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  • 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring  (32)
  • 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous
  • Volcano seismology
  • INGV  (34)
  • Wiley  (5)
  • American Chemical Society (ACS)
  • American Institute of Physics
  • Nature Publishing Group
Collection
Keywords
Years
  • 1
    Publication Date: 2017-04-04
    Description: In open conduit volcanoes, volatile-rich magma continuously enters into the feeding system nevertheless the eruptive activity occurs intermittently. From a practical perspective, the continuous steady input of magma in the feeding system is not able to produce eruptive events alone, but rather surplus of magma inputs are required to trigger the eruptive activity. The greater the amount of surplus of magma within the feeding system, the higher is the eruptive probability.Despite this observation, eruptive potential evaluations are commonly based on the regular magma supply, and in eruptive probability evaluations, generally any magma input has the same weight. Conversely, herein we present a novel approach based on the quantification of surplus of magma progressively intruded in the feeding system. To quantify the surplus of magma, we suggest to process temporal series of measurable parameters linked to the magma supply. We successfully performed a practical application on Mt Etna using the soil CO2 flux recorded over ten years.
    Description: Published
    Description: 30471
    Description: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Description: 5V. Sorveglianza vulcanica ed emergenze
    Description: JCR Journal
    Description: restricted
    Keywords: eruptive potential ; eruptive probability ; open conduit volcanoes ; Etna ; Soil CO2 flux ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.08. Risk::05.08.01. Environmental risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
    Publication Date: 2017-04-04
    Description: Over fifty eruptive episodes with Strombolian activity, lava fountains, and lava flows occurred at Mt Etna volcano between 2006 and 2013. Namely, there were seven paroxysmal lava fountains at the South-East Crater in 2007-2008 and 46 at the New South-East Crater between 2011 and 2013. Lava emissions lasting months affected the upper eastern flank of the volcano in 2006 and 2008-2009. Effective monitoring and forecast of such volcanic phenomena are particularly relevant for their potential socio-economic impact in densely populated regions like Catania and its surroundings. For example, explosive activity has often formed thick ash clouds with widespread tephra fall able to disrupt the air traffic, as well as to cause severe problems at infrastructures, such as highways and roads. Timely information about changes in the state of the volcano and possible onset of dangerous eruptive phenomena requires efficacious surveillance methods. The analysis of the continuous background seismic signal, the so-called volcanic tremor, turned out of paramount importance to follow the evolution of volcanic activity [e.g., Alparone et al., 2003; Falsaperla et al., 2005]. Changes in the state of the volcano as well as in its eruptive style are usually concurrent with variations of the spectral characteristics (amplitude and frequency) of tremor. The huge amount of digital data continuously acquired by INGV’s broadband seismic stations every day makes a manual analysis difficult. In order to tackle this problem, techniques of automatic classification of the tremor signal are applied. In a comparative study, the robustness of different methods for the identification of regimes in volcanic activity were examined [Langer et al., 2009]. In particular, Langer et al. [2011] applied unsupervised classification techniques to the tremor data recorded at one station during seven paroxysmal episodes in 2007-2008. Their results revealed significant changes in the pattern classification well before the onset of the eruptive episodes. This evidence led to the development of specific software packages, such as the program KKAnalysis [Messina and Langer, 2011], a software that combines an unsupervised classification method (Kohonen Maps) with fuzzy cluster analysis. The operational characteristics of these tools - fail-safe, robustness with respect to noise and data outages, as well as computational efficiency - allowed on-line processing at the operative centre of the INGV-Osservatorio Etneo in 2010 and the identification of criteria for automatic alarm flagging. The system is hitherto one of the main automatic alerting tools to identify impending eruptive events at Etna. The software carries out the on-line processing of the new data stream coming from two seismic stations, merged with reference datasets of past eruptive episodes. In doing so, results obtained for new data are immediately compared to previous eruptive scenarios. Given the rich material collected in recent years, we are able to apply the alert system to eleven stations at different elevations (1200-3050 m) and distances (1-8 km) from the summit craters. Critical alert parameters were empirically defined to obtain an optimal tuning of the alert system for each station. To verify the robustness of this new, multistation alert system, a dataset encompassing about eight years of continuous seismic records (since 2006) was processed automatically using KKAnalysis and collateral software off-line. Then, we analyzed the performance of the classifier in terms of timing and spatial distribution of the stations. We also investigated the performance of the new alert system based on KKAnalysis in case of activation of whatever eruptive centre. Intriguing results were obtained in 2010 throughout periods characterized by the renewal of volcanic activity at Bocca Nuova-Voragine and North-East Crater, and in the absence of paroxysmal phenomena at South-East Crater and New South-East Crater. Despite the low-energy phenomena reported by volcanologists (i.e., degassing, low-to moderate explosions), the triggered alarms demonstrate the robustness of the classifier and its potential: i) to identify even subtle changes within the volcanic system using tremor, and ii) to highlight the activation of a single eruptive centre, even though different from the one for which the classifier was initially tested. It is worth noting that in case of activation of weak sources, the successful performance of the classifier depends upon the general level of signals originating from other sources in that specific time span.
    Description: Published
    Description: Nicolosi (Catania, Italy)
    Description: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Description: open
    Keywords: Etna, Volcanic tremor ; Volcano monitoring, Pattern recognition ; Self Organizing Map, Fuzzy clustering ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 05. General::05.01. Computational geophysics::05.01.01. Data processing
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Oral presentation
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  • 3
    Publication Date: 2017-04-04
    Description: In this paper, we describe the 1809 eruption of Mt. Etna, Italy, which represents one historical rare case in which it is possible to observe details of the internal structure of the feeder system. This is possible thanks to the presence of two large pit craters located in the middle of the eruptive fracture field that allow studying a section of the shallow feeder system. Along the walls of one of these craters, we analysed well-exposed cross sections of the uppermost 15–20 m of the feeder system and related volcanic products. Here, we describe the structure, morphology and lithology of this portion of the 1809 feeder system, including the host rock which conditioned the propagation of the dyke, and compare the results with other recent eruptions. Finally, we propose the dynamic model of the magma behaviour inside a laterally-propagating feeder dyke, demonstrating how this dynamic triggered important changes in the eruptive style (from effusive/Strombolian to phreatomagmatic) during the same eruption. Our results are also useful for hazard assessment related to the development of flank eruptions, potentially the most hazardous type of eruption from basaltic volcanoes in densely urbanized areas, such as Mt. Etna.
    Description: Published
    Description: 1-11
    Description: 2T. Tettonica attiva
    Description: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Description: 3V. Dinamiche e scenari eruttivi
    Description: 4V. Vulcani e ambiente
    Description: 6A. Monitoraggio ambientale, sicurezza e territorio
    Description: N/A or not JCR
    Description: open
    Keywords: feeder dyke ; basaltic volcanoes ; flank eruptions ; Etna ; volcanic hazards ; sill ; volcanic rift ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.04. Thermodynamics ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 4
    Publication Date: 2017-04-04
    Description: Mt. Etna is permanently active requiring a continuous data acquisition a multidisciplinary monitoring system where huge data masses accumulate and pose severe difficulties of interpretation. Therefore the INGV staff has developed a number of software tools for data mining, aiming at identifying structures in the data which can be related to the volcanic activity and furnish criteria for the definition of alert systems. We tackle the problem by applying methods of clustering and classification. We identify data groups by defining a measure of similarity or distance. Data groups may assume various shapes, once forming convex clouds once complex concave bodies. The tool “KKAanalysis” is a basket of clustering methods and forms the backbone of the tremor-based automatic alarm system of INGV-OE. It exploits both SOM and Fuzzy Clustering. Besides seismic data the concept has been applied to petrochemic data as well as in a combined analysis of gas-emission data and seismic data. The software “DBSCAN” focuses on density-based clustering that allows discovering clusters with arbitrary shape. Here, clusters are defined as dense regions of objects in the data space separated by regions of low density. In DBSCAN a cluster grows guaranteeing that the density within a group of objects exceeds some threshold. In the context of volcano monitoring the method is particularly promising in the recognition of ash particles as they have a rather irregular shape. The “MOTIF” software allows identifying typical wave forms in time series. It overcomes shortages of methods like cross- correlation, which entail a high computational effort. MOTIF on the other hand can recognize non-similarity of two patterns on a small number of data points without going through the whole length of the data vectors. The development includes modules for feature extraction and post-processing verifying the validity of the results obtained by the classifiers.
