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  • 04. Solid Earth::04.02. Exploration geophysics::04.02.06. Seismic methods  (6)
  • 04. Solid Earth::04.02. Exploration geophysics::04.02.05. Downhole, radioactivity, remote sensing, and other methods  (2)
  • high frequency  (2)
Collection
Years
  • 1
    Publication Date: 2020-11-11
    Description: We show the preliminary seismic monitoring of a historical church in L’Aquila (central Italy), which was strongly damaged by the 2009 seismic sequence. This structure, S. Maria del Suffragio church, suffered the collapse of a great part of the dome during the April 6th 2009 Mw 6.1 earthquake. In this paper, recordings of ambient noise and local earthquakes have been analyzed. The seismic data were recorded by means of a dynamic monitoring system (19 mono-directional and 3 tri-directional piezoelectric accelerometers) and of two velocimeters, with all the instruments installed into the church. The aim of this re- search is the evaluation of the performance of the accelerometers of the monitoring system in case of low-amplitude vibrations. Simple techniques of analysis commonly employed in the seismic characterization of buildings have been applied. The reliability of the in-situ data was evaluated and the main modal parameters (natural frequencies and damping ratio) of the church were presented
    Description: Published
    Description: S0654
    Description: 1IT. Reti di monitoraggio e Osservazioni
    Description: JCR Journal
    Description: restricted
    Keywords: waves and wave analysis, instruments and techniques ; 04. Solid Earth::04.02. Exploration geophysics::04.02.06. Seismic methods
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
    Publication Date: 2017-04-04
    Description: In order to retrieve a 2D background velocity model and to retrieve the geometry and depth of shallow crustal reflectors in the Southern Apennines thrust belt a separate inversion of first arrival traveltimes and reflected waveforms was performed. Data were collected during an active seismic experiment in 1999 by Enterprise Oil Italiana and Eni-Agip using a global offset acquisition geometry. A total of 284 on-land shots were recorded by 201 receivers deployed on an 18 km line oriented SW–NE in the Val D’Agri region (Southern Apennines, Italy). The two-step procedure allows for the retrieval of a reliable velocity model by using a non-linear tomographic inversion and reflected waveform semblance data inversion. The tomographic model shows that the P wave velocity field varies vertically from approximately 3 km/s to 6 km/s within 4 km from the Earth’s surface. Moreover, at a distance of approximately 11 km along the profile, there is an abrupt increase in the velocity field. In this zone indeed, an ascent from 2 km depth to 0 km above sea level of the 5.2 km/s iso-velocity contour can be noted. The retrieved velocity can be associated with Plio-Pleistocene clastic deposits outcropping in the basin zone and with Mesozoic limestone deposits. The inversion of waveform semblance data shows that a P-to-P reflector is retrieved at a depth of approximately 2 km. This interface is deeper in the north-eastern part of the profile, where it reaches 3 km depth and can be associated with a limestone horizon.
