ALBERT

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: 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: 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: 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: 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: 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: Surface tension plays an important role in the nucleation of H2O gas bubbles in magmatic melts and in the time-dependent rheology of bubble-bearing magmas. Despite several experimental studies, a physics based model of the surface tension of magmatic melts in contact with H2O is lacking. This paper employs gradient theory to develop a thermodynamical model of equilibrium surface tension of silicate melts in contact with H2O gas at low to moderate pressures. In the last decades, this approach has been successfully applied in studies of industrial mixtures but never to magmatic systems. We calibrate and verify the model against literature experimental data, obtained by the pendant drop method, and by inverting bubble nucleation experiments using the Classical Nucleation Theory (CNT). Our model reproduces the systematic decrease in surface tension with increased H2O pressure observed in the experiments. On the other hand, the effect of temperature is confirmed by the experiments only at high pressure. At atmospheric pressure, the model shows a decrease of surface tension with temperature. This is in contrast with a number of experimental observations and could be related to microstructural effects that cannot be reproduced by our model. Finally, our analysis indicates that the surface tension measured inverting the CNT may be lower than the value measured by the pendant drop method, most likely because of changes in surface tension controlled by the supersaturation.

Description: Published

Description: 113-127

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

Description: JCR Journal

Description: This paper reports the analysis of soil 222Rn data recorded over 7-years in the volcanic caldera of Campi Flegrei (Naples-Italy). The relationship between Radon activity concentration and several geophysical, geochemical and meteorological parameters, influencing the gas emissions, is estimated by the Artificial Neural Network (ANN) method. The analysis goals are: the estimation (replication) of the Radon time series from influencing parameters, the forecasting of an unknown part of it, and the search for anomalies. Results prove: (i) the effectiveness of the ANN method; (ii) Radon follow the periods of agitation of the caldera, demonstrated by the comparison with previous works using different methods.

Description: Published

Description: 109239

Description: 6IT. Osservatori non satellitari

Description: JCR Journal

Description: In their comments Bonini et al. argue that our seismotectonic interpretation of the Emilia 2012 seismic sequence does not agree with observations, and follow three lines of arguments to support their statement. These concern the structural interpretation of seismic reflection profiles, the relationship between seismogenic sources and seismicity patterns, and the fit of inferred fault geometry to InSAR observations. These lines of arguments are mostly repeating what has been previously presented by the same authors, and none of them, as discussed in detail in our reply, presents a strong case against our structural interpretation, that, we are convinced, does not conflict with the available data. The two adjacent rupture surfaces outlined by accurately relocated aftershocks are an indication of the presence of two different active fault planes. Interpretation of seismic profiles supports seismological observation and indicates the occurrence of relevant along-strike changes in structural style. These pieces of information have been integrated to build a new seismotectonic interpretation for the area of the Emilia 2012 seismic sequence. Analysis of geodetic data from the area of the Emilia earthquakes has produced very different models of the fault planes; unlike what has been stated by Bonini et al., who see a difficult fit to InSAR data for the fault planes we have identified, the most recent results are consistent with our interpretation that see a steep fault in the upper 8–10 km under the Mirandola anticline. We point out that the geological structures in the subsurface of the Ferrara Arc do change along strike, and the attempt of Bonini et al. to explain both the May 20 and May 29 sequences using a single cross section is not appropriate.

Description: Published

Description: 157-162

Description: 1T. Struttura della Terra

Description: JCR Journal

Description: Seismic microzonation represents a basic tool for prevention activity planning and land management. An extensive and detailed microzonation study was performed with reference to the territory of the Municipality of Cavezzo, damaged during the seismic sequence hitting Emilia-Romagna Region, Northern Italy, in 2012. In this paper, we discuss the work carried out to characterize the spatial variability of ground motion amplification due to local soil conditions in the municipality area. An inter- and multi-disciplinary approach is presented, involving geotechnical engineers, geophysicists, geologists and seismologists from different institutions, to thoroughly characterize the territory using complementary techniques with different level of resolution and confidence. A considerable amount of geomorphological, geological, hydrogeological, seismological, geotechnical and geophysical investigations was collected and processed for the purpose. A GIS-based (Geographic Information System) platform was initially setup to manage the gathered data, which now includes the results of about 1000 geotechnical and geophysical tests. Such an extended dataset was then used as a primary constraint for the creation of a comprehensive pseudo-3D geotechnical and seismo-stratigraphic model of the territory, consisting of a dense grid of one-dimensional vertical profiles to depict the variability of the soil properties over the area. The model was finally used as input for linear-equivalent ground response analysis. For the calculation of the amplification factors, special emphasis was given to the treatment and propagation of the uncertainties of the model parameters, whose different realizations have been accounted through a logic tree approach.

Description: Published

Description: 105722

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

Description: JCR Journal

Description: In the last years, monitoring systems based on low-cost and miniaturized sensors (MEMS) revealed as a very successful compromise between the availability of data and their quality. Also applications in the field of seismic and structural monitoring have been constantly increasing in term of number and variety of functions. Among these applications, the implementation of systems for earthquake early warning is a cuttingedge topic, mainly for its relevance for the society as millions of peoples in various regions of the world are exposed to high seismic hazard. This paper introduces the optimization of an already established seismic (and structural) monitoring system, that would make it suitable for the implementation of the earthquake early warning. In particular, the sampling code has been improved and a new triggering algorithm able to automatically detect the ground shaking due to the propagation of the seismic waves has been developed. The preliminary results indicate that the system is very flexible and easy to implement, and encourage to perform further developing steps.

Description: Published

Description: 963-975

Description: Cagliari

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

Description: The largest earthquake in the Zagros Mountains struck the city of Azgeleh on the Iran–Iraq border on 12 November 2017. This Mw 7.3 earthquake was followed by an intense seismic sequence. Implementing the double-difference earthquake location technique, we relocate 1069 events recorded by our local seismic network, deployed after the mainshock. The spatial distribution of the epicenters indicates linear alignments of the events nucleated along at least four notable clusters. The clusters are characterized by at least one significant earthquake, such as the Tazehabad earthquake of 25 August 2018 (Mw 5.9) along a dense, east–west trending cluster and the Sarpol-e Zahab earthquake of 25 November 2018 (Mw 6.3) along the cluster with a northeast–southwest trend. We use two-pass differential SAR interferometry (DInSAR) and Small BAseline Subset (SBAS) methods to study the coseismic permanent displacements of the Azgeleh, Tazehabad and Sarpol-e Zahab events as well as the one-year postseismic deformation field of the 2017–2018 seismic sequence, respectively. We use non-linear and linear optimization algorithms to derive the source geometry and the slip distribution along the fault planes. The inversion is conducted by introducing also seismological constraints, leading to the definition of a listric geometry for the Azgeleh mainshock rupture that accommodates the slip area at depth of 10–16 km along a sub-horizontal plane (dipping ~3°) and a low-angle (~16°) ramp. The thrust and dextral movements along this NNW-striking (~345°) fault have triggered a tear fault responsible for the Tazehabad event ruptured an east–west trending (~267°), north-dipping (~78°) sinistral shear fault. We present the dextral slip distribution of the Sarpol-e Zahab event along a NE-striking (~34°) fault, as a synthetic Riedel structure for the southern segment of the Khanaqin fault, dipping 63° to the southeast. We find the postseismic deformation field associated with the seismic sequence is not confined only to the mainshock source (the Azgeleh fault), but also develops along the Tazehabad and Sarpol-e Zahab faults. We additionally propose afterslip along a duplex, flat-ramp-flat structure down-dip and up-dip of the Azgeleh coseismic slip area. The up-dip afterslip develops onto the shallow detachment (~3°) at depth of ~8 km and the down-dip afterslip propagate onto the mid-crustal décollement level within the Pan-African basement. The Azgeleh, Tazehabad, Sarpol-e Zahab and Khanaqin faults mark the Lurestan Arc–Kirkuk Embayment sharp margin in the Northwest Zagros and play a key role in the lateral escape of the Lurestan Salient and vertical strain partitioning in the Zagros front.

Description: Published

Description: 112224

Description: 2T. Deformazione crostale attiva

Description: JCR Journal

Description: Reducing the impact of volcanic eruptions on society is a major challenge of volcanology. Although science is one basic component of risk reduction, the achievement of this goal requires competencies that go beyond natural sciences. Nowadays, the importance of non-scientific factors in reducing volcanic risks is often and dangerously overlooked, possibly leading to decision making that cannot be rationally justified. In this paper we explore the basic components of an ideal decision-making process, identifying the roles and responsibilities of the different partners/tasks that are involved. In particular, we advocate the use of the hazard/risk separation principle, which can help discern unambiguously the role of volcanology (and more in general of science) in the whole risk-reduction process. Although this distinction may be of low relevance in some real cases—for example, when the costs of mitigation actions are low and the likelihood of eruption is high—it becomes of paramount importance when dealing with high uncertainty on the eruption onset or size and expensive mitigation actions, such as the evacuation of a large city. Volcanologists can play different roles in the decision-making process, but they have to be aware that this demands competencies that go beyond being a good volcano scientist. The final intent of this paper is to encourage constructive cooperation between volcanologists and public-policy makers keeping separated their own tasks as defined by their roles and their competences, with the intent of establishing fully transparent decision-making protocols well before volcanic crises. These protocols can be very helpful to audit the decision-making process at any time, and they may be an excellent communication tool for the interested stakeholders, including society.

Description: Published

Description: 545-564

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

Description: Geological gas seepage in petroleum-bearing sedimentary basins is an important natural source of atmospheric methane. In methane budget models geological emissions are generally considered constant over time, not affecting decadal atmospheric methane changes. Here, we report the case of a considerable sub-decadal variation of methane seepage from one of the largest thermogenic gas seep sites in Europe, Katakolo Harbour (Western Peloponnese, Greece). Based on gas flux measurements by accumulation chamber performed in 2010 and 2018, methane emission from cracks and fissures throughout the asphalt and concrete pavement of the harbour increased about four times (from 57 to 225 kg d􀀀 1) with emission factor changing from ~4,000 to 15,000 t km􀀀 2 y􀀀 1. Multiple lines of evidence, including mechanical deformation and fissuring of concrete and asphalt pavement, increased exhalation with constant fissure conditions, and no significant cracking with operating corrosion from 2004 to 2010, suggest that the methane emission increase is mainly due to intensification of subsurface gas flow (seepage) after 2010. Deep gas pressure and fault permeability variations, likely induced by the numerous earthquakes of the region, might have played a role. We estimate that if similar short-term variations of emission factor occur in large seepage areas worldwide, the global geological methane emission can significantly change, contributing to decadal changes of atmospheric methane budget.

Description: Published

Description: 104578

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

Description: JCR Journal

Description: None

Description: Published

Description: 301-312

Description: 2A. Fisica dell'alta atmosfera

Description: The aim of this paper is to identify the ground motion models (GMMs), applicable in active shallow crustal regions (ASCRs) and subduction zones (SZs), to be used for the new release of the seismic hazard model of Italy (MPS19) for peak ground acceleration and 12 ordinates of the acceleration response spectra (5% damping) in the period range 0.05–4 s. The steps to achieve such goal are: (1) a pre-selection of the GMMs that takes into account the suitability for the application to the Italian territory and the fulfillment of the new hazard model requirements; (2) the assessment of a proper scoring of the pre-selected GMMs using strong-motion data recorded in Italy; (3) the selection of the GMMs to be used in the hazard calculation. The final set of GMMs describes satisfactorily the epistemic uncertainty of the ground shaking process, privileging the simplicity and flexibility of the functional form. Finally, the weights of the selected GMMs are assigned combining the results of the scoring and the weights obtained through an experts’ elicitation.

Description: Published

Description: 3487–3516

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

Description: JCR Journal

Description: Integration of archaeoseismic observations, geological and geophysical surveys and a critical review of historical written sources contributed to shed light on the effects of the 847 earthquake AD that struck a large area of Southern-Central Italy. New archaeoseismic evidence of a strong earthquake comes from two Medieval archaeological sites along the Volturno Valley, between Campania and Molise regions, which occurred around the middle of the ninth century AD. Evidence includes the tilting of pillars in the Basilica of Santa Maria near Alvignano (northern Campania) and a collapsed masonry wall in the Abbey of San Vincenzo al Volturno near Isernia (northern Molise). At Alvignano, a site so far unrecorded in seismic catalogues for the 847 earthquake, geoelectrical and georadar investigations were used to explore the subsoil and study local site conditions, which could have influenced coseismic ground motion. Integrated interpretation of geophysical surveys and borehole logs document the presence of altered pyroclastic deposits, which certainly enhanced site effects at Alvignano. Analysis of damage descriptions and of archaeological reports indicate that the 847 seismic event documented by historical sources damaged a wide area between Latium, Campania and Molise, with destruction of the town of Isernia. Although historical sources did not explicitly mention damage in Rome, seismic effects attributed to the 847 event are recorded in the archaeological and seismological literature. Because the damaged area for this medieval earthquake is loosely defined due to the scanty documentation, the present study represents an important contribution to better define the shaking area and provide new hints on the extent and location of the possible seismogenic source.

