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Weak upper-mantle base revealed by postseismic deformation of a deep earthquake
No full textMantle viscosity plays a key role in the Earth's internal dynamics and thermal history. Geophysical inferences of the viscosity structure, however, have shown large variability depending on the types of observables used or the assumptions imposed [1-3]. Here, we study the mantle viscosity structure by using the postseismic deformation following a deep (approximately 560 km) earthquake located near the bottom of the upper mantle. We apply independent component analysis [4] to geodetic time series to successfully detect and extract the postseismic deformation induced by the moment magnitude 8.2, 2018 Fiji earthquake. To search for the viscosity structure that can explain the detected signal, we perform forward viscoelastic relaxation modelling [5,6] with a range of viscosity structures. We find that our observation requires a relatively thin (approximately 100 km), low-viscosity (10^17 to 10^18 Pa s) layer at the bottom of the mantle transition zone. Such a weak zone could explain the slab flattening [7] and orphaning [8] observed in numerous subduction zones, which are otherwise challenging to explain in the whole mantle convection regime. The low-viscosity layer may result from superplasticity [9] induced by the postspinel transition, weak CaSiO3 perovskite [10], high water content [11] or dehydration melting [12].Published455–460OST2 Deformazione e Hazard sismico e da maremotoJCR Journa
Constraints on the lunar core viscosity from tidal deformation
No full textWe use the tidal deformations of the Moon induced by the Earth and the Sun as a tool for studying the inner structure of our satellite.
Based on measurements of the degree-two tidal Love numbers and and dissipation coefficients from the GRAIL mission, Lunar
Laser Ranging and Laser Altimetry on board of the LRO spacecraft, we perform Monte Carlo samplings for 120,000 possible combinations of
thicknesses and viscosities for two classes of the lunar models. The first one includes a uniform core, a low viscosity zone (LVZ) at
the core-mantle boundary, a mantle and a crust. The second one has an additional inner core. All models are consistent with the lunar t
otal mass as well as its moment of inertia. By comparing predicted and observed parameters for the tidal deformations we find that the
existence of an inner core cannot be ruled out. Furthermore, by deducing temperature profiles for the LVZ and an Earth-like mantle, we
obtain stringent constraints on the radius (500 1) km, viscosity, Pas and the density (3400
10) kg/m of the LVZ. We also infer the first estimation for the outer core viscosity, (2.07 ± 1.03) × 10 Pa·s, for tw
o different possible structures: a Moon with a 70 km thick outer core and large inner core (290 km radius with a density of 6000 kg/m), and a Moon with a thicker outer core (169 km thick) but a denser and smaller inner core (219 km radius for 8000 kg/m).Published1154265IT. Osservazioni satellitariJCR Journa
Aeolus winds impact on volcanic ash early warning systems for aviation
No full textForecasting volcanic ash atmospheric pathways is of utmost importance for aviation. Volcanic ash can interfere with aircraft navigational instruments and can damage engine parts. Early warning systems, activated after volcanic eruptions can alleviate the impacts on aviation by providing forecasts of the volcanic ash plume dispersion. The quality of these short-term forecasts is subject to the accuracy of the meteorological wind fields used for the initialization of regional models. Here, we use wind profiling data from the first high spectral resolution lidar in space, Aeolus, to examine the impact of measured wind fields on regional NWP and subsequent volcanic ash dispersion forecasts, focusing on the case of Etna's eruption on March 2021. The results from this case study demonstrate a significant improvement of the volcanic ash simulation when using Aeolus-assimilated meteorological fields, with differences in wind speed reaching up to 8 m/s when compared to the control run. When comparing the volcanic ash forecast profiles with downwind surface-based aerosol lidar observations, the modeled field is consistent with the measurements only when Aeolus winds are assimilated. This result clearly demonstrates the potential of Aeolus and highlights the necessity of future wind profiling satellite missions for improving volcanic ash forecasting and hence aviation safety.Published7531OSV2: Complessità dei processi vulcanici: approcci multidisciplinari e multiparametriciJCR Journa
