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  • 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring  (27)
  • 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology  (16)
  • Inversion
  • Seismological Society of America  (20)
  • Istituto Nazionale di Geofisica e Vulcanologia  (16)
  • Wiley  (7)
  • 3
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Keywords
  • 1
    facet.materialart.
    Unknown
    Seismological Society of America
    Publication Date: 2018-03-12
    Description: The paper has not any abstract
    Description: Published
    Description: 720-727
    Description: 2T. Sorgente Sismica
    Description: 1IT. Reti di monitoraggio
    Description: JCR Journal
    Keywords: Earthquake ; Monitoring ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
    Publication Date: 2021-03-04
    Description: Macroseismic investigation with data collected through web- based questionnaires is today routinely applied by most impor- tant seismological institutions, such as the U.S. Geological Survey (http://earthquake.usgs.gov/earthquakes/dyfi/; last accessed December 2014), British Geological Survey (http://www. earthquakes.bgs.ac.uk/questionnaire/EqQuestIntro.html; last accessed December 2014), European-Mediterranean Seismological Centre (http://www.emsc-csem.org/Earthquake/Contribute/ choose_earthquake.php?lang=en; last accessed December 2014), Schweizerische Erdbebendienst (http://www.seismo.ethz. ch/eq/detected/eq_form/index_EN; last accessed December 2014), Bureau Central Sismologique Français (http://www .seisme.prd.fr/english.php; last accessed December 2014), and the New Zealand GeoNet project (http://www.geonet.org.nz/ quakes/; last accessed December 2014). The wide diffusion of Internet and the citizen collaboration (crowdsourcing) allow documentation of information on seismic effects and production of a macroseismic field with low costs and almost in real time. Transformation from qualitative information (as given by ques- tionnaires) to numerical quantification is a crucial issue. In the traditional evaluation of intensity, experts used to work through a complex comparison of effects basically driven by personal expe- rience. The major problem with this approach concerns the dif- ficulty in verifing and reproducing the evaluation process due to the lack of a detailed explanation of the employed workflow and to the large variability of possible cases. On the other hand, an automatic method for the estimation of macroseismic intensities needs to be completely well defined and specified in order to be reproducible and verifiable. For these reasons, this paper presents a comprehensive explanation of our intensity assessment method. A useful automatic method for intensity assessment should be computationally fast and strictly follow the macroseismic scales. To meet these requirements in 2010, we proposed a method that firstly quantified the effects using additive scores associated with each answer of the questionnaire item and then determined an intensity estimate for each questionnaire (Sbarra et al., 2010). After a trial period and having collected more than 500,000 questionnaires, we were able to thoroughly test the method. As a result of this testing, we describe here a new improved method that takes into account further factors, such as the situation and the location of the observer (Sbarra et al., 2012, 2014), to obtain a more accurate estimate of the macroseismic intensity degree at the municipality level. In this paper, we show some applications of our method with reference to the Mercalli–Cancani–Sieberg (MCS) scale, because this scale has long been used with Italian earthquakes and allows easy comparison between these intensities and other traditional ones.
    Description: Published
    Description: 985-990
    Description: 3T. Pericolosità sismica e contributo alla definizione del rischio
    Description: 5T. Sorveglianza sismica e operatività post-terremoto
    Description: 4IT. Banche dati
    Description: JCR Journal
    Description: reserved
    Keywords: Macroseismics ; intensity ; questionnaires ; attenuation ; 04. Solid Earth::04.06. Seismology::04.06.04. Ground motion ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring ; 05. General::05.01. Computational geophysics::05.01.05. Algorithms and implementation
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 3
    Publication Date: 2021-03-04
    Description: We investigate the influence of building height on the ability of people to feel earthquakes and observe that, in an urban area, short and tall buildings reach different levels of excitation. We quantify this behavior by analyzing macroseismic reports collected from individuals through the Internet, focusing on transitory effects, therefore in the elastic regime during recent earthquakes in Italy in the local magnitude (ML) range of 3 to 5.9. We find a maximum difference of 0.6 intensity units between the top floors of tall (7–10 stories) and short (1–2 stories) buildings at the highest considered magnitudes. As expected, tall buildings experience greater shaking than short buildings during large earthquakes at large source distances. However, we observe the opposite behavior at close distances when the ML is less than 3.5. These results can be explained by considering the different spectra radiated by small and large earthquakes and the different fundamental mode resonances of buildings (i.e., shorter buildings have higher resonance frequencies and vice versa). Using idealized building models excited by real acceleration time histories, we compute synthetic accelerograms on the top floors of short and tall buildings, and confirm the trend of the observed differences in felt intensities.
    Description: Published
    Description: 1803-1809
    Description: 3T. Pericolosità sismica e contributo alla definizione del rischio
    Description: JCR Journal
    Description: reserved
    Keywords: Macroseismics ; intensity ; building height ; 04. Solid Earth::04.06. Seismology::04.06.04. Ground motion ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 4
    facet.materialart.
    Unknown
    Seismological Society of America
    Publication Date: 2017-04-04
    Description: Mt. Vesuvius is a worldwide known active volcano located in Southern Italy, east of the city of Napoli. Its last eruption occurred in 1944, ending a continuous open-conduit activity that lasted for more than three centuries. After then the volcano entered into a quiescent phase. Nonetheless, the explosive style of its past activity and its proximity to densely populated areas make Mt. Vesuvius one of the most dangerous volcanoes in the world. For this reason, a comprehensive monitoring program was established, with the goal of early detection of any possible signals of unrest.
    Description: Published
    Description: 809-816
    Description: 5V. Sorveglianza vulcanica ed emergenze
    Description: JCR Journal
    Description: restricted
    Keywords: seismic array ; volcanic seismicity ; array methods ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 5
    Publication Date: 2017-04-04
    Description: Mt. Vesuvius (southern Italy) is one of the most hazardous volcanoes in the world. Its activity is currently characterized by moderate seismicity, with hypocenters located beneath the crater zone with depth rarely exceeding 5 km and magnitudes generally less than 3. The current configu- ration of the seismic monitoring network of Mt. Vesuvius consists of 18 seismic stations and 7 infrasound microphones. During the period 2006- 2010 a seismic array with 48 channels was also operative. The station distribution provides appropriate coverage of the area around the volcanic edifice. The current development of the network and its geometry, under conditions of low seismic noise, allows locating seismic events with M〈1. Remote instruments continuously transmit data to the main acquisition center in Naples. Data transmission is realized using different technological solutions based on UHF, Wi-Fi radio links, and TCP/IP client-server applications. Data are collected in the monitoring center of the Osservatorio Vesuviano (Italian National Institute of Geophysics and Volcanology, Naples section), which is equipped with systems for displaying and analyzing signals, using both real-time automatic and manual procedures. 24-hour surveillance allows to immediately communicate any significant anomaly to the Civil Protection authorities.
    Description: Published
    Description: S0450
    Description: 5V. Sorveglianza vulcanica ed emergenze
    Description: 1IT. Reti di monitoraggio e Osservazioni
    Description: JCR Journal
    Description: open
    Keywords: Vesuvius ; seismic network ; volcano monitoring ; network performance ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 6
    Publication Date: 2017-04-04
    Description: We have analyzed the recent seismicity of Mt. Vesuvius, with particular emphasis on the period 1999-2012. Since 1972 continuous observations with electromagnetic seismometers allowed the compilation of a detailed earthquake catalogue for the station OVO. Furthermore since 1999 another, more complete, catalogue for the station BKE, closer to the crater, is available. The Gutenberg-Richter distribution of magnitudes shows a temporal decrease of the b-value since 1985, with current values close to 1.0. The temporal pattern of the strain release shows a non-stationary behavior with periods of increased release rates (as in 1989-1990, 1995-1996 and 1999-2000). The spatial distribution of the seismicity consists in two main seismogenic volumes, one with hypocenters clustered below the Mt. Vesuvius crater at depths mostly between 1-6 km, and another with hypocenters clustered within the Gran Cono volcanic edifice, with depths above the sea level. We compare the statistical properties of the seismicity occurring within these two volumes and their spatial and temporal patterns. Moreover we analyze the statistical distribution of focal mechanisms for each volume. Our results point to gravity-induced stresses as the source of the shallow seismicity and of a combined effect of crustal heterogeneities, regional stress and hydrothermal dynamics for the deeper seismicity. Finally we discuss possible future developments of the seismic monitoring system in the light of the past and current seismicity.