    Description: Published
    Description: Nicolosi (Catania, Italy)
    Description: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Description: open
    Keywords: Etna, Data mining ; Self Organizing Map, Clustering methods ; Pattern classification ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 05. General::05.01. Computational geophysics::05.01.01. Data processing ; 05. General::05.01. Computational geophysics::05.01.02. Cellular automata, fuzzy logic, genetic alghoritms, neural networks ; 05. General::05.01. Computational geophysics::05.01.05. Algorithms and implementation
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Poster session
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  • 5
    Publication Date: 2017-04-04
    Description: Timely identification of changes in the state of volcanoes and onset of potentially dangerous eruptive phenomena requires efficacious surveillance methods. In the case of an active volcano like Mt Etna, the continuous background seismic signal called volcanic tremor is of paramount importance. The huge amount of continuously acquired digital data entails the necessity of data reduction and parameter extraction. For this purpose, techniques of automatic analysis of volcanic tremor were applied by INGV for the real time monitoring of this signal. We checked the possibility to identify regimes of volcanic activity based on pattern classification of volcanic tremor. A specific software named “KKAnalysis” was developed. It combines various unsupervised classification methods (Kohonen Maps and fuzzy cluster analysis) and forms the backbone of an automatic alert system at INGV-OE. Besides its near real time application, it can be operated off-line, allowing an efficient a-posteriori processing of data and tuning of the alarm criteria to match specific needs of sensitivity and robustness. An ongoing development of this tool will allow us to include a large number of seismic stations in a multistation-alarm system. The new system will be more robust in case of failure of single sensors, and will achieve a better coverage of the various eruptive craters. In an off-line test, we exploited a dataset covering eight years of seismic records, and analysed the performance of the new system in terms of “trigger timing” and spatial distribution of the stations. Intriguing results were obtained throughout periods of renewal of volcanic activity at Bocca Nuova-Voragine and North East Crater, and in the absence of paroxysmal phenomena at South East Crater and New South East Crater.
    Description: Published
    Description: Nicolosi (Catania, Italy)
    Description: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Description: open
    Keywords: Etna, Volcanic tremor ; Self Organizing Map, Fuzzy clustering ; Volcano monitoring, Pattern recognition ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 05. General::05.01. Computational geophysics::05.01.01. Data processing
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Poster session
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  • 6
    Publication Date: 2020-07-07
    Description: In questo lavoro viene descritta l’installazione di una rete mobile nell’area dei Monti Nebrodi in seguito all’evento del 23-06-2011 di Ml = 4.6 e come tale intervento ha contribuito al miglioramento della localizzazione delle sorgenti sismiche soprattutto nella determinazione della profondità degli eventi. Verranno anche presentati i risultati delle localizzazioni ottenute attraverso l’integrazione dei dati acquisiti durante questa campagna, con quelli della rete sismica permanente dell’INGV-Osservatorio Etneo ( INGV -OE).
    Description: Istituto Nazionale di Geofisica e Vulcanologia
    Description: Published
    Description: 1-24
    Description: 4IT. Banche dati
    Description: N/A or not JCR
    Description: open
    Keywords: Rete Sismica Mobile ; Nebrodi ; Sciame ; Localizzazione ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics ; 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
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 7
    Publication Date: 2017-04-04
    Description: Improving lava flow hazard assessment is one of the most important and challenging fields of volcanology, and has an immediate and practical impact on society. Here, we present a methodology for the quantitative assessment of lava flow hazards based on a combination of field data, numerical simulations and probability analyses. With the extensive data available on historic eruptions of Mt. Etna, going back over 2000 years, it has been possible to construct two hazard maps, one for flank and the other for summit eruptions, allowing a quantitative analysis of the most likely future courses of lava flows. The effective use of hazard maps of Etna may help in minimizing the damage from volcanic eruptions through correct land use in densely urbanized area with a population of almost one million people. Although this study was conducted on Mt. Etna, the approach used is designed to be applicable to other volcanic areas.
    Description: This work was developed within the framework of TecnoLab, the Laboratory for Technological Advance in Volcano Geophysics organized by INGV-CT, DIEES-UNICT, and DMI-UNICT.
    Description: Published
    Description: 3493
    Description: 1V. Storia e struttura dei sistemi vulcanici
    Description: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Description: 3V. Dinamiche e scenari eruttivi
    Description: 4V. Vulcani e ambiente
    Description: 6A. Monitoraggio ambientale, sicurezza e territorio
    Description: 3IT. Calcolo scientifico e sistemi informatici
    Description: JCR Journal
    Description: restricted
    Keywords: Lava flow hazard ; Etna ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 05. General::05.01. Computational geophysics::05.01.99. General or miscellaneous ; 05. General::05.02. Data dissemination::05.02.99. General or miscellaneous ; 05. General::05.08. Risk::05.08.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 8
    Publication Date: 2013-04-18
    Description: Twenty-five lava fountains occurred on Mt. Etna from January 2011 to April 2012. In summer 2012 volcanic activity resumed in a milder form within the Bocca Nuova crater, before it came to an essential halt in August 2012. All these unrests offer rich material for testing automatic procedures of data processing and alert systems, running 24/7, in the context of volcano surveillance. We focus on the seismic background radiation – volcanic tremor – which plays a key role in the monitoring of Mt. Etna. Since 2006 a multistation alert system has been established in the INGV operative centre of Catania exploiting STA/LTA ratios. Besides, also the spectral characteristics of the signal, which change correspondingly to the type of volcanic activity, can be exploited for warning purposes. Here we apply Self Organizing Maps and Fuzzy Clustering which offer an efficient way to visualize signal characteristics and its development with time. All these techniques allow to identify early stages of eruptive events, and automatically flag a critical status before this becomes evident in conventional monitoring techniques. Changes of tremor characteristics are related to the position of the source of the signal. The location of the sources exploits the distribution of the amplitudes across the seismic network. The locations were extremely useful for warning, throughout both the flank eruption in 2008 as well as the 2011 lava fountains, during which a clear migration of tremor sources towards the eruptive centres could be noticed in advance. The location of the sources completes the picture of an imminent volcanic unrest, and corroborates early warnings flagged by the changes of signal characteristics. Real time data processing requires computational efficiency, robustness of the methods and stability of data acquisition. The amplitude based multi-station approach is not sensitive to the failure of single stations and therefore offers a good stability. The single station approach, exploiting unsupervised classification techniques, limits logistic efforts, as only one or few key stations are necessary. Both strategies have proven to be insensitive to disturbances (undesired transients like earthquakes, noise, short gaps in the continuous data flow). False alarms were not encountered so far. Stable data acquisition and processing come with a properly designed data storage solution. The reliability of data storage and its access is a critical issue. A cluster architecture has been realized for failover protection, including a Storage Area Network system, which allow easy data access following predefined user policies. We present concepts of the software architectures deployed at INGV Osservatorio Etneo in order to implement this tremor-based multi approach system. We envisage the integration of seismic data and those originating from other scientific fields (e. g., volcano imagery, geochemistry, deformation, gravity, magneto-telluric). This will facilitate cross-checking of evidences encountered from the single data streams, in particular allow their immediate verification with respect to ground truth.
