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When the lava meets the sea: emplacement of the 2–4 ka San Bartolo lava flow field, Stromboli volcano (Italy)
No full textWhen a lava flow enters a body of water, either a lake, sea, river or ocean, explosive interaction may arise. However, when it is
an 'a'ā lava flow entering water, a more complex interaction occurs, that is very poorly described and documented in literature.
In this paper, we analysed the 2–4 ka San Bartolo lava flow field emplaced on the north flank of Stromboli volcano, Italy.
The lava flow field extends from ~ 650 m a.s.l. where the eruptive fissure is located, with two lava channels being apparent
on the steep down to the coast. Along the coast the lava flow field expands to form a lava delta ~ 1 km wide characterised
by 16 lava ‘Flow’ units. We performed a field survey to characterise the features of lava entering the sea and the associated
formation of different components and magnetic measurements to infer the flow fabrics and emplacement process of the lava
flow system. We measured the density, porosity and connectivity of several specimens to analyse the effect of lava-water
interaction on the content in vesicles and their connectivity and conducted a macroscopic componentry analysis (clast count)
at selected sites to infer the character of the eroded offshore segment of the lava flow field and its component flow units. The
collected data allowed us to define the main components of a lava delta fed by 'a'ā lava flows, with its channels, littoral units,
ramps, lava tubes, and inflated pāhoehoe flows controlled by the arterial 'a'ā flow fronts. The spatial organisation of these
components allowed us to build a three-step descriptive model for 'a'ā entering a water. The initial stage corresponds to the
entry of channel-fed 'a'ā lava flow into the sea which fragments to form metric blocks of 'a'ā lava. Continued lava supply to
the foreshore causes flow units to stall while spreading over this substrate. Subsequent 'a'ā lava flow units ramp up behind
the stalled flow front barrier. Lava tubes extending through the stalled flow barrier feed the seaward extension of a bench
made of several pāhoehoe flow units.Open access funding provided by Università degli Studi di
Torino within the CRUI-CARE Agreement. This project is a part of
RS PhD project. This research was funded by MIUR ex-60% attributed
to EZ and PhD grants-Budget 10% attributed to RS. Also, it was
partially funded by the Project FIRST (ForecastIng eRuptive activity
at Stromboli volcano: Timing, eruptive style, size, intensity, and duration),
INGV-Progetto Strategico Dipartimento Vulcani 2019 (Delibera
n. 144/2020). This is contribution no. 637 of the ClerVolc program of
the International Research Center for Disaster Sciences and Sustainable
Development of the University of Clermont Auvergne.Published50OSV1: Verso la previsione dei fenomeni vulcanici pericolosiJCR Journa
A rapid analysis of aftershock processes after a moderate magnitude earthquake with ML methods
No full textSUMMARY
Moderate magnitude earthquakes and seismic sequences frequently develop on fault systems, but whether they are linked to future major ruptures is always ambiguous. In this study, we investigated a seismic sequence that has developed within a portion of the stretching region of the Apennines in Italy where moderate to large earthquakes are likely to occur. We captured a total of 2039 aftershocks of the 2023 September 18, Mw 4.9 earthquake occurred during the first week, by using machine-learning (ML) based algorithms. Aftershocks align on two 5–7 km long parallel faults, from a length that exceeds what is expected from the main shock magnitude. The segments are ramping at about 6 km depth on closely spaced N100 striking 70 N dipping planes, at a distance of some kilometres from the main shock hypocentre. Our results indicate that even moderate magnitude events trigger seismicity on a spread set of fault segments around the main shock hypocentre, revealing processes of interaction within the crustal layer. The possibility that larger earthquakes develop during seismicity spread is favoured by pore pressure diffusion, in relation with the closeness to criticality of fault segments. Based on the very rapid activation of seismicity on the entire system and a back-front signal from the hypocentre of the main event, we infer that fluid pressure, initially high within the crustal layer, rapidly dropped after the main shock. Our study reinforces the importance of timely extracting information on fault geometry and seismicity distribution on faults. ML-based methods represent a viable tool for semi-real-time application, yielding constraints on short-time forecasts.Published99–111OST3 Vicino alla fagliaJCR Journa
International Conference on Marine Data and Information Systems - Proceedings Volume
No full textThe IMDIS cycle of conferences has the aim of providing an overview of the existing information systems to serve different users in ocean science. It also shows the progresses on development of efficient: infrastructures for managing large and diverse data sets, standards, interoperable information systems, services and tools for education.
