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  • 1
    Publikationsdatum: 2020-12-15
    Beschreibung: The eruptive events of the July–August 2001 and October 2002–January 2003 at Mt. Etna provide new insights for reconstructing the complex geometry of the feeding system and their relationship to regional tectonics. The 2001 eruption took place mainly on the upper southern sector of the volcano. The eruption was preceded by a large earthquake swarm for a few days before its onset and accompanied by ground deformation and fracturing. The development of surface cracking along with the seismic pattern has allowed us to recognize three distinct eruptive systems (the SW–NE, NNW–SSE and N–S systems) which have been simultaneously active. Such eruptive systems are only the upper portions of a complex feeding system that was fed at the same time by two distinct magmas. The SW–NE and NNW–SSE systems, connected with the SE crater conduit, were fed by magma coming from depth, whereas the N–S system served instead as an ascending pathway for an amphibole-bearing magma residing in a shallow reservoir. The eruptive activity started again on October 2002 on the NE Rift Zone, where about 20 eruptive vents were aligned between 2500 and 1900 m a.s.l., and on the southern flank, from the central crater to the Montagnola. The onset of eruptive activity was accompanied by a seismic swarm. As in the 2001 eruptive event, two independent feeding systems formed, characterized by distinct magmas. The SW–NE system controlled the feeding of the Northeast Rift and was accommodated by left-lateral displacement along the WNW–ESE trending Pernicana Fault. The N–S system fed the eruptions on the southern flank. Moreover, the associated crustal deformation triggered seismic reactivation of tectonic structures in the eastern flank of the volcano and offshore. These two last eruptions indicate that at Mt. Etna the ascent of magma, as well as the accommodation of deformation, is strongly dominated by local extensional structures that are connected to a regional tectonic regime.
    Beschreibung: Published
    Beschreibung: 211-233
    Beschreibung: partially_open
    Schlagwort(e): extensional tectonics ; volcanic activity ; seismicity ; Sicily ; Mt. Etna ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 2
    Publikationsdatum: 2017-04-04
    Beschreibung: Seismic activity linked to the 2002–03 Mt. Etna eruption was investigated by analyzing the Md 〉 2.3 earthquakes. The results of 3D relocation were used to compute fault plane solutions and a selected dataset was inverted to determine stress and strain tensors. The analysis revealed a complex kinematic response of the eastern flank dominated by fast stress propagation and reorientation. We hypothesize that a vertical dike intruded the southern flank, generating an extensional regime that triggered a radial intrusion in the northeast sector of the volcano. The combined effects gave rise to a rotation of the stress tensor that controlled the activation of the Pernicana fault system. The volcanic and tectonic interactions produced a second reorientation of the stress tensor, causing a structural response in the southeast lower flank. The overall result of the deformation processes observed during the eruption was an E-W extension on the eastern flank of the volcano.
    Beschreibung: Published
    Beschreibung: 4
    Beschreibung: partially_open
    Schlagwort(e): Seismology: Seismicity and seismotectonics ; Seismology: Volcano seismology ; Volcanology: Eruption mechanisms ; Volcanology: Magma migration ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 3
    Publikationsdatum: 2017-04-04
    Beschreibung: Mt Etna lies on the footwall of a large normal fault system, which cuts the eastern coast of Sicily and crosses the volcano eastern flank. These faults are responsible for both large magnitude historical earthquakes and smaller damaging seismic events, closer to the volcano. We investigate here the two-way mechanical coupling between such normal faults and Mt Etna through elastic stress transfer. The comparison between eruptive sequences and historical seismicity reveals that the large earthquakes which struck the eastern Sicily occurred after long periods of activity along the Mt Etna rift zone. The larger the erupted lava volumes, the stronger the earthquake. The smaller earthquakes located on the eastern flank of the volcano occur during periods of rift zone eruptions.We point out that the seismicity rates are well correlated with the rate of erupted lava. By modelling elastic stress changes caused by earthquakes and eruptions in a 3-D elastic half-space, we investigate their interaction. Earthquake dislocations create a vertical stress gradient along fissures oriented perpendicular to the minimum compressive stress and compress shallow reservoirs beneath the volcano. This may perturb the magmatic overpressures in the Etna plumbing system and influence the transport and storage of the magma as well as the style of the eruptions. Conversely, the large rift zone eruptions increase up to several tenths MPa the Coulomb stress along the eastern Sicily normal fault system and may promote earthquakes. We show that the seismic activity of the normal faults that cut the eastern flank of the volcano is likely to be controlled by Coulomb stress perturbations caused by the voiding of shallow reservoirs during flank eruptions.
