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  • Articles  (9)
  • 04.08. Volcanology  (5)
  • 04.04. Geology  (2)
  • 04.05. Geomagnetism  (2)
  • Wiley Agu  (8)
  • American Association for the Advancement of Science
  • American Meteorological Society
  • American Physical Society
  • Frontiers Media
  • Institute of Physics
  • Springer Nature
  • Springer Science + Business Media
  • 2020-2022  (9)
  • 2005-2009
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  • Articles  (9)
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  • 1
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    On the Multifractal Features of Low‐Frequency Magnetic Field Fluctuations in the Field‐Aligned Current Ionospheric Polar Regions: Swarm Observations (2020)
    Wiley Agu
    Details
    Publication Date: 2020-11-19
    Description: Recent findings on the nature of magnetic field fluctuations in the high-latitude ionospheric regions have suggested the existence of scaling features, which are the signature of the occurrence of turbulence. These features mainly characterize the magnetic field fluctuations in those regions where the field-aligned currents flow. Here, we investigate the nature of the Earth's magnetic field fluctuations using the high-resolution (50 Hz) magnetic measurements from the European Space Agency Earth's observation mission Swarm. Our study indicates that spatiotemporal anomalous scaling features characterize low-frequency magnetic field fluctuations in the high-latitude ionospheric regions of field-aligned currents at spatial scales in the range 0.8–80 km (timescales in the range 0.1–10 s). The signature of a multifractal nature of these fluctuations suggests a highly complex structure of the field-aligned currents. Our results support the view of inhomogeneous (filamentary) field-aligned currents, which can have relevant implications in the comprehension of the physical processes responsible for the magnetospheric-ionospheric coupling and ionospheric heating.
    Description: ESA Contract No. 4000125663/18/I-NB (INTENS)
    Description: Published
    Description: e2019JA027429
    Description: 1A. Geomagnetismo e Paleomagnetismo
    Description: JCR Journal
    Keywords: field-aligned currents ; scaling properties ; 04.05. Geomagnetism ; 01.02. Ionosphere
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
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    The location of the Earth's magnetic poles from circum‐terrestrial observations (2021)
    Wiley Agu
    Details
    Publication Date: 2021-02-23
    Description: The magnetic poles or dip poles are the points on the Earth's surface and circum‐terrestrial area where the magnetic field is vertical, so the horizontal component vanishes. They are not coincident with geomagnetic poles, which are the points where the dipole axis, obtained by analytic models, intersects the Earth's surface, and their instrumental sampling determination from ad hoc ground surveys is difficult due to the harsh environmental conditions and remoteness of the areas where they are located. In this work, we use magnetic field measurements from ESA's Swarm satellites covering 5 years (2015‐2019), and determine the position of the magnetic poles by modelling the yearly average horizontal magnetic field component through analytic 2D Taylor polynomial fit and finding the locations where this component is minimum. The yearly dip poles positions at average satellites geocentric altitudes are also projected at ground level based on WGS84 geodetic reference system. Reliability of our method is evaluated by an optimized Monte Carlo test applied to combined IGRF model and Swarm data. The availability of several years of data allows us to investigate the long term variation and dynamics of the magnetic poles, also in comparison with the results provided by IGRF model (both IGRF12 and IGRF13). Our results agree with the model, in better accordance in the north hemisphere with IGRF13, indicating that both magnetic poles move in the north‐west direction, with a speed of ∼37‐72 km/y (lower in year 2016) for the north dip pole and of ∼5‐9 km/y for the south one.