    Description: Published
    Description: 541-553
    Description: 3.8. Geofisica per l'ambiente
    Description: JCR Journal
    Description: reserved
    Keywords: Southern Apennines ; non-linear inversion ; 04. Solid Earth::04.02. Exploration geophysics::04.02.06. Seismic methods
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 3
    Publication Date: 2017-04-04
    Description: We present here two methods to obtain reflection images of upper crust seismic reflectors. The techniques are based on migration and waveform coherence analysis of reflected seismic phases recorded in local earthquake seismograms and in active seismic data. The first method is a move-out and stack of reflected seismic phases in local earthquake recordings. The theoretical travel times of reflected/converted phases in a 1D medium for a given interface depth and velocity model are used to align the recordings in time. The locations and origin times of events are initially estimated from the P and S arrival times. Different seismic gathers are obtained for each reflected/converted phase at the interface under consideration, and the best interface depth is chosen as that which maximizes the value of a semblance function computed on moved-out records. This method has been applied to seismic records of microearthquakes that have occurred at the Mt. Vesuvius volcano, and it confirms the reports of an 8- to 10-km-deep seismic discontinuity beneath the volcano that was previously identified as the roof of an extended magmatic sill. The second is a non-linear 2D method for the inversion of reflection travel times aimed at the imaging of a target upper-crust reflector. This method is specifically designed for geophysical investigations in complex geological environments (oil investigations, retrieving of images of volcano structures) where the presence of complex structures makes the standard velocity analysis difficult and degrades the quality of migrated images. Our reflector is represented by nodes of a cubic-spline that are equally spaced at fixed horizontal locations. The method is based on a multiscale approach and uses a global optimization technique (genetic algorithm) that explores the whole of the parameter space, i.e. the interface position nodes. The forward problem (the modelling of reflection travel times) is solved using the finite-difference solver of Podvine & Lecomte (1991) and using an a priori known background velocity model. This non-linear method allows the automated determination of the global minimum (or maximum) without relying on estimates of the gradient of the objective function in the starting model and without making assumptions about the nature of the objective function itself. We have used two types of objective functions. The first is a least-squares L2 norm, defined as the sum of the squared differences between the observed and the calculated travel times. The second is based on coherence measures (semblance). The main advantage of using coherence measures is that they do not require travel-time picking to assess the degree of fit to the data model. Thus, the time performance of the whole procedure is improved and the subjectivity of the human operators in the picking procedure is removed. The methods are tested on synthetic models and have been applied to a subset of data that was collected during the active seismic experiments performed in September 2001 in the gulfs of Naples and Pozzuoli in the framework of what is known as the SERAPIS project.
    Description: Published
    Description: 157-178
    Description: open
    Keywords: NONE ; 04. Solid Earth::04.02. Exploration geophysics::04.02.06. Seismic methods ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis ; 05. General::05.01. Computational geophysics::05.01.01. Data processing
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
    Format: 1339356 bytes
    Format: application/pdf
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  • 4
    Publication Date: 2017-04-04
    Description: We propose a two-dimensional, non-linear method for the inversion of reflected/ converted traveltimes and waveform semblance designed to obtain the location and morphology of seismic reflectors in a lateral heterogeneous medium and in any source-to-receiver acquisition lay-out. This method uses a scheme of non-linear optimization for the determination of the interface parameters where the calculation of the traveltimes is carried out using a finite-difference solver of the Eikonal equation, assuming an a priori known background velocity model. For the search for the optimal interface model, we used a multiscale approach and the genetic algorithm global optimization technique. During the initial stages of inversion, we used the arrival times of the reflection phase to retrieve the interface model that is defined by a small number of parameters. In the successive steps, the inversion is based on the optimization of the semblance value determined along the calculated traveltime curves. Errors in the final model parameters and the criteria for the choice of the best-fit model are also estimated from the shape of the semblance function in the model parameter space. The method is tested and validated on a synthetic dataset that simulates the acquisition of reflection data in a complex volcanic structure. This study shows that the proposed inversion approach is a valid tool for geophysical investigations in complex geological environments, in order to obtain the morphology and positions of embedded discontinuities.
    Description: Published
    Description: 527–540
    Description: 3.8. Geofisica per l'ambiente
    Description: JCR Journal
    Description: reserved
    Keywords: non-linear method ; reflected/ converted traveltimes ; 04. Solid Earth::04.02. Exploration geophysics::04.02.06. Seismic methods
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 5
    Publication Date: 2017-04-04
    Description: The normal fault-system responsible of the 2009 Mw 6.1 L'Aquila earthquake (Paganica-San Demetrio fault-system) comprises several narrow, fault-parallel valleys of controversial origin. We investigated a key section of the southeastern portion of this fault network along the small Verupola Valley. In order to characterize its nature and possible tectonic activity, we applied multiple-geosciences techniques able to image at depth the structure associated to this peculiar landform. We integrated magnetometry, 2-D P wave and resistivity tomography, surface waves and seismic noise analysis coupled with field mapping, shallow boreholes and trenching. According to our results, the Verupola Valley is a ∼30–40-m-deep graben controlled by a SW-dipping master fault and synthetic splays paired with an antithetic NE-dipping fault. The SW-dipping splays are active and cut very shallow (〈2 m deep) Late Pleistocene sediments. The small amount of cumulated vertical offset (∼15 m) across the conjugated system may indicate a young fault inception or very low Quaternary slip-rates. Due to its structural continuity with the adjacent mapped strands of the Paganica–San Demetrio fault network, we relate the Verupola Valley to the recent activity of the southeastern segment of this fault system. We also suggest that other fault-parallel valleys can have the same tectonic origin and setting of the Verupola Valley. This latter represents a scale-independent analogue from metric scale (exposed in the palaeoseismological trenches) to the Middle Aterno Basin scale (seen from seismic profiles and fault mapping). Overall, the imaged structural style is coherent with the regional tectonic setting due to Quaternary crustal extension.
