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  • 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas  (51)
  • 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics  (36)
  • Elsevier  (67)
  • American Geophysical Union  (12)
  • Seismological Society of America  (2)
  • Irkutsk : Ross. Akad. Nauk, Sibirskoe Otd., Inst. Zemnoj Kory
  • Krefeld : Geologischer Dienst Nordhein-Westfalen
  • 2005-2009  (81)
Collection
Keywords
Publisher
Years
Year
  • 1
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    Present-day stress-field modelling of southern Italy constrained by stress and GPS data (2009)
    Elsevier
    Details
    Publication Date: 2020-11-16
    Description: The present-day tectonic setting of the Italian peninsula is very complex and involves competing geodynamic processes. In this context, southern peninsular Italy is characterised by extension along the Apenninic belt and in the Tyrrhenian margin and by transpression in the Apulia-Gargano region. The extension is well defined by means of geological, seismological, and contemporary stress data. For the latter only few data are available in the Apulia-Gargano region, leaving the state of stress in that area unresolved. Here we develop a finite-element model of the southern Italian region in order to predict the contemporary stress field. Our model predictions are constrained by model-independent observations of the orientation of maximum horizontal stress (SHmax), the tectonic regime, and the horizontal velocities derived from GPS observations. We performed a blind test with 31 newly acquired SHmax orientations in the Southern Apennines. These new data come from the analysis of borehole breakouts performed in 46 deep oil exploration wells ranging in depth from 1300 to 5500 m. The model results agree with the stress data that define a prevailing NW-SE SHmax orientation along the Apenninic belt and foredeep and thus are capable to predict the stress field where no stress information is available. We first analyse how much model predictions, based on older data, deviate from present-day stress data and then recalibrate the models based on our new stress data, giving insight into the resolution of both models and data. In the studied region, which is affected by low deformation rates, we find that geodetic data alone cannot resolve such low levels of deformation due to the high relative measurement errors. We conclude that both GPS and stress data are required to constrain model results.
    Description: This research was supported by the Italian Presidenza del Consiglio dei Ministri - Dipartimento della Protezione Civile (DPC) through the INGV-DPC project S1.
    Description: Published
    Description: 193-204
    Description: 2T. Deformazione crostale attiva
    Description: JCR Journal
    Description: open
    Keywords: Neotectonics ; Borehole-breakouts ; Southern Apennines ; Finite-element models ; 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::04.07. Tectonophysics::04.07.05. Stress ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
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    Chronology of the 2007 eruption of Stromboli and the activity of the Scientific Synthesis Group (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: On 27 February 2007, at 12.49 GMT, a new eruption of Stromboli took place with the effusion of a lava flow from a fracture cutting the flank of the NE cone, which rapidly reached the sea. The eruption had been heralded by an increase in the amplitude of tremor and flank movement since at least the 14th of February. Short-term precursors were an increase in the rate of occurrence of small landslides within the “Sciara del Fuoco” scar on the North-western flank of the volcano. A new effusive vent opened at 18.30 GMT on the Sciara del Fuoco at an height of 400 m asl. The new lava emission caused the sudden termination of the summit flow and initiated a period of non-stationary lava outpouring which ended on 2 April, 2007. The eruption has been characterized by a rapid decrease in the eruption rate after the first days and subsequently by episodic pulse increases. On the 15th of March, the increase in lava outpouring, monitored by a thermal camera, heralded by 9 min the occurrence of a violent paroxysmal explosion with the formation of an impulsive eruption column and the emission of small pumices mingled with black scoriae. The pumice had a bulk composition similar to that of the lava and of the black scoriae, but with a distinct lower content of phenocrysts. A similar feature has been repeatedly observed during the major explosive paroxysms of Stromboli. Short term precursors of the paroxysm were recorded by strainmeter and tiltmeter stations. The volcano monitoring activity has been made by a joint team of researchers from the INGV sections of Catania, Napoli, Palermo and Rome, along with researchers from the Universities of Florence, Pisa, Roma Tre, and Palermo. The scientific activity was coordinated by a Synthesis Group made up by scientists responsible for the different monitoring techniques of INGV and Universities and by the volcanic experts of Commissione Nazionale Grandi Rischi of the Prime Minister Office (Civil Protection Department). The group made a daily evaluation of the state of the volcano and transmitted its recommendations to the Civil Protection Department (DPC). Several prevention measures were adopted by DPC, the main of which were the evacuation of the coast zone when strong acceleration of the Sciara del Fuoco slope motion (occurred twice) could led to a dangerous tsunami by flank collapse (as last occurred on 30 December 2002) and four days before the 15 March paroxysm when access was prohibited to the part of the volcano above 290 m asl.
    Description: Published
    Description: 123–130
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: JCR Journal
    Description: reserved
    Keywords: Stromboli volcano ; 2007 eruption ; scientific emergency management ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 3
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    Deformation and eruptions at Mt. Etna (Italy): A lesson from 15 years of observations (2009)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: Volcanoes deform as a consequence of the rise and storage of magma; once magma reaches a critical pressure, an eruption occurs. However, how the edifice deformation relates to its eruptive behavior is poorly known. Here, we produce a joint interpretation of spaceborne InSAR deformation measurements and volcanic activity at Mt. Etna (Italy), between 1992 and 2006. We distinguish two volcano-tectonic behaviors. Between 1993 and 2000, Etna inflated with a starting deformation rate of 1 cm yr 1 that progressively reduced with time, nearly vanishing between 1998 and 2000; moreover, low-eruptive rate summit eruptions occurred, punctuated by lava fountains. Between 2001 and 2005, Etna deflated, feeding higher-eruptive rate flank eruptions, along with large displacements of the entire East-flank. These two behaviors, we suggest, result from the higher rate of magma stored between 1993 and June 2001, which triggered the emplacement of the dike responsible for the 2001 and 2002–2003 eruptions. Our results clearly show that the joint interpretation of volcano deformation and stored magma rates may be crucial in identifying impending volcanic eruptions.
    Description: This work was partly funded by INGV and the Italian DPC and was supported by ASI, the Preview Project and CRdC-AMRA. DPC-INGV Flank project providing the funds for the publication fees.
