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The February–April 2021 sequence of lava fountain paroxysms on Mt Etna: source mechanism deciphered from ground-based and satellite survey of volcanic gas emissions
No full textBetween 16 February and 1 April 2021, the Southeast Crater (SEC) of Mt Etna produced a spectacular sequence of 17 lava fountain paroxysms, separated by 2.5 days on average, which generated ≥ 10 km high eruptive columns and heavy tephra
fallout over populated surroundings. We examine the magmatic processes responsible for these events based on pre- and syn-eruptive data for the mass flux and chemistry of Etna gas emissions, surveyed both from the ground (scanning DOAS,
OP-FTIR spectroscopy) and from space (TROPOMI, SEVIRI), and comparing with the seismic tremor. Bulk plume SO2 emission rates determined from the ground and from space are consistent with one another. We show that after several months
of background summit activity, sustained since June 2020 by open-system degassing of ~ 29 × 106 m3 (DRE) of magma through the central volcano conduits, an influx of deeply derived primitive magma led to a pressure build-up phase from
early December 2020 to 13 February 2021, marked by a rapid increase in the SO2 flux and tremor (the former interpreted to represent an ~ 3 times higher magma degassing rate) and decreasing SO2/HCl plume ratio. A series of 17 lava fountains began immediately after a shallow seismic cluster and a sharp drop in the SO2 emission rate from the summit craters, reflecting the lateral transfer of pressurized primitive magma to beneath the SEC. The fountain paroxysms were characterized by sharp increases in tremor amplitude, intense SO2 release, and higher volcanic gas SO2/HCl ratios. The magnitude of SO2 emission rate correlates with the proportion of primitive magma in co-erupted products during the first half of the sequence. The estimated total gas discharge, compared to the co-erupted tephra mass, suggests a large excess gas release for most events, which is proportional to the length of the repose interval. Combining these observations with models of S and Cl degassing from Etna trachybasalt, we infer that the February–April 2021 lava fountain series resulted from the recurrent accumulation of H2O- CO2-rich bubble foams at ~ 2–3 km depth beneath SEC, whose periodic collapse promoted fast magma ascent and fragmentation associated with essentially syn-eruptive degassing of S and Cl. Our study thus provides further insight into the complexity of magmatic processes determining lava fountain paroxysms at Mt Etna and, possibly, other basaltic volcanoes.PublishedJCR Journa
Effetti diretti e indiretti del terremoto senese del 1467: una rilettura innovativa tra dati storici e archeosismologici inediti.
No full textIntroduzione Lo studio archeosismologico di centri storici situati in aree sismiche permette di analizzare gli effetti di specifici terremoti sulle componenti materiali e di raccogliere dati utili per apprezzare le dinamiche sociali, economiche e politiche scaturite da tali eventi. 1 Il progetto PROTECT finanziato * Il progetto PROTECT-Knowledge for PReventiOn. Technique for reparing seismic damage from medieval period to modern era è stato finanziato dal programma "Horizon 2020 research and innovation" dell'Unione Europea con una Marie Skłodowska-Curie Individual Fellowship (grant agreement No. 101018762) presso l'École Normale Supérieure di Parigi, il cui responsabile scientifico è il dott. Andrea Arrighetti. Il presente contributo costituisce una parte del lavoro svoltoPublishedN/A or not JC
A dataset of hydrological effects induced by historical and modern earthquakes in Southern Apennines (Italy)
No full textWe present a dataset documenting hydrological changes associated with seismic events of magnitude ranging from M = 4.1 and M = 7.1, occurring in Southern Italy between 1688 and 2019. Our study focused on three key areas of Southern apennines, namely (from NW to SE) the Sannio-Matese, the Irpinia-Mefite, and Pollino regions. The dataset includes observations of stream, spring, and well discharge variations; liquefaction; turbid flow; changes in the chemical-physical parameters of water. the data were compiled from various sources spanning ∼330 years, including genre literature, historical chronicles, seismic postcards, and modern scientific papers. The resulting database comprises 610 records of hydrological effects induced by 40 seismic events, each record containing 12 numerical and textual fields of relevant information.PublishedJCR Journa
