ALBERT

Description: This work focuses on the observation of data recorded by the seismic temporary network installed in the Amatrice area, under the umbrella of the Italian Center for Seismic Microzonation (http://www.centromicrozonazionesismica.it), following the M 6.0 earthquake of August 24, 2016 in Central Italy. The aim was studying the presence of an evident late low frequency wave packet observed in some of the recorded aftershocks. In order to interpret this phenomenon, we combined a beam-forming analysis performed on these data with the statistics on residuals of localizations related to the same events, recorded by the Italian Seismic Network (RSN). The total number of analyzed events, characterized by M≥=3 and epicentral distances between 30 and 55 Km, is 356. By observing the seismic traces of these events there was an evidence, in some of them, of a low frequency packet appearing 10 seconds after the first arrival. The evidence of this packet was correlated with epicentral distance and focal depth. For a subset of stations, considered as an array, a beam-forming analysis was performed by using the ObsPy toolbox (M. Beyreuther et al., 2010). Results of this analysis gave information in terms of slowness and azimuth to distinguish the main seismic phases of the considered events. In addition, by using locations of the RSN records (Chiaraluce et al., 2017), we performed a parallel analysis within the subset of events with clear evidence of the low frequency packet. We relocated these events by using the NonLinLoc code, with a fixed 1D P-wave velocity model, and varying the Vp/ Vs ratio in the range 1.6–2.0. We found that the P phases residuals are not influenced by the Vp/Vs ratio changes whereas the higher the Vp/Vs the lower are the S phases residuals. Higher values of Vp/Vs ratio, fixing Vp values, could mean a decrease of Vs connected to particular effects during the seismic waves path, that are probably due to geological heterogeneities at local or larger scale

Description: Published

Description: Miami, Florida

Description: 5T. Sismologia, geofisica e geologia per l'ingegneria sismica

Description: The aim of scientific dissemination is to spread interest and knowledge of scientific issues by trying to reach people of all ages and social backgrounds. Simplifying, without trivializing, scientific concepts and making them attractive to the general public is therefore essential to achieve the previous objectives. For this purpose, it can be useful for scientists to work in close collaboration with artists, implementing new tools that can positively influence the emotional sphere and capture the attention of the people involved. Playful educational activity and visual language play a key role in this process, to convey interest and facilitate learning. An example of this approach are the educational laboratories structured as group games, in which great importance is given both to practical activities and to the transmission of concepts through their visualization in the form of images. Over the last 8 years, the Istituto Nazionale di Geofisica e Vulcanologia (National Institute of Geophysics and Volcanology, INGV), the Istituto di Scienze Marine del Consiglio Nazionale delle Ricerche (Institute of Marine Sciences of the National Research Council, CNR-ISMAR) and the Historical Oceanography Society (HOS) have collaborated in the organization of science dissemination events involving students from schools of different levels participating in educational experiences based on games, characterized by an essentially visual approach to the concepts presented. In this work, we would like to give a brief overview of these educational tools, retracing the choices made while ideating them, thanks mainly to the close collaboration with artists and illustrators.

Description: Published

Description: 179–190

Description: 2TM. Divulgazione Scientifica

Description: N/A or not JCR

Description: In recent years, great efforts have been devoted to the study of the human-induced earthquakes, owing to the effect that these earthquakes can have in terms of seismic hazard. In the past, different authors proposed classification schemes for distinguishing different mechanisms for fluid-induced seismicity generation (see, e.g. McGarr 2000). For example, it has been suggested that when the anthropic activities are responsible for a very small part of the stress field perturbations, the seismic events can be classified as “triggered”, while when the anthropic activities are responsible for the most of stress perturbations driving to the event occurrence, it can be classified as “induced”. In practice, we can rather consider that it may exist a continuum of cases depending on both the characteristics of technological operations and the local stress state.

Description: Ministero di Sviluppo Economico, Direzione Generale per le Infrastrutture e la Sicurezza dei Sistemi Energetici e Geominerari (DG ISSEG)

Description: Published

Description: Bologna

Description: 6T. Studi di pericolosità sismica e da maremoto

Description: A total of 4991 ionograms recorded from April 1997 to December 2017 by the Millstone Hill Digisonde (42.6°N, 288.5°E) were considered, with simultaneous Ne(h)[ISR] profiles recorded by the co-located Incoherent Scatter Radar (ISR). The entire ionogram dataset was scaled with both the Autoscala and ARTIST programs. The reliability of the hmF2 values obtained by ARTIST and Autoscala was assessed using the corresponding ISR values as a reference. Average errors Δ and the root mean square errors RMSE were computed for the whole dataset. Data analysis shows that both the Autoscala and ARTIST systems tend to underestimate hmF2 values with |Δ| in all cases less than 10 km. For high magnetic activity ARTIST offers better accuracy than Autoscala, as evidenced by RMSE[ARTIST] 〈 RMSE[Autoscala], under both daytime and nighttime conditions, and considering all hours of the day. Conversely, under low and medium magnetic activity Autoscala tends to estimate hmF2 more accurately than the ARTIST system for both daytime and nighttime conditions, when RMSE[Autoscala] 〈 RMSE[ARTIST]. However, RMSE[Autoscala] slightly exceeds RMSE[ARTIST] for the day as a whole. RMSE values are generally substantial (RMSE 〉 16 km in all cases), which places a limit on the results obtainable with real-time models that ingest ionosonde data.

Description: Published

Description: id 2671

Description: 2A. Fisica dell'alta atmosfera

Description: JCR Journal

Description: Ionospheric characteristics and crustal earthquakes that occurred in 2016 next to the town of Amatrice, Italy are studied together with the previous events that took place from 1984 to 2009 in Central Italy. The earthquakes with M larger than 5.5 and epicentral distances from the ionosonde less than 150 km were selected for the analysis. A multiparametric approach was applied using variations of sporadic E-layer parameters (the height and the transparency frequency) together with variations of the F2 layer critical frequency foF2 at the Rome ionospheric observatory. Only ionospheric data under quiet geomagnetic conditions were considered. The inclusion of new 2016 events has allowed us to clarify the earlier-obtained seismo-ionospheric empirical relationships linking the distance in space (km) and time (days) between the ionospheric anomaly and the impending earthquake, with its magnitude. The improved dependencies were shown to be similar to those obtained in previous studies in different parts of the world. The possibility of using the obtained relationships for earthquake predictions is discussed.

Description: Published

Description: id 354

Description: 2A. Fisica dell'alta atmosfera

Description: JCR Journal

Description: The identification and characterization of seismogenic structures in southwestern Sicily is an open debate both for the geological-structural complexity of this sector and the scarce seismicity as well. In addition, clear morphological evidence of tectonic structures is limited. Besides the geophysical methods, the study of the spatial distribution of soil CO2 flux is a valid methodology to investigate the position and geometry of buried active faults. Indeed, active tectonic structures are channels with high permeability through which deep fluids can migrate toward the atmosphere. Therefore, the alignment of high degassing areas can reveal the presence of preferential ways of rising fluids (i.e. faults). We applied this methodology in SW Sicily in the surrounding of the area hit by the 1968 seismic sequence and in three other areas where evidence of active deformation has been recognized. Furthermore, to investigate the origin of emitted fluids, we measured the carbon isotopic composition of the soil CO2 in some high emission sites. The results showed high spatial variability of soil CO2 fluxes with values ranging from 1 to 430 g m−2d−1. The areal patterns of soil CO2 fluxes in all the areas reveal a strong influence of the main tectonic structures and active deformations on soil CO2 emissions. The range of isotopic data and the distribution of soil CO2 fluxes suggest a supply of deep fluids through the active tectonic structures.

Description: Published

Description: SE104

Description: 2T. Deformazione crostale attiva

Description: 6A. Geochimica per l'ambiente e geologia medica

Description: JCR Journal

Description: Paleo-thermometers in sedimentary basins often drive to misleading thermal modelling when applied alone or only on potentially productive Paleozoic source rocks. Different paleo-thermal and thermo-chronological data have been used as constraints to model the Silurian to Cenozoic succession of a recently drilled well in the onshore portion of the Baltic Basin, in northern Poland. This dataset provides an integrated platform for thermal maturity assessment contributing to the highly debated reconstruction of the thermal history of the Baltic Basin in the last decade. The well stratigraphy consists of a Lower Paleozoic marine clayey and arenaceous/calcareous succession, about 1000 m thick that is unconformably overlain by a 2000 m thick Permian to Cenozoic sequence, developed in a continental to shallow marine environment. Optical microscopy, FT-IR and Raman spectroscopy analysis of organic matter have been coupled with (U–Th)/He data to produce a robust vitrinite reflectance profile and constrain the 1D thermal modelling of the well. In addition, such a thermal maturity profile was validated by an independent thermal modelling calibrated by the smectite illitization kinetics. Both models identify high heat flow conditions (up to 1.7 HFU) at the end of Mesozoic. The Lower Paleozoic succession entered the late oil window of HC generation during this last heating event.

Description: Published

Description: 104547

Description: 1TR. Georisorse

Description: JCR Journal

Description: The Einstein Telescope (ET) is a proposed next-generation, underground gravitational-wave detector to be based in Europe. It will provide about an order of magnitude sensitivity increase with respect to the currently operating detectors and, also extend the observation band targeting frequencies as low as 3 Hz. One of the first decisions that needs to be made is about the future ET site following an in-depth site characterization. Site evaluation and selection is a complicated process, which takes into account science, financial, political, and socio-economic criteria. In this paper, we provide an overview of the site-selection criteria for ET, provide a formalism to evaluate the direct impact of environmental noise on ET sensitivity, and outline the necessary elements of a site-characterization campaign.

Description: Published

Description: 094504

Description: 6IT. Osservatori non satellitari

Description: JCR Journal

Description: Recent strontium isotope (87Sr/86Sr) analyses of bones and teeth have provided useful archeological results for reconstructing past human migration and diet. We report 87Sr/86Sr ratios and DNA analyses of tooth enamel from individuals buried in some necropolises in Nola town, near Napoli (Campania, South Italy). These individuals lived in the period between the Avellino (1925 years BCE) and CE 472 Pollena Vesuvian eruptions and are dated on archeological basis to the time span between the sixth and second century BCE. Tooth enamel 87Sr/86Sr ratios (0.70788–0.70864) are higher than baseline values in the necropolises (0.70756–0.70792): this can be explained by assuming either that all the analyzed individuals are not local—an unlikely possibility—or that they ate both local and foreign food (within about 50 km), including 87Sr-rich seafood. An explanation for such a varied diet might be that the individuals from Nola were living near the Ancient Appia and Popilia ways and not far from the coastline. Whatever its origin, the 87Sr/86Sr ratios represent the isotopic signature of the local community living on the slopes of Mt. Somma-Vesuvius between the sixth and second centuries BCE. This knowledge will support future isotope studies on volcanic eruptions as possible causes of human migration.

Description: Published

Description: id 157

Description: 1V. Storia eruttiva

Description: 3V. Proprietà chimico-fisiche dei magmi e dei prodotti vulcanici

Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio

Description: JCR Journal

Description: DOWNFLOW is a probabilistic code for the simulation of the area covered by lava flows. This code has been used extensively for several basaltic volcanoes in the last decade, and a review of some applications is presented. DOWNFLOW is based on the simple principle that a lava flow tends to follow the steepest descent path downhill from the vent. DOWNFLOW computes the area possibly inundated by lava flows by deriving a number, N, of steepest descent paths, each path being calculated over a randomly perturbed topography. The perturbation is applied at each point of the topography, and ranges within the interval +Dh. N and Dh are the two basic parameters of the code. The expected flow length is constrained by statistical weighting based on the past activity of the volcano. The strength of the code is that: (i) only limited volcanological knowledge is ecessary to apply the code at a given volcano; (ii) there are only two (easily tunable) input parameters; and (iii) computational requirements are very low. However, DOWNFLOW does not provide the progression of the lava emplacement over time. The use of DOWNFLOW is ideal when a large number of simulations are necessary: for example, to compile maps for hazard and risk-assessment purposes.

Description: Published

Description: 293-312

Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio

Description: We compare differences and similarities in the annual stratospheric HNO3 cycle derived from ground‐based measurements at the South Pole during 1993 and 1995, after correcting an error in earlier published profile retrievals for 1993 which led to under estimation of mixing ratios. The data series presented here provide profiling over the range ∼16–48 km, and cover the fall‐winter‐spring cycle in the behavior of HNO3 in the extreme Antarctic with a large degree of temporal overlap. With the exception of one gap of 20 days, the combined data sets cover a full annual cycle. The record shows an increase in HNO3 above 30 km occurring about 20 days before sunset, which appears to be the result of higher altitude heterogeneous conversion of NOx as photolysis diminishes. Both years show a strong increase in HNO3 beginning about polar sunset, in a layer peaking at about 25 km, as additional NOx is heterogeneously converted to nitric acid. When temperatures drop to the polar stratospheric cloud (PSC) formation range near the end of May, gas phase HNO3 is rapidly reduced in the lower stratosphere, although at least 2–3 weeks of temperatures ≤192 K appear to be required to complete most of the gas‐phase removal at the upper end of the depletion range (22–25 km). Despite a significant difference in residual sulfate loading from the explosion of Mount Pinatubo, there appears to be little gross difference in the timing and effects of PSC formation in removing gas phase HNO3 in these 2 years, though removal may be more rapid in 1995. Incorporation of gas phase HNO3 into PSCs appears to be nearly complete up to ∼25 km by midwinter. We also see a repeat of the formation of gas phase HNO3 in the middle stratosphere in early midwinter of 1995 with about the same timing as in 1993, suggesting that this phenomenon is driven by a repetition of dynamical transport and appropriate temperatures and pressures in the polar night, and not (as has been suggested) by ion‐based heterogeneous chemistry that requires triggering by large relativistic electron fluxes. High‐altitude HNO3 production peaks during a period of ∼20 days, but appears to persist for up to ∼40 days in the 40–45 km range, ceasing well before sunrise. This HNO3 descends rapidly throughout the production period, at a rate in good agreement with theoretically determined midwinter subsidence rates. As noted in earlier studies, later warming of this region above PSC evaporation temperatures does not cause reappearance of large amounts of HNO3, indicating that most PSCs gravitationally sink out of the stratosphere before early spring. We present evidence that smaller PSCs do evaporate to ∼1 to 3.5 ppbv of HNO3 in the lower stratosphere, however, working downward from ∼25 km as temperatures rise during the late winter. There is a delay of ∼15 days after sunrise before photolysis causes significant depletion in the altitude range below ∼30 km, where subsidence has carried virtually all higher‐altitude HNO3 by polar sunrise. Some continued subsidence and photolysis combine to keep mixing ratios less than ∼5 ppbv below 30 km until the final breakdown of the vortex in November brings larger amounts of HNO3 with air from lower latitudes.

Description: Published

Description: 17739-17750

Description: 5A. Ricerche polari e paleoclima

Description: JCR Journal

Description: The vulnerability assessment on large areas was carried out on residential buildings adopting a statistical approach that has been developed for this purpose. In fact, even though the method for evaluating single buildings vulnerability is quite well defined, it cannot be applied to large areas, not only because it would cost too much in money and time to survey each building, but also because the result would be useless at this scale, where the information needed for decision making is less detailed. Census data are a primary source in this case: they cover homogeneously the whole country though the information they provide permits only to estimate the total number of buildings, the total volume and a poor classification in terms of age and few typological parameters. The collection and review of available data regarding previous buildings vulnerability surveys performed by GNDT and census archives has been organised inside a database for the calibration of buildings vulnerability functions in the investigated area. The vulnerability evaluation for all Italian municipalities has been performed as a weighted mean of the average vulnerability index for each census classes.