Description: Published

Description: 228301

Description: 4T. Sismicità dell'Italia

Description: JCR Journal

Description: Seismic refraction, multichannel analysis of surface waves (MASW) and ambient noise array measurements using the wireless array analysis (WARAN) system were applied to acquire near-surface profiles of seismic velocities in the Selinunte Archaeological Park. This ancient city is famous for numerous temples, which according to the literature, were destroyed by at least two earthquakes in antiquity. The morphology of the archeological park is affected by two rivers which in combination with the temple remains suggests three study sites. We determined the subsurface velocity at these three locations as essential information for further studies of the response of the temple structures to earthquake ground motions. The stratigraphy of the site indicates that low-velocity layers might exist. Seismic refraction profiles with 69 m spread and 24 geophones were employed during the active seismic experiments. The measured P-wave velocities of the top two layers were used as a constraint during the inversion of dispersion relations from the MASW and WARAN data. The reliability of the velocity profiles was tested by forward calculation of synthetic seismograms. P-wave velocities which were not well constraint throughout the dispersion curve inversions were adjusted through suitable Poisson’s ratios based on the well constraint S-velocities. The combined use of the three different kinds of measurements and multi-mode interpretation of the dispersion curves revealed velocity profiles including lowvelocity layers which are supported by de-amplification observed in ratios of horizontal and vertical components of noise spectra.

Description: Published

Description: 753–776

Description: 7A. Geofisica per il monitoraggio ambientale

Description: JCR Journal

Description: The study of medium-large magnitude and intermediate-high intensity (VEI = 4/5; Column Height 15-20 km) eruptions fed by poorly evolved magmas is one of the main topics in volcanology. In this framework, the 472 CE (Pollena) eruption from Somma-Vesuvius (Italy) represents a key case study, as it is one of the subplinian eruptions used to constrain the reference scenario adopted by the Italian Department of Civil Protection in case of renewal activity at Somma-Vesuvius. The Pollena eruption experienced a complex dynamics, with abrupt shifts in eruptive style. This study focused on the fall products (L1- L8) of the magmatic eruptive phases (Phases I and II), which preceded the onset of the final phreatomagmatic phase (Phase III). Phase I was characterized by unsteady magma discharge resulting in an oscillating convective column, whereas Phase II involved pulsating activity with alternation of sustained and collapsing columns. To evaluate the role of textural variability in controlling magma rheology (and therefore variations in magma discharge), a detailed textural analysis of the juvenile products has been performed. Pyroclast textures record a variable degree of outgassing efficiency and lateral textural stratification of magma in the conduit, related to differential magma ascent rates and resulting in variable eruption intensity. Repetitive patterns of magma densification, achieved by progressive outgassing and crystallization, led to stages of decreasing ascent velocity resulting in the end of the eruptive pulse (during the oscillatory Phase I) or anticipating PDC emplacement (at the end of Phase I and during the pulsatory Phase II). Further decompression of the outgassed magma induced intense clinopyroxene microlite crystallization, that markedly increased magma viscosity and promoted the restoration of sustained columns during the eruption climaxes (L3 and L8). Magma densification patterns and consequent unsteadiness in magma discharge at the surface may derive from small heterogeneities in the initial volatile budget and/or represent a natural evolution of low viscosity magmas, as those feeding Pollena eruption, where efficient crystallization in the conduit can deeply and abruptly modify magma rheology, outgassing ability, conduit flow and, ultimately, eruptive style.

Description: Published

Description: 105658

Description: 5V. Processi eruttivi e post-eruttivi

Description: JCR Journal

Description: Mapping the static gravity field in the Italian area is fundamental to identify the main lithospheric structures, to delineate the main geological elements at regional level and to infer the regional geodynamic setting. The ongoing tectonic processes highlight nevertheless the need to measure and model the time-variable gravity field, namely the dynamic gravity field, which requires increased accuracy and long time series of observations to separate the secular from the short-term variable components. The first, with a minor impact in Italy, are due to variations of ice mass balance (the viscoelastic response of the Earth to past changes in ice mass loading, and the elastic response of the Earth to present-day deglaciation), and the sealevel rise; the second are due to space/time variations of underground mass distributions, such as those related to seismic deformations, volcanic dynamics/eruptions and water transfer. Local-scale gravity studies along seismogenic faults may provide useful hints to study the seismic cycle and to unravel those areas more prone to seismic release by studying if the crustal volume is undergoing dilatancy (gravity decrease) or overpressure (gravity increase) before earthquake occurrence. This process, however, is accompanied by possible fluid migration, which can be revealed by other geophysical measurements, for example, by magnetotelluric and geoelectrical surveys. In this short paper, we briefly summarize the main sources of gravity variation providing on the same time orders of magnitude, spatial and temporal scales of their effects.

Description: Published

Description: 549-558

Description: 2T. Deformazione crostale attiva

Description: JCR Journal

Description: Ocean acidification is one of the most dramatic effects of the massive atmospheric release of anthropogenic carbon dioxide (CO2) that has occurred since the Industrial Revolution, although its effects on marine ecosystems are not well understood. Submarine volcanic hydrothermal fields have geochemical conditions that provide opportunities to characterise the effects of elevated levels of seawater CO2 on marine life in the field. Here, we review the geochemical aspects of shallow marine CO2-rich seeps worldwide, focusing on both gas composition and water chemistry. We then describe the geochemical effects of volcanic CO2 seepage on the overlying seawater column. We also present new geochemical data and the first synthesis of marine biological community changes from one of the best-studied marine CO2 seep sites in the world (off Vulcano Island, Sicily). In areas of intense bubbling, extremely high levels of pCO2 ([10,000 latm) result in low seawater pH (\6) and undersaturation of aragonite and calcite in an area devoid of calcified organisms such as shelled molluscs and hard corals. Around 100–400 m away from the Vulcano seeps the geochemistry of the seawater becomes analogous to future ocean acidification conditions with dissolved carbon dioxide levels falling from 900 to 420 latm as seawater pH rises from 7.6 to 8.0. Calcified species such as coralline algae and sea urchins fare increasingly well as sessile communities shift from domination by a few resilient species (such as uncalcified algae and polychaetes) to a diverse and complex community (including abundant calcified algae and sea urchins) as the seawater returns to ambient levels of CO2. Laboratory advances in our understanding of species sensitivity to high CO2 and low pH seawater, reveal how marine organisms react to simulated ocean acidification conditions (e.g., using energetic tradeoffs for calcification, reproduction, growth and survival). Research at volcanic marine seeps, such as those off Vulcano, highlight consistent ecosystem responses to rising levels of seawater CO2, with the simplification of food webs, losses in functional diversity and reduced provisioning of goods and services for humans.

Description: Published

Description: 93–115

Description: 2IT. Laboratori analitici e sperimentali

Description: JCR Journal

Description: Radon monitoring represents an important investigation tool for environmental changes assessment and geochemical hazard surveillance. Despite anomalous radon emissions are commonly observed prior to earthquakes or volcanic eruptions, radon monitoring alone is not yet successful in correctly predicting these catastrophic events because contrasting radon signals are unexpectedly measured by lithologically distinct areas. This contribution aims to summarize and integrate natural and laboratory studies pertaining to the transport behavior of radon in different rock types experiencing variable stress and thermal regimes at subvolcanic conditions. The final purpose is to ignite novel and pioneer experimental researches exploring the causes and consequences of radon anomalous emissions, in order to elucidate in full the relationship between the physicochemical changes in substrate rocks and the radon signal.

Description: Published

Description: 309-328

Description: 4V. Processi pre-eruttivi

Description: The investigation of soil response to dynamic loads is necessary to predict site-specific seismic hazard. This paper presents the results of cyclic and dynamic laboratory tests carried out after the 2016–2017 Central Italy Earthquake sequence, within the framework of the seismic microzonation studies of the most damaged municipalities in the area. The database consists of 79 samples investigated by means of dynamic resonant column tests, cyclic torsional shear tests or cyclic direct simple shear tests. Results are firstly analysed in terms of field and laboratory values of small-strain shear wave velocity, highlighting the influence of the sample disturbance and of the mean effective consolidation pressure. The cyclic threshold shear strains as a function of plasticity index are then compared with findings from the published literature and the outliers are analysed. Subsequently, the dynamic soil behaviour is investigated with reference to the small-strain damping ratio. Differences between results from different tests are analysed in the light of the loading frequencies. Finally, the database is used to develop a predictive model for soil nonlinear curves according to plasticity index, mean effective confining stress, and loading frequency. The model represents a useful tool to predict the nonlinear stress–strain behaviour of Central Italy soils, necessary to perform site-specific ground response analyses.

Description: Published

Description: 5503–5531

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

Description: JCR Journal

Description: No abstract

Description: Published

Description: 5415–5422

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

Description: JCR Journal

Description: Since 1938, Nyamulagira volcano (Democratic Republic of Congo) has operated as a classic pressurized basaltic closed system, characterized by frequent dike-fed flank eruptions. However, on June 24, 2014, an active lava lake was observed in its summit, after a period of 76 years. The small lava lake is now exposed at the bottom of a pit-crater and is rising and growing. Based on satellite-derived infrared (IR) data, SO2 fluxes and periodic field surveys, we provide evidence that the development of the lava lake was gradual and occurred more than 2 years before it was first observed in the field. Notably, this process followed the voluminous 2011–2012 distal flank eruption and was coeval with weakening of the central rock column below the summit. Hence, the opening and development of the pit-crater favoured the continuous rise of fresh magma through the central conduit and promoted the gradual “re-birth” of the Nyamulagira lava lake. Budgeted volumes of magma erupted, and magma degassed at depth indicate that the formation of the lava lake is due to the draining and refilling of a shallow plumbing system (1–2 km depth), probably in response to the rift-parallel 2011–2012 distal eruption. We thus suggest that the transition from lateral to central activity did not result from a substantial change in the magma supply rate but, more likely, from the perturbation of the plumbing system (and related stress field) associated with the distal eruption. The processes observed at Nyamulagira are not unique and suggest that rift-fissure eruptions, in addition to triggering caldera collapses or lava lake drainages, may also induce a progressive resumption of central vent activity. Current activity at Nyamulagira represents a tangible and major hazard for the population living at the base of its southern flank.

Description: Published

Description: 20

Description: 5V. Processi eruttivi e post-eruttivi

Description: JCR Journal

Description: The origin and patterns of groundwater salinity of a shallow coastal aquifer pertaining to a reclaimed subsiding zone of the Po Delta are examined in this study. The aim is to identify the source of the hypersaline groundwater residing in the basal portion of the aquifer and to infer the mechanism of salinization of the remaining portion of the aquifer. To disentangle the possible sources of salinity the molar ratio of environmental tracers like Cl− and Br− were used in combination with the classical geochemical analyses of major and minor cations ratios. High-resolution multi-level sampling (MLS) allowed obtaining a robust and self-consistent hydrogeochemical database, which was statistically analysed via factor analysis and proved to be log-normally distributed. Thus, a common origin could be inferred for the elevated salinity that characterize most of the groundwater samples, this can be recognized in the organic rich fine-grained sediments, deposited in salty back barrier and marsh environments during the last transgression phase. This study proves that a detailed analysis of groundwater geochemistry can be considered a valuable tool to assess the origin of salinity in coastal Holocene aquifers, where the traditional conceptual model of a simple fresh/seawater interface may not be adequate.

Description: Published

Description: 130-137

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

Description: JCR Journal

Description: In February 2016, 47 ingots were found in the seabed of Contrada Bulala (Gela, CL, Italy) near the site where 40 ingots had previously been recovered. The ingots composition was determined to be a Cu - Zn alloy, dated by the archaeologist to the VI century B.C. This specific alloy was then known as Orichalcum. From an archaeological point of view, the first question raised about the new discovery was whether the ingots of the first and the second excavations belonged to the same shipwreck. Following the previous study, an elemental analysis was performed on the ingots from the second finding by using ICP-OS and ICP-MS techniques. The chemometric treatment of the analytical results obtained on both sets, i.e. ingots from first and second discovery, confirms their similarity. Therefore, the two findings can be considered to belong to the same naval load. The lead isotopic ratios were determined on selected/representative ingots to improve the knowledge about this treasure. Results can provide information about probable location of the lead sources, that could be very useful for the reconstruction of the ancient trade routes in the Mediterranean Sea.

Description: Published

Description: 102901

Description: 2IT. Laboratori analitici e sperimentali

Description: JCR Journal

Description: In the last years, because of uncontrolled human activities, a significant increase of groundwater pollution occurred worldwide, with nitrate being among the most widespread pollutants. The assessment of groundwater vulnerability represents an important tool for developing groundwater quality plans and in the delimitation of “Nitrate Vulnerable Zones”. In this study, three rating methods (DRASTIC, SINTACS and GOD) were applied in an alluvial plain to check the reliability of the results comparing the obtained thematic maps with the observed nitrate concentrations in groundwater. Results show that without large modifications for specific vulnerability, these methodologies cannot describe the actual groundwater nitrate distribution in the study area. A new easy methodology called Protection from Natural and Anthropogenic sources (PNA) was then defined and tested. The PNA map divides the study area in five classes of vulnerability from very low to very high and shows a fair correlation with groundwater nitrate concentrations. The selection of the parameters and of the algorithm makes PNA strongly flexible and applicable in similar watersheds around the world, as a tool for the delineation of “Nitrate Vulnerable Zones”.