    Beschreibung: Published
    Beschreibung: 697-718
    Beschreibung: reserved
    Schlagwort(e): Coulomb stress modelling ; earthquakes–volcanoes interaction ; historical eruptions ; Mt Etna ; stress transfer ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 4
    Publikationsdatum: 2017-04-04
    Beschreibung: We investigate the relationship between changes of the gravity field and the release of the seismic energy at Mt. Etna over a 12-year period (1994-2006), during which the volcano exhibited different eruptive patterns. Over the two sub-periods when intense gravity decreases occur, centered on the upper southeastern sector of the volcano (late-1996 to mid-1999 and late-2000 to mid-2001), the strain release curve displays neat long-term accelerations, with many hypocenters clustered in the volume containing the gravity source. Various evidences suggest that, since 1994 and until the breakout of the 2001 eruption, the eastern flank of Etna remained peripheral to the lines of rise of the magma from the deep storage to the surface. Accordingly, we hypothesize that, rather than being directly associated to the migration of the magma, the joint anomalies we found image phases of higher tensile stress on the upper southeastern sector, associated to increase in the rate of microfracturing along the NNW-SSE fracture zone. Such an increase implies a local density (gravity) decrease, and an increase in the release of seismic energy, thus explaining the correlation we observe. The second period of gravity decrease/strain release increase culminated in the breakout of the 2001 flank eruption, as a pressurized deeper magma accumulation used the inferred zone of increasing microfracturing as a path to the surface. This eruption marks an important modification in the structure of Etna’s plumbing system, as also testified by the absence of post-2001 long-term gravity changes and accelerations in the strain release curve and the neat modification of the seismicity and ground deformation patterns. Thus we prove that joint microgravity and seismic studies can allow zones of the medium experiencing an increase in the rate of microfracturing to be identified months to years before a magma batch is conveyed through them to the surface, setting off a lateral eruption.
    Beschreibung: Published
    Beschreibung: 282–292
    Beschreibung: 3.6. Fisica del vulcanismo
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): microgravity changes ; seismic strain release ; 04. Solid Earth::04.03. Geodesy::04.03.05. Gravity variations ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 5
    Publikationsdatum: 2017-04-04
    Beschreibung: We analysed the seismic activity preceding and accompanying the onset of the 2008 Mt. Etna eruption. Since January 2008, a clear seismic evidence of a magmatic unrest of the volcano was observed. Seismicity was firstly located in the southwestern sector of the volcano, at depth ranging between 10 and 20 km, along two tectonic structures (NE-SW and NNW-SSE) usually associated with deeper magmatic recharge mechanisms (Figs. 1, 2). Afterwards, the seismicity was located along the shallower portions of the main structures of the northeastern and southern flanks of the volcano(Figs. 1, 2). On May 13, 2008 an intense seismic swarm (about 230 events in 7 hours) announced the beginning of the eruption (Fig. 1, white circles). In order to provide seismological constraints to the magmatic unrest of the volcano, 336 earthquakes recorded from January 2007 to May 2008 (magnitude greater than 1.0) were selected for stress and strain tensors computation and 3D velocity structure determination. This in order to individuate possible stress variations caused by the activation of magmatic sources which can be well evidenced by 3D tomographic images.