Description: Published

Description: 105-131

Description: 5T. Sismologia, geofisica e geologia per l'ingegneria sismica

Description: The Italian Present-day Stress Indicators (IPSI) database is a freely available Italian georeferenced repository of information regarding the crustal stress field. It consists of horizontal stress orientations that have been analysed, compiled in a standardised format and quality-ranked for reliability and comparability on a global scale. The database contains a collection of information regarding contemporary stress within the shallow crust from the following main stress-indicator categories: borehole breakouts; earthquake focal mechanisms; seismic sequences and active fault-slip data. The present database (IPSI 1.4) released in January 2020 is accessible through a web interface which facilitates findability, accessibility, interoperability and reusability of the dataset. Moreover, it contains 928 records updated up until December 2019 with an increase of 10% with respect to the first one, and improved metadata information. The uniform spread of stress data over a given territory is relevant for earth crustal modelling or as starting point in many applied studies. It is therefore necessary to continue collecting new data and update present-day stress maps to obtain more reliable evaluations.

Description: Published

Description: id 298

Description: 2T. Deformazione crostale attiva

Description: 4IT. Banche dati

Description: JCR Journal

Description: Establishing sustainable and responsible speleotourism development is a major challenge and involves complex activities. Adequate theoretical starting point is the application of geoethical values related to the conservation and protection of the caves to be used for touristic purposes. Positive and negative cases of human behaviors towards speleological geoheritage are discussed, in order to highlight what should be done in cave management to avoid malpractices and on what elements could be founded adequate strategies aimed at promoting sustainable speleotourism. This is important to tourism management organizations involved in the promotion of caves and in creating economic opportunities for local populations, while respecting cave ecosystems. Modern cave management must be focused on the protection of the cave ecosystems, finding ways to achieve at the same time an economic development of local communities. But this approach needs the adoption of a geoethical framework of values to be shared by all stakeholders involved so that successful cooperation can be achieved despite differences in interests and expectations. The aim of this paper is to raise the awareness about the need to apply the values of geoethics to speleotourism, stimulating new fields of discussion within the scientific and technical communities involved in studies and activities related to geotourism and geoheritage. The possibilities of developing new ways to manage caves, in order to promote a sustainable socio-economic development of local communities, have to be balanced with the protection of natural environments as much as possible. The proposed theoretical frameworks have the goal to increase the discussion on the best ways of connecting speleotourism to sustainable and responsible cave management, presenting two case studies, and pointing out potential solutions.

Description: Open access funding provided by Istituto Nazionale di Geofisica e Vulcanologia within the CRUI-CARE Agreement

Description: Published

Description: id 73

Description: 7SR AMBIENTE – Servizi e ricerca per la società

Description: 1TM. Formazione

Description: 2TM. Divulgazione Scientifica

Description: JCR Journal

Description: Fluids are pervasive in fault zones cutting the Earth's crust; however, the effect of fluid viscosity on fault mechanics is mainly conjectured by theoretical models. We present friction experiments performed on both dry and fluid-permeated silicate and carbonate bearing-rocks, at normal effective stresses up to 20 MPa, with a slip-rate ranging between 10 μm/s and 1 m/s. Four different fluid viscosities were tested. We show that both static and dynamic friction coefficients decrease with viscosity and that dynamic friction depends on the dimensionless Sommerfeld number (S) as predicted by the elastohydrodynamic-lubrication theory (EHD).Under favourable conditions (depending on the fluid viscosity (η), co-seismic slip-rate (V), fault geometry (L/H02) and earthquake nucleation depth (∝σeff)), EHD might be an effective weakening mechanism during natural and induced earthquakes. However, at seismic slip-rate, the slip weakening distance (Dc) increases markedly for a range of fluid viscosities expected in the Earth, potentially favouring slow-slip rather than rupture propagation for small to moderate earthquakes.

Description: Published

Description: 1274

Description: 3T. Sorgente sismica

Description: 2IT. Laboratori analitici e sperimentali

Description: JCR Journal

Description: Escape Volcano is a new scientific game that, through a path made of boxes, allows children andteenagers to question themselves and learn about issues related to the Earth Sciences and the risksassociated.The game is the brainchild of the INGV researchers of Rome who designed it, in close collaborationwith students from two third­year classes at the “Primo Levi” Scientific High School in Rome, as partof the Alternanza Scuola Lavoro (hereafter ASL) project “Life as a Researcher”; this educational­ludicsociety game deals, with the basic knowledge of volcanoes and earthquakes, providing ideas for themitigation of the risks associated with them, with purpose of environmental protection. In thefollowing will be illustrate the different phases that led the transformation of the original idea in toa project, as well as the realization of the “Prototype 00” carried out in the laboratories of the INGV.During the planning phase, the game was designed for boys of secondary school.The results obtained during this test phase, that was carried out for a year in various scientific events,allowed gathering excellent hints, in the terms of scientific content and rules. These advices permittedto improve the game fluidity and made it accessible for players of all ages, as well as for childrenwith different types of disabilities that necessitate special attention.

Description: Istituto Nazionale di Geofisica e Vulcanologia

Description: Published

Description: 1-34

Description: 1TM. Formazione

Description: 2TM. Divulgazione Scientifica

Description: 3TM. Comunicazione

Description: N/A or not JCR

Description: Questa nota descrive i diversi luoghi d’Italia attraversati da Giuseppe Mercalli ripercorrendo il percorso scientifico di questo famoso studioso, che, attraverso la meticolosa descrizione dei più disparati fenomeni naturali, era alla continua ricerca della loro spiegazione, classificazione e quantificazione. Questa sua continua ricerca lo portò ad approfondire, tra l’altro, tematiche vulcanologiche e sismologiche e ad inserirsi brillantemente nel dibattito scientifico dell’epoca. Di notevole rilievo furono anche la sua attività come insegnante e la sua produzione scientifica e “didattica”. Infatti egli non abbandonò mai l’insegnamento delle Scienze Naturali, che lo portò ad attraversare l’Italia e a dotare i propri allievi di libri di testo di notevole valore e accuratezza [Mercalli, 1883a; Mercalli, 1883b; Mercalli, 1883c; Mercalli, 1883d; Mercalli, 1883e; Mercalli, 1907]. Giuseppe Mercalli nacque a Milano il 20 Maggio del 1850, da Carlo e da Carolina De Simone, artigiani tessili della seta. Terzogenito di cinque figli, iniziò privatamente i suoi studi, proseguendo quelli liceali nel Seminario di Monza per la cultura letteraria e scientifica, e quelli teologici nel Seminario Maggiore di Milano, dove ricevette l’ordinazione sacerdotale il 20 dicembre 1872 (Fig. 1). Nella Sezione Normale del Politecnico milanese, Mercalli frequentò le lezioni del corso di Scienze Naturali tenute dal geologo abate Antonio Stoppani. Qui ottenne nel 1874 il diploma di insegnante di Scienze Naturali.

Description: Published

Description: 40-49

Description: 2TM. Divulgazione Scientifica

Description: N/A or not JCR

Description: La valorizzazione del territorio passa necessariamente attraverso la possibilità di mettere in luce le eccellenze che lo rendono un patrimonio unico attraverso l'integrazione tra di esse.....

Description: Published

Description: 1-16

Description: 2TM. Divulgazione Scientifica

Description: Nitrogen is the main constituent of the Earth's atmosphere, but its provenance in the Earth's mantle remains uncertain. The relative contribution of primordial nitrogen inherited during the Earth's accretion versus that subducted from the Earth's surface is unclear1-6. Here we show that the mantle may have retained remnants of such primordial nitrogen. We use the rare 15N15N isotopologue of N2 as a new tracer of air contamination in volcanic gas effusions. By constraining air contamination in gases from Iceland, Eifel (Germany) and Yellowstone (USA), we derive estimates of mantle δ15N (the fractional difference in 15N/14N from air), N2/36Ar and N2/3He. Our results show that negative δ15N values observed in gases, previously regarded as indicating a mantle origin for nitrogen7-10, in fact represent dominantly air-derived N2 that experienced 15N/14N fractionation in hydrothermal systems. Using two-component mixing models to correct for this effect, the 15N15N data allow extrapolations that characterize mantle endmember δ15N, N2/36Ar and N2/3He values. We show that the Eifel region has slightly increased δ15N and N2/36Ar values relative to estimates for the convective mantle provided by mid-ocean-ridge basalts11, consistent with subducted nitrogen being added to the mantle source. In contrast, we find that whereas the Yellowstone plume has δ15N values substantially greater than that of the convective mantle, resembling surface components12-15, its N2/36Ar and N2/3He ratios are indistinguishable from those of the convective mantle. This observation raises the possibility that the plume hosts a primordial component. We provide a test of the subduction hypothesis with a two-box model, describing the evolution of mantle and surface nitrogen through geological time. We show that the effect of subduction on the deep nitrogen cycle may be less important than has been suggested by previous investigations. We propose instead that high mid-ocean-ridge basalt and plume δ15N values may both be dominantly primordial features.

Description: Published

Description: 367–371

Description: 3V. Proprietà chimico-fisiche dei magmi e dei prodotti vulcanici

Description: JCR Journal

Description: Vulcano is one of the 7 volcanic islands and 6 seamounts forming the Aeolian volcanic district (Italy). Vulcano has a long eruptive record, and its last eruption (1888–90 AD) originated the definition of the Vulcanian eruptive style. Like most volcanic islands, Vulcano generates many potentially interconnected hazards, determining a potentially high risk. Here, we review the state of knowledge on its geology, eruptive activity, historical accounts, structural setting, geophysical and geochemical surveillance, and available hazard assessment, in order to have an updated picture of the state knowledge on volcanic hazard. We follow a prototypal reviewing scheme, based on three standardized steps: i) review of the volcanic system; ii) review of available eruptive and noneruptive hazard quantifications; iii) development of a conceptual interpretative model. We find that, while a rather vast literature is dedicated to the volcanic system of Vulcano and the reconstruction of past events, few quantitative hazard assessments exist. In addition, the range of natural variability considered for each hazard is potentially underestimated (e.g. limited range of considered eruption magnitude and style and of vent position), as it is the potential effect of multi-hazard impact. The developed conceptual model for the feeding system provides a synthetic picture of the present knowledge about the system, as emerged from the review. In addition, it allows for the identification of potential paths-to-eruption and provides a first order link among the main hazards. This review provides an up-to-date snapshot of existing knowledge on volcanic hazard at Vulcano on which to build future hazard quantifications as well as to support present and future decision making.

Description: Published

Description: 103186

Description: 1V. Storia eruttiva

Description: JCR Journal

Description: The Italian Government has decreed a series of progressive restrictions to delay the COVID-19 pandemic diffusion in Italy since March 10, 2020, including limitation in individual mobility and the closure of social, cultural, economic and industrial activities. Here we show the lockdown effect in Northern Italy, the COVID-19 most affected area, as revealed by noise variation at seismic stations. The reaction to lockdown was slow and not homogeneous with spots of negligible noise reduction, especially in the first week. A fresh interpretation of seismic noise variations in terms of socio-economic indicators sheds new light on the lockdown efficacy pointing to the causes of such delay: the noise reduction is significant where non strategic activities prevails, while it is small or negligible where dense population and strategic activities are present. These results are crucial for the a posteriori interpretation of the pandemic diffusion and the efficacy of differently targeted political actions.

Description: Published

Description: id 16487

Description: 7A. Geofisica per il monitoraggio ambientale

Description: JCR Journal

Description: The Sea of Galilee in northeast Israel is a freshwater lake filling a morphological depression along the Dead Sea Fault. It is located in a tectonically complex area, where a N-S main fault system intersects secondary fault patterns non-univocally interpreted by previous reconstructions. A set of multiscale geophysical, geochemical and seismological data, reprocessed or newly collected, was analysed to unravel the interplay between shallow tectonic deformations and geodynamic processes. The result is a neotectonic map highlighting major seismogenic faults in a key region at the boundary between the Africa/Sinai and Arabian plates. Most active seismogenic displacement occurs along NNW-SSE oriented transtensional faults. This results in a left-lateral bifurcation of the Dead Sea Fault forming a rhomb-shaped depression we named the Capharnaum Trough, located off-track relative to the alleged principal deformation zone. Low-magnitude (ML = 3-4) epicentres accurately located during a recent seismic sequence are aligned along this feature, whose activity, depth and regional importance is supported by geophysical and geochemical evidence. This case study, involving a multiscale/multidisciplinary approach, may serve as a reference for similar geodynamic settings in the world, where unravelling geometric and kinematic complexities is challenging but fundamental for reliable earthquake hazard assessments.

Description: Published

Description: 11932

Description: 2T. Deformazione crostale attiva

Description: JCR Journal

Description: «In senso oggettivo, il diritto è definibile come il complesso di norme giuridiche che comandano o vietano determinati comportamenti ai soggetti che ne sono destinatari», e pertanto è attraverso esso che la società pone il limite tra il lecito e l’illecito delle azioni umane e stabilisce un regime di sanzioni qualora i comportamenti violino quel limite. Il diritto è il mezzo per mettere in atto e trasformare in agire sociale una precisa visione del mondo e dei rapporti che lo determinano. Affinché l’agire sociale sia consapevole e non coatto, c’è bisogno in primis dell’educazione dei cittadini ai principi e ai valori di riferimento che sono alla base di quella visione del mondo. In tal modo la motivazione di ciò che è lecito diventa comprensibile e rafforza la consapevolezza del significato e dell’importanza di muoversi all’interno di regole e comportamenti ritenuti a vantaggio del singolo e di tutta la comunità. Educare al valore di un’azione rispettosa dell’ambiente è il solo modo per formare cittadini più responsabili, consapevoli che il gesto individuale va a inquadrarsi in una catena di azioni più ampia e articolata, e per accrescere la sensibilità e l’accettazione sociale di nuovi modelli economici più sostenibili. Il diritto sanzionatorio costituisce l’extrema ratio per salvaguardare il perimetro del lecito e in definitiva l’esistenza stessa della comunità, ma non serve a guadagnare consenso consapevole.

Description: Published

Description: 71-82

Description: 1TM. Formazione

Description: 2TM. Divulgazione Scientifica

Description: 3TM. Comunicazione

Description: Gephart and Forsyth's method has been applied to estimate stress orientations from earthquakefa ult planes olutionso f the southwesterAn lps, a regionw heret he tectonic stress regime is known to be fairly complex. Fault plane solutions have been either taken from the literature or computed using data from local and regional networks. Data refer to seismiecv entso f magnitudien the range2 .5-5.3w hicho ccurreidn the iastd ecades at depths between 0 and 25 km. Two zones with a different stress orientation have been identifiedi n the studieda rea (44.0ø-45.ø5 N, 6.5ø-8.5ø E)- the westernz one,c orresponding to the cresto f the alpine belt, where a high-dipm aximumc ompressivset ressi s found, and the easternz one (Alps chaint o Po Plain transition),c haracterizedb y an almosth orizontal E-W al and a nearly vertical as. Hypocenterso f earthquakesu sedf or stressi nversionl ie in the depthr anges0 -15 km and 5-25 km in the westerna nd easternz onesr, espectivelyT. he transitionb etweenth e two st•resdso mainsis very sharp,a nd this is alsoi ndicatedb y sp•ace distributiono f earthquakei ndividualm isfitst o the respectives tressm odels.T he findings of the present study are a good match for tectonic models which assume E-W compression derivedf rom the Adria-Europein teractiona nd producing:( 1) major thrustingp rocesses in the easterns ideo f the chaina nd (2) secondaryte nsionale ffectsa t very shallowd epth beneatht he alpineb elt crest( westernz oneo f the area studiedi n this work).