    Description: Published
    Description: S0442
    Description: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Description: JCR Journal
    Description: open
    Keywords: Mt. Vesuvius ; seismological monitoring ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 7
    Publication Date: 2017-04-04
    Description: The computing techniques currently available for the seismic monitoring allow advanced analysis. However, the correct event classification remains a critical aspect for the reliability of real time automatic analysis. Among the existing methods, neural networks may be considered efficient tools for detection and discrimination, and may be integrated into intelligent systems for the automatic classification of seismic events. In this work we apply an unsupervised technique for analysis and classification of seismic signals recorded in the Mt. Vesuvius area in order to improve the automatic event detection. The examined dataset contains about 1500 records divided into four typologies of events: earthquakes, landslides, artificial explosions, and “other” (any other signals not included in the previous classes). First, the Linear Predictive Coding (LPC) and a waveform parametrization have been applied to achieve a significant and compact data encoding. Then, the clustering is obtained using a Self-Organizing Map (SOM) neural network which does not require an a-priori classification of the seismic signals, groups those with similar structures, providing a simple framework for understanding the relationships between them. The resulting SOM map is separated into different areas, each one containing the events of a defined type. This means that the SOM discriminates well the four classes of seismic signals. Moreover, the system will classify a new input pattern depending on its position on the SOM map. The proposed approach can be an efficient instrument for the real time automatic analysis of seismic data, especially in the case of possible volcanic unrest.
    Description: Published
    Description: S0446
    Description: 5V. Sorveglianza vulcanica ed emergenze
    Description: JCR Journal
    Description: open
    Keywords: Mt. Vesuvius ; Neural analysis ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 8
    Publication Date: 2017-04-04
    Description: The typical earthquakes occurring at Mt. Vesuvius are Volcano-Tectonic. On July 20, 2003, an unusual earthquake with low and narrow frequency content was detected. The seismograms presented an emergent onset and a nearly monochromatic spectrum at all stations of the Osservatorio Vesuviano(Istituto Nazionale di Geofisica e Vulcanologia) seismic network. The event was located at about 4 km b.s.l. close to the crater axis and an equivalent duration magnitude of 0.6 was estimated. The nature of this event was investigated by comparing its features with those of two typical Volcano-Tectonic earthquakes occurred inside the same source volume. We compared the spectral content calculating the spectrograms and the coda patterns using the Hilbert Transform. A Seismic Moment Tensor inversion was performed on the low frequency earthquake. The focal mechanisms for the two Volcano-Tectonic earthquakes were estimated with a classical technique and resulted compatible with the stress field acting on the volcano. Taking into account the clear differences with the typical Volcano-Tectonic events as well as the peculiarities retrieved from our analyses (monochromatic, low frequency spectral content, and sustained coda) and also some geochemical observations, we classify the unusual low frequency seismic event detected at Mt. Vesuvius as Long Period earthquake and propose that its origin could be linked to a pressure drop in the deep hydrothermal system.
    Description: Published
    Description: S0440
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: open
    Keywords: Volcano monitoring ; Volcanic event classification ; Long Period earthquake ; Signal analysis ; Hydrothermal system ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 9
    Publication Date: 2017-04-04
    Description: In 2012 two seismic surveys were carried out in the area of Bagnolifutura (Campi Flegrei, Naples), with the aim of characterizing the properties of the seismic noise during the drilling activity performed in the framework of the Campi Flegrei Deep Drilling Project (CFDDP; https://sites.google.com/site/cfddpproject/). During the first survey, which was conducted from 2 to 4 April, before the drilling, seven broadband three-component seismometers were installed in two different array configurations. The second survey started on November 26, in concomitance with the drilling operations and fluid injection, and ended on December 5, four days after the end of the drilling, when the maximum depth of 502 m was reached. During this period seven broadband and one short-period three-component sensors were installed. A preliminary spectral analysis was performed on samples of seismic noise; moreover the root mean square of the amplitude of the signals and the polarization parameters were calculated. The preliminary results show similar spectral and polarization features for the data of the two surveys, whereas the amplitude of the seismic noise collected during the second survey is greatly influenced by the bad meteorological conditions. As future development experimental site transfer functions from Nakamura’s technique and surface wave dispersion from array techniques will be calculated to obtain the shallow crustal structure. The results corresponding to the different phases of the drilling activity will be compared, with the aim of establishing if significant variations of the medium properties have occurred during the experiment. Moreover the recorded signals will be deeply investigated in order to detect the eventual occurrence of microseismicity induced by fluid injection and to define its features.
    Description: Published
    Description: 1-18
    Description: N/A or not JCR
    Description: open
    Keywords: Campi Flegrei ; seismic noise ; array techniques ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 10
    Publication Date: 2017-04-04
    Description: In the present paper, we will describe the field survey (Fig. 1) and the data analysis of an experiment carried out to put constraints on the magnitude detection threshold in the area of Campi Flegrei. Results show that seismic radiation emitted from VT seismic events at frequency lower than 2 Hz has a high detection threshold (minimum magnitude around 1.5). In the range between 2 and 20 Hz, VT events with magnitudes smaller than about 0.5 have a high probability to be undetected. This result indicates that noise reduction through borehole stations and/or small arrays is essential for an accurate seismic monitoring in the Campi Flegrei area.
    Description: Published
    Description: 190-198
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: restricted
    Keywords: seismic noise ; magnitude detection ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring ; 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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  • 11
    Publication Date: 2017-04-04
    Description: One of the main issues in seismic monitoring of active volcanic areas is the accurate location of earthquake hypocenters. Volcano-tectonic seismicity is often characterized by small magnitude swarms, recorded by few seismic stations with a high picking uncertainty. Sometimes events lacks clear S-wave arrivals, due to the nature of some volcanic sources. All these features, together with the complex crustal structure of volcanoes, makes the earthquake location problem critical in such areas. One of the most important effort for improving the quality of hypocenter location is the use of realistic 3D velocity models. In the last 10 years, several scientific papers proposed 2D and 3D velocity models for Mt. Vesuvius, Campi Flegrei and the Gulf of Naples. They comes from both active seismic data (VESUVIO 94, TOMOVES 96, MAREVES 97 and SERAPIS 2001 experiments) and from local earthquake tomography. In this report we propose a global unified velocity model spanning from Ischia island to Appennine Mts. that allows us to locate earthquakes in the Neapolitan volcanic areas and in the Gulf of Naples. This model comes from a weighted averaging of 5 tomographic velocity models and a background regional model. Most of the model provides only P-wave velocities, only 2 models, obtained through local earthquake tomography at Mt. Vesuvius and Campi Flegrei also gives a S-wave velocity estimate. We show the difference between this new model and the previous 1D models adopted for routine locations at INGV-Osservatorio Vesuviano. We also relocate some events, using non-linear techniques showing differences in hypocenter position from previous locations and the improvement in final traveltime residuals and location uncertainties.