    Description: Published
    Description: e2020JA028513
    Description: 1A. Geomagnetismo e Paleomagnetismo
    Description: JCR Journal
    Keywords: Magnetic poles location ; Swarm satellites ; Magnetic poles drift ; Magnetic anomalies ; Antarctic and Arctic polar regions ; Monte Carlo test ; 04.05. Geomagnetism ; 05.01. Computational geophysics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 3
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    A Large Paleoearthquake in the Central Apennines, Italy, Recorded by the Collapse of a Cave Speleothem (2021)
    Wiley Agu
    Details
    Publication Date: 2021-05-12
    Description: Speleoseismological research carried out in the Central Apennines (Italy) contributed to understanding the behavior of active normal faults that are potentially able to generate Mw 6.5–7 earthquakes documented by paleoseismology and by historical and instrumental seismology. Radiometric (U‐Th, AMS‐14C, and bulk‐14C) dating of predeformation and postdeformation layers from collapsed speleothems found in Cola Cave indicates that at least three speleoseismic events occurred in the cave during the last ~12.5 ka and were ostensibly caused by seismic slip on one or more of the active faults located in the region surrounding the cave. We modeled the collapse of a tall (173 cm high) stalagmite to find a causative association of this event with one among the potential seismogenic sources. We defined the uniform hazard spectrum (UHS) for each seismogenic source at the site, and we used the calculated spectra in a deterministic approach to study the behavior of the speleothem, through a numerical finite element modeling (FEM). Although our analysis suggests the “Liri” fault as the most likely source responsible for the ground shaking recorded in the cave, the “Fucino” fault system, responsible for a Mw 7 earthquake in 1915, cannot be excluded as a potential source of speleoseismic damage. Results of this work provide new constraints on the seismotectonic history of this sector of Central Apennines and highlight the performance of integrated speleoseismological, seismic hazard, and numerical studies.
    Description: Published
    Description: e2020TC006289
    Description: 6T. Studi di pericolosità sismica e da maremoto
    Description: JCR Journal
    Keywords: Speleoseismology ; Central Apennines ; seismic hazard ; finite element modeling ; 04.04. Geology ; 04.06. Seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 4
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    Effusion Rate Evolution During Small‐Volume Basaltic Eruptions: Insights From Numerical Modeling (2020)
    Wiley Agu
    Details
    Publication Date: 2020-10-16
    Description: The temporal evolution of effusion rate is the main controlling factor of lava spreading and emplacement conditions. Therefore, it represents the most relevant parameter for characterizing the dynamics of effusive eruptions and thus for assessing the volcanic hazard associated with this type of volcanism. Since the effusion rate curves can provide important insights into the properties of the magma feeding system, several efforts have been performed for their classification and interpretation. Here, a recently published numerical model is employed for studying the effects of magma source and feeding dike properties on the main characteristics (e.g., duration, erupted mass, and effusion rate trend) of small‐volume effusive eruptions, in the absence of syn‐eruptive magma injection from deeper storages. We show that the total erupted mass is mainly controlled by magma reservoir conditions (i.e., dimensions and overpressure) prior to the eruption, whereas conduit processes along with reservoir properties can significantly affect mean effusion rate, and thus, they dramatically influence eruption duration. Simulations reproduce a wide variety of effusion rate trends, whose occurrence is controlled by the complex competition between conduit enlargement and overpressure decrease due to magma withdrawal. These effusion rate curves were classified in four groups, which were associated with the different types described in the literature. Results agree with the traditional explanation of effusion rate curves and provide new insights for interpreting them, highlighting the importance of magma reservoir size, initial overpressure, and initial width of the feeding dike in controlling the nature of the resulting effusion rate curve.
    Description: Published
    Description: e2019JB01930
    Description: 5V. Processi eruttivi e post-eruttivi
    Description: JCR Journal
    Keywords: effusive eruption ; basaltic eruptions ; numerical modeling ; 04.08. Volcanology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 5
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    Tree‐Branching‐Based Enhancement of Kinetic Energy Models for Reproducing Channelization Processes of Pyroclastic Density Currents (2020)
    Wiley Agu
    Details
    Publication Date: 2020-10-16
    Description: Kinetic energy models, also called kinetic models, are simple tools able to provide a fast estimate of the inundation area of pyroclastic density currents (PDCs). They are based on the calculation of the PDC front kinetic energy as a function of the distance from a source point. On a three‐dimensional topography, the PDC runout distance is estimated by comparing the flow kinetic energy with the potential energy associated with the topographic obstacles encountered by the PDC. Since kinetic models do not consider the occurrence of channelization processes, the modeled inundation areas can be significantly different from those observed in real deposits. To address this point, we present a new strategy that allows improving kinetic models by considering flow channelization processes, and consists in the inclusion of secondary source points in the expected channelization zones, adopting a tree branch‐like structure. This strategy is based on the redistribution of a key physical variable, such as the flow energy or mass depending on the considered kinetic model, and requires the adoption of appropriate equations for setting the characteristics of the secondary sources. Two models were modified by applying this strategy: the energy cone and the box model. We tested these branching models by comparing their results with those derived from their traditional formulations and from a two‐dimensional depth‐averaged model, considering two specific volcanoes (Chaitén and Citlaltépetl). Thereby, we show the capability of this strategy of improving the accuracy of kinetic models and considering flow channelization processes without including additional, unconstrained input parameters.
