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  • 1
    Electronic Resource
    Electronic Resource
    A fluid-filled fracture as possible mechanism of ground deformation at Phlegraean Fields, Italy (1984)
    Springer
    Bulletin of volcanology 47 (1984), S. 313-320 
    Details
    ISSN: 1432-0819
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Two uplift episodes have recently been recorded at Phlegraean Fields, a volcanic region near Naples (south-central Italy). The first episode occurred in 1970 and lasted up to 1972; the second has begun at the end of 1982 and is still in progress. An attempt to model the ground deformations which occurred during the 1970–1972 event is made in this paper. The source has been assumed to be a two-dimensional fluid-filled fracture, similar to a sill. A good fit with experimental data has been obtained for a short (1–2 km long) shallow (3 km deep) source and a driving pressure ranging from 60 to 210 bars. Rigidity values have been fixed at 3.5–4.0 × 1010 c.g.s., with Poisson ratio equal to 0.3. This solution which differs from previous approaches byMogi (1958) andWalsh andDecker (1971) is non-unique, but the present results are in good agreement with observed horizontal and vertical displacements. Notwithstanding the oversimplification made in assuming a homogeneous elastic semi-infinite medium, the predicted stress field seems to be in agreement with the fault-plane solutions and the pattern of epicenters determined for the uplift-seismic swarm episode that is still in progress.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01961562
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    Paper (German National Licenses)
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  • 2
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    2D seismic tomography of Somma- Vesuvius. Description of the experiment and preliminary results. (2006)
    Details
    Publication Date: 2020-12-03
    Description: A multidisciplinary project for the investigation of Mt. Vesuvius Structure was started in 1993. The core of the project is represented by a high resolution seismic tomography study by using controlled and natura1 sources. The main research objective is to investigate the feeding system of the vo1cano and to retrieve details of the upper crustal structure in the area. A first 2D using seismic experiment was performed in May 1994, with the aim of studing the feasibility of lIsing tomographic techniques for exploring the vo1cano interiors. Particularly, this experiment was designed to obtain information on the optimal sources-receivers configuration and on the depth extension of the volume sampled by shot-generated seismic waves. 66 three-component seismic stations and 16 single-component analogue instruments were installed by several Italian and French groups to record signals generated by three on-land, underground explosions. Sources and geophones were deployed along a 30-km NW-SE profile passing through the volcano crater. Receivers were placed at an average spacing of 250 m in the middle of the recording line and at 500 m outside. The arrival time data base was complemented by first P and S readings of micro earthquakes which occurred in the recent past within the volcano. The first arrival data set was preliminary used to determine the shallow structure of the volcano by applying Thurber's (1983) tomographic inversion technique. This analysis shows evidence for a high-velocity body which extends vertically from about 400 m below the crater down to at least 3000 m and for a shallow 300-500 m thick low-velocity cover which borders the edifice. Data from the distant shot show evidence for arrivals of deep reflected/converted phases and provide information on the deeper structure under the volcano. The results from the interpretation of 2D data are used for planning a 3D tomographic survey which will be cauied out in 1996.
    Description: JCR Journal
    Description: open
    Keywords: Vesuvius ; tomography ; 04. Solid Earth::04.02. Exploration geophysics::04.02.06. Seismic methods ; 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
    Format: 5573128 bytes
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  • 3
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    Abruzzo, Italy, Earthquakes of April 2009: Heterogeneous Fault-Slip Models and Stress Transfer from Accurate Inversion of ENVISAT-InSAR Data (2012)
    Details
    Publication Date: 2020-12-15
    Description: The seismic sequence that occurred in the Abruzzo Apennines near L’Aquila (Italy) in April 2009 caused extensive damage and a large number of casualties (more than 300). The earthquake struck an area in the Italian Apennines chain where several faults, belonging to adjacent seismotectonic domains, create a complex tectonic regime resulting from the interaction among regional stress buildup, local stress changes caused by individual earthquakes, and viscous-elastic stress relaxation. Understanding such complex interaction in the Apennines can lead to a large step forward in the seismic risk mitigation in Italy. The Abruzzo earthquake has been very well recorded by interferometric synthetic aperture radar (InSAR) data, much better than the first Italian earthquake ever recorded by satellites, namely, the 1997 Umbria–Marche earthquake. ENVISAT (ENVIronmental SATellite) data for the Abruzzo earthquake are, in fact, very clear and allow an accurate reconstruction of the faulting mechanism. We present here an accurate inversion of vertical deformation data obtained by ENVISAT images, aimed to give a detailed reconstruction of the fault geometry and slip distribution. The resulting fault models are then used to compute, by a suitable theoretical model based on the elastic dislocation theory, the stress changes induced on the neighboring faults. The correlation of the subsequent mainshocks and aftershocks of the Abruzzo sequence with the volumes undergoing increasing Coulomb stress clearly evidence the triggering effect of coseismic stress changes on further seismicity. Moreover, this analysis put in evidence which seismotectonic domains have been more heavily charged by stress released by the Abruzzo mainshocks. The most important faults significantly charged by the Abruzzo sequence belong to the Sulmona and Avezzano tectonic domains. Taking into account the average regional stress buildup in the area, the positive Coulomb stress changes caused by this earthquake can be seen as anticipating the next earthquakes in the neighboring domains of 15–20 yr.
