation systems. Finally, the continuous radon monitoring at different levels of the building provides a unique chance to trace the vertical radon diffusion, allowing to make a first-order estimate of upward radon velocity.
    Description: Published
    Description: 106919
    Description: 7A. Geofisica per il monitoraggio ambientale
    Description: JCR Journal
    Keywords: indoor radon, gas diffusion ; 05.01. Computational geophysics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 3
    Publication Date: 2022-06-09
    Description: Young and tectonically active chains like the Central Apennines (Italy) are featured by high structural complexity as a result of the overprint of subsequent deformational stages, making interpretation of seismotectonics challenging. The Central Apennines are characterized by the stacking of tectono-sedimentary units organized in thrust sheets. However, extensional tectonics is currently affecting the axial sector of the thrust belt, mostly expressing in extensional earthquakes. Using a large subsurface dataset acquired for hydrocarbon exploration in the region struck by the 2016–2017 Central Italy seismic sequence, we built a comprehensive 3D geological model and compared it with the seismicity. The model primarily shows a series of thrusts developed during the Miocene-Pliocene Apennines orogenesis and inherited normal faults developed during the Mesozoic extensional phase and the Miocene foreland flexural process. These normal faults were segmented and transported within the thrust sheets, and sometimes they still show a clear surface expression. The succession of tectonic stages resulted in a widespread reactivation of inherited structures, sometimes inverting their kinematics with different styles and rates, and disarticulating pre-existing configurations. Such evolution has a strong impact on the seismicity observed in the area, as demonstrated by some examples that show how the seismicity is aligned on segments of inherited faults, both compressional and extensional. Their reactivation can be explained by their favorable orientation within the current extensional stress field. Results feed the debate about the seismogenic potential of faults identified both at depth and surface, which can impact the seismic hazard of the Apennines.
    Description: Published
    Description: 228861
    Description: 1T. Struttura della Terra
    Description: 2T. Deformazione crostale attiva
    Description: 4T. Sismicità dell'Italia
    Description: JCR Journal
    Keywords: Normal faults ; Thrust sheets ; Inherited faults ; Earthquakes ; Central Apennines ; 3D geological model ; 04.07. Tectonophysics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 4
    Publication Date: 2022-12-01
    Description: An accurate survey of old and new datasets allowed us to probe the nature and role of fluids in the seismogenic processes of the Apennines mountain range in Italy. New datasets include the 1985–2021 instrumented seismicity catalog, the computed seismogenic thickness, and geodetic velocities and strains, whereas data from the literature comprise focal mechanism solutions, CO2 release, Moho depth, tomographic seismic velocities, heat flow and Bouguer gravity anomalies. Most of the inspected datasets highlight differences between the western and eastern domains of the Apennines, while the transition zone is marked by high geodetic strain, prevailing uplift at the surface and high seismic release, and spatially corresponds with the overlapping Tyrrhenian and Adriatic Mohos. Published tomographic models suggest the presence of a large hot asthenospheric mantle wedge which intrudes beneath the western side of the Apennines and disappears at the southern tip of the southern Apennines. This wedge modulates the thermal structure and rheology of the overlying crust as well as the melting of carbonate-rich sediments of the subducting Adriatic lithosphere. As a result, CO2-rich fluids of mantle-origin have been recognized in association with the occurrence of destructive seismic sequences in the Apennines. The stretched western domain of the Apennines is characterized by a broad pattern of emissions from CO2-rich fluids that vanishes beneath the axial belt of the chain, where fluids are instead trapped within crustal overpressurized reservoirs, favoring their involvement in the evolution of destructive seismic sequences in that region. In the Apennines, areas with high mantle He are associated with different degrees of metasomatism of the mantle wedge from north to south. Beneath the chain, the thickness and permeability of the crust control the formation of overpressurized fluid zones at depth and the seismicity is favored by extensional faults that act as high permeability pathways. This multidisciplinary study aims to contribute to our understanding of the fluid-related mechanisms of earthquake preparation, nucleation and evolution encouraging a multiparametric monitoring system of different geophysical and geochemical observables that could lead the creation of a data-constrained and reliable conceptual model of the role of fluids in the preparatory phase of earthquakes in the Apennines.
    Description: The INGV Earthquake Department Strategic Project FURTHER “The role of FlUids in the pReparaTory pHase of EaRthquakes in Southern Apennines”
    Description: Published
    Description: 104236
    Description: 1T. Struttura della Terra
    Description: 2T. Deformazione crostale attiva
    Description: 3T. Fisica dei terremoti e Sorgente Sismica
    Description: 4T. Sismicità dell'Italia
    Description: 9T. Geochimica dei fluidi applicata allo studio e al monitoraggio di aree sismiche
    Description: JCR Journal
    Keywords: CO2 Earth degassing ; Earthquakes ; Mantle wedge ; Subduction ; Apennines ; 04.06. Seismology ; Geochemistry ; 04.03. Geodesy
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 5
    Publication Date: 2023-03-20
    Description: Implicit integration of the viscous term can significantly improve performance in computational fluid dynamics for highly viscous fluids such as lava. We show improvements over our previous proposal for semi-implicit viscous integration in Smoothed Particle Hydrodynamics, extending it to support a wider range of boundary models. Due to the resulting loss of matrix symmetry, a key advancement is a more robust version of the biconjugate gradient stabilized method to solve the linear systems, that is also better suited for parallelization in both shared-memory and distributed-memory systems. The advantages of the new solver are demostrated in applications with both Newtonian and non-Newtonian fluids, covering both the numerical aspect (improved convergence thanks to the possibility to use more accurate boundary model) and the computing aspect (with excellent strong scaling and satisfactory weak scaling).