Description: Published

Description: 8171-8185

Description: 4T. Sismicità dell'Italia

Description: JCR Journal

Description: This is the dataset of the major explosions and paroxysms record at Stromboli from 1879 to 1960, as reconstructed through a detailed review of scientific literature of the last ca. 140 years. The catalog includes the calendar date and phenomena descriptions for 120 explosive events, of which 32 were paroxysms. We summarized the event information content in five columns – (i) noise and earthquakes, (ii) ash plume, (iii) large ejecta, (iv) PDC and tsunami, (v) lava flows. Where possible, the extracts contained the description of any volcanic activity at least one month before the eruption and one month after. The catalog also includes a sequence of extracts from the original literature sources that helped us in the complex characterization of the less recent events. In our analysis, we mostly relied on the detailed characterization of major explosions and paroxysms in Rosi et al. 2013 that provided quantitative constraints on total duration, fallout volume, mass discharge rate, ballistic size, ballistic range and column height of ordinary activity, major explosions, and paroxysms. In several cases, we had to carefully evaluate the original description of the phenomena, due to insufficient quantitative information in the scientific literature. In particular, we considered the area affected by large ballistic projectiles as the discriminant factor to distinguish between ordinary activity, major explosions and paroxysms. This area is limited to the Crater Terrace in case of ordinary activity, to the summit area of the volcano and Sciara del Fuoco during major explosions, and can extend down to low elevations along large part of the island, and sometimes beyond the shoreline, during the paroxysms (Barberi et al., 1993). We also considered several other factors, including the height of the plume, the amount of ash and scoria fallout, the occurrence and strength of any associated shock wave. The occurrence of PDC and/or tsunami associated with the violent explosive activity was assumed as a marker for a paroxysm too(Rosi et al., 2013). The determination of the hour and minute of the explosion in the historical documents usually distinguishes the most violent phenomena. Whilst identifying the paroxysms was relatively straightforward, several possible major explosions were not clearly distinguishable from particularly violent episodes of the ordinary Strombolian activity. Thus, our historical record includes the quantification of the main sources of uncertainty, i.e. the possibility of major explosions of uncertain characterization because of insufficient information. We thus categorized as uncertain 45 major explosions.

Description: INGV

Description: Published

Description: 1V. Storia eruttiva

Description: We propose the energy-dependent magnitude-frequency (EDMF) model as an alternative of the classical (tapered or not) Gutenberg-Richter (G-R) law for the magnitude of seismic events, the most widely used in earthquake forecasting and seismic hazard applications. The model we present is a modification of the Kagan’s tapered G-R law: the corner moment parameter is assumed to be an energy-varying function, changing with respect to the size of the area under analysis, and to the seismic history occurred in the area itself. The basic rationale behind our model rests in the criticism to the applicability of the G-R law on small space-time windows, many times raised in the literature and already tackled for some operational forecasting projects, as for example in the UCERF3 for California. The EDMF model is built in such a way to decrease the probability of large events in a small area where a strong shock has just occurred and to reobtain the classical G-R when enlarging the analyzed region.We do not account for a parental connection between events, neither for an order relation between their magnitudes.We simply condition to the elastic energy available in the area considered, which depends on the time elapsed since the last strong event that is assumed to have resetted the energy available, as well as on the length of the longest fault included in the area. The applicability of the proposed EDMF model is shown for the Californian seismic catalog; we obtain results that support the validity of the EDMF model and its potential to improve large earthquake forecasting at different time scales.

Description: Unpublished

Description: Hakone, Japan

Description: 5T. Sismologia, geofisica e geologia per l'ingegneria sismica

Description: Understanding the processes occurring inside a landfill is important for improving the treatment of landfills. Irrigation and recirculation of leachate are widely used in landfill treatments. Increasing the efficiency of such treatments requires a detailed understanding of the flow inside the landfill. The flow depends largely on the heterogeneous distribution of density. It is, therefore, of great practical interest to determine the density distribution affecting the flow paths inside a landfill. Studies in the past have characterized landfill sites but have not led to high-resolution, detailed quantitative results. We performed an S-wave reflection survey, multichannel analysis of surface waves (MASW), and electrical resistivity survey to investigate the possibility of delineating the heterogeneity distribution in the body of a landfill. We found that the high-resolution S-wave reflection method offers the desired resolution. However, in the case of a very heterogeneous landfill and a high noise level, the processing of high-resolution, shallow reflection data required special care. In comparison, MASW gave the general trend of the changes inside the landfill, whereas the electrical resistivity (ER) survey provides useful clues for interpretation of seismic reflection data. We found that it is possible to localize fine-scale heterogeneities in the landfill using the S-wave reflection method using a high-frequency vibratory source. Using empirical relations specific to landfill sites, we then estimated the density distribution inside the landfill, along with the associated uncertainty considering different methods. The final interpretation was guided by supplementary information provided by MASW and ER tomography.

Description: Published

Description: EN13–EN25

Description: 7A. Geofisica per il monitoraggio ambientale

Description: JCR Journal

Description: Reliable automatic procedure for locating earthquake in quasi-real time is strongly needed for seismic warning system, earthquake preparedness, and producing shaking maps. The reliability of an automatic location algorithm is influenced by several factors such as errors in picking seismic phases, network geometry, and velocity model uncertainties. The main purpose of this work is to investigate the performances of different automatic procedures to choose the most suitable one to be applied for the quasi-real-time earthquake locations in northwestern Italy. The reliability of two automatic-picking algorithms (one based on the Characteristic Function (CF) analysis, CF picker, and the other one based on the Akaike Information Criterion (AIC), AIC picker) and two location methods (“Hypoellipse” and “NonLinLoc” codes) is analysed by comparing the automatically determined hypocentral coordinates with reference ones. Reference locations are computed by the “Hypoellipse” code considering manually revised data and tested using quarry blasts. The comparison is made on a dataset composed by 575 seismic events for the period 2000–2007 as recorded by the Regional Seismic network of Northwestern Italy. For P phases, similar results, in terms of both amount of detected picks and magnitude of travel time differences with respect to manual picks, are obtained applying the AIC and the CF picker; on the contrary, for S phases, the AIC picker seems to provide a significant greater number of readings than the CF picker. Furthermore, the “NonLin- Loc” software (applied to a 3D velocity model) is proved to be more reliable than the “Hypoellipse” code (applied to layered 1D velocity models), leading to more reliable automatic locations also when outliers (wrong picks) are present.

Description: Published

Description: 393–411

Description: 8T. Sismologia in tempo reale

Description: JCR Journal

Description: We develop a mathematical model describing dyke propagation in proximity of an elastic discontinuity of the embedding medium. The dyke is modelled as a fluid-filled crack in plane strain configuration employing the boundary element method. The pressure gradient along the crack is assumed proportional to the difference between the densities of the host rock and the fluid. Mass conservation is imposed during propagation and fluid compressibility is taken into account. The path followed by the crack is found by maximizing the total energy release, given by the sum of the elastic and gravitational contributions. The mathematical simulations provide a sort of ‘refraction phenomenon’, that is a sudden change in the direction of propagation when the crack crosses the boundary separating different rigidities: if the dyke enters a softer medium, its path deviates towards the vertical, if the dyke enters a harder medium its path deviates away from the vertical and may even become arrested as a horizontal sill along the interface, if the rigidity contrast is large. Gravitational energy plays a major role during propagation; in particular, in proximity of layer boundaries, this role is enhanced by the shift of the centre of mass due to changes of dyke shape. Mathematical results were validated by laboratory experiments performed injecting tilted air-filled cracks through gelatin layers with different rigidities.

Description: Published

Description: 1107-1123

Description: 2V. Struttura e sistema di alimentazione dei vulcani

Description: JCR Journal

Description: It has been posited that the 1975–1984 Krafla rifting episode in northern Iceland was responsible for a significant drop in the rate of earthquakes along the Húsavík-Flatey Fault (HFF), a transform fault that had previously been the source of several magnitude 6–7 earthquakes. This compelling case of the existence of a stress shadow has never been studied in detail, and the implications of such a stress shadow remain an open question. According to rate-state models, intense stress shadows cause tens of years of low seismicity rate followed by a faster recovery phase of rate increase. Here, we compare the long-term predictions from a Coulomb stress model of the rifting episode with seismological observations from the SIL catalog (1995–2011) in northern Iceland. In the analyzed time frame, we find that the rift-induced stress shadow coincides with the eastern half of the fault where the observed seismicity rates are found to be significantly lower than expected, given the historical earthquake activity there. We also find that the seismicity rates on the central part of the HFF increased significantly in the last 17 years, with the seismicity progressively recovering from west to east. Our observations confirm that rate-state theory successfully describes the long-term seismic rate variation during the reloading phase of a fault invested by a negative Coulomb stress. Coincident with this recovery, we find that the b-value of the frequency-magnitude distribution changed significantly over time. We conclude that the rift-induced stress shadow not only decreased the seismic rate on the eastern part of the HFF but also temporarily modified how the system releases seismic energy, with more large magnitude events in proportion to small ones. This behavior is currently being overturned, as rift-induced locking is now being compensated by tectonic forcing.

Description: Published

Description: 1109-1121

Description: 5V. Processi eruttivi e post-eruttivi

Description: JCR Journal

Description: Dikes and sills are the moving building blocks of the plumbing system of volcanoes and play a fundamental role in the accretionary processes of the crust. They nucleate, propagate, halt, resume propagation, and sometimes change trajectory with drastic implications for the outcome of eruptions (Sigmundsson et al., 2010). Their dynamics is still poorly understood, in particular when different external influencing factors are interacting. Here we apply a boundary element model to study dike and sill formation, propagation and arrest in different scenarios. We model dikes as finite batches of compressible fluid magma, propagating quasi-statically in an elastic medium, and calculate their trajectories by maximising the energy release of the magma-rock system. We consider dike propagation in presence of density layering, of density plus rigidity layering, of a weakly welded interface between layers, under the action of an external stress field (of tectonic or topographic origin). Our simulations predict sill formation in several situations: i) when a horizontal weak interface is met by a propagating dike; ii) when a sufficiently high compressive tectonic environment is experienced by the ascending dike and iii) in case a dike, starting below a volcanic edifice, propagates away from the topographic load with a low dip angle. We find that dikes halt and stack when they become negatively buoyant and when they propagate with low overpressure at their upper tip toward a topographic load. Neutral buoyancy by itself cannot induce dikes to turn into sills, as previously suggested.

Description: Published

Description: 39-50

Description: 2V. Struttura e sistema di alimentazione dei vulcani

Description: JCR Journal

Description: The sources and sinks of stratospheric reactive nitrogen (NOy) in the Antarctic are known only qualitatively, because of the very few measurements of NOy available in this region. As a result, the effects of stratospheric NOy short- and long-term changes on the stratospheric concentration of ozone, water vapor, and other climate-forcing agents are still uncertain. To better understand the annual cycle of polar stratospheric NOy, we estimate its concentration in the Antarctic stratosphere during part of 1993 and throughout 1995. These estimates are obtained at seven potential temperature levels, extending from 18 to 30 km of altitude, and are associated with ground-based measurements of another tracer, N2O, in order to produce NOy-N2O correlation curves that can provide insights on nitrogen sources and sinks. To estimate NOy mixing ratios, we use ground-based and satellite measurements of major NOy constituents, connected by using air parcel trajectories and supplemented by model calculations of minor contributing species for which no suitable measurements exist. All the available NOy-N2O correlation points are averaged over three representative seasonal time periods in 1993 and six periods in 1995. Results show very similar correlation curves during the late summer and the fall of 1995, and again during the early spring 1993 compared with the early and late winter of 1995, although there are large seasonal changes due to transport and to condensation of NOy onto polar stratospheric clouds. We calculate a loss from the latter process of N = (6.3 ± 2.6) 107 kg of stratospheric nitrogen in the southern polar vortex during 1995.We also compare our correlation curves with those obtained in the Antarctic stratosphere during the Atmospheric Trace Molecule Spectroscopy mission ATMOS/ATLAS-3 in November 1994, finding important similarities but also critical differences that suggest that extravortex air is generally not an adequate representation of prewinter inner vortex conditions. Calculations of NOy winter removal in the Antarctic stratosphere which have used extra-vortex measurements as a surrogate for prewinter conditions may thus have underestimated true NOy removal. Our prewinter NOy estimates in the vortex core match values obtained by atmospheric models that incorporate upper atmospheric sources of NOy, supporting the belief that such sources have a significant effect on polar stratospheric NOy.

Description: Published

Description: 4428

Description: 5A. Ricerche polari e paleoclima

Description: JCR Journal

Description: We describe a new method for the reconstruction (or forecast) of probabilities that distal geographic locations were inundated by a giant pyroclastic density current (PDC) in terms of the flow mass and related uncertainties. Using appropriate model input uncertainty distributions, derived from expert judgements using the equal weights combination rule, we can estimate the mass amount needed to reach a particular distal locality at any given confidence level and compare this with ambiguous or inexact field data. Our analysis relies on different versions of the Huppert and Simpson (1980) integral formulation of axisymmetric gravity-driven particle currents. We focus on models which possess analytical solutions, enabling us to utilize a very fast functional approach for enumerating results and uncertainties. In particular, we adapt the ‘energy conoid’ approach to generate inundation maps along radial directions, based on comparison of the mass-dependent kinetic energy of the flow with the potential energy control by topography in the direction of flow at distal ranges. We focus on two different models: (i) Model 1 assumes the entire amount of solid material originates from a prescribed height above the volcano and flows as a granular current slowed down by constant friction; (ii) Model 2 is a multi-phase formulation and includes, in addition to suspended particles, interstitial gas thermally buoyant with respect to surrounding cold air. In the latter case, the flow stops propagating when the solid fraction becomes less than a critical value, and there is lift-off of the remaining mixture of gas and small particulates. Our model parameters can be further constrained where there is reliable field data or with information from analogue eruptions. Finally, we used a Bayes Belief Network related to each inversion model to evaluate probabilistically the uncertainties on the mass required, estimating correlation coefficients between the input variables and the calculated mass. For any major magnitude ignimbrite PDC scenario, our method provides a rational basis for assessing the probability of flow inundation at critical geographic locations within distal areas when there is major uncertainty about the actual or predicted extent of flow runout. Example case histories are illustrated.

