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  • 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy
  • Data analysis / ~ processing
  • Textbook of informatics
  • Wiley  (10)
  • Elsevier Science Limited  (7)
  • Wiley-Blackwell  (5)
  • American Institute of Physics (AIP)
  • Nature Publishing Group
  • Periodicals Archive Online (PAO)
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  • 1
    Publication Date: 2017-04-04
    Description: Using a multidisciplinary dataset based on gravimetric, seismic, geodetic and geological observations,we provide an improved picture of the shallow structure and dynamics of the southern edge of the Tyrrhenian subduction zone.With a local earthquake tomographywe clearly identify twomain crustal domains in the upper 15 kmcharacterized by different P-wave velocity values: a high-velocity domain comprising southeasternmost Tyrrhenian Sea, NE Sicily and Messina Straits, and a low-velocity domain comprising Mt. Etna and eastern Sicily. The transition between the two domains shows a good spatial correspondence with a wider set of faults including the Taormina Fault System (TFS) and the Aeolian–Tindari–Letojanni Fault System (ATLFS), two nearly SE-striking fault systems crossing northeastern Sicily and ending on the Ionian shoreline of Sicily according to many investigators. Within this set of faults, most of the deformation/seismicity occurs along the northern and central segments of ATLFS, compared to lowactivity along TFS. A lack of seismicity (both recent and historical) is observed in the southern sector of ATLFS where, however, geodetic data reveal significant deformation. Ourmultidisciplinary dataset including offshore observations suggests the southeastward continuation of the ATLFS into the Ionian Sea until joiningwith the faults cutting the Ionian accretionarywedge described in the recent literature. Our findings imply the existence of a highly segmented crustal shear zone extending from the Aeolian Islands to the Ionian Abyssal plain, that we believe plays the role of accommodating differential motion between the Southern Tyrrhenian unit and the western compressional domain of Sicily. The ATLFS, which is a main part of the inferred shear zone, behaves similarly to what often observed at the edges of retreating subduction
    Description: Published
    Description: 205-218
    Description: 1T. Geodinamica e interno della Terra
    Description: 2T. Tettonica attiva
    Description: 3T. Pericolosità sismica e contributo alla definizione del rischio
    Description: 1A. Geomagnetismo e Paleomagnetismo
    Description: 6A. Monitoraggio ambientale, sicurezza e territorio
    Description: JCR Journal
    Description: restricted
    Keywords: subduction edge ; seismic velocity structure ; 04. Solid Earth::04.01. Earth Interior::04.01.99. General or miscellaneous ; 04. Solid Earth::04.02. Exploration geophysics::04.02.99. General or miscellaneous ; 04. Solid Earth::04.02. Exploration geophysics::04.02.02. Gravity methods ; 04. Solid Earth::04.02. Exploration geophysics::04.02.04. Magnetic and electrical methods ; 04. Solid Earth::04.02. Exploration geophysics::04.02.06. Seismic methods ; 04. Solid Earth::04.03. Geodesy::04.03.99. General or miscellaneous ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations ; 04. Solid Earth::04.03. Geodesy::04.03.03. Gravity and isostasy ; 04. Solid Earth::04.03. Geodesy::04.03.04. Gravity anomalies ; 04. Solid Earth::04.03. Geodesy::04.03.05. Gravity variations ; 04. Solid Earth::04.03. Geodesy::04.03.06. Measurements and monitoring ; 04. Solid Earth::04.03. Geodesy::04.03.07. Satellite geodesy ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.06. Rheology, friction, and structure of fault zones ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.05. Geomagnetism::04.05.99. General or miscellaneous ; 04. Solid Earth::04.05. Geomagnetism::04.05.03. Global and regional models ; 04. Solid Earth::04.05. Geomagnetism::04.05.04. Magnetic anomalies ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous ; 04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution ; 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy ; 04. Solid Earth::04.07. Tectonophysics::04.07.99. General or miscellaneous ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.04. Plate boundaries, motion, and tectonics ; 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress ; 04. Solid Earth::04.07. Tectonophysics::04.07.06. Subduction related processes ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
    Publication Date: 2017-04-04
    Description: We document quantitatively observations of quasi-Love waves obtained at permanent (Italian National Seismic Network) and temporary seismic stations deployed in Italy between 2003 and 2006 (Retreat, CAT/SCAN projects). We analyzed large earthquakes with source parameters that favor quasi-Love wave generation within this time-span, including the Sumatra–Andaman earthquake of 12/26/04. The presence or the absence of the quasi-Love phase is compared to the smoothed anisotropic pattern defined by the numerous SKS splitting measurements obtained in peninsular Italy, and to the Italian upper mantle structure as defined by seismic tomography. The large-scale anisotropic features, responsible for shear-wave splitting and documented also by Pn and surface-wave anisotropy, generally display the correct geometry to explain the scattered quasi-Love waves. Quasi-Love observations do not demand a tilted-axis anisotropic geometry. We argue instead for anisotropy with laterally-variable horizontal symmetry axis in the upper mantle below the Italian peninsula.
