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  • 1
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    PANGAEA
    In:  Supplement to: Palumbo, Eliana; Flores, José-Abel; Perugia, Carmen; Petrillo, Zaccaria; Voelker, Antje H L; Amore, Filomena Ornella (2013): Millennial scale coccolithophore paleoproductivity and surface water changes between 445 and 360ka (Marine Isotope Stages 12/11) in the Northeast Atlantic. Palaeogeography, Palaeoclimatology, Palaeoecology, 383-384, 27-41, https://doi.org/10.1016/j.palaeo.2013.04.024
    Publication Date: 2023-07-03
    Description: A high resolution coccolithophore study was carried out in order to improve the understanding of the paleoceanographic evolution and changes in paleoproductivity occurring off the Iberian Margin (IM) between 445 and 360 ka, i.e. during late Marine Isotope Stage 12 to 11. Coccolithophore assemblages allowed reconstructing surface water changes characterized by millennial-scale oscillations (~1.5 kyr cycles) involving Portugal or Iberian Poleward Currents (PC and IPC) prevalence. Changes in paleoproductivity, possibly related to the upwelling of Eastern North Atlantic Central Waters (ENACW) - of sub-tropical (ENACWst) or sub-polar origin (ENACWsp) - were also recognized. This study also permitted detecting abrupt events (stadial/interstadial-type oscillations) and revealed that changes in paleoproductivity are related to opposite dynamics during glacial and interglacial stages, with the reversed setting being established during the deglaciation. Furthermore, a possible control of half and fourth precessional cycle components, on the occurrence of abrupt changes within the assemblages' structure, during the deglaciation, is proposed on the basis of wavelet analysis results applied to selected taxa.
    Keywords: Accumulation rate, Gephyrocapsa, small; Accumulation rate, nannofossils; AGE; Calculated; CALYPSO; Calypso Corer; Coccoliths; Coccolithus pelagicus ssp. azorinus; Coccolithus pelagicus ssp. pelagicus; Counting, coccoliths; Dissolution index; Florisphaera profunda; Gephyrocapsa, small; Gephyrocapsa caribbeanica; Gephyrocapsa margereli; Gephyrocapsa oceanica; Iberian slope; Marion Dufresne (1995); MD03-2699; MD134; Nannofossils, reworked fossil; Nannofossils, warm water taxa; PICABIA
    Type: Dataset
    Format: text/tab-separated-values, 3064 data points
    Location Call Number Limitation Availability
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  • 2
    facet.materialart.
    Unknown
    PANGAEA
    In:  Supplement to: Palumbo, Eliana; Flores, José-Abel; Perugia, Carmen; Emanuele, Dario; Petrillo, Zaccaria; Rodrigues, Teresa; Voelker, Antje H L; Amore, Filomena Ornella (2013): Abrupt variability of the last 24 ka BP recorded by coccolithophore assemblages off the Iberian Margin (core MD03-2699). Journal of Quaternary Science, 28(3), 320-328, https://doi.org/10.1002/jqs.2623
    Publication Date: 2023-07-20
    Description: A high-resolution coccolithophore study allowed reconstructing sea surface conditions during the last 24 ka BP off the Iberian Margin. Variations in nannoplankton accumulation rate, cold-water species, Florisphaera profunda, Umbilicosphaera sibogae and Coccolithus pelagicus ssp. azorinus trends suggest the occurrence of substantial changes in surface water dynamics. Palaeoproductivity shows changes during the glacial and the interglacial transition from intense glacial upwelling to persistent interglacial stratification. A drastic productivity decline occurred between ~18 and 13 ka BP related to the arrival of subpolar waters indicated by the presence of the subarctic subspecies C. pelagicus pelagicus and increased percentages of tetra-unsaturated alkenones. Abrupt variability at core MD03-2699 during the last 24 ka BP was observed in palaeoproductivity and sea surface temperatures proxies. Increases of reworked species fluxes were observed during the Last Glacial Maximum and during the transition to the Holocene, likely connected to turbidity currents and/or contourites formed by Mediterranean outflow intensification. In addition, C. pelagicus ssp. pelagicus presence, Gephyrocapsa muellerae and tetra-alkenone percentages reveal rapid coolings coeval with the Holocene Bond cycles and rapid climate coolings recognized for the Northern Hemisphere between 11.02 and 1.7 ka BP and associated with subpolar water arrival at the site.