    Description: Published
    Description: 375-390
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: open
    Keywords: Volcano-tectonic seismicity ; 3D velocity model ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 12
    Publication Date: 2017-04-04
    Description: In the 1980's, from an analysis of satellite images, Russian scientists reported on a short-term thermal infrared radiation enhancement that occurred before some medium-to-large earthquakes in central Asia [Gorny et al. 1988]. Since then, many researchers have been studying earthquake thermal anomalies with satellite remote sensing data [Qiang et al. 1991, Tronin 1996, Tramutoli et al. 2001, Ouzounov and Freund 2004, Saraf and Choudhury 2004, Aliano et al. 2008, Blackett et al. 2011]. Recently, abnormal surface latent heat flux [Dey and Singh 2003, Cervone et al. 2005, Qin et al. 2009, Qin et al. 2011, Qin et al. 2012], outgoing long-wave radiation [Ouzounov et al. 2007] and microwave radiation [Takashi and Tadashi 2010] have also been shown to precede earthquakes. To investigate the possible physical mechanisms of such satellite thermal anomalies, some studies conducted a series of detecting experiments on rock loaded to fracturing [Wu et al. 2000, Freund 2002, Wu et al. 2002, Wu et al. 2006a, Wu et al. 2006b, Freund et al. 2007], and some hypotheses have been proposed. These have included: leaking of pore-gas, and hence the resulting greenhouse effect [Qiang et al. 1995]; activating and recombining of p-holes during rock deformation [Freund 2002]; release of latent heat due to near-surface air ionization [Pulinets et al. 2006], and stress-induced thermal effects due to friction and fluids [Wu and Liu 2009]. According to the Istituto Nazionale di Geofisica e Vulcanologia (INGV; National Institute of Geophysics and Volcanology), two major earthquakes with almost the same large magnitudes struck northern Italy, on the Po Plain in the Emilia Region. The first hit on May 20, 2012, at 02:03 UTC, with ML 5.9 (44.89 °N, 11.23 °E; 6 km in depth), and the second on May 29, 2012, at 07:00 UTC, with ML 5.8 (44.85 °N, 11.09 °E; 10 km in depth). These caused a total of 27 deaths and widespread damage. In this study, the long-term temperature data from both satellite and ground (with greater emphasis on the satellite data) have been used to determine whether there were thermal anomalies associated with this Emilia 2012 seismic sequence. In particular, the next section will be dedicated to describing both the data and the method of analysis. In Section 3, we provide the more significant results, which we discuss in Section 4, together with the main conclusions. We acknowledge that this work cannot be exhaustive, as it will require more data and analyses. However, although further studies will be welcome, we are confident that we have done the best with the data at our disposal.
    Description: Published
    Description: 823-828
    Description: 1.10. TTC - Telerilevamento
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: open
    Keywords: earthquake event ; numerical method ; surface temperature ; Emilia-Romagna, Italy ; Emilia ; 04. Solid Earth::04.02. Exploration geophysics::04.02.05. Downhole, radioactivity, remote sensing, and other methods ; 04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 13
    Publication Date: 2021-03-01
    Description: On September 6, 2002, at 01:21 GMT, the western part of the Tyrrhenian coast of Sicily was hit by an earthquake of magnitude ML = 5.6, representing the mainshock of a seismic sequence of roughly 500 earthquakes recorded in about one month. The event, although characterized by a moderate magnitude and located some forty kilometres offshore, produced relevant macroseismic effects in the Palermo area. A macroseismic survey was carried out soon after the earthquake with the aim of defining, for Civil Protection purposes, the damage scenario over a territory which is densely urbanised. In all, 134 localities were investigated. Damage generally depended on the high vulnerability of the buildings both for problems related to the old age - as is the case of the Palermo historical centre - and for peculiar unfavourable conditions due to site effects, particularly in some quarters of the city and in the nearby locality of Ficarazzi. Damage to masonry consisted of falling plaster, failure of corner walls, diagonal cracks in walls and widening of previous fissures. Some degraded buildings, almost abandoned and with evident lack of maintenance, suffered partial structural failure of roofs and floors. As regards reinforced concrete (RC) frame buildings, several edifices with 5-10 storeys suffered cracks in partitions and infill walls, sometimes with failure of these elements, and falling plaster. Fine cracks in beams of frames have also been observed, but without determining significant structural problems. In general, damage affects the lowest storeys of the RC frame buildings. According to the European Macroseismic Scale 1998, the maximum value of intensity, 6, was assigned to Palermo and Ficarazzi. The earthquake has also provoked effects on natural surroundings. Two types of phenomena have been detected: (i) hydrological effects and (ii) slope instability processes. The most relevant was the landslide which occurred near the village of Cerda, 60 km from the epicentre.
    Description: Published
    Description: 1-15
    Description: 1.11. TTC - Osservazioni e monitoraggio macrosismico del territorio nazionale
    Description: N/A or not JCR
    Description: open
    Keywords: Palermo ; terremoto 2002 ; macrosismica ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 14
    Publication Date: 2021-03-01
    Description: Il presente lavoro è costituito dalla raccolta sistematica delle indagini macrosismiche eseguite in occasione dei terremoti di maggior rilievo verificatisi in Sicilia orientale e Calabria meridionale dal Gennaio 1999 al Gennaio 2001. I rilievi precedenti al Settembre 1999 sono stati effettuati nell’ambito delle attività del Gruppo Nazionale per la Difesa dai Terremoti, svolte presso l’Istituto Internazionale di Vulcanologia – CNR di Catania. Successivamente a tale data le indagini macrosismiche hanno costituito parte integrante delle attività di monitoraggio del Sistema Poseidon. Entrambi gli enti adesso costituiscono la sezione di Catania dell’Istituto Nazionale di Geofisica e Vulcanologia.
    Description: Published
    Description: 1-59
    Description: 1.11. TTC - Osservazioni e monitoraggio macrosismico del territorio nazionale
    Description: N/A or not JCR
    Description: open
    Keywords: Sicilia ; terremoti ; macrosismica ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 15
    Publication Date: 2017-04-04
    Description: We present the first application of a time reverse location method in a volcanic setting, for a family of long-period (LP) events recorded on Mt Etna. Results are compared with locations determined using a full moment tensor grid search inversion and cross-correlation method. From 2008 June 18 to July 3, 50 broad-band seismic stations were deployed on Mt Etna, Italy, in close proximity to the summit. Two families of LP events were detected with dominant spectral peaks around 0.9 Hz. The large number of stations close to the summit allowed us to locate all events in both families using a time reversal location method. The method involves taking the seismic signal, reversing it in time, and using it as a seismic source in a numerical seismic wave simulator where the reversed signals propagate through the numerical model, interfere constructively and destructively, and focus on the original source location. The source location is the computational cell with the largest displacement magnitude at the time of maximum energy current density inside the grid. Before we located the two LP families we first applied the method to two synthetic data sets and found a good fit between the time reverse location and true synthetic location for a known velocity model. The time reverse location results of the two families show a shallow seismic region close to the summit in agreement with the locations using a moment tensor full waveform inversion method and a cross-correlation location method.
    Description: Published
    Description: 452-462
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Volcano seismology ; Computational seismology ; Wave propagation ; 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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  • 16
    Publication Date: 2017-04-04
    Description: After the 1976 Friuli earthquake (Ms = 6.5) in north-eastern Italy that caused about 1,000 casualties and widespread destruction in the Friuli area, the Italian government established the Centro di Ricerche Sismologiche (CRS). This is now a department of the Istituto Nazionale di Oceanografia e di Geofisica Sperimentale (OGS), and it is specifically devoted to the monitoring of the seismicity of north-eastern Italy. Since its inception, the North-East Italy Seismic Network has grown enormously. Currently, it consists of 14 broad-band and 20 short-period seismic stations, all of which are telemetered to and acquired in real time at the OGS-CRS data center in Udine. Data exchange agreements in place with other Italian, Slovenian, Austrian and Swiss seismological institutes lead to a total number of 94 seismic stations acquired in real time, which confirms that the OGS is the reference institute for seismic monitoring of north-eastern Italy. Since 2002, CRS has been using the Antelope software suite as the main tool for collecting, analyzing, archiving and exchanging seismic data. SeisComP is also used as a real-time data exchange server tool. A customized web accessible server is used to manually relocate earthquakes, and automatic procedures have been set-up for moment-tensor determination, shaking-map computation, web publishing of earthquake parametric data, waveform drumplots, state-of-health parameters, and quality checks of the station by spectra analysis. Scripts for email/SMS/fax alerting to public institutions have also been customized. Recently, a real-time seismology website was designed and set-up (http://rts.crs.inogs.it/).
