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  • 1
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    Unknown
    Seismological monitoring of Campi Flegrei caldera (2008)
    Details
    Publication Date: 2017-04-04
    Description: Campi Flegrei is an active volcanic area posing a serious threat over Naples. Half of the city lies inside the caldera rim. The volcano has shown in the last 30 years different episodes of unrest, the most recent is still ongoing. For this reason the monitoring of this volcano is a fundamental task. The current seismic network consists of 8 short period and 5 broadband stations. The seismic monitoring is complemented by 2 infrasonic sensors and 3 dilatometers. The recent seismicity has been characterized by swarms of volcano-tectonic and long-period events. The network geometry allows an accurate location of VT events with a detection threshold of magnitudes less than 1.0 Some VT events have been recorder also by the infrasonic sensors showing interesting similarities. LP events have been recorded by both short period and broadband stations. The polarization analysis performed over the broadband recordings is an important tool for the real time detection of such events, related to the dynamics of the hydrothermal system. The ongoing developments consists in a progressive increasing of the number of broadband digital stations and infrasonic sensors, in improving the accuracy of hypocenter locations by using a 3D velocity model and in the implementation of new automatic techniques aimed at the detection, classification and analysis of seismic events.
    Description: Published
    Description: Vienna, Austria
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: open
    Keywords: Seismological monitoring ; caldera ; Campi Flegrei ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Oral presentation
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  • 2
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    Automatic real-time detection and location of Very Long Period events at Stromboli (2012)
    Details
    Publication Date: 2017-04-04
    Description: Signals with Very Long Periods (VLP) (1-60s) have been recorded on many active volcanoes. They are related with various dynamical processes in the volcano feeding system. Stromboli was one of the first volcanoes where such signals have been observed and analyzed. After the beginning of an anomalous eruptive activity in December 2002, a permanent broadband seismic network was deployed, by INGV-Osservatorio Vesuviano, in January 2003. Currently the network consists in 11 stations. Seismic data are continuously acquired by the INGV-Osservatorio Vesuviano in Naples, where they are analyzed in real time and stored. Preliminary results are immediately published on public web pages. In this paper we focus on the method used for detecting and locating VLP events. Such events have not a clear onset, so classical methods for automatic picking and location fails. Compared to common earthquakes signals, VLPs shows a high waveform coherence among different stations and a clear radial polarization toward the hypocenter. Using these features, hypocenters may be found searching for the points in the space having the highest coherence in the radial component. This is quantified using a modified semblance function over band-pass filtered (2-20 s) signals. The point having the highest semblance function value is the hypocenter. The semblance function is computed continuously for 10 s time windows over a regular grid centered on Stromboli, having a volume of 8000x8000x2000 m and a spacing of 100x100x50 m. VLP events are detected when the maximum value of the semblance function exceed a given threshold value. This task require heavy computation efforts. For this reason we use a 64 processor parallel computer for performing real-time analysis.
    Description: Published
    Description: Nice 25-30 April, 2004
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: open
    Keywords: AUTOMATIC ; REAL-TIME DETECTION ; LOCATION ; VERY LONG PERIOD ; STROMBOLI ; parallel computer ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 05. General::05.01. Computational geophysics::05.01.01. Data processing
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Conference paper
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  • 3
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    Seismological Insight on the Shallow Magma System (2012)
    AGU
    Details
    Publication Date: 2017-04-04
    Description: We present an overview of the volcanic seismicity recorded at Stromboli from January to September 2003. The data set starts few weeks after the onset of the eruption and covers most of the effusive phase and the subsequent recovery of the explosive activity. The most important variations occurred between May and July coinciding with the waning of the lava flow and the reappearance of Strombolian activity at the summit craters. All the parameters indicate that the shallow magmatic system has not undergone permanent changes during this period. The only significant variation related to the shallow conduit is the increase in volcanic tremor amplitude and the change in the spectral content of long-period events during the transition between effusive and explosive activity. A slight increase in the very-long-period (VLP) events source elevation seems to mark the rise of the magma at the end of the effusive phase. The variations in the VLP events occurrence rate are more likely to be attributed to changes in the gas flow rate and the bubble coalescence mechanism, therefore, to a deeper portion of the magmatic system. The 5 April paroxysm is associated only with a small increase of the activity in the following days.
    Description: Published
    Description: 279-286
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: reserved
    Keywords: Stromboli ; Seismological monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 4
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    The Stromboli Volcano Broadband Seismic Monitoring System (2012)
    Details
    Publication Date: 2017-04-04
    Description: After the beginning of the eruptive crisis that has interested the Stromboli volcano (Southern Italy) at the end of 2002, starting the second half of January 2003 it has been installed on the island a centralized broadband seismic network, at present composed by 11 stations, all equipped with Guralp CMG-40T (0,02-60 s period). The network is one of the first designed to monitor and analyze in real time the very long periods (VLP) events, which are produced, in the case of the Stromboli volcano, at a rate of hundreds per day. The disposition of the stations has been chosen in order to realize an azimuth and distance homogeneously distribution regarding possible seismic sources situated along the upper part of feeding system of the volcano. The network shows a distribution of stations that encircle the volcanic structure to various levels regarding the area of craters and the eruptive vents, with distance of the stations from the emission centers that vary between some hundreds of meters to about 2 kilometers. The signals, acquired using 24 bits A/D data loggers designed by INGV - CNT, are transmitted via UHF radiomodems to two intermediate centralization sites . The first one is the Observatory of S. Vincenzo where are centralized the stations installed on the northern side of the island, the second is the Observatory INGV in the Lipari island, where are centralized all the other stations. From these two intermediate centralization sites the data are transmitted via TCP/IP protocol, using the Italian scientific-academic internet network GARR, towards the INGV monitoring centers of Catania and Observatory Vesuviano (Naples), where the broadband signals are monitored and processed, using a 64 CPU computer cluster to perform the VLP real-time analysis.
    Description: Published
    Description: Vienna
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.6. Fisica del vulcanismo
    Description: open
    Keywords: eruptive crisis ; centralized broadband seismic network ; monitor and analyze in real time the very long periods ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 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)
    Type: Conference paper
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