    Keywords: Accumulation rate, nannofossils; Accumulation rate, nannofossils, reworked; AGE; Calculated; CALYPSO; Calypso Corer; Coccoliths; Coccolithus pelagicus ssp. pelagicus; Counting, coccoliths; Emiliania huxleyi; Florisphaera profunda; Gephyrocapsa muellerae; Iberian slope; Marion Dufresne (1995); MD03-2699; MD134; Nannofossils, cold water taxa; Nannofossils, reworked fossil; Nannofossils, warm water taxa; PICABIA; Preservation; Preservation index; Umbilicosphaera sibogae
    Type: Dataset
    Format: text/tab-separated-values, 1946 data points
    Location Call Number Limitation Availability
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  • 3
    Publication Date: 2020-11-30
    Description: The inter-arrival times of the post 2000 seismicity at Campi Flegrei caldera are statistically distributed into different populations. The low inter-arrival times population represents swarm events, while the high inter-arrival times population marks background seismicity. Here, we show that the background seismicity is increasing at the same rate of (1) the ground uplift and (2) the concentration of the fumarolic gas specie more sensitive to temperature. The seismic temporal increase is strongly correlated with the results of recent simulations, modelling injection of magmatic fluids in the Campi Flegrei hydrothermal system. These concurrent variations point to a unique process of temperature-pressure increase of the hydrothermal system controlling geophysical and geochemical signals at the caldera. Our results thus show that the occurrence of background seismicity is an excellent parameter to monitor the current unrest of the caldera.
    Description: Published
    Description: 4472
    Description: 4V. Dinamica dei processi pre-eruttivi
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 4
    Publication Date: 2021-05-12
    Description: The recent signs of reawakening at Campi Flegrei caldera (Southern Italy) received a great deal of attention due to the issues related to the volcanic risk management in a densely populated area. This paper explores relations between ground deformations, seismicity and geochemical time series in the time span 2004–2016. The aim is to unravel primary processes of unrest and the related indicators which may change in time. Data structure and interactions among variables were examined applying the clustering analysis, the correlations and the Granger causality test. The hierarchical agglomerative clustering detected two sub-periods which were further investigated. In both sub-period causal links were observed between variables while correlations did not appear and vice versa. Thus, well established formal approaches are required to study causal relations. Granger test results indicate that during 2004–2011 the awakening unrest could be mainly ascribed to hydrothermal system pressure fluctuations, probably induced by deep-rooted fluids injection, and that ground deformation together with CO2/H2O appears the most suitable geo-indicators. The 2011–2016 sub-period is characterized by enhanced dynamical connectivity. Granger test results suggest that the unrest is driven by a more localized and shallower thermohydromechanical engine. CO/CO2, He/CH4 and ground deformation velocity are mutually interacting appearing the most suitable geo-indicators.
