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REPORT TECNICO: SISMICITÀ DEL VESUVIO NEGLI ANNI 1972-2024
No full textIl Monte Vesuvio è un vulcano attivo situato nella pianura campana, caratterizzato da
un'intensa attività eruttiva negli ultimi 25.000 anni. Attualmente, il vulcano si trova in una fase
di quiescenza dal 1944, con un'attività sismica moderata prevalentemente superficiale. Questo
report analizza l'evoluzione della sismicità vesuviana negli ultimi cinquant'anni, con particolare
attenzione agli aspetti tecnici della pre-analisi dei dati sismici e alla loro evoluzione storica.Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Napoli - Osservatorio VesuvianoPublishe
APPLICATION OF EMR METHOD TO RETRIEVE THE VELOCITY STRUCTURES IN THE AMATRICE AREA, CENTRAL ITALY
No full texthttps://proceedings-wcee.org/view.html?id=25585&conference=18WCEEDetailed reconstruction of the velocity structure at a site using an appropriate method is a key element for site amplification evaluation. However, earthquake observation requires long-lasting seismic recording periods and more costly than microtremor observation. To estimate the velocity structures from the surface down to the seismological bedrock, Kawase et al. (2018) proposed a novel method to calculate pseudo earthquake horizontal-to-vertical spectral ratio (pEHVR) from horizontal-to-vertical spectral ratios of microtremors (MHVR) and EMR, which is the averaged spectral amplitude ratio between EHVR and MHVR obtained at the same site. They calculated EMRs at one hundred sites in Japan which were classified into 5 classes based on their fundamental peak frequencies in MHVR and then averaged EMR data in each class. Thus, pEHVR can be calculated at any site by correcting available MHVR for the average EMR to which the site belongs. They found that pEHVR is much closer to EHVR than MHVR and that pEHVR can be effectively used as an inversion target to estimate velocity structure; the obtained velocity structures from the inversion code based on the diffuse field concept (Nagashima et al., 2014) are more similar to those obtained by EHVR inversion in comparison to those retrieved by MHVR inversion. However, when applying this method to the data in other countries, EMR calculated in Japan may not be directly applicable, because EMR should be a function of the velocity structures from the bedrock to the surface, the average of which may not be the same across different countries. As an extension of this EMR method outside Japan, Ito et al. (2021) calculated local EMR for the Grenoble basin in France delineating the velocity structures inside the basin with a good match with the previous study. In this study, focusing on Amatrice village, Italy, where many historical buildings were totally damaged by the August 2016 Central Italy earthquake, we calculate EMR specific for this area (EMRA) using the observed earthquake and microtremor recordings at seven sites. We found that EMRA is almost unity for a wide frequency range, which may be due to the specific geological setting of the area. Then, we calculate a pEHVR by multiplying the obtained EMRA with MHVR and get the inverted velocity structure using the pEHVR based on the diffuse field theory. The applicability of EMR method to another area in Italy is also discussed.Publishe
Near field tsunamis on volcanic islands: blueprint for risk management using Stromboli as a test bed
No full textAt Stromboli, coastline populations are exposed to near-field tsunami generated by flank collapses.
Landslides on the Sciara del Fuoco can generate waves arriving in the village in less than a few
minutes. Due to the hazard posed on Stromboli by tsunami, we have focused our research on
answering three key questions in terms of mitigation: (1) How can a tsunami be detected and
characterized in real-time? (2) What will be the likely event scenario and on-island impact of the
resulting tsunami? (3) When and where will the tsunami arrive, and what is the evacuation capacity?