    Description: Published
    Description: Nicolosi (Catania, Italy)
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: 5.6. TTC - Attività di Sala Operativa
    Description: open
    Keywords: Etna, Volcanic tremor ; Volcano monitoring, Pattern recognition ; Self Organizing Map, Fuzzy clustering ; Data acquisition ; 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::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.01. Computational geophysics::05.01.01. Data processing ; 05. General::05.01. Computational geophysics::05.01.04. Statistical analysis
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Oral presentation
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  • 9
    Publication Date: 2021-05-12
    Description: In questo lavoro si presentano i risultati di uno studio sulle caratteristiche del rumore sismico in prossimità del rilevatore di onde gravitazionali VIRGO (Cascina, Pisa), con particolare riferimento alle vibrazioni associate all’azione di un vicino parco eolico. La valutazione delle componenti spettrali del rumore verosimilmente indotte dagli aerogeneratori è stata effettuata mediante (i) Misure dirette alla base di una turbina, (ii) Correlazione fra le ampiezze spettrali del rumore e la velocità del vento; (iii) Determinazione delle proprietà direzionali da misure multicanale, (iv) Misura dell’attenuazione del segnale con la distanza dal parco eolico. Il disturbo provocato dagli aerogeneratori è particolarmente energetico alla frequenza di 1.7 Hz e, in particolari condizioni, è stato osservato fino a distanze di 11 km dal Parco Eolico. Il decadimento spaziale delle ampiezze ha un andamento complesso, che può essere interpretato in termini di una combinazione fra onde superficiali e onde di volume rifratte ad un’interfaccia profonda (~800 m) fra i sedimenti plio-pleistocenici ed i calcari Miocenici. La risposta locale nei dintorni dell’interferometro è stata investigata utilizzando la tecnica dei rapporti spettrali H/V. Si sono così evidenziate due bande di amplificazione imputabili ad effetti di risonanza legati alla geologia a scala locale: il primo intorno alla frequenza di 0.35 Hz, il secondo fra 0.7 e 2.0 Hz. Entrambi i picchi risultano essere essenzialmente omogenei in tutta l’area di studio, a conferma della sostanziale uniformità della struttura geologica.
    Description: Published
    Description: 1-30
    Description: 1.1. TTC - Monitoraggio sismico del territorio nazionale
    Description: N/A or not JCR
    Description: open
    Keywords: Seismic Noise ; Array Seismology ; Gravity Waves ; 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)
    Type: article
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  • 10
    Publication Date: 2017-04-04
    Description: In questo lavoro viene descritto il complesso sistema di acquisizione dati della RSM [vedi D’Alema et al., 2011 - in questo volume], costituita da 58 stazioni collegate in tempo reale e 13 stazioni dial-up. I dati delle stazioni in tempo reale sono acquisiti con il programma Seiscomp31; la detezione degli eventi sismici viene eseguita con il programma Earthworm ed infine l’analisi e l’interpretazione degli eventi viene effettuata attraverso il programma SacPicker di Daniele Spallarossa [vedi Spallarossa, 2011 - in questo volume]. La parte di rete dial-up è basata sul sistema Lennartz Mars882 ed è configurata in modo autonomo dalla rete in tempo reale. I dati delle due reti vengono successivamente uniti in un unico dataset ai fini di una interpretazione interattiva congiunta.
    Description: Published
    Description: 124-127
    Description: 1.1. TTC - Monitoraggio sismico del territorio nazionale
    Description: N/A or not JCR
    Description: open
    Keywords: rete sismica ; ancona ; acquisizione dati ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous ; 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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  • 11
    Publication Date: 2017-04-04
    Description: Da alcuni anni l’INGV e la Regione Marche collaborano nell’azione di monitoraggio sismico del territorio regionale. Nella sede di Ancona del CNT sono acquisiti in tempo reale i segnali sismici di circa 80 stazioni dell’Italia centro-orientale. Si è reso pertanto necessario sviluppare applicativi utili al controllo degli apparati che compongono il sistema di monitoraggio. In particolare, vengono controllati: 1) lo stato di funzionamento delle trasmissioni radio ed ethernet; 2) lo stato dell’alimentazione delle stazioni e il numero di satelliti ricevuti dagli apparati GPS; 3) la quantità di segnale sismico archiviato e i gaps del segnale continuo; 4) i livelli di rumore di fondo e la qualità del segnale sismico.
    Description: Published
    Description: 104-107
    Description: 1.1. TTC - Monitoraggio sismico del territorio nazionale
    Description: N/A or not JCR
    Description: open
    Keywords: rete sismica ; ancona ; centro acquisizione ; telecomunicazioni ; qualità segnali ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous ; 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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  • 12
    Publication Date: 2017-04-04
    Description: A Pilot Project for CO2 injection and storage was proposed for a gas storage area located at Cortemaggiore (Piacenza), in northern Italy. This project is conducted both to verify the injection techniques and to analyze the potentiality of CO2 as a cushion gas. Starting from 2004, a series of analysis has been conducted to verify suitability and feasibility of this operation. The injection phase will be preceded by a passive seismic monitoring in order to measure the background seismicity of the area. Seismic monitoring will be carried out during the 3 years of the injection phase and will continue also for a control period of 2 years, following the working phase. The Milano - Pavia Department of the Istituto Nazionale di Geofisica e Vulcanologia is in charge of the surface seismic monitoring. To study the background seismicity a microseismic network composed by 7 seismic stations has been realized. On February 2010, a first test phase has been conducted for 3 sites. The network was completed with 4 more stations on May 2010. All stations are composed by a 24-bit digital recorder (Lennartz M24/NET) with GPS time signal. The study area is characterized by a very high anthropic and industrial noise. In order to improve the quality of the seismic signals, 4 stations have been installed in a 100 m deep borehole. The seismic sensors (Lennartz LE-3D/BH for the borehole and LE-3Dlite MKI for the installation at the surface) have similar technical characteristics with 1 Hz free period, cutoff frequency at 80 Hz and dynamic range of 136 dB. In this first stage we analyzed the microseismic noise level and evaluated the detection capability of the network. Using the RMS measurements the borehole stations indicate a reduction on the noise by a factor of 2.5. A more detailed analysis, performed using the density function distribution of the power spectra, evidences a 10 dB gain for the borehole stations in the frequency band 1 - 10 Hz. Noise measurements have been used also to determine the minimum magnitude for the events detection. Using a point source model to simulate seismic events, we verified the expected detection levels by comparing the estimates obtained with the simulation and the local events recorded by the seismic network.