The Conference will present different systems for online access to data, metadata and products, communication standards and adapted technology to ensure platforms interoperability. Sessions will focus on infrastructures, technologies and services for different users: environmental authorities, research, schools, universities, etc.PublishedBergen (Norway)OSA4: Ambiente marino, fascia costiera ed Oceanografia operativ
Reappraising the 25 February 1695 Asolano Earthquake
No full textThe 1695 Asolano earthquake (Mw 6.4) is the southernmost of the six largest earthquakes to have occurred in NE Italy or nearby (the others being: 1348, Mw 6.6, Eastern-Alps; 1511, Mw 6.3, Friuli-Slovenia; 1873, Mw 6.2, Alpago-Cansiglio; 1936, Mw 6.1, Alpago-Cansiglio; 1976, Mw 6.4, Friuli). The 1695 earthquake is generally associated with the Montello thrust, most recent studies locating it on the eastern slope of the Montello hill. A full-scale reappraisal of all available historical data leads this study to a more robust macroseismic localization of the 1695 earthquake and to open toward other possible locations of the seismic source that produced it. In particular, it becomes feasible to place its epicenter at the foothills of the Monte Grappa massif, the major morphological expression of the Bassano-Valdobbiadene thrust fault. Here we describe the reasons that make this fault a possible alternative to previous hypotheses.Published526–538OST2 Deformazione e Hazard sismico e da maremotoJCR Journa
Evaluation of the b Maps on the Faults of the Major (M > 7) South California Earthquakes
No full textWe use the Godano et al. (2022, https://doi.org/10.1029/2021ea002205) method for evaluating the b maps of the faults associated with the largest earthquakes M ≥ 7.0 that occurred in California. The method allows an independent evaluation of the b parameter, avoiding the overlap of the cells and the omission of some earthquakes, while keeping all the available information in the catalog. We analyzed four large earthquakes: Landers, Hector Mine, Baja California, and Searles Valley. The maps obtained confirm that the b value can be considered as a strain meter and allow us to elucidate the presence of barriers, such as obstacles to the propagation of the fracture, on the fault of the analyzed earthquakes. A further estimated parameter is the time window during which aftershocks occur in the cell, Δt. This quantity is very useful for a better definition of the aftershock generation mechanism. It reveals where the stress is released in a short time interval and how the complexity of the faulting process controls the occurrence of aftershocks on the fault, and also the duration of the entire sequence.Publishede2023EA002933JCR Journa
Genere e rischi naturali: un percorso di ricerca
No full textNell’occasione del Ventennale dell’Associazione Donne e Scienza, il presente contributo riassume un percorso di ricerca scaturito dalla partecipazione attiva all’Associazione per circa un decennio e che si snoda via via, corroborato dalle strategie di eguaglianza di genere a livello nazionale e internazionale. Viene affrontato il tema delle dimensioni di
genere nei rischi naturali, come emerso nell’ambito progetto INGV DiGeST (2022-2024). I fenomeni naturali sono neutri, ma gli impatti non lo sono. Le diseguaglianze nella società, e in particolare quelle di genere, sono determinanti nel delineare i rischi e gli impatti degli eventi naturali. È necessario includere il genere nei contenuti di ricerca, educazione, rapporti scienza-società, ed è necessario farlo per realizzare una ricerca di qualità. Comprendere come le relazioni di genere modellino la vita delle donne e degli uomini è fondamentale per la riduzione del rischio.Published89-97OS: Terza mission
DC_OCEAN: an open-source algorithm for identification of duplicates in ocean databases
No full textA high-quality hydrographic observational database is essential for ocean and climate studies and operational applications. Because there are numerous global and regional ocean databases, duplicate data continues to be an issue in data management, data processing and database merging, posing a challenge on effectively and accurately using oceanographic data to derive robust statistics and reliable data products. This study aims to provide algorithms to identify the duplicates and assign labels to them. We propose first a set of criteria to define the duplicate data; and second, an open-source and semi-automatic system to detect duplicate data and erroneous metadata. This system includes several algorithms for automatic checks using statistical methods (such as Principal Component Analysis and entropy weighting) and an additional expert (manual) check. The robustness of the system is then evaluated with a subset of the World Ocean Database (WOD18) with over 600,000 in-situ temperature and salinity profiles. This system is an open-source Python package (named DC_OCEAN) allowing users to effectively use the software. Users can customize their settings. The application result from the WOD18 subset also forms a benchmark dataset, which is available to support future studies on duplicate checks, metadata error identification, and machine learning applications. This duplicate checking system will be incorporated into the International Quality-controlled Ocean Database (IQuOD) data quality control system to guarantee the uniqueness of ocean observation data in this product.Published1403175OSA4: Ambiente marino, fascia costiera ed Oceanografia operativaJCR Journa
Ionospheric response to the 2020 Samos earthquake and tsunami
