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  • 2020-2023  (11,254)
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  • 11
    Publication Date: 2022-12-27
    Description: Magmas often experience severe disequilibrium conditions during their migration through the Earth's crust and the subsequent emplacement on its surface. During their transport, magmas are subjected to a wide range of cooling (q) and deformation rates (), generating physico-chemical perturbations in the magmatic system able to inhibit or promote crystallization processes. Quantifying the magnitude and timescale of kinetic effects is essential to correctly constrain the rheological evolution of magmas and their ability to flow. Here we present a suite of cooling deformation experiments (CDE) conducted on a basalt from Mt. Etna (Sicily, Italy) to disentangle and model the concurrent effects of q (from 1 to 10 °C/min) and (from 1 to 10 s−1) on the rheology of the system. The analysis of the temporal evolution of viscosity indicates that both q and strongly affect the onset of crystallization and achievement of a rheological cut-off over time, which represents the steep viscosity increase responsible for inhibiting magma flow. Both these rheological thresholds occur at lower T and earlier in time with increasing q, as well as at higher T and earlier in time with increasing . To reproduce the observed effects of crystallization on the apparent viscosity, we adopt a stretched exponential function that identifies two main crystallization regimes: i) a first shear-induced crystallization regime, characterized by a gentle viscosity increase and ii) a second cooling-dominated regime, marked by a steeper viscosity increase. The relative extent of these crystallization regimes strictly depends on the interplay between q and on the crystallization kinetics and suggest a first order control of q and a subordinate role of .
    Description: Published
    Description: 117725
    Description: 3V. Proprietà chimico-fisiche dei magmi e dei prodotti vulcanici
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 12
    Publication Date: 2022-12-27
    Description: La frange littorale Rades – Hammam lif est une zone côtière fortement urbanisée et industrialisée exposée depuis longtemps à la contamination par les polluants provenant essentiellement de l’oued Meliane qui constitue la voie principale de la pénétration des ETMs. Le mercure est un élément connu par sa toxicité, il se trouve naturellement sur la terre et aussi dans l’environnement à cause des activités anthropiques intenses. Le Golfe de Tunis est influencé par les apports des principaux cours d'eaux exoréiques, provenant de diverses sources de rejets d'origine domestique, industrielle et agricole. La partie sud-ouest du Golfe de Tunis, en particulier la frange littorale Rades - Hammam lif, subit depuis des années les apports des rejets provenant de l’oued Meliane. La concentration de mercure au niveau de l’oued Meliane s’échelonne de 0,02 à 0,61 (µg.g-1) et de 0,01 à 0,97 (µg.g-1) respectivement pendant la saison estivale et hivernale. Le facteur d’enrichissement indique un enrichissement modéré à extrêmement élevé d’où la pollution provient d’une origine anthropique. Le facteur de contamination montre une contamination considérable à très forte au niveau de l’oued Meliane et les stations du littoral. La répartition spatio-temporelle de Hg varie en fonction des sources de rejets installées sur la zone côtière et sur la bordure de l’oued Meliane ainsi que la direction de la dérive littorale au niveau de la côte.
    Description: The Rades - Hammam lif coast is a highly urbanized and industrialized area exposed for a long time to the contamination by pollutants coming essentially from the Meliane River which constitutes the main source of trace metals.Mercury is an element known for his toxicity, it is found naturally on earth and also in the environment due to intense human activities. The Gulf of Tunis is influenced by the contributions of the main exoreic rivers, coming from various sources of domestic, industrial and agricultural discharges. The southwestern part of the Gulf of Tunis, in particular the Rades - Hammam lif coastal fringe, has for years been subjected to the influx of discharges from the oued Meliane. The mercury concentration at the level of the oued Meliane ranges from 0.02 to 0.61 (µg.g-1) and from 0.01 to 0.97 (µg.g-1) respectively during the summer season and winter. The enrichment factor indicates moderate to extremely high enrichment where the pollution is of anthropogenic origin. The contamination factor shows considerable to very strong contamination at the level of the Meliane oued and the coastal stations. The spatio-temporal distribution of Hg varies according to the sources of releases installed on the coastal zone and on the edge of the oued Meliane as well as the direction of the littoral drift at the level of the coast..