    Description: Published
    Description: 26-38
    Description: 1T. Geodinamica e interno della Terra
    Description: JCR Journal
    Description: restricted
    Keywords: Seismic anisotropy ; Quasi-Love ; Italy ; 04. Solid Earth::04.01. Earth Interior::04.01.02. Geological and geophysical evidences of deep processes ; 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy ; 04. Solid Earth::04.07. Tectonophysics::04.07.06. Subduction related processes
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 3
    Publication Date: 2017-04-04
    Description: An automatic analysis code called ANISOMAT+ has been developed and improved to automatically retrieve the crustal anisotropic parameters fast polarization direction (ϕ) and delay time (δt) related to the shear wave splitting phenomena affecting seismic S-wave. The code is composed of a set of MatLab scripts and functions able to evaluate the anisotropic parameters from the three-component seismic recordings of local earthquakes using the cross-correlation method. Because the aim of the code is to achieve a fully automatic evaluation of anisotropic parameters, during the development of the code we focus our attention to devise several automatic checks intended to guarantee the quality and the stability of the results obtained. The basic idea behind the development of this automatic code is to build a tool able to work on a huge amount of data in a short time, obtaining stable results and minimizing the errors due to the subjectivity. These behaviors, coupled to a three component digital seismic network and a monitoring system that performs automatic pickings and locations, are required to develop a real-time monitoring of the anisotropic parameters.
    Description: Published
    Description: 62-68
    Description: 1T. Geodinamica e interno della Terra
    Description: 2T. Tettonica attiva
    Description: 4T. Fisica dei terremoti e scenari cosismici
    Description: 6T. Sismicità indotta e caratterizzazione sismica dei sistemi naturali
    Description: 3IT. Calcolo scientifico e sistemi informatici
    Description: JCR Journal
    Description: restricted
    Keywords: shear wave splitting, Earthquake forecast, Anisotropy, Cross-correlation method ; 04. Solid Earth::04.01. Earth Interior::04.01.02. Geological and geophysical evidences of deep processes ; 04. Solid Earth::04.02. Exploration geophysics::04.02.06. Seismic methods ; 04. Solid Earth::04.02. Exploration geophysics::04.02.07. Instruments and techniques ; 04. Solid Earth::04.04. Geology::04.04.01. Earthquake geology and paleoseismology ; 04. Solid Earth::04.04. Geology::04.04.11. Instruments and techniques ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics ; 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques ; 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress ; 05. General::05.01. Computational geophysics::05.01.01. Data processing ; 05. General::05.01. Computational geophysics::05.01.05. Algorithms and implementation
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 4
    Publication Date: 2017-04-04
    Description: Competing geodynamic scenarios proposed for northern Apennines (Italy) make very different predictions for the orientation of strain in the upper mantle. Constraints on the pattern are offered by observations of seismic anisotropy. Previous study of the anisotropy beneath the northern Apennines used birefringence of core-refracted shear waves (SKS phases), and demonstrated the presence of two domains: Tuscan and Adria. In the transition between the two domains, across the Apennines orogen, anisotropy measurements reflect a complex deep structure. To define better the upper-mantle structure beneath this area we analyze seismological data recorded by a set of