Description: Published

Description: 104

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

Description: JCR Journal

Description: Shallow aquifers are the most accessible reservoirs of potable groundwater; nevertheless, they are also prone to various sources of pollution and it is usually difficult to distinguish between human and natural sources at the watershed scale. The area chosen for this study (the Campania Plain) is characterized by high spatial heterogeneities both in geochemical features and in hydraulic properties. Groundwater mineralization is driven by many processes such as, geothermal activity, weathering of volcanic products and intense human activities. In such a landscape, multivariate statistical analysis has been used to differentiate among the main hydrochemical processes occurring in the area, using three different approaches of factor analysis: (i) major elements, (ii) trace elements, (iii) both major and trace elements. The elaboration of the factor analysis approaches has revealed seven distinct hydrogeochemical processes: i) Salinization (Cl-, Na+); ii) Carbonate rocks dissolution; iii) Anthropogenic inputs (NO3-, SO42-, U, V); iv) Reducing conditions (Fe2+, Mn2+); v) Heavy metals contamination (Cr and Ni); vi) Geothermal fluids influence (Li+); and vii) Volcanic products contribution (As, Rb). Results from this study highlight the need to separately apply factor analysis when a large data set of trace elements is available. In fact, the impact of geothermal fluids in the shallow aquifer was identified from the application of the factor analysis using only trace elements. This study also reveals that the factor analysis of major and trace elements can differentiate between anthropogenic and geogenic sources of pollution in intensively exploited aquifers.

Description: Published

Description: 260-269

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

Description: JCR Journal

Description: Primitive basalticmagmas are crucial in the study of the geochemical heterogeneity documented in Etnamagmas and their inferred mantle sources. We undertook a systematic sampling of the less evolved basalts (Mg# N50) erupted over the last 15 ka, a time period which corresponds to the activity of the youngest volcanic edifice of Mt. Etna complex, i.e. Mongibello volcano. We focused on lava flows and pyroclastites emplaced during ‘deepdyke fed’ (DDF) eruptions which were driven by the rapid ascent of deeply-rooted magma intrusions that bypassed the shallow plumbing system of the volcano. All the samples were analyzed by the same laboratory to avoid analytical bias, to build a comprehensive dataset on their major and trace element compositions and to propose a coherent framework for interpreting the geochemical fingerprints of present-day Etna basalts. Trace element modeling, togetherwith literature data for Sr isotopes, gave insight into long-term magmatic processes related to different melting degrees of the heterogeneous mantle beneath Mt Etna. DDF magma batches provide good snapshots of their mantle source heterogeneities that point to the variable involvement of clinopyroxenitic lithology, Rb–87Sr–Cl-rich fluid component(s) possibly controlled by their source mineralogy, and slab-derived fluids selectively enriched in alkalis (Rb, K). The ongoing alkali (Rb, K) enrichment of the present-day magmas, well manifest since the 1970s, is decoupled from that of Sr and Cl. We propose that this process is linked to mantle source composition and is concomitant with changes in both volcanological and seismotectonic patterns of the volcano. There is no time evolution of DDF magma chemistry.

Description: Published

Description: 123-134

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

Description: JCR Journal

Description: .The estimation of CO2 storage capacity in deep geologic formations is a pre-requisite for an efficient and safe application of Carbon Capture and Storage (CCS). The evaluation of storage resources for CO2 geological sequestration is a challenging task and has been tackled using several static algorithms and dynamic methods, on a variety of scales ranging from country to site-specific. The purpose of this study is to present an up-to-date as well as an overall review of the storage capacity algorithms for oil and gas reservoirs, coal seams, and deep saline aquifers, including some worldwide estimation examples. Moreover, a practical application at local scale was also performed for an Italian deep reservoir located in the Po Plain (Northern Italy). The effective storage capacities were obtained applying the commonly established static methods, using both the theoretical and the geocellular volume of the reservoir. Although a conservative approach, this study demonstrates that the selected structure has favorable characteristics for CO2 geological storage and has the capacity to host the most part of the Po Plain CO2 emissions for several decades.

Description: Published

Description: 21-44

Description: 1TR. Georisorse

Description: The long-term warming of the ocean is a critical indicator of both the past and present state of the climate system. It also provides insights about the changes to come, owing to the persistence of both decadal variations and secular trends, which the ocean records extremely well (Hansen et al., 2011; IPCC, 2013; Rhein et al., 2013; Trenberth et al., 2016; Abram et al., 2019). It is well established that the emission of greenhouse gasses by human activities is mainly responsible for global warming since the industrial revolution (IPCC, 2013; Abram et al., 2019). The increased concentration of heat-trapping greenhouse gases in the atmosphere has interfered with natural energy flows. Currently there is an energy imbalance in the Earth’s climate system of almost 1 W m−2 (Trenberth et al., 2014; von Schuckmann et al., 2016, 2020a; Wijffels et al., 2016; Johnson et al., 2018; Cheng et al., 2019a; von Schuckmann et al., 2020a). Over 90% of this excess heat is absorbed by the oceans, leading to an increase of ocean heat content (OHC) and sea level rise, mainly through thermal expansion and melting of ice over land. These processes provide a useful means to quantify climate change. The first global OHC time series by Levitus et al. (2000) identified a robust long-term 0−3000 m ocean warming from 1948−98. Since then, many other analyses of global and regional OHC data have been performed. Here, we provide the first analysis of recent ocean heating, incorporating 2020 measurements through 2020 into our analysis.

Description: Published

Description: 523–530

Description: 4A. Oceanografia e clima

Description: JCR Journal

Description: We report on the geochemical and chronological characterization of a tephra layer, here called RdV-T1, recovered within a continental sequence at Riparo di Venere site in the Fucino Basin (central Italy). Textural, mineralogical, and detailed geochemical (major and trace elements on single glass shard) analyses indicate thatMt. Etna is the volcanic source. Radiocarbon dating of charred materials above and belowthis tephra layer result in 13,380±40 (16,260–15,920 cal yrs BP) and 13,620±40 (16,625–16,230 cal yrs BP) 14C years BP, respectively. This age points out that RdV-T1 tephra derives fromthe Late Pleistocene activity of the Ellittico caldera-forming phase of Mt. Etna that is significantly (up to 1750 yrs) younger than the Biancavilla Ignimbrites and upper Acireale fall, which are the last known events of this eruptive cycle. In addition, the RdV-T1 tephra geochemical signature is distinctwith respect to the Biancavilla Ignimbrites and upper Acireale fall. Therefore, the radiocarbon and geochemical data consistently indicate that the RdV-T1 tephra may represent an explosive event following the Biancavilla Ignimbritesand the upper Acireale fall not yet identified.

Description: Published

Description: 106992

Description: 1V. Storia eruttiva

Description: JCR Journal

Description: Mapping and luminescence aging of raised marine terraces and aeolian ridges along an ∼90 km coastal stretch in southwestern Sicily provide the first quantitative assessment of vertical tectonic deformation in this region, which spans the frontal part of an active thrust belt. We recognized a staircase of eleven terraces and nine related aeolian ridges. The elevation profile of terraces parallel to the coast shows a 〉90 km long bell-shaped pattern, onto which shorter-wavelength (∼10 km long) undulations are superimposed. Luminescence ages from terraced beach deposits and aeolian sediments constrain the position of paleoshorelines formed during MIS 5e, 7a and 7c, with a maximum uplift rate of ∼0.75 mm/a, and indicate a late Middle-Late Pleistocene (80–400 ka) age for the sequence of terraces. The elevation of Lower Pleistocene morpho-depositional markers points that uplift may have occurred at similar rates at the beginning of the Early Pleistocene, but almost zeroed between ∼1.5 and 0.4 Ma before the recent renewal. The uneven elevation of Middle-Upper Pleistocene paleoshorelines observed moving along the coast documents that uplift embeds both a regional and a local component. The regional, symmetric bell-shaped uplift is related to involvement in the thrust belt of thicker crustal portions of the northern African continental margin. The short-wavelength undulations represent the local component and correspond to actively growing bedrock folds. The present study contributes to unravel the different spatial and temporal scales of deformation processes at a collisional margin.

Description: Published

Description: 106812

Description: 2T. Deformazione crostale attiva

Description: JCR Journal

Description: Monitoring of the water column in the vicinity of offshore Carbon Capture and Storage (CCS) sites is needed to ensure site integrity and to protect the surrounding marine ecosystem. In this regard, the use of continuous, autonomous systems is considered greatly advantageous due to the costs and limitations of periodic, ship-based sampling campaigns. While various geochemical monitoring tools have been developed their elevated costs and complexities mean that typically only one unit can be deployed at a time, yielding single point temporal data but no spatial data. To address this the authors have developed low-cost pCO2 sensors (GasPro-pCO2) that are small, robust, stable, and which have a low power consumption, characteristics which allow for the deployment of numerous units to monitor the spatial-temporal distribution of pCO2, temperature, and water pressure in surface water environments. The present article details the results of three field deployments at the natural, CO2-leaking site near Panarea, Island. While the first consisted of 6 probes placed on the sea floor for a 2.5 month period, the other two involved the deployment of 20 GasPro units along a transect through the water column in the vicinity of active CO2 seeps over 2 – 4 days. Results show both transport and mixing processes and highlight the dynamic nature of the leakage-induced marine geochemical anomalies. Implications for monitoring programs as well as potential impacts are discussed.

Description: Published

Description: 3840 – 3847

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

Description: JCR Journal

Description: In this paper we summarize a number of risk pathway scenarios that are often claimed in literature as of priority for risk analyses in unconventional gas development. The resulting scenarios are structured in diagrams representing causal relationships between events. We argue that science is called to fill gaps regarding the main processes characterizing the involved events and defining the conditions under which their occurrence may be enhanced or inhibited. In this way, these scenarios can be more objectively parameterized, making their quantitative assessment a more feasible task and opening the way for the formulation of appropriate risk mitigation strategies.

Description: Published

Description: 116-125

Description: European Geosciences Union General Assembly 2017 (Vienna) EGU Division Energy, Resources & Environment (ERE)

Description: 1TR. Georisorse

Description: N/A or not JCR

Description: Analysis of natural and anthRopoGenic risks on Offshore platforms (ARGO) is a 3-years project, funded by the Italian Ministry of Economic Development. The project, coordinated by AMRA, a permanent Research Centre for the development of innovative technologies applied to environmental problems, aims at providing technical-support for the analysis of natural and anthropogenic risks on offshore oil-platforms. ARGO has developed methodologies for the probabilistic analysis of industrial accidents triggered by natural events (NA-TECH) on offshore platforms. The final analysis of the ARGO Project suggest a constant monitoring of exploitation activity, fluids re-injection and storage using high technology networks.

Description: Published

Description: 145–152

Description: European Geosciences Union General Assembly 2017, EGU (Vienna) European Geosciences Union General Assembly 2017, Division Energy, Resources & Environment

Description: 1TR. Georisorse

Description: N/A or not JCR

Description: Sicily hosts many natural manifestations that include thermal waters, gas discharges and mud volcanoes. Due to the significant geodynamic and geological differences, the fluid discharges along a NE-WS–oriented transect that run from the Peloritani Mts. to the Sciacca Plain shows a large variability in water and gas chemical and isotopic compositions. The studied waters are characterized by Ca-HCO3, Ca(Mg)-SO4, Ca-Cl and Na-Cl compositions produced by distinct geochemical processes such as water-rock-gas interactions, mixing between deep and shallow aquifers and seawater and direct and reverse ion exchanges. The gas chemistry is dominated by CO2 to the east and CO2-N2 to the west of the study area, whereas the central part shows mud volcanoes discharging CH4-rich gases. Water isotopes suggest that the thermal waters are fed by a meteoric recharge, although isotopic exchange processes between thermal fluids and host rocks at temperature 〉150°C are recognized. Accordingly, liquid geothermometry suggests equilibrium temperatures up to 220°C. The carbon in CO2 and helium isotopes of the emissions from the westernmost sector of Sicily indicate that these two gases consists of up to 40 % of a mantle component, the latter decreasing to the east down to 10% where CO2 of thermometamorphic origin dominates. Accordingly, conceptual models of the fluid circulation for the western, central and eastern sectors are proposed. The regional geothermal reservoir, hosted in carbonates in the western sector and locally outcropping, is of low to medium temperature. Higher temperature conditions (up to 200-220°C) are suggested by geothermometry and probably related to deeper levels of the system. Sicily can be regarded as a potentially suitable area for future investigations to evaluate specific activities aimed at exploiting the geothermal resource.

Description: Published

Description: 102120

Description: 9T. Geochimica dei fluidi applicata allo studio e al monitoraggio di aree sismiche

Description: JCR Journal

Description: composite stratigraphic section ranging from the Messinian to the Pliocene, recording the most important phases of the Messinian Salinity Crisis, is represented in the San Miguel de Salinas area (Bajo Segura basin, SE Spain). Detailed magnetostratigraphic and facies analyses and foraminifer and nannoplankton assemblage studies were carried out. Integration of the results has allowed the characterization of the pre-evaporitic (synthem Messinian I), syn-evaporitic (synthem Messinian II), and post-evaporitic phases (synthem Pliocene) from a paleoenvironmental and chronostratigraphic standpoint. The pre-evaporitic phase is late Messinian and records a shallowing-upward trend. The syn-evaporitic phase took place in chron C3r and is characterized by laminated marls with intercalated selenitic gypsum beds and sandstones. Variations in foraminifer and nannoplankton assemblages together with episodic gypsum precipitation record major changes in water salinity in a stressed marine environment. The pre- and syn-evaporitic phases are separated by the intra-Messinian unconformity, represented by an erosional surface related with a sea-level fall. After the evaporitic phase, a sea-level fall generates the end-Messinian unconformity, whose strongly erosional nature is evidenced by the deeply carved paleovalley of San Miguel de Salinas. The post-evaporitic phase begins in the earliest Pliocene and records the re-establishment of normal marine conditions in the basin. Since the San Miguel de Salinas composite section can be considered as a benchmark for the study of the evolution of marginal Mediterranean basins during the Messinian Salinity Crisis, the detailed characterization of these different phases is of great importance in understanding this event.