Description: Published

Description: San Francisco (CA)

Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio

Description: In this study we present a new effort to improve the uncertainty quantification (UQ) of pyroclastic density current dynamics in the Campi Flegrei caldera, thanks to the implementation of a new 2D depth-averaged granular flow model in the Monte Carlo simulation of keycontrolling variables. Campi Flegrei caldera is an active and densely populated volcanic area in the urban neighborhood of Napoli, characterized by the presence of many dispersed cones and craters, and by a caldera wall more than one hundred meters high, towards East. Basic mapping of pyroclastic density currents (PDC) hazard at Campi Flegrei has been already reported in previous studies: some related to field reconstruction and numerical modeling of specific past eruptions or individual scenarios, while others endeavored to produce specific or integrated PDC hazard maps in which the variability of important parameters of the volcanic system was explicitly accounted for. In particular, [4, 2] obtained quantitative estimates of probabilistic PDC hazard, based on the implementation of a simplified kinematic invasion model able to represent main topographic effects. This model, called box model, was extensively run thousands of times in the Monte Carlo simulation varying vent location, eruptive scale, and time frequency of the future activity. In this study we build our effort upon the previous research started in [7, 5], and utilize the physical modeling approach of [6], with the effcient numerical solution of depth-averaged equations for the flow mass and momentum, considering the effects of basal and internal, velocity dependent, friction forces. The model describes the gas-particle mixture as a homogeneous flow, assuming a mechanism of particle deposition consistent with that previously implemented in the box model. UQ is performed by assuming three different components in the input space: (i) rheology parameters, (ii)volume scale, (iii) source location. Our statistical analysis focuses on the first two components, considering a relatively small number of source locations or an uncertain source location inside a subregion of the caldera. This is a first step before the exploration of the full spatial variability of the source location. The statistical inversion of box model equations, varying the vent location (x; y) and the value of inundated area A, can provide us with initial probability estimates for the volume scale of the PDC flow, either in terms of runout distance or volume extent of the multiphase mixture. Our depth averaged model relies on these estimates for setting up the volume scale of past flows. The calibration of rheology parameters is performed according to that. Thus, the rheology and volume components of the input space are conjointly explored by means of Latin Hypercube sampling, attempting a hierarchical conditioning on feasible inputs and plausible outputs [3]. [1] A. Bevilacqua, F. Flandoli, A. Neri, R. Isaia, S. Vitale, “Temporal models for the episodic volcanism of Campi Flegrei caldera (Italy) with uncertainty quantification," Journal of Geophysical Research: Solid Earth 121, 11 (2016). [2] A. Bevilacqua, A. Neri, M. Bisson, T. Esposti Ongaro, F. Flandoli, R. Isaia, M. Rosi, S. Vitale, “The e ects of vent location, event scale, and time forecasts on pyroclastic density current hazard maps at Campi Flegrei caldera (Italy)," Frontiers in Earth Science 5, 72 (2017). [3] A. Bevilacqua, A.K. Patra, M.I. Bursik, E.B. Pitman, J.L. Macías, R. Saucedo, D. Hyman, “Probabilistic forecasting of plausible debris flows from Nevado de Colima (Mexico) using data from the Atenquique debris flow, 1955," Natural Hazards Earth System Science 19, 791-820 (2019). [4] A. Neri, A. Bevilacqua, T. Esposti Ongaro, R. Isaia, W.P. Aspinall, M. Bisson, F. Flandoli et al., “Quantifying volcanic hazard at Campi Flegrei caldera (Italy) with uncertainty assessment: 2. Pyroclastic density current invasion maps," Journal of Geophysical Research: Solid Earth 120, 2330-2349 (2015). [5] T. Esposti Ongaro, S. Orsucci and F. Cornolti, “A fast, calibrated model for pyroclastic density currents kinematics and hazard," Journal of Volcanology and Geothermal Research 327, 257 - 272 (2016). [6] M. de’ Michieli Vitturi, T. Esposti Ongaro, G. Lari, and A. Aravena, “IMEXSfloW2D 1.0: a depth-averaged numerical flow model for pyroclastic avalanches," Geoscientific Model Development, 12, 581-595 (2019). [7] M. Todesco, A. Neri, T. Esposti Ongaro, P. Papale, and M. Rosi, “Pyroclastic flow dynamics and hazard in a caldera setting: Application to Phlegrean Fields (Italy)," Geochemistry Geophysics Geosystems, 7, Q11003 (2006).

Description: Published

Description: Pisa

Description: 5V. Processi eruttivi e post-eruttivi

Description: In December 2018, Mount Etna (Italy) experienced a period of increased eruptive activity that culminated in a fissure eruption on the southeast flank. After the onset of the flank eruption, the peak frequency of the summit infrasound signals decreased while resonance increased. We invert infrasound observations for crater geometry and show that crater depth and radius increased during the eruption, which suggests that the flank eruption drained magma from the summit and that eruptive activity led to erosion of the crater wall. By inverting the entire infrasound amplitude spectra rather than just the peak frequency, we are able to place additional constraints on the crater geometry and invert for, rather than assume, the crater shape. This work illustrates how harmonic infrasound observations can be used to obtain hightemporal‐ resolution information about crater geometry and can place constraints on complex processes occurring in the inaccessible crater region during eruptive activity.

Description: Published

Description: e2020GL088077

Description: 2V. Struttura e sistema di alimentazione dei vulcani

Description: JCR Journal

Description: This work focuses on how the progress in earthquake science that follows a large, deeply studied earthquake might be promptly combined with updated approaches of seismic hazard analysis to guide applicative choices for seismic risk reduction, such as postevent seismic microzoning and building design. Both seismic microzoning and seismic design of structures require strong motion records to perform numerical site response analyses. These records have to be related to the seismotectonic context and historical seismicity of the investigation area. We first performed a fault‐based probabilistic seismic hazard analysis in the area struck by the 2016 central Italy seismic sequence to individuate reference uniform hazard spectra at rock conditions. We used two different seismic hazard models, one considering 27 individual seismogenic sources (ISSs), and the second one involving grid point seismicity, using a fixed‐radius smoothing approach. The geological and seismotectonic data of the 2016 seismic sequence were used to update the model of ISSs. We performed a deaggregation analysis to evaluate the contribution of the ISS in the hazard of four representative sites and to select the magnitude‐distance pairs useful in the selection of the real accelerograms. The deaggregation analysis has been performed to identify which source and magnitude most contribute to the hazard for each site, and for different periods of spectral accelerations. Finally, we select, for each site, a set of natural accelerograms, from both nonimpulsive and pulse‐like records, based on the magnitude‐distance pairs that are compatible on average with target uniform hazard spectra.

Description: Published

Description: 595-620

Description: 6T. Studi di pericolosità sismica e da maremoto

Description: JCR Journal

Description: Recent findings on the nature of magnetic field fluctuations in the high-latitude ionospheric regions have suggested the existence of scaling features, which are the signature of the occurrence of turbulence. These features mainly characterize the magnetic field fluctuations in those regions where the field-aligned currents flow. Here, we investigate the nature of the Earth's magnetic field fluctuations using the high-resolution (50 Hz) magnetic measurements from the European Space Agency Earth's observation mission Swarm. Our study indicates that spatiotemporal anomalous scaling features characterize low-frequency magnetic field fluctuations in the high-latitude ionospheric regions of field-aligned currents at spatial scales in the range 0.8–80 km (timescales in the range 0.1–10 s). The signature of a multifractal nature of these fluctuations suggests a highly complex structure of the field-aligned currents. Our results support the view of inhomogeneous (filamentary) field-aligned currents, which can have relevant implications in the comprehension of the physical processes responsible for the magnetospheric-ionospheric coupling and ionospheric heating.

Description: ESA Contract No. 4000125663/18/I-NB (INTENS)

Description: Published

Description: e2019JA027429

Description: 1A. Geomagnetismo e Paleomagnetismo

Description: JCR Journal

Description: The purpose of this work is to study the subsoil structure of the Campi Flegrei area using both spectral ratios and array techniques applied to seismic noise. We have estimated the dispersion curves of Rayleigh waves by applying the Frequency–Wavenumber (f–k hereinafter) and Modified Spatial Autocorrelation (MSPAC) techniques to the seismic noise recorded by the underground short period seismic Array “ARF”, by the broadband stations of the UNREST experiment and by the broadband stations of the seismic monitoring network of INGV – Osservatorio Vesuviano. We have performed the inversion of a dispersion curve (obtained averaging the f–k and MSPAC dispersion curves of seismic noise and single phase velocity values of coherent transient signals) jointly with the H∕V spectral ratio of the broadband station CELG, to obtain a shear wave velocity model up to 2000 m depth. The best-fit model obtained is in a good agreement with the stratigraphic information available in the area coming from shallow boreholes and deep wells drilled for geothermal exploration. In active volcanic areas, such as Campi Flegrei, the definition of the velocity model is a crucial issue to characterize the physical parameters of the medium. Generally, a high quality characterization of the medium properties helps to separate the contributions of the volcanic source, path and site in the geophysical observables. Therefore, monitoring possible variations in time of such properties in general can help to recognize anomalies due to the volcano dynamics, i.e. fluid migration connected to the volcanic activity.

Description: Published

Description: 75–85

Description: 2V. Struttura e sistema di alimentazione dei vulcani

Description: JCR Journal

Description: Some physical processes due to Sun-Earth interaction can influence the configuration and the dynamics of the high-latitude ionospheric plasma, particularly during geomagnetically disturbed periods. A possible consequence of this interaction is the occurrence of turbulent fluctuations that can be observed both in magnetic and electric fields and plasma density. Here, we focus on the intermittent nature of high-latitude ionospheric electron density fluctuations during geomagnetically disturbed periods as observed by one of the satellites of the ESA-Swarm constellation. The most obvious finding emerging from this study is the strong intermittent character of electron density fluctuations and the existence of an agreement between the anomalous scaling features of electron density fluctuations and those expected from a passive scalar quantity in fluid turbulence. This latter result supports the view of a passive scalar behavior of electron density in the high-latitude ionosphere that can have significant implications in the field of SpaceWeather studies.

Description: financial support from European Space Agency (ESA contract N. 4000125663/18/I-NB-“EO Science for Society Permanently Open Call for Proposals EOEP-5 BLOCK4” (INTENS)) and from the Italian MIUR-PRIN grant 2017APKP7T on “Circumterrestrial Environment: Impact of Sun-Earth Interaction.”

Description: Published

Description: e2020GL089628

Description: 1A. Geomagnetismo e Paleomagnetismo

Description: JCR Journal

Description: This work has been partially supported by the project V1 “Stima della pericolosità vulcanica in termini probabilistici” funded by Dipartimento della Protezione Civile (Italy).

Description: Published

Description: 5V. Processi eruttivi e post-eruttivi

Description: This paper detects the presence of seasonality, stationarity, and long-range memory structures in daily radon measurements in a permanent monitoring station in central Italy. The transient dynamics and the seasonality structure are identified by power spectral analysis based on the continuous wavelet transformation and a clear 1-year periodicity emerges. The stationarity in the data is assessed with the Dickey-Fuller test; the decay of the estimated autocorrelation function and the estimated Hurst exponent indicate the presence of long-range dependence. All the main characteristics of the data have been properly included in a modelling structure. In particular, an autoregressive fractionally integrated moving average (ARFIMA) model is estimated and compared with the classical ARMA and ARIMA models in terms of goodness of fit and, secondarily, of forecast evaluation. An autoregressive model with a non-integer value of the differencing parameter ($d=0.278$) resulted to be the most appropriate on the basis of Akaike Information Criterion, the diagnostic on the residuals, and the Root Mean Squared Error. The results suggest that there is statistically-significant evidence for not rejecting the presence of long memory in the radon concentration. The radon measurements are better characterised as being stationary, but with long memory and so the statistical dependence decays more slowly than an exponential decay.

Description: Published

Description: id 575001

Description: 7T. Variazioni delle caratteristiche crostali e precursori sismici

Description: JCR Journal

Description: The high potential of probabilistic approaches for hazard assessment was identified by the VIMESEA group during the first meeting. In this context the INGV group has developed a novel approach that was first applied to the Phlegrean fields in Italy. This presentation was aimed to present further application to other volcanic areas in the world to address probabilities of volcanic vent reactivation. Though the message delivered by such simulations to civil authorities in charge of volcanic crisis management may not be straightforward, the VIMESEA participants concluded that the probabilistic approaches are essential for hazard assessment.

Description: Published

Description: Clermont-Ferrand (France)

Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio

Description: The partitioning of REE,Y and Sc (R3+) between olivine and melt has been investigated experimentally during basalt-carbonate interaction. Three synthetic basalts (meltMg#72, meltMg#75 and meltMg#78) were doped with 0, 10 and 20 wt% CaCO3 and then equilibrated for 72 h at 1 atm, 1,150, 1,200 and 1,250 °C, and the QFM oxygen buffer. The thermal decomposition of CaCO3 produced CaO contents in the melt up to ~22 wt%. Regular relationships are found between the ionic radius and the partition coefficient (DR3+), showing typical near-parabolic patterns. DR3+ is weakly dependent on temperature, but decreases with increasing CaCO3 in the starting material (e.g., DSc decreases from 0.20 to 0.13). From the point of view of the lattice strain theory, DR3+ is described in terms of the radius of the crystal site (r0), the Young Modulus (E) due to the elastic response of that site to lattice strain caused by cation insertion, and the strain-free partition coefficient (D03+). The value of r0 decreases as Ca cations are accommodated into the more distorted M2 site of olivine via progressive CaFe substitutions. This mechanism is accompanied by a higher proportion of Mg cations entering into the smaller M1 site, making the optimum ionic radius smaller and favoring the crystallization of more forsteritic olivines from decarbonated melts. The enrichment of Ca in the crystal lattice is also proportional to the number of Si and Ca cations available in the melt. This causes E to be anticorrelated either with Ca in olivine or the activity of CaO in the melt. R3+ cations behave as network modifiers and, during basalt-carbonate interaction, the increasing abundance of non-bridging oxygens enhances the solubility of REE, Y and Sc in the melt. As a consequence, D03+ is negatively correlated with the degree of melt depolymerization. Additionally, the strain of the crystal lattice dominates the DR3+ parabolic patterns and D03+ is strongly controlled by forsterite and aluminium concentrations in olivine. The accommodation of REE, Y and Sc in the crystal lattice requires maintenance of local charge-balance by the generation of vacancies, in accord with a paired substitution of R3+ and a vacancy for Mg in octahedral sites.

Description: Published

Description: 327-340

Description: 3V. Proprietà chimico-fisiche dei magmi e dei prodotti vulcanici

Description: JCR Journal

Description: Public concern about anthropogenic seismic- ity in Italy first arose in the aftermath of the deadly M ≈ 6 earthquakes that hit the Emilia-Romagna region (northern Italy) in May 2012. As these events occurred in a (tectonically active) region of oil and gas production and storage, the question was raised, whether stress perturbations due to underground industrial activities could have induced or triggered the shocks. Following expert recommendations, in 2014, the Italian Oil & Gas Safety Authority (DGS-UNMIG, Ministry of Economic Development) published guidelines (ILG - Indirizzi e linee guida per il monitoraggio della sismicità, delle deformazioni del suolo e delle pressioni di poro nell’ambito delle attività antropiche), describing regula- tions regarding hydrocarbon extraction, waste-water in- jection and gas storage that could also be adapted to other technologies, such as dams, geothermal systems, CO2 storage, and mining. The ILG describe the frame- work for the different actors involved in monitoring activities, their relationship and responsibilities, the procedure to be followed in case of variations of mon- itored parameters, the need for in-depth scientific anal- yses, the definition of different alert levels, their mean- ing and the parameters to be used to activate such alerts. Four alert levels are defined, the transition among which follows a decision to be taken jointly by relevant au- thorities and industrial operator on the basis of evalua- tion of several monitored parameters (micro-seismicity, ground deformation, pore pressure) carried on by a scientific-technical agency. Only in the case of liquid reinjection, the alert levels are automatically activated on the basis of exceedance of thresholds for earthquake magnitude and ground shaking – in what is generally known as a Traffic Light System (TLS). Istituto Nazionale di Geofisica e Vulcanologia has been charged by the Italian oil and gas safety authority (DGS- UNMIG) to apply the ILG in three test cases (two oil extraction and one gas storage plants). The ILG indeed represent a very important and positive innovation, as they constitute official guidelines to coherently regulate monitoring activity on a national scale. While pilot studies are still mostly under way, we may point out merits of the whole framework, and a few possible critical issues, requiring special care in the implementa- tion. Attention areas of adjacent reservoirs, possibly licenced to different operators, may overlap, hence mak- ing the point for joint monitoring, also in view of the possible interaction between stress changes related to the different reservoirs. The prescribed initial blank- level monitoring stage, aimed at assessing background seismicity, may lose significance in case of nearby ac- tive production. Magnitude – a critical parameter used to define a possible step-up in activation levels – has inherent uncertainty and can be evaluated using differ- ent scales. A final comment considers the fact that relevance of TLS, most frequently used in hydraulic fracturing operations, may not be high in case of trig- gered tectonic events.

