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  • Articles  (2,309,601)
  • Elsevier  (1,310,548)
  • Springer  (926,220)
  • American Association for the Advancement of Science  (72,833)
  • 2010-2014  (1,067,734)
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  • 1
    Publication Date: 2020-10-29
    Description: We present new viscosity measurements for melts spanning a wide range of anhydrous compositions including: rhyolite, trachyte, moldavite, andesite, latite, pantellerite, basalt and basanite. Micropenetration and concentric cylinder viscometry measurements cover a viscosity range of 10−1 to 1012 Pas and a temperature range from 700 to 1650 °C. These new measurements, combined with other published data, provide a high-quality database comprising ∼800 experimental data on 44 well-characterized melt compositions. This database is used to recalibrate the model proposed by Giordano and Dingwell [Giordano, D., Dingwell, D. B., 2003a. Non-Arrhenian multicomponent melt viscosity: a model. Earth Planet. Sci. Lett. 208, 337–349] for predicting the viscosity of natural silicate melts. The present contribution clearly shows that: (1) the viscosity (η)–temperature relationship of natural silicate liquids is very well represented by the VFT equation [log η=A+B/ (T−C)] over the full range of viscosity considered here, (2) the use of a constant high-T limiting value of melt viscosity (e.g., A) is fully consistent with the experimental data, (3) there are 3 different compositional suites (peralkaline, metaluminous and peraluminous) that exhibit different patterns in viscosity, (4) the viscosity of metaluminous liquids is well described by a simple mathematical expression involving the compositional parameter (SM) but the compositional dependence of viscosity for peralkaline and peraluminous melts is not fully controlled by SM. For these extreme compositions we refitted the model using a temperature-dependent parameter based on the excess of alkalies relative to alumina (e.g., AE/SM). The recalibrated model reproduces the entire database to within 5% relative error (e.g., RMSE of 0.45 logunits).
    Description: Published
    Description: 42–56
    Description: reserved
    Keywords: Viscosity ; Model ; Silicate melts ; Metaluminous ; Peraluminous ; Peralkaline ; 04. Solid Earth::04.01. Earth Interior::04.01.05. Rheology ; 04. Solid Earth::04.04. Geology::04.04.05. Mineralogy and petrology ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
    Publication Date: 2020-10-29
    Description: Two sets of cooling experiments were run at atmospheric conditions for two anhydrous starting latitic and trachytic melts: 1) five cooling rates (25, 12.5, 3, 0.5, and 0.125 °C/min) between 1300° and 800 °C, and 2) a 11 0.5 °C/min cooling rate from 1300 °C with quench temperatures at 1200°, 1100°, 1000° and 900 °C. Trachytic run-products are invariably glassy. Nucleation is also suppressed in the latitic run-products at the three highest 13 cooling rates. Conversely, in the 0.5 and 0.125 °C/min runs, latites have a crystal content of 90 vol.%. The 14 phases are: plagioclase, clinopyroxene, glass and iron-bearing oxide (in order of abundance). The variable 15 quench temperatures, investigated by coupling experiments with Pt-wire and Pt- capsule sample containers inset 2,again did not produce crystallization of trachyte, whereas latitic samples are characterized by 10 vol.% of oxides, pyroxenes and plagioclase (in order of appearance), at temperature b1000 °C. Effects of (preferential) heterogeneous nucleation on sample holders, of superheating degree, and chemical species loss during cooling are absent for both melt compositions. The difference of solidification paths between these two silicate melts can be ascribed only to their small chemical differences. In comparison with calculated equilibrium conditions all the experimental latitic and trachytic run-products revealed strong kinetic effects, interpretable in the light of the nucleation theory. The glass- forming ability (GFA) of trachyte is higher, whereas their critical cooling rate (Rc) is lower (b0.125 °C/min), in comparison to latitic melts (RcN0.5 °C/min). The experimental results carried out in this study can be applied to lava flows and domes; trachytic lavas are able to flow for longer period with respect to latitic ones in a metastable condition. Glass-rich terrestrial lavas, i.e. obsidians, can be the result of sluggish nucleation kinetics due to the relative high polymerisation of evolved silicate melts.
    Description: Published
    Description: 91-101
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: crystallization ; lava flows ; 04. Solid Earth::04.08. Volcanology::04.08.02. Experimental volcanism ; 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::04.08.07. Instruments and techniques ; 05. General::05.02. Data dissemination::05.02.02. Seismological data
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  • 3
    Publication Date: 2020-10-29
    Description: The bulk electrical conductivity of the phonotephritic lava from the 1944 eruption of Mt Vesuvius was measured using complex impedance spectroscopy in a multianvil apparatus at 1 GPa and temperatures up to 700 °C. Melting experiments prior to the electrical measurements were also performed on this sample in a piston cylinder apparatus in order to gauge how bulk conductivity varies as a function of its melt fraction. Unlike the behaviour found in basaltic rocks in which conductivity increases with increasing melt fraction, we observe a conductivity decrease of the order of a factor of ten for samples at 700 °C ranging in melt fraction from 32 vol.% to completely molten.We attribute this anomalous behaviour to the progressive loss of highly conductive leucite upon melting. The addition of potassium to the melt phase, however, does not result in an increase of the total alkali concentration due to the melting of other mineral components. We also present an empirical model to predict the electrical conductivity of fully molten silicate liquids as a function of temperature and chemical composition, based on conductivity data for natural silicate liquids found in the literature. The inclusion of compositional terms reduces the error by more than a factor of four with respect to a composition independent, temperature-only parameterization.
    Description: Published
    Description: 192-201
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: JCR Journal
    Description: reserved
    Keywords: Electrical conductivity ; silicate melts ; partial melting ; Mt. Vesuvius ; 01. Atmosphere::01.01. Atmosphere::01.01.07. Volcanic effects
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  • 4
    Publication Date: 2020-11-17
    Description: An efficient procedure is proposed in order to define realistic lower limits of velocity errors of a non-permanent GPS station (NPS), i.e. a station where the antenna is installed and operates for short time periods, typically 10-20 days per year. Moreover, the proposed method is aimed at being independent from the standard GPS data processing. The key is to appropriately subsample the coordinate time series of several continuous GPS stations (CGPSs) situated nearby or inside the considered NPS network, in order to simulate the NPS behavior and to estimate the velocity errors associated with the subsampling procedure. The obtained data are therefore used as lower limits to accept or correct the error estimates provided by standard data processing. The proposed approach is applied to data from the dense non-permanent network in the Central Apennine of Italy based on a sequence of solutions for the overlapping time spans 1999-2003, 1999-2004, 1999-2005 and 1999-2007. Both the original and error-corrected velocity patterns are used to compute the strain rate fields. The comparison between the corresponding results reveals large differences that could lead to divergent interpretations about the kinematics of the study area.
    Description: Published
    Description: 249–261
    Description: 2T. Deformazione crostale attiva
    Description: JCR Journal
    Description: reserved
    Keywords: Non-permanent GPS Stations ; Velocity Field ; Strain Rate ; Survey Optimization; ; Solution Sequence ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations
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  • 5
    Publication Date: 2020-11-19
    Description: We report on structural and anisotropy of magnetic susceptibility (AMS) results from the Upper Miocene sediments of the Amantea basin, located on the Tyrrhenian coast of the Calabrian Arc (Southern Italy). The stratigraphic succession of the basin is organized in three depositional sequences, separated by two major angular unconformities. Detailed geologica1 mapping and structural analysis demonstrate that the stratigraphic evolution of the Amantea basin is strongly controlled by a synsedimentary extensional tectonic regime. Severa1 NNE-SSW-trending norma1 fault arrays with large scatter in inclination values have been interpreted as due to a domino faulting mechanism, consistent with a WNW-ESE stretching direction. AMS data have been obtained for 13 sites, both in the not constrained in age first depositional sequence (3 sites), and in the upper Tortonian-lower Messinian clays from the second depositional sequence (10 sites). Al1 the sites show a strong magnetic foliation parallel to the bedding planes, and a well defined magnetic lineation subparallel to the local bedding dip directions. The magnetic lineations cluster around a WNW-ESE trend and are parallel to the stretching directions inferred by fault-slip analysis and basin architecture. These new data then confirm the possibility to use the magnetic lineation to map the strain trajectory in weakly deformed extensional sedimentary basins. Paleomagnetic data (from previous studies) show that the whole Calabrian block underwent a 15°-20° clockwise rotation probably in the Pleistocene, postdating the extensional tectonic events which controlled the Amantea basin geometry. Therefore we suggest for the Amantea basin an original E-W-oriented stretching direction, which may be considered as the older extensional direction characterizing the Late Miocene evolution of the southern Tyrrhenian Sea domain.
    Description: Published
    Description: 33-49
    Description: JCR Journal
    Description: reserved
    Keywords: magnetic fabric ; extentional tectonics ; Miocene ; Calabrian Arc ; Italy ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism
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  • 6
    Publication Date: 2020-11-26
    Description: During the July^August 2001 eruption of Mt. Etna development of extensional fractures/faults and grabens accompanied magma intrusion and subsequent volcanic activity. During the first days of the eruption, we performed an analysis of attitude, displacement and propagation of fractures and faults exposed on the ground surface in two sites, Torre del Filosofo and Valle del Leone, located along the same fracture system in the region surrounding the Valle del Bove depression on the eastern flank of Mt. Etna. Fractures and faults formed as the consequence of a shallow intruding dyke system that fed the several volcanic centres developed along the fracture system. The investigated sites differ in slope attitude and in geometrical relationships between fractures and slopes. In particular, the fracture system propagated parallel to the gentle slope (67‡ dip) in the Torre del Filosofo area, and perpendicular to the steep slope (V25‡ dip) in the Valle del Leone area. In the Torre del Filosofo area, slight graben subsidence and horizontal extension of the ground surface by about 3 m were recorded. In the Valle del Leone area, extensional faulting forming a larger and deeper graben with horizontal extension of the ground surface by about 10 m was recorded. For the Valle del Leone area, we assessed a downhill dip of 14‡ for the graben master fault at the structural level beneath the graben where the fault dip shallows. These results suggest that dyke intrusion at Mount Etna, and particularly in the region surrounding the Valle del Bove depression, may be at the origin of slope failure and subsequent slumps where boundary conditions, i.e. geometry of dyke, slope dip and initial shear stress, amongst others, favour incipient failures.
    Description: Published
    Description: 281-294
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.2. Tettonica attiva
    Description: 3.5. Geologia e storia dei sistemi vulcanici
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: dykes ; extensional fractures ; grabens ; slope failures ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress ; 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::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
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  • 7
    Publication Date: 2020-11-16
    Description: Active volcanoes characterized by open conduit conditions generate sonic and infrasonic signals, whose investigation provides useful information for both monitoring purposes and studying the dynamics of explosive processes. In this work, we discuss the automatic procedures implemented for a real-time application to the data acquired by a permanent network of five infrasound stations running at Mt. Etna volcano. The infrasound signals at Mt. Etna consist in amplitude transients, called infrasound events. The adopted procedure uses a multi-algorithm approach for event detection, counting, characterization and location. It is designed for an efficient and accurate processing of infrasound records provided by single-site and array stations. Moreover, the source mechanism of these events can be investigated off-line or in near real-time by using three different models: i) Strombolian bubble; ii) resonating conduit and iii) Helmholtz resonator. The infrasound waveforms allow us to choose the most suitable model, to get quantitative information about the source and to follow the time evolution of the source parameters.
    Description: Published
    Description: 1215–1231
    Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio
    Description: JCR Journal
    Description: open
    Keywords: infrasound ; monitoring system ; Mt. Etna ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
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  • 8
    Publication Date: 2020-11-17
    Description: We investigate the P wave velocity structure and the Vp/Vs ratio beneath the Italian peninsula down to 100 and 60 km depth respectively by seismic travel time tomography. We invert data provided by the International Seismological Centre (ISC) (1997–2005), making use of some alternative strategies for the travel time approach in a well constrained and worldwide adopted code (SIMULPS). Resolution for the different layers is discussed and sensitivity analyses are performed through test inversions to explore the resolution characteristics of the model at different spatial scales. The resulting tomographic images provide a detailed sketch of the P wave anomalies, clearly showing, among the other features, the shape of the Ivrea body in the Western Alps, the upwelling of the oceanic crust in the Ligurian Sea and the slab under the Calabrian arc. They are less informative for the Vp/Vs ratio. Nevertheless, some features are very interesting and deserve further investigation like the anomalous decrease of the Vp/Vs ratio under the Ligurian Sea or the variations of the Vp/Vs ratio calculated in the first 10 km depth of the Apenninic region with respect to the lower values of the Alpine region at the same depth. The tomographic cross sections reveal a continuous superposition of two kinds of crusts (transitional over Adriatic) all along the peninsula but do not show any slab, intended as a clear, vertical downgoing high velocity material in either the northern or central Apennines.
    Description: Published
    Description: 1-23
    Description: 4T. Sismicità dell'Italia
    Description: JCR Journal
    Description: reserved
    Keywords: Seismic tomography ; Lithospheric structure ; Vp/Vs ratio ; 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy
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  • 9
    Publication Date: 2020-12-03
    Description: A study of the He isotopic ratios of fluid inclusions in olivine and pyroxene from the Roman Comagmatic Province (RCP),Italy, is presented together with 87Sr/86Sr isotope compositions of the whole rock or pyroxene phenocrysts. A clear covariation in He and Sr isotopes is apparent, with a strong northward increase in radiogenic He and Sr being evident. He and Sr isotopes ratios range from 3He/4He = 5.2 Ra and 87Sr/86Sr = 0.7056 in south Campania, to 3He/4He = 0.44 Ra and 87Sr/86Sr = 0.715905 in the northernmost Latium. Helium isotope ratios are significantly lower than MORB values and are among the lowest yet measured in subduction zone volcanism. The 3He/4He of olivine and pyroxene phenocryst-hosted volatiles appear to be little influenced by posteruptive processes and magma–crust interaction. The 3He/4He–87Sr/86Sr covariation is consistent with binary mixing between an asthenospheric mantle similar to HIMU ocean island basalts, and an enriched (radiogenic) mantle end member generated from subduction of the Ionian/Adriatic plate. The contribution of radiogenic He from metasomatic fluids and postmetasomatism radiogenic ingrowth in the wedge is strongly dependent on the initial He concentration of the mantle. Only when asthenosphere He concentrations are substantially lower than the MORB source mantle, and metasomatism occurred at the beginning of the subduction (f30 Ma), can ingrowth in the mantle wedge account for the 3He/4He of the most radiogenic basalts.
    Description: - European Social Fund - Scottish Universities - Carnegie Trust for the Universities of Scotland.
    Description: Published
    Description: 295–308
    Description: partially_open
    Keywords: Roman Comagmatic Province ; fluid inclusions ; helium ; strontium ; 04. Solid Earth::04.01. Earth Interior::04.01.03. Mantle and Core dynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.06. Subduction related processes ; 04. Solid Earth::04.07. Tectonophysics::04.07.08. Volcanic arcs ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 10
    Publication Date: 2020-12-21
    Description: A sedimentary sequence spanning Marine Isotope Stage (MIS) 6 to MIS 2 in core LC07, recovered in the central Mediterranean, has been investigated in order to produce a high-resolution paleoceanographic reconstruction. The changes in productivity deduced from calcareous plankton relative abundances and independently confirmed by the BaXS fluctuations are linked to the stability of the water column which is mainly controlled by the water mass temperature. During glacial intervals, productivity was generally enhanced. Oligotrophic and warmer water masses with a deepened seasonal thermocline can be inferred for most of MIS5. The magnetic properties of the sediment show increased occurrences of North Africa dust in the central Mediterranean during cold phases, likely as a consequence of a more efficient erosive process triggered by southward displacement of the intertropical convergence zone. Although increases in both productivity and Saharan dust occurred during cold periods, the atmospheric inputs do not seem to contribute significantly to the fertilization of primary producers. A Shannon Index curve has been used to tentatively synthesize the variations of calcareous nannofossil assemblages through the last 150 kyr. The assemblage diversity sharply increased coincident with the transition from the penultimate glacial to the last interglacial, subsequently low diversity was gradually reached again in the last glacial.
    Description: Published
    Description: 26-41
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: reserved
    Keywords: calcareous nannofossils ; foraminifera ; paleoproductivity ; Late Pleistocene ; central mediterranean ; 03. Hydrosphere::03.01. General::03.01.06. Paleoceanography and paleoclimatology ; 04. Solid Earth::04.04. Geology::04.04.08. Sediments: dating, processes, transport ; 04. Solid Earth::04.05. Geomagnetism::04.05.07. Rock magnetism
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  • 11
    Publication Date: 2020-12-21
    Description: The lithological and compositional characteristics of eighteen different pyroclastic deposits of Campanian origin, dated between 125 cal ky BP and 22 cal ky BP, were described. The pyroclastic deposits were correlated among different outcrops mainly located on the Apennine slopes that border the southern Campanian Plain. They were grouped in two main stratigraphic and chronologic intervals of regional significance: a) between Pomici di Base (22.03 cal ky BP; Somma–Vesuvius) and Campanian Ignimbrite (39 cal ky BP; Campi Flegrei) eruptions; and b) older than Campanian Ignimbrite eruption. Three new 14C AMS datings support the proposed correlations. Six eruptions were attributed to the Pomici di Base- Campanian Ignimbrite stratigraphic interval, while twelve eruptions are older than Campanian Ignimbrite. Of the studied deposits two originated from Ischia island, five are related to Campi Flegrei, and three to Somma– Vesuvius. Two eruptions have an uncertain correlation with Somma–Vesuvius or Campi Flegrei, while six eruptions remain of uncertain source. Minimum volumes of five eruptions were assessed, ranging between 0.5 km3 and 4 km3. Two of the studied deposits were correlated with Y-3 and X-5 tephra layers, which are widely dispersed in the central Mediterranean area. The new stratigraphic and chronologic data provide an upgraded chrono-stratigraphy for the explosive activity of Neapolitan volcanoes in the period between 125 and 22 cal ky BP.
    Description: Published
    Description: 19–48
    Description: 3.5. Geologia e storia dei sistemi vulcanici
    Description: JCR Journal
    Description: reserved
    Keywords: Neapolitan volcanoes ; late Pleistocene ; explosive eruptions ; Somma–Vesuvius ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.08. Sediments: dating, processes, transport ; 04. Solid Earth::04.04. Geology::04.04.10. Stratigraphy ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous
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  • 12
    Publication Date: 2020-12-23
    Description: In July 1998, an Mw = 6.2 earthquake struck the islands of Faial, Pico and San Jorge (in the Azores Archipelago), registering VIII on the Modified Mercalli Intensity scale and causing major destruction in the northeastern part of Faial. The main shock was located offshore, 8 km North East of the island, and it triggered a seismic sequence that lasted for several weeks. The existing data for this earthquake include both the general tectonic environment of the region and the teleseismic information. This is accompanied by one strong-motion record obtained 15 km from the epicentre, the epicentre location of aftershocks, and a large collection of the damage inflicted to the building stock (as poor rubble masonry, of 2-3 storeys). The present study was carried out in two steps: first, with a finite-fault stochastic simulation method of ground motion at sites throughout the affected islands, for two possible locations of the rupturing fault and for a large number of combinations of rupture mechanisms (as a parametric analysis); secondly, the damage to buildings was modelled using a well-known macroseismic method that considers the building typologies and their associated vulnerabilities. The main intent was to integrate different data (geological, seismological and building features) to produce a scenario model to reproduce and justify the level of damage generated during the Faial earthquake. Finally, through validation of the results provided by these different approaches, we obtained a complete procedure for the parameters of a first model for the production of seismic damage scenarios for the Azores Islands region.
    Description: Published
    Description: 361–381
    Description: 5T. Sismologia, geofisica e geologia per l'ingegneria sismica
    Description: JCR Journal
    Description: open
    Keywords: Stochastic finite-fault scenarios ; Building damage assessment ; 9th July Faial earthquake ; Azores Islands ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous
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  • 13
    Publication Date: 2020-12-07
    Description: We present a new method for measuring SO2 with the data from the ASTER (Advanced Spaceborne Thermal Emission and Reflectance radiometer) orbital sensor. The method consists of adjusting the SO2 column amount until the ratios of radiance simulated on several ASTER bands match the observations. We present a sensitivity analysis for this method, and two case studies. The sensitivity analysis shows that the selected band ratios depend much less on atmospheric humidity, sulfate aerosols, surface altitude and emissivity than the raw radiances. Measurements with b25% relative precision are achieved, but only when the thermal contrast between the plume and the underlying surface is higher than 10 K. For the case studies we focused on Miyakejima and Etna, two volcanoes where SO2 is measured regularly by COSPEC or scanning DOAS. The SO2 fluxes computed from a series of ten images of Miyakejima over the period 2000–2002 is in agreement with the long term trend of measurement for this volcano. On Etna, we compared SO2 column amounts measured by ASTER with those acquired simultaneously by ground-based automated scanning DOAS. The column amounts compare quite well, providing a more rigorous validation of the method. The SO2 maps retrieved with ASTER can provide quantitative insights into the 2D structure of non-eruptive volcanic plumes, their dispersion and their progressive depletion in SO2.