seismic stations that operated for 3 years, between 2003 and 2006, located in the outer part of the Apennines belt, in the Adria terrane, collected by the RETREAT Project. Directionally distributed sets of SKS records were inverted for layered anisotropic structures with a well-tested method, adding new results to previous hypotheses for this area. New data analysis argues for two-layer anisotropy for sites located on the Apennines wedge and also one site in the Tuscan terrane. Beneath the wedge an upper layer with nearly north-south fast polarization pervades the lithospheric mantle, while at depth a nearly NW–SE Apennines-parallel direction is present in the lower layer. Beneath Tuscany a shallower NW–SE direction and a deeper E–W one suggest the deeper strain from active slab retreat, with a mantle-wedge circulation (i.e. an east–west corner flow), overlain by an Apennines-parallel fast polarization that could be a remnant of lower-crust deformation.
    Description: Published
    Description: 39-51
    Description: 1T. Geodinamica e interno della Terra
    Description: JCR Journal
    Description: restricted
    Keywords: Subduction zones ; Seismic anisotropy ; Northern Apennines ; 04. Solid Earth::04.01. Earth Interior::04.01.02. Geological and geophysical evidences of deep processes ; 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy ; 04. Solid Earth::04.07. Tectonophysics::04.07.06. Subduction related processes
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 5
    Publication Date: 2017-04-04
    Description: In this work, we present regional maps of the inverse intrinsic quality factor (Qi −1), the inverse scattering quality factor (Qs −1) and total inverse quality factor (Qt −1) for the volcanic environment of Deception Island (Antarctica). Our attenuation study is based on diffusion approximation, which permits us to obtain the attenuation coefficients for every single couple source-receiver separately. The data set used in this research is derived from an active seismic experiment using more than 5200 offshore shots (air guns) recorded at 32 onshore seismic stations and four ocean bottom seismometers. To arrive at a regional distribution of these values, we used a new mapping technique based on a Gaussian space probability function. This approach led us to create ‘2-D probabilistic maps’ of values of intrinsic and scattering seismic attenuation. The 2-D tomographic images confirm the existence of a high attenuation body below an inner bay of Deception Island. This structure, previously observed in 2-D and 3-D velocity tomography of the region, is associated with a massive magma reservoir. Magnetotelluric studies reach a similar interpretation of this strong anomaly. Additionally, we observed areas with lower attenuation effects that bear correlation with consolidated structures described in other studies and associated with the crystalline basement of the area. Our calculations of the transport mean-free path and absorption length for intrinsic attenuation gave respective values of ≈950 m and 5 km, which are lower than the values obtained in tectonic regions or volcanic areas such as Tenerife Island. However, as observed in other volcanic regions, our results indicate that scattering effects dominate strongly over the intrinsic attenuation.
    Description: This work has been partially supported by the Spanish project Ephestos, CGL2011–29499-C02–01, by the EU project EC-FP7 MEDiterranean SUpersite Volcanoes (MED-SUV), by the Basque Government researcher training program BFI09.277 and by the Regional project ‘Grupo de Investigaci´on en Geof´ısica y Sismolog´ıa de la Junta de Andaluc´ıa, RNM104.’ Edoardo del Pezzo was partly supported by DPC-INGV projects UNREST SPEED and V2 (Precursori).