Description: Published

Description: 1015–1028

Description: 1IT. Reti di monitoraggio e sorveglianza

Description: JCR Journal

Description: Earthquake hypocentral location is perhaps the most classical problem in seismology, the solution of which is often affected by significant uncertainty. In monitoring the effects of underground anthropogenic activities, the earthquake hypocentral location, magnitude, and ground motions are important parameters for managing induced seismicity (as e.g., for operating traffic‐light systems). Such decisional systems define the operative reactions to be enacted once an earthquake, exceeding some magnitude or ground‐motion threshold, occurs within a monitoring volume defined in the neighborhood of a certain anthropogenic underground activity. In this case, a reliable evaluation of the hypocentral location, along with its uncertainty, becomes crucial for rational decision making. In this article, we analyze different sources of uncertainty that can be relevant for the determination of earthquake source locations, and introduce a logic‐tree‐based ensemble modeling approach for framing the problem in a decision‐making context. To demonstrate the performance of the proposed approach, we analyze uncertainties in the location of a seismic event that occurred on 22 July 2019 within the perimeter of the monitoring domain defined in the Val d’Agri oil field (southern Italy). We cast the result as a model ensemble that allows us to obtain samples from a parent distribution that better represents both aleatory and epistemic uncertainties of the earthquake location problem. We find that often‐neglected epistemic uncertainties (i.e., those that arise when considering alternative plausible modeling approaches or data) can be considerably larger and more representative of the state of knowledge about the source location, than the standard errors usually reported by the most common algorithms. Given the consequential repercussions of decision making under uncertainty, we stress that an objective evaluation of epistemic uncertainties associated with any parameter used to support decisional processes must be a priority for the scientific community.

Description: Centro per il Monitoraggio delle attività di Sottosuolo (CMS).

Description: Published

Description: 2423–2440

Description: 3SR TERREMOTI - Attività dei Centri

Description: JCR Journal

Description: Campi Flegrei (CF) is an active, densely populated, caldera with very high risks associated with the occurrence of pyroclastic density currents (PDCs). Mapping of PDCs hazard in caldera settings is challenging due to the large uncertainty on future eruption scale and vent location as well as the complex dynamics of flows over caldera topography. First background probability maps of PDC invasion were produced adopting a vent-opening probability map, with associated uncertainty, of the whole caldera based on the eruptive record of the last 15 kyr. Maps were produced by a Monte Carlo approach by using a simplified inundation model based on the “box model” approximation tuned to results from 2D transient numerical simulations of flow dynamics. In this presentation we illustrate the independent effects of event scale and vent location, as well as of possible correlations between them, on the resulting invasion maps. The analysis allowed to identify areas with elevated probabilities of flow invasion as a function of the diverse assumptions made. With quantification of some sources of uncertainty in relation to the system, we were able also to provide mean and percentile maps of PDC hazard levels.

Description: Published

Description: Prague (CZ)

Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio

Description: After the large scale event of Neapolitan Yellow Tuff (~15 ka BP), intense and mostly explosive volcanism has occurred within and along the boundaries of the Campi Flegrei caldera (Italy). Eruptions occurred closely spaced in time, over periods from a few centuries to a few millennia, and were alternated by periods of quiescence lasting up to several millennia. Often events also occurred closely in space thus generating a cluster of events. The most recent eruption was that of Monte Nuovo in AD 1538. There is a remarkable uncertainty on the eruptive record, affecting the time of eruptions, location of vents as well as the erupted volume estimates. This study had two main objectives: 1) to describe the record uncertainty by using a quantitative model and 2) to develop, based on the uncertainty assessment, a temporal probability model to describe the temporal and spatial eruptive behaviour of the caldera. In particular, the study adopts a time-space double stochastic non-homogeneous Poisson-type model with a local self-exciting feature able to generate clustering of events which are consistent with the reconstructed record of Campi Flegrei. Results allow to evaluate similarities and differences between the three epochs of activity as well as to derive eruptive base-rate of the caldera and its capacity to generate clusters of events. The temporal probability model is also used to investigate the effect of Monte Nuovo event on a possible reactivation of the caldera and to estimate the time to the next eruption under different volcanological and modelling assumptions.

Description: Published

Description: Roma

Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio

Description: Lagrangian particle dispersal models are commonly used for tracking ash particles emitted from volcanic plumes and transported under the action of atmospheric wind fields. In this work, we adopted a Lagrangian particle model to carry out an uncertainty quantification analysis of volcanic ash dispersal in the atmosphere focused on the uncertainties affecting particle source conditions. To this aim the Eulerian fully compressible mesoscale non-hydrostatic model WRF was used to generate the driving wind field. The Lagrangian particle model LPAC (de’Michieli Vitturi et al., JGR 2010) was then used to simulate the transport of mass particles under the action of atmospheric conditions. The particle motion equations were derived by expressing the Lagrangian particle acceleration as the sum of the forces acting along its trajectory, with drag forces calculated as a function of particle diameter, density, shape and Reynolds number. The simulations were representative of weak plume events of Mt. Etna and aimed to quantify the effect on the dispersal process of the uncertainty in the mean and variance of a Gaussian density function describing the grain-size distribution of the mixture and in the particle sphericity. In order to analyze the sensitivity of particle dispersal to these uncertain parameters with a reasonable number of simulations, and therefore with affordable computational costs, response surfaces in the parameter space were built by using the generalized polynomial chaos technique. The uncertainty analysis allowed to quantify the most probable values, as well as their pdf, of the number of particles as well as of the mean and variance of the grain size distribution at various distances from the source, both in air and on the ground. In particular, results highlighted the strong reduction of the uncertainty ranges of the mean and variance of the grain-size distribution with increasing distance from source and the significant control of particle sphericity on the dispersal process.

Description: Published

Description: San Francisco (CA)

Description: 5V. Processi eruttivi e post-eruttivi

Description: Pyroclastic density currents (PDCs) represent one of the most dangerous volcanic hazards for people living in proximity of explosive volcanoes. The zonation of areas potentially affected by this threat is therefore of paramount importance and is the first step needed to set up appropriate mitigation measures. Campi Flegrei (CF) caldera represents a high-risk volcano with a remarkable PDC hazard due to the frequent occurrence of this phenomenon in its eruptive history. Despite the fact that CF caldera has been the object of many studies in recent decades, the mapping of PDC hazard there remains particularly challenging due to the remarkable variability of potential vent locations and eruption scales, and the complex dynamics of PDC propagation over the caldera topography. In this study we have produced, through the application of a doubly stochastic model, quantitative background (also called long-term or baseline) probabilistic maps of PDC invasion able to incorporate some of the main sources of epistemic uncertainty that influence the models for aleatoric (physical) variability. The new method developed combines the spatial probability distribution of vent opening locations, the density distribution of PDC invasion areas, and a simplified PDC model able to describe the main effect of topography on flow propagation. Our results indicate that the entire caldera has the potential to be affected (with a mean probability of flow invasion higher than about 5%) and the central-eastern area of the caldera (i.e. Agnano-Astroni-Solfatara) has invasion probabilities above about 30% (with local peaks of mean probability of about 50% in Agnano). Significant mean probabilities (up to values of about 10%) are also computed in some areas outside the caldera borders. Our findings are quite robust against different assumptions about several of the main physical and numerical parameters adopted in the study. In addition to mean values of probability of PDC invasion, the study provides the estimates of the credible uncertainty ranges associated with such probabilities in relation to some key sources of epistemic uncertainty. From our analysis, uncertainty spreads on invasion probabilities inside the caldera typically range between ±15 and ±35% of the local mean value, with an average of about ±25%; wider uncertainties are found outside the caldera, with an average above ±50% and a significantly larger range of variability from place to place.

Description: Published

Description: Napoli

Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio

Description: This work presents the first chemical and isotopic (δ13C-CO2, δ13C-CH4, 3He, 4He, 20Ne, 40Ar, 36Ar, δ18O, and δD) data for fluid discharges fromGuallatiri volcano, a remote and massive stratovolcano, which is considered as the second most active volcano of the Central Volcanic Zone (CVZ) in northern Chile. Fumarolic gases had outlet temperatures of between 80.2 and 265 °C, and showed a significant magmatic fluid contribution marked by the occurrence of SO2, HCl, and HF that are partially scrubbed by a hydrothermal aquifer. The helium isotope ratios (〈 3.2) were relatively low compared to those of other active volcanoes in CVZ, possibly due to contamination of the magmatic source by 4He-rich crust and/or crustal fluid addition to the hydrothermal reservoir. Geothermometry in the H2O-CO2-CO-H2-CH4 system suggests equilibrium temperatures of up to 320 °C attained in a vapor phase at redox conditions intermediate between those typical of hydrothermal and magmatic environments. Thermal springs located 12 km northwest of the volcano’s summit had outlet temperatures of up to 50.1 °C, neutral to slightly basic pH, and a sodium bicarbonate composition, typical of distal fluid discharges in volcanic systems. Cold springs at the base of the volcanic edifice, showing a calcium sulfate composition, were likely produced by interaction of shallow meteoric water with CO2- andH2S-rich gases. A geochemical conceptual model was constructed to graphically represent these results, which can be used as an indication for future geochemical monitoring and volcanic hazard assessment.

Description: Published

Description: id 57

Description: 2V. Struttura e sistema di alimentazione dei vulcani

Description: 4V. Processi pre-eruttivi

Description: JCR Journal

Description: Campi Flegrei is an example of active and densely populated caldera with a very high volcanic risk associated with the occurrence of Pyroclastic Density Currents (PDCs) produced by explosive events of variable scale and vent location. The mapping of PDC hazard in such caldera setting is particularly challenging due to the complex dynamics of the flow, the large uncertainty of future vent location and the complex topography affecting the flow propagation. Nevertheless, probabilistic mapping of PDC invasion, able to account for the intrinsic uncertainties affecting the system, is needed for hazard assessment. In this study, we show the results of new field work and statistical analysis of past eruptive activity aimed at producing long-term probabilistic maps of vent opening at Campi Flegrei. The field work was focused on the structural and morphological nature of the caldera and particularly on the reconstruction of the location of past eruptive vents as well as of main faults and fissures formed in the last 15 kyrs of activity. One objective of the analysis was to incorporate into the vent opening maps the main uncertainties affecting the system. This was done by adopting appropriate density distributions of the probability of vent opening of the different areas of the caldera and by relying on expert judgement. Then, we used these maps to produce a variety of probabilistic PDC hazard maps of the Campi Flegrei area based on different invasion models and accounting for the uncertainty in vent opening and event size. Invasion models were based on simple correlations derived from field reconstruction of past events, one-dimensional models based on a linear decay of the flow energy (e.g. energy line), and simple energy decay models tuned on transient and 2D numerical simulations of the flow dynamics.

Description: Unpublished

Description: Pisa

Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio

Description: A research approach that integrated different geophysical methods for archaeological prospection was carried out to understand the nature and chronological development of the curvilinear structure in the archaeological site of “Villa degli Antonini” (Genzano di Roma, Italy) (hereafter VA), and the finding of the settlement structure in the archaeological site of Rota Ria (Mugnano in Teverina, Viterbo, Italy) (hereafter RR) (SKRAME et al., 2016). To this purpose a detailed magnetic prospecting survey was carried out since the walls of the curvilinear structure are made of volcanic rocks, such as lava and tuffs of local provenience, that induce a very high degree of magnetization. Even in the RR archaeological framework, both the geological environment and the buried walls made of peperino and tuff blocks, suggested the use of magnetic prospecting survey. In order to determine the exact shape and therefore the best excavation strategy for these buried archaeological structures, a series of different geophysical investigations (Electromagnetic (EMI) and Ground penetrating radar survey (GPR)) were carried out. The final step of the investigation was the excavation in the targeted sector of the study areas in order to test the validity of the geophysical interpretations. The most interesting result was that, in both cases, the excavations have confirmed the results obtained during the magnetic surveying.

Description: AGH University of Science and Technology

Description: Published

Description: Kraków, Poland

Description: 7A. Geofisica per il monitoraggio ambientale

Description: 7SR AMBIENTE – Servizi e ricerca per la società

Description: Mapping of pyroclastic density currents (PDCs) hazard in caldera settings is particularly challenging due to the large uncertainty on future vent location and eruption scale as well as the complex dynamics of the flow over the irregular caldera topography. Nevertheless, probabilistic mapping of PDC invasion, able to account for the intrinsic uncertainties affecting the system, is needed for hazard assessment, particularly for highly populated regions. Campi Flegrei (CF) is a vivid example of active and densely populated caldera with a very high risk associated with the occurrence of PDCs produced by explosive events. In this presentation we show the results of new field work and mathematical modelling of past eruptive activity aimed at producing long-term probabilistic vent opening and PDC invasion maps at CF. Field work was focused on the structural and morphological features of the caldera and particularly on the reconstruction of the location of past eruptive vents as well as of the distribution of the main faults and fractures formed in the last 15 kyr of activity. One specific objective of the analysis was to incorporate into the vent opening maps the main uncertainties affecting the system by adopting appropriate density distributions and by relying on expert judgement. We then used these maps to produce, by adopting a Monte Carlo approach, a variety of probabilistic PDC hazard maps of the CF area based on different invasion models and accounting for the uncertainty on vent location and event scale. In particular we developed and adopted a simplified invasion flow model based on the so-called box model approximation and tuned on transient and 2D numerical simulations of the flow dynamics. The new model allowed to describe the exponential decay of the flow energy as well as to account for first-order topographic effects. The developed methodology appears able to provide relatively quick and robust probabilistic assessments of PDC hazard in caldera settings and could be potentially extended to other calderas worldwide.

Description: Published

Description: San Francisco (CA)

Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio

Description: The Somma-Vesuvius (SV) volcanic complex has shown in his history a moderate variability of eruptive styles associated with a significant spatial variability of the associated vent locations. This is proved by the presence of numerous eccentric vents which fed effusive eruptions and also by the variability of the vent area of the large explosive eruptions that showed a shift within the present multistage SV caldera. Numerical simulations of explosive eruptions with variable vent locations inside the caldera have shown that this variability, although restricted to an area a few square kilometers, can have a major effect on the associated hazard, particularly for the threat associated to the occurrence of pyroclastic density currents produced by column collapse. This work summarizes some of the activities that have been put forward with the aim of producing a first long-term vent opening probability map for the area of the Somma-Vesuvius caldera. These activities mainly consist in the recognition and collection of key volcano features that can be linked to the spatial distribution of volcanic activity as well as used for their probabilistic treatment. Key variables that have been considered so far include: a) location of Plinian and sub-Plinian volcanic vents; b) location of moderately explosive eruptions (Violent Strombolian to ash emission); c) location of parasitic vents and eruptive fissures; d) distribution of subsurface faults from DTM analysis; e) distribution of the main deep lineaments, as deduced from published geophysical inversions. Locations of Plinian and sub-Plinian volcanic vents have been represented considering their uncertainties based on the available reconstruction of deposits and expert judgment. Parasitic cone and eruptive fissure locations have been also compiled after a comparative analysis of different bibliographic sources, including geological, geomorphological and topographic maps. Distribution of faults and fractures have been finally derived by integrating data from literature studies and new analysis of different digital terrain models (DTM). All the data have been imported into a GIS-based workspace that allowed to organize, analyze and elaborate different datasets. By assuming that each dataset can contribute to the probability distribution of vent opening through the assignment of appropriate weights (e.g. based on expert elicitation), preliminary vent opening (susceptibility) maps will be produced. Results will be used in the production of more accurate hazard maps of the range of expected explosive phenomena in case of a future reactivation of Somma-Vesuvius.