    Description: R.C. was supported by a grant from F.R.I.A (Fond pour la Recherche Industrielle et Appliquée). GGS acknowledges a PhD grant funded by the project “Sviluppo di sistemi di monitoraggio” funded by Dipartimento di Protezione Civile della Regione Sicilia, INGV (Istituto Nazionale di Geofisica e Vulcanologia, sezione di Catania—Italy) and NOVAC (Network for Observation of Volcanic and Atmospheric Change) EU-funded FP6 project no. 18354. P-F. C. is research associate with FRS-FNRS and benefited from its financial support (F.4511.08).
    Description: Published
    Description: 42-54
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: JCR Journal
    Description: restricted
    Keywords: remote sensing, SO2, ASTER, DOAS, Etna, Miyakejima ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 14
    Publication Date: 2021-01-07
    Description: The CO2 degassing process from a large area on the Tyrrhenian side of central Italy, probably related to the input into the upper crust of mantle fluids, was investigated in detail through the geochemical study of gas emissions and groundwater. Mass-balance calculations and carbon isotopes show that over 50% of the inorganic carbon in regional groundwater is derived from a deep source highlighting gas−liquid separation processes at depth. The deep carbonate−evaporite regional aquifer acts as the main CO2 reservoir and when total pressure of the reservoir fluid exceeds hydrostatic pressure, a free gas phase separates from the parent liquid and escapes toward the surface generating gas emissions which characterise the study area. The distribution of the CO2 flux anomalies and the location of high PCO2 springs and gas emissions suggest that the storage and the expulsion of the CO2 toward the atmosphere are controlled by the geological and structural setting of the shallow crust. The average CO2 flux and the total amount of CO2 discharged by the study area were computed using surface heat flow, enthalpy and CO2 molality of the liquid phase circulating in the deep carbonate−evaporite aquifer. The results show that the CO2 flux varies from 1×104 mol y−1 km−2 to 5×107 mol y−1 km−2, with an average value of 4.8×106 mol y−1 km−2, about five times higher than the value of 1×106 mol y−1 derived by Kerrick et al. [Kerrick, D.M., McKibben, M.A., Seward, T.M., Caldeira, K., 1995. Convective hydrothermal CO2 emission from high heat flow regions. Chem. Geol. 121, 285–293] as baseline for terrestrial CO2 emissions. The total CO2 discharged from the study area is 0.9×1011 mol y−1, confirming that Earth degassing from Tyrrhenian central Italy is a globally relevant carbon source
    Description: Published
    Description: 89–102
    Description: 2.4. TTC - Laboratori di geochimica dei fluidi
    Description: 4.5. Degassamento naturale
    Description: JCR Journal
    Description: reserved
    Keywords: Earth degassing ; carbon dioxide ; CO2 flux ; groundwater ; 04. Solid Earth::04.02. Exploration geophysics::04.02.01. Geochemical exploration ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 15
    Publication Date: 2021-01-07
    Description: The quaternary volcanic complex of Mount Amiata is located in southern Tuscany (Italy) and represents the most recent manifestation of the Tuscan Magmatic Province. The region is characterised by a large thermal anomaly and by the presence of numerous CO2-rich gas emissions and geothermal features, mainly located at the periphery of the volcanic complex. Two geothermal systems are located, at increasing depths, in the carbonate and metamorphic formations beneath the volcanic complex. The shallow volcanic aquifer is separated from the deep geothermal systems by a low permeability unit (Ligurian Unit). A measured CO2 discharge through soils of 1.8 109 mol a 1 shows that large amounts of CO2 move from the deep reservoir to the surface. A large range in d13CTDIC ( 21.07 to +3.65) characterises the waters circulating in the aquifers of the region and the mass and isotopic balance of TDIC allows distinguishing a discharge of 0.3 109 mol a 1 of deeply sourced CO2 in spring waters. The total natural CO2 discharge (2.1 109 mol a 1) is slightly less than minimum CO2 output estimated by an indirect method (2.8 109 mol a 1), but present-day release of 5.8 109 mol a 1 CO2 from deep geothermal wells may have reduced natural CO2 discharge. The heat transported by groundwater, computed considering the increase in temperature from the infiltration area to the discharge from springs, is of the same order of magnitude, or higher, than the regional conductive heat flow (〉200 mWm 2) and reaches extremely high values (up to 2700mWm 2) in the north-eastern part of the study area. Heat transfer occurs mainly by conductive heating in the volcanic aquifer and by uprising gas and vapor along fault zones and in those areas where low permeability cover is lacking. The comparison of CO2 flux, heat flow and geological setting shows that near surface geology and hydrogeological setting play a central role in determining CO2 degassing and heat transfer patterns.
    Description: Published
    Description: 860–875
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: 2.4. TTC - Laboratori di geochimica dei fluidi
    Description: 4.5. Studi sul degassamento naturale e sui gas petroliferi
    Description: JCR Journal
    Description: reserved
    Keywords: Carbon dioxide degassing ; Monte Amiata ; 03. Hydrosphere::03.04. Chemical and biological::03.04.05. Gases ; 03. Hydrosphere::03.04. Chemical and biological::03.04.06. Hydrothermal systems ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 16
    Publication Date: 2021-05-12
    Description: Although the tectonic features and stress regime typical for accretionary complexes and back-arc domains have been widely documented so far, few are known on the transitional zone separating these two systems. Here we report on structural analysis and anisotropy of magnetic susceptibility (AMS) results from Eocene–Pliocene sediments exposed in western Sardinia. From late Oligocene to middle Miocene, the studied area was located between the Alpine–Apennine wedge to the east, which was undergoing shortening and accretion, and the Liguro–Provenc al basin, undergoing extension and spreading. We find that, prior to the formation of the Liguro–Provenc al basin, the middle Eocene–lower Oligocene sediments cropping out at the southwesternmost edge of Sardinia were subjected to NE–SW shortening (in present-day coordinates), in agreement with recently reported geological information. Conversely, the upper Oligocene–Pliocene sedimentary sequences record a different evolutionary stage of extensional processes. Upper Oligocene–middle–upper Burdigalian sediments clearly show a N–S-oriented magnetic lineation that can be related to extensional direction along the prevalent E–W-oriented normal faults. On the other hand, no magnetic lineation has been detected in upper Burdigalian–Serravallian sediments, which mark the end of the first rifting process in Sardinia, which likely coincides with the rift-to-drift transition at the core of the Liguro–Provençal basin. Finally, a NE–SW extension is observed in two Tortonian–Pliocene sites at the northwestern margin of the NNW–SSE-oriented Campidano graben. Our study confirms that AMS may represent a valuable strain-trajectory proxy and significantly help to unravel the characters of temporally superimposed tectonic events.
    Description: Published
    Description: 213-232
    Description: 3.4. Geomagnetismo
    Description: JCR Journal
    Description: reserved
    Keywords: Back-arc basin ; Magnetic anisotropy susceptibility (AMS) ; Sardinia ; Mediterranean area ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 17
    Publication Date: 2021-05-17
    Description: This special issue is dedicated to Yuri Taran's outstanding contributions to gas geochemistry that began in the early 1980s with his work on deuterium and 18O compositions of geothermal waters in the Mutnovsky (Kamchatka) region and continues to this day with work on the Kamchatka volcanic volatile budget, carbon isotopes of hydrocarbons, and new insights into the geochemistry of El Chichón volcano, Chiapas. Yuri has contributed greatly to the field of volcanic gas geochemistry and was the first to recognize the distinct deuterium and oxygen isotopic composition of fumarole condensates from volcanoes in Kamchatka (Taran et al. 1987a). The shift in δD and δ18O to significantly heavier values compared to local meteoric water led Yuri to introduce the term “andesitic water” (Taran et al. 1989a, b) which has since been recognized at subduction zone volcanoes globally. This distinct isotopic composition is evidence that volcanoes release water that ultimately originates as subducted seawater and is recycled through the mantle wedge back to the earth's surface. Yuri's early work on the gas emissions from Kamchatka and Kurile Islands volcanoes also included the development and testing of gas geothermometers (Taran 1986) and investigating hydrothermal alteration using isotopic data (Taran et al. 1987b). His curiosity remained focused on the isotope systematics of volcanic gases discharging from Kamchatka and the Kuriles through the late 1980s and 1990s with publications on the gas compositions of Klyuchevskoi (Taran et al. 1991), Mutnovsky (Taran et al. 1992), Avachinsky and Koryaksky (Taran et al. 1997). Yuri was involved in the discovery of a pure and unique rhenium mineral on Kudryavy volcano (Korzhinsky et al. 1994) and provided one of the most detailed chemical studies of high temperature (up to 950°C) fumaroles to date of any volcano (Taran et al. 1995). His 1995 paper on Kudryavy remains highly cited and provides the highest quality volcanic gas data which also include trace elements from a subduction zone. Such data are crucial when we attempt to interpret lower temperature volcanic gas compositions or calculate rare metal fluxes from volcanoes worldwide. His most recent publication on Kamchatka-Kurile volcanic emissions provides a detailed analysis of the total gas flux from these volcanoes (Taran 2009).
    Description: Published
    Description: 369-371
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: 2.4. TTC - Laboratori di geochimica dei fluidi
    Description: JCR Journal
    Description: reserved
    Keywords: Fluids Geochemistry ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 18
    Publication Date: 2021-05-17
    Description: The problem of ranking and weighting experts' performances when quantitative judgments are being elicited for decision support is considered. A new scoring model, the Expected Relative Frequency model, is presented, based on the closeness between central values provided by the expert and known values used for calibration. Using responses from experts in five different elicitation datasets, a cross-validation technique is used to compare this new approach with the Cooke Classical Model, the Equal Weights model, and individual experts. The analysis is performed using alternative reward schemes designed to capture proficiency either in quantifying uncertainty, or in estimating true central values. Results show that although there is only a limited probability that one approach is consistently better than another, the Cooke Classical Model is generally the most suitable for assessing uncertainties, whereas the new ERF model should be preferred if the goal is central value estimation accuracy.
    Description: Published
    Description: 1292-1310
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: reserved
    Keywords: Expert elicitation ; Expert judgement ; Subjective probability ; Cross-validation ; Cooke Classical Model ; Expected Relative Frequency model ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.08. Sediments: dating, processes, transport ; 05. General::05.01. Computational geophysics::05.01.04. Statistical analysis
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 19
    Publication Date: 2021-05-17
    Description: The Lower Pliocene succession of the Crotone Basin (Calabrian Arc, Southern Italy) is mainly comprised of blue-grey marly clay with good magnetic properties. Here the bio-magnetostratigraphic data indicate a mean sedimentation rate of about 12–15 cm/kyr. Around 3.7–3.6 Ma a major change in the sedimentation regime occurred: the blue-grey hemipelagic marls grade rapidly into silty marls with a significant increase in the terrigenous fraction and with abundant siliceous remains throughout the whole interval. Magnetic properties of these sediments are very poor, but an integrated calcareous plankton biostratigraphy (foraminifera and nannofossils) infers a high average sedimentation rate (about 50–60 cm/kyr). The abrupt onset of this sedimentation regime in the Crotone Basin is contemporaneous with a major unconformity already recognized in the northern sector of the basin, part of amajor reorganization phase in the whole Apenninic–Maghrebid Chain known as “Globorotalia puncticulata event”. Reports of coeval siliceous sediments in other marginal basins of the Apennines (Southern Calabria, Southern and Northern Apennines) suggest that this “siliceous event” might have been regionally extensive, having important palaeoceanographical implications.We infer that the “siliceous event” is characterized by a combined tectonic- and climate-induced change in palaeoceanographic conditions. The tectonic triggering factors may have been linked to two synchronous events in the Tyrrhenian–Apennine system: 1) the shortening event also known as “G. puncticulata event”, and 2) the coeval opening of the Vavilov Basin in the Tyrrhenian Sea which yielded profound influences in terms of physiography and characteristics of the Crotone Basin. The consequent uplift of the Southern Apennines would have increased sediment supply and availability of silica, resulting in eutrophication and enhanced silica preservation. Strong winter mixing and possibly upwelling conditions could have increased primary productivity during heavy isotope stages Gi4, Gi2 and MG8, at the onset of the “siliceous event”. This important event, lasting from ca. 3.6 Ma to ca. 3.2 Ma, would have recorded a peculiar transitional period before further climatic deterioration and more drastic palaeoceanographic changes occurred around 3.1 Ma, leading to cyclic sapropel deposition in the whole of the Mediterranean sea.
    Description: Published
    Description: 398-410
    Description: 1A. Geomagnetismo e Paleomagnetismo
    Description: JCR Journal
    Description: restricted
    Keywords: Biostratigraphy ; Magnetostratigraphy ; Pliocene ; Calabrian Arc ; 04. Solid Earth::04.04. Geology::04.04.08. Sediments: dating, processes, transport ; 04. Solid Earth::04.04. Geology::04.04.10. Stratigraphy ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics
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  • 20
    Publication Date: 2021-04-20
    Description: The spatial clustering of basaltic vents in monogenetic volcanic fields has been used as a proxy for crustal thickness in extensional and back-arc tectonic settings. The basaltic vents have a fractal clustered distribution (self-similar clustering) described by a power-law. The power-law is defined over a range, the size range of the distribution, of values (in this case the vents' separation) delimited by a lower and an upper cut-offs. Here we apply the fractal clustering analysis to the two largest monogenetic volcanic fields of the Trans-Mexican Volcanic Belt (TMVB), a continental arc built on different crustal terranes. The Michoacan–Guanajuato volcanic field (MGVF), located in the central-western TMVB, includes over 1000 vents of late Pliocene to Quaternary age, built on attenuated crust of Mesozoic to Tertiary age. The Sierra de Chichinautzin volcanic field (SCVF), in the central-eastern TMVB, is composed of ~ 220 Late Pleistocene to Holocene vents laying above thicker crust of Precambrian to Tertiary age. Monogenetic vents in both volcanic fields show self-similar clustering with fractal exponent D = 1.67 in the range 1.3–38 km (MGVF) and D = 1.56 in the range 1.5–32 km (SCVF). The upper cut-off (Uco) for the power-law distribution of the MGVF well fits the crustal thickness below the volcanic field as derived from independent geophysical data. The Uco value of SCVF indicates a crust thickness of about 32 km, this value is in agreement with new geophysical data that indicate magma underplating the crust beneath the volcanic field area.
    Description: Published
    Description: 55-64
    Description: 1.10. TTC - Telerilevamento
    Description: 3.2. Tettonica attiva
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: reserved
    Keywords: Volcanic fields ; Tectonic ; Vent distribution ; Crust thickness ; Mexico ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
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  • 21
    Publication Date: 2021-06-15
    Description: Public works in progress in the Campanian plain north of Somma-Vesuvius recently encountered the remains of a prehistoric settlement close to the town of Afragola. Rescue excavations brought to light a Bronze Age village partially destroyed and buried by pyroclastic density currents (PDCs) of the Vesuvian Pomici di Avellino eruption (3.8 14C ka BP) and subsequently sealed by alluvial deposits. Volcanological and rockmagnetic investigations supplemented the excavations. Careful comparison between volcanological and archaeological stratigraphies led to an understanding of the timing of the damage the buildings suffered when they were struck by a series of PDCs. The first engulfed the village, located some 14 km to the north of the inferred vent, and penetrated into the dwellings without causing major damage. The buildings were able to withstand the weak dynamic pressure of the currents and deviate their path, as shown by the magnetic fabric analyses. Some later collapsed under the load of the deposits piled up by successive currents. Stepwise demagnetization of the thermal remanent magnetization (TRM) carried by potsherds embedded in the deposits yields deposition temperatures in the order of 260– 320 °C, fully consistent with those derived from pottery and lithic fragments from other distal and proximal sites. The fairly uniform temperature of the deposits is here ascribed to the lack of pervasive air entrainment into the currents. This, in turn, resulted from the lack of major topographical obstacles along the flat plain. The coupling of structural damage and sedimentological analyses indicates that the currents were not destructive in the Afragola area, but TRM data indicate they were still hot enough to cause death or severe injury to humans and animals. The successful escape of the entire population is apparent from the lack of human remains and from thousands of human footprints on the surface of the deposits left by the first PDCs. People were thus able to walk barefoot across the already emplaced deposits and escape the subsequent PDCs. The rapid cooling of the deposits was probably due to both their thinness and heat dissipation due to condensation of water vapour released in the mixture by magma–water interaction.
    Description: Published
    Description: 408–421
    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: JCR Journal
    Description: reserved
    Keywords: pyroclastic density current ; Bronze Age ; magnetic fabric ; deposition temperature ; 04. Solid Earth::04.04. Geology::04.04.10. Stratigraphy ; 04. Solid Earth::04.05. Geomagnetism::04.05.07. Rock magnetism ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks
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  • 22
    Publication Date: 2021-06-21
    Description: Stratospheric balloons are powerful and affordable tools for a wide spectrum of scientific investigations that are carried out at the stratosphere level. They are less expensive compared to satellite projects and have the capability to lift payloads from a few kilograms to a couple of tons or more, well above the troposphere, for more than a month. Another interesting feature of these balloons, which is not viable in satellites, is the short turnaround time, which enables frequent flights. We introduce the PEGASO (Polar Explorer for Geomagnetism And other Scientific Observations) project, a stratospheric payload designed and developed by the INGV (Istituto Nazionale di Geofisica e Vulcanologia), Rome and La Sapienza University, Rome. The project was sponsored by the PNRA (Progetto Nazionale di Ricerche in Antartide), Italy (Peterzen et al., 2003). This light payload (10 kg) was used by the Italian Space Agency (ASI) and Andoya Rocket Range (ARR) for five different scientific missions. PEGASO carries a 3-component flux-gate magnetometer, uses a solar cell array as the power source and has a GPS location system. The bi-directional telemetry system for data transfer and the remote control system were IRIDIUM based
    Description: INGV, PNRA, ASI, ARR, CNR, La Sapienza
    Description: Published
    Description: Beijing, China
    Description: 1.10. TTC - Telerilevamento
    Description: open
    Keywords: LDB ; Polar areas ; Magnetometer ; Stratosphere ; 05. General::05.04. Instrumentation and techniques of general interest::05.04.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Conference paper
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  • 23
    Publication Date: 2021-06-16
    Description: A stable isotope record from a stalagmite collected from Antro del Corchia cave (Apuan Alps, Central Italy), supported by 17 uranium-series ages, indicates enhanced regional rainfall between ca 8.9 and 7.3 kyr cal. BP at the time of sapropel S1 deposition. Within this phase, the highest rainfall occurred between 7.9 and 7.4 kyr cal. BP. Comparison with different marine and lake records, and in particular with the Soreq Cave record (Israel), suggests substantial in-phase occurrence of enhanced rainfall between the Western and Eastern Mediterranean basins. There is no convincing evidence for major climatic change at the time of the “8.2 kyr event”.
    Description: Published
    Description: 279-286
    Description: 3.8. Geofisica per l'ambiente
    Description: JCR Journal
    Description: reserved
    Keywords: climatic change ; olocene ; sapropel S1 ; stalagmite ; 03. Hydrosphere::03.01. General::03.01.06. Paleoceanography and paleoclimatology
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  • 24
    Publication Date: 2021-07-13
    Description: The aim of this study was to investigate the microbial community thriving at two shallow hydrothermal vents off Panarea Island (Italy). Physico-chemical characteristics of thermal waters were examined in order to establish the effect of the vents on biodiversity of both Bacteria and Archaea. Water and adjacent sediment samples were collected at different times from two vents, characterised by different depth and temperature, and analysed to evaluate total microbial abundances, sulphuroxidising and thermophilic aerobic bacteria. Total microbial abundances were on average of the order of 105 cells ml-1, expressed as picoplanktonic size fraction. Picophytoplanktonic cells accounted for 0.77–3.83% of the total picoplanktonic cells. The contribution of bacterial and archaeal taxa to prokaryotic community diversity was investigated by PCR–DGGE fingerprinting method. The number of bands derived from bacterial DNA was highest in the DGGE profiles of water sample from the warmest and deepest site (site 2). In contrast, archaeal richness was highest in the water of the coldest and shallowest site (site 1). Sulphur-oxidising bacteria were detected by both culture- dependent and -independent methods. The primary production at the shallow hydrothermal system of Panarea is supported by a complex microbial community composed by phototrophs and chemolithotrophs.