Effects of X2.8-class solar flare on the ionosphere occurred during the recovery phase of a geomagnetic storm over South American and Antarctic sectors
No full textIn this investigation, we present and discuss the effects of an X2.8-class solar flare occurred on 14 December 2023 on the ionospheric F region and on the geomagnetic field over South American and Antarctic sectors. This flare coincides with the recovery phase of a geomagnetic storm. To this end, we rely on vertical total electron content (VTEC) observations from nearly 250 Global Positioning System (GPS) receiver stations over South American and Antarctic sectors, complemented by in-situ electron density observations from Swarm satellites, magnetometer measurements, and ionospheric sounding observations from ionosondes. The magnetic observations show a large increase in the variations of the horizontal component (DH) of the geomagnetic field and equatorial electrojet (EEJ) currents at all stations, synchronized with the increase in X-rays flux, indicating solar flare effects or magnetic crochet on the Earth's geomagnetic field. VTEC shows how the impact of the solar flare on the ionosphere is enhanced from east to west of South America in the equatorial and low-latitudes. VTEC from a specific GPS satellite-receiver also shows great effects at mid-latitudes. Results are confirmed and further elaborated through Swarm in-situ observations. In addition, an asymmetry is observed in the equatorial ionization anomaly (EIA), in which the eastern South American sector shows an intensified EIA compared to the western sector. Ionospheric sounding observations by ionosondes show total fade out in the echo traces of the ionograms, characterizing blackouts in the radio signals from equatorial to low-latitudes. Overall, our results show that an X-class solar flare occurring near the limb of the solar disk is capable of producing effects on the Earth's ionosphere with similar or even stronger intensities than flares occurring at the center of the solar disk.PublishedOSA3: Climatologia e meteorologia spazialeJCR Journa
The Garisenda Tower in 1904: displacement time series
No full textNel 1904, il professor Francesco Cavani, su incarico del Comune di Bologna, fu chiamato a valutare la stabilità della Torre Garisenda. A tal fine, sviluppò un innovativo sistema di monitoraggio, basato su un filo a piombo fissato a circa 40 metri di altezza sulla parete Sud e su cannocchiali specializzati, dotati di un doppio sistema di lenti e fuochi, in grado di rilevare spostamenti con una precisione fino a un ventesimo di millimetro. Le tavole allegate alla sua relazione presentano in dettaglio i dati di monitoraggio, comprensivi delle serie temporali degli spostamenti verso Est e Nord, rappresentate in scala ingrandita 20:1.
In questo studio, le serie originali sono state digitalizzate, scalate ed esportate per essere analizzate con metodi moderni. L’obiettivo è quello di estrarre informazioni sulle caratteristiche dinamiche del movimento della torre, sia nel dominio del tempo che in quello delle frequenze. I risultati ottenuti mettono in evidenza le oscillazioni e le relative ampiezze, offrendo una lettura moderna e aggiornata del comportamento dinamico della struttura a oltre un secolo di distanza. Questo lavoro si propone come strumento per divulgare alcune informazioni di base sul comportamento della torre nel passato, al fine di valutare, in studi futuri, eventuali cambiamenti significativi nella caratterizzazione cinematica dei suoi movimenti. Inoltre si annunciano futuri sviluppi per aumentare la comprensione dei limiti spaziali e temporali dei risultati in considerazione delle imperfezioni dei grafici storici.PublishedJCR Journa
High precision deformation monitoring of landslide via corner reflector-, persistent scatterer-, and distributed scatterer-synthetic aperture radar interferometry three-scale robust combination
No full textSynthetic aperture radar interferometry (InSAR) has been successful in detecting and monitoring landslides over the last decade. However, its accuracy encounters challenges such as spatial and temporal decorrelation, unwrapping errors, and atmospheric delays. These issues are particularly pronounced in steep, intricate, and densely vegetated mountainous areas prone to landslides, which will complicate the processing of InSAR data and impact the reliability of landslide detection and monitoring. We introduce a approach that combines corner reflectors (CRs), persistent scatterers (PSs), and distributed scatterers (DSs) using a three-scale robust fusion method. The goal of this method is to utilize CR as consistent reference points, PSs