Description: Published

Description: Milano

Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio

Description: A long-term gravity and elevation changes time series (2001-2006) at the restless caldera of Nisyros in Greece is here reported. After a period of intense seismic activity (1995-1998), associated with an increase of fumarolic activity and ground deformation of Nisyros volcano which no any eruption occurred, and then a gravity network was settled in June 2001 and re-occupied annually up to 2004 and in June 2006. Discrete gravity measurements have been carried out at located benchmarks surrounding Nisyros island in proximity to hydrotermal area within the caldera floor and taking into account the effect of the vertical ground movements in order to quantify gravity changes of the volcano. A general positive observed gravity change was determined at all stations of the network inside caldera rim. In the same time, a temporal and spatial evolution of the gravity changes was found between 2001 and 2004: it was observed a steady-rise in gravity variations between 2001-2003, obtaining maximum positive gravity variations up to +60 Gal confined in the caldera floor area at the base of the presently active crater, where the most fumarolic activity is concentrated; in contrast a spatial distribution of gravity changes is recorded during 2003-2004 and the maximum positive gravity variations are confined in the caldera rim near Nikia village. In this way residual gravity changes were obtained and applications of Gausss theorem to the study of the excess mass recorded during 2001-2006 is explored. During recent unrest period magma replenishment genereted a great quantity of steam hot hydrothermal fluids which is released towards the surface underneath the southeastern part of the caldera floor. The gravity changes might be attributed to the migration of fluids probably occurring through pre-existing faults.

Description: Published

Description: Perugia (Italy), 2-13 July 2007

Description: 2V. Struttura e sistema di alimentazione dei vulcani

Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio

Description: 6SR VULCANI – Servizi e ricerca per la società

Description: Overview on my scientific research in probability and volcanology Andrea Bevilacqua Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Pisa. Postdoctoral Researcher in: “Development and application of physical-mathematical and statistical models in quantifying volcanic hazard”

Description: Published

Description: Pisa

Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio

Description: The study of volcanic mass flow hazards in a probabilistic framework centers around systematic experimental numerical modelling of the hazardous phenomenon and the subsequent generation and interpretation of a probabilistic hazard map (PHM). For a given volcanic mass flow phenomenon (e.g., lava flow, lahar, pyroclastic flow, etc.), the PHM is typically interpreted as giving the point-wise probability of flow material inundating a given location. By formalizing the generation and properties of the PHM, we show that a PHM may be used to generate additional statistical measures of the hazard, which have been unrecognized in probabilistic hazard analysis, and may be of interest to analysts, planners, emergency managers, and exposed populations. Our formalism shows that a typical PHM not only gives the inundation probability at every location, but also represents a type of cumulative distribution function for the location of the inundation boundary with a corresponding probability density function. This distribution runs over contours of steepest gradient ascent on the PHM. Consequently, 2D curves can be constructed which represent the mean, median and modal locations of the inundation edge. Additionally, methods of calculation for the standard deviation and confidence intervals are presented that take the form of regions of the map surrounding the mean and median edge locations, respectively. These additional measures of central tendency and variance add significant value to probabilistic hazard analyses, giving a richer statistical description of the probability distributions underlying PHMs. The theory may be used to construct improved hazard maps, which could prove useful for planning and emergency management purposes. Additionally, these methods can help evaluate common problems that arise in numerical models of geophysical mass flows, such as artificially thin and fast-propagating flow boundaries. The formalism also allows for application to processes describable by analytic solutions. The connection between the PHM, its derived measures, and the underlying parameter variation is explicit, allowing for better parameter estimation from natural data for use in flow modeling.

Description: Published

Description: Washington DC

Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio

Description: I MODULO Complessità e Probabilità Angelo Vulpiani – Università di Roma “La Sapienza”, 17 e 18 gennaio 2019 Franco Flandoli – Scuola Normale Superiore, 25 gennaio 2019 con Laboratorio a cura di Andrea Bevilacqua - Istituto Nazionale di Geofisica e Vulcanologia (sezione di Pisa) 3 lezioni di 2 ore ciascuna Se osserviamo il mondo che ci circonda notiamo che esistono fenomeni regolari e prevedibili, ad esempio il susseguirsi del giorno e della notte, l'alternanza delle stagioni e le eclissi che sono calcolate dagli astronomi con grande anticipo e precisione. Per descrivere queste situazioni si usano leggi deterministiche, il cui prototipo sono le equazioni differenziali alla base della meccanica di Newton e di gran parte della fisica classica. Ci sono però anche fenomeni che non sembrano affatto seguire leggi precise come quelle che valgono per le eclissi o per i corpi che cadono. Quando abbiamo a che fare con giochi come i dadi, la roulette, il lotto, l'andamento della borsa, e così via, invece parlare di leggi usiamo termini come caso e aleatorietà, e la descrizione matematica si basa sulla teoria della probabilità. Ovviamente non è del tutto soddisfacente assumere che esistano due tipi di situazioni completamente diverse: quelle regolate da leggi certe (deterministiche), e quelle che seguono leggi aleatorie. Si potrebbe infatti notare che i dadi e le palline delle roulette obbediscono alle leggi della meccanica di Newton, proprio come i sassi che cadono e i corpi celesti. È possibile superare questa dicotomia apparentemente inconciliabile? Vedremo come in presenza di caos, in cui piccole differenze dello stato del sistema al tempo iniziale vengono amplificate in modo esponenziale (il famoso, e spesso citato a sproposito, effetto farfalla), è possibile introdurre in modo coerente (e non soggettivo) concetti probabilistici anche in sistemi deterministici. È interessante notare che, per quanto riguarda la certezza, questa non è affatto esclusiva delle teorie deterministiche. I teoremi limite (primo fra tutti la legge dei grandi numeri) mostrano che in un sistema con un grande numero di componenti si può avere un determinismo probabilistico. Questo è stato ben riassunto da B.V. Gnedenko e A.N. Kolmogorov: «Tutto il valore epistemologico della teoria delle probabilità è basato su questo: i fenomeni aleatori, considerati nella loro azione collettiva a grande scala, generano una regolarità non aleatoria».

Description: Published

Description: Pisa

Description: 1TM. Formazione

Description: Recent volcanic gas compilations have urged the need to expand in-situ plume measurements to poorly studied, remote volcanic regions. Despite being recognized as one of the main volcanic epicenters on the planet, the Vanuatu arc remains poorly characterized for its subaerial emissions and their chemical imprints. Here, we report on the first plume chemistry data for Mount Garet, on the island of Gaua, one of the few persistent volatile emitters along the Vanuatu arc. Data were collected with a multi-component gas analyzer system (multi-GAS) during a field campaign in December 2018. The average volcanic gas chemistry is characterized by mean molar CO2/SO2, H2O/SO2, H2S/SO2 and H2/SO2 ratios of 0.87, 47.2, 0.13 and 0.01, respectively. Molar proportions in the gas plume are estimated at 95.9 11.6, 1.8 0.5, 2.0 0.01, 0.26 0.02 and 0.06 0.01, for H2O, CO2, SO2, H2S and H2. Using the satellite-based 10-year (2005–2015) averaged SO2 flux of ~434 t d􀀀1 for Mt. Garet, we estimate a total volatile output of about 6482 t d􀀀1 (CO2 ~259 t d􀀀1; H2O ~5758 t d􀀀1; H2S ~30 t d􀀀1; H2 ~0.5 t d􀀀1). This may be representative of a quiescent, yet persistent degassing period at Mt. Garet; whilst, as indicated by SO2 flux reports for the 2009–2010 unrest, emissions can be much higher during eruptive episodes. Our estimated emission rates and gas composition for Mount Garet provide insightful information on volcanic gas signatures in the northernmost part of the Vanuatu Arc Segment. The apparent CO2-poor signature of high-temperature plume degassing at Mount Garet raises questions on the nature of sediments being subducted in this region of the arc and the possible role of the slab as the source of subaerial CO2. In order to better address the dynamics of along-arc volatile recycling, more volcanic gas surveys are needed focusing on northern Vanuatu volcanoes.

Description: This research was conducted as part of the Trail by Fire II—Closing the Ring Project (PI: Y. Moussallam) funded by the National Geographic Society (grant number CP-122R-17), the Rolex Awards for Enterprise and the French national Research Institute for Development (IRD). J.L. also acknowledges travel funding support from Ministero dell’istruzione, dell’università e della ricerca (MIUR;) under grant n. PRIN2017-2017LMNLAW).

Description: Published

Description: id 7293

Description: 4V. Processi pre-eruttivi

Description: JCR Journal

Description: Earthquake forecasting and seismic hazard analysis: some insights on the testing phase and the modeling

Description: Alma Mater Studiorum – Università di Bologna

Description: Unpublished

Description: 6T. Studi di pericolosità sismica e da maremoto

Description: Scopo di questo lavoro è lo studio di una depressione morfologica presente in località Laghetto (Roma) che ha subito una notevole antropizzazione negli ultimi venti anni.

Description: Published

Description: Roma 18-20 novembre 2003

Description: 7A. Geofisica per il monitoraggio ambientale

Description: 7SR AMBIENTE – Servizi e ricerca per la società

Description: La tesi inizia con un capitolo dedicato al caso in dimensione 1: dopo la definizione di misura di occupazione, si ottiene la formula di Tanaka che definisce il tempo locale, partendo dalla formula di Ito. Segue un'altra costruzione, classica, del tempo locale, che usa risultati di analisi funzionale; poi si danno la caratterizzazione di Levy del tempo locale e gli importanti risultati di continuità. Sono poi esposte delle importanti applicazioni del tempo locale. Nel capitolo successivo si tratta il caso in dimensione maggiore di 1: viene esposta una dimostrazione elementare della trascurabilità secondo Lebsgue delle traiettorie di un BMd, d 〉 1, e di conseguenza della singolarità della relativa misura di occupazione. Poi sono enunciati alcuni risultati noti che sfruttano le proprietà della misura di occupazione per ottenere l'unicità forte nelle SDE, grazie al teorema di Davie. Nella seconda parte della tesi per prima cosa viene costruito il nuovo tempo locale ripetto alle sottovarietà d 〉 1 dimensionali. Inizialmente si affrontano i casi semplici di iperpiani, o curve nel piano, per poi esporre il caso generale delle sottovarietà e persino insiemi ancor meno regolari. Infine, nell'ultimo capitolo si arriva alla costruzione della formula di disintegrazione della misura di occupazione rispetto a foliazioni differenziabili, limitandosi per semplicità alla misura di occupazione di un BM bidimensionale. Si dà un esempio di integrazione tramite questa formula, e poi si dimostra che i supporti delle misure sono insiemi perfetti a parte interna vuota.

Description: Università di Pisa

Description: Published

Description: 3IT. Calcolo scientifico

Description: This thesis was developed and supported thanks to the agreement between Istituto Nazionale di Geofisica e Vulcanologia and Scuola Normale Superiore di Pisa (Convenzione INGV-SNS 2009-2011). The thesis has been partially developed in the framework of the project ‘V1 - Stima della pericolosità vulcanica in termini probabilistici’ funded by Dipartimento della Protezione Civile. Partial support was also provided by the EU-funded project ‘MEDSUV - Mediterranean Supervolcanoes’ (grant 308665) and the COST Action ‘EJN - Expert Judgement Network: bridging the gap between scientific uncertainty and evidence-based decision making’ (IS1304).

Description: Scuola Normale Superiore di Pisa

Description: Published

Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio

Description: The ancient city of Elaiussa Sebaste (Ayash, Turkey) is located on the south-eastern coast of Asia Minor (the old district of Cilicia Tracheia). The pottery circulation in this area, as well as the local productions, is quite unknown. A preliminary study on the various ceramics coming from the excavations at Elaiussa Sebaste, provides an interesting view on the Late- Roman and Byzantine ceramics trade in the Eastern Mediterranean. On the basis of sixth and seventh century archaeological contexts, it can say that Elaiussa was a Late Roman 1 (LR1) amphorae and coarse wares production centre. On the basis of archaeological classification which describes different classes of using and their possible provenance, with the following mineralogical and petrography studies, it is possible to confirm partly archaeological data. The study of thin section of ceramic sample shows hiatal and serial distribution of grain sizes. It is evident that the large fragments in hiatal distribution pattern were not present in the clay from the beginning, but were added to it during the processing phase. The chemical composition of pottery can be used to distinguish products of different origin. The chemical composition of the sherds is determined using wavelengthdispersive X-ray fluorescence spectrometry. Depending on the available amount of powdered sample, all major chemical elements and some minor elements (Zn, Cu, Ni, Co, Ce, Ba, La, Cr, V, Th, Pb, Ga, Rb, Sr, Y, Zr, Nb) were analysed thus yielding sufficient information to distinguish groups. The XRF data seem to identify that most LR1 samples used similar or even the same source(s) of clay (homogeneity of XRF data), but are nevertheless probably separate fabrics. This section studies were applied to control the resulting chemical grouping and to find traces of the geological background of the manufacturing area. The variation in potassium and sodium contents is larger than it would be expected if any of this pottery were made from one clay. From the typically high Mg, Cr and Ni contents and from typical inclusions of serpentine and pyroxenes which can be seen in microscopical study of the paste, clay used has a probable origin from ophiolithic rocks. It will be compared to the ophiolithic rocks, a possible provenance of the raw materials from ophiolitic belt which goes from the Taurus to the Mediterranean coast near Antiochus, with the inclusions of pyroxene and serpentine as typical inclusions in LR1. The high calcium contents show larger variation between 27,67 and 19,06 % of CaO; using calcareous clays was common in the pottery tradition of the Mediterranean and the Near East except for some cooking pot wares. Corresponding author:

Description: ISBN:84-00-08421-7

Description: Unpublished

Description: Madrid, Spain, 21-24 June 2006

Description: 7SR AMBIENTE – Servizi e ricerca per la società

Description: The equilibrium composition of volcanic gaseswith their magma is often overprinted by interaction with ashallow hydrothermal system. Identifying the magmatic sig-nature of volcanic gases is critical to relate their composi-tion to properties of the magma (temperature,fO2, gas-meltsegregation depth). We report measurements of the chemi-cal composition and flux of the major gas species emittedfrom Turrialba Volcano during March 2013. Measurementswere made of two vents in the summit region, one of whichopened in 2010 and the other in 2012. We determined an av-erage SO2flux of 5.2±1.9 kg s−1using scanning ultravio-let spectroscopy, and molar proportions of H2O, CO2, SO2,HCl, CO and H2gases of 94.16, 4.03, 1.56, 0.23, 0.003 and0.009 % respectively by open-path Fourier transform infrared(FTIR) spectrometry and a multi-species gas-sensing system.Together, these data imply fluxes of 88, 8, 0.44, 5×10−3and1×10−3kg s−1for H2O, CO2, HCl, CO and H2respectively.Although H2S was detected, its concentration could not beresolved. HF was not detected. The chemical signature of thegas from both vents was found to be broadly similar. Follow-ing the opening of the 2010 and 2012 vents we found limitedto negligible interaction of the magmatic gas with the hy-drothermal system has occurred and the gas composition ofthe volcanic plume is broadly representative of equilibriumwith the magma. The time evolution of the gas composition,the continuous emission of large quantities of SO2, and thephysical evolution of the summit area with new vent open-ings and more frequent eruptions all point towards a continu-ous drying of the hydrothermal system at Turrialba’s summitat an apparently increasing rate.

Description: This research was supported by the RoyalGeographical Society (with IBG) with a Geographical FieldworkGrant. Y. Moussallam and N. Peters were additionally supportedby the Philip Lake funds from the Department of Geography,University of Cambridge. Y. Moussallam acknowledges a researchgrant from Mazamas and support through ERC project #279790.We thank the NERC Field Spectroscopy Facility for the loanof their infrared spectrometer. A. Aiuppa acknowledges supportthrough ERC grant no. 305377 (BRIDGE)

Description: Published

Description: 1341–1350

Description: 4V. Processi pre-eruttivi

Description: JCR Journal

Description: Questo studio viene proposto alle amministrazioni come metodologia geofisica integrata per il controllo e il monitoraggio del sottosuolo dei centri abitati. Lo studio della struttura geologica della conca e dei rilievi che la contornano insieme al successivo controllo ha portato a proporre una metodologia per prevenire in aree a rischio, il possibile sprofondamento.