    Description: Published
    Description: 199-212
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: hydrothermal vents ; bacteria ; geochemistry ; fluids ; 03. Hydrosphere::03.03. Physical::03.03.01. Air/water/earth interactions
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  • 25
    Publication Date: 2020-09-29
    Description: This chapter summarizes a comparative study of shear-wave velocity models and seismic sources in the Campanian volcanic areas of Vesuvius and Phlegraean Fields. These velocity models were obtained through the nonlinear inversion of surfacewave tomography data, using as a priori constraints the relevant information available in the literature. Local group velocity data were obtained by means of the frequency–time analysis for the time period between 0.3 and 2 s and were combined with the group velocity data for the time period between 10 and 35 s from the regional events located in the Italian peninsula and bordering areas and two station phase velocity data corresponding to the time period between 25 and 100 s. In order to invert Rayleigh wave dispersion curves, we applied the nonlinear inversion method called hedgehog and retrieved average models for the first 30–35km of the lithosphere, with the lower part of the upper mantle being kept fixed on the basis of existing regional models. A feature that is common to the two volcanic areas is a low shear velocity layer which is centered at the depth of about 10 km, while on the outside of the cone and along a path in the northeastern part of the Vesuvius area this layer is absent. This low velocity can be associated with the presence of partial melting and, therefore, may represent a quite diffused crustal magma reservoir which is fed by a deeper one that is regional in character and located in the uppermost mantle. The study of seismic source in terms of the moment tensor is suitable for an investigation of physical processes within a volcano; indeed, its components, double couple, compensated linear vector dipole, and volumetric, can be related to the movements of magma and fluids within the volcanic system. Although for many recent earthquake events the percentage of double couple component is high, our results also show the presence of significant non-double couple components in both volcanic areas.
    Description: Published
    Description: 287-309
    Description: reserved
    Keywords: NONE ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 26
    Publication Date: 2020-10-29
    Description: Viscosity of hydrous trachytes from the Agnano Monte Spina eruption (Phlegrean Fields, Italy) has been determined at 1.0 GPa and temperatures between 1200 and 1400 °C using the falling sphere method in a piston cylinder apparatus. The H2O content in the melts ranged from 0.18 to 5.81 wt.%. These high-temperature hydrous viscosities, along with previous ones determined at low-temperature (anhydrous and hydrous) and at high-temperature (anhydrous), at 1 atm on the same melt composition, represent the only complete viscosity data set available for K-trachyticmelts, frommagmatic to volcanic conditions.Viscosity decreases with increasing temperature andwater content in the melt.At constant temperature, viscosity appears to significantly decreasewhen the first wt.% ofH2Ois added.At H2O content higher than 3 wt.% the effect of temperature on viscosity is slight. Moreover, the deviation from Arrhenian behaviour towards greater “fragility” occurs with increasing water content. We combined low- and high-temperature viscosities (also from literature) and parameterized themby the use of a modified Vogel–Fulcher–Tamman equation, which accommodates the non-Arrhenian temperature dependence ofmelt viscosity.Moreover, in order to explore the extent to which the improved knowledge of Agnano Monte Spina trachyte viscosity may affect simulation of volcanic eruption at Phlegrean Fields, we included our viscosity models in numerical simulations of magma flow and fragmentation along volcanic conduits. These simulations show that the new parameterizations (and hence the new equations) give stronger predictions in the temperature interval relevant for magmatic and eruptive processes.
    Description: Published
    Description: 124-137
    Description: JCR Journal
    Description: reserved
    Keywords: Viscosity ; Trachyte ; Falling sphere method ; Vogel–Fulcher–Tamman equation ; 04. Solid Earth::04.08. Volcanology::04.08.02. Experimental volcanism ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
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  • 27
    Publication Date: 2020-11-17
    Description: Mt. Etna in Sicily (Italy) is one of the best monitored basaltic volcanoes in the world due to the frequent eruptions from its summit and flanks. Routine monitoring carried out by the Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Catania, for surveillance purposes permits following the evolution of volcanic events. In this paper, a description of the ash monitoring system as occurred during the August-December 2006 summit eruption at the Southeast Crater (SEC) is shown. This eruption was characterized by lava flow effusions and vigorous Strombolian activity. Eighteen paroxysmal episodes occurred up to the end of November, forming weak ash plumes accompanied by moderate tephra fallout over Etna’s slopes. During these events, we applied a multidisciplinary approach to promptly monitor the paroxysmal activity and the associated tephra fallout, through analysis from seismic tremor and observation from live-cameras, sampling operations, mapping and analysis of the deposit. During the most significant episodes, we carried out textural and grain-size analysis on tephra samples and evaluated the whole grain-size deposit and the erupted volume, while numerical simulations of tephra dispersal allowed better understanding eruptive dynamics. An example of this methodology is applied to the 16 November episode, during which seismic tremor furnished important constraints on the chronology. This paroxysmal eruption produced light fallout on the north-east sector of the volcano for about ten hours and a number of debris-avalanches over the slopes of the SEC cone. The erupted deposit was composed for the most part of lithic components and characterized by a whole grain-size distribution centered on 2.2 , while its total mass was evaluated 7 x 106 kg. On the whole, such integrated studies help to obtain information on magma fragmentation and eruptive mechanisms, to characterize the explosive styles shown by Etna and finally, to better approach the monitoring of imminent eruptions.
    Description: FIRB Italian project “Sviluppo Nuove Tecnologie per la Protezione e Difesa del Territorio dai Rischi Naturali” funded by Italian Minister of University and Research
    Description: Published
    Description: 123-134
    Description: 5V. Processi eruttivi e post-eruttivi
    Description: JCR Journal
    Description: open
    Keywords: Mt. Etna ; volcanic ash monitoring ; tephra deposit ; 2006 eruption ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
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  • 28
    Publication Date: 2020-11-23
    Description: Abstract: The simultaneous solution of the Planck equation (involving the widely used “dual-band” technique) using two shortwave infrared (SWIR) bands allows for an estimate of the fractional area of the hottest part of an active lava flow (fh), and the background temperature of the cooler crust (Tc). The use of a high spectral and spatial resolution imaging spectrometer with a wide dynamic range of 15 bits (DAIS 7915) in the wavelength range from 0.501 to 12.67 µm resulted in the identification of crustal temperature and fractional areas for an intra-crater hot spot at Mount Etna, Italy. This study indicates the existence of a relationship between these Tc and fh extracted from DAIS and Landsat TM data. When the dual band equation system is performed on a lava flow, a logarithmic distribution is obtained from a plot of the fractional area of the hottest temperature versus the temperature of the cooler crust. An entirely different distribution is obtained over active degassing vents, where increases in Tc occur without any increase in fh. This result indicates that we can use scatter plots of Tc vs. fh to discriminate between different types of volcanic activity, in this case between degassing vents and lava flows, using satellite thermal data.
    Description: Published
    Description: 641–651
    Description: 4V. Processi pre-eruttivi
    Description: JCR Journal
    Description: open
    Keywords: Mount Etna ; remote-sensing ; lava-flow ; degassing vent ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 29
    Publication Date: 2020-11-13
    Description: The main effect of magma-carbonate interaction on magma differentiation is the formation of a silica-undersaturated, alkali-rich residual melt. Such a desilication process was explained as the progressive dissolution of CaCO3 in melt by consumption of SiO2 and MgO to form diopside sensu stricto. Magma chambers emplaced in carbonate substrata, however, are generally associated with magmatic skarns containing clinopyroxene with a high Ca-Tschermak activity in their paragenesis. Data are presented from magma-carbonate interaction experiments, demonstrating that carbonate assimilation is a complex process involving more components than so far assumed. Experimental results show that, during carbonate assimilation, a diopside-hedenbergite-Ca-Tschermak clinopyroxene solid solution is formed and that Ca-Tschermak/diopside and hedenbergite/diopside ratios increase as a function of the progressive carbonate assimilation. Accordingly, carbonate assimilation reaction should be written as follows, taking into account all the involved magmatic components: CaCO3solid+SiO2melt+MgOmelt+FeOmelt+Al2O3melt → (Di-Hd-CaTs)sssolid+CO2fluid The texture of experimental products demonstrates that carbonate assimilation produces three-phases (solid, melt, and fluid) whose main products are: i) diopside-hedenbergite-Ca-Tschermak clinopyroxene solid solution; ii) silica-undersaturated CaO-rich melt; and iii) C-O-H fluid phase. The silica undersaturation of the melt and, more importantly, the occurrence of a CO2-rich fluid phase, must be taken into account as they significantly affect partition coefficients and the redox state of carbonated systems, respectively.
    Description: TRIGS Project “Sixth Framework Programme of the European Commission and to the New and Emerging Science and Technology Pathfinder". Project FIRB MIUR “Development of innovative technologies for the environmental protection from natural events”.
    Description: Published
    Description: 503-514
    Description: 3V. Proprietà chimico-fisiche dei magmi e dei prodotti vulcanici
    Description: JCR Journal
    Description: open
    Keywords: carbonate assimilation ; skarns ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 30
    Publication Date: 2020-11-12
    Description: Fogo volcano is an active central volcano, with a lake filled caldera, in the central part of São Miguel Island, Azores, whose current activity is limited to hydrothermal manifestations such as active fumarolic fields, thermal and CO2 cold springs and soil diffuse degassing areas. It is affected by important active tectonic structures, with high seismic activity and practically continuous micro-seismicity. A recurrent feature from the seismicity observed in volcanic regions is the occurrence of clusters of similar earthquakes, whose origin can be attributed to the repeated action of a similar source mechanism at the same focal area. Doublets/multiplets were identified in this study within a catalogue of small magnitude (usually 〈 3) volcano tectonic events recorded in 2003–2004 by a selection of stations around Fogo volcano. All events have been cross-correlated and pairs whose waveforms exhibited a cross-correlation coefficient equal to or higher than 0.9 were analysed using the coda-wave interferometry technique. Subtle velocity variations found between events highlight a seasonal cycle of the velocity patterns, with lower velocity in winter time and higher velocity during summer months. Those results, together with quantitative differences between the same doublets at different stations, exhibit an excellent correlation with rainfall. A seasonal effect can also be broadly seen in the seismicity occurrence, and some of the swarms recorded over the two year period occur during the wettest season or close to episodes of abundant (above average) rainfall. Moreover, temporal and spatial analysis of several swarms highlighted the lack of any mainshock–aftershock sequence and organized migration of the hypocenters. This is suggestive of a very heterogeneous stress field. Vp/Vs is found to be lower than usually observed in volcanic areas, an occurrence likely related to the presence of steamy fluid associated with the geothermal system. Taken together, these observations suggest that pore pressurisation plays a major role in controlling a considerable part of the recorded seismicity. The geothermal fluids around Fogo massif have been identified as derived from meteoric water, which infiltrates through Fogo Lake and the volcano flanks and flows from south to north on the northern flank. All those elements seem to point to a role played by rainfall in triggering seismicity at São Miguel, possibly through pressure changes at depth in response to surface rain and/or an interaction with the geothermal system.
    Description: Published
    Description: 231-246
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: velocity changes ; rainfall ; volcano seismicity ; triggered seismicity ; Azores archipelago ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 31
    Publication Date: 2020-11-17
    Description: Ground-based thermal infrared surveys can contribute to complete heat budget inventories for fumarole fields. However, variations in atmospheric conditions, plume condensation and mixed-pixel effects can complicate vent area and temperature measurements. Analysis of vent temperature frequency distributions can be used, however, to characterise and quantify thermal regions within a field. We examine this using four thermal infrared thermometer and thermal image surveys of the Vulcano Fossa fumarole field (Italy) during June 2004 and July 2005. These surveys show that regions occupied by low temperature vents are characterised by distributions that are tightly clustered around the mean (i.e., the standard deviation is low), highly peaked (positive kurtosis) and skewed in the low temperature direction (negative skewness). This population is associated with wet fumaroles, where boiling controls maximum temperature to cause a narrow distribution with a mode at 90–100°C. In contrast, high temperature vent regions have distributions that are widely spread about the mean (i.e., the standard deviation is high), relatively flat (negative kurtosis) and skewed in the high temperature direction (positive skewness). In this dry case, fumaroles are water-free so that maximum temperatures are not fixed by boiling. As a result greater temperature variation is possible. We use these results to define two vent types at Vulcano on the basis of their thermal characteristics: (1) concentrated (localized) regions of high temperature vents, and (2) dispersed low temperature vents. These occur within a much larger region of diffuse heat emission across which surfaces are heated by steam condensation, the heat from which causes elevated surface temperatures. For Vulcano's lower fumarole zone, high and low temperature vents occupied total areas of 3 and 6 m2, respectively, and occurred within a larger (430 m2) vent-free zone of diffuse heat emission. For this lower zone, we estimate that 21– 43×103 W of heat was lost by diffuse heat emission. A further 4.5×103 W was lost by radiation from high temperature vents, and 6.5×103 W from low temperature vents. Thus, radiative heat losses from high and low temperature vents within Vulcano's lower fumarole zone respectively account for 10% and 15% of the total heat lost from this zone. This shows that radiation from open vents can account for a non-trivial portion of the total fumarole field heat budget.
    Description: Published
    Description: 441
    Description: 2V. Struttura e sistema di alimentazione dei vulcani
    Description: JCR Journal
    Description: reserved
    Keywords: Fumarole ; Vulcano ; Thermal image ; Infrared thermometer ; Heat flux ; 04. Solid Earth::04.03. Geodesy::04.03.06. Measurements and monitoring
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  • 32
    Publication Date: 2020-11-30
    Description: Mafic phenocrysts from selected products of the last 4 ka volcanic activity at Mt. Vesuvius were investigated for their chemical and O-isotope composition, as a proxy for primary magmas feeding the system. 18O/16O ratios of studied Mg-rich olivines suggest that near-primary shoshonitic to tephritic melts experienced a flux of sedimentary carbonate-derived CO2, representing the early process of magma contamination in the roots of the volcanic structure. Bulk carbonate assimilation (physical digestion) mainly occurred in the shallow crust, strongly influencing magma chamber evolution. On a petrological and geochemical basis the effects of bulk sedimentary carbonate digestion on the chemical composition of the near-primary melts are resolved from those of carbonate-released CO2 fluxed into magma. An important outcome of this process lies in the effect of external CO2 in changing the overall volatile solubility of the magma, enhancing the ability of Vesuvius mafic magmas to rapidly rise and explosively erupt at the surface.
    Description: Published
    Description: 84-95
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: JCR Journal
    Description: reserved
    Keywords: stable-isotope ; magma geochemistry ; CO2-degassing ; Vesuvius ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 33
    Publication Date: 2020-11-26
    Description: The volcano–hydrothermal system of El Chichón volcano, Chiapas, Mexico, is characterized by numerous thermal manifestations including an acid lake, steam vents and boiling springs in the crater and acid and neutral hot springs and steaming ground on the flanks. Previous research on major element chemistry reveals that thermal waters of El Chichón can be divided in two groups: (1) neutral waters discharging in the crater and southern slopes of the volcano with chloride content ranging from 1500 to 2200 mg/l and (2) acid-toneutral waters with Cl up to 12,000 mg/l discharging at the western slopes. Our work supports the concept that each group of waters is derived from a separate aquifer (Aq. 1 and Aq. 2). In this study we apply Sr isotopes, Ca/Sr ratios and REE abundances along with the major and trace element water chemistry in order to discriminate and characterize these two aquifers. Waters derived from Aq. 1 are characterized by 87Sr/86Sr ratios ranging from 0.70407 to 0.70419, while Sr concentrations range from 0.1 to 4 mg/l and Ca/Sr weight ratios from 90 to 180, close to average values for the erupted rocks. Waters derived from Aq. 2 have 87Sr/86Sr between 0.70531 and 0.70542, high Sr concentrations up to 80 mg/l, and Ca/Sr ratio of 17–28. Aquifer 1 is most probably shallow, composed of volcanic rocks and situated beneath the crater, within the volcano edifice. Aquifer 2 may be situated at greater depth in sedimentary rocks and by some way connected to the regional oil-gas field brines. The relative water output (l/s) from both aquifers can be estimated as Aq. 1/Aq. 2– 30. Both aquifers are not distinguishable by their REE patterns. The total concentration of REE, however, strongly depends on the acidity. All neutral waters including high-salinity waters from Aq. 2 have very low total REE concentrations (b0.6 μg/l) and are characterized by a depletion in LREE relative to El Chichón volcanic rock, while acid waters from the crater lake (Aq. 1) and acid AS springs (Aq. 2) have parallel profile with total REE concentration from 9 to 98 μg/l. The highest REE concentration (207 μg/l) is observed in slightly acid shallow cold Ca-SO4 ground waters draining fresh and old pyroclastic deposits rich in magmatic anhydrite. It is suggested that the main mechanism controlling the concentration of REE in waters of El Chichón is the acidity. As low pH results from the shallow oxidation of H2S contained in hydrothermal vapors, REE distribution in thermal waters reflects the dissolution of volcanic rocks close to the surface or lake sediments as is the case for the crater lake.
    Description: -
    Description: Published
    Description: 55-66
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: hydrogeochemistry ; geothermal systems ; Sr isotopes ; REE ; El Chichón Volcano ; 03. Hydrosphere::03.02. Hydrology::03.02.03. Groundwater processes ; 03. Hydrosphere::03.04. Chemical and biological::03.04.03. Chemistry of waters ; 03. Hydrosphere::03.04. Chemical and biological::03.04.05. Gases ; 03. Hydrosphere::03.04. Chemical and biological::03.04.06. Hydrothermal systems ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 34
    Publication Date: 2020-12-15
    Description: Structural observations carried out on the volcanic Island of Pantelleria show that the tectonic setting is dominated by NNE trending normal faults and by NW-striking right-lateral strike-slip faults with normal component of motion controlled by a ≈N 100°E oriented extension. This mode of deformation also controls the development of the eruptive fissures, dykes and eruptive centres along NNE–SSW belts that may thus represent the surface response to crustal cracking with associated magma intrusions. Magmatic intrusions are also responsible for the impressive vertical deformations that affect during the Late Quaternary the south-eastern segment of the island and producing a large dome within the Pantelleria caldera complex. The results of the structural analysis carried out on the Island of Pantelleria also improves the general knowledge on the Late Quaternary tectonics of the entire Sicily Channel. ESE–WNW directed extension, responsible for both the tectonic and volcano-tectonic features of the Pantelleria Island, also characterizes, at a greater scale, the entire channel as shown by available geodetic and seismological data. This mode of extension reactivates the older NW–SE trending fault segments bounding the tectonic troughs of the Channel as right-lateral strike-slip faults and produces new NNE trending pure extensional features (normal faulting and cracking) that preferentially develop at the tip of the major strike-slip fault zones. We thus relate the Late Quaternary volcanism of the Pelagian Block magmatism to dilatational strain on the NNE-striking extensional features that develop on the pre-existing stretched area and propagate throughout the entire continental crust linking the already up-welled mantle with the surface.
    Description: Published
    Description: 75-82
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: JCR Journal
    Description: reserved
    Keywords: Extensional tectonics ; Quaternary ; Volcanism ; Pantelleria Island ; Southern Italy ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology
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  • 35
    Publication Date: 2020-12-15
    Description: The eruptive events of the July–August 2001 and October 2002–January 2003 at Mt. Etna provide new insights for reconstructing the complex geometry of the feeding system and their relationship to regional tectonics. The 2001 eruption took place mainly on the upper southern sector of the volcano. The eruption was preceded by a large earthquake swarm for a few days before its onset and accompanied by ground deformation and fracturing. The development of surface cracking along with the seismic pattern has allowed us to recognize three distinct eruptive systems (the SW–NE, NNW–SSE and N–S systems) which have been simultaneously active. Such eruptive systems are only the upper portions of a complex feeding system that was fed at the same time by two distinct magmas. The SW–NE and NNW–SSE systems, connected with the SE crater conduit, were fed by magma coming from depth, whereas the N–S system served instead as an ascending pathway for an amphibole-bearing magma residing in a shallow reservoir. The eruptive activity started again on October 2002 on the NE Rift Zone, where about 20 eruptive vents were aligned between 2500 and 1900 m a.s.l., and on the southern flank, from the central crater to the Montagnola. The onset of eruptive activity was accompanied by a seismic swarm. As in the 2001 eruptive event, two independent feeding systems formed, characterized by distinct magmas. The SW–NE system controlled the feeding of the Northeast Rift and was accommodated by left-lateral displacement along the WNW–ESE trending Pernicana Fault. The N–S system fed the eruptions on the southern flank. Moreover, the associated crustal deformation triggered seismic reactivation of tectonic structures in the eastern flank of the volcano and offshore. These two last eruptions indicate that at Mt. Etna the ascent of magma, as well as the accommodation of deformation, is strongly dominated by local extensional structures that are connected to a regional tectonic regime.