    Description: Published
    Description: e2019JB019271
    Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio
    Description: JCR Journal
    Keywords: Pyroclastic Density Currents ; Numerical Modeling ; 04.08. Volcanology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 6
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    Radon Activity in Volcanic Gases of Mt. Etna by Passive Dosimetry (2021)
    Wiley Agu
    Details
    Publication Date: 2021-01-07
    Description: Radon (222Rn) activity in air was measured for about 6 months at the summit of Mt. Etna Central Crater (Sicily) by integrative radon dosimetry at two different heights above ground level (5 cm and 1 m). This technique for air radon monitoring proved operational in the harsh volcanic environment of Mt. Etna summit with a 94% recovery rate of dosimeters. In the southeast sector exposed to the main gas plume, mean radon activity in free air (height 1 m) is significantly higher than the local background and the ground level activity (height 5 cm). The results strongly suggest that the plume is enriched in radon by ≈550 Bq/m3, which has never been evidenced before. Radon activities also reflect soil degassing occurring in the proximity of the crater, with increased ground level activities in zones of enhanced soil fracturing and degassing. Radon measurements also revealed a hot spot in front of the Voragine vent with extraordinary high levels of air activities (26 kBq/m3 at ground level and 8 kBq/m3 in free air). The temporal variation of radon activity was investigated by replacing a few stations half way through the exposure period. The only significant increase was associated with the site located under the main gas plume and correlated with eruptive unrest within the crater. Finally, air radon levels higher than the recommended threshold of 300 Bq/m3 were detected in several zones on the rim and could generate a nonnegligible radiologic dose for workers on the volcano.
    Description: Published
    Description: e2019JB019149
    Description: 3V. Proprietà chimico-fisiche dei magmi e dei prodotti vulcanici
    Description: JCR Journal
    Keywords: 04.08. Volcanology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 7
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    Combined Seismic and Geodetic Analysis Before, During, and After the 2018 Mount Etna Eruption (2021)
    Wiley Agu
    Details
    Publication Date: 2021-01-05
    Description: In December 2018, Etna volcano experienced one of the largest episodes of unrest since the installation of geophysical monitoring networks in 1970. The unrest culminated in a short eruption with a small volume of lava erupted, a significant seismic crisis and deformation of the entire volcanic edifice of magnitude never recorded before at Mount Etna. Here we describe the evolution of the 2018 eruptive cycle from the analysis of seismic and geodetic data collected in the months preceding, during, and following the intrusion. We model the space‐time evolution of high‐rate deformation data starting from the active source previously identified from deformation data and the propagation of seismicity in a 3‐D velocity model. The intrusion model suggests emplacement of two dikes: a smaller dike located beneath the eruptive fissure and a second, deeper dike between 1 and 5 kmbelow sea level that opened ~2 m. The rise and eruption of magma from the shallower dike did not interrupt the pressurization of a long‐lasting deeper reservoir (~6 km) that induced continuous inflation and intense deformation of the eastern flank. Shortly after the intrusion, on 26 December 2018, aML4.8 earthquake occurred near Pisano, destroying buildings and roads in two villages. We propose a time‐dependent intrusion model that supports the hypothesis of the inflation inducing flank deformation and that this process has been active since September 2018.