    Description: Istituto Nazionale di Geofisica e Vulcanologia
    Description: Published
    Description: 67-75
    Description: 1.1. TTC - Monitoraggio sismico del territorio nazionale
    Description: JCR Journal
    Description: open
    Keywords: Seismological Research Center ; OGS ; acquiring seismic data ; archiving seismic data ; analyzing seismic data ; exchanging seismic data ; real time ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 17
    Publication Date: 2017-04-04
    Description: In this paper we investigate nature and properties of narrow-band, transient seismic signals observed by a temporary array deployed in the Val Tiberina area (central Apennines, Italy). These signals are characterized by spindle-shaped, harmonic waveforms with no clear S-wave arrivals. The first portion of the seismograms exhibits a main frequency peak centred at 4.5 Hz, while the spectrum of the slowly decaying coda is peaked at about 2 Hz. Events discrimination is performed using a matched-filtering technique, resulting in a set of 2466 detections spanning the 2010 January–March time interval. From a plane-wave-fitting procedure, we estimate the kinematic properties of signals pertaining to a cluster of similar events. The repetition of measurements over a large number of precisely aligned seismograms allows for obtaining a robust statistics of horizontal slownesses and propagation azimuths associated with the early portion of the waveforms. The P-wave arrival exhibits horizontal slownesses around 0.1 s km−1, thus suggesting waves impinging at the array almost vertically. Separately, we use traveltimes measured at a sparse network to derive independent constraints on epicentral location. Ray parameters and azimuths are calibrated using slowness measurements from a local, well-located earthquake. After this correction, the joint solution from traveltime inversion and array analysis indicates a source region spanning the 1–3 km depth interval. Considerations related to the source depth and energy, and the occurrence rate which is not related to the daily and weekly working cycles, play against a surface, artificial source. Instead, the close resemblance of these signals to those commonly observed in volcanic environments suggest a source mechanism related to the resonance of a fluid–filled fracture, likely associated with instabilities in the flux of pressurized CO2.
    Description: Published
    Description: 918-928
    Description: 1.1. TTC - Monitoraggio sismico del territorio nazionale
    Description: JCR Journal
    Description: reserved
    Keywords: Fracture and flow ; Earthquake source observations ; Interface waves ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 18
    Publication Date: 2017-04-04
    Description: Paper introducing and describing the EGU2010 SM1.3 session, "Seismic Centers Data Acquisition" (http://meetingorganizer.copernicus.org/EGU2010/session/2427)
    Description: Session «SM1.3 – Seismic Centers Data Acquisition» at the General Assembly 2010 of the European Geosciences Union (EGU), taking place in Vienna (Austria) between 2–7 May 2010, was organized to present both differences and similarities in operations by different types of seismic data centers in order to share experiences and stimulate constructive discussions. Only a few, widely used, "all-in-one" data acquisition and processing packages are available for seismic data centers, two public domain tools (SeisComP and EarthWorm) and one commercial tool (Antelope). The choice for any particular tool may depend on many different criteria, from operational aspects to scientific results, or on the availability of specific requirements in relation to a specific mission. The development of EarthWorm originally started in 1993 in the USA to replace aging and vendor tied regional processing systems. Antelope, on the other hand, started around 1996 with the aim to have real-time data flow from the field sensors to the scientist. SeisComP also started in the nineties as real-time data acquisition and processing system and evolved initially towards an early warning system for seismic observatories. Protocols have been established to exchange real-time waveform data between the different packages.
    Description: Istituto Nazionale di Geofisica e Vulcanologia
    Description: Published
    Description: 1-7
    Description: 1.1. TTC - Monitoraggio sismico del territorio nazionale
    Description: JCR Journal
    Description: open
    Keywords: EGU2010 ; Seismic Centers ; Data Acquisition ; Antelope ; SeisComP ; EarthWorm ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 19
    Publication Date: 2017-04-04
    Description: A seguito dei tre eventi sismici di magnitudo ≥ 4.0, che tra il 10 e il 12 gennaio 2010 hanno colpito la zona del Fermano-Maceratese (Italia centrale), sono state installate due stazioni della rete sismica temporanea dell’INGV ad integrazione delle reti permanenti, nazionale e regionale, già presenti nell’area.
Questa zona ha una sismicità particolare confinata in uno strato sismogenetico fragile ad una profondità compresa tra 15 e 25 km meritevole di un’analisi dettagliata. Le stazioni sono state collegate in tempo reale al centro di acquisizione della Rete Sismica Nazionale dell’INGV utilizzando dei router UMTS. Questa soluzione si è rivelata estremamente rapida e conveniente. Solo una delle stazioni ha infatti risentito della debolezza del segnale UMTS, ma in generale i dati raccolti hanno contribuito a migliorare le localizzazioni ipocentrali prodotte in tempo reale presso la sala di sorveglianza sismica di Roma. L’integrazione dei dati acquisiti dalle stazioni temporanee ai dati prodotti dalle reti permanenti, ha fornito un dataset di buona qualità già rielaborato per degli studi di dettaglio dell’area.
    Description: Published
    Description: 1-30
    Description: 1.1. TTC - Monitoraggio sismico del territorio nazionale
    Description: N/A or not JCR
    Description: open
    Keywords: Emergency ; Seismic Monitoring ; 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
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 20
    Publication Date: 2017-04-04
    Description: A properly organized seismic network is a valuable tool for monitoring seismic zones and assessing seismic hazards. In this paper we propose a new method (seismic network evaluation through simulation, SNES) to evaluate the performance of hypocenter location of a seismic network. The SNES method gives, as a function of magnitude, hypocentral depth, and confidence level, the spatial distribution of the number of active stations in the location procedure and their relative azimuthal gaps, along with confidence intervals in hypocentral parameters. The application of the SNES method also permits evaluation of the magnitude of completeness (MC), the background noise levels at the stations, and assessment of the appropriateness of the velocity model used in location routine. Italy sits on a tectonically active plate boundary at the convergence of the Eurasian and African lithospheric plates and has a high level of seismicity. In this paper, we apply the SNES method to the Italian National Seismic Network (Rete Sismica Nazionale Centralizzata dell’Istituto Nazionale di Geofisica e Vulcanologia, RSNC– INGV) which has monitored Italian seismicity since the early 1980s, following the destructive 1980 Irpinia earthquake. In recent years, the RSNC–INGV has grown significantly. In fact, in February 2010, it received signals from 305 seismic stations, 258 with wideband three-component sensors. We constructed SNES maps for magnitudes of 1.5, 2, 2.5, and 3, fixing the hypocentral depth at 10 km and the confidence level at 95%. Through the application of the SNES method, we show that the RSNC–INGV provides the best monitoring coverage in the Apennine Mountains with errors that for M 2, are less than 2 and 4 km for epicenter and hypocentral depth, respectively. At M 2.5 this seismic network is capable of constraining earthquake hypocenters to depths of about 150 km for most of the Italian Peninsula. This seismic network provides a threshold of completeness down to M 2 for almost the entire Italian territory.
    Description: Published
    Description: 1213-1232
    Description: 2.5. Laboratorio per lo sviluppo di sistemi di rilevamento sottomarini
    Description: JCR Journal
    Description: reserved
    Keywords: Italian National Seismic Network ; Magnitude of Completeness ; Location Performance ; Seismic Noise ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 21
    Publication Date: 2017-04-04
    Description: We present the first application of a time reverse location method in a volcanic setting, for a family of long-period (LP) events recorded on Mt Etna. Results are compared with locations determined using a full moment tensor grid search inversion and cross-correlation method. From 2008 June 18 to July 3, 50 broad-band seismic stations were deployed on Mt Etna, Italy, in close proximity to the summit. Two families of LP events were detected with dominant spectral peaks around 0.9 Hz. The large number of stations close to the summit allowed us to locate all events in both families using a time reversal location method. The method involves taking the seismic signal, reversing it in time, and using it as a seismic source in a numerical seismic wave simulator where the reversed signals propagate through the numerical model, interfere constructively and destructively, and focus on the original source location. The source location is the computational cell with the largest displacement magnitude at the time of maximum energy current density inside the grid. Before we located the two LP families we first applied the method to two synthetic data sets and found a good fit between the time reverse location and true synthetic location for a known velocity model. The time reverse location results of the two families show a shallow seismic region close to the summit in agreement with the locations using a moment tensor full waveform inversion method and a cross-correlation location method.