Aseismic Creep, Coseismic Slip, and Postseismic Relaxation on Faults in Volcanic Areas: The Case of Ischia Island
No full textWe performed a joined multitemporal and multiscale analysis of ground vertical movements around the main seismogenic source of Ischia island (Southern Italy) that, during historical and recent time, generated the most catastrophic earthquakes on the island, in its northern sector (Casamicciola fault). In particular, we considered InSAR (2015–2019) and ground-levelling data (1987–2010), attempting to better define the source that caused the recent 2017 earthquake and interpret its occurrence in the framework of a long-term behavior of the fault responsible for the major historical earthquakes in Casamicciola. Our results unambiguously constrain the location and the kinematics of the 2017 rupture and further confirm the presence of a relatively large sliding area west of the 2017 surface break. Overall, the studied seismogenic fault reveals a complex dynamic, moving differentially and aseismically in the pre- and post-seismic event, in response to the long-term subsidence of the central sector of the island, dominated by Mt. Epomeo. The fault segment that slipped coseismically also is evidence of post-seismic viscous relaxation. The long-term differential vertical movement on the apparently creeping eastern sector of the Casamicciola fault provides an estimate of the slip rate occurring on the fault (0.82 mm/y−1). The analysis of the time of occurrence and the magnitude of the known historical earthquakes reveals that this rate is consistent with the recurrence of the earthquakes that occurred during at least the past three centuries and suggests that the time to the next seismic event at Casamicciola might be a few decades. More generally, our findings provide evidence of the link between subsidence and earthquakes in volcanic areas indicating, in this case, a high hazard for the island of Ischia. Results might be also useful for characterizing capable faulting in similar volcano-tectonic settings worldwide.Published17913T. Fisica dei terremoti e Sorgente SismicaJCR Journa
The Taverna San Felice Dike (NE of Roccamonfina Volcano): Unraveling Magmatic Intrusion Processes and Volcano‐Tectonics in the Tyrrhenian Margin of the Southern Apennines
No full textThe Roccamonfina volcano is located within the Garigliano Graben (southern Apennines, Italy) and has been active throughout the Middle-Late Pleistocene. Along its polyphase volcanic history (630–55 ka), including several caldera-forming eruptions (385–230 ka), several effusive/mildly explosive monogenetic events occurred along the volcano slopes, within the summit caldera, and along the graben-bounding carbonate reliefs. In this paper, we present a multidisciplinary study of a mafic magmatic feeder dike intruded within the Meso-Tertiary carbonates and overlying Lower Pleistocene breccias of Mt Cesima, northeast of the Roccamonfina volcano. We performed a stratigraphic and structural survey of the area and petrographic analyses on several samples of the dike. Results indicate that a ∼1 km long fissure fed an eruption that also emplaced a Strombolian pyroclastic sequence. Petrological data show that an open-system mafic recharge fueled the tephritic magma that fed the eruption, whereas no evidence of significant pre/syn-eruptive assimilation of carbonate has been identified. Stratigraphic and petrological data do not allow to firmly constrain the timing of the eruption, which could belong both to the pre-Brown Leucitic Tuff (>354 ka) and to the post-White Trachytic Tuffs (<230 ka) epochs of activity of the Roccamonfina volcano. Structural data show that the dike is broadly oriented E-W and changes direction toward NE-SW in correspondence with a pre-existing fault damage zone. We suggest that magma was intruded during an N-S trending extensional event in the Middle Pleistocene, whose prolonged activity resulted in regional uplift and exhumation of regional significance.Publishede2023GC010994OSV2: Complessità dei processi vulcanici: approcci multidisciplinari e multiparametriciJCR Journa