    Description: Published
    Description: 1957-1969
    Description: 3.1. Fisica dei terremoti
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: restricted
    Keywords: Seismic attenuation; ; Seismic tomography ; Volcano seismology ; Wave scattering and diffraction ; Wave propagation ; 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 6
    Publication Date: 2017-04-04
    Description: In the present study the attenuation mechanism of seismic wave energy in and around the source area of the Chamoli earthquake of 29th March 1999 is estimated using the aftershock data. Most of the analyzed events are from the vicinity of the Main Central Thrust (MCT), which is a well-defined tectonic discontinuity in the Himalayas. Separation of intrinsic (Q 1 i ) and scattering (Q 1 s ) attenuation coefficient is done over the frequencies 1, 2, 4, 8 and 16 Hz using Multiple Lapse Time Window Analysis (MLTWA) method. It is observed that S-waves and their coda are primarily attenuated due to scattering attenuation and seismic albedo is very high at all the frequencies. A comparison of attenuation characteristics obtained using these aftershock data with those obtained using data of general seismicity of this region reveal that at lower frequencies both intrinsic and scattering attenuation for Chamoli was much higher compared to those for Garwhal-Kumaun region using general seismicity data. At higher frequencies intrinsic attenuation for Chamoli is lower than and scattering attenuation is comparable to those obtained using general seismicity data of Garwhal-Kumaun region.
    Description: A partial support has been given by Italy INGV-DPC (Istituto Nazionale di Geofisica e Vulcanologia and Dipartimento di Protezione Civile) Projects UNREST and SPEED, and by Italy’s Ministry of Education PRIN project (Seismic Hazard in Central Apennines, UR Del Pezzo).
    Description: Published
    Description: 446-454
    Description: 1T. Geodinamica e interno della Terra
    Description: 4T. Fisica dei terremoti e scenari cosismici
    Description: JCR Journal
    Description: restricted
    Keywords: MLTWA ; Intrinsic attenuation ; Scattering attenuation ; Chamoli Himalayas ; Himalayas ; 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 7
    Publication Date: 2017-04-04
    Description: The complex volcanic system of Tenerife Island is known to have a highly heterogeneous character, as recently confirmed by velocity tomography.We present new information derived from intrinsic quality factor inverse maps (Qi −1), scattering quality factor inverse maps (Qs −1) and total quality factor inverse maps (Qt −1) obtained for the same region. The data set used in this work is the result of the analysis of an active seismic experiment carried out, using offshore shots (air guns) recorded at over 85 onshore seismic stations. The estimates of the attenuation parameters are based on the assumption that the seismogram energy envelopes are determined by seismic energy diffusion processes occurring inside the island. Diffusion model parameters, proportional to Qi −1 and to Qs −1, are estimated from the inversion of the energy envelopes for any source–receiver couple. They are then weighted with a new graphical approach based on a Gaussian space probability function, which allowed us to create ‘2-D probabilistic maps’ representing the space distribution of the attenuation parameters. The 2-D images obtained reveal the existence of a zone in the centre of the island characterized by the lowest attenuation effects. This effect is interpreted as highly rigid and cooled rocks. This low-attenuation region is bordered by zones of high attenuation, associated with the recent historical volcanic activity. We calculate the transport mean free path obtaining a value of around 4 km for the frequency range 6–12 Hz. This result is two orders of magnitude smaller than values calculated for the crust of the Earth. An absorption length between 10 and 14 km is associated with the average intrinsic attenuation parameter. These values, while small in the context of tectonic regions, are greater than those obtained in volcanic regions such as Vesuvius or Merapi. Such differences may be explained by the magnitude of the region of study, over three times larger than the aforementioned study areas. This also implies deeper sampling of the crust, which is evidenced by a change in the values of seismic attenuation. One important observation is that scattering attenuation dominates over the intrinsic effects, Qi being at least twice the value of Qs.
    Description: This work has been partially supported by the Spanish project Ephestos, CGL2011-29499-C02-01, by the EU project EC-FP7 MEDiterranean SUpersite Volcanoes (MED-SUV), by the Basque Government researcher training program BFI09.277 and by the Regional project ‘Grupo de Investigaci´on en Geof´ısica y Sismolog´ıa de la Junta de Andaluc´ıa, RNM104’. EdP has been partly supported by DPC-INGV projects UNREST SPEED and V2 (Precursori).