Description: Published

Description: 246-266

Description: 4A. Oceanografia e clima

Description: JCR Journal

Description: While processes involved in the protohistoric briquetage at Puntone (Tuscany, Italy) have been reconstructed in detail, the age of this industry remained uncertain since materials suited for traditional dating (14C dating on charcoal and typological dating of ceramics) were very scarce. We attempted to assess its age by radiocarbon dating organic matter and carbonates in strata that were directly linked to the industry. Microbial DNA and C isotope analyses showed that the organic matter is dominantly composed of labile organic matter, of which the age is coeval with the briquetage industry. Carbonates had a complex origin and were overall unsuited for radiocarbon dating: Shells in process residues exhibited a large, uncertain ‘marine reservoir effect’, hampering their use for dating the industry; the secondary carbonates in these residues had a quite varied composition, including much more recent carbonate that precipitated from infiltrated lateral run-off, as could be concluded from C and Sr isotope analyses. Dates found that were deemed reliable (c. 1000–100 cal BCE) show that this ancient industry, which started in the Late Bronze Age - Early Iron Age (1107–841 cal BCE), extended into the Roman Republican period and was contemporary with the saltern-based larger scale salt industry in Central Lazio.

Description: Published

Description: 103055

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

Description: JCR Journal

Description: A statistical analysis of Loss of Lock (LoL) over Brazil throughout the 24th solar cycle is performed. Four geodetic GPS dual-frequency (L1, L2) receivers, deployed at different geographic latitudes ranging from about 25° to 2° South in the eastern part of the country, are used to investigate the LoL dependence on time of the day, season, solar and geomagnetic activity. The results of the analysis show that LoL is most likely in the post-sunset hours during summer and equinox, especially within the southern crest of the Equatorial Ionospheric Anomaly (EIA), in a region between about 10°S and 25°S of geographic latitude, matching the typical behaviour of scintillation over Brazil. This is confirmed by the correlation found between the relative occurrence of LoL (LoL (%)) and the Rate Of TEC Index (ROTI), used as a proxy of scintillation index and calculated for each receivers along the entire period of investigation. The LoL (%) for given solar and geomagnetic indices show some correlation with increasing the severity of the index. This correlation is strongest in the area of the southern crest of the EIA, while there is little to no apparent impact closer to the equator, depending on the index. LoL (%) increases with increasing geomagnetic disturbances, varying between ~1% and ~10% for AE ranged between 400 and 1200 nT, and exceeding 3% when Dst is around −100 nT, both related to moderate-severely disturbed conditions.

Description: Published

Description: 219-225

Description: 2A. Fisica dell'alta atmosfera

Description: JCR Journal

Description: While mantle convection is a fundamental ingredient of geodynamics, the driving mechanism of plate tectonics remains elusive. Are plates driven only from the thermal cooling of the mantle or are there further astronomical forces acting on them? GPS measurements are now accurate enough that, on long baselines, both secular plate motions and periodic tidal displacements are visible. The now 〉20 year-long space geodesy record of plate motions allows a more accurate analysis of the contribution of the horizontal component of the body tide in shifting the lithosphere. We review the data and show that lithospheric plates retain a non-zero horizontal component of the solid Earth tidal waves and their speed correlates with tidal harmonics. High-frequency semidiurnal Earth's tides are likely contributing to plate motions, but their residuals are still within the error of the present accuracy of GNSS data. The low-frequency body tides rather show horizontal residuals equal to the relative motion among plates, proving the astronomical input on plate dynamics. Plates move faster with nu- tation cyclicities of 8.8 and 18.6 years that correlate to lunar apsides migration and nodal precession. The high- frequency body tides are mostly buffered by the high viscosity of the lithosphere and the underlying mantle, whereas low-frequency horizontal tidal oscillations are compatible with the relaxation time of the low-velocity zone and can westerly drag the lithosphere over the asthenospheric mantle. Variable angular velocities among plates are controlled by the viscosity anisotropies in the decoupling layer within the low-velocity zone. Tidal oscillations also correlate with the seismic release.

Description: Published

Description: 103179

Description: 1T. Struttura della Terra

Description: JCR Journal

Description: Several months of ambient seismic noise recordings are used for investigating the distribution of elastic properties in the Fucino Plain, one of the largest intermontane tectonic depressions of the Italian Apennine chain (Central Italy). The Plain is characterized by a low level of seismicity but the presence of several active faults makes it an Italian area of high seismic hazard. The most recent and strongest seismic event in Fucino Plain occurred in the 1915 (Avezzano earthquake) and it represents one of the most energetic events (Ms = 7.0) happened in central Apennines. Inter-stations Green’s functions are reconstructed by the cross-correlation of continuous ambient noise data recorded from twelve seismic velocimeters deployed around the Avezzano city, and organized in two different temporally sub-networks. The aim of cross-correlation analysis is to extract surface waves from Green’s functions for investigating the dispersive response of the structure. We analyzed the temporal stability of the cross-correlated signals that is used as an indicator of reliability of measurements and as criteria to select the Green’s functions to analyze

Description: Published

Description: 1173-1176

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

Description: Pyrite and organic matter closely coexist in some hydrothermally-altered gabbroic xenoliths from the Hyblean Plateau, Sicily. The representative sample consists of plagioclase, Fe-oxides, clinopyroxene, pyrite and minor amounts of many other minerals. Plagioclase displays incipient albitization, clinopyroxene is deeply corroded. Pyrite grains are widely replaced by spongy-textured magnetite, which locally hosts Ca-(and Fe-)sulfate micrograins and blebs of condensed organic matter. Whole-rock trace element distribution evidences that incompatible elements, particularly the fluid-mobile Ba, U and Pb, are significantly enriched with respect to N-MORB values. The mineralogical and geochemical characteristics of the sample, and its U-Pb zircon age of 216.9 ± 6.7 MA, conform to the xenolith-based viewpoint that the unexposed Hyblean basement is a relict of the Ionian Tethys lithospheric domain, mostly consisting of abyssal-type serpentinized peridotites with small gabbroic intrusions. Circulating hydrothermal fluids there favored the formation of hydrocarbons trough Fischer-Tropsch-type organic synthesis, giving also rise to sulfidization episodes. Subsequent variations in temperature and redox conditions of the system induced partial de-sulfidization, Fe-oxides precipitation and sulfate-forming reactions, also promoting poly-condensation and aromatization of the already-formed hydrocarbons. Here we show organic matter adhering to a crystal face of a microscopic pyrite grain. Pyrite surfaces, as abiotic analogues of enzymes, can adsorb and concentrate organic molecules, also acting as catalysts for a broad range of proto-biochemical reactions. The present data therefore may support established abiogenesis models suggesting that pyrite surfaces carried out primitive metabolic cycles in suitable environments of the early Earth, such as endolithic recesses in mafic rocks permeated by hydrothermal fluids.

Description: Published

Description: 19-47

Description: 4V. Processi pre-eruttivi

Description: JCR Journal

Description: Many long-term monitoring sites in Antarctic regions, which deploy ground-based stratospheric remote sensors and fly radiosondes or ozonesondes on balloons, supported the Airborne Polar Experiment in September and October 1999. Support consisted of supplying data to the campaign in real time, and in some cases by increasing the frequency of measurements during the campaign. The results will strengthen scientific conclusions from the airborne measurements. But results from these sites are allowing important scientific studies of new aspects of the ozone hole in their own right, because like the aircraft and its campaign, many sites traverse the vortex edge and are close to the largest source of lee waves, or measure infrequently observed trace gases such as HNO3. Examples of such studies are the behaviour and value of NO2 in midwinter, ozone filamentation with no apparent horizontal advection, the frequency and amplitude of gravity waves over the Antarctic Peninsula, mixing in the lowest stratosphere in Antarctic spring, the mechanism and frequency of HNO3 enhancement above the ozone peak in midwinter, and trends in UV dose in southern South America.

Description: Published

Description: 835–845

Description: 5A. Ricerche polari e paleoclima

Description: JCR Journal

Description: In the last decades, a growing number of works has increasingly focused on the study of thermal waters using the approach described by Giggenbach (1988). Based on the dependence on temperature of the equilibrium constants, the Na-K-Mg diagram is the combination of the Na-K and K-Mg geothermometers. The pristine approach proposed by Giggenbach (1988) included several constraints for its successful application. In spite of this, the Na-K-Mg diagram is often used out of the boundaries conditions of applicability. In order to promote a proper use of the diagram, a detailed description is given and several examples of mixing, dilution and concentration are discussed. The obtained findings highlight the need of cautiousness when using the diagram to estimate temperature of hydrothermal systems.

Description: Published

Description: 119577

Description: 4V. Processi pre-eruttivi

Description: 1TR. Georisorse

Description: JCR Journal

Description: The earthquake occured in Tohoku (Japan) in 2011 showed that no matter how outstanding is the model of the mitigation of natural hazard, an earthquake can always surprise any studied attempt to contain a tsunami. I report this extreme example to draw the reader attention on how strong should be the commitment of the society in producing the optimal conditions to face natural hazard. Every country has a peculiar social context. If in the past we considered this as a secondary aspect, now we are obliged to recognize that the social context is of main importance when promoting mitigation of natural hazard. In this occasion I would like to refer to my experience as an educator in my country. Italy is a country where it is difficult to promote a dialogue between the Institutions and the citizens. The dialogue is difficult also among the communities of engineers, geologists and politicians. There is still a great confusion on the attribution of tasks and a lot of problems of difficult solution are related to corruption. In this context, education can play a crucial role and should be intensively addressed to promote geo-awareness in the citizens. People should learn about the geological site where their houses are built and get all the info necessary to understand if it has been done according to the law. Only in this way citizens become an active agent in promoting those changes without which an efficacious mitigation of natural hazard is impossible.

Description: Published

Description: 85-88

Description: 3TM. Comunicazione

Description: Buildings close to each other can perform different behaviour despite its similar seismic vulnerability. This effect is mainly due to the local seismic response connected to the characteristics of the shallow soil layers, especially when we move away from the epicentral area and the near field motion reduces its importance among the total amount of shaking. In this paper we show some results of the microzonation project of the Avezzano municipality, a town located in the southwestern portion of the Abruzzi region, which experienced the severe effects of the January 13th, 1915 M 7.0 earthquake. Starting from a particularly detailed knowledge of the geological characteristics of outcropping lithologies and inferring the trend of subsoil geometries, we explored the role played by the near-surface geology in causing variability of the ground motion by analysing a large database of earthquakes and microtremor recordings acquired by temporary seismological networks using classical site-reference and non-reference spectral techniques. Based on the obtained results we can seismically characterize all the municipal territory not only in terms of fundamental resonance frequency, useful in drawing maps of seismic microzonation and design geological sections, but also of amplification factors helpful in verifying numerical modelling of seismic response as required by national microzonation guidelines. We have also found many criticisms that need a more detailed analysis in order to establish the cause of these anomalies.

Description: Published

Description: 1153-1157

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

Description: Vesiculation of crystallising magma can produce either a mobile vesicular magma or a rigid network of crystals containing vesicular liquid. Where partially crystallized rigid mush underlies less-crystallized magma, such as near the base of a lava flow or in the cumulus pile of a magma chamber, evolved interstitial melt and/or gas may escape into the main body of magma. The consequences of this may include contamination of the overlying liquid with gas and interstitial melt, or intrusion of diapirs of vesicular evolved liquids to form vertical vesicle cylinders and other segregation features found in many basaltic lava flows and sills. Analog experiments were used to investigate some of the phenomena that can arise during vesiculation within a crystal mush, which was simulated by pumping air through a porous plate that formed the floor of a container filled with a viscous liquid floored with a layer of glass beads. Experiments used either a single liquid or two stably stratified liquids with a liquid interface either coincident with the top of the porous layer of beads or slightly above the porous layer. For a range of liquid viscosities and air flow rates (vesiculation rates), individual bubbles emerged from the top of the porous layer of beads and carried a thin trail of interstitial liquid into the overlying liquid. The number of bubble trains leaving the surface of the porous bed increased with decreasing liquid viscosity and flow rate, and with increasing bead size (and, hence, with increasing permeability). Analog vesicle cylinders, composed of diapirs of bubbly interstitial liquid, were produced only when a layer of buoyant bubbly liquid lay above the surface of the porous layer. The relative size of the bubbles and constrictions within the porous layer are argued to control whether individual bubbles (leading to bubble trains) or vesicular liquid (leading to vesicle cylinders) leaves the porous layer and hence whether vesicle cylinders can form.

Description: Published

Description: 287–300

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

Description: JCR Journal

Description: Sub-surface operations for energy production such as gas storage, fluid reinjection or hydraulic fracking may modify the physical properties of the rocks, in particular the seismic velocity and the anelastic attenuation. The aim of the present study is to investigate, through a synthetic test, the possibility of using empirical ground-motion prediction equations (GMPEs) to observe the variations in the reservoir. In the synthetic test, we reproduce the expected seismic activity (in terms of rate, focal mechanisms, stress drop and the b value of the Gutenberg-Richter) and the variation of medium properties in terms of the quality factor Q induced by a fluid injection experiment. In practice, peak-ground velocity data of the simulated earthquakes during the field operations are used to update the coefficients of a reference GMPE in order to test whether the coefficients are able to capture the medium properties variation. The results of the test show that the coefficients of the GMPE vary during the simulated field operations revealing their sensitivity to the variation of the anelastic attenuation. The proposed approach is suggested as a promising tool that, if confirmed by real data analysis, could be used for monitoring and interpreting induced seismicity in addition to more conventional techniques.

