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  • 1
    Publication Date: 2004-01-01
    Print ISSN: 0096-3941
    Electronic ISSN: 2324-9250
    Topics: Geosciences
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  • 2
    Publication Date: 2002-09-01
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
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  • 3
    Publication Date: 2020-10-16
    Description: High strain rates and intense seismic activity characterize both the boundaries and the interior of the Aegean–Anatolian plate: the availability of geodetic and geophysical data makes this region ideal to make detailed models of continental deformation. Although the deformation occurring in the Aegean–Anatolian plate may be regarded as the primary effect of the Arabian indenter push, it has already been demonstrated that this mechanism cannot account for the observed extrusion/rotation of the whole plate. We investigate the present-day steady-state anelastic deformation of the Aegean–Anatolian plate by a thin plate thermomechanical finite element (FE) model that accounts for realistic rheological mechanisms and lateral variations of lithospheric properties. Studying the region with uniform models, where average values for thermal and geometric parameters are chosen, we find that two tectonic features, in addition to the Arabian plate push, are critical to reproduce a velocity field that gives a reasonable fit to the observations. The first is the E–W constraint of NW continental Greece, related to the collision between the Aegean–Anatolian plate and the Apulia–Adriatic platform, required in the model to attain the SW orientation of the velocity field along the Hellenic Arc. The second is the trench suction force (TSF) due to subduction of the African lithosphere, which is needed to fit the observed mean extrusion velocity of 30 mm yr−1 along the Hellenic Arc. Uniform models are useful to study the sensitivity to the interplay of rheological/thermal parameters in a simplified framework but, in all cases, predict a strong deformation localized along the Hellenic Arc, whereas geodetic and seismological data show that the highest strain rates are located in western Anatolia. Furthermore, uniform models are non-unique in the sense that since we model a vertically averaged thin plate, different thermal and rheological parameters can be combined to yield the same lithospheric strength. We account for internal sources of deformation with heterogeneous models, where the available constraints on lateral variations of crustal thickness and surface heat flow have been included. The heterogeneous distribution of lithospheric strength contributes to ameliorate the fit to geodetic and stress data, since the predicted velocity field is characterized by an acceleration from E to W, with a sharp increase in the proximity of the western margin of the Anatolian peninsula, where the highest rates of intraplate deformation are observed. In our model this partitioning of the deformation is due to the different rheology of the Aegean Sea, which, being slightly deformable, transmits the TSF to the western margin of Anatolia. Our results are consistent with the interpretation of the Aegean–Anatolian system as a single, rheologically heterogeneous plate.
    Description: Published
    Description: 760-780
    Description: 2T. Deformazione crostale attiva
    Description: JCR Journal
    Keywords: Rheology ; Tectonics ; 04.07. Tectonophysics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 4
    Publication Date: 2020-10-16
    Description: We revisit the problem of inferring mantle viscosity from postglacial relative sea level (RSL) data across the Hudson Bay. We invert a recently revised data set using the Metropolis algorithm together with an annealing schedule: this method, which is well established in geophysics, is applied here for the first time to the glacial isostatic adjustment problem. The Metropolis algorithm performs a search, which is not limited to downhill moves in the model space and thus is less influenced by local minima of the misfit than traditional inverse approaches. Furthermore, its CPU requirements are far superior to Monte Carlo methods. The major drawbacks include slow convergence and the need for careful tuning of crucial variables such as the temperature schedule and the increment in the model space. When all the Hudson Bay RSL data are considered, and the viscosity of the upper mantle above the 670 km discontinuity is inverted, the best fitting solution is characterized by a viscosity close to 2 × 10^20 Pa s. However, when the shallow upper mantle and transition zone viscosity are separately inverted, other less traditional solutions with a more complex viscosity structure are found to be equally possible. A stable feature is the lower mantle viscosity, which is generally found to be close to the value of 10^21 Pa s in all of the stochastic inversions we have performed. The solutions agree with previous findings concerning both postglacial rebound observables and global geodynamics signatures.
    Description: Published
    Description: 2352
    Description: 1T. Struttura della Terra
    Description: JCR Journal
    Keywords: Postglacial Rebound ; Mantle Viscosity ; Simulated Annealing ; 04.07. Tectonophysics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 5
    Publication Date: 2020-11-02
    Description: Il raggio di Marte è solo la metà di quello della Terra, ma i suoi vulcani superano la scala dei vulcani terrestri. Il più spettacolare è il Mons Olympus che, con una altezza di 21 km ed un diametro di 600 km, è circa 100 volte più grande del Mauna Loa (Isole Hawaii). I vulcani sono situati su enormi sollevamenti tettonici come la Regione di Tharsis. Circa metà della superfice del pianeta sembra costituita da materiali vulcanici modificati da impatti di meteoriti, erosione del vento, inondazioni di acqua. Marte ha i più grandi vulcani dell’intero sistema solare. I grandi volumi di lava eruttata hanno avuto un impatto profondo sull’intero pianeta, estraendo calore e sostanze chimiche dalla profondità. Marte non può essere compreso senza studiare i suoi vulcani. Il vulcanismo, prodotto probabilmente da eruzioni esplosive colossali, ha creato strutture a scala globale come le pianure vulcaniche nell’emisfero Nord, o la misteriosa Formazione Medusa Fossae, costituita da depositi stratificati ed erosi, che si estende per quasi un terzo della zona equatoriale. La datazione di queste strutture è fatta sulla base del conteggio degli impatti di meteoriti. L’età dei depositi va da 4 miliardi a meno di 500 milioni di anni fa. Non si può escludere che la tettonica del pianeta sia ancora attiva.