No full textOn 30 October 2020 at 11:51 UT, a magnitude 7.0 earthquake occurred in the Dodecanese sea (37.84°N, 26.81°E, 10 km depth) and generated a tsunami with an observed run-up of more than 1 m on the Turkish coasts. Both the earthquake and the tsunami produced acoustic and gravity waves that propagated upward, triggering co-seismic and co-tsunamic ionospheric disturbances. This paper presents a multi-instrumental study of the ionospheric impact of the earthquake and related tsunami based on ionosonde data, ground-based Global Navigation Satellite Systems (GNSS) data and data from DORIS beacons received by Jason3 in the Mediterranean region. Our study focuses on the Total Electron Content to describe the propagation of co-seismic and co-tsunami ionospheric disturbances (CSID, CTID), possibly related to gravity waves triggered by the earthquake and tsunami. We use simultaneous vertical ionosonde soundings to study the interactions between the upper and lower atmosphere, highlighting the detection of acoustic waves generated by the seismic Rayleigh waves reaching the ionosonde locations and propagating vertically up to the ionosphere. The results of this study provide a detailed picture of the Lithosphere-Atmosphere–Ionosphere coupling in the scarcely investigated Mediterranean region and for a relatively weak earthquake.Published13OST1 Alla ricerca dei Motori GeodinamiciOSA3: Climatologia e meteorologia spazialeJCR Journa
A comparison of intensity prediction equations for Italy
No full textMacroseismic intensity data continue to be fundamental for the assessment of seismic hazard and
risk, despite the progress achieved in the last century by instrumental seismology. This study aims at
comparing a new macroseismic intensity attenuation model and relationships between Ground Motion
Parameters (GMPs) and macroseismic intensity for Italy. The considered macroseismic intensity attenuation
model for Italy was calibrated in Mw: a selected set of 119 Italian shallow tectonic earthquakes, that occurred
between 1908-2013 with instrumentally recorded magnitude (Mw) and 16.260 Intensity Data Points (IDPs),
were used to calibrate its coefficients. This set of data was selected on the basis of magnitude range, spatial
distribution, quality of instrumental moment magnitude [3.8-7.1], epicentral locations, and intensity range. The
calibrated model was tested on an independent set of 15 post-1900 earthquakes. From the set of empirical
relationships between macroseismic intensity and GMPs published by Gomez-Capera et al. (2020) for the
Italian territory, in the present study we considered the relationship in PGA. This non-linear model was
calibrated using 240 macroseismic intensity-GMP pairs from 67 Italian earthquakes occurred in the time
window 1972-2016, with Mw ranging from 4.2 to 6.8 and macroseismic intensity in the range [2, 10-11]. Ninety
percent of the interdistance between macroseismic observations and strong-motion stations is within 2 km.
The results of the comparison show that both models provide useful insights into macroseismic intensity
attenuation models for Italy, offering different levels of sensitivity to physical parameters. By combining the two
models, it is possible to make more accurate predictions of macroseismic intensity, as well as to compare
macroseismic intensity with GMP estimates of seismic hazard, highlighting the fundamental contribution of the
macroseismic intensity data to the seismic hazard and risk assessment.PublishedMiCo - Milano Convention Centre, Milan, ItalyOST2 Deformazione e Hazard sismico e da maremot
On the still unpredictable but recurrent lahars: the November 26, 2022 case study at Ischia island (Italy)
No full textLahars, landslides and debris flows are rapid natural phenomena that can heavily impact on and modify the environment, not only that from which they are triggered but also the one in which they propagate or leave deposits. In particular, lahars can reach significant runout distances from source areas (e.g., several km) and this can mainly depend, among other factors, on the morphology experienced by such propagation. There are cases in the recent history of natural occurrences in which lahars impacted catastrophically on rural and urban settings, such as for example at Nevado del Ruiz volcano (Colombia) in 1985 causing the death of thousands of people living around there. A more recent event occurred on November 26, 2022 at Ischia island (Italy), which is an active volcano particularly subjected to the recurrence of these phenomena. In this case, the emplacement of some lahars caused the death of a few tens of people and the damaging of tens of building, besides the direct impact on local agriculture and tourism. In the nearby Neapolitan volcanic area, several other lahar events occurred in the historical past, not only during but also after or well after explosive eruptions, as the evidence that these phenomena are still to be considered as complex and often unpredictable extreme natural events, also exacerbated by the climate changes, but also that they have some recurrence that cannot be neglected. Such kind of recurrence is mainly related to the local weather, which can even affect the intrinsic behavior of the flows that detach from the source areas and invade the territory. On the other hand, this is not a strictly statistical issue, as there are instrumental measurements that support the fact that heavy rains can exacerbate a landscape already prone to sliding, avalanching, and other catastrophic phenomena. For this, the November 26, 2022 Ischia case study was chosen with the goal of reconstructing the physical features that led to the lahar generation and invasion, which is something that might occur in the future but that should be experienced with a dedicated scientific and territorial consciousness. What was done is an integration of multidisciplinary approaches, corroborated by data from the INGV-OV monitoring network installed on the volcano, capable of detecting the otherwise lost flow timing and dynamical behavior. In particular, the seismic evidence that accompanied the Ischia lahar events, along with the consideration of some lithological features leading to an estimation of flow velocity and dynamic pressure, allow to discriminate multiple lahar pulses over the early morning of November 26, 2022. The main findings of this contribution are that the potential of the Ischia lahars had a sort of recharge timespan which depended on the local weather and lithological features, while the threshold of the lahar trigger depended on the hydrogeological conditions. The seismic reconstruction of the entire event allowed to quantify the first of these two critical issues at Ischia island.PublishedViennaOSV1: Verso la previsione dei fenomeni vulcanici pericolos