    Description: Published
    Description: 12
    Description: 1.1. TTC - Monitoraggio sismico del territorio nazionale
    Description: N/A or not JCR
    Description: open
    Keywords: seismic monitoring ; gas storage ; micro-seismicity ; 04. Solid Earth::04.02. Exploration geophysics::04.02.99. General or miscellaneous ; 04. Solid Earth::04.02. Exploration geophysics::04.02.06. Seismic methods ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous ; 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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  • 13
    Publication Date: 2017-04-04
    Description: Nell’ambito del progetto FIRB-Airplane [“Piattaforma di ricerca multidisciplinare su terremoti e vulcani”, fondi MIUR 2007-2011 responsabili: Cocco, Amato e Stucchi1] dalla seconda metà del 2009 è stata installata una rete densa di stazioni sismiche nell’area dell’Alta Val Tiberina (AVT, Figura 1), i cui dati in continuo vengono trasmessi alla sede di Ancona del CNT attraverso una dorsale Wi-Fi HYPERLAN [Monachesi e Cattaneo, 2010]. La rete è stata progettata cercando di rispettare alcuni criteri, tra cui: controllo continuo della funzionalità delle singole stazioni, flessibilità nella scelta dei siti, riduzione del rischio di fulminazioni, possibilità di abbinare stazioni sismiche e stazioni geodetiche. A tal fine sono stati adottati strumenti a basso consumo per quel che riguarda acquisitori e sistemi di trasmissione, accompagnati dall’utilizzo di sistemi di alimentazione autonomi e sistemi di telecontrollo
    Description: Published
    Description: 91-93
    Description: 1.1. TTC - Monitoraggio sismico del territorio nazionale
    Description: N/A or not JCR
    Description: open
    Keywords: rete sismica ; alta val tiberina ; sistemi alimentazione ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous ; 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)
    Type: article
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  • 14
    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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  • 15
    Publication Date: 2017-04-04
    Description: Attualmente presso la sede di Ancona del CNT sono acquisiti i dati relativi a 58 stazioni in realtime ed a 13 stazioni dial-up. In particolare la sede di Ancona ha la funzione di server nei confronti della sala sismica nazionale per 28 stazioni in realtime e client per le rimanenti 30. Le stazioni dial-up hanno una connessione con radio modem (8) o con modem GSM (5). Gli acquisitori gestiti sono: GAIA1 e GAIA2, Trident/Cygnus, HDR24 e Lennartz Mars88/MC/RC. I sensori sono: Trillium 40-120-240s; Lennartz LE3D- 5s/1s/lite/BH, Mark L4-3D, Episensor ES-T. Il sistema di acquisizione dati è basato su Seiscomp31, mentre la detezione degli eventi avviene tramite Earthworm
    Description: Published
    Description: 19-21
    Description: 1.1. TTC - Monitoraggio sismico del territorio nazionale
    Description: N/A or not JCR
    Description: open
    Keywords: rete sismica ; monitoraggio ; marche ; alta val tiberina ; 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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  • 16
    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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  • 17
    Publication Date: 2017-04-04
    Description: L’utilizzo di sensori in pozzo ha l’obiettivo di migliorare il rapporto segnale-disturbo per poter registrare segnali di eventi sismici in zone dove le registrazioni in superficie sono corrotte dai disturbi. Infatti, le registrazioni superficiali sono affette dal noise sismico ambientale il quale è particolarmente elevato in zone industrializzate a frequenze generalmente superiori ad 1 Hz [McNamara and Buland, 2004]. La RSN dell’INGV, gestita dal CNT [vedi Delladio, 2011 - in questo volume], è dotata attualmente di 6 sensori in pozzo, ubicati nelle seguenti località: Castelleone (CR), Imola (BO), Bellaria (RN), Senigallia (AN), Sansepolcro (AR), Città di Castello (PG). Le prime 4 località si trovano in pianura padana (Castelleone e Imola) e sulla costa adriatica (Bellaria e Senigallia): in questi siti l’utilizzo di un sensore in pozzo ha lo scopo di ottenere registrazioni in cui i disturbi antropici possano essere significativamente abbattuti, in quanto le aree citate sono tra le più industrializzate e urbanizzate del territorio nazionale [Marzorati and Bindi, 2006]. I pozzi di Sansepolcro e Città di Castello rientrano nell’area di interesse della Faglia Alto Tiberina, in cui terremoti di piccolissima magnitudo vengono registrati solo in siti particolarmente silenziosi dal punto di vista del noise sismico ambientale; perciò i due sensori in pozzo hanno lo scopo di avere un punto di osservazione più vicino alla sorgente dei segnali che si vogliono registrare. Nei prossimi paragrafi sono mostrati alcuni esempi utili per poter valutare l’efficienza dei sensori in pozzo.
    Description: Published
    Description: 72-75
    Description: 1.1. TTC - Monitoraggio sismico del territorio nazionale
    Description: N/A or not JCR
    Description: open
    Keywords: sensori ; pozzo ; borehole ; noise sismico ; 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: In this paper the history of the Mobile Seismic Network of the Osservatorio Vesuviano (at present Department of Napoli of the Istituto Nazionale di Geofisica e Vulcanologia – INGV) is described. The instrumental development and the main research and monitoring activities since the early 1980’ are reported. Starting from the analog stations with magnetic tape recording to the first digital stations with trigger recording, until the modern multichannel 24bit devices, the technological development of the last 30 years has given a strong contribution to increase the knowledge in the seismology and seismotectonics fields. The Mobile Seismic Network has been engaged in active and passive seismic studies both on volcanic and tectonic areas. Particularly, the contribution of the Mobile Seismic Network for the monitoring of Neapolitan active volcanoes has been very important to improve the Permanent Network. During seismic crises high quality data have been gathered allowing detailed analyses of the seismic activity. Moreover, the time synchronization by means of GPS time code allowed the deployment of the Mobile Network abroad and the collaboration with the main international research institutes. At present, the Mobile Seismic Network of the Osservatorio Vesuviano is developing on multichannel acquisition systems, also in array configuration, to gathered simultaneously seismic signals with a large frequency band.
    Description: Published
    Description: 1-51
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: 3.2. Tettonica attiva
    Description: N/A or not JCR
    Description: open
    Keywords: mobile network ; Vesuvius ; Campi Flegrei ; data acquisition ; 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 ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 19
    Publication Date: 2017-04-04
    Description: Il Centro di Ricerche Sismologiche (CRS) dell’Istituto Nazionale di Oceanografia e di Geofisica Sperimentale - OGS è stato istituito con la legge n. 399 del 30 novembre 1989 col fine istituzionale di: “...svolgere, in autonomia scientifica e secondo specifici progetti: ricerche sulla sismicità e sulla sismogenesi dell’Italia nordorientale, gestendo e sviluppando inoltre la connessa rete di rilevamento sismico anche per fini di protezione civile. Nei campi di sua competenza il dipartimento svolge inoltre: attività applicativa; studi e ricerche sulle tecnologie di acquisizione, trasmissione e trattamento del segnale sismico; studi e ricerche per l’affinamento del modello sismotettonico dell’Italia nord-orientale.” Dal 2003, in seguito alla conferenza “Integrating the Seismic Monitoring in Central Europe” tenutasi a Udine e al Workshop “Beyond Frontiers: Seismic Networks in the Southern Alps” organizzato a Trieste, l’OGS ha partecipato al progetto europeo Interreg IIIa Italia/Austria “Reti sismologiche senza frontiere nelle Alpi sudorientali” 1. Il progetto nasce dalla stretta collaborazione esistente tra: • il CRS dell’OGS a Udine; • la Protezione Civile della Regione Friuli-Venezia Giulia (FVG); • l’allora Dipartimento di Scienze della Terra (DST) dell’Università di Trieste (adesso Dipartimento di Geoscienze); • lo Zentralanstalt für Meteorologie und Geodynamik, Hauptabteilung Geophysik di Vienna in Austria (ZAMG); • l’Urad za seizmologijo, geologijo, Agencija Republike Slovenije za okolje, di Lubiana in Slovenia (ARSO). Il terremoto di Bovec, avvenuto in prossimità dei confini tra FVG, Carinzia e Slovenia nel 1998, ha evidenziato l’importanza di un’integrazione e potenziamento delle reti delle diverse nazioni. In particolare, in tale occasione si è evidenziato: l’eterogeneità della strumentazione esistente nelle diverse reti, la mancanza di connessione dedicata tra i centri sismologici anche all’interno della stessa nazione e la mancanza di un sistema di elaborazione ed archiviazione dei dati omogeneo. Lo scopo del progetto è stato quindi l’integrazione transfrontaliera delle reti sismologiche presenti nelle tre nazioni per far fronte alle necessità di protezione civile e per scopi di ricerca scientifica. La disponibilità in tempo reale di forme d’onda dei terremoti permette, infatti, l’analisi immediata dei dati in maniera automatica che fornisce informazioni rapide ed affidabili alle autorità di protezione civile. Gli obiettivi principali raggiunti durante il progetto sono: 1. la creazione di un centro di raccolta dati in tempo reale presso la Sala Operativa Regionale (SOR) di Palmanova della Protezione Civile del Friuli-Venezia Giulia e l’adattamento dei centri raccolta dati del DST, dell’OGS e di Vienna a questi scopi. La duplicazione dei centri di raccolta dati e delle connessioni tra questi garantisce il funzionamento del sistema anche nel caso che uno o più centri siano fuori uso per i danni subiti da un sisma distruttivo; 2. l’individuazione e la realizzazione di uno o più sistemi di connessione dati efficienti e sicuri tra le stazioni ed i centri di raccolta; 3. la ridefinizione della geometria attuale delle reti, in funzione della migliore copertura possibile delle aree potenzialmente pericolose a ridosso dei confini di stato; 4. la programmazione dei protocolli comuni d’intervento in caso di forti terremoti.
