OA Earth-prints Repository
Not a member yet
16457 research outputs found
Sort by
Quaternary Evolution of Ischia: A Review of Volcanology and Geology
No full textIschia shows intriguing and complex geology, which has been deeply investigated. In
this paper, a reappraisal of the Quaternary geologic evolution of Ischia based on literature data is
advised, concentrating on the volcanology of the island, based on field data and geochemistry, due
to the happening of active fumarolic systems on the island and the marine geology and geophysics,
which are intensively studied in the frame of the CARG Project. The literature studies have been
incorporated with the geological interpretation of high-resolution seismic profiles, partly previously
published and herein reorganized with the aim to highlight the geologic evolution of the different
sectors of the island (northern Ischia, southern Ischia). The outcrop data have shown the deposits
of ten explosive eruptions: among them, we focused on the S. Angelo Tephra. The laccolith model
has been described in order to explain the resurgence of Ischia starting from 55 ky B.P. Geochemical
information has been synthesized to reconstruct the volcano-tectonic development of Ischia during
the last 55 ky B.P. Different models of block resurgence of Ischia have been discussed, based on
literature studies. These aspects have supplemented the Quaternary geologic evolution of Ischia.
While the northern Ischia offshore shows complex stratigraphic relationships between buried volcanic
edifices, the southern Ischia offshore has been mainly commanded by erosional activities, progressive
next to a dense system of submarine channels, and by the volcano-tectonic activities, which have
triggered off the location of the Ischia Debris Avalanche.Published35541T. Struttura della TerraJCR Journa
Chaos and Predictability in Ionospheric Time Series
No full textModelling the Earth's ionosphere is a big challenge, due to the complexity of the system. Different first principle models have been developed over the last 50 years, based on ionospheric physics and chemistry, mostly controlled by Space Weather conditions. However, it is not understood in depth if the residual or mismodelled component of the ionosphere's behaviour is predictable in principle as a simple dynamical system, or is conversely so chaotic to be practically stochastic. Working on an ionospheric quantity very popular in aeronomy, we here suggest data analysis techniques to deal with the question of how chaotic and how predictable the local ionosphere's behaviour is. In particular, we calculate the correlation dimension D2 and the Kolmogorov entropy rate K2 for two one-year long time series of data of vertical total electron content (vTEC), collected on the top of the mid-latitude GNSS station of Matera (Italy), one for the year of Solar Maximum 2001 and one for the year of Solar Minimum 2008. The quantity D2 is a proxy of the degree of chaos and dynamical complexity. K2 measures the speed of destruction of the time-shifted self-mutual information of the signal, so that K2-1 is a sort of maximum time horizon for predictability. The analysis of the D2 and K2 for the vTEC time series allows to give a measure of chaos and predictability of the Earth's ionosphere, expected to limit any claim of prediction capacity of any model. The results reported here are preliminary, and must be intended only to demonstrate how the application of the analysis of these quantities to the ionospheric variability is feasible, and with a reasonable output.Published3682A. Fisica dell'alta atmosferaJCR Journa
Dynamics of volcanic vortex rings
No full textVortex rings can easily be generated in the laboratory or with homemade devices, but they have also been observed on volcanoes, since the eighteenth century. However, the physical conditions under which volcanic vortex rings form are still unknown. In order to better understand this phenomenon and provide clues on the dynamics of the volcanic vortex rings, we performed a series of finite element simulations to investigate which model configuration leads to the rings formation that best matches the field observations. Results show that the formation of volcanic vortex rings requires a combination of fast gas release from gas bubbles (slugs) at the top of the magma conduit and regularity in the shape of the emitting vent. Our findings offer important insights into the geometry of the uppermost portion of vortex-forming volcanic conduits. Volcanic vortex ring studies may form the basis for a cross-disciplinary assessment of the upper conduit dynamics of volcanic vents.Published2369OSV2: Complessità dei processi vulcanici: approcci multidisciplinari e multiparametriciJCR Journa
Data Fusion for Satellite-Derived Earth Surface: The 2021 Topographic Map of Etna Volcano
No full textWe present a new automatic procedure for updating digital topographic data from multi-source satellite imagery, which consists in the production of Digital Surface Models (DSMs) from high resolution optical satellite images, followed by a context-aware fusion that exploits the complementary characteristics of the multi-source DSMs. The fused DSM minimizes blunders and artifacts due to occlusions (e.g., the presence of clouds, snow or ash plumes) in the source images, resulting in improved accuracy and quality versus those that are not merged. The procedure has been tested to produce the 2021 digital topography of Mt Etna, whose summit area is constantly changing and shows the new peak of 3347 m on the north rim of the South East Crater. We also employ the 2021 DSM to measure the volcanic deposits emplaced in the last five years, finding about 120 million cubic meters, with a yearly average volume of about 24 million cubic meters in agreement with the large eruptive rates registered at Mt Etna since the nineteen seventies. The flexibility and modularity of the presented procedure make it easily exportable to other environmental contexts, allowing for a fast and frequent reconstruction of topographic surfaces even in extreme environments.Published198OSV4: Preparazione alle crisi vulcanicheJCR Journa
AI-ready data in space science and solar physics: problems, mitigation and action plan