    Description: Published
    Description: Refereed
    Keywords: Mercure ; Sédiments de surface ; pollution ; contamination
    Repository Name: AquaDocs
    Type: Journal Contribution , Refereed
    Format: 139-147
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  • 13
    Publication Date: 2022-12-27
    Description: We investigated the temporal variation of the spectral decay parameter κ before and after two main earthquakes that occurred in the central Italy region, namely the Amatrice (Mw 6.0) of 24 August 2016 and the Norcia (Mw 6.5) of 30 October 2016 earthquakes. For this analysis, we used seismograms from the central Italy dense seismic array stations, and earthquakes located at hypocenter distances r 〈 80 km, having magnitudes Mw 3.4–6.5. The dataset consists of 393 events recorded at 92 stations. We estimated, for both earthquake sequences, average functions κ˜(r) that describe the distance dependence of κ along the S-wave source-station paths using acceleration spectra from foreshocks, mainshock, and aftershocks. We observed that there was a regional attenuation drop within approximately two months after the Amatrice earthquake. Then, κ˜(r) tends to return toward the attenuation values observed before the occurrence of the main event, namely to the values of κ˜(r) obtained from the foreshocks, when the earthquake cycle is probably completed. We also estimated the near-source kappa (κs) using aftershocks from 24 August 2016 to 3 September 2016. The results show that the values of κs are lower than those from aftershocks located to the north near the epicenter of the Amatrice earthquake, suggesting that the tectonic stress was probably high near the rupture zone, and that there may be a likely fluid flow of crustal fluids. κ˜(r) obtained from the foreshocks of the Norcia earthquake is like that calculated with the records of the Amatrice aftershocks. Then, κ˜(r) drops to lower attenuation values during the Norcia main event and tends to increase again during the aftershocks. From the analysis of these two earthquake sequences that occurred in a short-time interval in central Italy, we conclude that the temporal variation of κ˜(r) could be a valuable indicator to monitor the earthquake cycle.
    Description: Published
    Description: 3037–3045
    Description: 5T. Sismologia, geofisica e geologia per l'ingegneria sismica
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 14
    Publication Date: 2022-12-27
    Description: Biennial Report 2020 for the Vesuvius - Campi Flegrei Supersite released for CEOS (Committee on Earth Observation Satellites)
    Description: Istituto Nazionale di Geofisica e Vulcanologia (INGV), Sezione OV, Napoli, Italia
    Description: Published
    Description: 2V. Struttura e sistema di alimentazione dei vulcani
    Keywords: InSAR, Satellite data, Monitoring networks ; 04.08. Volcanology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: report
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  • 15
    Publication Date: 2022-12-27
    Description: Volcanic activity typically switches between high-activity states with many eruptions and low-activity states with few or no eruptions. We present a simple two-regime physics-informed statistical model that allows interpreting temporal modulations in eruptive activity. The model enhances comprehension and comparison of different volcanic systems and enables homogeneous integration into multivolcano hazard assessments that account for potential changes in volcanic regimes. The model satisfactorily fits the eruptive history of the three active volcanoes in the Neapolitan area, Italy (Mt. Vesuvius, Campi Flegrei, and Ischia) which encompass a wide range of volcanic behaviors. We find that these volcanoes have appreciably different processes for triggering and ending high-activity periods connected to different dominant volcanic processes controlling their eruptive activity, with different characteristic times and activity rates (expressed as number of eruptions per time interval). Presently, all three volcanoes are judged to be in a low-activity state, with decreasing probability of eruptions for Mt. Vesuvius, Ischia, and Campi Flegrei, respectively.
    Description: Published
    Description: eabq4415
    Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 16
    Publication Date: 2022-12-27
    Description: The interaction of magma and wall-rocks is inevitable when magma is moving through Earth's crust. These interactions happen on different timescales and especially the short-term interactions (seconds to days) during the final ascent of the magma can induce changes in eruption dynamics. However, information on this matter is scarce and scattered in different scientific fields. We conducted this review in order to present a full picture of the state of the art for short-timescale magma–wall-rock interactions. According to the three existing studies on short-term magma–carbonate interactions, magma viscosity is the most important controlling factor for carbonate assimilation. Lower viscosity magmas enhance CO2-bubble migration away from the reaction site, resulting in a higher carbonate assimilation rate. The released CO2 plays an important role regarding eruption dynamics since a higher CO2 release rate would result in accelerated magma ascent and may increase eruption intensity. Despite the importance for hazard assessment, important factors (pressure, magma composition, vapour phase solubilities, carbonate clast properties) for carbonate assimilation in general and CO2 release rate in particular are not or only poorly constrained. This review presents the present-day knowledge of short-term magma–carbonate interaction that is relevant to establish the basis for future work concerning magma–wall-rock interactions.