    Description: Published
    Description: 38-41
    Description: 1.1. TTC - Monitoraggio sismico del territorio nazionale
    Description: N/A or not JCR
    Description: open
    Keywords: seismic monitoring ; OGS ; Northeast Italy ; real time ; 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: 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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  • 21
    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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  • 22
    Publication Date: 2017-04-04
    Description: The aim of this study is the sharing of waveforms recorded by several Istituto Nazionale di Geofisica e Vulcanologia (INGV) temporary stations (managed by the Milan-Pavia section; INGV MI-PV). These stations were installed after the April 6, 2009, Mw 6.3, L'Aquila earthquake (central Italy). The work synthesizes the activities conducted in the field by the INGV MI-PV working group over the three months following the mainshock. The field activities were developed in four different phases that were defined according to their time periods. Starting from April 7, 2009, for the first phase, the temporary stations were installed in correspondence with the more damaged areas. The scope was to record the strongest aftershocks in the days that followed the mainshock. In this phase, the stations were composed of a sixcomponent acquisition system that was coupled with both a weak-motion and a strong-motion sensor. After the first month, the last three phases of installation investigated the seismic responses of sites located in the epicentral area, involving villages within a radius of about 20 km from the epicenter of the April 6 mainshock. In this way, over four specific time-period phases, the stations were installed in sites with different lithological and geomorphological conditions. The instruments worked from April 7 to July 14, 2009; in this period, 9,155 aftershocks (134,262 accelerometric waveforms and 133,242 velocimetric waveforms), with ML ≤5.3 were recorded. This study describes the dataset of these earthquake waveforms recorded with both velocity and acceleration transducers. Selected waveforms are available through ftp://ftp.mi.ingv.it/download/RAIS-TS_rel01/, with their corresponding information concerning instrumental characteristics, installation sites, and earthquakes recorded.
    Description: Published
    Description: 101-113
    Description: 1.1. TTC - Monitoraggio sismico del territorio nazionale
    Description: JCR Journal
    Description: open
    Keywords: Seismological data ; L'Aquila earthquake ; Aftershocks ; 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: 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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  • 24
    Publication Date: 2017-04-04
    Description: A seismic noise recording experiment has been carried out in the Campi Flegrei volcanic area from March 9 to 26, 2009 in the framework of the INGV-DPC 2007-2009 agreement (Project V1 – UNREST). The project aimed at the realization of an integrated method for the definition of the unrest phases at Campi Flegrei. 21 digital three-component seismic stations equipped with broad band seismometers have been added to the existing 11 digital stations already deployed in the area. The preliminary results show a correlation between the seismic noise level and the anthropic activity, whereas the meteorological conditions seem affecting the low frequency seismic noise. These results are important to define the detection thresholds of the seismic signals generated during a possible renewal phase of the volcanic activity.
    Description: Published
    Description: 1-21
    Description: N/A or not JCR
    Description: open
    Keywords: Campi Flegrei ; seismic noise ; spectral analysis ; wave polarization ; 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::04.06.08. Volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis ; 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)
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  • 25
    Publication Date: 2017-04-04
    Description: The effect of pressure on melt viscosity was investigated for five compositions along the join An(CaAl2Si2O8)–Di(CaMgSi2O6) and four alkali silicates containing lithium, sodium, and potassium in constant ratio of ∼ 1:1:1, but alkali-silica ratios are varying. The experiments were performed in an internally heated gas pressure vessel at pressures from 50 to 400 MPa in the viscosity range from 108 to 1011.5 Pa⋅s using parallel plate viscometry. The polymerized An composition shows a negative pressure dependence of viscosity while the other, more depolymerized compositions of the join An–Di have neutral to positive pressure coefficients. The alkali silicates display neutral to slightly positive pressure coefficients for melt viscosity. These findings in the high viscosity range of 108–1011 Pa⋅s, where pressure appears to be more efficient than in low viscous melts at high temperature, are consistent with previous results on the viscosity of polymerized to depolymerized melts in the system NaAlSi3O8–CaMgSi2O6 by Behrens and Schulze [ H. Behrens and F. Schulze, Am. Mineral. 88, 1351 (2003) ]. Thus we confirm that the sign of the pressure coefficient for viscosity is mainly related to the degree of melt polymerization in silicate and aluminosilicate melts.
    Description: DFG Grant n.°BE1720/9
    Description: Published
    Description: 044504-14
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: JCR Journal
    Description: open
    Keywords: viscosity ; polymerisation ; anorthite ; diopside ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 26
    Publication Date: 2017-04-04
    Description: Questa nota presenta una sintesi delle attività svolte durante il rilievomacrosismico del terremoto avvenuto tra le province di Parma e Reggio Emilia il 23 dicembre 2008. La scossa di Ml 5.2 è stata localizzata a sud di Parma ed è stata avvertita in tutta l’Italia settentrionale e in gran parte della Liguria e della Toscana. Il presente rapporto illustra lemodalità di intervento del teamQUEST, relative al rilievo degli effetti e alla valutazione in intensità MCS in particolare per le località della zona epicentrale. L’ampia documentazione fotografica illustra alcuni dettagli delle tipologie di danneggiamento rilevate e consente di comprendere meglio le valutazioni dell’intensità macrosismica. This paper presents an overview of the activities performed during the macroseismic field survey of the earthquake that occurred in the Parma and Reggio Emilia region on December 23, 2008. The mainshock (Ml=5.2), was located south of the city of Parma and was resolutely felt through Northern Italy. The report here presented shows the procedures carried out by QUEST (Quick Earthquake Survey Team), concerning the survey. QUEST has been engaged in gathering the damage information and in assessing the macroseismic intensity, in particular about the epicentral area. A copious photo collection shows details of the observed damage nature and allows to better illustrate the intensity
    Description: Published
    Description: 1-41
    Description: 5.1. TTC - Banche dati e metodi macrosismici
    Description: N/A or not JCR
    Description: open
    Keywords: rilievo macrosismico ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous ; 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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  • 27
    Publication Date: 2019-11-04
    Description: Seismic monitoring in Italy has strongly improved since the 1997 Umbria-Marche earthquake sequence. This has made the National Seismic Network (RSN) a powerful tool both to rapidly locate and quantify thousands of earthquakes occurring in Italy every year, and to study the seismic activity in detail, accumulating an impressive high quality data set that will be exploited in the coming years to understand earthquake processes and to investigate the deep structure. This paper summarizes and compares the basic features of the seismicity recorded in 2000 and 2006, before and after the implementation of the new RSN, showing that the number of well located earthquakes has more than doubled and that the completeness magnitude has dropped from ~2.3 to ~1.7. In addition, we concentrate on the evaluation of the current automatic location and magnitudes versus the revised ones, published routinely in the INGV bulletins. We show that the rapid estimates of locations and magnitudes are robust and reliable for most regions in Italy: more than 75% of the earthquakes are located in real time within 10km from the «true» locations, whereas the rapid magnitudes ML are within ±0.4 from the revised values in 90% of cases. The comparison between real-time and revised locations shows that there are a few regions in Italy where a further network improvement is still desirable. These include all the off-shore regions, Calabria, western Sicily, the Alpine and Po Plain region, and some small areas along the peninsula.