    Description: Published
    Description: 211-233
    Description: partially_open
    Keywords: extensional tectonics ; volcanic activity ; seismicity ; Sicily ; Mt. Etna ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 36
    Publication Date: 2021-01-14
    Description: The viscosity of shoshonitic melts from Vulcanello Peninsula (Vulcano Island, Italy) is experimentally determined at temperatures between 733 K and 1673 K. The water content of the melts varies from 0.03 to 4.75 wt% H2O. The micropenetration technique is employed at ambient pressure in the high viscosity range (109-1012 Pa·s). Falling sphere(s) experiments are performed at 500 and 2000 MPa in the low viscosity range (100.5-103 Pa·s). Results show a decrease of about 2 orders of magnitude in viscosity if ~ 3 wt% of water is added to the dry melt at 1300 K. At high temperature the viscosity of Vulcanello melts is intermediate between that of andesitic and basaltic melts. In contrast, at low temperatures (≤1050 K), the shoshonitic melt is characterized by a lower viscosity with respect to the two previous melts. Based on our new data set, a calculation model is proposed to predict the viscosity of the shoshonitic melts as a function of temperature and water content. The viscosity data are used to constrain the ascent velocity of shoshonitic magmas from Vulcanello within dikes. Using petrological data (temperature and crystal content of the magma) and volcanological information (geometrical parameters of the eruptive fissure and depth of magma storage), we estimate the time scale for the ascent of magma from the main reservoir to the surface. Results show time scales in the order of hours to few days. We conclude that the rapid ascent of poorly evolved melts from Moho depths should be taken into account for the hazard assessment of Vulcano Island.
    Description: Published
    Description: 89-102
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: JCR Journal
    Description: open
    Keywords: dikes ; ascent velocity ; 04. Solid Earth::04.01. Earth Interior::04.01.05. Rheology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 37
    Publication Date: 2021-01-27
    Description: In this work, the control exerted by the stress axes orientation on the evolution of seismic sequences developing in compressive and extensional regimes is analysed. According to the Anderson fault theory, the vertical stress is the minimum principal stress in compressional tectonic regimes, whereas it is the maximum principal stress in extensional regimes. Using Mohr diagrams and discussing the present knowledge about the distribution of vertical and horizontal stress with depth we show that, in absence of localised fluid overpressure, such changes imply that thrust and normal faults become more unstable at shallower and greater depths, respectively. These opposite mechanical behaviours predict, in a rather isotropic body, easier rupture at shallower level in compressional regimes later propagating downward. On the contrary, a first deep rupture propagating upward is expected in extensional regimes. This is consistent with observations from major earthquakes from different areas in the world. We show that the exceptions to downward migration along thrusts occur along steeply inclined faults and probably imply localised supra-hydrostatic fluid pressures. Moreover, we show that the inversion of the meaning of the lithostatic load has consequences also for the role of topography. High topography, increasing the vertical load, should inhibit earthquake development in compressional environments and should favour it in extensional settings. Although several factors, such as geodynamic processes, local tectonic features and rock rheology, are likely to control earthquake locations, stress distribution and tectonic regime, these model predictions are consistent with seismicity distribution in Italy, central Andes and Himalaya. In these areas, large to medium compressional earthquakes occur at the low elevation borders of compressional mountain belts, whereas large extensional earthquakes occur in correspondence to maximum elevations.
    Description: ASI 2001, Cofin 2001 and GNDT fundings
    Description: Published
    Description: 195-222
    Description: partially_open
    Keywords: Seismicity migration ; thrusts ; normal faults ; aftershocks ; 04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article , article
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  • 38
    Publication Date: 2021-01-14
    Description: The viscosity of an iron-bearing melt with composition similar to Unzen andesite was determined experimentally in the high (109-1010.5 Pa·s) and low (5-1000 Pa·s) viscosity range using a parallel plate viscometer and the falling sphere method, respectively. Falling sphere experiments were carried out in an internally heated argon pressure vessel and in a piston cylinder apparatus at 1323 to 1573 K and 200 to 2000 MPa. Creep experiments were performed in the temperature range of 747 - 845 K at 300 MPa. The water content of the melt varies from nominally dry to 6.2 wt% H2O. The Fe2+/Fetot ratio was determined for each sample in the quenched glass using a colorimetric method. Pressure has minor influence on the viscosity compared with the effect of temperature, water content (main compositional parameter controlling the viscosity) or with the Fe2+/Fetot ratio (especially important at low water content of the melt). Based on our new viscosity data and literature data with measured Fe2+/Fetot ratio we propose a new empirical equation to estimate the viscosity η (in Pa·s) of andesitic melts as a function of temperature T (in K), water content w (in wt%) and Fe2+/Fetot ratio. The derived relationship reproduces the experimental data (87 in total) in the viscosity range from 100.5 to 1013 Pa·s with a 1σ standard deviation of 0.17 log units. However, application of this calculation model is limited to Fe2+/Fetot〉0.3 and to temperatures above Tg. Moreover, in the high viscosity range the variation of viscosity with water content is constrained only by few experimental data and needs verification by additional measurements. The viscosity data are used to interpret mixing processes in the Unzen magma chamber prior to 1991-1995 eruption. We demonstrate that the viscosities of the rhyolite and andesite melts from the two end-member magmas are nearly identical prior and during mixing, enabling efficient magma mixing.
    Description: Published
    Description: 208-217
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: JCR Journal
    Description: open
    Keywords: viscosity ; andesite melt ; dissolved water ; redox state of iron ; Unzen ; magma mixing ; 04. Solid Earth::04.04. Geology::04.04.07. Rock geochemistry
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  • 39
    Publication Date: 2021-01-27
    Description: A variety of atypical plume-like structures and focused upwellings that are not rooted in the lower mantle have recently been discussed, and seismological imaging has shown ubiquitous small-scale convection in the uppermost mantle in regions such as the Mediterranean region, the western US, and around the western Pacific. We argue that the three-dimensional return flow and slab fragmentation associated with complex oceanic subduction trajectories within the upper mantle can generate focused upwellings and that these may play a significant role in regional tectonics. The testable surface expressions of this process are the outsidearc alkaline volcanism, topographic swell, and low-velocity seismic anomalies associated with partial melt. Using three-dimensional, simplified numerical subduction models, we show that focused upwellings can be generated both ahead of the slab in the back-arc region (though ~five times further inward from the trench than arc-volcanism) and around the lateral edges of the slab (in the order of 100 km away from slab edges). Vertical mass transport, and by inference the associated decompression melting, in these regions appears strongly correlated with the interplay between relative trench motion and subduction velocities. The upward flux of material from the depths is expected to be most pronounced during the first phase of slab descent into the upper mantle or during slab fragmentation. We discuss representative case histories from the Pacific and the Mediterranean where we find possible evidence for such slab-related volcanism.
    Description: Published
    Description: 54-68
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: reserved
    Keywords: subduction ; magmatism ; upper mantle convection ; geodynamic modeling ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics
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  • 40
    Publication Date: 2021-05-17
    Description: Transionospheric radio signals may experience fluctuations in their amplitude and phase due to irregularity in the spatial electron density distribution, referred to as scintillation. Ionospheric scintillation is responsible for transionospheric signal degradation that can affect the performance of satellite based navigation systems. Usually, the scintillation activity is measured by means of indices such as the normalised standard deviation of the received intensity S4 and the standard deviation of the received phase r/ typically calculated over 1 min of data. Data from a GPS scintillation monitor based on 50 Hz measurements recorded at Dirigibile Italia Station (Ny-Alesund, Svalbard), in the frame of the ISACCO project (De Franceschi et al., 2006) are used to investigate possible adoption of an alternative parameter for the estimate of phase fluctuations: i.e., the standard deviation of the phase rate of change S/. This parameter is shown to better correlate with S4 being much less detrending dependent than r/. The couple (S4, S/) should be then considered a more physical proxy of radio scintillation than the couple (S4, r/).
    Description: Published
    Description: 2188–2193
    Description: 1.7. Osservazioni di alta e media atmosfera
    Description: 3.9. Fisica della magnetosfera, ionosfera e meteorologia spaziale
    Description: JCR Journal
    Description: restricted
    Keywords: Scintillation ; GPS monitors ; Auroral latitudes ; 01. Atmosphere::01.02. Ionosphere::01.02.04. Plasma Physics ; 01. Atmosphere::01.02. Ionosphere::01.02.07. Scintillations ; 05. General::05.01. Computational geophysics::05.01.03. Inverse methods
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  • 41
    Publication Date: 2021-05-17
    Description: Biostratigraphy based on calcareous nannofossils, integrated by magnetostratigraphic, geochronological and isotopic data, allowed establishing a precise chronological framework for the Pleistocene succession within the south-western sector of the Crotone Basin (Calabria, Southern Italy), where the Pliocenee Pleistocene global stratotype section and point is defined, thus demonstrating that sedimentation was quasi-continuous during most of the Lower and Middle Pleistocene. At a large scale, the Pleistocene succession in this sector of the Crotone Basin is characterized by an evident shallowing-upwards trend, showing facies changes from bathyal to shelfal to littoral/continental. However, comparison between adjacent sectors within the investigated area demonstrates that stratigraphic architectures change vastly on very short distances. Our chronological constraints indicate that such changes in sedimentation styles probably occurred in response to differential subsidence rates, which originated tectonically-controlled synsedimentary structures where accommodation space and sediment yield were allotted unevenly. This articulated physiography led to striking differences in the overall thicknesses and organization of Pleistocene stratigraphies and, eventually, to a distinct diachroneity in the first appearance of shallow-marine deposits. In addition, superimposed are complex interplays between regional and local tectonics, eustasy and orbitally-forced climate changes. These interactions have been highlighted by the oxygen isotope stratigraphy established for a part of the studied succession, which is likely to document almost continuously the interval from Marine Isotope Stage (MIS) 26 to MIS 17. In its younger part (post-MIS 17), chronological ties are poor, as the succession is dominated by shallow-water to continental deposits showing a prominent organization into cyclothems. Nevertheless, based on the chronology of the underlying units, it is feasible that basin infill ended during MIS 15-MIS 14 times.
    Description: Published
    Description: 1185-1200
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: restricted
    Keywords: Pleistocene ; Chronostratigraphy ; Southern Italy ; 04. Solid Earth::04.04. Geology::04.04.08. Sediments: dating, processes, transport ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism
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  • 42
    Publication Date: 2021-05-17
    Description: During AprileMay 2010 volcanic ash clouds from the Icelandic Eyjafjallajökull volcano reached Europe causing an unprecedented disruption of the EUR/NAT region airspace. Civil aviation authorities banned all flight operations because of the threat posed by volcanic ash to modern turbine aircraft. New quantitative airborne ash mass concentration thresholds, still under discussion, were adopted for discerning regions contaminated by ash. This has implications for ash dispersal models routinely used to forecast the evolution of ash clouds. In this new context, quantitative model validation and assessment of the accuracies of current state-of-the-art models is of paramount importance. The passage of volcanic ash clouds over central Europe, a territory hosting a dense network of meteorological and air quality observatories, generated a quantity of observations unusual for volcanic clouds. From the ground, the cloud was observed by aerosol lidars, lidar ceilometers, sun photometers, other remote-sensing instruments and in-situ collectors. From the air, sondes and multiple aircraft measurements also took extremely valuable in-situ and remote-sensing measurements. These measurements constitute an excellent database for model validation. Here we validate the FALL3D ash dispersal model by comparing model results with ground and airplane-based measurements obtained during the initial 14e23 April 2010 Eyjafjallajökull explosive phase. We run the model at high spatial resolution using as input hourlyaveraged observed heights of the eruption column and the total grain size distribution reconstructed from field observations. Model results are then compared against remote ground-based and in-situ aircraft-based measurements, including lidar ceilometers from the German Meteorological Service, aerosol lidars and sun photometers from EARLINET and AERONET networks, and flight missions of the German DLR Falcon aircraft. We find good quantitative agreement, with an error similar to the spread in the observations (however depending on the method used to estimate mass eruption rate) for both airborne and ground mass concentration. Such verification results help us understand and constrain the accuracy and reliability of ash transport models and it is of enormous relevance for designing future operational mitigation strategies at Volcanic Ash Advisory Centers.
    Description: Published
    Description: 165-183
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: restricted
    Keywords: Volcanic ash dispersion ; Numerical model ; Model validation ; 2010 Eyjafjallajökull eruption ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous
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  • 43
    Publication Date: 2021-04-07
    Description: During volcanic eruptions, volcanic ash transport and dispersion models (VATDs) are used to forecast the location and movement of ash clouds over hours to days in order to define hazards to aircraft and to communities downwind. Those models use input parameters, called “eruption source parameters”, such as plume height H, mass eruption rate Ṁ, duration D, and the mass fraction m63 of erupted debris finer than about 4 or 63 μm, which can remain in the cloud for many hours or days. Observational constraints on the value of such parameters are frequently unavailable in the first minutes or hours after an eruption is detected. Moreover, observed plume height may change during an eruption, requiring rapid assignment of new parameters. This paper reports on a group effort to improve the accuracy of source parameters used by VATDs in the early hours of an eruption. We do so by first compiling a list of eruptions for which these parameters are well constrained, and then using these data to review and update previously studied parameter relationships. We find that the existing scatter in plots of H versus Ṁ yields an uncertainty within the 50% confidence interval of plus or minus a factor of four in eruption rate for a given plume height. This scatter is not clearly attributable to biases in measurement techniques or to well-recognized processes such as elutriation from pyroclastic flows. Sparse data on total grain-size distribution suggest that the mass fraction of fine debris m63 could vary by nearly two orders of magnitude between small basaltic eruptions ( 0.01) and large silicic ones (〉 0.5). We classify eleven eruption types; four types each for different sizes of silicic and mafic eruptions; submarine eruptions; “brief” or Vulcanian eruptions; and eruptions that generate co-ignimbrite or co-pyroclastic flow plumes. For each eruption type we assign source parameters. We then assign a characteristic eruption type to each of the world's 1500 Holocene volcanoes. These eruption types and associated parameters can be used for ash-cloud modeling in the event of an eruption, when no observational constraints on these parameters are available.
    Description: Published
    Description: 10-21
    Description: 3.6. Fisica del vulcanismo
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: reserved
    Keywords: volcanic eruption ; aircraft ; volcanic plumes ; ash clouds ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
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  • 44
    Publication Date: 2021-06-15
    Description: No eruption, no caldera collapse, and no landslide can take place in a volcano unless its state of stress is suitable for the associated type of rock failure. The state of stress, in turn, results in deformation, and both stress and deformation depend on the mechanical properties of the rocks that constitute the volcano. Understanding stress and deformation in volcanoes is thus of fundamental importance for understanding unrest periods and for accurate forecasting volcano failure, such as may result in large-scale lateral and vertical collapses and eruptions.
    Description: Published
    Description: 1-3
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: JCR Journal
    Description: reserved
    Keywords: stress, deformation, volcano tectonics, physical propertie of volcanic rocks ; 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
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  • 45
    Publication Date: 2021-06-07
    Description: Global Navigation Satellite Systems (GNSS), in particular the Global Positioning System (GPS), have been widely used for high accuracy geodetic positioning. The Least Squares functional models related to the GNSS observables have been more extensively studied than the corresponding stochastic models, given that the development of the latter is significantly more complex. As a result, a simplified stochastic model is often used in GNSS positioning, which assumes that all the GNSS observables are statistically independent and of the same quality, i.e. a similar variance is assigned indiscriminately to all of the measurements. However, the definition of the stochastic model may be approached from a more detailed perspective, considering specific effects affecting each observable individually, as for example the effects of ionospheric scintillation. These effects relate to phase and amplitude fluctuations in the satellites signals that occur due to diffraction on electron density irregularities in the ionosphere and are particularly relevant at equatorial and high latitude regions, especially during periods of high solar activity. As a consequence, degraded measurement quality and poorer positioning accuracy may result. This paper takes advantage of the availability of specially designed GNSS receivers that provide parameters indicating the level of phase and amplitude scintillation on the signals, which therefore can be used to mitigate these effects through suitable improvements in the least squares stochastic model. The stochastic model considering ionospheric scintillation effects has been implemented following the approach described in Aquino et al. (2009), which is based on the computation of weights derived from the scintillation sensitive receiver tacking models of Conker et al. (2003). The methodology and algorithms to account for these effects in the stochastic model are described and results of experiments where GPS data were processed in both a relative and a point positioning mode are presented and discussed. Two programs have been developed to enable the analyses: GPSeq (currently under development at the FCT/UNESP Sao Paulo State University – Brazil) and PP_Sc (developed in a collaborative project between FCT/UNESP and Nottingham University – UK). The point positioning approach is based on an epoch by epoch solution, whereas the relative positioning on an accumulated solution using a Kalman Filter and the LAMBDA method to solve the Double Differences ambiguities. Additionally to the use of an improved stochastic model, all data processing in this paper were performed using an option implemented in both programs, to estimate, for each observable, an individual ionospheric parameter modelled as a stochastic process, using either the white noise or the random walk correlation models. Data from a network of GPS Ionospheric Scintillation and TEC Monitor (GISTM) receivers set up in Northern Europe as part of the ISACCO project (De Franceschi et al., 2006) were used in the experiments. The point positioning results have shown improvements of the order of 45% in height accuracy when the proposed stochastic model is applied. In the static relative positioning, improvements of the order of 50%, also in height accuracy, have been reached under moderate to strong scintillation conditions. These and further results are discussed in this paper.
    Description: Published
    Description: 1113 - 1121
    Description: 3.9. Fisica della magnetosfera, ionosfera e meteorologia spaziale
    Description: 5.4. Banche dati di geomagnetismo, aeronomia, clima e ambiente
    Description: JCR Journal
    Description: restricted
    Keywords: GNSS ; GPS ; Ionospheric scintillation ; Receiver tracking models ; Stochastic model ; Relative and point positioning ; 01. Atmosphere::01.02. Ionosphere::01.02.05. Wave propagation ; 01. Atmosphere::01.02. Ionosphere::01.02.07. Scintillations ; 04. Solid Earth::04.03. Geodesy::04.03.08. Theory and Models
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  • 46
    Publication Date: 2021-06-25
    Description: A multi-model set of atmospheric simulations forced by historical sea surface temperature (SST) or SSTs plus Greenhouse gases and aerosol forcing agents for the period of 1950–1999 is studied to identify and understand which components of the Asian–Australian monsoon (A–AM) variability are forced and reproducible. The analysis focuses on the summertime monsoon circulations, comparing model results against the observations. The priority of different components of the A–AM circulations in terms of reproducibility is evaluated. Among the subsystems of the wide A–AM, the South Asian monsoon and the Australian monsoon circulations are better reproduced than the others, indicating they are forced and well modeled. The primary driving mechanism comes from the tropical Pacific. The western North Pacific monsoon circulation is also forced and well modeled except with a slightly lower reproducibility due to its delayed response to the eastern tropical Pacific forcing. The simultaneous driving comes from the western Pacific surrounding the maritime continent region. The Indian monsoon circulation has a moderate reproducibility, partly due to its weakened connection to June–July–August SSTs in the equatorial eastern Pacific in recent decades. Among the A–AM subsystems, the East Asian summer monsoon has the lowest reproducibility and is poorly modeled. This is mainly due to the failure of specifying historical SST in capturing the zonal land-sea thermal contrast change across the East Asia. The prescribed tropical Indian Ocean SST changes partly reproduce the meridional wind change over East Asia in several models. For all the A–AM subsystem circulation indices, generally the MME is always the best except for the Indian monsoon and East Asian monsoon circulation indices.
    Description: Published
    Description: 1051-1068
    Description: 3.7. Dinamica del clima e dell'oceano
    Description: JCR Journal
    Description: open
    Keywords: CLIVAR C20C ; Asian-Australian monsoon circulation ; AGCM ; Reproducibility ; 01. Atmosphere::01.01. Atmosphere::01.01.02. Climate
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  • 47
    Publication Date: 2021-06-25
    Description: We present the first helium isotope data for thermal waters and gas emissions on the islands of Terceira, Graciosa, Faial, Pico and Flores, as well as new data for Sao Miguel. The results allow us to track current mantle degassing associated with the Azores hot spot, to delineate its spatial distribution and to discuss its possible origin. As a general rule, we find that free gases tend to display somewhat higher 3He/4He ratio than groundwaters.We argue that this difference is likely due to radiogenic helium inputs to aquifers duringwater– rock interactions and, therefore, that gas phases are the fluid carriers with the most representative of mantle source signature. The measured 3He/4He ratios (normalized to the air ratio, Ra) range from lower-than-MORB values (5.23–6.07 Ra) on central Sao Miguel, to MORB values on Faial (8.53 Ra) and Flores (8.04 Ra) – located on either side of the Mid-Atlantic Ridge – and to plume-type values on Graciosa (11.2 Ra) and Terceira (13.5 Ra) where free gases also display ten times higher-than-MORB CO2/3He ratios (1.8–2.6×1010). Such a wide He isotopic range and its spatial distribution corroborate with available data for volcanic rocks, indicating that plume's head presently underlies the central part of the archipelago. The plume-type 3He/4He ratios on Terceira and Graciosa agree with geochemical and seismic evidence of a deep-rooted mantle plume feeding the Azores hot spot. Our finding that high 3He/4He ratios correspond to low 3He concentrations and high (arctype) CO2/3He values exclude a simple plume supply of 3He-rich primitive mantle. Instead, the simultaneity of both elevated CO2/3He and 3He/4He ratios is best explained by a 3He-rich contribution from the lower mantle diluted in a CO2-rich feeding plume that contains a recycled altered oceanic plate component. The alternative possibility of an enhanced time-integrated 3He/(U+Th) ratio in the Azores plume due to a greater compatibility of helium relative to U and Th during melting events is difficult to reconcile with the enriched pattern of volcanic rocks from the central islands. In any case, the Azores plume should derive from a mantle reservoir that could escape convective homogenization for a very long period of time, in agreement with subchondritic osmium isotopic ratios in volcanic rocks from the central islands of the archipelago.