No full textIn the domain of space science, numerous ground-based and space-borne data of various phenomena have been accumulating rapidly, making analysis and scientific interpretation challenging. However, recent trends in the application of artificial intelligence (AI) have been shown to be promising in the extraction of information or knowledge discovery from these extensive data sets. Coincidentally, preparing these data for use as inputs to the AI algorithms, referred to as AI-readiness, is one of the outstanding challenges in leveraging AI in space science. Preparation of AI-ready data includes, among other aspects: 1) collection (accessing and downloading) of appropriate data representing the various physical parameters associated with the phenomena under study from different repositories; 2) addressing data formats such as conversion from one format to another, data gaps, quality flags and labeling; 3) standardizing metadata and keywords in accordance with NASA archive requirements or other defined standards; 4) processing of raw data such as data normalization, detrending, and data modeling; and 5) documentation of technical aspects such as processing steps, operational assumptions, uncertainties, and instrument profiles. Making all existing data AI-ready within a decade is impractical and data from future missions and investigations exacerbates this. This reveals the urgency to set the standards and start implementing them now. This article presents our perspective on the AI-readiness of space science data and mitigation strategies including definition of AI-readiness for AI applications; prioritization of data sets, storage, and accessibility; and identifying the responsible entity (agencies, private sector, or funded individuals) to undertake the task.Published1203598OSA3: Climatologia e meteorologia spazialeJCR Journa
Melting of fault gouge at shallow depth during the 2008 MW 7.9 Wenchuan earthquake, China
No full textTypical rocks at shallow depths of seismogenic faults are fluid-rich gouges. During earthquakes, on-fault frictional heating may trigger thermal pressurization and dynamic fault weakening. We show that frictional melting, rather than thermal pressurization, occurred at shallow depths during the 2008 MW 7.9 Wenchuan earthquake, China. One year after the Wenchuan earthquake, we found an ~2-mm-thick, glass-bearing pseudotachylyte (solidified frictional melt) in the fault gouges retrieved at 732.6 m depth from the first borehole of the Wenchuan Earthquake Fault Scientific Drilling Project. The matrix of pseudotachylyte is enriched in barium and cut by barite-bearing veins, which provide evidence of co- and postseismic fluid percolation. Because pseudotachylyte can be rapidly altered in the presence of percolating fluids, its preservation suggests that gouge melting occurred in a recent large earthquake, possibly the Wenchuan earthquake. Rock friction experiments on fluid-rich fault gouges deformed at conditions expected for seismic slip at borehole depths showed the generation of pseudotachylytes. This result, along with the presence of a second slip zone attributed to the Wenchuan earthquake at 589.2 m depth, implies that during large earthquakes, frictional melting can occur at shallow depths and that seismic slip can be accommodated by multiple faults. This conclusion is consistent with the evidence from surface faulting that multiple ruptures propagated during the Wenchuan earthquake.Published345–350OST3 Vicino alla fagliaJCR Journa
Hydrological and volcano-related gravity signals at Mt. Somma–Vesuvius from ∼20 yr of time-lapse gravity monitoring: implications for volcano quiescence
No full textThis article has been accepted for publication in Geophysical Journal International ©:The Author(s) 2023. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.Uploaded in accordance with the publisher's self-archiving policy.
All rights reserved.We report on about 20 yr of relative gravity measurements, acquired on Mt. Somma–Vesuvius volcano in order to investigate the hydrological and volcano-tectonic processes controlling the present-day activity of the volcano. The retrieved long-term field of time gravity change (2003–2022) shows a pattern essentially related to the subsidence, which have affected the central part of the volcano, as detected by the permanent GNSS network and InSAR data. After reducing the observations for the effect of vertical deformation, no significant residuals are found, indicating no significant mass accumulation or loss within the volcanic system. In the north-western sector of the study area, at the border of the volcano edifice, however, significant residual positive gravity changes are detected which are associated to ground-water rebound after years of intense exploitation of the aquifers. On the seasonal timescale, we find that stations within the caldera rim are affected by the seasonal hydrological effects, while the gravity stations at the base of the Vesuvius show a less clear correlation. Furthermore, within the caldera rim a multiyear gravity transient is detected with an increase phase lasting about 4 yr followed by a slower decrease phase. Analysis of rain data seem to exclude a hydrological origin, hence, we hypothesize a deeper source related to the geothermal activity, which can be present even if the volcano is in a quiescent state. We infer the depth and volume of the source by inverting the spatial pattern of the gravity field at the peak of the transient. A volume of fluids of 9.5 × 107 m3 with density of 1000 kg m−3 at 2.3 km depth is capable to fit reasonably well the observations. To explain the gravity transient, simple synthetic models are produced, that simulate the ascent of fluids from a deep reservoir up to the depth of 2.3 km and a successive diffusion within the carbonate aquifer hosting the geothermal system. The whole process appears to not significantly affect the seismicity rate and the deformation of the volcano. This study demonstrates the importance of a 4-D gravity monitoring of a volcano to understand its complex gravity signals that cover different spatial and temporal scales. Discriminating the different contributions that mix up in the observed gravity changes, in particular those due to hydrologic/anthropogenic activities form those due to the geothermal dynamics, is fundamental for a complete and reliable evaluation of the volcano state.Published1565–1580OSV2: Complessità dei processi vulcanici: approcci multidisciplinari e multiparametriciJCR Journa
NESTOREv1.0: A MATLAB Package for Strong Forthcoming Earthquake Forecasting
No full textThis article presents the first publicly available version of the NExt STrOng Related
Earthquake (NESTORE) software (NESTOREv1.0) designed for the statistical analysis of
earthquake clusters. NESTOREv1.0 is a MATLAB (www.mathworks.com/products/
matlab , last accessed August 2022) package capable of forecasting strong aftershocks
starting from the first hours after the mainshocks. It is based on the NESTORE algorithm,
which has already been successfully applied retrospectively to Italian and California seismicity.