Description: for Clean Energy) project, which received funding from the European Union’s Horizon 2020 research and innovation action, under grant agreement No 764810, and was partially funded by the PRIN Project MATISSE (Bando 2017, Prot. 20177EPPN2).

Description: Published

Description: 723–735

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

Description: JCR Journal

Description: In the last few decades, advanced monitoring networks have been extended to the main active volcanoes, providing warnings for variations in volcano dynamics. However, one of the main tasks of modern volcanology is the correct interpretation of surface-monitored signals in terms of magma transfer through the Earth's crust. In this frame, it is crucial to investigate decompression-induced magma degassing as it controls magma ascent towards the surface and, in case of eruption, the eruptive style and the atmospheric dispersal of tephra and gases. Understanding the degassing behaviour is particularly intriguing in the case of poorly explored evolved alkaline magmas. In fact, these melts frequently feed hazardous, highly explosive volcanoes (e.g., Campi Flegrei, Somma-Vesuvius, Colli Albani, Tambora, Azores and Canary Islands), despite their low viscosity that usually promotes effusive and/or weakly explosive eruptions. Decompression experiments, together with numerical models, are powerful tools to examine magma degassing behaviour and constrain field observations from natural eruptive products and monitoring signals. These approaches have been recently applied to evolved alkaline melts, yet numerous open questions remain. To cast new light on the degassing dynamics of evolved alkaline magmas, in this study we present new results from decompression experiments, as well as a critical review of previous experimental works. We achieved a comprehensive dataset of key petrological parameters (i.e., 3D textural data for bubbles and microlites using X-ray computed microtomography, glass volatile contents and nanolite occurrence) from experimental samples obtained through high temperature-high pressure isothermal decompression experiments on trachytic alkaline melts at super-liquidus temperature. We explored systematically a range of final pressures (from 200 to 25 MPa), decompression rates (from 0.01 to 1 MPa s−1), and volatile (H2O and CO2) contents. On these grounds, we integrated coherently literature data from decompression experiments on evolved alkaline (trachytic and phonolitic) melts under various conditions, with the aim to fully constrain the degassing mechanisms and timescales in these magmas. Finally, we simulated numerically the experimental conditions to evaluate strengths and weaknesses in decrypting degassing behaviour from field observations. Our results highlight that bubble formation in evolved alkaline melts is primarily controlled by the initial volatile (H2O and CO2) content during magma storage. In these melts, bubble nucleation needs low supersaturation pressures (≤ 50–112 MPa for homogeneous nucleation, ≤ 13–25 MPa for heterogeneous nucleation), resulting in high bubble number density (~ 1012–1016 m−3), efficient volatile exsolution and thus in severe rheological changes. Moreover, the bubble number density is amplified in CO2-rich melts (mole fraction XCO2 ≥ 0.5), in which continuous bubble nucleation predominates on growth. These conditions typically lead to highly explosive eruptions. However, moving towards slower decompression rates (≤ 10−1 MPa s−1) and H2O-rich melts, permeable outgassing and inertial fragmentation occur, promoting weakly explosive eruptions. Finally, our findings suggest that the exhaustion of CO2 at deep levels, and the consequent transition to a H2O-dominated degassing, can crucially enhance magma vesiculation and ascent. In a hazard perspective, these constraints allow to postulate that time-depth variations of unrest signals could be significantly weaker/shorter (e.g., minor gas emissions and short-term seismicity) during major eruptions than in small-scale events.

Description: Published

Description: 103402

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: 4V. Processi pre-eruttivi

Description: 5V. Processi eruttivi e post-eruttivi

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

Description: JCR Journal

Description: We present elemental maps and intra-crystal compositional profiles conducted on a representative clinopyroxene phenocryst from the 1974 eccentric lava flows at Mt. Etna volcano (Sicily, Italy). The eruption was fed by deep-seated and primitive magmas ascending through pathways bypassing the central volcanic conduits. These magmas show MgO and Cr contents higher (and REE + Y lower) than those characterizing younger and more evolved eruptions, albeit the bulk rock compositions of both primitive and more evolved products are invariably classified as trachybasalts in the TAS (total alkali vs. silica) diagram. Mafic recharge episodes are recorded by the complex textural features of the clinopyroxene, with a subrounded core enclosed within a concentrically zoned mantle. The core is enriched in Mg + Fe2++Na and depleted in Fe3++Ca relative to the mantle. The jadeite (Jd) component decreases from core to mantle and is counterbalanced by higher Ca-Tschermak (CaTs) contents, as the number of TAl cations in tetrahedral coordination increases. The Jd-rich core incorporates high proportions of rare earth elements and Y (REE + Y) and low concentrations of high field strength elements (HFSE) and transition elements (TE, such as Ni, Cr and Sc), whereas the opposite occurs for the CaTs-rich mantle. The decoupling of REE + Y and HFSE argues against simple changes in melt composition and indicates an additional mechanism driving trace element zonations. Thermobarometric calculations indicate that the early-formed Jd-rich core equilibrated with the host magma at mantle depths (750–950 MPa and 1190–1210 °C), whereas the later CaTs-rich mantle formed at shallower crustal levels (400–700 MPa and 1150–1180 °C) after magma recharge. Quantitative modeling of apparent cation partitioning between clinopyroxene and melt (Di) indicates that DHFSE increase from the Jd-rich core to the CaTs-rich mantle. In contrast, DREE+Y increase up to one order of magnitude at the Jd-rich core due to the enhanced stability of an Na0.5REE + Y0.5MgSiO6 end-member. We infer that compositional changes in clinopyroxene due to the different P-T conditions of the plumbing system may control the concentrations of REE + Y in residual melts derived after partial crystallization and differentiation of primitive magmas, such as those feeding the 1974 eccentric eruption. On this basis, we use DREE+Y measured across the core-mantle interface to constrain the geochemical evolution of recent 2000–2013 magmas at Mt. Etna volcano by Rayleigh fractional crystallization. Results indicate that magma dynamics proceed via a stepwise polybaric-polythermal process accounting for 1) crystallization of Jd-rich clinopyroxenes at high-P, high-T conditions, 2) upward migration of crystal-bearing magmas due to replenishment phenomena with input of fresh magmas and 3) crystallization of CaTs-rich clinopyroxene in low-P, low-T reservoirs. The resulting total amount (~40 vol%) of clinopyroxene fractionated agrees with geophysical data suggesting the presence of highly crystalline magmatic bodies at shallow to intermediate crustal levels below Mt. Etna.

Description: Published

Description: 105382

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

Description: JCR Journal

Description: Induced seismicity can be associated to the activity of fluid withdrawal and injection from/into the shallow crust (fracking, wastewater disposal into the deep crust, Enhanced Geothermal Systems technology, fluid extraction in oil fields and geothermal power plants). Long-term injection of large volumes of fluids is normally associated with induced seismicity, but the effect of withdrawal-reinjection in the same reservoir is less known, at least regarding its relation to simple injection. However, it is common experience worldwide that small (i.e. 10 MW or less) geothermal plants with withdrawal and re-injection of fluids in the same reservoir are mostly not associated with significant induced/triggered seismicity. This paper aims at understanding how to discriminate, on a numerical modelling basis, the seismogenic potential of withdrawal-reinjection with respect to injection only. With this aim, we analysed the induced pressure changes, the perturbed volumes of rocks and the potential for induced seismicity due to these operations. A set of simulations of injection or withdrawal-reinjection cycles, obtained by using the numerical code TOUGH2®, is applied to simple models of geothermal reservoirs, with varying permeability and lateral boundary constraints. For each permeability model, we then compare the time growth of perturbed volumes obtained with withdrawal-reinjection cycles to those obtained during simple injection, using the same flow rates. The size of perturbed volumes is then related to the maximum magnitude of induced/triggered seismicity, using models accredited in recent literature. Our results show that, for all models, withdrawal-reinjection is by far less critical than simple injection, because the perturbed volumes are remarkably smaller and remain constant over the simulated time, so minimizing the likelihood of interference with seismogenic faults. These results have significant implications for geothermal projects, and in the assessment of the potential risk related to fluid stimulation and induced seismicity.

Description: Published

Description: 101770

Description: 1TR. Georisorse

Description: JCR Journal

Description: Archaeoseismological evidence of a strong earthquake, which probably occurred a year before the 252 CE Mt. Etna eruption, has been uncovered at Santa Venera al Pozzo site, located near to Acireale, along the lower eastern flank of the volcano. The site, known for its remarkable and peculiar hydrothermal fluids emissions exploited for thermal uses since the Greek and Roman age, has been investigated through a multidisciplinary approach by integrating archaeoseismological observations with geological and geochemical surveys. Analysis of the observed damage and deformation at the site suggest a capable fault zone through the area. Geochemical and geological surveys were performed in and around the site and have revealed anomalies of soil CO2 efflux along an known active fault and likely also along some unmapped hidden faults. The chemical and isotopic composition of the emitted fluids suggests that these have not a volcanic origin, but they could be related with a deep tectonic system. The data presented in this paper suggest the occurrence of both exposed and hidden active faults in the area of Santa Venera al Pozzo, which could be linked to the seismic activity that damaged the historical site.

Description: Published

Description: 228544

Description: 2T. Deformazione crostale attiva

Description: JCR Journal

Description: We present a methodology for the selection of accelerometric time histories as input for dynamic response analyses over vast areas. The method is primarily intended for seismic microzonation studies and regional probabilistic seismic hazard assessments that account for site effects. It is also suitable for structural response analyses if one would like to use a fixed set of ground motion records for analyzing multiple structures with different (or unknown) periods. The proposed procedure takes advantage of unsupervised machine learning techniques to identify zones (i.e., groups of sites) with homogeneous seismic hazard, for which the same set of earthquake recordings can be reasonably used in the numerical simulations. The procedure consists of three steps: (1) data-driven cluster analysis to identify groups of sites with comparable seismic hazard levels for a specified mean return period (MRP); (2) for each zone, definition of a single, reference uniform hazard spectrum (UHS) corresponding to the MRP of interest; (3) selection of a set of accelerometric recordings that are consistent with the magnitude-distance scenarios contributing to the hazard of each zone, and meet the spectrum-compatibility requirement with respect to the reference UHS. An application of the procedure in the Po Plain (Northern Italy) is described in detail.

Description: Published

Description: 2985–3004

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

Description: JCR Journal

Description: Recently, an earthquake sequence formed by a series of subsequences characterized by large earthquakes (three events M ≥ 6.0 and five events M ≥ 5.0) occurred in the Central Apennines in 6–7 months during 2016–2017. Several studies interpreted this cascading type of earthquake occurrence as associated with fluid movements through an interconnected network of cracks around the active faults that triggered the subsequences in different time and location. In the present study we aim to verify if the presence of fluids is confirmed by the pattern of seismic wave attenuation. To do so we separately estimate the space-averaged parameters intrinsic Qi−1 and scattering Qs−1, proportional to the correspondent attenuation parameters, by applying a modified Multiple Lapse Time Window Analysis (MLTWA), in order to establish reference background values for the study region. MLTWA measures the decay of S-wave energy with distance and lapse time and fit it to the Energy Transport Equation solution for scattering, yielding the seismic albedo, B0 = Qs−1/Qt−1 and the extinction Length, Le,∝Qt−1 parameters as a function of frequency. The knowledge of the separated attenuation parameters allows determining which process of seismic energy dissipation dominates in the region. In the present study B0 results to be around0.6 (at 1.5 Hz) and decreases with increasing frequency down to 0.2 indicating that the attenuation of the seismic energy carried by S-wave is controlled by intrinsic dissipation rather than by scattering. Moreover, the intrinsic attenuation is frequency dependent (f −0.9 for the uniform model and f −0.4 for the crust/Moho model). This behavior well matches with the presence of fluids in the faults and fracture zones in the central Apennines, in agreement with results from other independent studies in the region. Finally, a comparison among the attenuation parameters estimated for this area and those measured in several areas of Italy and other parts of the world is presented together with a discussion on the comparison between the present MLTWA attenuation estimates and homologous results obtained for the same area with different approaches.

Description: Published

Description: 106498

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

Description: JCR Journal

Description: Nowadays, electrical resistivity tomography (ERT) is able to furnish a global reconstruction of the main features of buried structures at a shallow scale, in a faster and cost-effective manner. The use of a controlled source makes ERT less sensitive to noise with respect to other geophysical methodologies based on natural sources, such as magnetotelluric. During field practice, the depth of exploration is limited by the relative distances between the source and receiver dipoles. The latest generation resistivimeters favor the simultaneous recording of signals in correspondence with multiple and physically separated receivers. These characteristics concur towards a more profitable application of ERT imaging in the case of deeper targets distributed within harsh or densely inhabited large areas. At the same time, the ease of placing a good number of receivers far from the electric sources enhances the need of tools apt for extracting weaker signals from background noise of both natural and anthropic nature. For this purpose, the use of the well-known method, i.e., principal component analysis (PCA) as a filtering tool is tested on the geoelectrical time series acquired in the Mt. Vesuvius area (Naples, Italy). A field and a test dataset have been derived from such recordings and subsequently processed through an original procedure based on PCA. Subsequently, the results have been compared with the ones obtained using more typical estimators, such as stacking or frequency filtering, thus evaluating the usefulness of PCA in the processing of the geoelectrical time series. A good estimate of the said parameters can also be obtained in the case of source-to-receiver distance of more than 5 km.