To this end, we have convolved a method to assess escape times from tsunami-exposed coastal areas,
with wave travel times and inundation assessments output from numerical simulations. Here we
review the local situation in terms of hazard, risk and mitigation measures, and assess progress to
date in preparing for tsunami on Stromboli to explore a blueprint for management actions at any
near-field tsunami-exposed communityPublishedJCR Journa
Statistical models of the variability of plasma in the topside ionosphere: 1. Development and optimisation
No full textThis work presents statistical models of the variability of plasma in the topside ionosphere based on observations made by the European Space Agency's (ESA) Swarm satellites. The models were developed in the "Swarm Variability of Ionospheric Plasma" (Swarm-VIP) project within the European Space Agency's Swarm+4D-Ionosphere framework. The configuration of the Swarm satellites, their near-polar orbits and the data products developed, enable studies of the spatial variability of the ionosphere at multiple scale sizes. The statistical modelling technique of Generalised Linear Modelling (GLM) was used to create models of both the electron density and measures of the variability of the plasma structures at horizontal spatial scales between 20 km and 100 km. Despite being developed using the Swarm data, the models provide predictions that are independent of these data. Separate models were created for low, middle, auroral and polar latitudes. The models make predictions based on heliogeophysical variables, which act as proxies for the solar and geomagnetic processes. The first and most significant term in the majority of the models was a proxy for solar activity. The most common second term varied with the latitudinal region. This was the Solar Zenith Angle (SZA) in the polar region, a measure of latitude in the auroral region, solar time in the mid-latitude region and a measure of latitude in the equatorial region. Other, less significant terms in the models covered a range of proxies for the solar wind, geomagnetic activity and location. In this paper, the formulation, optimisation and evaluation of these models are discussed. The models show very little bias, with a mean error of zero to two decimal places in 14 out of 20 cases. The models capture some, but not all, of the trends present in the data, with Pearson correlation coefficients of up to 0.75 between the observations and the model predictions. The models also capture some, but not all, of the variability of the ionospheric plasma, as indicated by the precision, which ranged between 0.20 and 0.83. The addition of the thermospheric density as an explanatory variable in the models improved the precision in the polar and auroral regions. It is suggested that, if the thermosphere could be observed at a higher spatial resolution, then even more of the variability of the plasma structures could be captured by statistical models. The formulation and optimisation of the models are presented in this paper. The capability of the model in reproducing the expected climatological features of the topside ionosphere, in supporting GNSS-based ionospheric observations and the performance of the model against the Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIE-GCM), are provided in a companion paper (Spogli L et al. 2024.PublishedJCR Journa
Mechanically Consistent Model of the 2018 Christmas Volcano-Tectonic Event at Etna
No full textThe interaction between volcanic activity and flank instability during the Christmas Eve eruption at Mount Etna in 2018 is explored, using a mechanically consistent inverse model fitting high spatial resolution SAR data. Inversions search for fractures that may be curved and can accommodate co-eval pressure and shear stress changes. Displacements associated with the eruption result from the interaction between two intrusion sources: a buried dyke and a curved sheared intrusion that fed the eruption. Moreover, we identify that the sheared magmatic intrusion induced the observed eastward slip on the Pernicana fault, while the Fiandaca fault was undergoing stress accumulation, which was suddenly released during a M5.0 seismic event. The Fiandaca fault is determined to be listric, rooting beneath the mobile eastern flank of the volcano. This study highlights the role of curved fractures, acting as sheared intrusions or as faults, in volcanoes exhibiting flank instabilities. In this study, we thoroughly examine how volcanic activity and flank dynamics interacted during the 2018 eruption of Mount Etna. We use high-resolution satellite SAR data and a model considering complex mechanical aspects of the volcano's behavior. Formal inversions reveal that the eruption is triggered by the interplay between two intrusion sources: a buried dyke and a curved sheared intrusion, consistent with the earthquake pattern. This study emphasizes the significant role of curved sheared intrusions and faults at volcanoes prone to flank instabilities. Furthermore, we quantify how summit magmatic intrusions promote fault slip in the eastern flank of Etna. These findings differ from previous research that used simpler approaches. In summary, our study provides a new insight into how volcanoes like Etna can erupt and trigger flank slip, shedding light on the complex interactions between magma and tectonics.PublishedJCR Journa
Cement vs aggregates and textures of aggregates in a mortar: Comparative image analysis methods and analytical protocols
No full textThe types, abundance and texture of phases are crucial for reconstructing the manufacturing of historical and
contemporary construction materials such as mortars. Commonly, these data are obtained on polished mesoscopic
and/or thin section surfaces and imaged with several techniques. Here, a thin section from an already
well-characterised mortar was analysed to unveil the amount (area%) of cement paste vs aggregates, plus the
textural features of the aggregates. The thin section was imaged by a high-resolution scanner (HRS), by transmission
optical microscopy (TOM) and scanning electron microscopy (SEM). The single HRS image discriminates
only quartz (qz) from cement+af+ss (af: alkali-feldspar, ss: sheetsilicates). The stitched TOM image distinguishes
cement from aggregates, i.e. qz+af+ss, whereas the stitched SEM image discriminates cement, pores, qz and
af+ss. The amount of cement vs aggregates and the area of the different aggregates determined by SEM is more
accurate since it reflects chemical attributes. 2D Fuller curves were constructed considering different types of 2D
dimensional parameters extracted from both TOM and SEM digital images. Intermediate dimensional parameters
for both TOM and SEM had the best match with the 3D sieving Fuller curve. SEM shows the most detailed and