    Description: In press
    Description: (11)
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Volcano seismology ; Computational seismology ; Wave propagation ; 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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  • 22
    Publication Date: 2017-04-03
    Description: After an earthquake, rapid, real-time assessment of hazards such as ground shaking and tsunami potential is important for early warning and emergency response. Tsunami potential depends on sea floor displacement, which is related to the length, L, width, W, mean slip, D, and depth, z, of earthquake rupture. Currently, the primary discriminant for tsunami potential is the centroid-moment tensor magnitude, MwCMT, representing the seismic potency LWD, and estimated through an indirect, inversion procedure. The obtained MwCMT and the implied LWD value vary with the depth of faulting, assumed earth model and other factors, and is only available 30 min or more after an earthquake. The use of more direct procedures for hazard assessment, when available, could avoid these problems and aid in effective early warning. Here we present a direct procedure for rapid assessment of earthquake tsunami potential using two, simple measures on P-wave seismograms – the dominant period on the velocity records, Td, and the likelihood that the high-frequency, apparent rupture-duration, T0, exceeds 50-55 sec. T0 can be related to the critical parameters L and z, while Td may be related to W, D or z. For a set of recent, large earthquakes, we show that the period-duration product TdT0 gives more information on tsunami impact and size than MwCMT and other currently used discriminants. All discriminants have difficulty in assessing the tsunami potential for oceanic strike-slip and back-arc or upper-plate, intraplate earthquake types. Our analysis and results suggest that tsunami potential is not directly related to the potency LWD from the “seismic” faulting model, as is assumed with the use of the MwCMT discriminant. Instead, knowledge of rupture length, L, and depth, z, alone can constrain well the tsunami potential of an earthquake, with explicit determination of fault width, W, and slip, D, being of secondary importance. With available real-time seismogram data, rapid calculation of the direct, period- duration discriminant can be completed within 6-10 min after an earthquake occurs and thus can aid in effective and reliable tsunami early warning.
    Description: In press
    Description: 1.1. TTC - Monitoraggio sismico del territorio nazionale
    Description: JCR Journal
    Description: open
    Keywords: Earthquake dynamics ; Earthquake source observations ; Seismic monitoring ; Body waves ; Early warning ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 23
    Publication Date: 2021-11-09
    Description: Il 24 maggio 2011, alle 12.40 UTC, la Rete Sismica Nazionale (RSN) dell’Istituto Nazionale di Geofisica e Vulcanologia (INGV) ha registrato un evento sismico di magnitudo (ML) 3.1 nel distretto sismico1 [Selvaggi et al., 1996] del Montefeltro (in provincia di Forlì-Cesena). Nelle successive due settimane sono stati localizzati dalla Sala di Sorveglianza Sismica della sede romana dell’INGV oltre 600 eventi di cui 13 di ML ≥ 3.0. Otto di questi eventi più energetici sono accaduti entro le prime 16 ore dalla prima scossa. L’evento di maggiore energia si è verificato la notte tra il 24 e il 25 maggio (ore 22.03 UTC del 24 maggio) con una magnitudo pari a ML 3.7 (Tabella 1). Considerando la peculiare evoluzione della sequenza nelle prime 24 ore dal primo evento, la prossimità dell'area epicentrale all’Alta Val Tiberina (AVT nel seguito) dove è attualmente in corso un esperimento sismico passivo [Progetto NOVAT2; Cattaneo et al., 2011; D’Alema et al., 2011] e l’apprensione che stava diffondendosi tra la popolazione, è stato ritenuto opportuno attivare le procedure di risposta ad una emergenza sismica e predisporre un intervento volto a migliorare la copertura strumentale dell'area. Il 25 maggio, in accordo con i colleghi INGV della Sezione di Pisa, dell’Osservatorio di Arezzo [Braun, 2006], della sede di Ancona e della Fondazione Prato Ricerche3, si è proceduto con l'istallazione di una rete sismica temporanea ad integrazione delle stazioni permanenti già presenti in zona. Nella giornata del 27 maggio, due delle stazioni temporanee sono state predisposte per la trasmissione in tempo reale alla Sala di Sorveglianza Sismica di Roma dei dati acquisiti, per migliorare la precisione delle localizzazioni prodotte. Nel contempo, sono stati curati dei comunicati informativi divulgati attraverso il sito web4 dell’Ente, parzialmente inclusi in questo lavoro, per dare una risposta alla popolazione interessata dalla sequenza e fortemente preoccupata dall’intensificarsi della sismicità. Il presente lavoro, la cui redazione è stata completata mentre la sequenza è ancora in corso, vuole essenzialmente descrivere le procedure che vengono attivate all’INGV in risposta ad una emergenza sismica e fornire uno strumento tecnico di supporto alla successiva elaborazione della base dati raccolta nel corso dell'esperimento. Viene quindi presentata una breve introduzione sulle conoscenze sismologiche dell’area interessata dalla sequenza, vengono descritti i comunicati emessi dall’INGV per informare i cittadini e viene descritto l’intervento della rete sismica temporanea, ovvero la tempistica dell'istallazione, la strumentazione utilizzata, e i siti occupati.
    Description: Published
    Description: 1-17
    Description: 1.1. TTC - Monitoraggio sismico del territorio nazionale
    Description: N/A or not JCR
    Description: open
    Keywords: Seismic Monitoring ; Emergency ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 24
    Publication Date: 2017-04-04
    Description: Stress can undergo rapid temporal changes in volcanic environments, and this is particularly true during eruptions. We use two independent methods, coda wave interferometry (CWI) and shear wave splitting (SWS) analysis to track stress related wave propagation effects during the waning phase of the 2002 NE fissure eruption at Mt Etna. CWI is used to estimate temporal changes in seismic wave velocity, while SWS is employed to monitor changes in elastic anisotropy. We analyse seismic doublets, detecting temporal changes both in wave velocities and anisotropy, consistent with observed eruptive activity. In particular, syn-eruptive wave propagation changes indicate a depressurization of the system, heralding the termination of the eruption, which occurs three days later.
    Description: Published
    Description: 1779-1788
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Interferometry ; Seismic anisotropy ; Volcano seismology ; Volcano monitoring ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 25
    Publication Date: 2017-04-04
    Description: In April 1998, a swarm of 1800 microearthquakes near the village of Iznajar (southern Spain) was recorded at the Granada basin short-period seismic network. Focal mechanisms from local P-wave polarities are poorly constrained and cannot characterize the seismotectonics of the series. Here we combine polarity information and multiplet relocation to address this issue. We use waveform cross correlation on P and S arrivals to identify events with highly similar seismograms, group our detections into multiplet clusters, and invert the cross-correlation time delays to obtain precise relative locations. Relative locations have errors of several tens to a few hundreds of meters horizontally and vertically, and define strike and dip of active fault patches with an accuracy of 20°–30°. We introduce the multiplet fault plane orientations into focal mechanism inversion, now yielding mostly well-constrained solutions, in addition to resolving the nodal plane symmetry. We observe mainly north-south left-lateral strike-slip faulting and a few north-northwest–south-southeast normal faulting solutions, illustrating the kinematic complexity of the swarm, and pointing to a local deformation style different from the nearby Granada basin.
    Description: Published
    Description: 3421-3429
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: reserved
    Keywords: Fault plane solution ; Precise location ; Seismic swarm ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 26
    Publication Date: 2017-04-04
    Description: Horizontal-to-vertical spectral ratios using ambient noise (HVNSR) are commonly used in site effects studies. In the practice, many operators assume stability over time of HVNSR and base their analyses on few very short time windows. The availability of a long period of continuous microtremor recording allowed us to analyze three months of data coming from a dense array experiment performed at Cavola, a village in northern Apennines. This condition offers a good opportunity to check the validity of the stability assumption and to investigate variations of the local ambient noise wave-field composition. The Cavola site is characterized by landslide sediments over stiffer materials with a moderate impedance contrast and by a complex morphology. An intense industrial activity in the village contributes to the generation of seismic noise. After identifying this noise source in the time series, we evaluate its effects on HVNSR. The results indicate that the spectral peak of HVNSR varies in amplitude and frequency, posing a warning about stability in time. Analyzing the spectra we identify the anthropic activity as responsible for changes in the composition of the noise wave field. These variations affect HVNSR, including peak frequency and also ground-motion polarization.