    Description: Published
    Description: 2340–2354
    Description: JCR Journal
    Description: restricted
    Keywords: Earthquakes of April 2009 ; 04. Solid Earth::04.07. Tectonophysics::04.07.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 4
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    3-D Modelling of Campi Flegrei Ground Deformations: Role of Caldera Boundary Discontinuities (2006)
    Birkhauser Verlag
    Details
    Publication Date: 2017-04-04
    Description: Campi Flegrei is a caldera complex located west of Naples, Italy. The last eruption occurred in 1538, although the volcano has produced unrest episodes since then, involving rapid and large ground movements (up to 2 m vertical in two years), accompanied by intense seismic activity. Surface ground displacements detected by various techniques (mainly InSAR and levelling) for the 1970 to 1996 period can be modelled by a shallow point source in an elastic half-space, however the source depth is not compatible with seismic and drill hole observations, which suggest a magma chamber just below 4 km depth. This apparent paradox has been explained by the presence of boundary fractures marking the caldera collapse. We present here the first full 3-D modelling for the unrest of 1982–1985 including the effect of caldera bordering fractures and the topography. To model the presence of topography and of the complex caldera rim discontinuities, we used a mixed boundary elements method. The a priori caldera geometry is determined initially from gravimetric modelling results and refined by inversion. The presence of the caldera discontinuities allows a fit to the 1982–1985 levelling data as good as, or better than, in the continuous half-space case, with quite a different source depth which fits the actual magma chamber position as seen from seismic waves. These results show the importance of volcanic structures, and mainly of caldera collapses, in ground deformation episodes.
    Description: Published
    Description: 1329-1344
    Description: partially_open
    Keywords: Campi Flegrei ; deformations ; caldera ; 3-D ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations ; 04. Solid Earth::04.03. Geodesy::04.03.08. Theory and Models ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
    Format: 478 bytes
    Format: 1671146 bytes
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  • 5
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    Bayesian inversion of 1994-1998 vertical displacements at Mt Etna: evidence for magma intrusion (2006)
    Blackwell publishing
    Details
    Publication Date: 2017-04-04
    Description: We have developed a Bayesian method for the inversion of static ground deformations at volcanic areas.
    Description: Published
    Description: 935-946
    Description: partially_open
    Keywords: Bayesian inversion ; deformation ; Geodesy ; magma ; Mt Etna ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations ; 04. Solid Earth::04.03. Geodesy::04.03.06. Measurements and monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
    Format: 473 bytes
    Format: 827257 bytes
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  • 6
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    Lithospheric rheology in southern Italy inferred from postseismic viscoelastic relaxation following the 1980 Irpinia earthquake (2006)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: Postseismic relaxation is modeled for the Irpinia earthquake, which struck southern Italy in 1980. Our goal is to understand the mechanism of surface deformation due to stress relaxation in the deep portion of the crust-lithosphere system for a shallow normal fault source and to infer the rheological properties of the lithosphere in the extensional environment of peninsular Italy. The modeling is carried out within the framework of our normal mode viscoelastic theory at high spatial resolution in order to accurately resolve the vertical surface displacements for a seismic source. The slip distribution over the faults is first inverted from coseismic leveling data, the misfit between observed and modeled vertical displacements being minimized by means of the L2 norm. Slip distribution is then used within the viscoelastic model to invert for the viscosities of the lower crust and generally of the lithosphere. Inversion is based on leveling data sampled along three lines crossing the epicentral area. Postseismic deformation in the Irpinia area is characterized by a broad region of crust upwarping in the footwall of the major fault and downwarping in the hanging wall that is responsible for the long-wavelength features of the vertical displacement pattern. The c2 analysis indicates that the Irpinia earthquake cannot constrain the rheology of the upper mantle but only of the crust; a full search in the viscosity spaces makes it possible to constrain the crustal viscosity to values of the order of 1019 Pa s, in agreement with previous studies carried out in different tectonic environments.