adaptable recognition of cement to aggregate ratio and quantification of aggregate clasts, but it is timeconsuming
and expensive. HRS is rapid but only crudely accurate. TOM is more accurate and less expedite
than HRS; by contrast, TOM is faster than SEM but unable to distinguish different aggregate clasts with similar
optical features.Published139033JCR Journa
An Integrated Petrographic, Geomatic and Geophysical Approach for the Characterization of the Carbonate Rocks of the Calcari di Cagliari Formation
No full textAbstract: Non-invasive techniques, such as close-range photogrammetry (CRP) and 3D ultrasonic
tomography complemented with optical and scanning electron microscopy and mercury porosimetry,
were applied to characterize the carbonate rock samples of the Calcari di Cagliari formation. The integrated
approach started with the computation of high-resolution 3D models of the carbonate samples
using the CRP technique to produce 3D high-resolution models texturized both with natural colors
and intensity. Starting from the 3D models from previous techniques, a 3D ultrasonic tomography on
each rock sample was accurately planned and carried out in order to detect the elastic properties of
such rocks and relate them to textural heterogeneity or internal defects. The results indicate that the
relationship between longitudinal velocity and rock properties is complex even in the same carbonate
formation. Understanding the relationship between the geomatic and geophysical responses in the
investigated rock properties, such as textural characteristics and especially structure and geometry of
pores, type of pores, tortuosity and cementing material, is important for many practical applications
and especially in the diagnostic process of the conservation state of monumental structures. The
integration of the above non-invasive techniques complemented by petrographical–petrophysical
data proved to be a powerful method to associate each lithotype with a different susceptibility to
degradation. The results presented in this paper demonstrate that the proposed integrated use of
complementary methodologies would guarantee the reproducibility of the measurements both at
the laboratory and field scale for the monitoring in time of the rock condition while giving a useful
contribution in making decisions on an appropriate remedial strategy.Published501OSA5: Energia e georisorseJCR Journa
Tremors-A Software App for the Analysis of the Completeness Magnitude
No full textThis article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BYPublished149JCR Journa
Perpendicular Electrical Conductivity in the Topside Ionosphere Derived from Swarm Measurements
No full textThe study of the physical properties of the topside ionosphere is fundamental to investigating the energy balance of the ionosphere and developing accurate models to predict relevant phenomena, which are often at the root of Space Weather effects in the near-Earth environment. One of the most important physical parameters characterising the ionospheric medium is electrical conductivity, which is crucial for the onset and amplification of ionospheric currents and for calculating the power density dissipated by such currents. We characterise, for the first time, electrical conductivity in the direction perpendicular to the geomagnetic field, namely Pedersen and Hall conductivities, in the topside ionosphere at an altitude of about 450 km. For this purpose, we use eight years of in situ simultaneous measurements of electron density, electron temperature and geomagnetic field strength acquired by the Swarm A satellite. We present global statistical maps of perpendicular electrical conductivity and study their variations depending on magnetic latitude and local time, seasons, and solar activity. Our findings indicate that the most prominent features of perpendicular electrical
conductivity are located at low latitudes and are probably driven by the complex dynamics of the Equatorial Ionisation Anomaly. At higher latitudes, perpendicular conductivity is a few orders of magnitude lower than that at low latitudes. Nevertheless, conductivity features are modulated by solar activity and seasonal variations at all latitudes.Published3129OSA3: Climatologia e meteorologia spazialeJCR Journa
The pre-Campi Flegrei caldera (>40 ka) explosive volcanic record in the Neapolitan Volcanic Area: New insights from a scientific drilling north of Naples, southern Italy
No full textThe oldest volcanism documented in near-vent sections around the Campi Flegrei (CF, southern Italy) caldera does not exceed ∼78 ka, even though the mid- to ultra-distal tephrostratigraphic record would suggest that activity in this area started well before that. Reconstructing the activity preceding the large caldera-forming Campanian Ignimbrite (CI) eruption of ∼40 ka, via surface geological surveys in proximal areas, is challenging because of the poor accessibility and paucity of sections recording the older chronostratigraphic interval. In order to fill the gap in knowledge of the activity preceding the CI eruption, a 113.2 m deep scientific drillhole was emplaced in the Ponti Rossi area, in the northern part of the city of Naples. The Ponti Rossi area was selected as representative of the stratigraphic setting prior to the CF caldera formation because it is close, although external, to any proposed caldera rim or downthrown area. The cored succession, consisting of pyroclastic deposits separated by paleosols, reworked humified deposits or subaerial erosional surfaces, has been logged and sampled for sedimentological, mineralogical, and geochronological analyses. Thirty-one Pyroclastic Units (PU) were identified. Based on the structural/textural features of the recovered sediments, the first relevant result is the possible absence of the CI, while the deposits of the ∼15 ka Neapolitan Yellow Tuff eruption, the second largest caldera-forming event of CF, represent the shallowest sediments. 40Ar/39Ar age determinations on alkali feldspars, extracted from juvenile fragments collected at 45.8–45.9 (PU-29) and 99.5–99.6 (PU-1) metres of depth, yielded ages of 59.03±0.50 ka and 110.00±0.35 ka, respectively. The age obtained for the deepest cored unit, having sedimentological characteristics compatible with proximal deposition, represents the oldest age obtained for a pyroclastic deposit in the sequences near the CF caldera boundaries and extends by 30 ky the explosive history of this area. Furthermore, based on 40Ar/39Ar age constraints, at least 29 eruptions, spanning the ∼59–110 ka interval, can be added to the volcanic history of the Neapolitan Volcanic Area. These eruptions can be largely attributed to the CF area, prior to the CI caldera formation, and testify to hitherto unknown, intense explosive activity.Published108209JCR Journa