    Description: INGV Project PRIN n. 20174 × 3P29 FLUIDS
    Description: Published
    Description: 185
    Description: 5V. Processi eruttivi e post-eruttivi
    Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio
    Description: JCR Journal
    Keywords: Granger test; ground deformation; degassing; seismicity; volcanic unrest ; 04. Solid Earth
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
    Location Call Number Limitation Availability
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  • 5
    Publication Date: 2020-11-20
    Description: This paper presents the results obtained by an audio-magnetotelluric (AMT) survey carried out crossing the western sector of Montemurro village (Southern Italy) affected by an intense hydrogeological instability. The AMT investigation was aimed to settle the question concerning the possible prosecution toward SE of the Eastern Agri Fault System whose surficial evidences could be blinded by extensive landslides phenomena and by anthropization of the territory. The AMT profile was oriented in NE-SW direction, orthogonal to the main geological structures of the investigated area. It crossed longitudinally the area affected by instability. The AMT model provides new insights on already known faults (i.e. Montemurro Faults) and imaged their in-depth immersion thus answering to still open geological question in the investigated areas. Furthermore, the high resolution of the model allowed the imaging of the boundaries, in terms of resistivity contrast, between material affected/unaffected by the sliding dynamics or characterized by an higher water content. The results provide new knowledge about the geological and geoelectrical structures in the area. They will be fully integrated with the results of the on-going research activities in the area and will represent an additional step for the multiscale and multiparametrical characterization of the Agri Valley geological setting.
    Description: Published
    Description: 1156-1171
    Description: 2TR. Ricostruzione e modellazione della struttura crostale
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 6
    Publication Date: 2020-11-30
    Description: This work presents a systematic study for testing the effectiveness of Self-Organizing Map (SOM) neural networks in filtering magnetotelluric (MT) data affected by cultural noise. Although the MT method is widely used for geophysical investigation of the Earth’s interior, it is very sensitive to anthropogenic noise sources (e.g., power lines, electric railways, etc.), which can generate transient artificial electromagnetic fields disturbing the MT records. Thus, when not properly detected, man-made noises could lead to a distortion of the MT impedance tensors and consequently to wrong estimate of the resulting subsoil resistivity distribution. The choice to use SOM networks to filter noisy MT data comes from the expectation that the impedance tensors, estimated by Discrete Wavelet Transform analysis of MT time series, will cluster differently in presence of noise. This expectation is confirmed by the results of our extensive study on synthetic MT signals affected by temporally localized noise, which show that noisy and noise-free impedance tensor values distribute in well separate clusters. Moreover, as the SOM analysis provides a grid of weights (clusters), each one close to a particular subset of the input data, a criterion is proposed for selecting the cluster that gives the most reliable impedance tensor estimate. An application of the proposed SOM-based filtering procedure to actual MT data demonstrates its efficiency in denoising real MT signals.
    Description: Published
    Description: 12-22
    Description: 2V. Struttura e sistema di alimentazione dei vulcani
    Description: JCR Journal
    Keywords: MT data denoising ; Discrete wavelet transform ; Neural networks ; Self-Organizing Maps
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
    Location Call Number Limitation Availability
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  • 7
    Publication Date: 2021-07-14
    Description: Fumaroles are a common manifestation of volcanic activity that are associated with large emissions of gases into the atmosphere. These gases originate from the magma, and they can provide indirect and unique insights into magmatic processes. Therefore, they are extensively used to monitor and forecast eruptive activity. During their ascent, the magmatic gases interact with the rock and hydrothermal fluids, which modify their geochemical compositions. These interactions can complicate our understanding of the real volcanic dynamics and remain poorly considered. Here, we present the first complete imagery of a fumarolic plumbing system using three-dimensional electrical resistivity tomography and new acoustic noise localization. We delineate a gas reservoir that feeds the fumaroles through distinct channels. Based on this geometry, a thermodynamic model reveals that near-surface mixing between gas and condensed steam explains the distinct geochemical compositions of fumaroles that originate from the same source. Such modeling of fluid interactions will allow for the simulation of dynamic processes of magmatic degassing, which is crucial to the monitoring of volcanic unrest.