The code evaluates a set of features and uses a supervised machine learning
approach to provide probability estimates for a subsequent large earthquake during a
seismic sequence. By analyzing an earthquake catalog, the software identifies clusters
and trains the algorithm on them. It then uses the training results to obtain forecasting
for a test set of independent data to estimate training performance. After appropriate
testing, the software can be used as an Operational Earthquake Forecasting (OEF)
method for the next stronger earthquake. For ongoing clusters, it provides near-real-time
forecasting of a strong aftershock through a traffic light classification aimed at assessing
the level of concern. This article provides information about the NESTOREv1.0 algorithm
and a guide to the software, detailing its structure and main functions and showing the
application to recent seismic sequences in California. By making the NESTOREv1.0 software
available, we hope to extend the impact of the NESTORE algorithm and further
advance research on forecasting the strongest earthquakes during seismicity clusters.Published2003–2013OST4 Descrizione in tempo reale del terremoto, del maremoto, loro predicibilità e impattoOST5 Verso un nuovo MonitoraggioJCR Journa
The 2021–2022 Genoa seismic sequences reveal distributed strike-slip deformation in the Alps-Apennines transition zone, NW Italy
No full textThe complex tectonic evolution of the Alps-Apennines transition zone in NW Italy is still a matter of debate. In
this work, we analyze the 2021–2022 seismic sequences around Genoa to understand how convergence between
Africa and Europe is presently accommodated across the Alps-Apennines transition zone. The map-view distribution
of HypoDD-relocated seismic events reveals a NE-SW alignment for the Savignone seismic sequence, and
NNW-SSE alignments for the Borzonasca and Bargagli sequences. The Borzonasca seismic sequence plots in
correspondence of the Villalvernia-Varzi-Ottone Fault, which is often considered as the boundary between the
Alps and the Apennines, whereas no seismicity is documented along the Sestri-Voltaggio Fault. The main-shock
focal solutions are invariably strike-slip, with near-vertical NNW-SSE and NE-SW to ENE-WSW nodal planes. The
evident earthquake alignments in the study area mark active, km-scale fault planes in the upper crust, pointing to
a scenario of distributed strike-slip deformation in the transition zone between the Alps and the Apennines. The
NE-SW faults are inherited structures that underwent major Neogene rotations and are no longer suitably oriented
to accommodate the northward motion of Adria relative to Europe. The Bargagli seismic sequence may
reflect the formation of new NNW-SSE strike-slip faults in the upper crust that are more suitably oriented to
accommodate the present-day stress field, consistent with the seismotectonic framework outlined by recent
works in the nearby regions of the Adria-Europe plate-boundary zone. Our results highlight the important role of
strike-slip faulting in the Adria-Europe plate boundary zone not only in the past, but also during its present-day
evolution.Published230101OST3 Vicino alla fagliaJCR Journa
Lava flow hazard modeling during the 2021 Fagradalsfjall eruption, Iceland: applications of MrLavaLoba
No full textThe 6-month-long effusive eruption at the Fagradalsfjall volcano in 2021 is the most visited eruption site in Iceland to date (June 2023), and it needed intense lava flow hazard assessment. In this study we document how strategies for lava flow modeling were implemented using the stochastic model MrLavaLoba to evaluate hazards during this effusive event. Overall, the purposes were threefold: (a) pre-eruption simulations to investigate potential lava inundation of critical infrastructure, (b) syn-eruption simulations for short-term (2-week time frame) lava flow hazard assessment and (c) syn-eruption simulations for long-term (months to years) hazard assessments. Additionally, strategies for lava barrier testing were developed, and syn-eruption topographic models were incorporated into simulations in near real time. The model provided promising results that were shared regularly at stakeholder meetings with the monitoring personnel, scientists and civil-protection representatives helping to identify potential short-term and long-term lava hazards. This included evaluation of the timing of barrier overflow and the filling and spilling of lava from one valley to another.
During the crisis the MrLavaLoba model was updated to increase functionality such as by considering multiple active vents. Following the eruption, the model was optimized substantially, decreasing the computational time required for the simulations and speeding up the delivery of final products.Published3147–3168OSV2: Complessità dei processi vulcanici: approcci multidisciplinari e multiparametriciJCR Journa