    Description: Published
    Description: 1-16
    Description: partially_open
    Keywords: Lithospheric rheology ; Irpinia earthquake ; 04. Solid Earth::04.01. Earth Interior::04.01.05. Rheology ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
    Format: 419 bytes
    Format: 623618 bytes
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  • 7
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    Monitoraggio del bradisismo del bradisismo flegreo, nel periodo maggio 2004 - marzo 2006, attraverso misure CGPS e di livellazione. (2007)
    Details
    Publication Date: 2017-04-04
    Description: in the file
    Description: Unpublished
    Description: bolzano
    Description: open
    Keywords: NONE ; 04. Solid Earth::04.03. Geodesy::04.03.06. Measurements and monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Conference paper
    Format: 1080510 bytes
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  • 8
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    Independent component analysis as a tool for ground deformation analysis (2007)
    Blackwell
    Details
    Publication Date: 2017-04-04
    Description: Independent component analysis (ICA) is a recent and well-known technique used to separate mixtures of signals. This technique has been applied to the ground deformation time-series recorded at the permanent GPS network of the Osservatorio Vesuviano—INGV in order to characterize the deformation background level in the Neapolitan volcanic area. The analysis revealed the presence of five independent periodic signals common at all the GPS stations; some of them are interpreted as effects of earth tides. The residual signal at each station represent the local ground deformation. Unfortunately the ICA cannot provide the absolute amplitude of the components, indeed we are not able to obtain a residual amplitude at each station. Then we used a stationarity analysis in order to investigate the eventual presence of local transient deformations. The ICA technique combined with the stationarity analysis has shown to be a very interesting tool for individuating ground deformation trends and could be very useful in volcanic areas monitoring.
    Description: Published
    Description: 1305–1310
    Description: 1.3. TTC - Sorveglianza geodetica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: independent component analysis ; ground deformationin ; signal processing ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.01. Computational geophysics::05.01.04. Statistical analysis
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 9
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    ANALISI DELLE COMPONENTI INDIPENDETI (ICA) NELLO STUDIO DELLE DEFORMAZIONI DEL SUOLO IN AREE VULCANICHE (2007)
    Details
    Publication Date: 2017-04-04
    Description: Independent component analysis (ICA) is a recent and well-known technique used to separate mixtures of signals. This technique has been applied to the ground deformation time-series recorded at the permanent GPS network of the Osservatorio Vesuviano-INGV in order to characterize the deformation background level in the Neapolitan volcanic area. The analysis revealed the presence of five independent periodic signals common at all the GPS stations; some of them are interpreted as effects of earth tides. The residual signal at each station represent the local ground deformation. Unfortunately the ICA cannot provide the absolute amplitude of the components, indeed we are not able to obtain a residual amplitude at each station. Then we used a stationarity analysis in order to investigate the eventual presence of local transient deformations. The ICA technique combined with the stationarity analysis has shown to be a very interesting tool for individuating ground deformation trends and could be very useful in volcanic areas monitoring.
    Description: Published
    Description: Centro Congressi Lingotto, Torino
    Description: open
    Keywords: (ICA) ; deformazioni del suolo ; aree vulcaniche ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.01. Computational geophysics::05.01.04. Statistical analysis
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Conference paper
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  • 10
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    The Campi Flegrei caldera: unrest mechanisms and hazards (2007)
    Geological Society of America
    Details
    Publication Date: 2017-04-04
    Description: In the last four decades, Campi Flegrei caldera has been the world’s most active caldera characterized by intense unrest episodes involving huge ground deformation and seismicity, but, at the time of writing, has not culminated in an eruption. We present a careful review, with new analyses and interpretation, of all the data and recent research results. We deal with three main problems: the tentative reconstruction of the substructure; the modelling of unrest episodes to shed light on possible pre-eruptive scenarios; and the probabilistic estimation of the hazards from explosive pyroclastic products. The results show, for the first time at a volcano, that a very peculiar mechanism is generating episodes of unrest, involving mainly activation of the geothermal system from deeper magma reservoirs. The character and evolution of unrest episodes is strongly controlled by structural features, like the ring-fault system at the borders of the caldera collapse. The use of detailed volcanological, mathematical and statistical procedures also make it possible to obtain a detailed picture of eruptive hazards in the whole Neapolitan area. The complex behaviour of this caldera, involving interaction between magmatic and geothermal phenomena, sheds light on the dynamics of the most dangerous types of volcanoes in the world.
    Description: Published
    Description: 25-45
    Description: open
    Keywords: NONE ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
    Format: 684147 bytes
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