ALBERT

Beschreibung: 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.

Beschreibung: Published

Beschreibung: 309-328

Beschreibung: 4V. Processi pre-eruttivi

Beschreibung: 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.

Beschreibung: Published

Beschreibung: 106812

Beschreibung: 2T. Deformazione crostale attiva

Beschreibung: JCR Journal

Beschreibung: 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.

Beschreibung: Published

Beschreibung: 3840 – 3847

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

Beschreibung: JCR Journal

Beschreibung: 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.

Beschreibung: Published

Beschreibung: 103402

Beschreibung: 1V. Storia eruttiva

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

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

Beschreibung: 4V. Processi pre-eruttivi

Beschreibung: 5V. Processi eruttivi e post-eruttivi

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

Beschreibung: JCR Journal

Beschreibung: 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.

Beschreibung: Published

Beschreibung: 379-411

Beschreibung: 4V. Processi pre-eruttivi

Beschreibung: 5V. Processi eruttivi e post-eruttivi

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

Beschreibung: 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.

Beschreibung: RCUK NERC DisEqm project

Beschreibung: Published

Beschreibung: 116658

Beschreibung: 5V. Processi eruttivi e post-eruttivi

Beschreibung: JCR Journal

Beschreibung: 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.

Beschreibung: Published

Beschreibung: 2742 – 2747

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

Beschreibung: JCR Journal

Beschreibung: 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.

Beschreibung: Published

Beschreibung: 3824 – 3831

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

Beschreibung: JCR Journal

Beschreibung: 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.

Beschreibung: Published

Beschreibung: 549–555

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

Beschreibung: JCR Journal

Beschreibung: 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.

Beschreibung: Published

Beschreibung: 107-121

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

Beschreibung: JCR Journal