    Description: Published
    Description: 111413
    Description: 3IT. Calcolo scientifico
    Description: JCR Journal
    Keywords: SPH ; Low Reynods number ; Implicit integration ; BiCGSTAB ; GPU ; 05.01. Computational geophysics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 6
    Publication Date: 2023-02-07
    Description: Fault zone architecture and its internal structural variability play a pivotal role in earthquake mechanics, by controlling, for instance, the nucleation, propagation and arrest of individual seismic ruptures and the evolution in space and time of foreshock and aftershock seismic sequences. Nevertheless, the along-strike architectural variability of crustal-scale seismogenic sources over regional distances is still poorly investigated. Here, we describe the architectural variability of the 〉40-km-long exhumed, seismogenic Bolfin Fault Zone (BFZ) of the intra-arc Atacama Fault System (Northern Chile). The BFZ cuts through plutonic rocks of the Mesozoic Coastal Cordillera and was seismically active at 5–7 km depth and ≤ 300 °C in a fluid-rich environment. The BFZ includes multiple altered fault core strands, consisting of chlorite-rich cataclasites-ultracataclasites and pseudotachylytes, surrounded by chlorite-rich protobreccias to protocataclasites over a zone up to 60-m-thick. These fault rocks are embedded within a low-strain damage zone, up to 150-m-thick, which includes strongly altered volumes of dilatational hydrothermal breccias and clusters of epidote-rich fault-vein networks at the linkage of the BFZ with subsidiary faults. The strong hydrothermal alteration of rocks along both the fault core and the damage zone attests to an extensive percolation of fluids across all the elements of the structural network during the activity of the entire fault zone. In particular, we interpret the epidote-rich fault-vein networks and associated breccias as an exhumed example of upper-crustal fluid-driven earthquake swarms, similar to the presently active intra-arc Liquiñe-Ofqui Fault System (Southern Andean Volcanic Zone, Chile).
    Description: European Research Council Consolidator Grant Project (NOFEAR) No 614705
    Description: Published
    Description: 104745
    Description: 3T. Fisica dei terremoti e Sorgente Sismica
    Description: JCR Journal
    Keywords: Atacama fault system ; Earthquakes ; Fault structure ; Fault zone rocks ; Fluid-driven seismicity ; Seismogenic faults ; 04. Solid Earth
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 7
    Publication Date: 2023-03-07
    Description: In the present paper we introduce a numerical model for the representation of displacement, strain and stress due to single forces embedded in a layered elastic half-space. The code EFGRN/EFCMP (Elastic Forces GReeN functions/Elastic Forces CoMPutation) is able to represent the mechanical effects due to pre-assigned distributions of single forces. Even if internal deformation sources can be described by distributions of equivalent body forces with vanishing resultant and moment, single forces are employed in geophysics to represent hydraulic and/or lithostatic loads, effects of internal density anomalies, and even some kind of seismic events. A distribution of single forces is also used to describe the effects of an inelastic inclusion located inside an elastic medium. In fact, the recent literature shows that poro-elastic and thermo-elastic inclusions can be represented using single forces distributed on their boundaries. EFGRN/EFCMP shares the benefits of rapid and semi-analytical calculation offered by the parent code, EFGRN/EFCMP , which is instead suitable for the representation of extended dislocation sources, as seismic faults. The present code also provides an option for computing the effects of a distribution of single forces embedded in a homogeneous half-space, by using the analytical solutions of Mindlin. Accordingly, EFGRN/EFCMP can be a valid support both for the representation of forward models of deformation sources and for the procedures of inversion of geodetic data in a layered medium. We show some applications of the code and we provide several scripts in MATLAB language which help the user to quickly start using EFGRN/EFCMP
    Description: Published
    Description: 105136
    Description: 2V. Struttura e sistema di alimentazione dei vulcani
    Description: JCR Journal
    Keywords: 04.08. Volcanology ; 05.01. Computational geophysics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 8
    Publication Date: 2024-01-09
    Description: A common practice of seismology is to analyze earthquake occurrence in terms of events catalogues, with the aim to either find useful correlations between internal mechanisms under study and their outcome in the spatial/temporal series of the events or, more directly, to assess some statistical rules from observations. With this approach, catalogues are often searched for some recognizable patterns or behaviors: in this work we present a software tool created to reveal a particular kind of events sequences. The idea follows from the concept of multiplets, a well known events pattern often found in seismic series. A multiplet is defined as a sequence of events, all near in space and time and exhibiting similar magnitudes. The amount of multiplets in seismic series is related, as it is for other clustering mechanisms, to underlying correlations in the physics of the events. The software, built from scratch, scans seismic catalogues in search of events clustered as “multiplets”: this is done through the thorough application of comparison tests whose parameters thresholds are both user defined and semi-automated. The tool is however more “general” in the sense that by varying values of the filtering parameters it can reveal other kind of patterns too. While we think that this tool can be thought as a general purpose space–time series analyzer, we have found it particularly useful when applied to the results of a seismic simulator with the purpose of assessing their adherence with the observed seismicity. It can be used as a sort of metric to quantify the simulation predictions effectiveness in terms of presence of similar multiplets distributions in simulated vs. real catalogues. The software has been entirely developed in the Wolfram Language (Mathematica), a commercial powerful environment for scientific calculus and results report, but the main computational routine has been also ported to python for open-source, copyleft usage.
    Description: Published
    Description: 105496
    Description: OST5 Verso un nuovo Monitoraggio
    Description: JCR Journal
    Keywords: seismic multiple events ; 05.01. Computational geophysics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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