    Description: Published
    Description: L02309
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 1.10. TTC - Telerilevamento
    Description: 3.6. Fisica del vulcanismo
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: 4.5. Degassamento naturale
    Description: JCR Journal
    Description: partially_open
    Keywords: deformation ; eruptions ; Mt. Etna ; eruptive cycle ; InSAR ; 04. Solid Earth::04.01. Earth Interior::04.01.99. General or miscellaneous ; 04. Solid Earth::04.01. Earth Interior::04.01.02. Geological and geophysical evidences of deep processes ; 04. Solid Earth::04.03. Geodesy::04.03.99. General or miscellaneous ; 04. Solid Earth::04.03. Geodesy::04.03.06. Measurements and monitoring ; 04. Solid Earth::04.03. Geodesy::04.03.07. Satellite geodesy ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.07. Tectonophysics::04.07.99. General or miscellaneous ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics ; 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::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 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)
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  • 4
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    Dike propagation in volcanic edifices: Overview and possible developments (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Eruptions are fed by dikes; therefore, better knowledge of dike propagation is necessary to improve our understanding of how magma is transferred and extruded at volcanoes. This study presents an overview of dike patterns and the factors controlling dike propagation within volcanic edifices. Largely based on published data, three main types of dikes (regional, circumferential and radial) are illustrated and discussed. Dike pattern data from 25 volcanic edifices in different settings are compared to derive semi-quantitative relationships between the topography (relief, shape, height, and presence of sector collapses) of the volcano, tectonic setting (presence of a regional stress field), and mean composition (SiO2 content). The overview demonstrates how dike propagation in a volcano is not a random process; rather, it depends from the following factors (listed in order of importance): the presence of relief, the shape of the edifice and regional tectonic control. We find that taller volcanoes develop longer radial dikes, whose (mainly lateral) propagation is independent of the composition of magma or the aspect ratio of the edifice. Future research, starting from these preliminary evaluations, should be devoted to identifying dike propagation paths and likely locations of vent formation at specific volcanoes, to better aid hazards assessment.
    Description: Partly fundedwith DPC-INGVfunds (LAVAProject).
    Description: Published
    Description: 67–77
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.2. Tettonica attiva
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: dikes ; volcanoes ; topography ; tectonic setting ; eruptions ; 03. Hydrosphere::03.04. Chemical and biological::03.04.02. Carbon cycling ; 04. Solid Earth::04.01. Earth Interior::04.01.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.07. Tectonophysics::04.07.99. General or miscellaneous ; 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.02. Data dissemination::05.02.99. General or miscellaneous ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions ; 05. General::05.08. Risk::05.08.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 5
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    Intrusion of eccentric dikes: The case of the 2001 eruption and its role in the dynamics of Mt. Etna volcano (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The 2001 eruption represents one of the most studied events both from volcanological and geophysical point of view on Mt. Etna. This eruption was a crucial event in the recent dynamics of the volcano, marking the passage from a period (March 1993–June 2001) of moderate stability with slow, continuous flank sliding and contemporaneous summit eruptions, to a period (July 2001 to present) of dramatically increased flank deformations and flank eruptions. We show new GPS data and high precision relocation of seismicity in order to demonstrate the role of the 2001 intrusive phase in this change of the dynamic regime of the volcano. GPS data consist of two kinematic surveys carried out on 12 July, a few hours before the beginning of the seismic swarm, and on 17 July, just after the onset of eruptive activity. A picture of the spatial distribution of the sin-eruptive seismicity has been obtained using the HypoDD relocation algorithm based on the double-difference (DD) technique. Modeling of GPS measurements reveals a southward motion of the upper southern part of the volcano, driven by a NNW–SSE structure showing mainly left-lateral kinematics. Precise hypocenter location evidences an aseismic zone at about sea level, where the magma upraise was characterized by a much higher velocity and an abrupt westward shift, revealing the existence of a weakened or ductile zone. These results reveal how an intrusion of a dike can severely modify the shallow stress field, triggering significant flank failure. In 2001, the intrusion was driven by a weakened surface, which might correspond to a decollement plane of the portion of the volcano affected by flank instability, inducing an additional stress testified by GPS measurements and seismic data, which led to an acceleration of the sliding flanks.
    Description: This work was funded by the Istituto Nazionale di Geofisica e Vulcanologia and by the Dipartimento per la Protezione Civile (Italy).
    Description: Published
    Description: 78–86
    Description: 1.3. TTC - Sorveglianza geodetica delle aree vulcaniche attive
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.2. Tettonica attiva
    Description: 3.6. Fisica del vulcanismo
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: reserved
    Keywords: stress release ; dike ; volcano-tectonics ; flank instability ; Mt. Etna ; instrumental monitoring ; 04. Solid Earth::04.01. Earth Interior::04.01.99. General or miscellaneous ; 04. Solid Earth::04.01. Earth Interior::04.01.02. Geological and geophysical evidences of deep processes ; 04. Solid Earth::04.02. Exploration geophysics::04.02.99. General or miscellaneous ; 04. Solid Earth::04.03. Geodesy::04.03.99. General or miscellaneous ; 04. Solid Earth::04.03. Geodesy::04.03.07. Satellite geodesy ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.07. Tectonophysics::04.07.99. General or miscellaneous ; 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.02. Data dissemination::05.02.99. General or miscellaneous ; 05. General::05.02. Data dissemination::05.02.02. Seismological data ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 6
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    Pressure dependence of viscosity of rhyolitic melts (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Viscosity of silicate melts is a critical property for understanding volcanic and igneous processes in the Earth. We investigate the pressure effect on the viscosity of rhyolitic melts using two methods: indirect viscosity inference from hydrous species reaction in melts using a piston cylinder at pressures up to 2.8 GPa and direct viscosity measurement by parallel-plate creep viscometer in an internally-heated pressure vessel at pressures up to 0.4 GPa. Comparison of viscosities of a rhyolitic melt with 0.8 wt% water at 0.4 GPa shows that both methods give consistent results. In the indirect method, viscosities of hydrous rhyolitic melts were inferred based on the kinetics of hydrous species reaction in the melt upon cooling (i.e., the equivalence of rheologically defined glass transition temperature and chemically defined apparent equilibrium temperature). The cooling experiments were carried out in a piston-cylinder apparatus using hydrous rhyolitic samples with 0.8–4 wt% water. Cooling rates of the kinetic experiments varied from 0.1 K/s to 100 K/s; hence the range of viscosity inferred from this method covers 3 orders of magnitude. The data from this method show that viscosity increases with increasing pressure from 1 GPa to 3 GPa for hydrous rhyolitic melts with water content 0.8 wt% in the high viscosity range. We also measured viscosity of rhyolitic melt with 0.13 wt% water using the parallel-plate viscometer at pressures 0.2 and 0.4 GPa in an internally-heated pressure vessel. The data show that viscosity of rhyolitic melt with 0.13 wt% water decreases with increasing pressure. Combining our new data with literature data, we develop a viscosity model of rhyolitic melts as a function of temperature, pressure and water content.