    Description: Published
    Description: 1263-1275
    Description: 4.1. Metodologie sismologiche per l'ingegneria sismica
    Description: JCR Journal
    Description: restricted
    Keywords: noise measurements ; Rayleigh waves ; polarization ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring ; 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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  • 27
    Publication Date: 2017-04-04
    Description: IEEE Standard for Local and Metropolitan Area Networks (hereafter IEEE 802.16; online at http://standards.ieee.org/getieee802/802.16.html) is one of the most promising mobile and fixed broadband wireless access technologies for next-generation all-IP networks in the 3.5 GHz band (European spectrum profile). Commonly known as Universal WiMAX (worldwide inter-operability for microwave access), this access technology reaches a high bit rate and covers large areas with a single base station, making it possible to offer connectivity to end users in a cost-effective way. A further useful property of the WiMAX technology is that the transmission can be used both in line-of-sight (LOS) and non-line-of-sight (NLOS) environments, allowing highly feasible communications (WiMAX Forum 2004). Thanks to these features, IEEE 802.16 opens the way to the use of wireless technologies in the environmental monitoring of areas such as seismic and volcanic zones.
    Description: European Community’s Sixth Framework Programme, Contract no. IST-034622-IP
    Description: Published
    Description: 411-419
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: WiMAX ; volcano monitoring ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 28
    Publication Date: 2017-04-04
    Description: L’uso del rumore ambientale nella valutazione della risposta sismica locale sta diventando molto frequente data la sua facile applicabilità e sensibilità alla variazione spaziale della geologia superficiale. Ciò lo rende particolarmente adatto nelle aree urbane, dove la natura delle unità geologiche affioranti è mascherata dagli interventi antropici. Il lavoro descrive i metodi di acquisizione e di trattamento dei dati, utilizzati durante una campagna svoltasi nell'area urbana di Catania.
    Description: Published
    Description: 1-30
    Description: 1.8. Osservazioni di geofisica ambientale
    Description: N/A or not JCR
    Description: open
    Keywords: NOISE ; ACQUISIZIONE ; URBANA ; CATANIA ; 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 ; 05. General::05.01. Computational geophysics::05.01.01. Data processing
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 29
    Publication Date: 2022-06-14
    Description: On 6 April 2009, at 01:32 GMT, an Mw 6.3 seismic event hit the central Apennines, severely damaging the town of L’Aquila and dozens of neighboring villages and resulting in approximately 300 casualties (Istituto Nazionale di Geofisica e Vulcanologia, http://www.ingv.it; MedNet, http://mednet.rm.ingv.it/proce- dure/events/QRCMT/090406_013322/qrcmt.html). This earth- quake was the strongest in central Italy since the devastating 1915 Fucino event (Mw 7.0). The INGV national seismic net- work located the hypocenter 5 km southwest of L’Aquila, 8–9 km deep. Based on this information and on the seismotectonic framework of the region, earthquake geologists traveled to the field to identify possible surface faulting (Emergeo Working Group 2009a, 2009b). The most convincing evidence of pri- mary surface rupture is along the Paganica fault, the geometry of which is consistent with seismological, synthetic aperture radar (SAR) and GPS data. Investigation of other known nor- mal faults of the area, i.e., the Mt. Pettino, Mt. San Franco, and Mt. Stabiata normal faults suggested that these structures were not activated during the April 6 shock (Emergeo Working Group 2009a, 2009b). In this report, we first describe the seismotectonic frame- work of the area, and then we present the field information that supports the occurrence of surficial displacement on the Paganica fault.
    Description: Published
    Description: 940-950
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: open
    Keywords: Surface coseismic ruptures ; Paganica Fault ; earthquake ; 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::04.06.01. Earthquake faults: properties and evolution ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 30
    Publication Date: 2017-04-04
    Description: We have implemented a method based on an unsupervised neural network to cluster the waveforms of very-long-period (VLP) events associated with explosive activity at the Stromboli volcano (southern Italy). Stromboli has several active vents in the summit area producing together more than 200 explosions=day. We applied this method to investigate the relationship between each vent and its associated VLP explosive waveform. We selected 147 VLP events recorded between November and December 2005, when digital infrared camera recordings were available. From a visual inspection of the infrared camera images, we classified the VLPs on the basis of which vent produced each explosion. We then applied the self-organizing map (SOM), an unsupervised neural technique widely applied in data exploratory analysis, to cluster the VLPs on the basis of their waveform similarity. Our analysis demonstrates that the most recurrent VLP waveforms are usually generated by the same vent. Some exceptions occurred, however, in which different waveforms are associated with the same vent, as well as different vents generating similar waveforms. This suggests that the geometry of the upper conduit-vent system plays a role in shaping the recurring VLP events, whereas occasional modest changes in the source process dynamics produce the observed exceptions.
    Description: Published
    Description: 2449–2459
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Stromboli ; Maps ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 05. General::05.01. Computational geophysics::05.01.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 31
    Publication Date: 2017-04-04
    Description: In this note, we investigate the characteristics of ambient noise cross-correlations for station pairs in northern Italy, considering the secondary microseism bandwidth (0.1-0.6 Hz). The preliminary analysis that we performed exploiting the available continuous recording in the investigated area, agrees with the recent results of Pedersen et al. (2007): the directionality of the noise signal cannot be disregarded when the group velocity is estimated in the range 0.1-0.6 Hz and the selection of the path orientation for tomography must be carefully performed. In particular, while the favourable directions with respect to microseisms generated along the Atlantic coasts of France, Norway and British Islands cover a quite wide azimuthal range (from about 270N to 5N), allowing us to reliably estimate the fundamental mode Rayleigh group velocity for paths in the Alps (about 2.7 km/s), more care must be taken when the microseisms are generated in the Mediterranean Sea. In that case, different locations of the generating areas of microseisms could provide biased estimates of the group velocity due to differences between the true and the apparent velocity of propagation between the stations.
    Description: Published
    Description: 1389-1398
    Description: 1.1. TTC - Monitoraggio sismico del territorio nazionale
    Description: JCR Journal
    Description: reserved
    Keywords: microseisms ; ambient noise ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 32
    Publication Date: 2017-04-04
    Description: The Campi Flegrei (southern Italy) is one of the most active calderas in the world. This caldera is characterized by episodes of slow vertical ground movement, called bradyseism. With several hundred thousand people living within its borders, this area is in a high-risk category should there be an eruption. The seismological monitoring system in the Campi Flegrei is based on nine seismic stations, eight of which are equipped with short-period seismometers (1 Hz), and one with a broadband seismometer (60 sec–50 Hz). While all of the seismic stations are located on land, part of the seismic activity occurs in the undersea area of the Pozzuoli Gulf (Campi Flegrei), where there are no seismic stations. This gap in the data coverage produces a biased and incomplete image of the volcanic area.We carried out an experiment in the Pozzuoli Gulf with the installation of two broadband seismic stations on the seafloor with remote and continuous data acquisition for a duration of 31 days between January and March 2005. Using the data acquired, we have computed the power spectral density (PSD) to characterize the background seismic noise, and to evaluate the true noise variation, we have generated the seismic noise probability density functions from the computed PSD curves. The results of our analysis show that the broadband seismic noise is high when compared with the Peterson noise model (land model), but for periods less than 0.3 sec, the seismic noise on the seafloor is lower than the recordings on land over the same period range. The last bradyseismic crisis (1982–1984) highlights the importance of this frequency range, where most of the spectral content of the recorded earthquakes was observed. Finally, we evaluate the detection threshold of a new seismic station located on the seafloor of the Campi Flegrei caldera considering the characteristics of the local seismicity. This analysis shows that the detection threshold for the sea-floor stations (Mw ∼ 0:2) is less than that for land stations (Mw ∼ 0:8).