    Description: Published
    Description: 1942-1956
    Description: 3.1. Fisica dei terremoti
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: restricted
    Keywords: Seismic attenuation ; ; Seismic tomography; ; Volcano seismology ; Wave propagation. ; 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 8
    Publication Date: 2017-04-04
    Description: According to the most common interpretation, the Apennines developed in Neogene and Quaternary times in the hanging wall of a west directed subduction zone. Seismic tomography is the most powerful tool to investigate large volume of Earth at depth, and it has been extensively applied to shed light on the geometry and shape of the subduction under the Italian peninsula. The various experiments were able to display the slab under the Southern Apennines, but even the most recent tomographic images were non-uniquely interpretable and left open questions about the characteristics of the subduction in the Northern-Central sector of the chain. We here present the results of an improved inversion experiment focused on the Northern and Central Apennines. The results do not show any pronounced subduction slab and the most evident anomaly is a low velocity body extending down to 100 km depth, located in a relatively small area under the western Tuscany. On the basis of accurate synthetic tests, we assess that, if established, a subduction like geometry should be visible in our tomographic images. We then conclude that no subduction is imaged in the Northern and Central Apennines. We thus interpret this anomaly as an asthenospheric flow. However, we cannot exclude that our result is due to intrinsic limitations of the methodology. In fact in response to the original question about the capability of local earthquake tomography to settle the matter about subduction, we underline that the absence of deep earthquakes to illuminate the model from below, the existence of seismic gaps in some sectors of the area under study even at shallow depth and the non uniqueness of interpretation of the tomographic images make local tomography unable to give alone definitive information on the deep structure of the Northern and Central Apennines.
    Description: Published
    Description: 63-73
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: restricted
    Keywords: Seismic tomography ; Apennines ; Subduction ; Asthenospheric upwelling ; 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 9
    Publication Date: 2017-04-04
    Description: To obtain accurate and reliable estimations of the major lithological properties of the rock within a studied volume, geophysics uses the joint information provided by different geophysical datasets (e.g. gravimetric, magnetic, seismic). Representation of the different types of information entering the problem using probability density functions can provide the mathematical framework to formulate their combination. The maximum likelihood estimator of the resulting joint posterior probability density functions leads to the solution of the problem. However, one key problem appears to limit the use of this solver to an extensive range of real applications: information coming from potential fields that implies the presence of dense matrices in the resolving estimator. It is well known that dense matrix systems rapidly challenge both the algorithms and the computing platforms, and are not suited to high-resolution 3D geophysical analysis. In this study, we propose a procedure that allows us to obtain fast and reliable solutions of the joint posterior probability density functions in the presence of large gravity datasets and using sophisticated model parametrization. As it is particularly CPUconsuming, this 3D problem makes use of parallel computing to improve the performance and the accuracy of the simulations. Analysis of the correctness of the results, and the performance on different parallel environments, shows the portability and the efficiency of the code. This code is applied to a real experiment, where we succeed in recovering a 3D shear-wave velocity and density distribution within the upper mantle of the European continent, satisfying both the seismological and gravity data. On a multiprocessor machine, we have been able to handle forward and inverse calculations with a dense matrix of 215.66 Gb in 18 min, 20 s and 20 min, 54 s, respectively.
