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  • 1
    Publication Date: 2017-04-04
    Description: Seismic shots recorded during the SERAPIS experiment were used to search a 1D elastic and inelastic model of the Gulf of Pozzuoli, south of the CampiFlegrei caldera. Waveforms were gaussian filtered in the range 5-8 Hz with afrequency step of 0.5 Hz and a half-width of the filter equal to 0.5 Hz. A cleardispersion of the most energetic propagation mode was revealed. This pro-perty of the surface wave in the gulf of Pozzuoli was theoretically reprodu-ced using the classical wave-number technique. To infer the best fit propaga-tion model, we developed a semi-automated procedure of fitting of filteredtraces with progressive adjustment of the model. The quality of the fitting wasestimated using the semblance among each couple of waveform (syntheticand observed). Our formulation allowed us also to estimate the error onmodel parameter by mapping the noise on seismograms on the semblance. The obtained 1D model confirms that in average intrinsic Qp at the CampiFlegrei caldera is of the order of 300-500 which is a background value higherthan that of other volcanic areas. This report is a summary of a part of the phd thesis in Earth Sciences atUniversity of Bari of Maria Trabace.
    Description: I.N.G.V.
    Description: Published
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: open
    Keywords: Campi Flegrei ; SERAPIS project ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: report
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  • 2
    Publication Date: 2017-04-04
    Description: We here propose a method for rapid, high-frequency seismogram generation that makes use of an algorithm to automatically generate an exhau- stive set of seismic phases that produce an appreciable amplitude on the sei- smogram. The method uses a hierarchical order of rays and seismic phases generation, taking into account some existence constraints for a ray-path and some physical constraints. To compute synthetic seismograms, the COMRAD code (from the Italian: “COdice Multifase per il RAy-tracing Dinamico”) uses as its core a dynamic ray-tracing code. To validate the code, we have computed in a layered medium synthetic seismograms using both COMRAD and a code which computes the complete wavefield by the discrete wavenumber method. The seismograms are compared according to a time-frequency misfit criteria based on the continuous wavelet transform of the signals. The comparison shows that the ray-theory seismogram is enough complete and moreover, the time for the computing of the synthetics using the COMRAD code (truncating the ray series at the 10th generation) is 3-4-fold less than that needed for the Axitra code (to a frequency of 25 Hz).
    Description: I.N.G.V.
    Description: Published
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: open
    Keywords: seismic phases ; Axitra code ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: report
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  • 3
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    Doppiavoce Napoli
    Publication Date: 2012-02-03
    Description: La rete sismo/accelerometrica e le metodologie di early warning sismico descritte in questo volume costituiscono uno dei più validi risultati della strategia...
    Description: Published
    Description: 4.1. Metodologie sismologiche per l'ingegneria sismica
    Description: reserved
    Keywords: early warning sismico ; 04. Solid Earth::04.06. Seismology::04.06.04. Ground motion ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book
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  • 4
    Publication Date: 2017-04-03
    Description: Elastic parameters derived from seismic reflection data provide information on the lithological contrast at an interface and support the geological interpretation.We present a method to estimate elastic parameter contrasts at a given interface in a 1-D layered medium from PS-to-PP amplitude ratios. The method is applied to synthetic data to demonstrate its possibilities and limitations. First results for real data acquired in the Campi Flegrei caldera (southern Italy) reveal a gas-bearing layer at around 3 km depth and indicate a strong negative velocity contrast at 7.5 km depth, possibly related to the presence of partial melt.
    Description: I.N.G.V.
    Description: Published
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: open
    Keywords: Campi Flegrei caldera ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: report
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  • 5
    Publication Date: 2017-04-04
    Description: I.N.G.V.
    Description: Published
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: open
    Keywords: The Campi Flegrei caldera ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: report
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  • 6
    Publication Date: 2019-11-04
    Description: We examine here a number of parameters that define the source of the earthquake that occurred on 23rd July 1930 in Southern Italy (in the Irpinia region). Starting from the source models proposed in different studies, we have simulated the acceleration field for each hypothesized model, and compared it with the macroseismic data. We then used the hybrid stochastic-deterministic technique proposed by Zollo et al. (1997) for the simulation of the ground motion associated with the rupture of an extended fault. The accelerations simulated for several sites were associated with the intensities using the empirical relationship proposed by Trifunac and Brady (1975), before being compared with the available data from the macroseismic catalogue. A good reproduction of the macroseismic field is provided by a normal fault striking in Apenninic direction (approximately NW-SE) and dipping 55° toward the SW.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: 1930 Irpinia earthquake ; ground motion simulation ; kinematic source model ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
    Format: 2295606 bytes
    Format: application/pdf
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  • 7
    Publication Date: 2017-04-04
    Description: The accurate determination of locations and magnitudes of seismic events in a monitored region is important for many scientific, industrial and military studies and applications; for these purposes a wide variety of seismic networks are deployed throughout the world. It is crucial to know the performance of these networks not only in detecting and locating seismic events of different sizes throughout a specified source region, but also by evaluating their location errors as a function of the magnitude and source location. In this framework, we have developed a method for evaluating network performance in surface and borehole seismic monitoring. For a specified network geometry, station characteristics and a target monitoring volume, the method determines the lowest magnitude of events that the seismic network is able to detect (Mw detect), and locate (Mw loc) and estimates the expected location and origin time errors for a specified magnitude. Many of the features related to the seismic signal recorded at a single station are considered in this methodology, including characteristics of the seismic source, the instrument response, the ambient noise level, wave propagation in a layered, anelastic medium and uncertainties on waveform measures and the velocity model. We applied this method to two different network typologies: a local earthquake monitoring network, Irpinia Seismic Network (ISNet), installed along the Campania-Lucania Apennine chain in Southern Italy, and a hypothetic borehole network for monitoring microfractures induced during the hydrocarbon extraction process in an oil field. The method we present may be used to aid in enhancing existing networks and/or understanding their capabilities, such as for the ISNet case study, or to optimally design the network geometry in specific target regions, as for the borehole network example.