    Description: Published
    Description: 2962–2974
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Campi Flegrei Caldera ; Sea-Floor and On-Land Seismic ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 33
    Publication Date: 2020-11-20
    Description: Il presente lavoro è costituito dalla raccolta sistematica delle indagini macrosismiche eseguite in occasione dei terremoti più energetici verificatisi in Sicilia orientale dal Gennaio 2002 al Dicembre 2005. Esso rappresenta l’estensione, agli anni più recenti, della compilazione effettuata per il periodo 1999-2001 [Azzaro et al., 2002], e più in generale è inserita nel contesto delle attività di pronto intervento macrosismico effettuate regolarmente in ambito regionale dal 1988. L’esecuzione di rilievi in occasione di eventi sismici significativi è una prassi ormai consolidata nelle attività di monitoraggio dell’INGV, che recentemente ha istituito a tal fine il gruppo di lavoro denominato QUEST (QUick Earthquake Survey Team, DP n° 44 del 25/02/2004). I dati raccolti assolvono ad una duplice funzione: 1) nell’immediatezza di un evento sismico, a definire il quadro degli effetti a supporto degli interventi di Protezione Civile e della Comunità Scientifica; 2) a risolvere lacune e problemi interpretativi dei terremoti del passato attraverso il confronto con gli effetti macrosismici degli eventi attuali. La raccolta sistematica di dati macrosismici anche nel caso di eventi di bassa magnitudo, che interessano estensioni areali limitate come quelle etnee, è comunque importante per l’implementazione di banche dati e cataloghi macrosismici sia a livello locale che nazionale. Nel primo caso è stato aggiornato il catalogo macrosismico dei terremoti etnei [Azzaro et al., 2000], recentemente reso disponibile anche su Internet. Nel secondo caso, la più recente versione del catalogo parametrico dei terremoti italiani [Gruppo di Lavoro CPTI, 2004] utilizzata per la redazione della nuova mappa di pericolosità sismica del territorio nazionale (Ordinanza PCM 3274 del 20/03/2003), incorpora i dati dei terremoti siciliani al di sopra della soglia del danno pubblicati in Azzaro et al. [2002, 2003]. I rilievi macrosismici di seguito riportati sono relativi a tutti i terremoti oltre la soglia del danno verificatisi nel periodo considerato, ovvero a quegli eventi che sono stati avvertiti in modo significativo dalla popolazione (Figura 1). In larga parte si tratta di eventi di area etnea che, soprattutto nel corso del 2002, hanno provocato effetti macrosismici di rilievo. Tra i terremoti regionali riportati, non è incluso il terremoto di Palermo del 2002 per il quale è disponibile uno studio specifico [Azzaro et al., 2003].
    Description: Published
    Description: 1-62
    Description: 1.11. TTC - Osservazioni e monitoraggio macrosismico del territorio nazionale
    Description: N/A or not JCR
    Description: open
    Keywords: NONE ; Sicilia ; terremoti ; macrosismica ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring ; 05. General::05.02. Data dissemination::05.02.02. Seismological data
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  • 34
    Publication Date: 2017-04-04
    Description: The Colfiorito Basin is a small intramountain depression in the southern section of the Northern Apennine chain that is filled with Quaternary alluvial deposits. The presence of soft alluvial deposits has significantly influenced the level of local damage that was caused by two major earthquakes (ML 5.6 and 5.8) belonging to the swarm that started in September 1997. To verify the effects of the basin structure on the predominant frequency of seismic motion, ambient noise measurements were carried out in the Colfiorito Basin during two experiments in May and July of 2002. The horizontal-to-vertical spectral ratios (HVSRs) were calculated for data collected at four profiles in the basin. Array techniques were applied to determine the wave types that composed the noise, to estimate their apparent velocity and azimuth of propagation, and to calculate a velocity-dispersion curve from which a velocity-depth structure was derived. The data analysis shows a high amplification in the HVSR at low frequency. This feature is common to most of the sites, including the reference site, and it is interpreted as being due to weather disturbances. The peak frequencies of the spectral ratio calculated at the sites located in the center of the basin coincide with the theoretically estimated resonance frequencies. The arrayaveraged HVSR calculated for the array located in the middle of the plain has a pronounced peak at 0.9 Hz. This corresponds to the peak of the amplification function calculated on the basis of the velocity model deduced from the dispersion analysis. The HVSR method is instead unsuitable for the prediction of the resonance frequencies of sediments in the sites where strong lateral variations of basement topography are present. We measured apparent velocities in the range of 0.3–0.8 km/sec by applying f-k methods to array recordings. These values are compatible with the predominance of surface waves in the noise, as also confirmed by polarization analysis. Both Rayleigh and Love waves are present in the background seismic noise. The results obtained by applying the spatial autocorrelation method to the vertical component of the ground motion recorded at a 240-m-wide circular array deployed in the middle of the basin revealed the presence of Rayleigh waves, and f-k methods combined with polarization techniques revealed the presence of polarized Love waves. The wave-field analysis indicates two main propagation directions: the first is around N100 E in the frequency band of 1.0–2.0 Hz; this radiation can be interpreted as being generated at the east-southeast step borders of the basin. The second main direction is around N300 E in the frequency band of 2.0–3.0 Hz; its source may be a 180-m-deep depression located at the southwest corner of the basin.
    Description: Published
    Description: 490–505
    Description: reserved
    Keywords: NONE ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
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  • 35
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    Istituto Nazionale di Geofisica e Vulcanologia
    Publication Date: 2017-04-04
    Description: Published
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: open
    Keywords: rock physics, geomechanics, thermo-hydro-mechanical coupling, natural hazards ; 04. Solid Earth::04.01. Earth Interior::04.01.04. Mineral physics and properties of rocks ; 04. Solid Earth::04.01. Earth Interior::04.01.05. Rheology ; 04. Solid Earth::04.04. Geology::04.04.06. Rheology, friction, and structure of fault zones ; 04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk ; 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book
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  • 36
    Publication Date: 2017-04-04
    Description: We investigate the complex propagation of seismic waves beneath the Campi Flegrei caldera, Italy, using multichannel recordings of artificial explosions. The sources consisted of air gun explosions shot in the Gulf of Pozzuoli at offsets ranging between 3 and 7 km. A multichannel recording device was deployed in the Solfatara crater and consisted of ten vertical-component and two three-component short-period seismometers with a maximum aperture of about 150 m. The zero-lag correlation (ZLC) technique was adopted to estimate horizontal slowness and backazimuth of coherent waves crossing the array. For sources located in the northern sector of the Gulf, with maximum offset 5 km, ray parameters and backazimuths are in agreement with those predicted for the 1D velocity model used for routine locations. For sources at offsets larger than approximately 5 km, the ZLC curves depict prominent maxima associated with a secondary phase propagating with a lower velocity than the first-arrival P wave. Using finite-difference synthetic seismograms generated for a 2D realistic velocity model, we explain these late arrivals in terms of a lateral velocity variation located at depths of about 1 km. Such discontinuity would correspond to a positive V (sub p) anomaly imaged by a recent 3D tomographic study, and interpreted as the submerged southern rim of Campi Flegrei caldera collapsed during the explosive eruption of 12 ky B.P. The small spacing among adjacent shot points allowed simultaneous wave-field decomposition at the source and receiver arrays. Using a modified version of the double-beam method, we retrieve the independent variation of horizontal slowness at both the source and receiver regions. For both cases, we found azimuthal deviations as large as 50 degrees with respect to the great circle path. At the source region, these discrepancies may be interpreted in terms of ray bending at the interface of the aforementioned positive anomaly. At the receiver array, the observed anomalies may be attributed to either velocity variations marking the Solfatara crater rim, or to a near-receiver, low-velocity body whose position would coincide with negative gravimetric anomalies and a high V (sub p) /V (sub s) ratio region inferred by independent geophysical and seismological studies.