    Description: Published
    Description: 417-431
    Description: 5.2. TTC - Banche dati di sismologia strumentale
    Description: JCR Journal
    Description: open
    Keywords: seismic networks ; seismicity ; real-time seismology ; Italy ; Italian Seismic Bulletin ; 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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  • 28
    Publication Date: 2021-03-01
    Description: Questo lavoro presenta una utility per il GIS MapInfo™ sviluppata per l'archiviazione ed elaborazione dei dati macrosismici dalla fase di georeferenziazione fino al plottaggio finale su mappa. L'identificazione della località associata con un'osservazione macrosismica è un'operazione che talvolta può causare errori ed in seguito problemi nell'analisi ed interpretazione dei dati. La routine MacroMap fornisce uno strumento che in modo semplice e veloce aiuti nell'identificazione della corretta località a cui attribuire l'informazione macrosismica durante lo studio di un terremoto. L'utility è strutturata per utilizzare il formato della directory geografica DIR04 e le procedure adottate nella compilazione del DataBase Macrosismico Italiano DBMI04. MacroMap è stata sperimentata "sul campo" durante alcune indagini macrosismiche e tiene conto dell'esperienza e dei suggerimenti degli operatori del Gruppo QUEST (QUick Earthquake Survey Team). I campi di utilizzo di MacroMap vanno dalla realizzazione speditiva di mappe e tabelle per la produzione di report macrosismici per la Protezione Civile, alla revisione di terremoti storici, grazie all'avanzato sistema di query disponibile per la selezione dei toponimi del database geografico.
    Description: Published
    Description: 1-21
    Description: 5.1. TTC - Banche dati e metodi macrosismici
    Description: N/A or not JCR
    Description: open
    Keywords: Osservazioni macrosismiche ; 04. Solid Earth::04.06. Seismology::04.06.05. Historical seismology ; 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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  • 29
    Publication Date: 2017-04-04
    Description: The modern digital seismic stations are provided with 24 bit A/D converters, high capacity recording systems and broad-band seismometers. Nevertheless, few tens year old seismic stations can be still able to give an useful contribution to seismic monitoring. Some out-of-date seismic stations, such as the Lennartz PCM 5800, are characterized by the data acquisition in trigger mode on magnetic tape, allowing a continuous recording time of about 90 minutes. We have checked the possibility to substitute the Uher tape recorder of the Lennartz PCM 5800 stations with modern digital recorder, in order to give a new life to these stations. Several type of digital recorders have been tried. According to the results of our trials, the Hi-MiniDisc (Hi-MD) recorder is resulted the most useful one. This apparatus records on 1GB magneto-optical disks with a continuous recording time up to about 8 hours. This time allows to record about 500 trigger windows of about 50-60 seconds on one disk, about 5 time the old magnetic tape. According with these results, the Lennartz PCM 5800 digital seismic stations can be useful during seismic experiments or as a support of the Permanent Seismic Networks at local and regional scale.
    Description: Published
    Description: 1-17
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: N/A or not JCR
    Description: open
    Keywords: seismic station ; temporary network ; 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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  • 30
    Publication Date: 2017-04-04
    Description: Seismic networks are worldwide diffuse to monitor both volcanic and tectonic seismogenetic areas. Some differences, such the basement on which the seismometer is located and the environmental conditions, characterize the installation of seismic stations in volcanic and tectonic areas. Nevertheless, some basic principles are common. To obtain good quality seismic data is very important to realize a high grade installation of all the instruments equipping a seismic station. Several procedure must be taken into account to optimize the instrument setting up. Electronic noise may be minimize using proper connecting line and adequate grounding. Effective lightning protections are essential to save instruments from both surges and strikes. Good seismometer ground coupling improves the signal quality and the signal-to-noise ratio. These procedures have been carried out at the Osservatorio Vesuviano to improve the existing seismic network as well as the installation of the new stations. As a result of this action an improvement of both the signal-to-noise ratio and the network reliability has been obtained.
    Description: Published
    Description: 1-20
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: open
    Keywords: seismic network ; siting ; 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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  • 31
    Publication Date: 2021-06-15
    Description: Field studies indicate that nearly all eruptions in volcanic edifices and rift zones are supplied with magma through fractures (dykes) that are opened by magmatic overpressure. While (inferred) dyke injections are frequent during unrest periods, volcanic eruptions are, in comparison, infrequent, suggesting that most dykes become arrested at certain depths in the crust, in agreement with field studies. The frequency of dyke arrest can be partly explained by the numerical models presented here which indicate that volcanic edifices and rift zones consisting of rocks of contrasting mechanical properties, such as soft pyroclastic layers and stiff lava flows, commonly develop local stress fields that encourage dyke arrest. During unrest, surface deformation studies are routinely used to infer the geometries of arrested dykes, and some models (using homogeneous, isotropic half-spaces) infer large grabens to be induced by such dykes. Our results, however, show that the dyke-tip tensile stresses are normally much greater than the induced surface stresses, making it difficult to explain how a dyke can induce surface stresses in excess of the tensile (or shear) strength while the same strength is not exceeded at the (arrested) dyke tip. Also, arrested dyke tips in eroded or active rift zones are normally not associated with dyke-induced grabens or normal faults, and some dykes arrested within a few metres of the surface do not generate faults or grabens. The numerical models show that abrupt changes in Young's moduli(stiffnesses), layers with relatively high dyke-normal compressive stresses (stress barriers), and weak horizontal contacts may make the dyke-induced surface tensile stresses too small for significant fault or graben formation to occur in rift zones or volcanic edifices. Also, these small surface stresses may have no simple relation to the dyke geometry or the depth to its tip. Thus, for a layered crust with weak contacts, straightforward inversion of surface geodetic data may lead to unreliable geometries of arrested dykes in active rift zones and volcanic edifices.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: dyke injection ; dyke arrest ; crustalstresses ; crustal layering ; surface deformation ; volcanic hazard ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks
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  • 32
    Publication Date: 2019-11-04
    Description: The broad-band teleseismics records of the earthquake of October 29,1989 in Algeria (MW = 6.0) allow a detailed study of the rupture process of this earthquake. The focal mechanism obtained by P and SH modeling corresponds to reverse faulting with a small amount of left-lateral movement along a fault striking 246° and dipping 56°. The rupture is found to be complex with two sub-events separated in time but occurring on the same plane. The lowfrequency records of an accelerometer located some 25 km to the west of the main shock are also better fi tted when the rupture is composed of a double pulse. In the two cases, there is strong evidence for the rupture to propagate from south-west towards north-east.The relocalisation of the main shock by using a master-event technique and the data from Italian and Spanish stations led to the same conclusions. Soon after the main event, a temporary seimic network was installed in the epicentral area. The aftershock clouds defi ne a SW-NE fault dipping to the NW compatible with the results of the modelisations of the teleseismic body-waves and the accelerogram. The focal mechanisms correspond mainly to reverse faulting. The maximum principal direction of the stress tensor obtained from the inversion is about N-S and the minimum is vertical, typical of a compressive regime. The Chenoua earthquake took place on a fault which was not recognized as active. Repeated comparable seismic events on this fault and on the fault that borders the massif to the south explain this intriguing topographic feature.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: North Africa ; seismicity ; earthquake ; 04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