The Use of Satellite Synthetic Aperture Radar Imagery to Assist in the Monitoring of the Time Evolution of Challenging Coastal Environments: A Case Study of the Basilicata Coast
No full textThis study focuses on a very complex environment, namely the Ionian coast of the Basilicata region, Southern Italy, which includes different kinds of beaches, river mouths and built-up areas. This complex environment is used as a test case to analyze the time variability of the coastline using measurements that were remotely sensed by the satellite European Copernicus Synthetic Aperture Radar (SAR) mission. First, the accuracy of the coastline, extracted by the SAR, is discussed with respect to finer-spatial-resolution drone-based light detection and ranging (LIDAR) measurements. Then, a time series of SAR dual-polarimetric measurements acquired by the European Copernicus mission is used to discuss the time variability of the coastline of the area of interest in a time period spanning from 2015 to 2021. The experimental results show that the accuracy of the SAR-based coastline is better than 15 m, which is reasonably good precision for monitoring the erosion/accretion processes that characterize the area of interest at a moderate scale. The estimated time variability of the extracted coastline suggests a dominant erosion process, which is always within 60 m.Published212OSA4: Ambiente marino, fascia costiera ed Oceanografia operativaJCR Journa
Geophysical Constraints to Reconstructing the Geometry of a Shallow Groundwater Body in Caronia (Sicily)
No full textThe characterization of a groundwater body involves the construction of a conceptual
model that constitutes the base knowledge for monitoring programs, hydrogeological risk assessment,
and correct management of water resources. In particular, a detailed geological and geophysical
approach was applied to define the alluvial Caronia Groundwater Body (CGWB) and to reconstruct
a hydrogeological flow model. The analysis of the CGWB, located in north-eastern Sicily, was
initially approached through a reanalysis of previous stratigraphic (boreholes) and geophysical
(vertical electrical soundings and seismic refraction profiles) data, subsequently integrated by new
seismic acquisitions, such as Multichannel Analysis of Surface Waves (MASW) and horizontalto-
vertical seismic ratio (HVSR). The analysis and reinterpretation of geoelectrical data allowed
the construction of a preliminary 3D resistivity model. This initial modeling was subsequently
integrated by a geophysical data campaign in order to define the depth of the bottom of the shallow
CGWB and the thickness of alluvial deposits. Finally, a preliminary mathematical model flow
was generated in order to reconstruct the dynamics of underground water. The results show that
integration of multidisciplinary data represent an indispensable tool for the characterization of
complex physical systems.Published3206JCR Journa
Risultati del sondaggio sulle politiche di gestione istituzionale dei dati scientifici
No full textIl presente rapporto prosegue le attività del Gruppo di lavoro (GdL) Open Science, istituito nel 2021 dalla Consulta dei Presidenti (CoPER) degli Enti Pubblici di Ricerca (EPR) per favorire la promozione delle istanze dell'Open Science tra gli EPR, con le Università rappresentate dalla CRUI e anche con i diversi soggetti che, a vario titolo, partecipano alle tematiche della Scienza Aperta.
Il suddetto GdL è suddiviso in Gruppi Tematici che, su base volontaria, provvedono alla preparazione di documenti e azioni per la promozione e il sostegno delle politiche di scienza aperta in Italia, così come pianificato nel documento programmatico, in collaborazione con altri attori operanti sulla scena nazionale.
Dopo la pubblicazione dei risultati relativi al sondaggio sulle Politiche e le infrastrutture per l'Open Access per pubblicazioni e letteratura grigia, questo secondo sondaggio fotografa, alla primavera del 2023, il grado di adozione di politiche e pratiche relative alla gestione istituzionale dei dati scientifici secondo il paradigma della Scienza Aperta. Questo nuovo sondaggio nasce a valle delle discussioni sui Dati Aperti condotte in occasione del primo convegno GdL Open Science a dicembre 2022 i cui punti salienti sono raccolti nella presentazione dal titolo “Esperienze di gestione degli Open Data negli Enti pubblici di Ricerca”.