    Description: Published
    Description: 70−80
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: hydrothemal fluids ; helium isotopes ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry
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  • 48
    Publication Date: 2021-06-21
    Description: This paper introduces REXELite, an internet version of REXEL, a software for automatic selection of ground motion suites for nonlinear dynamic analysis of structures. REXELite was developed with the aim of integrating an advanced earthquake records’ repository, such as the ITalianACcelerometricArchive (ITACA), with a tool to define seismic input for engineering seismic analysis according to international standards (with priority to Europe). In fact, REXELite allows to define target design spectra according either to Eurocode 8 or to the Italian building code, and to search ITACA for suitable sets of seven records (comprised of one or two horizontal ground motion components) matching such target spectra: on average, in a user-specified period range, and with the desired tolerance. The records in the set also have, individually and according to some criteria, the most similar spectral shape with respect to that of the code. Selection options include magnitude, source-to-site distance, soil conditions and, if desired, linear scaling of records to reduce further record-to-record variability of the selected suite.This paper introduces REXELite, an internet version of REXEL, a software for automatic selection of ground motion suites for nonlinear dynamic analysis of structures. REXELite was developed with the aim of integrating an advanced earthquake records’ repository, such as the ITalianACcelerometricArchive (ITACA), with a tool to define seismic input for engineering seismic analysis according to international standards (with priority to Europe). In fact, REXELite allows to define target design spectra according either to Eurocode 8 or to the Italian building code, and to search ITACA for suitable sets of seven records (comprised of one or two horizontal ground motion components) matching such target spectra: on average, in a user-specified period range, and with the desired tolerance. The records in the set also have, individually and according to some criteria, the most similar spectral shape with respect to that of the code. Selection options include magnitude, source-to-site distance, soil conditions and, if desired, linear scaling of records to reduce further record-to-record variability of the selected suite.
    Description: Published
    Description: 1761-1778
    Description: 4.1. Metodologie sismologiche per l'ingegneria sismica
    Description: JCR Journal
    Description: reserved
    Keywords: Response spectrum matching ; ITACA ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk
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  • 49
    Publication Date: 2021-07-14
    Description: Field geological data of the Pantelleria Island, a large Late Quaternary volcano located in the Sicily Channel rift zone, integrated with offshore geophysical information, are used to derive the structural setting of the Island and the surrounding region, and to analyse the relationships between tectonics and magmatism. Field work shows that the principal faults exposed on the Island fall into two systems trending NNE–SSW and NW–SE. Mapped faults from offshore multichannel seismic profiles show similar trends, and some of them represent the offshore extension of the Pantelleria Island structures. The NW–SE faults bound the Pantelleria Graben, one of the three main depressions formed since the Late Miocene–Early Pliocene within the African continental platform, which compose the Sicily Channel rift zone. A 3-D Moho depth geometry, derived from inversion of Bouguer gravity data, shows a significant uplift of the discontinuity up to 16–17 km beneath the westernmost part of the Pantelleria Graben and beneath the Pantelleria Island; it lows rapidly to 24–25 km away from the graben northeastward and south-westward. The Moho uplift could explain the presence of a shallow magma chamber in the southern part of the Island, where processes of magmatic differentiation are documented. Geological and geophysical data suggest that the northwestern part of the Sicily Channel is presently dominated by a roughly E–W directed extensional regime. Crustal cracking feeding the Quaternary volcanism could be also related to this extensional field that would be further responsible for the development of the N–S trending volcanic belt that extends in the Sicily Channel from Lampedusa Island to the Graham Bank. This mode of deformation is confirmed also by geodetic data. This implies that in the northwestern part of the Sicily Channel, the E–W extension replaced the NE–SW crustal stretching that originated the NW-trending tectonic depressions constituting the rift zone. © 2008 Elsevier B.V. All rights reserved.
    Description: Published
    Description: 32-46
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: reserved
    Keywords: Pantelleria Island ; Channel rift zone ; structural analysis ; Quaternary volcanism ; gravity modelling ; tectonic extension ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology
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  • 50
    Publication Date: 2021-07-14
    Description: A quantitative analysis of planktonic foraminifera, coupled with petrophysical and paleomagnetic measurements and 14C AMS calibrations, was carried out on a deep core recovered in the Sardinia Channel (Western Mediterranean Sea), during the CIESM Sub2 survey, providing an integrated stratigraphic time-framework over the last 80 kyr. Significant changes in the quantitative distribution of planktonic foraminifera allowed the identification of several eco-bioevents useful to accurately mark the boundaries of the eco-biozones widely recognised in the Western Mediterranean records and used for large scale correlations. Namely, 10 eco-biozones were identified based on the relative abundance of selected climate sensitive planktonic foraminiferal species. Sixteen codified eco-bioevents were correlated with the Alboran Sea planktonic foraminiferal data and four climatic global events (Sapropel S1, Younger Dryas, Greenland Isotope Interstadial 1, Greenland Isotope Stadial 2, Heinrich event H1-H6) were recognized. The eco-bioevents together with the 14C AMS calibrations allowed us to define an accurate age model, spanning between 2 and 83 kyr. The reliability of the age model was confirmed by comparing the colour reflectance (550 nm%) data of the studied record with the astronomically tuned record from the Ionian sea (ODP-Site 964). A mean sedimentation rate of about 7 cm/kyr included three turbidite event beds that were chronologically constrained within the relative low stand and lowering sea level phases of the MIS 4 and 3. The deep-sea sedimentary record includes a distinct tephra occurring at the base of the core which dates 78 ka cal. BP. The paleomagnetic data provide a well-defined record of the characteristic remanent magnetization that may be used to reconstruct the geomagnetic paleosecular variation for the Mediterranean back to 83 kyr.
    Description: Published
    Description: 725 - 737
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: reserved
    Keywords: Integrated stratigraphy ; Late Neogene marine record ; Eco-bio-events ; Reflectance 550 nm % ; Sardinia Channel ; Western Mediterranean ; 04. Solid Earth::04.04. Geology::04.04.04. Marine geology ; 04. Solid Earth::04.04. Geology::04.04.08. Sediments: dating, processes, transport ; 04. Solid Earth::04.04. Geology::04.04.10. Stratigraphy ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism
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  • 51
    Publication Date: 2020-10-29
    Description: We have performed a parametric study on the dynamics of trachytic (alkaline) versus rhyolitic (calc-alkaline) eruptions by employing a steady, isothermal, multiphase non-equilibrium model of conduit flow and fragmentation. The employed compositions correspond to a typical rhyolite and to trachytic liquids from Phlegrean Fields eruptions, for which detailed viscosity measurements have been performed. The investigated conditions include conduit diameters in the range 30–90 m and total water contents from 2 to 6 wt%, corresponding to mass flow rates in the range 106–108 kg/s. The numerical results show that rhyolites fragment deep in the conduit and at a gas volume fraction ranging from 0.64 to 0.76, while for trachytes fragmentation is found to occur at much shallower levels and higher vesicularities (0.81–0.85). An unexpected result is that low-viscosity trachytes can be associated with lower mass flow rates with respect to more viscous rhyolites. This is due to the non-linear combined effects of viscosity and water solubility affecting the whole eruption dynamics. The lower viscosity of trachytes, together with higher water solubility, results in delayed fragmentation, or in a longer bubbly flow region within the conduit where viscous forces are dominant. Therefore, the total dissipation due to viscous forces can be higher for the less viscous trachytic magma, depending on the specific conditions and trachytic composition employed. The fragmentation conditions determined through the simulations agree with measured vesicularities in natural pumice clasts of both magma compositions. In fact, vesicularities average 0.80 in pumice from alkaline eruptions at Phlegrean Fields, while they tend to be lower in most calc-alkaline pumices. The results of numerical simulations suggest that higher vesicularities in alkaline products are related to delayed fragmentation of magmas with this composition. Despite large differences in the distribution of flow variables which occur in the deep conduit region and at fragmentation, the flow dynamics of rhyolites and trachytes in the upper conduit and at the vent can be very similar, at equal conduit size and total water content. This is consistent with similar phenomenologies of eruptions associated with the two magma types.
    Description: Published
    Description: 93-108
    Description: partially_open
    Keywords: trachytic magma ; conduit flow ; eruption dynamics and numerical simulations ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
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  • 52
    Publication Date: 2020-10-13
    Description: Deformation sources in volcanic areas are generally modeled in terms of pressurized tri-axial ellipsoids or pressurized cracks with simple geometrical shapes, embedded in a homogeneous half-space. However, the assumption of a particular source mechanism and the neglect of medium heterogeneities bias significantly the estimate of source parameters. A more general approach describes the deformation source in terms of a suitable moment tensor. Ratios between moment tensor eigenvalues are shown to provide a strong diagnostic tool for the physical interpretation of the deformation source and medium heterogeneities may be accounted for through 3D finite element computations. Leveling and EDM data, collected during the 1982–84 unrest episode at Campi Flegrei (Italy), are employed to retrieve the complete moment tensor according to a Bayesian inversion procedure, considering the heterogeneous elastic structure of the volcanic area. Best fitting moment tensors are found to be incompatible with any pressurized ellipsoid or crack. Taking into account the deflation of a deeper magma reservoir, which accompanies the inflation of a shallower source, data fit improves considerably but the retrieved moment tensor of the shallow source is found to be incompatible with pressurized ellipsoids, still. Looking for alternative physical models of the dislocation source, we find that the best fit moment tensor can be best interpreted in terms of a mixed mode (shear and tensile) dislocation at 5.5 km depth, striking EW and dipping by ~25°–30° to the North. Gravity changes are found to be compatible with the intrusion of ~60–70·10^6 m^3 of volatile rich magma with density ~2400 kg/m^3.
    Description: Published
    Description: 175-185
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: volcanic source ; unrest ; finite element ; inverse theory ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 53
    Publication Date: 2020-11-16
    Description: A 1-D velocity model for the Marche region (central Italy) was computed by inverting P- and S-wave arrival times of local earthquakes. A total of 160 seismic events with a minimum of ten observations, a travel time residual ≤ 0.8 s and an azimuthal gap lower than 180° have been selected. This “minimum 1-D velocity model” is complemented by station corrections, which can be used to take into account possible near-surface velocity heterogeneities beneath each station. Using this new P-wave velocity model and the program HYPOELLIPSE (Lahr, 1999), the selected local events were relocated. Earthquake locations in this study are of higher quality with respect to the original ones. The obtained minimum 1-D velocity model can be used to improve the routine earthquakes locations and represents a further step towards more detailed seismotectonic studies of the area.
    Description: Published
    Description: 1115–1121
    Description: 3T. Sorgente sismica
    Description: JCR Journal
    Description: reserved
    Keywords: Minimum 1D model ; Earthquake locations ; Marche region ; 04. Solid Earth::04.02. Exploration geophysics::04.02.06. Seismic methods
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  • 54
    Publication Date: 2020-11-16
    Description: The MAGFLOW cellular automata model was able to fairly accurately reproduce the time of the lava flow advance during the 2006 Etna eruption leading to very plausible flow predictions. MAGFLOW is intended for use in emergency response situations during an eruption to quickly forecast the lava flow path over some time interval from the immediate future to a long-time forecast. Major discrepancies between the observed and simulated paths occurred in the early phase of the 2006 eruption due to an underestimation of the initial flow rate, and at the time of the overlapping with the 2004-2005 lava flow. Very good representations of the areas likely to be inundated by lava flows were obtained when we adopt a time-varying effusion rate and include the 2004-2005 lava flow field in the Digital Elevation Model (DEM) of topography.
    Description: Published
    Description: 1050-1060
    Description: 5V. Processi eruttivi e post-eruttivi
    Description: JCR Journal
    Description: open
    Keywords: Lava Flow ; Etna volcano ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.01. Computational geophysics::05.01.02. Cellular automata, fuzzy logic, genetic alghoritms, neural networks ; 05. General::05.01. Computational geophysics::05.01.05. Algorithms and implementation
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  • 55
    Publication Date: 2020-11-30
    Description: Auckland, New Zealand is unique in being a metropolitan area built on an active volcanic field. Despite the small size and intensity of Auckland eruptions, the risk from tephra fall is high because of the high density of buildings and lifelines. The nature of this threat can be evaluated by comparisons with historical Strombolian and Hawaiian eruptions, which have occurred in non-populated areas. Cone-building phases of such eruptions are typically protracted, i.e., weeks to months in duration, prolonging the period during which emergency managers will have to fine tune mitigation for numerous parameters such as fluctuations in intensity and wind shifts. Rapid cone growth during future eruptions will define a region of some 30 to 100 ha where complete destruction will occur on a time scale of hours. The cost of this destruction is likely to range between NZ$200M and NZ$1.4B (ca. US$130M to US$900M). Beyond this, we have modeled the cumulative long-term effect of the build-up of a downwind blanket of lapilli and ash by estimating accumulation rates for three phases of the 1959 Kīlauea Iki eruption in Hawaii. The effect of changing wind direction was evaluated using low-level wind data from Auckland. These results show that intervals between 4 and 100 h will lapse before onset of significant damage to buildings.
    Description: Published
    Description: 138-149
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: reserved
    Keywords: tephra hazard ; Auckland volcanic field ; cone growth ; tephra fall ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 56
    Publication Date: 2020-11-17
    Description: high-pressure behavior of three synthetic amphiboles crystallized with space group P21/m at room conditions in the system Li2O–Na2O–MgO–SiO2–H2O has been studied by in situ synchrotron infrared absorption spectroscopy. The amphiboles have compositions ANa B(NaxLi1 ¡ xMg1) CMg5 Si8 O22(OH)2 with x = 0.6, 0.2 and 0.0, respectively. The high-P experiments up to 32 GPa were carried out on the U2A beamline at Brookhaven National Laboratory (NY, USA) using a diamond anvil cell under non-hydrostatic or quasi-hydrostatic conditions. The two most intense absorption bands in the OH-stretching infrared spectra can be assigned to two non-equivalent O–H dipoles in the P21/m structure, bonded to the same local environment M1M3Mg3–OH–ANa, and pointing toward two diVerently kinked tetrahedral rings. In all samples these bands progressively merge to give a unique symmetrical absorption with increasing pressure, suggesting a change in symmetry from P21/m to C2/m. The pressure at which the transition occurs appears to be linearly correlated to the aggregate B-site dimension. The infrared spectra collected for amphibole B(Na0.2Li0.8Mg1) in the frequency range 50 to 1,400 cm¡1 also show a series of changes with increasing pressure. The data reported here support the inference of Iezzi et al. (Am Miner 91:479–482, 2006a) regarding a new high-pressure C2/m amphibole polymorph characterized by two equivalent and kinked double-chains, stable at very high-pressure.
    Description: Published
    Description: 343–354
    Description: 2IT. Laboratori analitici e sperimentali
    Description: JCR Journal
    Description: reserved
    Keywords: High-pressure ; B-site dimension ; 04. Solid Earth::04.01. Earth Interior::04.01.04. Mineral physics and properties of rocks
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  • 57
    Publication Date: 2020-11-16
    Description: Here we report the results of the analysis of a GPS velocity field in the Umbria–Marche Apennines (central Italy) obtained from the integration of diverse geodetic networks. The velocity field obtained shows a high degree of consistency both spatially and in terms of comparison with independent information, despite the limited time span of some GPS stations. Starting from the velocity field we derive a continuous strain rate field applying a spline interpolation technique which provide a smooth estimate of the deformation field. The main feature of the resulting strain rate field is a continuous high (N50 nanostrain/year) strain rate belt coincident with the area of largest historical and instrumental seismic release. The model directions of the principal axes agree with geological and seismological information indicating NE–SW extension. We transform the strain rate field into geodetic moment rate using the Kostrov formula to evaluate the potential seismic activity of the region and compare it with actual seismic release in the last 720 years from MwN5.5 earthquakes. This comparison highlights a large possible deficit in the seismic release with respect to the overall potential seismic activity, particularly concentrated in the northern part of the study area. This discrepancy can be resolved with either a large amount of seismicity to be released in the near future or significant aseismic slip and deformation.
    Description: Published
    Description: 3-12
    Description: 2T. Deformazione crostale attiva
    Description: JCR Journal
    Description: reserved
    Keywords: GPS ; crustal deformation ; Northen Apennines ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 58
    Publication Date: 2020-11-16
    Description: The presence of quarry and mine blasts in seismic catalogues is detected using the Wiemer and Baer (Bull Seism Soc Am 90(2):525–530, 2000) algorithm. The procedure is based on the observation that quarry blasts generally take place during daytime hours: the areas with a high ratio of daytime and night-time events are likely to be regions with quarry activity. In the first part of this work we have tested the method, using both a synthetic and a regional catalogue; in the second part the procedure has been applied to some of the European regional catalogues available on line. The comparison between the results obtained and the location of known quarries and mines for the analysed catalogues confirms the reliability of the methodology in identifying mining areas.
    Description: This research was partially supported by the transnational access activity of the European Union project NERIES (contract number 026130)
    Description: Published
    Description: 229–249
    Description: 4IT. Banche dati
    Description: JCR Journal
    Description: open
    Keywords: quarry blast; mine blast; seismic catalogue ; 05. General::05.01. Computational geophysics::05.01.04. Statistical analysis
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  • 59
    Publication Date: 2020-11-25
    Description: The Mesa del Caballo trench assessment confirms the Holocene activity of the main strand of the Boconó fault at the Apartaderos pull-apart basin. Fifteen earthquakes, of which fourteen have been radiocarbon dated, have been recognized, spanning the last 20,500 yr. Recurrence intervals of these ≥7 magnitude events are variable. The dominant mode of recurrence is 400–450 yr, and the second one is 900 yr. Eventually some events are 1400–1800 yr apart. We suspect that our seismic record may be incomplete. This could be easily justified by several conditions: most of the earthquake recognitions is based on open-crack filling and they superpose spatially (eventually masking or destroying older fills), trenching may miss some events because the fault is made of en echelon Riedel shears, and a short return period may lead to faint differences between paleosoils few hundreds years of age apart. This trench also images an older activity of the fault, as evidenced by plentiful earthquake-triggered liquefaction features, as well as slumping and rotational sliding. By comparing paleoseismic results between the Morro de Los Hoyos and Mesa del Caballo trenches, it appears that both fault strands bounding the Apartaderos pull-apart basin move simultaneously. Besides, the main strand also coseismically slips twice in between those common events. In other words, the seismic scenario could be that the northern strand recurs every 1200–1350 yr while the southern does every 400– 450 yr. This is also in agreement with a respective slip share of 25 and 75% of the 9–10 mm/yr average slip of the Boconó fault in the Mérida Andes central sector.
    Description: Published
    Description: 38-53
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: reserved
    Keywords: Active faults ; South America ; Paleoseismology ; 04. Solid Earth::04.04. Geology::04.04.01. Earthquake geology and paleoseismology
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  • 60
    Publication Date: 2020-11-16
    Description: Geological, geophysical and geotechnical investigations, for the characterization of the strong-motion recording sitesmanaged by the ItalianCivil Protection, have been carried out in the framework of the project “Italian strong-motion database in the period 1972–2004”. The project aimed at creating an updated database of strong-motion data acquired in Italy by different institutions in the time span 1972–2004, and at improving the quality of disseminated data. This article illustrates the state of the recording site characterization before the beginning of the project, explains the criteria adopted to select the sites where geophysical/ geotechnical investigation have been performed and describes the results of the promoted field surveys.
    Description: Published
    Description: 1189–1207
    Description: 4IT. Banche dati
    Description: JCR Journal
    Description: open
    Keywords: site ; characterization ; 04. Solid Earth::04.06. Seismology::04.06.04. Ground motion
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  • 61
    Publication Date: 2020-11-16
    Description: Using a Monte Carlo method based on a random walk in ad hoc N-dimensional phase space, we construct N random time series having prescribed coherence spatial decay. We apply the method in seismology by designing a numerical experiment to investigate how the coherence of the bedrock motion relates to the coherence of the surface ground motion in a sedimentary valley. The main features of the coherence behavior in the valley are found to tie in with data analysis and field observations.
    Description: Part of the research activities have been carried out by A. Caserta, for his PhD study, in cooperation with the Charles University in Prague (Czech Republic) and in the frame of the projects GACR 205/07/0502 and MSM 0021620860.