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  • 33
    Publication Date: 2019-11-04
    Description: The El Camp Fault (Catalan Coastal Ranges, NE Iberian Peninsula) is a slow slipping normal fault whose seismic potential has only recently been recognised. New geomorphic and trench investigations were carried out during a training course across the El Camp Fault at the La Porquerola alluvial fan site. A new trench (trench 8) was dug close to a trench made previously at this site (trench 4). With the aid of two long topographic profiles across the fault scarp we obtained a vertical slip rate ranging between 0.05 and 0.08 mm/yr. At the trench site, two main faults, which can be correlated between trenches 8 and 4, make up the fault zone. Using trench analysis three paleoseismic events were identified, two between 34.000 and 125.000 years BP (events 3 and 2) and another event younger than 13 500 years BP (event 1), which can be correlated, respectively, with events X (50.000- 125.000 years BP), Y (35.000-50.000 years BP) and Z (3000-25.000 years BP). The last seismic event at the La Porquerola alluvial fan site is described for the first time, but with some uncertainties.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: paleoseismicity ; trenching ; normal fault ; Catalan Coastal Ranges ; El Camp Fault ; 04. Solid Earth::04.04. Geology::04.04.01. Earthquake geology and paleoseismology ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
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  • 34
    Publication Date: 2019-11-04
    Description: Recent seismological studies contribute to better understand the first order characteristics of earthquake occurrence in Italy, identifying the potential sites for moderate to large size earthquakes. Ad hoc passive seismic experiments performed in these areas provide information to focus on the location and geometry of the active faults more closely. This information is relevant for assessing seismic hazard and for accurately constraining possible ground shaking scenarios. The area around the Città di Castello Basin, in the Northern Apennines (Central Italy), is characterized by the absence of instrumental seismicity (M 〉 2.5), it is adjacent to faults ruptured by recent and historical earthquakes. To better understand the tectonics of the area, we installed a dense network of seismic stations equipped with broadband and short period seismometers collecting data continuously for 8 months (October 2000-May 2001). The processing of ~ 900 Gbyte of data revealed a consistent background seismicity consisting of very low magnitude earthquakes (ML 〈 3.2). Preliminary locations of about 2200 local earthquakes show that the area can be divided into two regions with different seismic behaviour: an area to the NW, in between Sansepolcro and Città di Castello, where seismicity is not present. An area toward the SE, in between Città di Castello, Umbertide and Gubbio, where we detected a high microseismicity activity. These findings suggest a probable different mechanical behaviour of the two regions. In the latter area, the seismicity is confined between 0 and 8 km of depth revealing a rather well defined east-dipping, low angle fault 35 km wide that cuts through the entire upper crust down to 12-15 km depth. Beside an apparent structural complexity, fault plane solutions of background seismicity reveal a homogeneous pattern of deformation with a clear NE-SW extension.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: microseismicity ; low-angle normalfault ; seismic gap ; seismic hazard ; 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
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  • 35
    Publication Date: 2019-11-04
    Description: The formation of the two particular lava domes in Hokkaido, Japan is described and interpreted mainly from geophysical viewpoints. The 1909 eruption of Tarumai volcano was not violent but produced a lava dome over four days. The growth rate of the dome is discussed under the assumption that the lava flow was viscous and plastic fluid during its effusion. By Hagen-Poiseuilles Law, the length of the conduit of the lava dome is rather ambiguously determined as a function of viscosity of the magma and diameter of the conduit. The 1944 Usu dome extruded as a parasitic cone of Usu volcano, not in the crater, but in a flat cornfield at the foot of the volcano. From the beginning to the end for more than 17 months, seismometric and geodetic observations of the dome activity were carried out by several pioneering geophysicists. Utilizing their data, pseudo growth curves of the dome at each stage can be drawn. The lava ascended rather uniformly, causing uplift of the ground surface until half-solidified lava reached the surface six months after the deformation began. Thereafter, the lava dome added lateral displacements and finally achieved its onion structure. These two lava domes are of contrasting character, one is andesitic and formed quickly while the other is dacitic and formed slowly, but both of them behaved as viscous and plastic flows during effusion. It is concluded that both the lava domes formed by uplift of magma forced to flow through the conduits, analogous to squeezing toothpaste out of a tube.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: lava domes ; Tarumai volcano ; Usu volcano ; squeeze of magma ; growth rate of domes ; Hagen-Poiseuille's Law ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous
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  • 36
    Publication Date: 2019-11-04
    Description: A site response experiment was performed in the basin of Città di Castello (a small town in Central Italy) in May 2001. This study is part of a project on the evaluation of seismic hazard in seismogenic areas funded by the Gruppo Nazionale Difesa dai Terremoti (GNDT). The experiment consisted of a dense fixed transect configuration with most of the stations recording in continuous mode, and several ambient noise measurements both in single station and in array configuration spread over the investigated area. The dense transect was composed of 26 seismic stations in a crosswise configuration with a maximum inter-station distance of 250 m. The stations were deployed in the southern part of the basin, from the eastern bedrock outcrop to the western edge, across the town. About 70 earthquakes were recorded during 10 days of deployment, generally low magnitude or regional events. We located 23 earthquakes and 17 of them were located using the waveform similarity approach at 4 stations outside the target area. These 4 stations were part of a dense temporary seismic network involved in a previous experiment of the same project, aimed at performing a high-resolution picture of the local seismicity. Delay analysis on the recorded waveforms allowed us to infer the basin geometry at depth and estimate the S-wave velocity of sediments. Moreover, we evaluated relative site response along the E-W transect by performing a standard spectral ratio. Amplification factors up to 9 are found inside the basin; at frequencies above 5 Hz stations closer to the edges show higher amplification, whereas stations located in the middle of the basin, where the alluvial sediments are thicker (CD11-CD14), show higher amplification below 5 Hz. We considered the average amplification in two frequency bands (1-5 Hz and 5-10 Hz), representative of the resonance frequency for 2-3 storey buildings and 1 storey houses,respectively. Our results suggest that the potential hazard for 2-3 storey buildings is higher in the center of the basin (amplification factor up to 6), and for 1 storey houses is higher at the edges (amplification factor up to 5).