    Description: NSF Grants EAR-0537598 and EAR-0711050
    Description: Published
    Description: 3680-3693
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: JCR Journal
    Description: reserved
    Keywords: viscosity ; rhyolite ; water species ; pressure ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 7
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    Nitrogen Isotopes in Volcanic Fluids of Different Geodynamic Settings (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Nitrogen isotopes , N2/36Ar and 3He/4He were measured in volcanic fluids within different geodynamic settings. Subduction zones are represented by Aeolian archipelago, Mexican volcanic belt and Hellenic arc, spreading zones – by Socorro island in Mexico and Iceland and hot spots by Iceland and Islands of Cabo Verde. The δ15N values, corrected for air contamination of volcanic fluids, discharged from Vulcano Island (Italy), highlighted the presence of heavy nitrogen (around +4.3 ±0.5‰). Similar 15N values (around +5‰), have been measured for the fluids collected in the Jalisco Block, that is a geologically and tectonically complex forearc zone of the northwestern Mexico [1]. Positive values (15N around +3‰) have been also measured in the volcanic fluids discharged from Nysiros island located in the Ellenic Arc characterized by subduction processes. All uncorrected data for the Socorro island are in the range of -1 to -2‰. The results of raw nitrogen isotope data of Iceland samples reveal more negative isotope composition (about -4.4‰). On the basis of the non-atmospheric N2 fraction (around 50%) the corrected data of 15N for Iceland are around -16‰, very close to the values proposed by [2]. In a volcanic gas sample from Fogo volcano (Cabo Verde islands) we found a very negative value: -9.9‰ and -15‰ for raw and corrected values, respectively.
    Description: Geochimica et Cosmochimica Acta
    Description: Published
    Description: Davos, Switzerland
    Description: 2.4. TTC - Laboratori di geochimica dei fluidi
    Description: open
    Keywords: Nitrogen Isotopes ; Helium Isotopes ; Volcanic fluids ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 8
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    Geochemical and B–Sr–Nd isotopic evidence for mingling and mixing processes in the magmatic system that fed the Astroni volcano (4.1–3.8 ka) within the Campi Flegrei caldera (southern Italy) (2009)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The Astroni volcano was built through seven eruptions that generated pyroclastic deposits and lava domes within the Campi Flegrei caldera (southern Italy) 4.1–3.8 ka BP. Whole-rock geochemical and B–Sr–Nd isotopic investigations were carried out on representative samples of all seven eruptions. The products vary from tephriphonolites to phonolites, and from latites to trachytes. They show textural, mineralogical and isotopic evidence of disequilibrium, including distinct clinopyroxene populations, rounded and/or resorbed plagioclase and alkali-feldspar, and reverse-zoned phenocrysts of all these mineral phases. The Sr, Nd and B isotopic composition of whole rocks is variable and correlated with the degree of chemical evolution, suggesting open-system processes in addition to fractional crystallisation. Moreover, significant Sr-isotopic disequilibrium between the phenocrysts and glass has been documented for one sample. The chemostratigraphy of the products indicates that Astroni eruptions 1 through 5 were fed by magmas of trachytic to phonolitic composition that were less enriched in radiogenic Sr and 11B up-section. This variability has been interpreted as the result of mingling between at least two distinct magmatic endmembers, one more evolved and the other less evolved. Another heterogeneous batch of magma, resulting from almost complete mixing between the same two end-members, was drained during eruptions 6 and 7. The more evolved end-member, characterised by 87Sr/86Sr≥0.7075, 143Nd/144Nd≤0.51247 and δ11B≥−8‰, was very similar to the magma that fed the final phases of the Agnano–Monte Spina eruption, which occurred a few centuries earlier in the Astroni vent area. The less evolved end-member had 87Sr/ 86Sr≤0.70726, 143Nd/144Nd≥0.51251 and δ11B≤10‰, and was likely derived by fractional crystallisation of a mantle-derived magma. An abrupt decrease in both the Sr isotope ratio and the Th content, detected at the transition between Unit 4 and 5, suggests that another magma with a 87Sr/86Sr ratio intermediate between those of the two identified end-members may have been involved in Astroni activity. The more evolved endmember is interpreted as a residue of the Agnano–Monte Spina eruption that was invaded by either the intermediate or the less evolved magmatic end-member, promoting mingling and triggering Astroni activity. This study of Astroni provides insights for both short- and long-term volcanic hazard assessment, as the Astroni volcano is the best example of a very close sequence of eruptions from the same vent area in the Campi Flegrei caldera.
    Description: Published
    Description: 135–151
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: JCR Journal
    Description: reserved
    Keywords: Campi Flegrei caldera ; B–Sr–Nd isotope geochemistry ; Magma mingling/mixing ; Chemostratigraphy ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 9
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    The Paganica Fault and surface coseismic ruptures caused by the 6 april 2009 earthquake (L’Aquila, central Italy) (2009)
    Seismological Society of America
    Details
    Publication Date: 2022-06-14
    Description: On 6 April 2009, at 01:32 GMT, an Mw 6.3 seismic event hit the central Apennines, severely damaging the town of L’Aquila and dozens of neighboring villages and resulting in approximately 300 casualties (Istituto Nazionale di Geofisica e Vulcanologia, http://www.ingv.it; MedNet, http://mednet.rm.ingv.it/proce- dure/events/QRCMT/090406_013322/qrcmt.html). This earth- quake was the strongest in central Italy since the devastating 1915 Fucino event (Mw 7.0). The INGV national seismic net- work located the hypocenter 5 km southwest of L’Aquila, 8–9 km deep. Based on this information and on the seismotectonic framework of the region, earthquake geologists traveled to the field to identify possible surface faulting (Emergeo Working Group 2009a, 2009b). The most convincing evidence of pri- mary surface rupture is along the Paganica fault, the geometry of which is consistent with seismological, synthetic aperture radar (SAR) and GPS data. Investigation of other known nor- mal faults of the area, i.e., the Mt. Pettino, Mt. San Franco, and Mt. Stabiata normal faults suggested that these structures were not activated during the April 6 shock (Emergeo Working Group 2009a, 2009b). In this report, we first describe the seismotectonic frame- work of the area, and then we present the field information that supports the occurrence of surficial displacement on the Paganica fault.