    Description: Published
    Description: 133-138
    Description: 5T. Sismologia, geofisica e geologia per l'ingegneria sismica
    Description: JCR Journal
    Description: reserved
    Keywords: Coherence of seismic waves ; Monte Carlo numerical simulations ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis
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  • 62
    Publication Date: 2020-11-18
    Description: By analyzing surface latent heat flux (SLHF) data from the NCEP/NCAR Reanalysis Project for the period three months before and after the Sept. 3, 2010 MS 7.1 New Zealand earthquake, an isolated SLHF positive anomaly on Aug. 1, 2010 was found with a high value of about 160 W/m2 to the northeast of the epicenter. Historical data, background pixels, and wavelet transforms of time series were comprehensively analyzed to study the spatiotemporal features of the SLHF anomaly. After removing the influences of wind speed and cloud cover, the key factor leading to local SLHF anomalies is the surface temperature increment. Combined with GPS displacement observations and tectonic settings, we determined that the physical mechanism of the SLHF anomaly could possibly be attributed to hot underground materials related to high-temperature and high-pressure upwelling from the deep crust and mantle along the nearby subduction zone, thereby explaining the local temperature increment to the northeast of the epicenter, as well as in the center of the North Island and the southwest of the South Island. Furthermore, it changed the specific humidity between the ground and surface air, causing the local SLHF increment.
    Description: Published
    Description: 3273-3280
    Description: 1.7. Osservazioni di alta e media atmosfera
    Description: 1.10. TTC - Telerilevamento
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: open
    Keywords: remote sensing ; earthquakes ; precursors ; 01. Atmosphere::01.01. Atmosphere::01.01.05. Radiation ; 04. Solid Earth::04.02. Exploration geophysics::04.02.05. Downhole, radioactivity, remote sensing, and other methods ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 63
    Publication Date: 2020-12-17
    Description: The Neapolitan Yellow Tuff (NYT) is the product of the largest known trachytic phreatoplinian eruption. It covered an area larger than 1000 km2 with an estimated volume of about 40 km3 of erupted magma. During the course of the eruption a caldera collapsed within the previously formed Campanian Ignimbrite caldera. The resulting nested structure strongly influenced the following volcanic activity in the Campi Flegrei caldera. As previous dating of the NYT does not converge toward a unique result, a new set of 40Ar/39Ar age determinations has been carried out to better constrain the age of the eruption. Two variants of the 40Ar/39Ar dating method were applied to determine the age of the NYT eruption: (1) single-crystal total fusion (SCTF), on an individual phenocryst of feldspar, and (2) laser incremental heating (LIH), on bulk aliquots of feldspar phenocrysts. The results of the SCTF analyses show that the overall sample weighted mean age, derived from the conventional age calculation, is 15.6 ;0.8 ka. A weighted mean of the isochron age is 15.3 ;1.2 ka (2c), and has been assumed as the best indicator of age to be derived from the SCTF analyses. The LIH analyses results show that plateau ages vary from 15.4; 0.5 to 14.5; 0.5 ka. The overall weighted mean age of the isochron results is 14.9;0.4 ka (2c). This result has been assumed as the reference age for the NYT eruption, and agrees with the SCTF age. The new age obtained for the NYT deposits is of great relevance for the understanding of the evolution and the present state of the Campi Flegrei caldera and collocates the NYT in a crucial stratigraphical position to date the climatic oscillations that occurred between the Late Glacial and the Holocene.
    Description: Published
    Description: 157-170
    Description: partially_open
    Keywords: Neapolitan Yellow Tuff ; Campi Flegrei caldera ; 40Ar/39Ar dating method ; Geochronology ; Late Glacial ; Holocene ; 04. Solid Earth::04.04. Geology::04.04.02. Geochronology ; 04. Solid Earth::04.04. Geology::04.04.10. Stratigraphy ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 64
    Publication Date: 2020-12-14
    Description: This paper presents a new methodology for studying the evolution of curved mountain belts by means of paleomagnetic analyses performed on analogue models. Eleven models were designed aimed at reproducing various tectonic settings in thin-skinned tectonics. Our models analyze in particular those features reported in the literature as possible causes for peculiar rotational patterns in the outermost as well as in the more internal fronts. In all the models the sedimentary cover was reproduced by frictional low-cohesion materials (sand and glass micro-beads), which detached either on frictional or on viscous layers. These latter were reproduced in the models by silicone. The sand forming the models has been previously mixed with magnetite-dominated powder. Before deformation, the models were magnetized by means of two permanent magnets generating within each model a quasi-linear magnetic field of intensity variable between 20 and 100 mT. After deformation, the models were cut into closely spaced vertical sections and sampled by means of 1x1-cm Plexiglas cylinders at several locations along curved fronts. Care was taken to collect paleomagnetic samples only within virtually undeformed thrust sheets, avoiding zones affected by pervasive shear. Afterwards, the natural remanent magnetization of these samples was measured, and alternating field demagnetization was used to isolate the principal components. The characteristic components of magnetization isolated were used to estimate the vertical-axis rotations occurring during model deformation. We find that indenters pushing into deforming belts from behind form non-rotational curved outer fronts. The more internal fronts show oroclinal-type rotations of a smaller magnitude than that expected for a perfect orocline. Lateral symmetrical obstacles in the foreland colliding with forward propagating belts produce non-rotational outer curved fronts as well, whereas in between and inside the obstacles a perfect orocline forms only when the ratio between obstacles’ distance and thickness of the cover is greater than 10. Finally, when a belt collides with an obstacle in the foreland oblique to the shortening direction the outer front displays rotations opposite in sign to oroclinal-type rotations, whereas the internal fronts seem to assume an "oroclinal type" rotational pattern. Furthermore rotation is easier in laterally unconfined models, i.e. when the wedge can "escape" laterally. The results from our models may be useful when compared to paleomagnetic rotations detected in natural arcs. In these cases, our results may allow for better understanding the tectonic setting controlling the genesis of curved mountain fronts, as is the case of the Gela Nappe of Sicily we compare with some of our models.
    Description: Published
    Description: 633-654
    Description: JCR Journal
    Description: reserved
    Keywords: paleomagnetism ; tectonic rotations ; physical models ; arcuate belts ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism
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  • 65
    Publication Date: 2020-12-15
    Description: no abstract
    Description: Unpublished
    Description: 1.1. TTC - Monitoraggio sismico del territorio nazionale
    Description: open
    Keywords: earthquake location ; source parameters ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 66
    Publication Date: 2020-12-09
    Description: This work presents the results of an assessment of the existence and concentration of 13 volatile organic compounds (VOCs) in groundwaters from 14 hydrological basins in Sicily (25,710 km2). On the basis of hydrological, hydrogeochemical and geological studies, 324 sampling points were selected. All groundwater sampled were collected twice, from October to December 2004 and from February to May 2005, and were analysed to determine the concentration and spatial distribution of the VOCs in the aquifers. The need to analyze a large number of samples in a short space of time so as to obtain quantitative analyses in trace concentration levels spurred us to create a new analytical method, both simple and sensitive, based on HS-SPME/GC/MS. The concentrations of VOCs measured in industrial and intensive agricultural unconfined aquifers were greater than those found in other aquifers. Tetrachloroethylene, chloroform, trichloroethylene and 1,2-dichloropropane were the most frequently detected VOCs. However, they exceeded the guideline values proposed by the EU in only three aquifers located near to industrial and intense agricultural areas.
    Description: Published
    Description: 3563-3577
    Description: 4.4. Scenari e mitigazione del rischio ambientale
    Description: JCR Journal
    Description: reserved
    Keywords: groundwater pollution ; VOCs ; aliphatic compounds ; groundwater monitoring ; 03. Hydrosphere::03.02. Hydrology::03.02.03. Groundwater processes
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  • 67
    Publication Date: 2020-12-02
    Description: In November 2008, the ionosonde station at Boulder, Colorado, USA (40.0°N; 105.3°W) became the host of a new ionosonde (VIPIR, Vertical Incidence Pulsed Ionospheric Radar) developed and built by Scion Associates. The VIPIR is a fully digital frequency agile radar that operates between 0.3 and 26 MHz. It features 8 digital receivers and a digital transmit exciter. Extremely high performance analog receive electronics and a 4 kW solid state amplifier provide interface to the real world. This work describes the application of Autoscala to the ionograms recorded by this ionosonde. First results, in terms of ionograms and autoscaled characteristics, are presented and discussed.
    Description: Published
    Description: 1156-1172
    Description: 1.7. Osservazioni di alta e media atmosfera
    Description: 3.9. Fisica della magnetosfera, ionosfera e meteorologia spaziale
    Description: JCR Journal
    Description: reserved
    Keywords: Autoscala ; Ionosphere ; Ionogram ; Electron Density ; Monitoring and Modelling ; 01. Atmosphere::01.02. Ionosphere::01.02.99. General or miscellaneous ; 01. Atmosphere::01.02. Ionosphere::01.02.05. Wave propagation ; 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques ; 05. General::05.07. Space and Planetary sciences::05.07.02. Space weather
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  • 68
    Publication Date: 2020-12-21
    Description: BREVIA
    Description: We report on the discovery in southern Egypt of an impact crater 45 m in diameter with a pristine rayed structure. Such pristine structures have been previously observed only on atmosphereless rocky or icy planetary bodies in the Solar System. This feature and the association with an iron meteorite impactor and shock metamorphism provides a unique picture of small-scale hypervelocity impacts on the Earth's crust. Contrary to current geophysical models, ground data indicate that iron meteorites with masses of the order of tens of tons can penetrate the atmosphere without significant fragmentation.
    Description: Published
    Description: 804
    Description: 1.8. Osservazioni di geofisica ambientale
    Description: 3.8. Geofisica per l'ambiente
    Description: JCR Journal
    Description: open
    Keywords: Impact crater ; Egypt ; geophysical exploration ; ataxite ; 04. Solid Earth::04.04. Geology::04.04.03. Geomorphology
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  • 69
    Publication Date: 2020-12-03
    Description: We use Global Positioning System (GPS) velocities and dislocation modeling to investigate the rate and nature of interseismic strain accumulation in the area affected by the 1908 Mw 7.1 Messina earthquake (southern Italy) within the framework of the complex central Mediterranean microplate kinematics. Our data confirm a change in the velocity trends between Sicily and Calabria, moving from NNW-ward to NE- ward with respect to Eurasia, and detail a fan-like pattern across the Messina Straits where maximum extensional strain rates are ~65 nanostrains/yr. Extension normal to the coast of northern Sicily is consistent with the presence of SW–NE trending normal faults. Half-space dislocation models of the GPS velocities are used to infer the slip-rates and geometric fault parameters of the fault zone that ruptured in the Messina − 1.3 earthquake. The inversion, and the bootstrap analysis of model uncertainties, finds optimal values of 3. 5 + 2.0 − 0.2− 0.7 and 1.6 + 0.3 mm/yr for the dip–slip and strike–slip components, respectively, along a 30 + 1.1° SE-ward dipping normal fault, locked above 7.6−2.9 km depth. By developing a regional elastic block model that + 4.6 accounts for both crustal block rotations and strain loading at block-bounding faults, and adopting two different competing models for the Ionian–Calabria convergence rates, we show that the measured velocity gradient across the Messina Straits may be significantly affected by the elastic strain contribution from other nearby faults. In particular, when considering the contribution of the possibly locked Calabrian subduction interface onto the observed velocity gradients in NE-Sicily and western Calabria, we find that this longer wavelength signal can be presently super-imposed on the observed velocity gradients in NE-Sicily and Calabria. The inferred slip-rate on the Messina Fault is significantly impacted by elastic strain from the subduction thrust. By varying the locking of the subduction thrust fault, in fact, the Messina Fault slip-rate varies from 0 to 9 mm/yr.
    Description: Published
    Description: 347-360
    Description: 1.9. Rete GPS nazionale
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: open
    Keywords: Messina Straits ; Global Positioning System ; strain accumulation ; plate kinematics ; dislocation modeling ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations ; 04. Solid Earth::04.03. Geodesy::04.03.06. Measurements and monitoring ; 04. Solid Earth::04.03. Geodesy::04.03.07. Satellite geodesy ; 04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk ; 04. Solid Earth::04.07. Tectonophysics::04.07.04. Plate boundaries, motion, and tectonics ; 04. Solid Earth::04.07. Tectonophysics::04.07.06. Subduction related processes ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
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  • 70
    Publication Date: 2020-12-15
    Description: Four sediment cores were analysed in order to determine the sedimentary processes associated with the channel-ridge depositional system that characterise the George V Land continental margin on the Wilkes Land. The sedimentary record indicates that the WEGA channel was a dynamic turbiditic system up to M.I.S. 11. After this time, the channel became a lower-energy environment with sediments delivered to the channel through high-density bottom waters that we identify to be the high salinity shelf waters (HSSW) forming on the shelf area. The HSSW entrains the fine-grained sediments of the shelf area and deliver them to the continental rise. The biostratigraphy and facies of the sediments within the WEGA channel indicate that the HSSW down flow was active also during last glacial. The change from a turbiditic system to a lowenergy bottom current system within the WEGA channel likely reflects a different ice-flow pattern, with ice-sheet reaching the continental shelf edge only within the ice trough (ice stream).
    Description: Published
    Description: 909 - 926
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: restricted
    Keywords: High salinity shelf water ; Turbidity currents ; Glacio-marine depositional processes ; Marine isotopic stage 11 ; Glacial dynamic changes ; 02. Cryosphere::02.02. Glaciers::02.02.05. Ice dynamics ; 04. Solid Earth::04.04. Geology::04.04.08. Sediments: dating, processes, transport ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism
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  • 71
    Publication Date: 2021-01-27
    Description: The eruptive dynamics of volcanic systems are largely controlled by the viscosity of deforming magma. Here we report the results of a series of high-temperature, high-pressure experiments at conditions relevant for volcanic conduits (250 MPa confining pressure and temperature between 500 °C and 900 °C) that were undertaken to investigate the rheology of magma with crystal fractions varying between 0.5 and 0.8 (50 to 80 wt.%) at different strain-rate conditions. The experiments demonstrate that the presence of crystals increases the relative viscosity (ratio between the viscosity of the mixture and the viscosity of the melt phase) of magmas and additionally induces a decrease of the relative viscosity with increasing strain-rate (shear thinning, non-Newtonian behavior). The experimental results, combined with existing data at low crystal fractions (0–0.3), were used to develop a semi-empirical parameterization that describes the variations of relative viscosity for crystal fractions between 0 and 0.8 and accounts for the complex non-Newtonian rheology of crystal-bearing magmas. The new parameterization, included into numerical models simulating the magma ascent dynamics, reveals that strain-rate-dependent rheology significantly modifies the dynamic behavior inside volcanic conduits, particularly affecting the magma fragmentation conditions.
    Description: Published
    Description: 402-419
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: partially_open
    Keywords: magma rheology ; experimental deformation ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
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  • 72
    Publication Date: 2021-01-25
    Description: Continuous marine successions covering the Middle Miocene Climate Transition (MMCT; ∼15–13.7 Ma) are scarce and the lack of a high-resolution magnetobiostratigraphic framework hampers the construction of astronomically tuned age models for this time interval. The La Vedova High Cliff section, exposed along the coast of the Cònero Riviera near Ancona (Italy), is one of the few Mediterranean sections covering the critical time interval of the MMCT. Starting from an initial magnetobiostratigraphic age model, a robust astronomical tuning was constructed for the interval between 14.2 and 13.5 Ma, using geochemical element data and time series analysis. A shift in δ18O of bulk sediment towards heavier values occurs between ∼13.92 and 13.78 Ma and could be related to the Mi3b oxygen isotope event, which reflects the rapid expansion of the East Antarctic Ice Sheet in the middle Miocene. The onset of the CM6 carbon excursion is reflected in the bulk record by a rapid increase in δ13C at 13.86 Ma. Our results confirm the proposition that these events coincide with a 405-kyr minimum in eccentricity and a node in obliquity related to the ∼1.2 Myr cycle. From 13.8 Ma onwards, distinct quadruplet cycles containing sapropelitic sediments were deposited. This may suggest a causal connection between the main middle Miocene cooling step and the onset of sapropel formation in the Mediterranean.
    Description: Published
    Description: 249–261
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: restricted
    Keywords: Middle Miocene ; Mediterranean ; astronomical tuning ; paleomagnetism ; biostratigraphy ; environmental changes ; orbital forcing ; sapropels ; 04. Solid Earth::04.04. Geology::04.04.10. Stratigraphy ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism
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  • 73
    Publication Date: 2021-03-01
    Description: On September 6, 2002, aML =5.6 earthquake, occurring some tens of kilometres offshore from the Northern Sicilian coast (Southern Tyrrhenian Sea), slightly damaged the city of Palermo and surroundings (degree 6 in the European Macroseismic Scale 1998). The macroseismic investigation of the shock and a detailed study of effects of the main earthquakes which affected Palermo in the past have been performed in order to evaluate the seismic response of the city. Moreover, the comparison of the recent event, which is instrumentally constrained, with historical earthquakes allows us to infer new insights on the seismogenic sources of the area, that seem located offshore in the Tyrrhenian sea. In the last 500 years, Palermo has never been completely destroyed but has suffered effects estimated between intensities 6 and 8 EMS-98 many times (1693, 1726, 1751, 1823, 1940, 1968, 2002). The damage scenarios of the analysed events have shown that damage distribution is strongly conditioned by soil response in the different parts of the city and by a high building vulnerability, mainly in the historical centre and in the south-eastern zone of the modern city. As a matter of fact, Palermo has always suffered greater effects than those reported for other nearby localities. The hazard assessment obtained using observed site intensities has shown that the probability of occurrence for intensity 8 (the strongest intensity observed in Palermo) exceeds 99% for 550 years, while the estimated mean return period is 152 ± 40 years. These results, in connection with building vulnerability due to the urban expansion before the introduction of seismic code, suggest that the city is exposed to a relatively high seismic risk.
    Description: Published
    Description: 525-543
    Description: partially_open
    Keywords: intensity ; damage ; earthquakes ; Italy ; macroseismics ; Palermo ; seismic hazard ; vulnerability ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 74
    Publication Date: 2021-04-07
    Description: no abstract
    Description: Published
    Description: 245
    Description: 3.6. Fisica del vulcanismo
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: open
    Keywords: volcanic eruption ; aircraft ; volcanic plumes ; ash clouds ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
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  • 75
    Publication Date: 2021-05-17
    Description: Papandayan is a stratovolcano situated in West Java, Indonesia. Since the last magmatic eruption in 1772,only few hydrothermal explosions have occurred. An explosive eruption occurred in November 2002 and ejected ash and altered rocks. The altered rocks show that an advanced argillic alteration took place in the hydrothermal system by interaction between acid fluids and rocks. Four zones of alteration have been defined and are limited in extension and shape along faults or across permeable structures at different levels beneath the active crater of the volcano. At the present time, the activity is centered in the northeast crater with discharge of low temperature fumaroles and acid hot springs. Two types of acid fluids are emitted in the crater of Papandayan volcano: (1) acid sulfate-chloride waters with pH between 1.6 and 4.6 and (2) acid sulfate waters with pH between 1.2 and 2.5. The water samples collected after the eruption on January 2003 reveal an increase in the SO4/Cl and Mg/Cl ratios. This evolution is likely explained by an increase in the neutralization of acid fluids and tends to show that water–rock interactions were more significant after the eruption. The evolution in the chemistry observed since 2003 is the consequence of the opening of new fractures at depth where unaltered (or less altered) volcanic rocks were in contact with the ascending acid waters. The high δ34S values (9–17‰) observed in acid sulfatechloride waters before the November 2002 eruption suggest that a significant fraction of dissolved sulfates was formed by the disproportionation of magmatic SO2. On the other hand, the low δ34S (−0.3–7‰) observed in hot spring waters sampled after the eruption suggest that the hydrothermal contribution (i.e. the surficial oxidation of hydrogen sulfide) has increased.
    Description: Published
    Description: 276-286
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: 2.4. TTC - Laboratori di geochimica dei fluidi
    Description: JCR Journal
    Description: reserved
    Keywords: Papandayan volcano ; Indonesia ; phreatic eruption ; hydrothermal system ; fluid geochemistry ; advanced argillic alteration ; gas geochemistry ; 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::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 76
    Publication Date: 2021-05-11
    Description: The CO2 laser-based lidar ATLAS has been used to study the Stromboli volcano plume. ATLAS measured water vapor concentration in cross-sections of the plume and wind speed at the crater. Water vapor concentration and wind speed were retrieved by differential absorption lidar and correlation technique, respectively. Lidar returns were obtained up to a range of 3 km. The spatial resolution was 15 mand the temporal resolution was 20 s. By combining these measurements, the water vapor flux in the Stromboli volcano plume was found. To our knowledge, it is the first time that lidar retrieves water vapor concentrations in a volcanic plume.