    Description: FIRB Abruzzo: High-resolution analyses for assessing the seismic hazard and risk of the areas affected by the 2009 April 6 earthquake’, No RBAP10ZC8K_005
    Description: Published
    Description: 1676-1691
    Description: 2T. Tettonica attiva
    Description: JCR Journal
    Description: open
    Keywords: Magnetic and electrical properties; Seismicity and tectonics; Site effects; Seismic tomography; Continental neotectonics; Fractures and faults ; 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::04.04. Geology::04.04.09. Structural geology ; 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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  • 6
    Publication Date: 2019-11-04
    Description: In this paper we studied the physical properties of the Gulf of Naples (Southern Italy) for its use as a communication channel for the acoustic transmission of digital data acquired by seismic instruments on the seafloor to a moored buoy. The acoustic link will be assured by high frequency acoustic modems operating with a central frequency of 100 kHz and a band pass of 10 kHz. Since the maximum depth of the sea is about 300 m and the planned horizontal distance between the seismic instruments and the buoy is 2 km, the acoustic data transmission shall be near horizontal. In this study the signal-to-noise ratio is plotted against depth and distance from the source, thus defining the limit after which the transmitted information becomes unreliable. Using ray-theory, we compute the amplitudes of a transmitted signal at a grid of 21×12 receivers to calculate the transmission loss at each receiver. The signal-to-noise ratio is finally computed for each receiver knowing also the transmitter source level and the acoustic noise level in the Gulf of Naples. The results show that the multipath effects predominate over the effects produced by the sound velocity gradient in the sea in the summer period. In the case of omnidirectional transmitters with a Source Level (SL) of 165 dB and a bit rate of 2.4 kbit/s, the results also show that distances of 1400-1600 m can be reached throughout the year for transmitter-receiver connections below 50 m depth in the underwater acoustic channel.
    Description: Published
    Description: 313-328
    Description: JCR Journal
    Description: open
    Keywords: underwater acoustics ; signal-to-noise ratio ; shallow water ; high frequency ; Gulf of Naples ; 03. Hydrosphere::03.02. Hydrology::03.02.04. Measurements and monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 7
    Publication Date: 2017-04-04
    Description: We present preliminary results from a multidisciplinary geophysical approach ap- plied to the imaging of the three-dimensional architecture of the Middle Aterno basin, close to the epicentral area of the 2009 L’Aquila earthquake (central Italy). We collected several time domain electromagnetic soundings (TDEM) coupled with seismic noise measurements focu- sing on the characterization of the bedrock/in ll interface. Our preliminary results agree with existing geophysical data collected in the area, and show that the southeastern portion of the basin is characterized by a deepening of the Mesozoic-Tertiary bedrock down to a depth of more than 450 m. We found that a joint use of electromagnetic and seismic methods signi - cantly contributes in obtaining new insights on the 3D geometry of the Middle Aterno basin. Moreover, we believe that our combined approach based on TDEM and noise measurements can be adopted to investigate similar geological settings elsewhere.