    Description: Published
    Description: 940-950
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: open
    Keywords: Surface coseismic ruptures ; Paganica Fault ; earthquake ; 04. Solid Earth::04.04. Geology::04.04.01. Earthquake geology and paleoseismology ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 10
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    Experimental solidification of anhydrous latitic and trachytic melts at different cooling rates: the role of nucleation kinetics (2008)
    Elsevier
    Details
    Publication Date: 2020-10-29
    Description: Two sets of cooling experiments were run at atmospheric conditions for two anhydrous starting latitic and trachytic melts: 1) five cooling rates (25, 12.5, 3, 0.5, and 0.125 °C/min) between 1300° and 800 °C, and 2) a 11 0.5 °C/min cooling rate from 1300 °C with quench temperatures at 1200°, 1100°, 1000° and 900 °C. Trachytic run-products are invariably glassy. Nucleation is also suppressed in the latitic run-products at the three highest 13 cooling rates. Conversely, in the 0.5 and 0.125 °C/min runs, latites have a crystal content of 90 vol.%. The 14 phases are: plagioclase, clinopyroxene, glass and iron-bearing oxide (in order of abundance). The variable 15 quench temperatures, investigated by coupling experiments with Pt-wire and Pt- capsule sample containers inset 2,again did not produce crystallization of trachyte, whereas latitic samples are characterized by 10 vol.% of oxides, pyroxenes and plagioclase (in order of appearance), at temperature b1000 °C. Effects of (preferential) heterogeneous nucleation on sample holders, of superheating degree, and chemical species loss during cooling are absent for both melt compositions. The difference of solidification paths between these two silicate melts can be ascribed only to their small chemical differences. In comparison with calculated equilibrium conditions all the experimental latitic and trachytic run-products revealed strong kinetic effects, interpretable in the light of the nucleation theory. The glass- forming ability (GFA) of trachyte is higher, whereas their critical cooling rate (Rc) is lower (b0.125 °C/min), in comparison to latitic melts (RcN0.5 °C/min). The experimental results carried out in this study can be applied to lava flows and domes; trachytic lavas are able to flow for longer period with respect to latitic ones in a metastable condition. Glass-rich terrestrial lavas, i.e. obsidians, can be the result of sluggish nucleation kinetics due to the relative high polymerisation of evolved silicate melts.
    Description: Published
    Description: 91-101
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: crystallization ; lava flows ; 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::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 05. General::05.02. Data dissemination::05.02.02. Seismological data
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  • 11
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    Mechanisms for ground-surface fracturing and incipient slope failure associated with the 2001 eruption of Mt. Etna, Italy: analysis of ephemeral field data (2008)
    Elsevier
    Details
    Publication Date: 2020-11-26
    Description: During the July^August 2001 eruption of Mt. Etna development of extensional fractures/faults and grabens accompanied magma intrusion and subsequent volcanic activity. During the first days of the eruption, we performed an analysis of attitude, displacement and propagation of fractures and faults exposed on the ground surface in two sites, Torre del Filosofo and Valle del Leone, located along the same fracture system in the region surrounding the Valle del Bove depression on the eastern flank of Mt. Etna. Fractures and faults formed as the consequence of a shallow intruding dyke system that fed the several volcanic centres developed along the fracture system. The investigated sites differ in slope attitude and in geometrical relationships between fractures and slopes. In particular, the fracture system propagated parallel to the gentle slope (67‡ dip) in the Torre del Filosofo area, and perpendicular to the steep slope (V25‡ dip) in the Valle del Leone area. In the Torre del Filosofo area, slight graben subsidence and horizontal extension of the ground surface by about 3 m were recorded. In the Valle del Leone area, extensional faulting forming a larger and deeper graben with horizontal extension of the ground surface by about 10 m was recorded. For the Valle del Leone area, we assessed a downhill dip of 14‡ for the graben master fault at the structural level beneath the graben where the fault dip shallows. These results suggest that dyke intrusion at Mount Etna, and particularly in the region surrounding the Valle del Bove depression, may be at the origin of slope failure and subsequent slumps where boundary conditions, i.e. geometry of dyke, slope dip and initial shear stress, amongst others, favour incipient failures.
    Description: Published
    Description: 281-294
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.2. Tettonica attiva
    Description: 3.5. Geologia e storia dei sistemi vulcanici
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: dykes ; extensional fractures ; grabens ; slope failures ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
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  • 12
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    Volcanology and magma geochemistry of the present-day activity: constraints on the feeding system (2008)
    American Geophysical Union
    Details
    Publication Date: 2020-12-14
    Description: Stromboli volcano is famous in the scientific literature for its persistent state of activity, which began about 1500 years ago and consists of continuous degassing and mild intermittent explosions (normal Strombolian activity). Rare lava emissions and sporadic more violent explosive episodes (paroxysms) also occur. Since its formation, the present-day activity has been dominated by the emission of two basaltic magmas, differing chiefly in their crystal and volatile contents, whose characteristics have remained constant until now. The normal Strombolian activity and lava effusions are fed by a crystal-rich, degassed magma, stored within the uppermost part of the plumbing system, whereas highly vesicular, crystal-poor light-colored pumices are produced during paroxysms testifying to the ascent of volatile-rich magma batches from deeper portions of the magmatic system. Mineralogical, geochemical, and isotopic data, together with data on the volatile contents of magmas, are presented here with the aim of discussing (1) the relationships between the different magma batches erupted at Stromboli, (2) the mechanisms of their crystallization and transfer, (3) the plumbing system and triggering mechanisms of Strombolian eruptions.
    Description: Unpublished
    Description: 20
    Description: 3.5. Geologia e storia dei sistemi vulcanici
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: reserved
    Keywords: Stromboli volcano ; Basaltic explosive activity ; Basaltic pumice ; Plumbing system ; 04. Solid Earth::04.04. Geology::04.04.05. Mineralogy and petrology ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
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    Type: book chapter
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  • 13
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    Volumetric observations during paroxysmal eruptions at Mount Etna: pressurized drainage of a shallow chamber or pulsed supply? (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The October 17 to November 5, 1999, eruption of Mount Etna’s Bocca Nuova crater emplaced a V15U106 m3 flow field. The eruption was characterized by 11 paroxysmal events during which intense Strombolian and lava fountain activity fed vigorous channelized PaPa flows at eruption rates of up to 120 m3 s31. Each paroxysm lasted between 75 and 450 min, and was separated by periods of less intense Strombolian activity and less vigorous (610 m3 s31) effusion. Ground-based, satellite- and model-derived volumetric data show that the eruption was characterized by two periods during which eruption rates and cumulative volume showed exponential decay. This is consistent with a scenario whereby the system was depressurized during the first eruptive period (October 17^23), repressurized during an October 24 pause, and then depressurized again during the second period (October 25^28). The imbalance between the erupted and supplied volumes mean that the two periods involved the collection of 1.5^5.7U106 m3 and 1.2^ 3.6U106 m3, respectively, or an increase in the time-averaged supply to 11.6^13.6 m3 s31 and 12.5^14.9 m3 s31. Two models are consistent with the observed episodic fountaining, derived volumetric trends and calculated volume imbalance: a magma collection model and a pulsed supply model. In the former case, depressurization of a shallow reservoir cause the observed volumetric trends and foam collapse at the reservoir roof powers fountaining. In the pulsing case, variations in magma flux account for pressurization^depressurization and supply the excess volume. Increases in rise rate and volatile flux, coupled with rapid exsolution during ascent, trigger fountaining. Limiting equations that define critical foam layer volumes and magma rise rates necessary for Hawaiian-style fountaining favor the latter model.