    Description: NERIES INFRAST-2.1-026130, MERG-CT-2007-046522
    Description: Published
    Description: 143-156
    Description: 2.1. TTC - Laboratorio per le reti informatiche, GRID e calcolo avanzato
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: restricted
    Keywords: Parallel ; Dense matrix ; Block-cyclic distribution ; Inverse problem ; Probability density function ; ScaLAPACK ; Gravity field ; Shear-wave velocity structure ; Density structure ; 04. Solid Earth::04.01. Earth Interior::04.01.02. Geological and geophysical evidences of deep processes ; 04. Solid Earth::04.03. Geodesy::04.03.04. Gravity anomalies ; 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy ; 05. General::05.01. Computational geophysics::05.01.03. Inverse methods ; 05. General::05.01. Computational geophysics::05.01.05. Algorithms and implementation
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 10
    Publication Date: 2017-10-06
    Description: In this study we have determined detailed Vp and Vs seismic velocity models of the Ionian lithosphere subducting beneath the Tyrrhenian basin and of the surrounding mantle, by applying a post-processing technique to a large sample of local earthquake tomography studies. Our seismic velocity models permit us to infer the presence of low velocity anomalies within the slab, which we interpret as regions that are partially hydrated by fluids released during the subduction process. A petrological interpretation of the velocity anomalies gives new details on the magmatism of the volcanic Aeolian arc. Furthermore our velocity models provide a more detailed description of the boundary of the slab and its connection with the large seismically active Tindari-Letojanni strike slip system. Finally these results allow describing in detail some features of the slab as the presence of lateral and vertical tears. In conclusion, the obtained models provide some constraints for inferences on mantle circulation, and on the geodynamical evolution of the central-western Mediterranean.
    Description: Published
    Description: 751-764
    Description: 2.5. Laboratorio per lo sviluppo di sistemi di rilevamento sottomarini
    Description: JCR Journal
    Description: reserved
    Keywords: Tomography, petrology, Ionian slab ; 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 11
    Publication Date: 2020-02-24
    Description: We propose a new quantitative approach for the joint interpretation of velocity and attenuation tomography images, performed through the lateral separation of scattering and intrinsic attenuation. The horizontal P-wave scattering attenuation structure below Campi Flegrei Caldera (CFC) is imaged using the autocorrelation functions (ACF) of P-wave vertical velocity fluctuations. Cluster analysis (CA) is then applied to interpret the images derived from ACF and the available P-wave total attenuation images at 2000m quantitatively. The analysis allows the separation of intrinsic and scattering attenuation on a 2-D plane, adding new geophysical constraints to the present knowledge about this volcanic area. The final result is a new, quantitative image of the past and present tectonic and volcanological state of CFC. P-wave intrinsic dissipation dominates in an area approximately located under the volcanic centre of Solfatara, as expected in a region with a large presence of fluids and gas. A north–south scattering attenuation region is mainly located below the zone of maximum uplift in the 1982–1984 bradiseismic crisis, in the sea side of the Pozzuoli bay, but also extending below Mt Nuovo. This evidence favours the interpretation in terms of a hard but fractured body, contoured by strong S-wave scatterers, corresponding to the Caldera rim: the region is possibly a section of the residual magma body, associated with the 1538 eruption of Mt Nuovo.
    Description: Published
    Description: 1304-1310
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: reserved
    Keywords: Probability distributions ; Seismic attenuation ; Seismic tomography ; Statistical seismology ; 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 12
    Publication Date: 2017-04-04
    Description: We investigate in detail the crustal layering of the ‘Val di Chiana Basin’ (Northern Apennines, Tuscany, Italy) through receiver functions and seismic anisotropy with hexagonal symmetry. The teleseismic data set is recorded in correspondence of a typical foreland basin resulting by the progressive eastward retreat of a regional-scale subduction zone trapped between two continents. We study the azimuthal variations of the computed and binned receiver functions associated to a harmonic angular analysis to emphasize the presence of the dipping and the anisotropic structures. The resulting S-wave velocity model shows interesting and new results for this area that we discuss in a regional geodynamic contest contributing to the knowledge of the structure of the forearc of the subduction zone. A dipping interface (N192°E strike, 18° dip) has been revealed at about 1.5 km depth, that separates the basin sediments and flysch from the carbonates and evaporites. Moreover, we interpret the two upper-crust anisotropic layers (at about 6 and 17 km depth) as the Hercynian Phyllites and Micaschists, of the Metamorphic Tuscan Basement. At relatively shallow depths, the presence of these metamorphic rocks causes the seismic anisotropy in the upper crust. The presence of shallow anisotropic layers is a new and interesting feature, first revealed in the study area. Beneath the crust–mantle transition (Moho), located about 28 km depth, our analysis reveals a 7-km-thick anisotropic layer.