    Description: Published
    Description: Pisa
    Description: 2TM. Divulgazione Scientifica
    Keywords: Mars ; Volcanoes
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Conference paper
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  • 6
    Publication Date: 2020-10-16
    Description: Recent satellite geodetic measurements help to clearly define the velocity field in the Aegean-Anatolian area. The velocity field can be broadly characterized by anticlockwise rotation of this region relative to Eurasia, around a pole located at Lat. 32.73, Long. 32.03, north of the Egyptian shoreline. Studies of the fault kinematics in the region also provide information on the time evolution of the stress field. In this work, we model deformation in the Aegean-Anatolian region to better understand the tectonic origin of the observed stress and velocity fields. We found that the observed deformation pattern can be well reproduced by imposing simple boundary conditions including: (1) northward displacement of the Arabian plate, (2) locking of eastward motion in northwestern Greece and (3) suction force at the Hellenic trench. The observed variation in the stress field occurred at 0.9 Ma can be partially explained by a change in the activity of the North Anatolian fault.
    Description: Published
    Description: 2087-2090
    Description: 2T. Deformazione crostale attiva
    Description: JCR Journal
    Keywords: Plate Motion ; Continental tectonics ; Dynamics of lithosphere and mantle ; Plate boundary ; 04.07. Tectonophysics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 7
    Publication Date: 2017-04-04
    Description: The deformation recorded at Mount Etna during the last 15 years clearly shows that there is an interplay between activity of magmatic sources and instability of the SE sector. In particular, the anomalous sliding of the SE flank can be triggered by summit or flank eruptions (e.g., 2002), but it is also observed during quiescent loading phases (e.g., 1993-1997). This deformation is usually modeled by sub-horizontal dislocation surfaces (embedded in an elastic half space) whose parameters are determined fitting the observed surface deformation. The purpose of this paper is to investigate whether models forced by a simple isotropic expansion source but taking into account the internal structure of Mount Etna are capable to focus a significant amount of horizontal deformation in the eastern flank. We perform computations based on the finite element method along a 2D cross section. The deformation models include both topography and a synthetic reconstruction of the internal layering constrained by geology, seismic tomography and experimental measurements of Etnean rocks. We study the sensitivity of the predicted surface displacement to variations of internal layers rheology and/or mechanical parameters. Our first results suggest that significant contributions to increase the deformation in the SE sector are due to plastic rheology of the clay layers and to asymmetrical distribution of elastic parameters related to the high velocity body underneath Mount Etna imaged by seismic tomography.
    Description: Published
    Description: San Francisco
    Description: 3.6. Fisica del vulcanismo
    Description: open
    Keywords: Numerical Modeling ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Abstract
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  • 8
    Publication Date: 2022-03-31
    Description: QUESTO VOLUME RACCONTA UNA STORIA DI CAMBIAMENTI. Da un lato i cambiamenti del nostro pianeta, un ambiente vivo e in continua trasformazione; dall’altro, i cambiamenti nel modo di pensare, vedere e spiegare il mondo che, nell’arco di duemila anni, hanno guidato l’uomo nella comprensione dei meccanismi che regolano l’evoluzione della Terra. Il risultato di questo lungo percorso è la teoria della Tettonica delle Placche, una delle più importanti rivoluzioni scientifiche del XX secolo. La sua enunciazione ha coronato un’epoca d’oro per le Scienze della Terra. Accolta inizialmente con scetticismo, talvolta apertamente osteggiata, è stata accettata da un’intera generazione di scienziati che hanno fatto proprie le idee sulla deriva dei continenti, ponendo le basi per il cambiamento del modo di studiare e comprendere la dinamica della Terra: dalla visione di un pianeta statico, cristallizzato nelle sue forme, si è passati alla consapevolezza di vivere su un pianeta dinamico, continuamente rimodellato dalla tettonica globale. La teoria della Tettonica delle Placche è in grado, da sola, di spiegare fenomeni apparentemente inconciliabili: l’attività sismica, l’orogenesi, la disposizione dei vulcani, il magnetismo delle rocce, la formazione di strutture come le fosse oceaniche e gli archi vulcanici, la distribuzione e la forma dei continenti, il riaggiustamento isostatico postglaciale, la distribuzione geografica delle faune e flore fossili e la sorprendente struttura dei fondali oceanici. In questo volume percorriamo un lungo viaggio attraverso le intuizioni e le scoperte degli scienziati che, più di tutti, hanno contribuito alla formulazione della teoria della Tettonica delle Placche. I geografi del XVI