    Description: Published
    Description: 79-95
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.5. Geologia e storia dei sistemi vulcanici
    Description: 3.6. Fisica del vulcanismo
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: reserved
    Keywords: Etna ; lava fountaining ; eruption rates ; lava channel ; foam layers ; rise rates ; 04. Solid Earth::04.01. Earth Interior::04.01.99. General or miscellaneous ; 04. Solid Earth::04.01. Earth Interior::04.01.05. Rheology ; 04. Solid Earth::04.02. Exploration geophysics::04.02.99. General or miscellaneous ; 04. Solid Earth::04.02. Exploration geophysics::04.02.05. Downhole, radioactivity, remote sensing, and other methods ; 04. Solid Earth::04.02. Exploration geophysics::04.02.07. Instruments and techniques ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.11. Instruments and techniques ; 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::04.08.02. Experimental volcanism ; 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::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
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  • 14
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    Continuous monitoring of soil CO2 flux on Mt. Etna:The 2004–2005 eruption and the role of regional tectonics and volcano tectonics. (2008)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: The soil CO2 flux on Mt. Etna as recorded by the ETNAGAS network (an automatic system for measuring soil CO2 flux and meteorological parameters) started to increase strongly about 5 months prior to the onset of the 2004–2005 eruption and decreased a few months before the end of the eruption. Time delays in the occurrences of anomalies in soil CO2 flux at different sites in the geochemical network constrain the relationship between soil CO2 flux distributions and the tectonic framework of Etna volcano. The anomalies observed before the 2004–2005 eruption support the intrusion of new undegassed magma into the upper feeding system of the volcano (〈20 km below sea level). Magma subsequently rose slowly in the volcano conduits, thereby triggering the onset of the 2004–2005 eruption. The time delays in the occurrences of anomalies in combination with spectral analysis indicate the importance of tectonic and volcanotectonic structures in driving the ascent of deep gases within the crust. Moreover, greatest amplitude pulsations of the low-frequency components of the CO2 flux signals were correlated with the paroxystic activities of the 2004–2005 eruption. This study confirms that CO2 flux variation is a useful indicator for volcanic activity in the surveillance of the Mt. Etna and similar basaltic volcanoes.
    Description: Dipartimento Protezione Civile Ministero degli Interni
    Description: Published
    Description: B09206
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: JCR Journal
    Description: reserved
    Keywords: CO2 flux ; Continuous monitoring of soil CO2 flux ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
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  • 15
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    Vent conditions for expected eruptions at Vesuvius (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Determining consistent sets of vent conditions for next expected eruptions at Vesuvius is crucial for the simulation of the sub-aerial processes originating the volcanic hazard and the eruption impact. Herewerefer to the expected eruptive scales and conditions defined in the frame of the EC Exploris project, and simulate the dynamics of magma ascent along the volcanic conduit for sub-steady phases of next eruptions characterized by intensities of the Violent Strombolian (VS), Sub-Plinian 2 (SP2), and Sub-Plinian 1 (SP1) scale. Sets of conditions for the simulations are determined on the basis of the bulk of knowledge on the past history of Vesuvius [Cioni, R., Bertagnini, A., Santacroce, R., Andronico, D., Explosive activity and eruption scenarios at Somma–Vesuvius (Italy): towards a new classification scheme. Journal of Volcanology and Geothermal Research, this issue.]. Volatile contents (H2O and CO2) are parameterized in order to account for the uncertainty in their expected amounts for a next eruption. In all cases the flow in the conduit is found to be choked, with velocities at the conduit exit or vent corresponding to the sonic velocity in the two-phase non-equilibrium magmatic mixture. Conduit diameters and vent mixture densities are found to display minimum overlapping between the different eruptive scales, while exit gas and particle velocities, as well as vent pressures, largely overlap. Vent diameters vary from as low as about 5 m for VS eruptions, to 35–55 m for the most violent SP1 eruption scale. Vent pressures can be as low as less than 1 MPa for the lowest volatile content employed of 2 wt.% H2O and no CO2, to 7–8 MPa for highest volatile contents of 5 wt.% H2O and 2 wt.% CO2 and large eruptive scales. Gas and particle velocities at the vent range from 100–250 m/s, with a tendency to decrease, and to increase the mechanical decoupling between the phases, with increasing eruptive scale. Except for velocities, all relevant vent quantities are more sensitive to the volatile content of the discharged magma for the highest eruptive scales considered.
    Description: Published
    Description: 359-365
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: Vesuvius ; Numerical simulations ; Vent conditions ; Volcanic hazard ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 16
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    Belt bending driven by lateral bending of subducting lithospheric slab: geophysical evidences from the northern Apennines (Italy) (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Many of the mountain belts displaying a curved shape are "oroclines", i.e. are produced after progressive bending of an originally straight fold and thrust belt. The bending process was previously explained as a consequence of several possible events taking place in the crustal orogenic wedge, such as occurrence of obstacles, non-coaxial deformation, and mouvements on wrench faults. Recent paleomagnetic results from the northern Apenninic Arc document that this belt is properly an orocline and results from Late Messinian-Early Pliocene bending of a Messinian straight belt-foredeep system. Tomographic images in turn show the presence of a high-velocity body, interpreted as subducted slab, in the upper mantle beneath the northern Apennines, between 35 and 670 km depth. Down to 100 km, this body displays an arcuate shape which closely mirrors the geological outlines, while it appears to be straight (and parallel to the Messinian pre-rotated belt) at depth. We explore here the possibility that the arcuate shape of the northern Apennines is a consequence, closely following in time, on much deeper processes than previously suggested, i.e. the lateral bending of the subducting Adriatic plate.
    Description: Published
    Description: 53-64
    Description: JCR Journal
    Description: reserved
    Keywords: paleomagnetism ; seismic tomography ; Northern Apennines ; orocline ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism ; 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
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  • 17
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    Transpressive strain on the Lipari–Vulcano volcanic complex and dynamics of the “La Fossa” cone (Aeolian Islands, Sicily) revealed by GPS surveys on a dense network (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Ground deformation resulting from the last two GPS surveys carried out in March 2006 and September 2007 on the Lipari–Vulcano volcanic complex are analyzed. Data inversion was performed by Genetic Algorithms approach, using the horizontal strain measured on 258 GPS baselines, in order to avoid bias due to the ambiguity in fixing the reference system and to disregard the vertical deformation of the “La Fossa” cone. There are two networks in this area: the main Lipari–Vulcano network and the denser Vulcano–Nord one. Surveying strategies adopted for the main network during the latest surveys allowed long baselines, from Lipari and Vulcano to the surrounding permanent stations in the southern Tyrrhenian, to be processed with reliable accuracy. The fast-static strategy was instead adopted to survey the Vulcano–Nord network. Data from the main Lipari–Vulcano network has been processed in the ITRF05 frame and also in a local reference frame together with the Vulcano–Nord data. A significant Northward motion of Vulcano island with respect to the ITRF05 has been detected. This motion abruptly decreases in the northern part of Vulcano, suggesting a decoupling of the main Vulcano island from the rest of the volcanic complex. The analysis in the local reference frame evidenced a relative SSE-ward motion of Lipari and Northern part of Vulcano, with respect to the central and southern Vulcano. This comparison also highlights a local uplift of the “La Fossa” cone. In addition, a strain tensor analysis was performed, which highlighted a main NNE–SSW contraction and a minor ESE–WNW extension detected only on the southern part of Vulcano. This results are in agreement with a transpressive kinematics of the Lipari–Vulcano volcanic complex, with a main dextral component of displacement along a NW–SE striking structure.