    Description: Published
    Description: 545-556
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: reserved
    Keywords: Seismic anisotopy ; Computational Seismology ; Wave propagation ; Subduction zone process ; Crustal structure ; Europe ; 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 13
    Publication Date: 2017-04-04
    Description: We present the surface wave dispersion results of the application of the ambient noise method to broad-band data recorded at 114 stations from the Istituto Nazionale di Geofisica e Vul- canologia (INGV) national broad-band network, some stations of the Mediterranean Very Broadband Seismographic Network (MedNet) and of the Austrian Central Institute for Me- teorology and Geodynamics (ZAMG). Vertical-component ambient noise data from 2005 October to 2007 March have been cross-correlated for station-pairs to estimate fundamental mode Rayleigh wave Green’s functions. Cross-correlations are calculated in 1-hr segments, stacked over periods varying between 3 months and 1.5 yr. Rayleigh wave group dispersion curves at periods from 8 to 44 s were determined using the multiple-filter analysis technique. The study region was divided into a 0.2◦ × 0.2◦ grid to invert for group velocity distribu- tions. Checkerboard tests were first carried out, and the lateral resolution was estimated to be about 0.6◦. The resulting group velocity maps from 8 to 36 s show the significant difference of the crustal structure and good correlations with known geological and tectonic features in the study region. The Po Plain and the Southern Alps evidence lower group veloci- ties due to soft alluvial deposits, and thick terrigenous sediments. Our results also clearly showed that the Tyrrhenian Sea is characterized with much higher velocities below 8 km than the Italian peninsula and the Adriatic Sea which indicates a thin oceanic crust beneath the Tyrrhenian Sea.
    Description: Published
    Description: 1242-1252
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: reserved
    Keywords: Tomography ; Surface waves and free oscillations ; Crustal structure ; 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 14
    Publication Date: 2017-04-04
    Description: Prominent arrivals in the coda of seismograms from the wider Alpine area can be associated with lateral reflections of Love waves at the northern Apennines mountain chain (Italy), where structural heterogeneity causes an abrupt contrast in phase velocity. We discuss an approach to image lateral heterogeneity from reflected surface waves using intermediate-period, three- component coda waveforms as sources for an adjoint wavefield that propagates the reflections backward in time. We numerically compute three-dimensional sensitivity kernels for the dependence of coda waveforms on P velocity, S velocity and density, based upon correlations between the adjoint and the regular forward wavefields. We consider synthetic coda waveforms for a simplified model of the northern Apennines, as well as real coda observations from five moderate magnitude earthquakes (M W 4.6–5.6) in the southern Alps. Wave propagation is simulated using the spectral-element method, for which a 3-D regional earth model is used in the case of real data. Single and combined event sensitivity kernels provide clear images of the reflectivity associated with the northern Apennines in kernels for density and S-wave speed. The kernels show that surface wave reflections occur near the axial zone of the mountain chain. Apart from the Apennines, the approach is able to image other smaller reflectivity patches from the coda waveforms, like the Ivrea zone in the southern Alps. Our coda misfit kernels can be integrated in a gradient-based waveform tomography, where they could enhance the shar pness of the model at lateral discontinuities.