Description: Published

Description: 104038

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

Description: JCR Journal

Description: A high resolution set-up of a z-level ocean model has been implemented in the Adriatic Sea to investigate the impact of the Levantine Intermediate Water on the Adriatic Sea circulation and dense water formation. The period under investigation starts at the beginning of 2000 and ends at the end 2007. A twin experiment is performed in which the southern boundary conditions are derived from two different operational systems in the Mediterranean Sea. It is shown that the quantity and the characteristics of the Levantine Intermediate Water in the Mediterranean model introduced at the southern boundary may significantly impact the amount of the dense water formed in the Southern Adriatic and the accuracy of the model simulation even in the Northern Adriatic.

Description: Published

Description: 253-263

Description: 4A. Oceanografia e clima

Description: JCR Journal

Description: The Fucino lacustrine basin in central Italy is a large flat area mostly devoted to agriculture, with urbanization along the perimeter of the ancient lake. In 1915 a strong earthquake struck the area (Mw 7.0), producing large damages and geological effects, including surface faulting, ground failures and liquefaction. A channel excavated in the lacustrine sediments exposed ground failure, with dykes of fine-grained sediment that we interpret as the result of earthquake-induced liquefaction. We present the results of a multidisciplinary work aimed at characterizing in detail the geology of the buried stratigraphic succession, its susceptibility to liquefaction and the likely source of the fine-grained liquefied material. The succession down to 20 m deep is formed by fine-grained sediments younger than ~170–180 kyrs (mostly Late Pleistocene - Holocene), prevailingly silt or silt-clay mixtures. The geological field analysis indicates that the dykes are filled by prevailing silt, liquefied and transported by upward-directed flow of short duration, as for earthquake-induced liquefaction. Tilting and lateral spreading accompanied the process. The overall liquefaction potential derived from the “simplified methods” is high. Correlations of X-Ray Powder Diffraction mineralogy of samples from drilling cores with those from dykes allowed us to identify the most likely source layer filling dykes, corresponding to a silt layer at 7–8 m depths. This layer and the dykes lack illite and montmorillonite clay particles. These results contribute to improve studies of liquefactions in sediments that differ from typical liquefiable loose sands. They have also implications for microzonation studies. Most samples show grain-size curves that do not fit within the field of potentially liquefiable soils, suggesting that criteria based on grain-size can be poorly significant in seismic microzonation studies of recent (Late Pleistocene-Holocene) lacustrine, fine-grained successions.

Description: Published

Description: 105621

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

Description: JCR Journal

Description: Multiparametric observations integrate signals from different techniques into a unified time and space frame, and are key in understanding and monitoring the evolution of volcanic systems and eruptive activity. Mafic explosive eruptions, with a relatively high frequency of occurrence and low intensity, allow for detailed multiparametric observations at a relatively close distance. Typically, pyroclast ejection in these eruptions is not steady, but is characterized by the occurrence of ejection pulses, linked to pressure release events and featuring a characteristic nonlinear decay of pyroclasts exit velocity. Pulse frequency, duration, and exit velocity define the dominant eruptive style, function of the volume and pressure of the released gas, conduit size, and magma rheological-mechanical properties. No important differences in pressure and velocity divide eruptions with different magnitude and style. Ejection pulses influence the geophysical signature, plume development, and the emplacement of ballistic volcanic projectiles at eruptions from Strombolian to Vulcanian styles.

Description: Published

Description: 379-411

Description: 4V. Processi pre-eruttivi

Description: 5V. Processi eruttivi e post-eruttivi

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

Description: Abstract There is evidence that the tsunami as a destructive natural phenomenon has been known since antiquity. Although rare, tsunamis can affect densely populated areas, provoking heavy destruction and extensive casualties. A deep knowledge of their characteristics, such as generation mechanism, propagation, and effects is fundamental to assess the tsunami hazard of a region. Therefore, as for all natural events, also for tsunamis the observation and analysis of past occurrences is the basis of understanding the phenomenon. The study of historical tsunami records is the first step for hazard evaluation and for the calibration and validation of numerical models aimed at tsunami mitigation. This work wishes to emphasize the importance and limitations of historical data and catalogue in tsunami hazard assessment and to underline problems related to the critical interpretation and evaluation of historical sources.

Description: Published

Description: 21-31

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

Description: The Onano eruption (~ 0.17 Ma) is the second to last caldera-forming eruption of the Latera volcano, in the northernmost sector of the Roman Comagmatic Province (Latium, Italy). The stratigraphic sequence, from base to top, includes ash and pumice-rich flow deposits, spatter-rich flow deposits and lag breccias associated with ash-rich flow deposits. By combin-ing major and trace element compositions of the bulk rocks, matrix glasses and minerals of juvenile components from the different depositional units, we reconstruct the pre-eruptive evolution of the magma chamber and the syn-eruptive magma dynamics. Juvenile clasts with heterogeneous glass composition and/or mineral assemblage are a ubiquitous feature of the Onano eruption. The products cover a large compositional range from phonotephrite to phonolite. They are crystal poor, with felsic paragenesis associated to Mg-rich olivine (Fo82–90) and diopside (Fs4–7), these last not in equilibrium with the erupted melts. The mafic mineral assemblage suggests that the pre-eruption magma reservoir was periodically perturbed by the arrival of a primitive magma carrying on Mg-rich minerals and/or remobilizing a mafic crystal mush at the bottom of the reservoir. According to the results obtained from both rhyolite-MELTS and Rayleigh crystal fractionation modeling, we infer that the system evolved from phonotephrite to phonolite both via crystal fractionation and magma mixing between the two end members. Crystallization mostly proceeded at the wall of the reservoir, while magma mixing in the middle zones of the chamber generated the intermediate tephriphonolitic melts. The pre-eruptive chemical zoning was disrupted during the course of the eruption due to the simultaneous withdrawal of magma from different portions of the reservoir. During the first phase of the eruption, high-silica tephriphonolitic to phonolitic melts, residing in the upper part of the reservoir, were emitted with less involvement of the deeper phonotephrite. Phonotephritic magmas, with only a minor contribution of evolved melts, were later erupted as spatter-rich pyroclastic flows that preceded the main caldera collapse. During the caldera collapse, the whole reservoir was involved, leading to extensive and intimate syn-eruption mingling of the different melts. A comparison between the Onano eruption and other eruptions of the Italian high potassic volcanism provides new insights into the evolution of the Roman Comagmatic Province magmas and their eruptive processes.

Description: FISR 2016, Project “Centro di studio e monitoraggio dei rischi naturali dell’Italia Centrale.

Description: Published

Description: 84

Description: 4V. Processi pre-eruttivi

Description: JCR Journal

Description: The Pietra del Pertusillo freshwater reservoir is a major artificial lake of environmental, biological, and ecological importance located in the Basilicata region, southern Italy. The reservoir arch-gravity dam was completed in 1963 for producing hydroelectric energy and providing water for human use, and nearby there are potential sources of anthropogenic pollution such as urban and industrial activities. For the first time, the minero-chemistry of the lake and fluvio-lacustrine sediments of the reservoir have been evaluated to assess the environmental quality. Moreover, the composition of fluvial sediments derived from the peri-lacual zone of the reservoir and of local outcropping bedrock were also studied to understand the factors affecting the behavior of elements in the freshwater reservoir, with particular attention paid to heavy metals. In Italy, specific regulatory values concerning the element threshold concentration for lake and river sediments do not exist, and for this reason, soil threshold values are considered the standard for sediments of internal waters. The evaluation of the environmental quality of reservoir sediments has been performed using enrichment factors obtained with respect to the average composition of a reconstructed local upper continental crust. We suggest this method as an innovative standard in similar conditions worldwide. In the studied reservoir sediments, the trace elements that may be of some environmental concern are Cr, Cu, Zn, As, and Pb although, at this stage, the distribution of these elements appears to be mostly driven by geogenic processes. However, within the frame of the assessment and the preservation of the quality of aquatic environments, particular attention has to be paid to As (which shows median value of 10 ppm, reaching a maximum value of 26 ppm in Quaternary sediments), constantly enriched in the lacustrine samples and especially in the fine-grained fraction (median = 8.5 ppm).

Description: Published

Description: 4857–4878

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

Description: JCR Journal

Description: The explosive eruptions that occurred between nineteenth and twentieth centuries produced a fundamental cultural impact on the development of Volcanology. Pyroclastic products and ignimbrites features start to be at the base of an international debate. Various descriptions of explosive eruptions, and a new terminology of their products, such as nuée ardente and ignimbrite, were presented and extensively discussed in the framework of the International Association of Volcanology conferences held in 1961 at Catania and in 1963 at Tokyo. Ignimbrite deposits are frst assimilated to welded tufs. That attention to explosive volcanism of the frst half of the twentieth century was the context in which has matured the Alfred Rittmann model of rheoignimbrite as welded ignimbrite showing secondary fowage structures. This term introduced by Rittmann in 1958, and shared by Giorgio Marinelli in 1961, was intended to describe the extensive sheet of acidic vitrophyric volcanic rocks of Monte Amiata volcano, interpreted as lava fows by all previous authors. Rheomorphic ignimbrites, in the Rittmann model, have features that strongly diferentiate them from normal ignimbrites and that are very similar to what shown by acidic lava fows, as fuidal structures and wrinkles. The concept of rheomorphic ignimbrite is still in use into the volcanological literature, even if not for the Monte Amiata volcanics, nowadays defnitively considered to be lava fows and domes. However, the Rittmann and Marinelli authoritative assumptions inhibited, up to present times, new volcanological interpretation of Monte Amiata acidic lavas.

Description: Published

Description: 539–561

Description: 1V. Storia eruttiva

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

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

Description: JCR Journal

Description: The dichotomy between explosive volcanic eruptions, which produce pyroclasts, and effusive eruptions, which produce lava, is defined by the presence or absence of fragmentation during magma ascent. For lava fountains the distinction is unclear, since the liquid phase in the rising magma may remain continuous to the vent, fragment in the fountain, then re-weld on deposition to feed rheomorphic lava flows. Here we use a numerical model to constrain the controls on basaltic eruption style, using Kilauea and Etna as case studies. Based on our results, we propose that lava fountaining is a distinct style, separate from effusive and explosive eruption styles, that is produced when magma ascends rapidly and fragments above the vent, rather than within the conduit. Sensitivity analyses of Kilauea and Etna case studies show that high lava fountains (〉50 m high) occur when the Reynolds number of the bubbly magma is greater than ∼0.1, the bulk viscosity is less than 10^6, and the gas is well-coupled to the melt. Explosive eruptions (Plinian and sub-Plinian) are predicted over a wide region of parameter space for higher viscosity basalts, typical of Etna, but over a much narrower region of parameter space for lower viscosity basalts, typical of Kilauea. Numerical results show also that the magma that feeds high lava fountains ascends more rapidly than the magma that feeds explosive eruptions, owing to its lower viscosity. For the Kilauea case study, waning ascent velocity is predicted to produce a progressive evolution from high to weak fountaining, to ultimate effusion; whereas for the Etna case study, small changes in parameter values lead to transitions to and from explosive activity, suggesting that eruption transitions may occur with little warning.

Description: RCUK NERC DisEqm project

Description: Published

Description: 116658

Description: 5V. Processi eruttivi e post-eruttivi

Description: JCR Journal

Description: Groundwater resources constitute the main source of clean fresh water for domestic use and it is essential for food production in the agricultural sector. Groundwater has a vital role for water supply in the Campanian Plain in Italy and hence a future sustainability of the resource is essential for the region. In the current paper novel data mining algorithms including Gaussian Process (GP) were used in a large groundwater quality database to predict nitrate (contaminant) and strontium (potential future increasing) concentrations in groundwater. The results were compared with M5P, random forest (RF) and random tree (RT) algorithms as a benchmark to test the robustness of the modeling process. The dataset includes 246 groundwater quality samples originating from different wells, municipals and agricultural. It was divided for the modeling process into two subgroups by using the 10-fold cross validation technique including 173 samples for model building (training dataset) and 73 samples for model validation (testing dataset). Different water quality variables including T, pH, EC, HCO3-, F-, Cl-, SO42-, Na+, K+, Mg2+, and Ca2+ have been used as an input to the models. At first stage, different input combinations have been constructed based on correlation coefficient and thus the optimal combination was chosen for the modeling phase. Different quantitative criteria alongside with visual comparison approach have been used for evaluating the modeling capability. Results revealed that to obtain reliable results also variables with low correlation should be considered as an input to the models together with those variables showing high correlation coefficients. According to the model evaluation criteria, GP algorithm outperforms all the other models in predicting both nitrate and strontium concentrations followed by RF, M5P and RT, respectively. Result also revealed that model's structure together with the accuracy and structure of the data can have a relevant impact on the model's results.