    Beschreibung: Published
    Beschreibung: Nicolosi (CT)
    Beschreibung: open
    Schlagwort(e): Mt. Etna ; eruption ; stress strain seismic ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: Oral presentation
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  • 6
    Publikationsdatum: 2017-04-04
    Beschreibung: In this paper we report seismological evidence regarding the emplacement of the dike that fed the July 18 - August 9, 2001 lateral eruption at Mt. Etna volcano. The shallow intrusion and the opening of the eruptive fracture system, which mostly occurred during July 12, and July 18, were accompanied by one of the most intense seismic swarms of the last 20 years. A total of 2694 earthquakes (1 £ Md £ 3.9) were recorded from the beginning of the swarm (July 12) to the end of the eruption (August 9). Seismicity shows the upward migration of the dike from the basement to the relatively thin volcanic pile. A clear hypocentral migration was observed, well constraining the upwards propagation of a near-vertical dike, oriented roughly N-S, and located a few kilometers south of the summit region. Earthquake distribution and orientation of the P-axes from focal mechanisms indicate that the swarm was caused by the local stress source related to the dike intrusion.
    Beschreibung: Published
    Beschreibung: 599-608
    Beschreibung: JCR Journal
    Beschreibung: open
    Schlagwort(e): Mt. Etna ; 2001 eruption ; seismicity ; fault plane solutions ; dike intrusion ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 7
    Publikationsdatum: 2017-04-04
    Beschreibung: Eastern Sicily is one of the most high seismic and volcanic risk areas in Italy. The systematic monitoring of seismic activity in this region is carried out by means of a permanent local network, managed by the Istituto Nazionale di Geofisica e Vulcanologia - Sezione di Catania (INGV-CT). The monitoring is performed: on-line by means of automatic systems designed to detect and elaborate the earthquakes and volcanic tremor, while off-line thanks to an expert scientific staff. Skilled ”analysts” daily recognize, analyse and storage all seismic events which occur in the Eastern Sicily, providing accurate information on the time evolution of earthquake activity recorded within the seismic network. In particular, the studied area encompasses four different geodynamic domines: two volcanic areas (Etna, Aeolian Island) and two tectonic ones (Hyblean Plateau and Peloritain Mountains). The good quality of earthquakes locations, the precise and the careful storage of the data, are a fundamental basis for further and important seismological studies. In detail, the scientific staff carry out, with high precision and regularity, the following main tasks: -daily counting of the earthquakes that is possible to recognize on seismograms of continuous recordings; calculation of the duration magnitude and the cumulative seismic strain release; -earthquakes location by using Winsuds software to calculate the main hypocentral parameters stored in catalogues that can be consulted in http://www.ct.ingv.it/Sismologia/analisti/default.asp -calculation of local magnitude for all the localized earthquakes with Matlab code; -waveforms, P and S-wave readings polarities and Hypoellipse output files are stored in appropriate directories inside a Databank; the Database mainly contains the “local” events recorded within the areas of coverage and some events recorded outside the network but in adjoining areas (e.g. southern Calabria, Ionian Sea, Thyrrenian Sea); -information on the daily number of explosion-quakes, VLP and landslides recorded at Stromboli volcano and on the number of very local earthquakes recorded in proximity of La Fossa of Vulcano island; -computation of focal plane solutions using the FPFIT algorithm with the aim to evaluate nodal planes and orientation of P and T axes for earthquakes with Md  3.0. Moreover, during the main eruptive events the scientific staff, in order to alert regional and national Civil Protection authorities, furnish a detailed analysis of seismic activity (parameters of earthquake locations, epicentral maps and cross sections, focal mechanisms, seismic strain release, earthquake rate, etc…) in real time or near real time.