    Description: Published
    Description: 543–554
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: reserved
    Keywords: Tomography; ; Computational seismology ; Wave scattering and diffraction ; Crustal structure ; 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 15
    Publication Date: 2017-04-04
    Description: We map the b-value in the subduction zone of theWellington region, NewZealand, using a high quality earthquake catalogue relocated with a 3-D seismic velocity model, consisting of 50 314 events that occurred between 1990 and 2005. In order to investigate heterogeneity in the crust of the overlying plate and in the upper plane of the Wadati–Benioff Zone (WBZ), we analyse a series of cross-sections perpendicular to the strike of the subduction zone. We calculate the b-values selecting events with magnitude of completeness ≥2.4 and depth ≤65 km and projecting the seismicity within 20 km on each side of the cross-sectional planes. We observe areas of high b-value (∼1.7) near the plate interface and regions of low b-value anomalies are detected both in the WBZ in the northwest region below 40 km depth and in the overlying plate in the northern South Island at 10 km depth. The anomalies are statistically significant based on Utsu’s p-test and the bootstrap method and are not data processing method or parameter dependent. We compare the b-value distribution with previously determined 3-D distributions of Vp, Vp/Vs andQp from seismic tomography. This comparison suggests that material inhomogeneity, caused by fluid filled cracks resulting from dehydration of the subducted slab and subducted sediments, is the predominant cause of b-value variation in the shallow part of this subduction zone. Our observations are consistent with a previously proposed conceptual model that fluid distribution in the shallow part of this subduction zone is controlled by the permeability of geological terranes in the overlying plate.
    Description: Published
    Description: 451-460
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: restricted
    Keywords: Seismic attenuation ; Seismic tomography ; Statistical seismology ; Subduction zone processes ; 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy ; 05. General::05.01. Computational geophysics::05.01.04. Statistical analysis
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 16
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    Wiley
    In:  Chichester, 2nd ed., xvii + 517 pp., Wiley, vol. 5, no. 22, pp. 662-664, (ISBN 0-470-87000-1 (HB), ISBN 0-470-87001-X (PB))
    Publication Date: 2005
    Keywords: GIS ; Textbook of informatics ; Textbook of geography ; geography ; management ; policy
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  • 17
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    Unknown
    Wiley
    In:  Hoboken, NJ, 633 pp., Wiley, vol. 16B, no. 2, pp. 125-169, (ISBN 0-471-26610-8)
    Publication Date: 2003
    Keywords: Textbook of mathematics ; Data analysis / ~ processing ; Modelling ; software ; manual ; computer ; algebra ; symbolic ; mathematics
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  • 18
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    Unknown
    Wiley
    In:  New York - 2nd ed., 372 pp., Wiley, vol. 1, pp. 225, (ISBN 0-471-32192-3)
    Publication Date: 1999
    Keywords: Textbook of geography ; Textbook of informatics ; GIS
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  • 19
    facet.materialart.
    Unknown
    Wiley
    In:  Chichester, 292 pp., Wiley, vol. 45, pp. ii + 37 pp. + 35 figs. + 4 tabs., (ISBN 0-471-95596-5)
    Publication Date: 1998
    Keywords: Textbook of informatics ; FTN90 ; Gegenueberstellung ; der ; beiden ; Programmiersprachen ; PIK ; Potsdam
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  • 20
    facet.materialart.
    Unknown
    Wiley
    In:  New York, Wiley, vol. 2, no. XVI:, pp. 1-14, (ISBN 0-08-043751-6)
    Publication Date: 1986
    Keywords: Data analysis / ~ processing
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  • 21
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    Unknown
    Wiley
    In:  Chichester, Wiley, vol. 231, no. 3, pp. 2-203, (ISBN 0-470-02298-1)
    Publication Date: 1982
    Keywords: Data analysis / ~ processing ; Correlation ; Seismic stratigraphy ; Seismics (controlled source seismology)
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  • 22
    facet.materialart.
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    Wiley
    In:  New York, 2nd Edition, 709 pp., Wiley, vol. 75, no. 2, pp. 2-203, (ISBN: 3-7643-7143-9)
    Publication Date: 1981
    Keywords: Correlation ; Data analysis / ~ processing ; fit ; Textbook of mathematics
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