Description: Published

Description: 136836

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

Description: JCR Journal

Description: It has long since been noted that minor element (Me) partitioning into biogenic carbonates is sometimes different from Me partitioning into inorganically precipitated carbonates. The prime example is the partitioning coefficient, which might be lower or even higher than the one of inorganically precipitated carbonate. Such a difference is usually termed “vital effect” and is seen as indicative of a biologically modified minor element partitioning. Over the last three decades interest in conceptual biomineralization models compatible with minor element and isotope fractionation has been steadily increasing. However, inferring features of a biomineralization mechanism from Me partitioning is complicated, because not all partitioning coefficients show vital effects in every calcium carbonate producing organism. Moreover, the partitioning coefficient is not the only aspect of Me partitioning. Other aspects include polymorph specificity and rate dependence. Patellogastropod limpets are ideally suited for analysing Me partitioning in terms of biomineralization models, because they feature both aragonitic and calcitic shell parts, so that polymorph specificity can be tested. In this study, polymorph-specific partitioning of the minor elements Mg, Li, B, Sr, and U into shells of the patellogastropod limpet Patella caerulea from within and outside a CO2 vent site at Ischia (Italy) was investigated by means of LA-ICP-MS. The partitioning coefficients of U, B, Mg, and Sr (in aragonite) differed from the respective inorganic ones, while the partitioning coefficients of Li and Sr (in calcite) fell within the range of published values for inorganically precipitated carbonates. Polymorph specificity of Me partitioning was explicable in terms of inorganic precipitation in the case of Sr and Mg, but not Li and B. Seawater carbon chemistry did not have the effect on B partitioning that was expected on the basis of data on inorganic precipitates and foraminifera. Carbon chemistry did affect Mg (in aragonite) and Li, but only the effect on Mg was explicable in terms of calcification rate. On the one hand, these results show that Me partitioning in P. caerulea is incompatible with a direct precipitation of shell calcium carbonate from the extrapallial fluid. On the other hand, our results are compatible with precipitation from a microenvironment formed by the mantle. Such a microenvironment was proposed based on data other than Me partitioning. This is the first study which systematically employs a multi-element, multi-aspect approach to test the compatibility of Me partitioning with different conceptual biomineralization models.

Description: Published

Description: 218-229

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

Description: JCR Journal

Description: Deterioration of groundwater quality due to the introduction of pollutants from natural and anthropic sources has become a major environmental issue. We tested three methodologies in assessing groundwater quality and intrinsic aquifer vulnerability in the Agro-Aversano area (Southern Italy). A geographic information system (GIS)-based groundwater quality index (GQI) was realized to assess groundwater quality for drinking and irrigation use and, in parallel, standard SINTACS was applied to evaluate the intrinsic vulnerability of the aquifer. Nitrate concentrations and sodium absorption ratio (SAR) in groundwater samples were used to verify the reliability of vulnerability data. GQI analysis pointed to a general poor quality of groundwater both for drinking and irrigation use, especially in sub-urban areas. The spatial pattern of water quality from GQI analysis was positively related to nitrate and fluoride concentrations for drinking use and to bicarbonate and sodium concentrations for irrigation use, whose levels exceeded the WHO and FAO recommended thresholds, respectively. Standard SINTACS was found to be inadequate for describing the aquifer state, its results showing no correlation with nitrate concentration or SAR. Because of this inconsistency, we tested a novel approach combining GQI with SINTACS analysis. Results showed positive correlation with nitrate (r = 0.63) and SAR (r = 0.64) contents, thus pointing to combined SINTACS-GQI as a more reliable approach than standard methodologies.

Description: Published

Description: 768

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

Description: JCR Journal

Description: Groundwater resources are the main supply of freshwater for human activities. However, in the last fifty years aquifers have become more susceptible to chemical pollution due to human activities. The concept of groundwater vulnerability constitutes a worldwide accepted tool for water protection and planning. However, the existing methods and modified versions do not account for all the hydrogeochemical processes that drive anthropogenic pollution. The hydrogeochemical processes occurring within an aquifer can be determined using multivariate statistical analysis. In this study a specific vulnerability method named SVAP (Specific Vulnerability to Anthropogenic Pollution) is proposed. The index is based on seven quantitative parameters: depth to groundwater, recharge, nitrate losses, hydraulic resistance of the vadose zone, aquifer thickness, hydraulic conductivity of the aquifer, and slope. Weights of anthropogenic factors were determined by factor analysis and used to validate the SVAP methodology. The parameters' classification was selected according to the highest Pearson's correlation coefficient with factor weights and then grouped via a linear combination. The new index was applied in two watersheds: the Florina basin (Greece) and the Garigliano River basin (Italy), both of which possess complex hydrogeochemical regimes. The main hydrogeochemical processes acting in the study areas were identified via factor analysis, which revealed that the anthropogenic pollution in both sites was due mainly to chemical fertilizers and manure. Verification of the SVAP method produced correlation coefficients with nitrate concentrations of 0.75 and 0.62 in Florina and Garigliano, respectively. The proposed SVAP method is more reliable and flexible than standard vulnerability assessment methods and can be easily adapted for complex aquifers.

Description: Published

Description: 115386

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

Description: JCR Journal

Description: In this study, the results of a continuous monitoring of (i) CO2 fluxes, and (ii) CO2 and CH4 concentrations and carbon isotopic ratios (δ13C-CO2 and δ13C-CH4) in air, carried out from 7 to 21 July 2017 and from October 10 to December 15, 2017 in the city centre of Florence, are presented. The measurements were performed from the roof of the historical building of the Ximenes Observatory. CO2 flux data revealed that the metropolitan area acted as a net source of CO2 during the whole observation period. According to the Keeling plot analysis, anthropogenic contributions to atmospheric CO2 were mainly represented by vehicular traffic (about 30%) and natural gas combustion (about 70%), the latter contributing 7 times more in December than in July. Moreover, the measured CO2 fluxes were about 80% higher in fall than in summer, confirming that domestic heating based on natural gas is the dominant CO2 emitting source in the municipality of Florence. Even though the continuous monitoring revealed a shift in the δ13C-CO2 values related to photosynthetic uptake of atmospheric CO2, the isotopic effect induced by plant activity was restricted to few hours in October and, to a lesser extent, in November. This suggests that urban planning policies should be devoted to massively increase green infrastructures in the metropolitan area in order to counterbalance anthropogenic emissions. During fall, the atmospheric CH4 concentrations were sensibly higher with respect to those recorded in summer, whilst the δ13C-CH4 values shifted towards heavier values. The Keeling plot analysis suggested that urban CH4 emissions were largely related to fugitive emissions from the natural gas distribution pipeline network. On the other hand, δ13C-CH4 monitoring allowed to recognize vehicular traffic as a minor CH4 emitting source.

Description: Published

Description: 134245

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

Description: JCR Journal

Description: Viruses of hyperthermophilic archaea represent one of the least understood parts of the virosphere, showing little genomic and morphological similarity to viruses of bacteria or eukaryotes. Here, we investigated virus diversity in the active sulfurous fields of the Campi Flegrei volcano in Pozzuoli, Italy. Virus-like particles displaying eight different morphotypes, including lemon-shaped, droplet-shaped and bottle-shaped virions, were observed and five new archaeal viruses proposed to belong to families Rudiviridae, Globuloviridae and Tristromaviridae were isolated and characterized. Two of these viruses infect neutrophilic hyperthermophiles of the genus Pyrobaculum, whereas the remaining three have rod-shaped virions typical of the family Rudiviridae and infect acidophilic hyperthermophiles belonging to three different genera of the order Sulfolobales, namely, Saccharolobus, Acidianus, and Metallosphaera. Notably, Metallosphaera rod-shaped virus 1 is the first rudivirus isolated on Metallosphaera species. Phylogenomic analysis of the newly isolated and previously sequenced rudiviruses revealed a clear biogeographic pattern, with all Italian rudiviruses forming a monophyletic clade, suggesting geographical structuring of virus communities in extreme geothermal environments. Analysis of the CRISPR spacers suggests that isolated rudiviruses have experienced recent host switching across the genus boundary, potentially to escape the targeting by CRISPR-Cas immunity systems. Finally, we propose a revised classification of the Rudiviridae family, with the establishment of six new genera. Collectively, our results further show that high-temperature continental hydrothermal systems harbor a highly diverse virome and shed light on the evolution of archaeal viruses.

Description: Published

Description: 1821–1833

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

Description: 1TR. Georisorse

Description: JCR Journal

Description: The Late Quaternary benthic foraminiferal and ostracod assemblages from two continuous cores drilled in the Port of Salerno were studied to define their relationship with geochemical characteristics of the sediments and with the palaeoenvironmental evolution. The succession, ranging from Late Pleistocene to the 20th century, recorded the transition from a marine coastal environment under natural conditions to a depositional context affected by anthropogenic influence. In the lower part of the sequence, ecological and sedimentary changes were linked to sea-level changes due to Late Quaternary climatic phases, as well as to volcanic events such as the Campanian Ignimbrite eruption, represented by levels with high metal (Fe, Mn, Pb, Zn) concentrations, possibly leading to low pH phases. Later human activities, such as the construction of harbour facilities in the 18th century and the industrial development in the 19th century, influenced environmental variations, as shown in the upper part of the succession. High levels of heavy metal concentrations (Co, Cu, Fe, Pb, V) recorded in layers deposited in the 1800s suggest the presence of a pollution event which could be linked to manufacturing activities and might have occurred during the first part of the 19th century. Calcareous meiofaunal assemblages showed high diversity values, probably due to the occurrence of "rare short lived" species in an unstable environment. Assemblages were dominated by the foraminiferal species Ammonia aberdoveyensis and Haynesina depressula, and by the ostracods Pontocythere turbida and Semicytherura sulcata, which are considered as possibly stress-tolerant species.

Description: Published

Description: 101498

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

Description: JCR Journal

Description: We present a review of the geomorphology of the Tyrrhenian Sea coast of central Italy integrated by a novel structural-geomorphological study coupled with statistical analysis of topographic culminations and comparison with a Digital Elevation Model, aimed at reconstructing a suite of paleo-surfaces corresponding to remnant portions of marine terraces. We performed geochronological, sedimentological, micromorphological and mineralogical investigations on the deposits forming the different paleo-surfaces between Civitavecchia and Anzio towns, in order to provide chronostratigraphical, paleogeographical and paleoenvironmental constraints. Using the newly achieved dataset we correlate these paleo-surfaces with the coastal terraces formed during past sea-level highstands, as recognized by previous studies, and we refine their correlation with the Marine Isotope Stage (MIS) timescale. In particular, we have extended our geomorphological analyses landward in the area between the Tiber River mouth and Anzio, in order to include the oldest paleo-surface developed above the deposits of the last large explosive eruption at 365 ± 4 ka in the Colli Albani Volcanic District. Results of this study allow us to recognize a set of higher paleo-surfaces at elevation ranging 108 thought 71 m a.s.l., which we interpret as one tectonically displaced, widespread coastal terrace originated during the MIS 9.1 highstand. We correlate the previously identified paleo-surfaces of 66–62 m a.s.l. and 56–52 m a.s.l. with the equivalent coastal terraces developed during the sea-level highstands of sub-stages 7.5 and 7.3/7.1. Moreover, based on data from literature on relative elevation of maximum sea level during the highstands of MIS 11 through MIS 5.1, we assess the regional uplift and the concurrent tectonic displacements that have occurred since 900 ka in this area.

Description: Published

Description: 106843

Description: 2T. Deformazione crostale attiva

Description: JCR Journal

Description: CCS communication has proven a tough challenge, particularly for the difficulty in raising interest for the technology, which is still unknown to the majority of the population, and for the complexity of conveying information about its potential for reducing emissions. In this paper, we present a research based effort for bringing CCS nearer to people, through visual material developed taking into account emotional needs related to the technology. The production of a short introductory film on CCS is illustrated and its testing with a sample of 700 high school students.

Description: Published

Description: 7367 – 7378

Description: 2TM. Divulgazione Scientifica

Description: JCR Journal

Description: National Italian funding has recently been allocated for the construction of a 350 MWe coal-fired power plant / CCS demonstration plant in the Sulcis area of SW Sardinia, Italy. In addition, the recently approved EC-funded ENOS project (ENabling Onshore CO2 Storage in Europe) will use the Sulcis site as one of its main field research laboratories. Site characterization is already ongoing, and work has begun to design gas injection experiments at 100-200 m depth in a fault. This article gives an overview of results to date and plans for the future from the Sapienza University of Rome research group.

Description: Published

Description: 2742 – 2747

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

Description: JCR Journal

Description: Continuous monitoring has been carried out at a fluvial flood-plain site near Rome for over a year. There is a mix of biogenic CO2 and deep geogenic CO2 at the site at relatively low concentrations and fluxes compared with other natural CO2 seepage sites studied previously. Factors such as temperature and soil moisture clearly affect the CO2 concentration and flux and seasonal and diurnal influences are apparent. Statistical approaches are being used to try to define these relationships and separate out the two gas components, which would be necessary in any quantification of leakage from CO2 storage.

Description: Published

Description: 3824 – 3831

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

Description: JCR Journal

Description: The Sulcis Basin is an area situated in SW Sardinia (Italy) and is a potential site for the development of CCS in Italy. This paper illustrates the preliminary results of geological characterization of fractured carbonate reservoir (Miliolitico Fm.) and the sealing sequence, composed by clay, marl, and volcanic rocks, with a total thickness of more than 900 m. To characterize the reservoir-caprock system an extensive structural-geological survey at the outcrop was conducted. It was also performed a study of the geochemical monitoring, to define the baseline conditions, measuring CO2 concentrations and flux in the study site.