    Description: Published
    Description: e2020GC009218
    Description: 2V. Struttura e sistema di alimentazione dei vulcani
    Description: JCR Journal
    Keywords: 2018 Mount Etna Eruption, time‐dependent intrusion model, modelling of high‐rate deformations ; 04.08. Volcanology ; 04.03. Geodesy ; 04.06. Seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 8
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    Quantifying the Uncertainty of a Coupled Plume and Tephra Dispersal Model: PLUME‐MOM/HYSPLIT Simulations Applied to Andean Volcanoes (2020)
    Wiley Agu
    Details
    Publication Date: 2021-06-16
    Description: Numerical modeling of tephra dispersal and deposition is essential for evaluation of volcanic hazards. Many models consider reasonable physical approximations in order to reduce computational times, but this may introduce a certain degree of uncertainty in the simulation outputs. The important step of uncertainty quantification is dealt in this paper with respect to a coupled version of a plume model (PLUME‐MoM) and a tephra dispersal model (HYSPLIT). The performances of this model are evaluated through simulations of four past eruptions of different magnitudes and styles from three Andean volcanoes, and the uncertainty is quantified by evaluating the differences between modeled and observed data of plume height (at different time steps above the vent) as well as mass loading and grain size at given stratigraphic sections. Different meteorological data sets were also tested and had a sensible influence on the model outputs. Other results highlight that the model tends to underestimate plume heights while overestimating mass loading values, especially for higher‐magnitude eruptions. Moreover, the advective part of HYSPLIT seems to work more efficiently than the diffusive part. Finally, though the coupled PLUME‐MoM/HYSPLIT model generally is less efficient in reproducing deposit grain sizes, we propose that it may be used for hazard map production for higher‐magnitude eruptions (sub‐Plinian or Plinian) for what concern mass loading.
    Description: This research was financed by the French government IDEX‐ISITE initiative 16‐IDEX‐0001 (CAP 20‐25), the Institute de Recherche pour le Développement (IRD) in the context of the Laboratoire Mixte International “Séismes et Volcans dans les Andes du Nord” (SVAN), and the Centre National de la Recherche Scientifique (CNRS) Tellus programme.
    Description: Published
    Description: e2019JB018390
    Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio
    Description: JCR Journal
    Keywords: Tephra deposit ; 04.08. Volcanology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 9
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    Deep carbon degassing in the Matese massif chain (Southern Italy) inferred by geochemical and isotopic data (2021)
    Springer Nature
    Details
    Publication Date: 2021-09-22
    Description: The Italian Apennines are among the most important sources of freshwater for several Italian regions. With evidences of deep CO2-rich fluids intruding into aquifers in the nearby central-southern Apennines, a thorough investigation into the geochemistry of groundwater became critical to ensure the water quality in the area. Here, we show the main hydrogeochemical processes occurring in the Matese Massif (MM) aquifer through the investigation of 98 water samples collected from springs and water wells. All waters were classified as HCO3 type with Ca dominance (from 50% up to 97%) and variable amount of Mg (from 1% up to 49%). A multivariate statistical approach through the application of the factor analysis (FA) highlighted three main hydrogeochemical processes: (i) water-carbonate rock interactions mostly enhanced in peripheral areas of the MM by CO2 deep degassing; (ii) addition of NaCl-rich components linked to recharging process and to water mixing processes of the groundwater with a thermal component relatively rich in Cl, Na, and CO2; (iii) anthropogenic activities influencing groundwater composition at the foothills of MM. Furthermore, the first detailed TDIC, pCO2, and δ13C-TDIC distribution maps of the MM area have been created, which track chemical and isotopic anomalies in several peripheral areas (Pratella, Ailano, and Telese) throughout the region. These maps systematically highlight that the greater the amount of dissolved carbon occurs the heavier the C isotope enrichment, especially in the peripheral areas. Conversely, spring waters emerging at higher altitudes within MM are only slightly mineralized and associated with δ13C-TDIC values mainly characterized by recharging processes with the addition of biogenic carbon during the infiltration process through the soil.
    Description: Published
    Description: 46614–46626
    Description: 6A. Geochimica per l'ambiente e geologia medica
    Description: 2IT. Laboratori analitici e sperimentali
    Description: JCR Journal
    Keywords: CO2 degassing; Factor analysis; Mineral springs; Total dissolved inorganic carbon; δ13C-TDIC ; 03.02. Hydrology ; 04.04. Geology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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