    Description: Published
    Description: 440-456
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: tomography ; campi flegrei ; wavefield modeling ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 37
    Publication Date: 2017-04-04
    Description: The properties of the tremor wave field at Stromboli are analyzed using data from small-aperture arrays of short-period seismometers deployed on the north flank of the volcano. The seismometers are configured in two semi-circular arrays with radii of 60 and 150 m and a linear array with length of 600 m. The data are analyzed using a spatiotemporal correlation technique specifically designed for the study of the stationary stochastic wave field of Rayleigh and Love waves generated by volcanic activity and by scattering sources distributed within the island. The correlation coefficients derived as a function of frequency for the three components of motion clearly define the dispersion characteristics for both Rayleigh and Love waves. Love and Rayleigh waves contribute 70% and 30%, respectively, of the surface-wave power. The phase velocities of Rayleigh waves range from 1000 m/sec at 2 Hz to 350 m/sec at 9 Hz, and those for Love waves range from 800 to 400 m/sec over the same frequency band. These velocities are similar to those measured near Puu Oo on the east rift of Kilauea Volcano, Hawaii, although the dispersion characteristics of Rayleigh waves at Stromboli show a stronger dependence on frequency. Such low velocities are consistent with values expected for densely cracked solidified basalt. The dispersion curves are inverted for a velocity model beneath the arrays, assuming those dispersions represent the fundamental modes of Rayleigh and Love waves.
    Description: Published
    Description: 653-666
    Description: reserved
    Keywords: volcanic tremor ; array ; velocity structure ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 38
    Publication Date: 2017-04-04
    Description: In this article we report on the implementation of an automatic system for discriminating landslide seismic signals on Stromboli island (southern Italy). This is a critical point for monitoring the evolution of this volcanic island, where at the end of 2002 a violent tsunami occurred, triggered by a big landslide. We have devised a supervised neural system to discriminate among landslide, explosion-quake, and volcanic microtremor signals. We first preprocess the data using a compact representation of the seismic records. Both spectral features and amplitude-versus-time information have been extracted from the data to characterize the different types of events. As a second step, we have set up a supervised classification system, trained using a subset of data (the training set) and tested on another data set (the test set) not used during the training stage. The automatic system that we have realized is able to correctly classify 99% of the events in the test set for both explosion-quake/ landslide and explosion-quake/microtremor couples of classes, 96% for landslide/ microtremor discrimination, and 97% for three-class discrimination (landslides/ explosion-quakes/microtremor). Finally, to determine the intrinsic structure of the data and to test the efficiency of our parameterization strategy, we have analyzed the preprocessed data using an unsupervised neural method. We apply this method to the entire dataset composed of landslide, microtremor, and explosion-quake signals. The unsupervised method is able to distinguish three clusters corresponding to the three classes of signals classified by the analysts, demonstrating that the parameterization technique characterizes the different classes of data appropriately.
    Description: Published
    Description: 1230-1240
    Description: reserved
    Keywords: NONE ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
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    Type: article
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  • 39
    Publication Date: 2017-04-04
    Description: The new Italian National Seismic Network (INSN) is a dense network of broadband stations deployed for monitoring Italian seismicity. The network consists of 250 stations with a typical station spacing of !40 km. Earthquake early warning is the rapid detection of an event in progress, assessment of the hazard it poses, and transmission of a warning ahead of any significant ground motion. We explore the potential for using the INSN real-time network for the purpose of earthquake early warning. We run the ElarmS early warning methodology off-line using a data set of more than 200 events with magnitudes between 2.5 and 6.0. A scaling relation for magnitude determination from the dominant period of the first seconds of signal following the P onset is developed from the data set. The standard deviation in the magnitude estimates using this approach is 0.4 magnitude units, and all event magnitude estimates are within !0:75 magnitude units of the true magnitude. Given the existing distribution of seismic stations it takes an average of 10 sec after event initiation before the P wave has been detected at four stations. If we require a detection at four stations before issuing the first alert, then the blind zone, within which no warning would be available, has a radius of !37 km. The ElarmS methodology can provide a warning earlier than this but with a greater uncertainty. An assessment of past damaging earthquakes across Italy shows that applying ElarmS with the existing seismic network could provide warning to population centers in repeats of past events. For example, in a repeat of the 1980 Irpinia earthquake Naples could receive an !15- sec warning. The variations in the size of the blind zone and warning times for different regions can be used as a guide to selecting strategic locations for future station deployments.
    Description: Published
    Description: 495-503
    Description: 1.1. TTC - Monitoraggio sismico del territorio nazionale
    Description: JCR Journal
    Description: reserved
    Keywords: Early Warning ; Earthquake Location ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 40
    Publication Date: 2017-04-04
    Description: With the aim to find a more objective way to detect seismic families, we applied a series of successive steps to constrain the results of a waveform similarity analysis. The evaluation of similarity was carried out on the waveforms recorded in the period 1999–2003 by the stations operating in the Garfagnana area, located in northern Tuscany (Italy). The algorithm is based on the cross-correlation technique applied in a process that overcomes the limit of one order of magnitude between events to be compared through a bridging technique. In practice, if two couples of events (A, B) and (B, C), each exceeding the correlation threshold, share a common quake (B), then all three events are attributed to the same family even if the match between A and C is below a value chosen as a reference for similarity. To avoid any subjective choice of threshold for cross-correlation values, the results from the computation algorithm are submitted to a routine that gives increasing reliability to them if they are confirmed by the three components of the seismogram and if the number of families detected by each station is confirmed by more recordings. This latter constraint is made possible by the geometry of the recording network, with interdistances between stations of the order of 40–50 km. The process finally leads to the recognition of 27 families detected and confirmed by, on average, 3 stations that represent 40% of the recording capabilities. Since the performances of the recording network have been very odd in the past, especially in the early years of operation, the reliability of the detection is much higher, as in most cases the stations that detected the families were the only ones to be effectively recording. The methodology proved to be more efficient than other methods applied in the past; moreover, the results could be probably improved even more if, instead of doing a one-run process, it would be borne as a trial-and-error approach.
    Description: Published
    Description: 1903-1915
    Description: JCR Journal
    Description: reserved
    Keywords: Seismicity ; multiplets ; seismic families ; seismic sequences ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring ; 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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  • 41
    Publication Date: 2017-04-04
    Description: A small aperture quadripartite seismic array was installed on the south-east flanks of Mt. Vesuvius about 1 km far from the crater axis, in order to improve the seismic monitoring of this active volcano. The array has the following main purposes: i) to discriminate natural-source generated signals by artificial-source-generated signals; ii) to detect and track the source of possible Long Period (LP) events; iii) to detect coherent phases in the low frequency noise that may be related to magma movements (tremor insurgence). In addition, the array greatly helps in locating the seismic signals produced by blasts (both in land and sea), allowing a fast discrimination of possible natural long period (LP) quakes. The array is also an useful tool for retrieving the kinematic properties of the wavefield associated to volcano-tectonic (VT) earthquakes (more than 99% of the whole natural seismicity) and to all the other transients which are routinely observed(landslides, artificial blasts). We also use the array to investigate if correlated signals are present in the background noise (insurgence of volcanic tremor). The main result obtained during this first year of observation is that one LP was clearly recognized in the background seismicity at Mt. Vesuvius.
    Description: Published
    Description: 344-355
    Description: open
    Keywords: Volcano monitoring ; Array techniques ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 42
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    3
    In:  Computers and Geosciences, Münster, 3, vol. 28, no. 45, pp. 309-326, pp. L11609, (ISBN 0-471-26610-8)
    Publication Date: 2002
    Keywords: Inversion ; Data analysis / ~ processing ; Non-linear effects ; Discrimination ; C&G
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  • 43
    facet.materialart.
    Unknown
    Wiley
    In:  Mathematical Methods for Digital Computers, Volume 1, Sapporo, Japan, Wiley, vol. 17, no. 16, pp. 211-236, (ISBN 0080419208)
    Publication Date: 1967
    Keywords: Inversion
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  • 44
    facet.materialart.
    Unknown
    Wiley
    In:  Mathematische Methoden für Digitalrechner, Sapporo, Japan, Wiley, vol. 1, no. 16, pp. 106-126, (ISBN 0080419208)
    Publication Date: 1967
    Keywords: Inversion
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