    Description: Published
    Description: 64-70
    Description: 1.3. TTC - Sorveglianza geodetica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Volcano-tectonics ; Modeling ; ground deformation ; Tyrrhenian sea ; 04. Solid Earth::04.03. Geodesy::04.03.06. Measurements and monitoring ; 04. Solid Earth::04.03. Geodesy::04.03.07. Satellite geodesy ; 04. Solid Earth::04.03. Geodesy::04.03.08. Theory and Models ; 04. Solid Earth::04.03. Geodesy::04.03.09. Instruments and techniques ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.07. Tectonophysics::04.07.08. Volcanic arcs
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  • 18
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    Middle Pleistocene to Holocene activity of the Gondola Fault Zone (Southern Adriatic Foreland): deformation of a regional shear zone and seismotectonic implications (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Recent seismicity in and around the Gargano Promontory, an uplifted portion of the Southern Adriatic Foreland domain, indicates active E–W strike-slip faulting in a region that has also been struck by large historical earthquakes, particularly along the Mattinata Fault. Seismic profiles published in the past two decades show that the pattern of tectonic deformation along the E–W-trending segment of the Gondola Fault Zone, the offshore counterpart of the Mattinata Fault, is strikingly similar to that observed onshore during the Eocene–Pliocene interval. Based on the lack of instrumental seismicity in the south Adriatic offshore, however, and on standard seismic reflection data showing an undisturbed Quaternary succession above the Gondola Fault Zone, this fault zone has been interpreted as essentially inactive since the Pliocene. Nevertheless, many investigators emphasised the genetic relationships and physical continuity between the Mattinata Fault, a positively active tectonic feature, and the Gondola Fault Zone. The seismotectonic potential of the system formed by these two faults has never been investigated in detail. Recent investigations of Quaternary sedimentary successions on the Adriatic shelf, by means of very high-resolution seismic–stratigraphic data, have led to the identification of fold growth and fault propagation in Middle–Upper Pleistocene and Holocene units. The inferred pattern of gentle folding and shallow faulting indicates that sediments deposited during the past ca. 450 ka were recurrently deformed along the E–W branch of the Gondola Fault Zone. We performed a detailed reconstruction and kinematic interpretation of the most recent deformation observed along the Gondola Fault Zone and interpret it in the broader context of the seismotectonic setting of the Southern Apennines-foreland region. We hypothesise that the entire 180 km-long Molise–Gondola Shear Zone is presently active and speculate that also its offshore portion, the Gondola Fault Zone, has a seismogenic behaviour.
    Description: Study supported by ISMAR-CNR projects EUROSTRATAFORM (EVK3-CT-2002-00079) and “Rischi Sottomarini”(GNDT 2000–2004) and by the Project S2 funded in the framework of the 2004–2006 agreement between the Italian Department of Civil Protection and INGV (Research Unit 2.4). This is ISMAR-CNR (Bologna) contribution n. 1570.
    Description: Published
    Description: 110-121
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: reserved
    Keywords: Quaternary ; Foreland deformation ; Active fault ; Adriatic Sea ; 04. Solid Earth::04.02. Exploration geophysics::04.02.06. Seismic methods ; 04. Solid Earth::04.04. Geology::04.04.04. Marine geology ; 04. Solid Earth::04.04. Geology::04.04.10. Stratigraphy ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
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  • 19
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    Intrusion of eccentric dikes: The case of the 2001 eruption and its role in the dynamics of Mt. Etna volcano (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The 2001 eruption represents one of the most studied events both from volcanological and geophysical point of view on Mt. Etna. This eruption was a crucial event in the recent dynamic of the volcano, marking the passage from a period (March 1993 – June 2001) of moderate stability with slow, continuous flank sliding and contemporaneous summit eruptions, to a period (July 2001 to present) of dramatically increased flank deformations and flank eruptions. We show new GPS data and high precision relocation of seismicity in order to demonstrate the role of the 2001 intrusive phase in this change of the dynamic regime of the volcano. GPS data consist of two kinematic surveys carried out on 12 July, a few hours before the beginning of the seismic swarm, and on 17 July, just after the onset of eruptive activity. A picture of the spatial distribution of the sin-eruptive seismicity has been obtained using the HypoDD relocation algorithm based on the double-difference (DD) technique. Modeling of GPS measurements reveal a southward motion of the upper southern part of the volcano, driven by a NNW-SSE structure showing mainly left-lateral kinematics. Precise hypocenter location evidences an aseismic zone at about sea level, where the magma upraise was characterized by a much higher velocity and an abrupt westward shift, revealing the existence of a weakened or ductile zone. These results reveal how an intrusion of a dike can severely modify the shallow stress field, triggering significant flank failure. In 2001, the intrusion was driven by a weakened surface, which might correspond to a decollement plane of the portion of the volcano affected by flank instability, inducing an additional stress testified by GPS measurements and seismic data, which led to an acceleration of the sliding flanks.