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: dense seismic array ; weak motion ; ambient noise ; basin geometry ; urban area ; 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
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  • 37
    Publication Date: 2019-11-04
    Description: To verify the results of seismic microzoning and to improve techniques, the damage data of past destructive earthquakes is an important key reference. The damage data of the 1923 Kanto, Japan, earthquake in the epicentral region are collected and compiled to produce the most reliable and detailed damage map. The damage map is compared with the results from the existing damage assessment and is used to discuss revision of the site amplification evaluation.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: seismic microzoning ; damage data ; 04. Solid Earth::04.06. Seismology::04.06.04. Ground motion ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
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  • 38
    Publication Date: 2019-11-04
    Description: Volcanic eruptions are unsteady multiphase phenomena, which encompass many inter-related processes across the whole range of scales from molecular and microscopic to macroscopic, synoptic and global. We provide an overview of recent advances in numerical modelling of volcanic effects, from conduit and eruption column processes to those on the Earth s climate. Conduit flow models examine ascent dynamics and multiphase processes like fragmentation, chemical reactions and mass transfer below the Earth surface. Other models simulate atmospheric dispersal of the erupted gas-particle mixture, focusing on rapid processes occurring in the jet, the lower convective regions, and pyroclastic density currents. The ascending eruption column and intrusive gravity current generated by it, as well as sedimentation and ash dispersal from those flows in the immediate environment of the volcano are examined with modular and generic models. These apply simplifications to the equations describing the system depending on the specific focus of scrutiny. The atmospheric dispersion of volcanic clouds is simulated by ash tracking models. These are inadequate for the first hours of spreading in many cases but focus on long-range prediction of ash location to prevent hazardous aircraft - ash encounters. The climate impact is investigated with global models. All processes and effects of explosive eruptions cannot be simulated by a single model, due to the complexity and hugely contrasting spatial and temporal scales involved. There is now the opportunity to establish a closer integration between different models and to develop the first comprehensive description of explosive eruptions and of their effects on the ground, in the atmosphere, and on the global climate.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: numerical modeling ; explosive volcanic eruptions ; conduit flow ; multiphase flow simulation ; stratospheric sulfate aerosol ; 01. Atmosphere::01.01. Atmosphere::01.01.07. Volcanic effects ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases
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  • 39
    Publication Date: 2019-11-04
    Description: This study presents results of ambient noise measurements from temporary single station and small-scale array deployments in the northeast of Basle. H/V spectral ratios were determined along various profiles crossing the eastern masterfault of the Rhine Rift Valley and the adjacent sedimentary rift fills. The fundamental H/V peak frequencies are decreasing along the profile towards the eastern direction being consistent with the dip of the tertiary sediments within the rift. Using existing empirical relationships between H/V frequency peaks and the depth of the dominant seismic contrast, derived on basis of the ?/4-resonance hypothesis and a power law depth dependence of the S-wave velocity, we obtain thicknesses of the rift fill from about 155 m in the west to 280 m in the east. This is in agreement with previous studies. The array analysis of the ambient noise wavefield yielded a stable dispersion relation consistent with Rayleigh wave propagation velocities. We conclude that a significant amount of surface waves is contained in the observed wavefield. The computed ellipticity for fundamental mode Rayleigh waves for the velocity depth models used for the estimation of the sediment thicknesses is in agreement with the observed H/V spectra over a large frequency band.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: H/V ratio ; ambient vibration ; array analysis ; fundamental frequency ; Rhine Rift Valley ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
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  • 40
    Publication Date: 2019-11-04
    Description: Popocatepetl volcano is a high-risk active volcano in Central Mexico where the highest population density in the country is settled. Radon in the soil and groundwater together with water chemistry from samples of nearby springs were analysed as a function of the 2002-2003 volcanic activity. The measurements of soil radon indicated fluctuations related to both the meteorological and sporadic explosive events. Groundwater radon showed essential differences in concentration due to the specific characteristics of the studied springs. Water chemistry showed also stability along the monitoring period. No anthropogenic pollution from Volatile Organic Compounds (VOCs) was observed. An overview of the soil radon behaviour as a function of the volcanic activity in the period 1994-2002 is also discussed.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: soil radon ; water chemistry ; volcanic activity ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous
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  • 41
    Publication Date: 2019-11-04
    Description: The seismic period which occurred in a portion of Guidonia Montecelio and Tivoli territory, two towns situated about twenty kilometres NE of Rome, affected four areas with a high density of population: Guidonia, Collefiorito, Villalba and Bagni di Tivoli. Even though the events had a very low magnitude (less than 3.0), local phenomena, like rumbles and strong vibrations of the ground, frightened inhabitants also because some months before (January 26, 2001) in a village named Marcellina situated a few kilometres away from Guidonia, a large sinkhole (600 m) had appeared without fore signals. The «Istituto Nazionale di Geofisica e Vulcanologia» (INGV) installed some digital stations that monitored the seismic phenomena. This paper has the aim to process all the information acquired during the period, both from the micro and macro seismic point of view, in order to explain the phenomenology that involved the area. The synergy of the two methodologies lead us to the conclusion that two different seismotectonic structures originated the events, one in an anti-apenninic direction, the other in a N-S direction.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: seismicity ; neotectonic ; 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::04.07. Tectonophysics::04.07.07. Tectonics
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  • 42
    Publication Date: 2019-11-04
    Description: In order to evaluate the detection and localisation improvement of a small aperture array in the Northern Apennines, we installed an irregularly spaced test configuration in the vicinity of Città di Castello (CDC) for a period of two weeks. The experimental array consisted of nine 3-component stations with inter-station distances between 150 m and 2200 m. Seismic data were digitised at 125 Hz and telemetered to a mobile acquisition, processing and storage centre. The data could only be recorded in trigger mode. The peculiarity of the test array installation was the exclusive use of 3-component sensors at all array sites, which also allowed beamforming for S-phases on the horizontal components. Since the altitudes of the single array sites differed considerably among each other, for f-k analysis and beamforming an elevation correction was included. During the two weeks of operation about 20 local earthquakes with magnitudes ML〈2.6, 1 regional, and several teleseismic events were recorded. In addition to these events, the array occasionally triggered on coherent noise-signals generated by local industrial activity. The data analysis was performed by means of f-k analysis and beamforming, providing wavenumber characteristics of the incident plane wave. Typical apparent velocities were determined to be 4.8 km/s and 6 km/s for Pg-phases and ~10 km/s for Pn-phases. We observed local seismic events, which occurred just beneath the array. In these cases wavefronts with unusual high apparent velocities, similar to those found for the Pn-phase, were observed. Since no continuously recorded array data were available, we extrapolated the lower detection magnitude threshold as a result of the SNR improvement due to array beamforming. Compared to the actual detection threshold of MT ~1.6 reached by the national seismic network in this area, a nine element array would improve this value up to MT ~ 0.8.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: seismic array ; beamforming ; f-kanalysis ; Central Apennines ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
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  • 43
    Publication Date: 2021-09-17
    Description: Several satellite techniques have been proposed to monitor events related to seismic and volcanic activity. A selfadaptive approach (RAT, Robust AVHRR Techniques) has recently been proposed which seems able to recognise space-time anomalies, differently related to such events, also in the presence of highly variable contributions from atmospheric (transmittance), surface (emissivity and morphology) and observational (time/season, but also solar and satellite zenithal angles) conditions. On the basis of NOAA-AVHRR data, the RAT aprroach has already been applied to Mount Etna volcanic ash cloud monitoring in daytime, and to seismic area monitoring in Southern Italy. This paper presents the theoretical basis for the extension of RAT approach also to nighttime volcanic ash cloud detection, together with its possible implementation to lava flow monitoring. One example of successful forecasting (few days before) of a new lava vent opening during the Mount Etna eruption of July 2001 will be discussed in some detail. Progress on the use of the same approach on seismically active area monitoring will be discussed by comparison with previous results achieved on the Irpinia-Basilicata earthquake (MS = 6.9), which occurred on November 23rd 1980 in Southern Italy.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: lava flows ; volcanic ash clouds ; Irpinia-Basilicata earthquake ; Robust AVHRR Techniques ; TIR anomaly ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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