    Description: Published
    Description: 4V. Processi pre-eruttivi
    Keywords: 04.08. Volcanology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 17
    Publication Date: 2022-12-27
    Description: Biennial Report 2022 for the Vesuvius - Campi Flegrei Supersite released for CEOS (Committee on Earth Observation Satellites)
    Description: Istituto Nazionale di Geofisica e Vulcanologia (INGV), Sezione OV, Napoli, Italia
    Description: Published
    Description: 2V. Struttura e sistema di alimentazione dei vulcani
    Keywords: InSAR, Satellite data, Monitoring networks ; 04.08. Volcanology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: report
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  • 18
    Publication Date: 2022-12-27
    Description: In this work, we present a comprehensive rheological database including most of the existing data relevant for crystal-bearing magmas collected from the scientific literature, covering the entire range of natural volcanic conditions, in terms of crystal content (1-80%), crystal shape (aspect ratio R from 1 to 13), and strain rate (between 10-7 and 102 s-1). Datasets were collected and discerned as a function of the information which we considered necessary for building a general systematic model describing relative viscosity of crystal-bearing magmas, such as the apparent and melt viscosity, the crystal concentration, crystal shape, and the strain rate. The selected dataset was then used for modelling the relative viscosity of a liquid-solid mixture having different concentrations of particles with different R, subjected to different strain rates. The proposed model allows us to quantitatively describe the rheological behaviour of crystal-bearing magmatic systems.
    Description: Published
    Description: 247
    Description: 3V. Proprietà chimico-fisiche dei magmi e dei prodotti vulcanici
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 19
    Publication Date: 2022-12-27
    Description: This work provides the mean ground deformation rates and ground displacement time series of the Campi Flegrei caldera (Italy) retrieved by satellite remote sensing data analysis from 1992 to 2021. Synthetic Aperture Radar (SAR) images acquired by ERS 1-2 (1992-2002), Envisat (2003-2011) and Cosmo-SkyMed (2011-2021) are processed by multi-temporal SAR Interferometry (InSAR) approach using the same technique, parameters and reference system, to obtain for the first time a homogeneous and time-continuous dataset. The validation of the InSAR products is carried out by comparison with the measurements provided by precise levelling lines and cGNSS stations. The produced outcomes offer an overview on the temporal behaviour of ground deformation at Campi Flegrei along an unprecedented time window of about 30 years and can be exploited by the scientific community for supporting and improving the knowledge of the dynamics of the caldera.
    Description: Published
    Description: 728
    Description: 2V. Struttura e sistema di alimentazione dei vulcani
    Description: JCR Journal
    Keywords: InSAR, cGNSS, Levelling ; 04.03. Geodesy
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 20
    Publication Date: 2022-12-27
    Description: The characterization of the fling-step represents a challenging task due to the shortage of near-source records with permanent tectonic displacement and the limitation in retrieving the fling-amplitude from accelerometric waveforms. In recent years, innovative ground-motion processing techniques have been developed for a more accurate estimation of both fling-displacements and spectral displacements in contrast to traditional bandpass filtering, although their application is still unusual. In this paper, we exploit the newly released dataset of the Near-Source Strong-motion records (NESS2) uniformly processed with the extended BASeline COrrection technique (eBASCO), against which we propose: (1) a new empirically-based ground motion model (GMM) for the prediction of the fling-step, and (2) an adjustment factor of the spectral displacements predicted by a reference GMM to account for the contribution of the fling-step at long periods. Such models are in agreement with observations and existing GMMs, and thus could be advantageously employed in seismic hazard analyses.
    Description: Published
    Description: 107294
    Description: 5T. Sismologia, geofisica e geologia per l'ingegneria sismica
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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