Description: Published

Description: Rome, 3-4 December 2009

Description: 7A. Geofisica per il monitoraggio ambientale

Description: 7SR AMBIENTE – Servizi e ricerca per la società

Description: Vengono mostrati i primi risultati dei rilievi geofisici e geochimici nella zona di Guidonia che hanno consentito una caratterizzazione geologica e strutturale preliminare fornendo elementi utili per la comprensione della genesi del fenomeno di sprofondamento in atto e della sua evoluzione.

Description: Published

Description: 8 maggio 2014, Roma

Description: 7A. Geofisica per il monitoraggio ambientale

Description: 6SR VULCANI – Servizi e ricerca per la società

Description: La carta rappresenta una semplice guida alla visita dei luoghi più interessanti dal punto di vista paesaggistico e vulcanologico e fornisce anche informazioni utili sulle norme di comportamento da tenere per evitare eventuali pericoli. La visita è organizzata su due itinerari diretti rispettivamente al cratere della Fossa (percorso A) e ai coni di Vulcanello (percorso B). Lungo gli itinerari sono indicate delle fermate (stop) in punti dove possono essere fatte osservazioni interessanti della geologia locale o che offrono panorami di ampia prospettiva.

Description: DPC INGV

Description: Published

Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio

Description: N/A or not JCR

Description: The rheological properties of suspensions containing high solid fractions are investigated. Attention is focused on viscosity of silicate and magmatic melt systems. A general empirical equation which describes the relative viscosity of suspensions as a function of suspended solid fraction is proposed. In the limit of very dilute solid concentrations it reduces to the Einstein equation. The proposed relationship is satisfactorily applied to reproduce available experimental data relative to silicate melts. Moreover, the extrapolation of the model to very high concentrations is compared with experimental observations on partially‐melted granite.

Description: Published

Description: L22308

Description: 3V. Proprietà chimico-fisiche dei magmi e dei prodotti vulcanici

Description: JCR Journal

Description: Il Monte Amiata, ubicato nella porzione sud-occidentale della regione Toscana, è un edificio vulcanico che si è strutturato durante la parte finale del Pleistocene medio (350 - 200 ka; Laurenzi et al., 2015; Principe et al., 2018) al di sopra delle unità tettoniche strutturatesi durante le fasi mio-plioceniche dell’orogenesi appenninica. La distribuzione dei centri eruttivi sembra essere controllata da una zona di debolezza strutturale plio-pleistocenica, orientata circa NE-SW, che interessa sia i depositi vulcanici che le unità strutturali sottostanti (Brogi & Fabbrini, 2009, Brogi et al., 2015; Piccardi et al., 2017, Principe et al., 2018). Il gradiente geotermico è caratterizzato da valori molto alti (fino a 15°/100m), rendendo l’area particolarmente idonea per la produzione di energia geotermica. La produzione geotermica iniziò a partire dal 1960. Attualmente, gli impianti produttivi di ENEL- Greenpower di Bagnore e Piancastagnaio (Fig. 1), sfruttano un serbatoio geotermico collocato tra i 2000 e i 3500 metri di profondità rispetto al piano campagna. Il Catalogo Parametrico dei Terremoti Italiani (CPTI; Rovida et al., 2016 riporta, tra il 1287 e il 1940, 13 terremoti con una magnitudo equivalente compresa tra 4.5 £ Me £ 5.3 che hanno causato danneggiamenti fino al grado VIII MCS (Fig. 1), evidenziando un’attività sismica naturale e capace di causare seri danneggiamenti, ben prima dell’inizio dello sfruttamento geotermico dell’area. La sismicità recente, registrata dalla rete sismica nazionale dell’INGV (Castello et al., 2006; http://cnt.rm.ingv.it), riporta meno di 150 terremoti nell’area amiatina negli ultimi 25 anni, di cui 35 eventi con ML ≥ 1.5. Tra questi, il terremoto del 1.4.2000 (Md=4.0; http://cnt.rm.ingv.it/event/1132509) causò danni ad oltre 50 edifici, e la prossimità dell’epicentro con l’impianto di produzione di Piancastagnaio sollevò l’ipotesi di una sua natura antropogenica (Mucciarelli et al. 2001). Braun et al. (2018) hanno ricalcolato ipocentro e meccanismo focale di questo evento, collocandolo ad una profondità prossima al serbatoio di produzione, giungendo però alla conclusione che non sia possibile, per questa via, discriminare la sua natura antropogenica o meno. In generale, rispetto alle profondità tipiche della sismicità crostale osservata in Toscana (tra circa 5 e 13 km) gli ipocentri degli eventi sismici registrati nell’area amiatina hanno delle profondità simili a quelle di produzione (〈 5 km). La bassa densità della rete di monitoraggio INGV in quest’area del territorio nazionale (Fig. 1) è causa, comunque, di una bassa capacità di rilevazione (detection) sismica e di una altrettanto bassa capacità di risoluzione ipocentrale. Per migliorare le capacità di detection e di monitoraggio sismico nell’area del Monte Amiata, nel periodo 2015 - 2018 abbiamo installato una rete locale composta da 8 stazioni in vicinanza delle centrali di produzione geotermica di Bagnore e Piancastagnaio. L’obiettivo dell’esperimento era quello di abbassare la magnitudo di completezza e di comprendere meglio l’origine della sismicità in vicinanza degli impianti di estrazione, cercando di discriminare tra sismicità naturale e eventi sismici antropogenici. A questo scopo, abbiamo applicato una metodologia di analisi automatica, scansionando l’enorme dataset con un nuovo e robusto approccio di detection e localizzazione, chiamato waveform beam-forming grid search approach (LASSIE; Heimann et al., 2017). In uno step successivo, gli eventi sismici associati vengono rilocalizzati con un waveform-based locator (LOKI: Grigoli et al. 2014). Il catalogo sismico così ottenuto, aggiornato e molto più completo rispetto a quanto mai ottenuto prima in termini di Magnitudo di completezza (Mc), rappresenta la base per definire criteri di discriminazione, ad esempio attraverso la correlazione spazio-temporale della sismicità osservata con i parametri di produzione geotermica. I risultati ottenuti e le potenzialità di tale approccio saranno oggetto della presentazione qui proposta.

Description: Unpublished

Description: Roma

Description: 1TR. Georisorse

Description: The persistent open-vent mild explosive activity of Stromboli volcano is episodically interrupted by more violent and dangerous explosive events (major explosions and paroxysms). According to the nature of erupted products, paroxysms can be related either to the explosion of overpressured gas pockets located in the proximity of the magma column or to the sudden uprise of hot, gas-rich magma from a deep part of the plumbing system. In both cases, these more energetic explosive events should be preceded by an escape or a preferential uprise of the highly mobile volatiles which, in turn, should produce gas leakage anomalies at the surface in sites of high vertical permeability, such as deep-reaching faults. In order to identify such gas leaking sites, a systematic CO2 soil flux survey has been carried out on the island using an accumulation chamber. Four hundred sixty-one points have been measured with a high density in the summit crater area, where high flux values have been found (10−3–10−2 cm/s). Anomalous points are concentrated along the main NE–SW axial feeding system of the volcano. CO2 soil flux decreases from the crater zone to the base of the volcanic cone, where, however, an interesting gas leakage anomaly occurs (Pizzillo mofette). In the Pizzillo area thermal water wells also occur, whose chemistry indicates an origin by sea water heated by hot gas. Soil gases have been sampled in the sites with the highest CO2 flux in the crater area and at the base of the cone. Chemical and isotopic analyses indicate the presence of a deep gas component especially in the crater zone samples (high CO2, appreciable contents of He and H2, 3He/4He values up to 3.55, δ13C of CO2=−2 ‰). The SC5 low-flux fumarole on the crater rim has shown, during six years, a remarkable persistence of temperature (93–95°C), with only minor fluctuations of chemistry. Appearance of anomalous peaks of H2 in correspondence with strombolian explosions was observed during a 2-h 30-min experiment of continuous recording of hydrogen content of the fumarole. Together with previous data on H2O, CO2 and He, this experiment confirms that strombolian blasts produce rapid fluctuations in the fumarolic gas composition. In the light of this study, SC5 fumarole and Pizzillo mofette look promising sites for the testing of a continuous geochemical monitoring system of Stromboli volcano.

Description: Gruppo Nazionale per la Vulcanologia CEC project “Pre-eruptive processes: Modelling and Parameterization”, contract no. ENV4-CT96-0259 (DG12–ESCY)

Description: Published

Description: 226-245

Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio

Description: JCR Journal

Description: Tor Caldara natural reserve hosts the southernmost discharge of endogenous gas of Colli Albani volcano (mostly CO2 with a relevant H2S content up to 6.3 vol.%). Gas discharges in zones where past sulfur mining removed the impervious surficial cover (e.g. Miniera Grande and Miniera Piccola) and along tectonic fissures. A structural study of the reserve has shown the presence of two zones with different characteristics: prevailing directions NS and N30° in the northern zone; EW and N60° in the southern one. In MarchJuly 2012 a geochemical study was carried out, including a soil CO2 flux survey and continuous monitoring (from 2 to 11 days) of air concentration of CO2 and H2S in 12 sites of the reserve. Environmental parameters were also monitored. Total diffuse soil flux of endogenous CO2 was estimated to 17.48 ton*day1 from 1,259 measurements over a 0.47 km2 surface, with 6.56 ton*day1 only from Miniera Grande. This is the second highest value of soil CO2 flux at Miniera Grande, after that of 2005 (9.25 ton*day1) and is significantly higher than in 2009 (1.20 ton*day1). As both the 2005 and 2012 surveys were made shortly after earthquakes with epicentres near to Tor Caldara (max ML= 4.7 in 2005 and 3.5 in 2012), data confirm that soil CO2 flux increases during earthquakes because of seismic rock microfracturing and soil shaking. Hazardous air concentrations have been found only for H2S, up to immediately lethal values (5651,124 ppm) and with potentially lethal values (≥ 250 ppm) long persisting (up to 12h27’) in several no wind nights. Instead, the CO2 air concentration remained always well below dangerous levels (maximum recorded value = 2.1 vol.%). The most hazardous gas releasing sites were found in Miniera Grande and in a small pond NE of Miniera Piccola, where the carcasses of mammals and other small animals are frequently found. The killer gas is H2S, and the dangerous sites should be appropriately fenced to prevent access to people and animals.

Description: Regione Lazio Civil Protection Department

Description: Published

Description: 1-48

Description: 6A. Geochimica per l'ambiente e geologia medica

Description: JCR Journal

Description: FAIR principles have become reference criteria for promoting and evaluating openness of scientific data and for improving datasets Findability, Accessibility, Interoperability, and Reusability. This also applies to Research Infrastructures (RIs) in the solid Earth domain committed to provide access to seismological data, ground deformations inferred from terrestrial, and satellite observations, geological maps, and laboratory experiments. Such RIs have been indeed committed for a long time, well before the appearance of FAIR principles, to engage scientific communities involved in data collection, standardization, and quality control as well as in implementing metadata and services for qualification, storage and accessibility. By addressing open science and managing scientific data, they are working to adopt FAIR principles, thus having the onerous task of turning these principles into practices. In this work we argue that although FAIR principles have the merit of creating a common background of knowledge to engage communities in providing data in a standard way thus easing interoperability and data sharing, in order to make the adoption of FAIR principles less onerous there is an urgent need of clear models, reference architectures and technical guidelines which can support RI implementers in the realization of FAIR data provision systems. We therefore discuss the state of the art of FAIR principles ecosystem and open new perspectives by discussing a four-stages roadmap that reorganizes FAIR principles in a way that better fits to the approach of RI implementers, and a FAIR adoption process that relates FAIR principles to technologies for their implementation.

Description: Published

Description: id 3

Description: 4IT. Banche dati

Description: JCR Journal

Description: Data on the abundance and distribution of Anthropogenic Marine Debris (AMD) on the coastal areas of the northern Tyrrhenian coast are still scarce. The objective of this study is to characterize, in terms of size, color, morphology and polymeric nature, the Large Microplastics (LMPs), i.e., plastic objects within 1 and 5 mm, sampled on three beaches located within the coastal macro-area of the Pelagos Sanctuary, an international protected zone in the north-western Mediterranean. The beaches have similar morphological characteristics but different degrees of urbanization. LMPs were sampled seasonally for one year. The polymeric nature of a representative subsample of the collected LMPs was investigated using a portable Raman instrument, to assess the feasibility of in situ characterization. In this study, 26,486 items were sorted by typology (Expanded Polystyrene-EPS, fragments, and resin pellets), size, and for fragments and resin pellets, also by color and chemical nature. Statistical data on the quantity, density, type, spatial distribution, and seasonality of the sampled LMPs are presented. Differences in LMP abundance and composition were detected among sites. A seasonality trend emerges from our statistical analysis, depending on both LMP typology and urbanization degrees of the beaches. Our data do not show the existence of a relationship between the size of the investigated MPs and their color, while they suggest that the type of polymer influences the degree of fragmentation. This underlines the need to further investigate the mechanisms leading to the production and dispersion of MPs in coastal areas, taking into account both the urbanization of the beach, and therefore the possible sources of input, and the different types of MPs. Finally, a Raman portable instrument proved to be a valuable aid in performing in situ polymeric characterization of LMPs.

Description: Published

Description: id 3389

Description: 4A. Oceanografia e clima

Description: JCR Journal

Description: The SHARC Interest Group of the Research Data Alliance was established to improve research crediting and rewarding mechanisms for scientists who wish to organise their data (and material resources) for community sharing. This requires that data are findable and accessible on the Web, and comply with shared standards making them interoperable and reusable in alignment with the FAIR principles. It takes considerable time, energy, expertise and motivation. It is imperative to facilitate the processes to encourage scientists to share their data. To that aim, supporting FAIR principles compliance processes and increasing the human understanding of FAIRness criteria – i.e., promoting FAIRness literacy – and not only the machine-readability of the criteria, are critical steps in the data sharing process. Appropriate human-understandable criteria must be the first identified in the FAIRness assessment processes and roadmap. This paper reports on the lessons learned from the RDA SHARC Interest Group on identifying the processes required to prepare FAIR implementation in various communities not specifically data skilled, and on the procedures and training that must be deployed and adapted to each practice and level of understanding. These are essential milestones in developing adapted support and credit back mechanisms not yet in place.

Description: Published

Description: id 32

Description: 4IT. Banche dati

Description: N/A or not JCR

Description: Initial excess protactinium (231Pa) is a frequently suspected source of discordance in baddeleyite (ZrO2) geochronology, which limits accurate U/Pb dating, but such excesses have never been directly demonstrated. In this study, Pa incorporation in late Holocene baddeleyite from Somma-Vesuvius (Campanian Volcanic Province, central Italy) and Laacher See (East Eifel Volcanic Field, western Germany) was quantified by U-Th-Pa measurements using a large-geometry ion microprobe. Bad- deleyite crystals isolated from subvolcanic syenites have average U concentrations of ~200 ppm and are largely stoichiometric with minor abundances of Nb, Hf, Ti, and Fe up to a few weight percent. Measured (231Pa)/(235U) activity ratios are significantly above the secular equilibrium value of unity and range from 3.4(8) to 14.9(2.6) in Vesuvius baddeleyite and from 3.6(9) to 8.9(1.4) in Laacher See baddeleyite (values within parentheses represent uncertainties in the last significant figures reported as 1σ throughout the text). Crystallization ages of 5.12(56) ka (Vesuvius; MSWD = 0.96, n = 12) and 15.6(2.0) ka (Laacher See; MSWD = 0.91, n = 10) were obtained from (230Th)/(238U) disequilibria for the same crystals, which are close to the respective eruption ages. Applying a corresponding age correction indicates average initial (231Pa)/(235U)0 of 8.8(1.0) (Vesuvius) and 7.9(5) (Laacher See). For reasonable melt activities, model baddeleyite-melt distribution coefficients of DPa/DU = 5.8(2) and 4.1(2) are obtained for Vesuvius and Laacher See, respectively. Speciation-dependent (Pa4+ vs. Pa5+) partitioning coefficients (D values) from crystal lattice strain models for tetra- and pentavalent proxy ions significantly exceed DPa/DU inferred from direct analysis of 231Pa for Pa5+. This is consistent with predominantly reduced Pa4+ in the melt, for which D values similar to U4+ are expected. Contrary to common assumptions, baddeleyite-crystallizing melts from Vesuvius and Laacher See appear to be dominated by Pa4+ rather than Pa5+. An initial disequilibrium correction for baddeleyite geochronology using DPa/DU = 5 ± 1 is recommended for oxidized phonolitic melt compositions.