    Description: Published
    Description: 793-806
    Description: 4.1. Metodologie sismologiche per l'ingegneria sismica
    Description: JCR Journal
    Description: restricted
    Keywords: Earthquake ground motions ; Computational seismology ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 8
    Publication Date: 2019-11-04
    Description: The records of an aftershock (M ~ 4) of a moderate size event (M = 5.9) which occurred along the subduction zone of Guerrero (Mexico), are used as empirical Green functions (EGF) to determine the source characteristics of the mainshock and of its smaller size (M = 5.5) foreshock. The data consist of accelerograms recorded by the Guerrero Accelerograph Array, a high dynamic range strong motion array. The three events appear to be located close to each other at distances much smaller than the source to receiver distances. The fault mechanism of the mainshock is computed by non-linear inversion of P polarity readings and S wave polarizations determined at two near source stations. The foreshock and aftershock fault mechanisms are similar to that of the mainshock as inferred from long period data and shear wave polarization analysis. The maximum likelihood solution is well constrained, indicating a typical shallow dipping thrust fault mechanism, with the P-axis approximately oriented in a SSW direction. The source time functions (STFs) of the mainshock and foreshock events are determined using a new method of deconvolution of the EGF records at three strong motion sites. In this method the STF of the large event is approximated by a superposition of pseudo triangular pulses whose parameters are determined by a non-linear inversion in frequency domain. The source time function of the mainshock shows the presence of two separate pulses, which can be related to multiple rupture episodes. The relative location of mainshock sub-events is done by using plots of isochrones computed from measurementes of the time delay between pulses on the STF records at each station. The first sub-event is located no more than 2.5-3 km away from the other along the fault strike. The STF retrieved from foreshock records shows single pulse waveforms. The computed STFs are used to estimate seismic moments, source radii and stress release of the events assuming a circular fault model and constant rupture velocity. The final rupture model for the mainshock indicates the successive breaking of two nearby large slip patches having sizes of the order of a few kilometers and with the rupture propagating at an average speed close to the shear wave velocity.
    Description: JCR Journal
    Description: open
    Keywords: empirical Green function ; source time function ; pseudo-triangular pulse ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
    Format: 5927068 bytes
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  • 9
    Publication Date: 2019-11-04
    Description: In this paper we evalllate the seismic amplification effects in the town of Benevento llsing records of an explo- sion of 500 kg fired at abollt 7 km. Seismic records were obtained at 43 selected sites in the city by digital three-component stations. A data selection performed on the signal-to-noise ratio reduced the available data to 26 stations. We used the spectral ratio techniques to evaluate the amplification effects of each recording site compared both to the average spectrum calculated over 26 stations and to a reference seismic station. The shapes of the spectral ratios were classified according to the geological characteristics of the site. A characteristic shape of the spectral ratio was observed to be related to the specific structure of the subsoil. In particular, the sites on basin sediments (Lagonegro Unit) and Middle Pleistocene conglomerates failed to show amplification effects; the sites on thick alluvial deposits showed amplification in the 5-9 Hz range; finally, sites on alluvial-lacustrine deposits amplified the seismic signal at frequencies depending on the characteristics and the thickness of the deposit. In addition, damage distribution caused by the 1688 earthquake in Benevento was related to the thickness of the surface layers in the ancient built-up area of the town. The study of the spectral ra- tios showed that these deposits amplify ground motion at frequencies between 9 and 12 Hz, i.e. frequencies close to the natural period of the most widespread buildings at that time in Benevento. Geological and seismic data were jointly used to carry out a zonation of the urban area of Benevento on the basis of homogeneous seismic responses. The validity of this analysis is limited to the main frequency band and amplitude of ground motion produced by the explosions.
    Description: JCR Journal
    Description: open
    Keywords: site effects ; spectral ratio ; Southern Apennines ; Benevento ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
    Format: 5321663 bytes
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  • 10
    Publication Date: 2019-11-04
    Description: We applied a hybrid stochastic-deterministic method to simulate the strong ground motion characteristics associated with the September 26, 1997 Umbria-Marche main shocks. One hundred different rupture processes on previously inferred fault planes were simulated. The maps of computed PGA (mean values from 100 simulations) show a SE alignment for the 00:33 event and a NW alignment for the 09:40 event, in accordance with the macroseismic data. Moreover, we found a good agreement between the predicted 1ó interval for the PGA values and the data recorded at several accelerometric stations. As a further test, we computed the response spectra at the station Cerreto di Spoleto and found a satisfactory agreement with the synthetic results.
    Description: JCR Journal
    Description: open
    Keywords: kinematic source model ; strong motion simulation ; Umbria-Marche main shocks ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
    Format: 4802705 bytes
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