    Description: Published
    Description: 1295–1298
    Description: 1.10. TTC - Telerilevamento
    Description: JCR Journal
    Description: reserved
    Keywords: Lidar ; Volcanic plume ; DIAL ; Water vapor ; 04. Solid Earth::04.02. Exploration geophysics::04.02.01. Geochemical exploration ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 77
    Publication Date: 2021-04-07
    Description: This paper presents stable isotopic results (oxygen and carbon) from both modern and Late Pleistocene-Holocene shells of the land snail Eobania vermiculata (Müller, 1774) from Favignana Island (Sicily). It aims to contribute to the understanding of climate and vegetation history of this region during formation of Upper Palaeolithic, Mesolithic and Meso-Neolithic deposits of Grotta d’Oriente (ORT). Results from both an evaporative model (FBM) and an empirical regional isotopic model (i.e. linear relation between oxygen isotopic composition of shells (δ18Os) and those of local precipitation (δ18Op)) indicate that the δ18Os values of modern specimens are mainly controlled by local temperature, relative humidity and δ18Op at the time of snail activity. Data also suggest that the modern snails are nocturnally active almost all-year round in the study area. The carbon isotopic compositions of shells (δ13Cs) of the same specimens indicate a diet prevalently (or exclusively) composed of C3 vegetation. The δ18Os values of Late Pleistocene specimens suggest that climate conditions at ∼14.2 ka cal BP were similar to the present day, in agreement with additional δ18Os records from southern Italy. By contrast, early-middle Holocene shells are notably 18O-depleted and suggest wetter conditions, possibly combined with a decrease in isotopic composition of precipitation source, compared to the present day. When compared with regional palaeoclimatic records a large-scale isotopic response to millennial-scale changes in atmospheric and hydrological conditions (e.g. enhanced rainfall) in the central-eastern Mediterranean is observed during the early-middle Holocene. The δ13Cs of Late Pleistocene and Holocene specimens are consistently higher than those of modern ones. For the Late Pleistocene, this could be reasonably explained in terms of water-stressed vegetation. On the other hand, this seems to be less valid for Holocene counterparts when the climate was wetter. Probably δ13Cs values result from the combination of distinct competing factors, involving atmospheric CO2 concentration, seasonal water budget, vegetation type-cover and other carbon sources. Results reveal coherent relationships between regional δ18Os and δ13Cs, demonstrating that Late Pleistocene-Holocene land snail shell remains from archaeological sites may provide useful snapshots of past seasonal climate conditions.
    Description: Published
    Description: 76-87
    Description: 3.7. Dinamica del clima e dell'oceano
    Description: JCR Journal
    Description: reserved
    Keywords: Landsnail ; paleoclimate ; stable isotopes ; 03. Hydrosphere::03.01. General::03.01.06. Paleoceanography and paleoclimatology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 78
    Publication Date: 2021-06-16
    Description: Monthly averaged total volume transport of the Indonesian throughflow (ITF) estimated by 14 global ocean data assimilation (ODA) products that are decade to multi-decade long are compared among themselves and with observations from the INSTANT Program (2004-2006). The ensemble averaged, time-mean value of ODA estimates is 13.6 Sv (1 Sv = 106 m3/s) for the common 1993-2001 period and 13.9 Sv for the 2004-2006 INSTANT Program period. These values are close to the 15-Sv estimate derived from INSTANT observations. All but one ODA time-mean estimate fall within the range of uncertainty of the INSTANT estimate. In terms of temporal variability, the average scatter among different ODA estimates is 1.7 Sv, which is substantially smaller than the magnitude of the temporal variability simulated by the ODA systems. Therefore, the overall “signal-to-noise” ratio for the ensemble estimates is larger than one. The best consistency among the products occurs on seasonal-to-interannual time scales, with generally stronger (weaker) ITF during boreal summer (winter) and during La Nina (El Nino) events. The averaged scatter among different products for seasonal-to-interannual time scales is approximately 1 Sv. Despite the good consistency, systematic difference is found between most ODA products and the INSTANT observations. All but the highest-resolution (18-km) ODA product show a dominant annual cycle while the INSTANT estimate and the 18-km product exhibit a strong semi-annual signal. The coarse resolution is an important factor that limits the level of agreement between ODA and INSTANT estimates. Decadal signals with periods of 10-15 years are seen. The most conspicuous and consistent decadal change is a relatively sharp increase in ITF transport during 1993-2000 associated with the strengthening tropical Pacific trade wind. Most products do not show a weakening ITF after the mid-1970s’ associated with the weakened Pacific trade wind. The scatter of ODA estimates is smaller after than before 1980, reflecting the impact of the enhanced observations after the 1980s. To assess the representativeness of using the average over a three-year period (e.g., the span of the INSTANT Program) to describe longer-term mean, we investigate the temporal variations of the three-year low-pass ODA estimates. The median range of variation is about 3.2 Sv, which is largely due to the increase of ITF transport from 1993 to 2000. However, the three-year average during the 2004-2006 INSTANT Program period is within 0.5 Sv of the long-term mean for the past few decades.
    Description: Published
    Description: 3.7. Dinamica del clima e dell'oceano
    Description: JCR Journal
    Description: partially_open
    Keywords: ocean modelling ; data assimilation ; Indonesian region ; 03. Hydrosphere::03.01. General::03.01.04. Ocean data assimilation and reanalysis
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 79
    Publication Date: 2021-06-21
    Description: Earthquake early warning systems (EEWS), based on real-time prediction of ground motion or structural response measures, may play a role in re- ducing vulnerability and/or exposure of buildings and lifelines. Indeed, seismologists have recently developed efficient methods for real-time es- timation of an event’s magnitude and location based on limited informa- tion of the P-waves. Therefore, when an event occurs, estimates of magni- tude and source-to-site distance are available, and the prediction of the structural demand at the site may be performed by Probabilistic Seismic Hazard Analysis (PSHA) and then by Probabilistic Seismic Demand Analysis (PSDA) depending upon EEWS measures. Such an approach contains a higher level of information with respect to traditional seismic risk analysis and may be used for real-time risk management. However, this kind of prediction is performed in very uncertain conditions which may affect the effectiveness of the system and therefore have to be taken into due account. In the present study the performance of the EWWS under development in the Campania region (southern Italy) is assessed by simu- lation. The earthquake localization is formulated in a Voronoi cells ap- proach, while a Bayesian method is used for magnitude estimation. Simu- lation has an empirical basis but requires no recorded signals. Our results, in terms of hazard analysis and false/missed alarm probabilities, lead us to conclude that the PSHA depending upon the EEWS significantly improves seismic risk prediction at the site and is close to what could be produced if magnitude and distance were deterministically known.
    Description: Published
    Description: 211-232
    Description: 4.1. Metodologie sismologiche per l'ingegneria sismica
    Description: reserved
    Keywords: Earthquake Early ; Campania Region ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics ; 04. Solid Earth::04.06. Seismology::04.06.04. Ground motion ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 80
    Publication Date: 2021-06-25
    Description: Unstructured hexahedral mesh generation is a critical part of the model- ing process in the Spectral-Element Method (SEM). We present some ex- amples of seismic wave propagation in complex geological models, automati- cally meshed on a parallel machine based upon CUBIT (Sandia Laboratory, cubit.sandia.gov), an advanced 3D unstructured hexahedral mesh genera- tor that offers new opportunities for seismologist to design, assess, and improve the quality of a mesh in terms of both geometrical and numerical accuracy. The main goal is to provide useful tools for understanding seismic phenomena due to surface topography and subsurface structures such as low wave-speed sedimentary basins. Our examples cover several typical geophysical problems: 1) “layer-cake” volumes with high-resolution topography and complex solid- solid interfaces (such as the Campi Flegrei Caldera Area in Italy), and 2) models with an embedded sedimentary basin (such as the Taipei basin in Taiwan or the Grenoble Valley in France).
    Description: Published
    Description: 3.1. Fisica dei terremoti
    Description: 4.1. Metodologie sismologiche per l'ingegneria sismica
    Description: reserved
    Keywords: meshing ; seismic wave propagation ; spectral element methond ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis ; 05. General::05.01. Computational geophysics::05.01.05. Algorithms and implementation
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 81
    Publication Date: 2021-06-16
    Description: In this paper we present the results of preliminary geomorphic and trenching investigations along the Kahrizak fault. This fault is located south of the highly populated metropolis of Tehran and represents one of the main structures in the area containing important seismic potential. The Kahrizak fault has a very clear expression at the surface where it forms a prominent 35-km-long, 15-m-high scarp on Holocene alluvial deposits. The fault strikes N70°-80°W and dips to the north. Movement is prevalently right-lateral with the northern side of the fault up. Trench excavations exposed a sequence of weathered, massive, alluvial deposits which are dated, by means of radiometric methods, to the Holocene. In the trenches the sequence is intensely deformed by north-dipping, high- and low-angle faults within a 30-m-wide zone. On the basis of stratigraphic and structural relations, some evidence for individual Holocene earthquakes is found; however, we were not able to reconstruct the seismic history of the fault nor to evaluate the size of deformation produced by each event. Because of the possible ~10 m offset of ancient linear hydraulic artifacts (qanáts), that cross the fault, we hypothesize that the most recent event may have occurred in historical times (more recent than 5000 yr B.P.) and it may be one of those reported in this area by the current catalogues of seismicity. Based on these preliminary investigations we estimate an elapsed time between 5000 and 800 years, a maximum slip per event dmax of ~10 m, a minimum Holocene vertical slip rate of ~1 mm/yr versus a horizontal slip rate of ~3.5 mm/yr, a maximum of ~3000 years for the average recurrence time, and an expected Mw = 7.0 to 7.4. These can be considered as a first-hand reference for the activity on this fault.
    Description: Published
    Description: 187-199
    Description: 3.2. Tettonica attiva
    Description: N/A or not JCR
    Description: reserved
    Keywords: Iran ; paleoseismicity ; geomorphology ; seismic hazard assessment ; 04. Solid Earth::04.04. Geology::04.04.01. Earthquake geology and paleoseismology ; 04. Solid Earth::04.04. Geology::04.04.03. Geomorphology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 82
    Publication Date: 2021-06-25
    Description: We report in this paper a systematic investigation of the chemical and isotopic composition of groundwaters flowing in the volcanic aquifer of Mt. Vesuvius during its current phase of dormancy, including the first data on dissolved helium isotope composition and tritium content. The relevant results on dissolved He and C presented in this paper reveal that an extensive interaction between rising magmatic volatiles and groundwaters currently takes place at Vesuvius. Vesuvius groundwaters are dilute (mean TDS 2800 mg/L) hypothermal fluids (mean T 17.7°C) with a prevalent alkaline-bicarbonate composition. Calcium-bicarbonate groundwaters normally occur on the surrounding Campanian Plain, likely recharged from the Apennines. D and 18O data evidence an essentially meteoric origin of Vesuvius groundwaters, the contribution from either Tyrrhenian seawater or 18O-enriched thermal water appearing to be small or negligible. However, the dissolution of CO2-rich gases at depth promotes acid alteration and isochemical leaching of the permeable volcanic rocks, which explains the generally low pH and high total carbon content of waters. Attainment of chemical equilibrium between the rock and the weathering solutions is prevented by commonly low temperature (10 to 28°C) and acid-reducing conditions. The chemical and isotope (C and He) composition of dissolved gases highlights the magmatic origin of the gas phase feeding the aquifer. We show that although the pristine magmatic composition may vary upon gas ascent because of either dilution by a soil-atmospheric component or fractionation processes during interaction with the aquifer, both 13C/12C and 3He/4He measurements indicate the contribution of a magmatic component with a 13C 0‰ and R/Ra of 2.7, which is consistent with data from Vesuvius fumaroles and phenocryst melt inclusions in olivine phenocrysts. A main control of tectonics on gas ascent is revealed by data presented in this paper. For example, two areas of high CO2 release and enhanced rock leaching are recognized on the western (Torre del Greco) and southwestern (Torre Annunziata–Pompeii) flanks of Vesuvius, where important NE-SW and NW-SE tectonic structures are recognized. In contrast, waters flowing through the northern sector of the volcano are generally colder, less saline, and CO2 depleted, despite in some cases containing significant concentrations of magmaderived helium. The remarkable differences among the various sectors of the volcano are reconciled in a geochemical interpretative model, which is consistent with recent structural and geophysical evidences on the structure of Somma-Vesuvius volcanic complex.
    Description: -European Union, -Ministero dell’Universita’ e della Ricerca Scientifica e Tecnologica; -CNR–Gruppo Nazionale per la Vulcanologia.
    Description: Published
    Description: 963–981
    Description: partially_open
    Keywords: isotopes ; water chemistry ; dissolved gases ; 03. Hydrosphere::03.02. Hydrology::03.02.03. Groundwater processes ; 03. Hydrosphere::03.04. Chemical and biological::03.04.03. Chemistry of waters ; 03. Hydrosphere::03.04. Chemical and biological::03.04.05. Gases ; 03. Hydrosphere::03.04. Chemical and biological::03.04.06. Hydrothermal systems ; 03. Hydrosphere::03.04. Chemical and biological::03.04.07. Radioactivity and isotopes ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 83
    Publication Date: 2020-10-29
    Description: In-situ falling-sphere viscometry using shadow radiography in a multianvil apparatus was conducted on a series of samples along the NaAlSi3O8–H2O join up to 2.8 wt.% H2O at the Spring-8 synchrotron radiation facility (Hyogo, Japan). This allowed us to determine viscosities normally too low to be measured at ambient pressure for hydrous silicate melts at high temperatures due to rapid devolatilization. Pressure was fixed at 2.5 GPa for all experiments allowing us to gauge the effect of chemical composition on viscosity. In particular, the series of samples allowed us to vary the melt's degree of polymerization while maintaining a constant Al to Si ratio. Our results show that, for all samples, viscosity decreases as a function of pressure between 1 atm and 2.5 GPa at 1550 °C, indicating that the pressure anomaly can still be observed as depolymerization of the melt increases from nominally 0 (dry albite liquid) to NBO/T=0.8 (assuming water speciation entirely as hydroxyl groups at experimental conditions). We also find that the magnitude of the decrease in viscosity over this pressure interval does not appear to be dependent on the amount of water in the melt (i.e., NBO/T). An explanation for this behavior might be that the molar volume, at least over this limited compositional range, is nearly constant and the effects of compression of these melts, though different in degree of polymerization, are similar.
    Description: Published
    Description: 2-9
    Description: JCR Journal
    Description: reserved
    Keywords: Viscosity ; Silicate melts ; High pressure ; 04. Solid Earth::04.01. Earth Interior::04.01.05. Rheology ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 84
    Publication Date: 2020-10-29
    Description: We report high-resolution magnetic measurements from two Mediterranean piston cores: LC07 (Sicily Strait) and LC10 (Ionian Sea). Magnetostratigraphic results and δ18O data provide age constraints for core LC07, where we investigate magnetic property variations for two age intervals (0-600 kyr and 660-1020 kyr). For core LC10, rock magnetic parameters appear to be climatically controlled and are used to derive an astronomically tuned age model for the interval between 780 and 1200 kyr. In core LC07, the dominant control on the magnetic properties appears to be glacial-interglacial variations in the concentration of biogenic magnetite. In addition, an increased contribution from high coercivity minerals (e.g. hematite and/or goethite) probably reflects an enhanced eolian input during glacial periods. Climatic control of magnetotactic bacterial populations has been previously suggested in other environments, but this is the first such report from the Mediterranean. In contrast, the rock magnetic response to Quaternary climatic variability in core LC10 seems to be better expressed by variations in the concentration of high coercivity magnetic minerals. The contrast between a dominantly detrital/eolian flux and a dominantly biogenic flux at the same time for the two Mediterranean settings might relate to the presence of an active current regime in the Sicily Strait, which might decrease delivery of an eolian component to the seafloor compared to the deep Ionian Sea.
    Description: Published
    Description: 195-209
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: 3.8. Geofisica per l'ambiente
    Description: JCR Journal
    Description: reserved
    Keywords: environmental magnetism ; biogenic magnetite ; eolian dust ; glacial-interglacial cycles ; Mediterranean Sea ; 04. Solid Earth::04.05. Geomagnetism::04.05.07. Rock magnetism
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 85
    Publication Date: 2020-10-26
    Description: One of the main objectives of the ITACA (ITalian ACcelerometric Archive) strong motion database, promoted by the Italian Department of Civil Protection, was to improve the characterization of the recording sites from a geological and geophysical point of view and to provide their seismic classification according to the seismic norms pertinent to Italy, namely the Eurocode 8 and the National Technical Norms for Constructions. A standard format to summarize the available information for the recording stations was first produced, in terms of a technical report dynamically linked to the database, i.e., some of the relevant information is automatically updated when the corresponding fields of the database are modified. Then, an important activity of collection, qualification and synthesis of available data was carried out, especially for stations that recorded the strongest earthquakes in Italy in the last 40 years, and for which a relevant number of studies have been published. In spite of this activity, among the more than 700 strong motion stations present in the ITACA database, only a limited number of them could be characterized by quantitative information on subsurface soil properties. For this reason, a dual seismic site classification criterion was implemented, either based on the standard Vs,30 scheme, or, in the absence of such information, based on an expert opinion supported by shallow geology maps, mostly at 1:100,000 scale, and when available on the H/V ratios calculated on recordings. Owing to the relevance in the Italian geographic and morphological context, a special care was also given to the topographic classification of stations, based on suitable criteria developed within a GIS environment.
    Description: Published
    Description: 1779-1796
    Description: 4.1. Metodologie sismologiche per l'ingegneria sismica
    Description: JCR Journal
    Description: open
    Keywords: ITACA database ; Strong motion station ; General characterization ; Site classification ; 04. Solid Earth::04.06. Seismology::04.06.04. Ground motion ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring ; 05. General::05.02. Data dissemination::05.02.02. Seismological data ; 05. General::05.09. Miscellaneous::05.09.99. General or miscellaneous
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  • 86
    Publication Date: 2020-11-17
    Description: Recent seismic swarms and hydrothermal activity suggest that the Quaternary volcanic complex of the Alban Hills may pose a threat to the city of Rome. A 350m scientific borehole was therefore drilled into this volcanic area to elucidate its inner structure for the first time. Wire-line logs were run in the borehole in order to characterize the physical properties of the rocks and their variations with depth. In particular, a detailed sonic log was run to measure the P-wave velocity from the well-head down to 110 m. To further investigate velocity changes, we carried out laboratory measurements of P and S elastic wave velocities and fluid permeability at effective pressures up to 70 MPa during both increasing and decreasing pressure cycles on selected core samples representative of the main volcanic units. Specifically, we studied samples from two pyroclastic units representative of two classes of volcanic deposits that are representative of the whole succession: (i) a coarse-grained, well-lithified facies (Pozzolane Rosse unit), containing abundant mm-to-cm lava clasts and crystals; and (ii) a fine-grained, matrix-supported pyroclastic deposit (Tufo Pisolitico di Trigoria unit), with rare lithic lava clasts and sparse pumice. Elastic wave velocities reveal significant differences between units and indicate how, within the same lithology, the different degree of lithification and presence of clasts can affect significantly physical property values. The mean laboratory value of the Pwave velocity for Pozzolane Rosse and Tufo Pisolitico di Trigoria units is respectively of 3.75 and 3.2 km/s at an effective pressure equivalent to that at the depth at which the sonic velocity was measured. Under increasing effective pressure a profound influence on the transport properties is observed. Permeability ranges from the order of 10−18 m2 for the Pozzolane Rosse unit to the order of 10−15 m2 for the Tufo Pisolitico di Trigoria unit, in good agreement with the shallow aquifer circulating in the shallower units.
    Description: Published
    Description: 161-169
    Description: 3V. Proprietà chimico-fisiche dei magmi e dei prodotti vulcanici
    Description: JCR Journal
    Description: reserved
    Keywords: Scientific borehole ; Volcanic rocks ; Physical properties ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks
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  • 87
    Publication Date: 2020-11-16
    Description: Volcanic edifices, such as Mt. Etna (Italy), are commonly subject to repeated cycles of stress over time due to the combination of magma emplacement from deep reservoirs to shallow depths and superimposed tectonic stresses. Such repeated stress cycles lead to anisotropic deformation and an increase in the level of crack damage within the rocks of the edifice and hence changes to their elastic moduli, which are a key parameter for reliable modelling of deformation sources. We therefore report results of changes in elastic moduli measured during increasing amplitude cyclic stressing experiments on dry and water-saturated samples of Etna basalt. In all experiments, the Young’s modulus decreased by approximately 30% over the total sequence of loading cycles, and the Poisson’s ratio increased by a factor of approximately 3 ± 0.5. Microseismicity, in terms of acoustic emission (AE) output, was also recorded throughout each experiment. Our results demonstrate that AE output only re-commences during any loading cycle when the level of stress where AE ceased during the unloading portion of the previous cycle is exceeded; a manifestation of the Kaiser stress-memory effect. In cycles where no AE output is generated, we also observe no change in elastic moduli. This result is observed for both mechanical and thermal stressing. Our results are interpreted in relation to measurements of volcano-tectonic seismicity and deformation at Mt. Etna volcano.