    Description: Published
    Description: id 7580
    Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
    Location Call Number Limitation Availability
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  • 8
    Publication Date: 2020-03-25
    Description: Campi Flegrei (CF) is a caldera in Southern Italy, which has manifested signs of significant unrest in the last years. Indeed, during volcanic crises, the ground of Campi Flegrei caldera begin to grow steadily, the earthquake swarms become more common and strong variations in the chemical composition of fumaroles are observed. In the Campi Flegrei volcanic area there is a spread ground deformation monitoring network. In the years 1983-85 the bradiseism showed an increasing trend of ground uplift with a fairly fast velocity. In the following years (1986-2014) the phenomenon tends to decrease: the earthquakes number is near to zero, the vertical ground displacement decreases, the fumaroles modify the gas emissions, the soil temperature decreases. The main object of this study is to evaluate, by means of variables comparison, in a counterclockwise periods, the relationship among geochemical data of fumaroles, earthquakes and ground deformations, to discover which variables can be considered signals (geochemical indicator) of the bradyseismic events during an unrest period.
    Description: Published
    Description: 2473–2489
    Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio
    Description: N/A or not JCR
    Keywords: geochemical variables ; earthquakes ; ground deformation ; bradyseism ; volcanic risk ; multivariate analysis
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 9
    Publication Date: 2018-05-02
    Description: Magnetotellurics (MT) is one of the prominent geophysical methods for underground deep exploration and, thus, appropriate for applications to petroleum and geothermal research. However, it is not completely reliable when applied in areas characterized by intense urbanization, as the presence of cultural noise may significantly affect the MT impedance tensor estimates and, consequently, the apparent resistivity values that describe the electrical behaviour of the investigated buried structures. The development of denoising techniques of MT data is thus one of the main objectives to make magnetotellurics reliably even in urban or industrialized environments. In this work we propose an algorithm for filtering of MT data affected by temporally localized noise. It exploits the discrete wavelet transform (DWT) that, thanks to the possibility to operates in both time and frequency domain, allows to detect transient components of the MT signal, likely due to disturbances of anthropic nature. The implemented filter relies on the estimate of the ellipticity of the polarized MT wave. The application of the filter to synthetic and field MT data has proven its ability in detecting and removing cultural noise, thus providing apparent resistivity curves more smoothed than those obtained by using raw signals.
    Description: Published
    Description: 135-141
    Description: 2TR. Ricostruzione e modellazione della struttura crostale
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
    Location Call Number Limitation Availability
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  • 10
    Publication Date: 2020-01-23
    Description: The Campi Flegrei caldera is a large volcanic complex lying in the Campanian Plain, Southern Italy. During its history the caldera experienced episodes of bradyseism and intense swarm seismicity. The mechanism leading to unrest episodes is still debated, and great efforts are ongoing to improve the knowledge of this structure and its evolution due to the high volcanic risk in such a densely populated area. Here we present a resistivity model from a two‐dimensional inversion of audiomagnetotelluric data acquired along an approximately 5.6‐km long profile crosscutting the Solfatara‐Pisciarelli district and the Agnano plain. The resistivity model shows (1) very low resistivity values confined in the first 500 m of depth both in correspondence of the Solfatara‐Pisciarelli districts and the Agnano depression; (2) a resistive plume that extends underneath the Solfatara crater down to 2,000‐ to 3,000‐m depth, and (3) an adjoining relative conductive unit eastward. We discuss the resistivity structures in a multidisciplinary framework integrating inedited geochemical and seismological observations with existing surface geology and subsurface information. The Solfatara‐Pisciarelli district and the Agnano plain, both being expression of intense hydrothermal activity, show different characteristics. Below the Solfatara‐Pisciarelli area, the shallow conductive zone is interpreted as a faulted clay cap that overlies a highly active vapor‐dominated reservoir characterized by a convective mechanism. Conversely, below the Agnano plain, a liquid phase seems to prevail in the reservoir. The spatiotemporal variations of seismicity imply a combined action of preexisting tectonic lineaments and fluid interaction between the gas/steam reservoir and the outflow zone.
    Description: Published
    Description: 5336-5356
    Description: 2V. Struttura e sistema di alimentazione dei vulcani
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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