Description: Published

Description: 549–555

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

Description: JCR Journal

Description: 3D geological models from multi-source data (cross-sections, geological maps, borehole logs and outcrops) are a critical tool to improve the interpretation of the spatial organization of subsurface structures that are not directly accessible. In this paper, we reconstruct the main geological structures and surfaces in three dimensions through the interpolation of closely and regularly spaced 2D seismic sections, constrained by wells data and surface geology. The methodology was applied in the Marche–Abruzzi sector of the Periadriatic basin, where the more external part of the Apennines fold-and-thrust belt is mostly buried under a syn- and post-orogenic, Plio–Pleistocene, siliciclastic sequence. The 3D model allowed us to correlate the main thrust fronts and related anticlines along strike, revealing a general ramp – flat – ramp trajectory characterizing the main structural trends. This geometric organization influences the sequence of thrust-system propagation and characterizes the evolution of syntectonic basins. The obtained 3D model points out several variation occurring along strike: i) main trends geometric relationships; ii) deformation chronology and iii) displacement distribution. In the northern sector, higher displacement and structural elevation are reached out by the Nereto–Bellante structure, whereas in the southern sector the Villadegna–Costiera Structure is the prevalent. All structures show a diachronic thrusts activity along strike, younger toward the north.

Description: Published

Description: 107-121

Description: 9T. Geochimica dei fluidi applicata allo studio e al monitoraggio di aree sismiche

Description: JCR Journal

Description: The occurrence of high volumes of methane during tunneling operations is a critical safety factor that can influence the choice of different technical approaches for tunnel design and construction. Moreover, gas accumulation can be influenced by fluid migration along spatially focused preferential pathways (i.e. points along faults and fracture zones) that can result in highly variable gas concentrations along the tunnel trace. This paper proposes a methodological approach to minimize the risks, and costs, related to tunnel construction in rocks with potentially high methane concentrations. This approach combines soil gas geochemistry and structural geology surveys along and across the main faults and fracture systems that occur in the study area. The procedure is based on near-surface sampling and consists of a two-pronged approach: the measurement of fault zone gas emissions and their classification as barrier or conduit zones. Moreover, it is illustrated the importance of measuring a wide spectrum of different gas species, not just methane, for a more accurate interpretation of the geological, geochemical, and structural systems. This is due to the potential for multiple gas origins, different gas associations, and various alteration and oxidation processes (e.g., CH4 oxidation into CO2) that can modify the geochemical signal along the flow path as gas migrates towards the surface.

Description: Published

Description: 1035-1038

Description: 9T. Geochimica dei fluidi applicata allo studio e al monitoraggio di aree sismiche

Description: Although CO2 capture and storage in deep, offshore reservoirs is a proven technology, as illustrated by over 15 years of operation of the Sleipner site in the Norwegian North Sea, potential leakage from such sites into the overlying water column remains a concern for some stakeholders. Therefore, we are obliged to carefully assess our ability to predict and monitor the migration, fate, and potential ecosystem impact of any leaked CO2. The release of bubbles from the sea floor, their upward movement, and their dissolution into the surrounding water controls the initial boundary conditions, and thus an understanding of the behavior of CO2 bubbles is critical to address such issues related to monitoring and risk assessment. The present study describes results from an in situ experiment conducted in 12 m deep marine water near the extinct volcanic island of Panarea (Italy). Bubbles of a controlled size were created using natural CO2 released from the sea floor, and their evolution during ascent in the water column was monitored via both video and chemical measurements. The obtained results were modelled and a good fit was obtained, showing the potential of the model as a predictive tool. These preliminary results and an assessment of the difficulties encountered are examined and will be used to improve experimental design for the subsequent phase of this research.

Description: Published

Description: 397–403

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

Description: JCR Journal

Description: The major processes that control the genesis of potassic volcanic rocks, like the timing of multi-stage mantle metasomatism, remain largely unclear. In an attempt to clarify the timing of the metasomatic process, a detailed geochronologic and geochemical study has been conducted on the ultrapotassic rocks of the Colli Albani Volcanic District (Central Italy). New 40Ar/39Ar data coupled with literature and newly performed 87Sr/86Sr, 143Nd/144Nd and chemical data allow us to precisely delineate the time-dependent geochemical variations of the magmas erupted at the Colli Albani Volcanic District and to better define mantle source processes responsible for their genesis. The temporal geochemical variations observed in the Colli Albani magmas indicate that: i) the ultrapotassic magmas originated from a metasomatized mantle source in which phlogopite is the potassium-bearing phase; ii) the partial melting of the mantle source involved mainly phlogopite and clinopyroxene (±olivine), whereas the role of accessory phases was less significant; and iii) the metasomatic process that led to the formation of the phlogopite in the mantle can be reasonably related to events that have occurred during the Paleozoic Era

Description: Published

Description: 151-164

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

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

Description: 4V. Processi pre-eruttivi

Description: JCR Journal

Description: The analysis of trace metals and metalloids, and the Sr-isotopic systematics were applied to 16 must samples from vines growing in the Sesia Val Grande Supervolcano UNESCO Global Geopark in the northern Piedmont Region (Italy), a land worldwide famous for the production of quality Nebbiolo-based red wines. Twenty-four elements were measured in each sample with inductively coupled plasma-mass spectrometry (ICP-MS). The results indicate a wide variability in trace element concentration in musts from the different vineyards. In particular, Rb and Sr reach their maximum at 5110 and 694 µg L−1, respectively, reflecting the geological nature of the magmatic bedrocks. Fe, Cu, Pb and Ba concentrations reach 3118, 1200, 130 and 720 µg L−1, respectively, suggesting a source from iron oxide, Pb–Zn and Ba ores associated to the volcanic activity. The 87Sr/86Sr ratio is in the range 0.711608–0.718160, showing a highly radiogenic signature which is uncommon in must/wine. This is consistent with the high 87Sr/86Sr isotopic ratio of the old rhyolitic bedrocks. Furthermore, the 87Sr/86Sr ratio in musts linearly correlates with the corresponding 87Rb/86Sr ratio, reflecting the Rb and 87Sr release from primary minerals during pedogenesis and matching the initial 87Sr/86Sr ratio of the parent bedrocks magmatic reservoir, thus assuming importance for authenticity assessment.

Description: Published

Description: 1027–1035

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

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

Description: 4V. Processi pre-eruttivi

Description: JCR Journal

Description: The Neapolitan volcanic area (Southern Italy), which includes the Phlegrean Volcanic District and the Somma– Vesuvius complex, has been the site of intense Plio-Quaternary magmatic activity and has produced volcanic rocks with a subduction-related geochemical and isotopic signature. High-Mg, K-basaltic lithic lava fragments dispersed within hydromagmatic tuff of the Solchiaro eruption (Procida Island) provide constraints on the nature and role of both the mantle source prior to enrichment and the subduction-related components. The geochemical data (Nb/Yb, Nb/Y, Zr/Hf) indicate a pre-enrichment source similar to that of enriched MORB mantle. In order to constrain the characteristics of subducted slab-derived components added to this mantle sector, new geochemical and Sr–Nd-isotopic data have been acquired on meta-sediments and pillow lavas from Timpa delle Murge ophiolites. These represent fragments of Tethyan oceanic crust (basalts and sediments) obducted during the Apennine orogeny, and may be similar to sediments subducted during the closure of the Tethys Ocean. Based on trace element compositions (e.g., Th/Nd, Nb/Th, Yb/Th and Ba/Th) and Nd-isotopic ratio, we hypothesize the addition of several distinct subducted slab-derived components to the mantle wedge: partial melts from shales and limestones, and aqueous fluids from shales, but the most important contribution is provided by melts from pelitic sediments. Also, trace elements and Sr–Nd-isotopic ratios seem to rule out a significant role for altered oceanic crust. Modeling based on variations of trace elements and isotopic ratios indicates that the pre-subduction mantle source of the Phlegrean Volcanic District and Somma–Vesuvius was enriched by 2–4% of subducted slab-derived components. This enrichment event might have stabilized amphibole and/or phlogopite in the mantle source. 6% degree of partial melting of a phlogopite-bearing enriched source, occurring initially in the garnet stability field and then in the spinel stability field can generate a melt with trace elements and Sr– Nd-isotopic features matching those of high-Mg, K-basalts of Procida Island. Furthermore, 2% partial melting of the same enriched source can reproduce the trace elements and isotopic features of the most primitive magmas of Somma–Vesuvius, subsequently modified by assimilation of continental crust during fractional crystallization processes at mid-lower depth. Combined trace element and Sr–Nd isotope modeling constrains the age of the enrichment event to 45 Ma ago, suggesting that the Plio-Quaternary magmatism of the Neapolitan area is postorogenic, and related to the subduction of oceanic crust belonging to the Tethys Ocean

Description: Published

Description: 165-183

Description: 2T. Deformazione crostale attiva

Description: 3T. Sorgente sismica

Description: 4T. Sismicità dell'Italia

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

Description: JCR Journal

Description: Persistent degassing of closed-conduit explosive volcanoes may be used to inspect and monitor magmatic processes. After interaction with shallow hydrothermal fluids, volcanic gases collected at surface can differ substantially from those exsolved from magma. We report here on an innovative approach to identify and separate the contribution of variable magmatic components from fumarolic gases, by processing the 30-year-long geochemical dataset from the Campi Flegrei caldera, Southern Italy. The geochemical record shows periodic variations, which are well correlated with geophysical signals. Such variations are interpreted as due to the time-varying interplay of two magma degassing sources, each differing in size, depth, composition, and cooling/crystallization histories. Similar multiple degassing sources are common at explosive volcanoes, with frequent ascent and intrusion of small magma batches. Our innovative method permits the identification of those magma batches, which contributes to the interpretation of unrest signals, forecasting and assessment of volcanic hazards

Description: Published

Description: 95-104

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

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

Description: 4V. Processi pre-eruttivi

Description: JCR Journal

Description: The focus of this study is Anthemountas basin in northern Greece, where land subsidence phenomena had been previously identified. The basin has a NNW-SSE orientation, which is optimal to the currently acting ~ N-S extension field in the back-arc Aegean area and is bordered to its north and south edge by two, well-pronounced faults. The region of study is located close to the greater metropolitan city of Thessaloniki and comprises a number of critical facilities including the city’s international airport. The research object is the monitoring of the evolution of the displacement at Anthemountas graben, using InSAR time-series and the investigation of the dominant driving mechanism. We show new surface displacement results from the ENVISAR satellite, and overall, an enhanced dataset of SAR time-series is presented, spanning the period 1992 to 2010, by using the satellites ERS1, ERS2 and ENVISAT. Results indicate a continuously deforming environment in both decades, with an increasing magnitude. The detailed study of the deformation pattern together with the analysis of in situ data defines aquifer overpumping as the main cause of the detected displacement of both decades. Critical regions are examined in detail, as for example: an area close to Thermi, the town of Perea and the Thessaloniki’s international airport, a major hub of the Balkans. The latter was subjected to an increasing deforming velocity during the monitoring period. Overall, we conclude that a water management plan should be of high priority for the area.

Description: Published

Description: 518

Description: 2T. Deformazione crostale attiva

Description: JCR Journal

Description: Renewed seismic activity of Cotopaxi, Ecuador, began in January 2001 with the increased number of long-period (LP) events, followed by a swarm of volcano-tectonic (VT) earthquakes in November 2001. In late June 2002, the activity of very-long-period (VLP) (2 s) events accompanying LP (0.5–1 s) signals began beneath the volcano. The VLP waveform was characterized by an impulsive signature, which was accompanied by the LP signal showing non-harmonic oscillations. We observed temporal changes of both the VLP and LP signals from the beginning until September 2003: The VLP signal gradually disappeared and the LP signal characterized by decaying harmonic oscillations became dominant. Assuming possible source geometries, we applied a waveform inversion method to the observed waveforms of the largest VLP event. Our inversion and particle motion analyses point to volumetric changes of a sub-vertical crack as the VLP source, which is located at a depth of 2–3 km beneath the northeastern flank. The spectral analysis of the decaying harmonic oscillations of LP events shows frequencies between 2.0 and 3.5 Hz, with quality factors significantly above 100. The increased VT activity and deformation data suggest an intrusion of magma beneath the volcano. A release of gases with small magma particles may have repetitively occurred due to the pressurization, which was caused by sustained bubble growth at the magma ceiling. The released particle-laden gases opened a crack above the magma system and triggered the resonance of the crack. We interpret the VLP and LP events as the gas-release process and the resonance of the crack, respectively.

Description: Published

Description: 119–133

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

Description: JCR Journal

Description: Guagua Pichincha, located 14 km west of Quito, Ecuador, is a stratovolcano bisected by a horseshoe-shaped caldera. In 1999, after some months of phreatic activity, Guagua Pichincha entered into an eruptive period characterized by the extrusion of several dacitic domes, vulcanian eruptions, and pyroclastic flows. We estimated the three-dimensional (3-D) P-wave velocity structure beneath Guagua Pichincha using a tomographic inversion method based on finite-difference calculations of first-arrival times. Hypocenters of volcano-tectonic (VT) earthquakes and long-period (LP) events were relocated using the 3-D P-wave velocity model. A low-velocity anomaly exists beneath the caldera and may represent an active volcanic conduit. Petrologic analysis of eruptive products indicates a magma storage region beneath the caldera, having a vertical extent of 7–8 km with the upper boundary at about sea level. This zone coincides with the source region of deeper VT earthquakes, indicating that a primary magma body exists in this region. LP swarms occurred in a cyclic pattern synchronous with ground deformation during magma extrusions. The correlation between seismicity and ground deformation suggests that both respond to pressure changes caused by the cyclic eruptive behavior of lava domes.

Description: Published

Description: 333–351

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

Description: JCR Journal