    Description: Published
    Description: 153-160
    Description: 3V. Proprietà chimico-fisiche dei magmi e dei prodotti vulcanici
    Description: JCR Journal
    Description: reserved
    Keywords: rock mechanics, elastic moduli, Etna basalt ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks
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  • 88
    Publication Date: 2020-11-30
    Description: This special issue of Journal of Seismology, dedicated to Archaeoseismology, shows the current trends of research in this young branch of seismology. The beginning of modern archaeoseismological practice during the 1980’s and the investigations made during the 1990’s were in many cases conditioned by the lack of cooperation among the spcialists from different scientific diciplines. Numerous publications resulted from the work of archaeologists, in some cases in collaboration with experts in earthquake-geology or seismology, but rarely such work included a complete and multidisciplinary approach and in situ analysis of the evidence. In many cases, archaeoseismological studies were limited to the detection of traces of past earthquakes in archaeological remains without a seismological perspective aiming to derive quantitative parameters necessary to fully describe a past earthquake (magnitude, etc.). In other cases, such investigations were limited to the analysis of archaeological reports of excavations made years or decades earlier. A step towards the quantification of seismological aspects was represented by the “territorial” approach, trying to reconstruct a picture of an earthquake by detecting its signs over a wider region. This procedure was, however, limited by the scarcity and reliability of published or unpublished archaeological material, usually adopted without a critical review.
    Description: Published
    Description: 393–394
    Description: 2TM. Divulgazione Scientifica
    Description: JCR Journal
    Description: open
    Keywords: Archaeoseismology, ; 04. Solid Earth::04.06. Seismology::04.06.05. Historical seismology
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    Type: article
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  • 89
    Publication Date: 2020-11-23
    Description: Scattering ratios R processed from the same raw data at 353 and 532 nm by different lidar groups agree within about 10 % for high and within about 4 % for low aerosol loading. In the main layer aerosol backscatter coefficients agree within about 30 % for high and within about 40 % for low aerosol loading
    Description: Published
    Description: Berlin, Germany
    Description: 1.8. Osservazioni di geofisica ambientale
    Description: open
    Keywords: NDCS ; LIDAR ; 01. Atmosphere::01.01. Atmosphere::01.01.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Conference paper
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  • 90
    Publication Date: 2020-11-17
    Description: TWODEE-2 is a FORTRAN 90 code based on previous code (TWODEE). It is designed to solve the shallow water equations for fluid depth, depth-averaged horizontal velocities and depth-averaged fluid density. The shallow layer approach used by TWODEE-2 is a compromise between the complexity of CFD models and the simpler integral models. It can be used for forecasting gas dispersion near the ground and/or for hazard assessment over complex terrains. The inputs to the model are topography, terrain roughness, wind measurements from meteorological stations and gas flow rate from the ground sources. Optionally the model can be coupled with the output of a meteorological processor which generates a zero-divergence wind field incorporating terrain effects. Model outputs are gas concentration, depth-averaged velocity, averaged cloud thickness and dose. The model can be a useful tool for gas hazard assessment by evaluating where and when lethal concentrations for humans and animals can be reached.
    Description: Published
    Description: 667-674
    Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio
    Description: JCR Journal
    Description: reserved
    Keywords: Dense gas transport ; Fortran code ; Gas hazard ; Computational model ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 05. General::05.01. Computational geophysics::05.01.99. General or miscellaneous ; 05. General::05.08. Risk::05.08.01. Environmental risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 91
    Publication Date: 2020-11-16
    Description: The present-day tectonic setting of the Italian peninsula is very complex and involves competing geodynamic processes. In this context, southern peninsular Italy is characterised by extension along the Apenninic belt and in the Tyrrhenian margin and by transpression in the Apulia-Gargano region. The extension is well defined by means of geological, seismological, and contemporary stress data. For the latter only few data are available in the Apulia-Gargano region, leaving the state of stress in that area unresolved. Here we develop a finite-element model of the southern Italian region in order to predict the contemporary stress field. Our model predictions are constrained by model-independent observations of the orientation of maximum horizontal stress (SHmax), the tectonic regime, and the horizontal velocities derived from GPS observations. We performed a blind test with 31 newly acquired SHmax orientations in the Southern Apennines. These new data come from the analysis of borehole breakouts performed in 46 deep oil exploration wells ranging in depth from 1300 to 5500 m. The model results agree with the stress data that define a prevailing NW-SE SHmax orientation along the Apenninic belt and foredeep and thus are capable to predict the stress field where no stress information is available. We first analyse how much model predictions, based on older data, deviate from present-day stress data and then recalibrate the models based on our new stress data, giving insight into the resolution of both models and data. In the studied region, which is affected by low deformation rates, we find that geodetic data alone cannot resolve such low levels of deformation due to the high relative measurement errors. We conclude that both GPS and stress data are required to constrain model results.
    Description: This research was supported by the Italian Presidenza del Consiglio dei Ministri - Dipartimento della Protezione Civile (DPC) through the INGV-DPC project S1.
    Description: Published
    Description: 193-204
    Description: 2T. Deformazione crostale attiva
    Description: JCR Journal
    Description: open
    Keywords: Neotectonics ; Borehole-breakouts ; Southern Apennines ; Finite-element models ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations ; 04. Solid Earth::04.03. Geodesy::04.03.08. Theory and Models ; 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 92
    Publication Date: 2020-11-16
    Description: Earthquake catalogues for Romania supply for 11th–15th century earthquakes located in the region of Vrancea records that consist of a complete set of parameters, including magnitude and depth. Scope of this paper is to verify the reliability and consistency of these parameters with the informative background as explicitly referenced by the catalogues. After retrieving the original sources they mention, the set of data appeared to be related almost exclusively to the Russian plain and too poor to be at the very origin of the parameter assessment. Data for 19th–20th century earthquakes, such as instrumental locations and CMT solutions, added to the understanding of the macroseismic response of the Russian plain to Vrancea earthquakes. On the one hand, the investigation and analysis of historical earthquake records for the fourteen events listed by the catalogues in the 11th–15th centuries has shown that for three earthquakes (1022, 1038, 1258) no primary sources could be traced, and three more earthquakes (1091, 1170 and 1328) are attested only by scarcely reliable records and had to be classified as doubtful, and one (1473) is simply a duplication of the 1471 event. On the other hand, the availability of data on recent earthquakes that may be compared to historical ones in terms of macroseismic effects allowed the authors to agree with the previous catalogue compilers’ solution with regard to both magnitude and depth of the past earthquakes for which do exist reliable primary historical records.
    Description: Published
    Description: 575–604
    Description: 4IT. Banche dati
    Description: JCR Journal
    Description: open
    Keywords: Vrancea earthquakes ; 11th-15th earthquakes ; 04. Solid Earth::04.06. Seismology::04.06.05. Historical seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 93
    Publication Date: 2020-11-12
    Description: The number of tornillo events has recently increased at the Vulcano Island, Italy. While only 15 tornillos were recorded during 2004–2006, 584 events occurred in 2007–2008. They were located just below La Fossa Crater at depths ranging between 0.1 and 1 km b.s.l. During two intervals in 2007–2008 increases in the number of tornillos took place at the same time as temperature and geochemical anomalies were observed. The spectral content of the tornillos, generally characterized by one–two dominant spectral peaks near 6 and 10 Hz, varied over time, with changes also noted in the quality factors. The simplest source mechanism proposed for tornillos is the free eigenvibration of a fluid volume within a crack or a conduit. Based on this model, we propose a causal relationship between the temperature and geochemical anomalies and the increases in numbers of tornillos. As the amount of hydrothermal fluids increases during the anomalies, the upward flux of fluids grows. The consequent changes in the pressure, temperature and dynamics of the system of cracks and conduits result in the generation of tornillos. Based on the fluid-filled crack/conduit model, the shallow depths of the sources and the values of the quality factors, the fluid within the resonant crack/conduit was inferred to be an ash–gas or water droplet–gas mixture. Moreover, the observed variations in the wavefield can be caused by small changes in the location of the source, in the source mechanism, or in the medium in between the source and the seismic station. Finally, another peculiar feature of tornillos is the amplitude modulation that can be explained as a result of a beating phenomenon.
    Description: Published
    Description: 377-393
    Description: 3V. Proprietà chimico-fisiche dei magmi e dei prodotti vulcanici
    Description: JCR Journal
    Description: reserved
    Keywords: Tornillos ; Vulcano Island ; Hydrothermal system ; Volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 94
    Publication Date: 2020-11-30
    Description: We present structural analysis, fluid inclusion data on calcite and quartz, and isotopic composition of calcite forming veins occurring in the upper crustal level and hosted in Oligocene sandstone in southern Tuscany (Italy). The veins have been analysed in two sites few kilometres apart, along well-exposed coastal cliffs and in an abandoned quarry. These two sites were at a different depths at the time of the vein formation with a Δh ~ 100 m. Structural analysis of veins provided estimations of stress ratio (Φ = (σ2 − σ3)/(σ1 − σ3)), driving stress ratio (R′ = (Pf − σ3)/(σ1 − σ3)) and fluid overpressure (ΔPo = Pf − σ3) at the time of vein formation. The estimated ΔPo is in the range of 42–103 MPa, Φ = 0.24 and R′ = 0.45, indicating that fluid pressure was higher than the intermediate principal stress at the time of veins formation. The veins' thickness (t) shows a clear power-law distribution (D = 1.8835 and R2 = 0.9762) in the lowermost site (coast) and a negative exponential distribution (a = 0.6943 and R2 = 0.9921) in the uppermost site (abandoned quarry). The vein thickness distributions have been used to compute the average transmissivity of the veins in the two sites. The computed transmissivity for the vein formation is ~ 10−4 m2 s−1, with higher values attained by the veins having negative exponential thickness distribution. Fluid inclusions studies highlighted that in both calcite and quartz, water-rich inclusions, with salinities of 2.2–4.3 wt.% NaCl equiv., and methane-rich inclusions were coevally trapped during fluid un-mixing processes. Thermogenic origin, from thermal maturation of organic matter present in the Macigno Formation, is proposed for methane. Whereas, the similarity between the δ18O (from 14.9 to 17.4‰) and δ13C (from −0.4 to −2.4‰) data of representative calcite veins and the isotopic composition (δ18O: 16.1‰, δ13C: −1.0‰) of host-rock carbonate component, indicates that the fluid which formed calcite was in isotopic equilibrium with the carbonates present in the Oligocene sandstones. The calculated pressure–temperature conditions during the formation of these inclusions are prevalently within the 40–145 MPa and 160–260 °C ranges. The highest pressure values approximate the lithostatic pressure (~ 120 MPa) computed from geological data and are coherent with a geothermal gradient ranges of 35–45 °C/km. Whereas, the lower pressure values are comparable with hydrostatic pressure conditions. The pressure range indicated by fluid inclusion data is also comparable with the fluid pressure estimated from structural analysis. The considerable pressure range can be related to pressure cycling between lithostatic and hydrostatic conditions as a consequence of fault-valve actions and rock fracturing with subsequent pressure recover due to self-sealing process.
    Description: Published
    Description: 118-138
    Description: 3.2. Tettonica attiva
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: reserved
    Keywords: Vein systems ; Fluid type ; Fluid pressure ; Fluid inclusions ; Upper crust ; Tuscany ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 95
    Publication Date: 2020-12-01
    Description: In this paper, we will shortly highlight some of the aspects that COST Action 296 on Mitigation of Ionospheric Effects on Radio Systems (MIERS) and International Reference Ionosphere (IRI) have in common in an attempt to define science rationale for collaboration between these two international projects.
    Description: Published
    Description: 1621-1623
    Description: 2A. Fisica dell'alta atmosfera
    Description: JCR Journal
    Description: open
    Keywords: COST296 Action MIERS ; IRI ; ionospheric monitoring and modelling ; 01. Atmosphere::01.02. Ionosphere::01.02.99. General or miscellaneous ; 05. General::05.07. Space and Planetary sciences::05.07.02. Space weather
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 96
    Publication Date: 2020-12-07
    Description: Low-field anisotropy of magnetic susceptibility (AMS) analyses were performed on 532 samples col-lected in 36 (mostly lower Pliocene to lower Pleistocene) marine clay sites from the Crotone basin, afore-arc basin located on top of the external Calabrian accretionary wedge. The Crotone basin formedsince mid-late Miocene under a predominant extensional tectonic regime, but it was influenced there-after by complex interactions with NW–SE left-lateral strike-faults bounding the basin, which also yieldedpost-1.2 Ma ~30◦counterclockwise block rotations. The basin is filled by continental to marine sedimentsyielding one of the thickest and best-exposed Neogene succession available worldwide. The deep-marinefacies – represented by blue-grey marly clays gave the best results, as they both preserved a clear mag-netic fabric, and provided accurate chronology based on previously published magnetostratigraphy andcalcareous plankton (i.e. foraminifers and nannofossils) biostratigraphy. Magnetic susceptibility rangeand rock magnetic analyses both indicate that AMS reflects paramagnetic clay matrix crystal arrange-ment. The fabric is predominantly oblate to triaxial, the anisotropy degree low (〈1.06), and the magneticfoliation mostly subparallel to bedding. Magnetic lineation is defined in 30 out of 36 sites (where thee12 angle is 〈35◦). By also considering local structural analysis data, we find that magnetic fabric wasgenerally acquired during the first tectonic phases occurring after sediment deposition, thus validatingits use as temporally dependent strain proxy. Although most of the magnetic lineations trend NW–SE andare orthogonal to normal faults (as observed elsewhere in Calabria), few NE–SW compressive lineationsshow that the Neogene extensional regime of the Crotone basin was punctuated by compressive episodes.Finally, compressive lineations (prolate magnetic fabric) documented along the strike-slip fault boundingthe basin to the south support the significance of Pleistocene strike-slip tectonics. Thus the Crotone basinshows a markedly different tectonics with respect to other internal and western basins of Calabria, asit yields a magnetic fabric still dominated by extensional tectonics but also revealing arc-normal short-ening episodes and recent strike-slip fault activity. The tectonics documented in the Crotone basin iscompatible with a continuous upper crustal structural reorganization occurring during the SE-migrationof the Calabria terrane above the Ionian subduction system.
    Description: Published
    Description: 67-79
    Description: 1A. Geomagnetismo e Paleomagnetismo
    Description: JCR Journal
    Description: restricted
    Keywords: Calabrian Arc, Anisotropy of magnetic susceptibility, Structural analysis, Fore-arc region ; 04. Solid Earth::04.04. Geology::04.04.08. Sediments: dating, processes, transport ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism ; 04. Solid Earth::04.05. Geomagnetism::04.05.07. Rock magnetism ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 97
    Publication Date: 2021-01-25
    Description: The Late Pleistocene Albano Maar hosted the most recent volcanic activity of the Colli Albani Volcanic District, represented at nearvent sections by a thick pyroclastic succession of seven units clustered in two main eruptive cycles dated at around 70–68 and 41–36 ka B.P., respectively. Recent stratigraphic investigations allowed us to recognise a pyroclastic succession comprising four eruptive units widely spread in the northeastern sectors of the Colli Albani volcano, up to 15km eastward from the Albano Maar. Integrated tephrostratigraphic, morpho-pedostratigraphic, archaeological, petrological and geochemical analyses enable us to recognise them as distal deposits of the first, third, fifth and seventh Albano Maar eruptions, enlarging significantly their previously supposed dispersion area. Further tephrostratigraphic studies in central Apennine area, allowed us to identify the Albano Maar products in Late Pleistocene deposits of several intermountain basins, extending still further the dispersion area of distal ash fallout as far as 100–120km from the vent. On the basis of the identification and the study of these previously unrecognised mid-distal Albano Maar deposits, a reappraisal of the eruptive scenarios and related energetic parameters is proposed.
    Description: Published
    Description: 160–178
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: JCR Journal
    Description: reserved
    Keywords: Colli Albani ; Albano ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 98
    Publication Date: 2021-01-27
    Description: Na–HCO3–CO2-rich thermomineral waters issue in the N of Portugal, within the Galicia-Trás-os-Montes region, linked to a major NNE-trending fault, the so-called Penacova-Régua-Verin megalineament. Along this tectonic structure different occurrences of CO2-rich thermomineral waters are found: Chaves hot waters (67 °C) and also several cold (16.1 °C) CO2-rich waters. The δ2H and δ18O values of the thermomineral waters are similar to those of the local meteoric waters. The chemical composition of both hot and cold mineral waters suggests that water–rock reactions are mainly controlled by the amount of dissolved CO2 (g) rather than by the water temperature. Stable carbon isotope data indicate an external CO2 inorganic origin for the gas. δ13CCO2 values ranging between −7.2‰ and −5.1‰ are consistent with a two-component mixture between crustal and mantle-derived CO2. Such an assumption is supported by the 3He/4He ratios measured in the gas phase, are between 0.89 and 2.68 times the atmospheric ratio (Ra). These ratios which are higher than that those expected for a pure crustal origin (≈0.02 Ra), indicating that 10 to 30% of the He has originated from the upper mantle. Release of deep-seated fluids having a mantle-derived component in a region without recent volcanic activity indicates that extensive neo-tectonic structures originating during the Alpine Orogeny are still active (i.e., the Chaves Depression).
    Description: Published
    Description: 49-56
    Description: 4.5. Studi sul degassamento naturale e sui gas petroliferi
    Description: JCR Journal
    Description: reserved
    Keywords: CO2-rich thermomineral waters ; mantle volatiles ; isotopes ; Chaves geothermal system ; N-Portugal ; 03. Hydrosphere::03.02. Hydrology::03.02.02. Hydrological processes: interaction, transport, dynamics ; 03. Hydrosphere::03.02. Hydrology::03.02.03. Groundwater processes ; 03. Hydrosphere::03.04. Chemical and biological::03.04.03. Chemistry of waters ; 03. Hydrosphere::03.04. Chemical and biological::03.04.06. Hydrothermal systems ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 99
    Publication Date: 2021-04-07
    Description: The Colfiorito Mw 6.0 (September 26, 1997, 09:40 UTC) and the Sellano Mw 5.6 (October 14, 1997) normal faulting earthquakes are the two strongest events of the 1997–1998 Umbria–Marche seismic sequence (central Italy). They provided accelerograms recorded at epicentral distances within nearly two fault lengths. Previous studies on these events revealed clear evidence of unilateral rupture propagation and directivity effects on the source time functions We developed an approximate procedure to correct the observed peak ground motion for the site effects, and we found a systematic increase of peak ground acceleration (PGA) and peak ground velocity (PGV) at sites located in the direction of the rupture propagation respect to the stations located to the backward. In particularwe showed that, for the Colfiorito earthquake, the average PGV at the north-west sites is 2.8 times larger than the PGV at south-east sites (2.1 for PGA); an opposite behaviour is found during the Sellano earthquake, with an amplification factor of about 1.9 for PGV (1.5 for PGA) recorded at south-east sites respect to the north-west stations.We explained these behaviours in terms of directivity effect, by comparing recorded ground accelerations with synthetics simulated by a deterministic–stochastic technique. This method computes high-frequency ground motions (fN0.5 Hz) from extended faults, generalizing the point-source stochastic method to capture the essence of near-source effects. The synthetic PGAs decrease with distance in agreement with the ground-motion empirical predictive model available for the area and describe the azimuthal variation of recorded data in terms of source effects.
    Description: Published
    Description: 110-120
    Description: 4.1. Metodologie sismologiche per l'ingegneria sismica
    Description: JCR Journal
    Description: reserved
    Keywords: Directivity effects ; Umbria-Marche seismic sequence ; 04. Solid Earth::04.06. Seismology::04.06.04. Ground motion
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 100
    Publication Date: 2021-04-07
    Description: Degassing activity from marine shallow-water hydrothermal vents represents a natural important source of trace elements of particular ecotoxicological concern, such as Hg, Cd, Pb, and As. In 2002, on November 3rd, a submarine area of the Aeolian Archipelago (Italy) was affected by an exceptional hydrothermal activity, presumably associated to a significant trace element release. This study developed in the highest impacted area, was focused on different environmental matrices (water, sediment, primary producers, and fishes) with the aim to evaluate on a statistical basis temporal dynamics involving trace elements closed to the emission source. Results evidenced that this event produced significant changes in water column, modifying the general assessment of the chemical descriptors selected (Na, K, Mg, Ca, Cl, Br, SO4 2-, HCO3 -). Furthermore, the degassing activity represents a significant input of Hg, Cd, Pb, and As for all of the sampled matrices, being it responsible of the higher levels observed in the study area compared to controls. Concentrations measured in sediments and biota (Cystoseira compressa, Serranus cabrilla) at temporal intervals of ten months distanced, supported the occurrence of different time scale dynamics which are both element and matrix-dependent. In particular, levels of Cd and As measured in liver tissues of S. cabrilla evidenced a significant trend to increase with the time, allowing to exclude a quick recovery of the study area. Measured values in edible fishes tissues are, also, notably higher than risk limits proposed by the 2001/22/CE Directive for human consumption, so, local-based caught have to be accurately regulated to avoid the occurrence of diet over-exposure.
    Description: Published
    Description: 10-28
    Description: 1.8. Osservazioni di geofisica ambientale
    Description: N/A or not JCR
    Description: restricted
    Keywords: trace elements ; hydrothermal vents ; 03. Hydrosphere::03.04. Chemical and biological::03.04.06. Hydrothermal systems
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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