La struttura del sondaggio è un adattamento e una semplificazione del modello sistematico proposto dall’ European Open Science Cloud (EOSC) Steering Board al fine di monitorare i contributi nazionali a EOSC, scelto anche in accordo con i suggerimenti del Tavolo di Lavoro per l’implementazione del Programma Nazionale per la Scienza Aperta (PNSA) del Ministero dell’Università e della Ricerca (MUR).
Sulla base dei risultati emersi da questo sondaggio, il Gruppo Tematico Open Data del GdL Open Science della CoPER intende avviare un monitoraggio permanente allo scopo di rendere disponibile uno strumento utile a coordinare gli sforzi degli EPR nella propria gestione istituzionale dei dati.
Il presente documento fornisce una panoramica della struttura del sondaggio e dei risultati ottenuti. Al sondaggio hanno risposto 14 EPR tra quelli partecipanti al GdL Open Science della CoPER, tramite i rispettivi rappresentanti.Istituto Nazionale di Geofisica e Vulcanologia (INGV), Istituto Nazionale di Oceanografia e Geofisica Sperimentale (OGS), Agenzia Nazionale per le nuove tecnologie, l’energia e lo sviluppo economico sostenibile (ENEA), Consiglio per la ricerca in agricoltura e l'analisi dell'economia agraria (CREA), Istituto Superiore per la Protezione e la Ricerca Ambientale (ISPRA), Istituto Nazionale di Fisica Nucleare (INFN)PublishedOST5 Verso un nuovo Monitoraggi
A SO2 flux study of the Etna volcano 2020–2021 paroxysmal sequences
No full textThe persistent open-vent degassing of Mt. Etna is often punctuated by monthslong
paroxysmal sequences characterized by episodes of violent Strombolian to
lava fountaining activity. Understanding these gas-fueled transitions from
quiescence to eruption requires routine measurement of gas fluxes. Here, we
report SO2 flux measurements, obtained from a permanent UV camera system,
collected over a two-year-long period spanning two paroxysmal sequences of
Etna’s New South East Crater (NSEC) in December 2020/April 2021 and May/
October 2021. In both cases, SO2 flux increased from ≤ 3250 Mg/day during
“ordinary” activity to ≥ 4200 Mg/day. We interpret these distinct SO2 degassing
regimes in light of seismic and thermal observations and drawing on numerical
simulations of sulfur degassing constrained by parental melt sulfur contents in
Etna’s hawaiites. We find that initiation of a paroxysmal sequence results from
an approximate doubling of the time-averaged rate of magma supply (and
degassing) above the sulfur exsolution level (~150 MPa pressure), to >4m3/s.
This corroborates recent models that argue for the triggering of paroxysmal
sequences by escalating supply of volatile-rich magma to a reservoir ~3–4 km
below the summit region. The non-stationary nature of magma flow and volcanic
degassing we identify highlights the need for sustained surveillance to
characterize long-term atmospheric budgets of volcanic volatilesPublished1115111OSV2: Complessità dei processi vulcanici: approcci multidisciplinari e multiparametriciJCR Journa
Spatial variability of non-ergodic GMM residuals related to source and path effects in Italy
No full textIn this study, we exploit the advantages of non-ergodic modelling of the ground motion to map the regional characteristics of source and propagation effects in Italy. In particular, we focused on the study of source and propagation effects obtained from the decomposition of the total residuals, i.e. the logarithmic difference of ITACAext observations and the model predictions, for active crustal earthquakes in Italy. The spatial trends, obtained from interpolating the residuals, clearly showed areas where the motion was significantly different from that predicted by the reference model, and in particular was underestimated. This is the case, for example, for many events with epicentres in northern Italy and the southern Ionian Sea. In addition, the study shows that paths across the Po Valley and the Adriatic coast are characterised by slower attenuation compared to that observed in the central Apennines. In addition, a marked difference between attenuation in the volcanic domain of Etna and the Hyblaean Mountains is clearly observed.Published417-432OST2 Deformazione e Hazard sismico e da maremotoJCR Journa