secolo avevano notato, per primi, la somiglianza tra i margini dei continenti che si affacciano sull’Oceano Atlantico; nei secoli successivi sono state formulate molte ipotesi per spiegare queste caratteristiche della superficie e comprendere come siano correlate con la struttura interna della Terra, fino ad arrivare all’ipotesi sulla deriva dei continenti di Alfred Wegener. All’inizio del XX secolo erano già stati raccolti tutti gli elementi per una prima formalizzazione della teoria. Ma saranno la seconda guerra mondiale, prima, e la guerra fredda, dopo, a fornire l’opportunità per studiare in modo approfondito i fondali oceanici e per realizzare le prime reti sismiche globali. I nuovi dati raccolti forniranno le evidenze più schiaccianti a sostegno della Tettonica delle Placche. Con l’avvento del nuovo millennio, l’attenzione di molti scienziati si è rivolta allo studio dei pianeti extraterrestri in cerca dei segni di attività tettonica. Oggi sappiamo infatti che ha avuto un ruolo fondamentale nella comparsa della vita sulla Terra: l’individuazione di questi segni sarà centrale per la ricerca di mondi alieni che possano aver ospitato, o potranno ospitare, la vita.
    Description: Published
    Description: 2TM. Divulgazione Scientifica
    Keywords: Tectonics ; Education ; 05.03. Educational, History of Science, Public Issues
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book
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  • 9
    Publication Date: 2022-01-03
    Description: The increase of available seismic data prompts the need for automatic processing procedures to fully exploit them. A good example is aftershock sequences recorded by temporary seismic networks, whose thorough analysis is challenging because of the high seismicity rate and station density. Here, we test the performance of two recent Deep Learning algorithms, the Generalized Phase Detection and Earthquake Transformer, for automatic seismic phases identification. We use data from the December 2019 Mugello basin (Northern Apennines, Italy) swarm, recorded on 13 permanent and nine temporary stations, applying these automatic procedures under different network configurations. As a benchmark, we use a catalog of 279 manually repicked earthquakes reported by the Italian National Seismic Network. Due to the ability of deep learning techniques to identify earthquakes under poor signal-to-noise-ratio (SNR) conditions, we obtain: (a) a factor 3 increase in the number of locations with respect to INGV bulletin and (b) a factor 4 increase when stations from the temporary network are added. Comparison between deep learning and manually picked arrival times shows a mean difference of 0.02–0.04 s and a variance in the range 0.02–0.07 s. The improvement in magnitude completeness is ∼0.5 units. The deep learning algorithms were originally trained using data sets from different regions of the world: our results indicate that these can be successfully applied in our case, without any significant modification. Deep learning algorithms are efficient and accurate tools for data reprocessing in order to better understand the space-time evolution of earthquake sequences.
    Description: Published
    Description: e2021JB023405
    Description: 4T. Sismicità dell'Italia
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 10
    Publication Date: 2021-12-14
    Description: The Italian earthquake waveform data are collected here in a dataset suited for machine learning analysis (ML) applications. The dataset consists of nearly 1.2 million three-component (3C) waveform traces from about 50 000 earthquakes and more than 130 000 noise 3C waveform traces, for a total of about 43 000 h of data and an average of 21 3C traces provided per event. The earthquake list is based on the Italian Seismic Bulletin (http://terremoti.ingv.it/bsi, last access: 15 February 2020​​​​​​​) of the Istituto Nazionale di Geofisica e Vulcanologia between January 2005 and January 2020, and it includes events in the magnitude range between 0.0 and 6.5. The waveform data have been recorded primarily by the Italian National Seismic Network (network code IV) and include both weak- (HH, EH channels) and strong-motion (HN channels) recordings. All the waveform traces have a length of 120 s, are sampled at 100 Hz, and are provided both in counts and ground motion physical units after deconvolution of the instrument transfer functions. The waveform dataset is accompanied by metadata consisting of more than 100 parameters providing comprehensive information on the earthquake source, the recording stations, the trace features, and other derived quantities. This rich set of metadata allows the users to target the data selection for their own purposes. Much of these metadata can be used as labels in ML analysis or for other studies. The dataset, assembled in HDF5 format, is available at http://doi.org/10.13127/instance (Michelini et al., 2021).
    Description: Published
    Description: 5509–5544
    Description: 4T. Sismicità dell'Italia
    Description: JCR Journal
    Keywords: 04.06. Seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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