    Description: In press
    Description: 1.1. TTC - Monitoraggio sismico del territorio nazionale
    Description: 1.3. TTC - Sorveglianza geodetica delle aree vulcaniche attive
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.2. Tettonica attiva
    Description: 3.5. Geologia e storia dei sistemi vulcanici
    Description: 3.6. Fisica del vulcanismo
    Description: 4.2. TTC - Scenari e mappe di pericolosità sismica
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: 4.4. Scenari e mitigazione del rischio ambientale
    Description: JCR Journal
    Description: reserved
    Keywords: Stress release ; Dike ; Volcano-tectonics ; Flank instability ; Mount Etna ; Instrumental monitoring ; 04. Solid Earth::04.01. Earth Interior::04.01.99. General or miscellaneous ; 04. Solid Earth::04.01. Earth Interior::04.01.02. Geological and geophysical evidences of deep processes ; 04. Solid Earth::04.02. Exploration geophysics::04.02.99. General or miscellaneous ; 04. Solid Earth::04.03. Geodesy::04.03.99. General or miscellaneous ; 04. Solid Earth::04.03. Geodesy::04.03.06. Measurements and monitoring ; 04. Solid Earth::04.03. Geodesy::04.03.07. Satellite geodesy ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.01. Earthquake geology and paleoseismology ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous ; 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::04.06.08. Volcano seismology ; 04. Solid Earth::04.07. Tectonophysics::04.07.99. General or miscellaneous ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.99. 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 ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
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  • 20
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    Structural features of the 2007 Stromboli eruption (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: On 27 February 2007, two NE–SW and NNW–SSE dike-fed effusive vents opened to the North (at 650 and 400 m above sea level, asl) of the summit craters at Stromboli, forming a fissure parallel to the inner walls of the Sciara del Fuoco (SdF) sector collapse depression. The formation of these vents was soon followed by rapid subsidence of the summit crater area. This partly obstructed the central conduit, temporarily choking the fissure and increasing the deformation of the upper part of SdF. The reactivation of the NNW–SSE vent and the opening of a new vent located at 500 m asl, fed by a second dike, released the internal pressure and surface deformation ceased. The eruption then continued again from the 400 m vent, after a summit explosion on 15 March, until ending in early April after a progressive decrease of magma output. Repeated NE–SW dike intrusions have occurred in recent years, close to the upper SE limit of the SdF. In that zone, named Bastimento, the eruptive fractures traced the discontinuities that borders the SdF, increasing the risk of triggering new sector collapse. Whereas the NE–SW trending structures lie along the regional volcanostructural trend of the Aeolian arc through Stromboli, the NNW–SSE vents are oblique to this trend and may be controlled by the anomalous stress field within the unstable flank of the SdF. Another fundamental aspect of the 2007 eruption is the collapse of the central conduit, due to the rapid and deep magma drainage linked to the opening of the 400 m vent. The intrusion of dikes and development of flank vents during the 2007 eruption could possibly have triggered catastrophic landslides and related tsunami or eruptive paroxysms, but the opening of new effusive vents released the internal pressures, diminishing the hazard.
    Description: In press
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.2. Tettonica attiva
    Description: 3.5. Geologia e storia dei sistemi vulcanici
    Description: 3.6. Fisica del vulcanismo
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: reserved
    Keywords: 2007 Stromboli eruption ; Dike-fed vent ; Volcano-Tectonics ; Conduit collapse ; Flank instability ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.07. Tectonophysics::04.07.99. General or miscellaneous ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.07. Tectonophysics::04.07.08. Volcanic arcs ; 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::04.08.08. Volcanic risk ; 05. General::05.08. Risk::05.08.99. General or miscellaneous
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  • 21
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    Comparison between different methodologies for detecting Radon in soil along an active fault: the case of the Pernicana fault system, Mt. Etna (Italy) (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Three different methodologies were used to measure Radon (222Rn) in soil, based on both passive and active detection system. The first technique consisted of Solid State Nuclear Track Detectors (SSNTD), CR-39 type, and allowed integrated measurements. The second one consisted of a portable device for short time measurements. The last consisted of a continuous measurement device for extended monitoring, placed in selected sites. Soil 222Rn activity was measured together with soil Thoron (220Rn) and soil carbon dioxide (CO2) efflux, and it was compared with the content of radionuclides in the rocks. Two different soil gas horizontal transects were investigated across the Pernicana fault system (NE flank of Mount Etna), from November 2006 to April 2007. The results obtained with the three methodologies are in a general agreement with each other and reflect the tectonic settings of the investigated study area. The lowest 222Rn values were recorded just on the fault plane, and relatively higher values were recorded a few tens of meters from the fault axis on both of its sides. This pattern could be explained as a dilution effect resulting from high rates of soil CO2 efflux. Time variations of 222Rn activity were mostly linked to atmospheric influences, whereas no significant correlation with the volcanic activity was observed. In order to further investigate regional radon distributions, spot measurements were made to identify sites having high Rn emissions that could subsequently be monitored for temporal radon variations.. SSNTD measurements allow for extended-duration monitoring of a relatively large number of sites, although with some loss of temporal resolution due to their long integration time. Continuous monitoring probes are optimal for detailed time monitoring, but because of their expense, they can best be used to complement the information acquired with SSNTD in a network of monitored sites.
    Description: In press
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.2. Tettonica attiva
    Description: 4.4. Scenari e mitigazione del rischio ambientale
    Description: 4.5. Degassamento naturale
    Description: JCR Journal
    Description: reserved
    Keywords: Soil Radon and Thoron activity ; soil CO2 efflux ; Pernicana fault system ; Mount Etna ; volcano-tectonic monitoring ; 03. Hydrosphere::03.04. Chemical and biological::03.04.07. Radioactivity and isotopes ; 03. Hydrosphere::03.04. Chemical and biological::03.04.08. Instruments and techniques ; 04. Solid Earth::04.01. Earth Interior::04.01.99. General or miscellaneous ; 04. Solid Earth::04.02. Exploration geophysics::04.02.01. Geochemical exploration ; 04. Solid Earth::04.02. Exploration geophysics::04.02.05. Downhole, radioactivity, remote sensing, and other methods ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.06. Rheology, friction, and structure of fault zones ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous ; 04. Solid Earth::04.07. Tectonophysics::04.07.99. General or miscellaneous ; 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::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
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  • 22
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    An exceptional case of endogenous lava dome growth (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: During an eruption at the Bocca Nuova, one of the summit craters of Mt. Etna, in October-November 1999 a part of the crater floor near its WNW rim was uplifted to form a dome-shaped feature that consisted of older lava and pyroclastics filling the crater. This endogenous dome grew rapidly over the crater rim, thus being perched precariously over the steep outer slope of the Bocca Nuova, and near-continuous collapse of its steep flanks generated swiftly moving pyroclastic avalanches over a period of several hours. These avalanches advanced at speeds of 10-20 m s-1 and extended up to 0.7 km from their source on top of lavas emplaced immediately before. Their deposits were subsequently covered by lava flows that issued from vents below the front of the dome and from the Bocca Nuova itself. Growth of the dome was caused by the vertical intrusion of magma in the marginal W part of the crater, which deformed and uplifted previously emplaced, still hot and plastically deformable eruptive products filling the crater. The resulting avalanches had all characteristics of pyroclastic flows spawned by collapse of unstable flanks of lava domes, but in this case the magma involved was of mafic (hawaiitic) composition and would have, under normal circumstances, produced fluid lava flows. The formation of the dome and the generation of the pyroclastic avalanches owe their occurrence to the rheological properties of the eruptive products filling the crater, which were transformed into the dome, and to the morphological configuration of the Bocca Nuova and its surroundings. The density contrast between successive erupted products may also have played a role. Although events of this type are to be considered exceptional at Etna, their recurrence might represent a serious hazard to visitors to the summit area.