Description: Published

Description: 1830-1840

Description: 1V. Storia eruttiva

Description: 2V. Struttura e sistema di alimentazione dei vulcani

Description: 3V. Proprietà chimico-fisiche dei magmi e dei prodotti vulcanici

Description: JCR Journal

Description: We present three‐dimensional numerical simulations of eruption clouds from circular to linear fissure vents to investigate the control of vent shape on the height and stability of volcanic plumes during large explosive eruptions. Our results show that clouds ejected from circular or low‐aspect‐ratio (nearly square‐like) fissure vents can be associated with radially suspended flow (RSF) at the top of the jet region, whereas those emitted from narrow‐fissure vents are not. Non‐RSF plumes are more stable than those associated with RSF because the highly concentrated parts of the ejected mixture are easily dissipated and mixed with air near the vent. Plume height in the RSF regime decreases while that in the non‐RSF regime increases with increasing aspect ratio, even for a fixed magma flow rate. These observations suggest that the efficiency of air entrainment is influenced by the vent shape, which in turn controls the dynamics of eruption plumes.

Description: Published

Description: e2020GL087038

Description: 5V. Processi eruttivi e post-eruttivi

Description: JCR Journal

Description: The most recent eruptive activity of Turrialba volcano began on the 5th of January 2010, after more than a century of dormancy. The fragmentation process and aerodynamic behavior of the ash from Turrialba’s vulcanian eruptions were investigated by combining grain-size, petrography, mineralogy, Scanning Electron Microscopy (SEM) and Energy Dispersive System (EDS) analyses. The ash components include variable percentages of accessory fresh (no necessary juvenile) to hydrothermally altered lithics (15 - 50 % vol.) with hydrothermal minerals (≤ 12 % vol.: anhydrite, gypsum, bassanite, alunite, hexahydrite, pyrite, heulandite, native sulfur), clay minerals (8 - 17 % vol.: montmorillonite, halloysite, allophane), and a smaller quantity of fresh glassy ashes (5 - 49 % vol.) as fragments and shards (3 - 20 % vol. tackylite and 2 - 26 % vol. sideromelane), as well as primary and eroded/recycled phenocrysts (3 - 13 % vol.: 1 - 5% vol. plagioclase, 1 - 7 % vol. pyroxene, 0 - 1 % vol. olivine, 0 - 6 % vol. opaques, cristobalite and tridimite), and xenocrysts (≤ 1 % vol.: riebeckite and biotite). The secondary minerals were sourced from the deeper to surficial hydrothermal system. Textural features identified in ash particles (90 - 350 μm) suggest that they were formed by brittle fragmentation of vesicle-poor magma/water interaction; molten structures seems to be related to the ductile behavior of some fragments, probably due to the high temperature (〉 600 °C) of the fumarolic/magmatic system. The percentage of juvenile components was low (1 - 2 % vol.) at the first opening eruptive phase in January 2010, and it increased steadily until the end of 2016 (ca. 12 - 25 % vol.) . The ash eruptions in the Western Crater from 2014 to 2016 were related to one and later two or three simultaneously active vents fed by distinct conduit branches. The alternation of volcanic explosions (VEI: 0 - 2), from closed conduit and the formation of new craters, to open system with phreatomagmatic events, and the repose intervals (inter-eruptive exhalative degassing), were controlled by the rate at which magma ascended and remained in the volcanic edifice. The recent tephra sequence consists of a complex succession of layers generated by contrasting fragmentation and transportation dynamics. They resulted from fully diluted, low temperature (〈 300 °C), pyroclastic density currents (wet surge deposits), originated by short-lived, singlepulse, column collapse of phreatomagmatic columns, which traveled short distances (〈 1000 m) from the vent area and surmounted topographic obstacles, and simultaneous fallout and ballistic ejecta. The fine material, in continuous suspension within the uppermost part of the convective plume, was dispersed into the atmosphere and finally settled down on the Valle Central. The quiescent phases could be related to a temporal cooling of the magmatic dike system or to a waning of magmatic activity at depth. Sequential fragmentation/transport theory (SFT) was used to decompose grain-size distributions into five different sub-populations. A new way of using the resultant fragmentation coefficient to assign sub-populations to different fragmentation mechanisms, even in cases when modes overlapped, is presented. For the first time the corresponding results are consistent with the phreatomagmatic eruptions, as well as with those derived from ab initio fractal model.

Description: Published

Description: 7-60

Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio

Description: N/A or not JCR

Description: Globally, thermodynamics explains an increase in atmospheric water vapor with warming of around 7%/°C near to the surface. In contrast, global precipitation and evaporation are constrained by the Earth's energy balance to increase at ∼2-3%/°C. However, this rate of increase is suppressed by rapid atmospheric adjustments in response to greenhouse gases and absorbing aerosols that directly alter the atmospheric energy budget. Rapid adjustments to forcings, cooling effects from scattering aerosol, and observational uncertainty can explain why observed global precipitation responses are currently difficult to detect but are expected to emerge and accelerate as warming increases and aerosol forcing diminishes. Precipitation increases with warming are expected to be smaller over land than ocean due to limitations on moisture convergence, exacerbated by feedbacks and affected by rapid adjustments. Thermodynamic increases in atmospheric moisture fluxes amplify wet and dry events, driving an intensification of precipitation extremes. The rate of intensification can deviate from a simple thermodynamic response due to in-storm and larger-scale feedback processes, while changes in large-scale dynamics and catchment characteristics further modulate the frequency of flooding in response to precipitation increases. Changes in atmospheric circulation in response to radiative forcing and evolving surface temperature patterns are capable of dominating water cycle changes in some regions. Moreover, the direct impact of human activities on the water cycle through water abstraction, irrigation, and land use change is already a significant component of regional water cycle change and is expected to further increase in importance as water demand grows with global population.

Description: Published

Description: 49-75

Description: 4A. Oceanografia e clima

Description: JCR Journal

Description: Volcanoes with multiple summit vents present a methodological challenge for determining vent-specific gas emissions. Here, using a novel approach combining multiple ultraviolet cameras with synchronous aerial measurements, we calculate vent-specific gas compositions and fluxes for Stromboli volcano. Emissions from vent areas are spatially heterogeneous in composition and emission rate, with the central vent area dominating passive emissions, despite exhibiting the least explosive behaviour. Vents exhibiting Strombolian explosions emit low to negligible passive fluxes and are CO2-dominated, even during passive degassing. We propose a model for the conduit system based on contrasting rheological properties between vent areas. Our methodology has advantages for resolving contrasting outgassing dynamics given that measured bulk plume compositions are often intermediate between those of the distinct vent areas. We therefore emphasise the need for a vent-specific approach at multi-vent volcanoes and suggest that our approach could provide a transformative advance in volcano monitoring applications.

Description: Published

Description: id 3039

Description: 4V. Processi pre-eruttivi

Description: JCR Journal

Description: In this paper, we present results of the reconstruction of the total grain size distribution (TGSD) of the material erupted during explosive volcanic eruptions at Campi Flegrei (Italy) considering all components (juvenile, lithic and crystal clasts). To date, the few TGSDs made available have been mostly reconstructed by assuming that the tephra deposits consisted of only one component. This simplification can introduce substantial bias in the interpretation of magma fragmentation mechanisms and significantly affect ash dispersion forecasts, since each tephra component has specific aerodynamic characteristics. By means of field investigations and laboratory analyses on samples collected from deposits of the Agnano-Monte Spina and Astroni eruptions, we reconstructed the TGSDs of juvenile, lithic and crystal components via the Voronoi tessellation method. Our results show how the systematic reconstruction of a TGSD, from the component-specific to the bulk TGSD, can provide important information on magma fragmentation mechanisms and wall-rock erosion processes. Results confirm that the bulk TGSD is the combination of the merging of different component subpopulations, according to their own TGSD, density and relative mass proportions. In addition, the integration of component analysis, TGSD and settling velocity data allowed characterization of the aerodynamic behaviour of each component at variable distances from the vent, which can be related to their own parent grain size distribution. The integration of new data from distal tephra deposits for the considered eruptions has thus allowed a reassessment of the erupted volumes of eruptions considered in this research, which are now 3.17 and 0.63 km3, for Agnano-Monte Spina and Astroni, respectively.

Description: Published

Description: id 31

Description: 3V. Proprietà chimico-fisiche dei magmi e dei prodotti vulcanici

Description: JCR Journal

Description: probably confirm this opinion, with qualifica ons. Historical earthquake catalogues, up to CPTI11 [Rovida et al., 2011], report only one Mw 5.1 event on 13 November 1948: it was located in the Sardinian Sea, and had very modest effects on land. In later decades, the seismic networks did record very few earthquakes of moderate energy (Mw 〈5), mostly located off-shore, either south-east of Cagliari or west of Olbia or in the Sea of Sardinia. The most recent ones (occurred in 2000, 2004 and 2006) had very slight effects on the island. Given the low level of instrumental seismicity and the weak macroseismic effects of known historical earthquakes, Sardinia's seismic risk is perceived as very low. The low seismicity of the region certainly has a geological explana on, given that the Corsica-Sardinia block is among the most stable areas of the Mediterranean basin. “Low”, however, does not mean “non- existent”: recent historical research has improved knowledge on the major known historical earthquake of Sardinia (it occurred on June 4, 1616 and was responsible for minor but widespread damage to the system of coastal watchtowers, south-west of Cagliari) and rediscovered several minor earthquakes, part of which were known to the seismological tradi on but had been almost completely forgo en. This paper collects all the documenta on available at present on the seismic history of Sardinia.

Description: Published

Description: 1-160

Description: 4T. Sismicità dell'Italia

Description: JCR Journal

Description: Thermal-infrared remote sensing is used to monitor and study hazardous volcanic phenomena. Thermal cameras are often used by monitoring centers and laboratories. A physical comprehension of their behavior is needed to perform quantitative measurements, which are strongly dependent on camera features and settings. This makes it possible to control the radiance measurements related to volcanic processes and, thus, to detect thermal anomalies, validate models, and extract source parameters. We review the theoretical background related to the camera behavior beside the main features affecting thermal measurements: Atmospheric transmission, object emissivity and reflectivity, camera characteristics, and external optics. We develop a Python package, PythTirCam-1.0, containing pyTirTran, a radiative transfer model based on the HITRAN database and the camera spectral response. This model is compared with the empirical algorithm implemented into a commercial camera. These two procedures are validated using a simple experiment involving pyTirConv, an algorithm developed to recover the radiometric thermal data from compressed images collected by monitoring centers. Python scripts corresponding to the described methods are provided as open-source code. This study can be applied to a wide variety of applications and, specifically, to different volcanic processes, from earth and space.

Description: This research has received funding from the Italian MIUR project Premiale Ash-RESILIENCE (FOE 2015), from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 731070, and from Pianeta Dinamico INGV project.

Description: Published

Description: id 4056

Description: 5V. Processi eruttivi e post-eruttivi

Description: JCR Journal

Description: The aim of the paper is to present and discuss the results of an ambient vibration monitoring campaign conducted in the old town of Lucca, over the period 2015–2018. Despite the low level of the ambient vibrations in the historic center, using high-sensitivity instrumentation allowed the authors to measure and study the dynamic behavior of two medieval masonry towers: the San Frediano belfry and the Clock Tower. The main results of the dynamic identification of the towers are summarized, together with the variation over time of their dynamic properties. Some insights on the towers' response to the anthropic activities in the historic center are also presented. Finally, a finite element simulation is performed with the aim of assessing the influence of temperature variations on the towers' natural frequencies; good agreement is found between numerical and experimental results. The paper provides the scientific and technical community with a detailed report on a singular experiment in the field of architectural heritage.

Description: Fondazione Cassa di Risparmio di Lucca (TITANIO project, 2016–2018) and the Region of Tuscany and MIUR (MOSCARDO project, FAR-FAS 2014, 2016–2018)

Description: Published

Description: Article 9

Description: 5T. Sismologia, geofisica e geologia per l'ingegneria sismica

Description: JCR Journal

Description: Making communities safer requires better tools to identify, quantify, and manage risks. Among the most important tools are stress tests, originally designed to test the risk posed by nuclear power plants. A complementary harmonized multilevel stress test for nonnuclear civil infrastructure systems against natural hazards is proposed. Each stress test level is characterized by a different scope and a different level of risk analysis complexity to suit different civil infrastructure systems, different hazards, and different risks. The stress test consists of the following phases. First, the goals and the methods for the risk analysis are defined. The test is then performed at the component and system levels, followed by a verification of the findings. A penalty system is defined to adjust the output of the risk assessment according to the limitations of the risk analysis methods used. The adjusted risk assessment results are then passed to a grading system to determine the outcome of the stress test. Finally, the risk assessment results are reported, and the stress test outcomes are communicated to stakeholders and authorities.

Description: Published

Description: 5T. Sismologia, geofisica e geologia per l'ingegneria sismica

Description: 6T. Studi di pericolosità sismica e da maremoto

Description: 1SR TERREMOTI - Sorveglianza Sismica e Allerta Tsunami

Description: JCR Journal

Description: Infrasound is an increasingly popular tool for volcano monitoring, providing insights of the unrest by detecting and characterizing acoustic waves produced by volcanic processes, such as explosions, degassing, rockfalls, and lahars. Efficient event detection from large infrasound databases gathered in volcanic settings relies on the availability of robust and automated workflows. While numerous triggering algorithms for event detection have been proposed in the past, they mostly focus on applications to seismological data. Analyses of acoustic infrasound for signal detection is often performed manually or by application of the traditional short-term average/long-term average (STA/LTA) algorithms, which have shown limitations when applied in volcanic environments, or more generally to signals with poor signal-to-noise ratios. Here, we present a new algorithm specifically designed for automated detection of volcanic explosions from acoustic infrasound data streams. The algorithm is based on the characterization of the shape of the explosion signals, their duration, and frequency content. The algorithm combines noise reduction techniques with automatic feature extraction in order to allow confident detection of signals affected by non-stationary noise. We have benchmarked the performances of the new detector by comparison with both the STA/LTA algorithm and human analysts, with encouraging results. In this manuscript, we present our algorithm and make its software implementation available to other potential users. This algorithm has potential to either be implemented in near real-time monitoring workflows or to catalog pre-existing databases.

Description: This research was partially funded by KNOWAVES TEC2015- 68752 (MINECO/FEDER), by NERC Grant NE/P00105X/1, by Spanish research grant MECD Jose Castillejo CAS17/00154 and by VOLCANOWAVES European Union’s Horizon 2020 Research and Innovation Programme Under the Marie Sklodowska-Curie Grant Agreement no 798480.

Description: Published

Description: Article 335

Description: 4V. Processi pre-eruttivi

Description: JCR Journal