    Beschreibung: Published
    Beschreibung: Nicolosi (CT)
    Beschreibung: open
    Schlagwort(e): Mt. Etna ; seismic ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: Poster session
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  • 8
    Publikationsdatum: 2017-04-04
    Beschreibung: Teleseismic body waves from broadband seismic stations are used to investigate the crustal and uppermost mantle structure of Stromboli volcano through inversion of the receiver functions (RFs). First, we computed RFs in the frequency domain using a multiple-taper spectral correlation technique. Then, the nonlinear neighbourhood algorithm was applied to estimate the seismic shear wave velocity of the crust and uppermost mantle and to define the main seismic velocity discontinuities. The stability of the inversion solution was tested using a range of initial random seeds and model parameterizations. A shallow Moho, present at depth of 14.8 km, is evidence of a thinned crust beneath Stromboli volcano. However, the most intriguing and innovative result is a low S velocity layer in the uppermost mantle, below 32 km. The low S velocity layer suggests a possible partial melt region associated with the volcanism, as also recently supported by tomographic studies and petrological estimations.
    Beschreibung: Published
    Beschreibung: 386-392
    Beschreibung: 3.1. Fisica dei terremoti
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): receiver function ; Stromboli ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 9
    Publikationsdatum: 2017-04-04
    Beschreibung: Nel presente lavoro sono presentati i risultati di uno studio della sismicità dell’Etna registrata tra Luglio 2005 e Gennaio 2006. Durante tale periodo l’integrazione dei dati provenienti da un esperimento condotto attraverso l’impiego di 20 stazioni temporanee a larga banda in aggiunta alla rete permanente, costituita da 40 stazioni, ha permesso di ottenere migliori localizzazioni ipocentrali (maggior numero di letture P ed S, riduzione degli errori ipocentrali e del gap azimutale). Ciò ha consentito analisi di maggior dettaglio anche degli eventi a più bassa magnitudo (M〈2.0) che costituiscono il 75 % del campione. In particolare, si è proceduto alla rilocalizzazione degli eventi (Fig. 1) utilizzando il modello di velocità 3D di Patanè et al. (2006) e al calcolo dei meccanismi focali. La maggior parte della sismicità è localizzata sul fianco orientale del vulcano permettendo una più accurata interpretazione della dinamica di questo settore. Inoltre, la localizzazione 3D dei terremoti ha meglio evidenziato l’attività sismica lungo il Rift meridionale del vulcano relativa ad uno sciame profondo (tra 10 e 15 km) registrato nell’agosto del 2005, probabilmente correlata ad una intrusione magmatica. Infatti, tale sismicità è stata seguita nei mesi successivi da un forte incremento del tremore che, tuttavia, non ha portato nel breve termine ad alcuna eruzione. Ciò nonostante, è stato osservato che in altri periodi la sismicità lungo questo trend strutturale ha preceduto di alcuni mesi l’attività eruttiva (2001, 2002-2003 e 2008).
    Beschreibung: Published
    Beschreibung: Rome
    Beschreibung: 3.6. Fisica del vulcanismo
    Beschreibung: open
    Schlagwort(e): Mt. Etna ; seismicity ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: Oral presentation
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  • 10
    Publikationsdatum: 2017-04-04
    Beschreibung: A selected dataset of 151 events, leading the July 17–August 9, 2001 lateral eruption at Mt. Etna volcano, has been analyzed for three-dimensional hypocenter locations, focal mechanisms and stress tensor inversions. The seismic pattern provided indications for two main spatial clusters of foci located along and eastwards of the 2001 Mt. Etna eruptive fractures system. The 151 fault plane solutions (mostly strike slip) were inverted for stress tensor parameters, and space variations of seismogenic stress orientations have been identified. The stress inversion results and the axi-symmetric orientation of P-axes, in the region surrounding the modeled dike, well support the evidence of a unique stress source in agreement with the ground deformation results.
    Beschreibung: Published
    Beschreibung: 1-4
    Beschreibung: partially_open
    Schlagwort(e): Seismology: Volcano seismology ; Volcanology: Eruption mechanisms ; Volcanology: Magma migration ; Volcanology: Eruption monitoring. ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.08. Volcanology::04.08.02. Experimental volcanism ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
    Format: 490 bytes
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