as constraint factors, and DSs as variables to be estimated for improving the precision and dependability of deformation inversion. Moreover, maximum likelihood estimation is utilized to mitigate the influence of gross errors, enhancing the robustness of results derived from InSAR data processing. The three-scale robust fusion method demonstrated superior performance to the DS-InSAR method using both advanced synthetic aperture radar (ASAR) and phased array type L-band synthetic aperture radar (PALSAR) datasets, as evidenced by increased measurement points and enhanced monitoring accuracy compared with global positioning system (GPS) measurements. This robust fusion method is particularly suited for known landslides outfitted with CRs, which have garnered substantial research interest and have established various ground-based deformation monitoring systems including leveling, global navigation satellite system (GNSS), and CRs. In scenarios where CRs are absent, alternative methods such as GNSS or leveling can be deployed to function as reference points, effectively serving a constraining role. Moreover, for concealed and unidentified landslides that lack pre-installed monitoring infrastructure, the robust fusion method remains applicable to integrate PSs and DSs and facilitates the selection of several highly coherent and stable ground objects to act as reference points, thereby achieving similar outcomes to those in sites with established CRs. The proposed method is appropriate for most landslide disaster monitoring scenarios in complex mountainous regions.PublishedJCR Journa
Assessment of Slow Deformations and Landslide Modelling in the Urban Area through a Multi-Methodological Approach
No full textSlow-moving landslides are widespread in the Mediterranean area, causing damage to the exposed facilities and economic losses in many countries. The recognition of slow-moving landslides in urban areas is always a difficult task to deal with because the presence of buildings, infrastructures, and human activities usually conceals the morphological signs of these landslide activities. So, in the last decades, numerous researchers have shown new methodologies to deepen the studies of similar instability phenomena. The present research is based on an integrated approach to investigate the landslide boundaries, type of movement, failure surface depth, and vulnerability state of buildings in Rota Greca Village (Calabria region, southern Italy) affected by a slowmoving landslide. For this purpose, multi-source data were acquired through geological and geomorphological surveys, recognition of landslide-induced damage on the built environment, subsurface investigations (e.g., continuous drill boreholes, Standard Penetration Test, Rock Quality Designation index and inclinometer monitoring), laboratory tests (direct shear tests on undisturbed samples), geophysical survey, and InSAR-derived map of deformation rates. The complete integration of multi-source data allowed for the construction of reliable landslide modelling with relative geotechnical properties. In addition, the cross-comparison between surface deformation data by SAR images and severity damage level collected on the exposed buildings enabled to obtain the vulnerability map of the built area. In particular, the achieved goals highlighted two failure surfaces at about-13 and-25 m depth, causing a high vulnerability value for the buildings allocated in the central portion of the Rota Greca Village. The knowledge acquired by the multi-approach can be used to manage and implement appropriate landslide risk mitigation strategies, providing helpful advice and best practices to state-run organisations and stakeholders for landslide management in urban sites.PublishedJCR Journa
Earthquake frequency-magnitude distribution at Mount Etna sheds light on magma ascent in the volcano’s plumbing system
No full textActive volcanoes in densely populated areas are generally monitored through geological observations, geophysical, and geochemical data, which provide information on magma movement in the uppermost crust, allowing only short-term predictions of volcanic activity. However, deep magma recharge processes remain poorly understood. Here, we show that temporal variations in the slope of earthquake frequency-magnitude distribution (b value) at Mount Etna, a proxy for crustal stress changes, can track magma movements from deep to shallow crustal levels. Analyzing two decades of seismicity (2005–2024) across three crustal sectors, we distinguished magma recharge from the mantle, its transfer and storage at intermediate depths, and final ascent to the surface. Moreover, we found that b value time variations can precede geochemical anomalies from magma ascent and its eruption by a few months. Our results suggest that b value monitoring could have anticipated volcanic crises, supporting its integration into multiparametric surveillance systems for medium and long-term volcano monitoring.PublishedJCR Journa