    Description: Published
    Description: Pescina (AQ), Italy
    Description: 2T. Tettonica attiva
    Description: 3T. Pericolosità sismica e contributo alla definizione del rischio
    Description: 7A. Geofisica di esplorazione
    Description: open
    Keywords: Central Apennines ; extensional basin ; TDEM ; ambient noise ; 04. Solid Earth::04.02. Exploration geophysics::04.02.99. General or miscellaneous ; 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::04.02. Exploration geophysics::04.02.07. Instruments and techniques ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.01. Earthquake geology and paleoseismology ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 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::04.06.04. Ground motion ; 04. Solid Earth::04.07. Tectonophysics::04.07.99. General or miscellaneous ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Poster session
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  • 8
    Publication Date: 2019-11-04
    Description: In this paper we studied the physical properties of the Gulf of Naples (Southern Italy) for its use as a commu- nication channel for the acoustic transmission of digital data acquired by seismic instruments on the seafloor to a moored buoy. The acoustic link will be assured by high frequency acoustic modems operating with a central frequency of 100 kHz and a band pass of 10 kHz. The main operational requirements of data transmission con- cern the near horizontal acoustic link, the maximum depth of the sea being about 300 m and the planned hori- zontal distance between seismic instruments and buoy 2 km. This study constructs the signal-to-noise ratio maps to understand the limits beyond which the clarity of the transmission is no longer considered reliable. Using ray- theory, we compute the amplitudes of a transmitted signal at a grid of 21×12 receivers to calculate the transmis- sion loss at each receiver. The signal-to-noise ratio is finally computed for each receiver knowing also the trans- mitter source level and the acoustic noise level in the Gulf of Naples. The results show that the multipath effects predominate over the effects produced by the sound velocity gradient in the sea in the summer period. In the case of omnidirectional transmitters with a Source Level (SL) of 165 dB and a baud rate of 2.4 kbit/s, the results al- so show that distances of 1400-1600 m can be reached throughout the year for transmitter-receiver connections below 50 m depth in the underwater acoustic channel.
    Description: Published
    Description: 411-426
    Description: 1.8. Osservazioni di geofisica ambientale
    Description: JCR Journal
    Description: open
    Keywords: underwater acoustics ; signal-to-noise ratio ; shallow water ; high frequency ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 9
    Publication Date: 2023-01-25
    Description: The measurements performed in Japan have shown that muon radiography is an “imaging technique” capable of providing information of the internal structure of volcanoes with a resolution and richness of details beyond the reach of conventional, non-imaging techniques. The measurements have been performed using electronic detectors or nuclear emulsions. The latter have shown excellent muon tracking capabilities and space resolution, but are lacking of the capability of electronic detectors to provide data in real time. In this paper, we examine the possibility of developing an electronic detector giving a resolution comparable to that of nuclear emulsions and with a larger area than used so far, in order to see deeper structures inside volcanoes in spite of the strong muon absorption in the rock. We specifically discuss the very challenging application of muon radiography to Mt. Vesuvius, driven by the strong social interest coming from the enormous potential danger which it represents. Applications to other volcanoes can be envisaged.
    Description: Published
    Description: 131-137
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: Volcanology ; muons ; cosmic rays ; radiography. ; 04. Solid Earth::04.02. Exploration geophysics::04.02.05. Downhole, radioactivity, remote sensing, and other methods ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 05. General::05.04. Instrumentation and techniques of general interest::05.04.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 10
    Publication Date: 2023-01-25
    Description: The MU-RAY project has the challenging aim of performing muon radiography of the summit cone of Mt. Vesuvius. The muon telescopes developed for this purpose will be available for the radiography of other volcanoes, in particular Stromboli. The scientific goals, the strategy for their implementation and the baseline detector design are discussed in detail. A tentative time schedule for the project is drawn.
    Description: Published
    Description: 145–151
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: Muon ; radiography ; volcanoes ; 04. Solid Earth::04.02. Exploration geophysics::04.02.05. Downhole, radioactivity, remote sensing, and other methods ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 05. General::05.04. Instrumentation and techniques of general interest::05.04.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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