Multiple mush generations provide insight into the longevity of openconduit basaltic volcanoes
No full textInvestigating the dynamics and timescales of magmatic processes in open-conduit basaltic volcanoes is crucial for improving our understanding of explosive eruptions and better assessing volcanic hazards. Among these processes, the role of mush disaggregation and remobilisation within the plumbing system remains rather underexplored. This study examines the longevity and dynamics of the mush system beneath Stromboli volcano (Aeolian Islands, Southern Italy), whose persistent activity results from variable degrees of interaction between different magmatic components. The complex zoning patterns of plagioclase phenocrysts from 2003 to 2021 eruptions have been interrogated by combining in-situ Sr isotope compositions, thermometric modelling, and Mg diffusion chronometry. Our findings shed new light on the physicochemical changes within the plumbing system, the timescales of crystal residence in the shallow reservoir, and the timing of magma recharge events. Timescales of mafic recharges and mush remobilisations recorded by plagioclase suggest rapid magma-mush dynamics during violent explosions but more sluggish during normal activity. Sr isotope heterogeneities in plagioclase reveal that multiple mush generations at Stromboli have been active over millennia, with remobilisation events and crystal recycling driven by mafic magma recharges from depth. This is further supported by a complementary in-situ investigation of clinopyroxene phenocryst cores. A previously unseen, prehistoric, highly radiogenic mush has been actively remobilised in recent years, pointing out that older components of open-conduit basaltic systems may persist longer than previously hypothesised.PublishedJCR Journa
Conceptual model explaining water interactions in the shallow crust: toward developing a reliable simulation model
No full textRobust understanding of the behavior of waters in the upper crust is important scientific challenge to clarify on detailed scale. However, it has not been fully achieved due to the limitation in acquiring the reliable data from great depths in the crust. Particularly, identification of the boundary between upper circulating hydrological systems and sealed crustal fluids underneath, including how deeper hydrothermal parent fluids contribute to shallower crustal systems remain unclear. To address these issues, this study focused on deep drilled boreholes (~1,300 m depth) and collected hot spring water samples (27.1 • C-64.0 • C) from 49 wells in the Kumamoto region, southern Japan. The samples were analyzed for their major dissolved ion concentrations, trace elements (Li and B) and multiple stable isotope ratios such as δ 2 H, δ 13 C, δ 15 N, δ 18 O and δ 34 S. Then these results were compared with those of shallow hydrological systems (~250 m depth) to lead interpretation with combination of other key geophysical, geological and hydrological aspects. Our results revealed that the deep-heated waters, the host reservoirs of hot spring waters, are mainly composed of meteoric waters with minor contributions from hydrothermal fluids of deeper origin, which can account for up to 30 % in some locations. On the other hand, the geochemical characteristics are primarily explained by the components directly sourced from deeper hydrothermal fluids generated in the middle to upper crust and saltwater intrusions near the coast. Analyses of Li and B tracers and water temperature profiles from drilled boreholes suggest that the contribution of deep-heated waters to upper active hydrological systems is negligible, except some local anomalies, and their boundary does not extend depth greater than ca. 350 m. Our study successfully clarifies how waters interact with deep parent hydrothermal fluids, deeply sealed heated waters, active groundwater flow systems and precipitation from various meteoric sources in the shallow crust. This approach is crucial not only for gaining a comprehensive understanding of the nature of waters in the upper crust but also for developing reliable watershed models and for the conservation of groundwater and hot spring resources.PublishedJCR Journa