    Description: Published
    Description: 115-128
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: JCR Journal
    Description: reserved
    Keywords: Mt. Etna ; Bocca Nuova ; endogenous lava dome ; pyroclastic avalanches ; magma ascent ; 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::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions ; 05. General::05.08. Risk::05.08.99. General or miscellaneous
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  • 23
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    Modeling the interplay of fO2 and fS2 along the FeS-silicate melt equilibrium (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: In this paper we will discuss a simplified thermodynamic description for the saturation of FeS, either liquid or solid, in magmatic melts. The Conjugated-Toop–Samis–Flood–Grjotheim model [Moretti R. and Ottonello G., 2005. Solubility and speciation of sulfur in silicate melts, the Conjugated-Toop–Samis–Flood–Grjotheim (CTSFG) model. Geochimica et Cosmochimica Acta, 69, 801–823] has furnished the theoretical reference frame, since it already accounts for the solubility of gaseous sulfur and the speciation and oxidation state of sulfur in silicate melts. We provide a new model to predict the saturation of magmatic silicate melts with an FeS phase that is internally consistent with these previous parameterizations. The derived model provides an effective sulfogeobarometer, which is superior with respect to previous models. For magmas rising from depth to surface, our appraisal of molar volumes of sulfur-bearing species in silicate melts allows us to model oxidation–reduction processes at different pressures, and sulfur concentrations for saturationwith either liquid or solid phases. In this respect, the nature of the oxygen fugacity buffer is critical. On the basis of model results on some typical compositions of volcanological interest, the sulfur contents at sulfide saturation (SCSS) have been calculated and the results duplicate the experimental observations that the SCSS is positively correlatedwith pressure forwatersaturated acidic melts and negatively correlated with pressure for water-poor basaltic melts. This new model provides fO2–fS2 pairs of FeS saturation of natural silicatemelts. In caseswhere the redox constraint is lacking, the model can be used to investigate whether the dissolved sulfur content approaches SCSS or not, and if so, to estimate at which fO2 value the silicate melt is saturated with a sulfide phase
    Description: Published
    Description: 286–298
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: Sulfur ; Silicate melt ; Iron sulfide ; Chemical thermodynamics ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 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
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  • 24
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    Emplacement mechanism of gravity flows inferred fromhigh resolution Lidar data: The 1944 Somma–Vesuvius lava flow (Italy) (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: A Digital Terrain Model derived from high resolution Lidar data allows the determination of the morphometric and physical parameters of a lava flow erupted from the Somma–Vesuvius volcano in 1944. The downstream variation of morphometric parameters including slope, aspect, relative relief, thickness, width, and cross sectional area is analyzed, and the changes in viscosity, velocity and flow rate are estimated. The aims of the analyses are to recognize different flow surfaces, to reconstruct the flow kinematics, and to obtain information on the mechanism of emplacement. The results indicate that the 1944 lava flow can be divided in three sectors: a near vent sector (NVS) characterized by a toe-like surface, an intermediate sector (IS) with an ‘a’ātype brittle surface, and a distal sector (DS) with a sheet-like ductile surface. Lateral leveés and channels do not occur in NVS, whereas they are well developed in IS. In DS, leveés increase with an increasing distance from the vent. Fold-like surfaces occur in NVS and DS, reflecting local shortening processes due to a decrease in the slope of the substratum and overflows from the main channel. IS and DS emplaced between March 18 and 21, 1944, whereas NVS emplaced on March 19 and partly covered IS. The morphometric and physical parameters indicate that IS moved in a ‘tube’-like regime, whereas DS emplaced in a 'mobile crust' regime. The IS to DS transition is marked by an increase in velocity and the flow rate, and by a decrease in thickness, width, cross sectional area, and viscosity. This transition is due to an abrupt increase in the slope of the substratum. The estimated velocity values are in good agreement with the measurements during the 1944 eruption. The analysis used here may be extended to other lava flows. Some gravity flows (debris/mud flows, floods, and avalanches) have rheological properties and shapes similar to those of lavas, and the same process-form relationships may apply to these flows. The approach used here may be therefore useful for evaluating hazards from various gravity currents.
    Description: Published
    Description: 223–235
    Description: 1.10. TTC - Telerilevamento
    Description: 3.6. Fisica del vulcanismo
    Description: 5.4. TTC - Sistema Informativo Territoriale
    Description: JCR Journal
    Description: reserved
    Keywords: Lava flow ; Gravity flow ; Lidar ; Digital Terrain Model (DTM) ; 04. Solid Earth::04.04. Geology::04.04.03. Geomorphology ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
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  • 25
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    Recicling and “re-hydration” of degassed magma inducing transient dissolution/crystallization events at Stromboli (Italy) (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Intrusive degassing and recycling of degassed and dense magma at depth have been proposed for a long time at Stromboli. The brief explosive event that occurred at the summit craters on 9 January 2005 threw out bombs and lapilli that could be good candidates to illustrate recycling of shallow degassed magma at depth. We present an extensive data set on both the textures and the mineral, bulk rock and glassy matrix chemistry of the “9 Jan” products. The latter have the common shoshonitic–basaltic bulk composition of lavas and scoriae issued from typical strombolian activity. In contrast they differ by the heterogeneous chemistry of their matrix glasses and their crystal textures that testify to crystal dissolution event(s) just prior magma crystallization upon ascent and eruption. Comparison between mineral paragenesis of the natural products and experimental phase equilibria suggest water-induced magma re-equilibration. We propose that mineral dissolution is related to water enrichment of the recycled degassed magma, via differential gas bubble transfer and to some extents its physical mixing with volatile-rich magma blobs. However, all these features illustrate transient processes. Even though evidence of mineral dissolution is ubiquitous at Stromboli, its effect on the bulk magma chemistry is minor because of the subtle interplay between mineral dissolution and crystallization in magmas having comparable bulk chemistry.
    Description: Published
    Description: 325-336
    Description: JCR Journal
    Description: reserved
    Keywords: mineral dissolution ; magma chemistry ; volatiles ; trace elements ; Stromboli ; 04. Solid Earth::04.04. Geology::04.04.05. Mineralogy and petrology ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 26
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    Seismotectonics of strike–slip earthquakes within the deep crust of southern Italy: Geometry, kinematics, stress field and crustal rheology of the Potenza 1990–1991 seismic sequences (Mmax 5.7) (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: We present a revision and a seismotectonic interpretation of deep crust strike–slip earthquake sequences that occurred in 1990– 1991 in the Southern Apennines (Potenza area). The revision is motivated by: i) the striking similarity to a seismic sequence that occurred in 2002 ∼140 km NNW, in an analogous tectonic context (Molise area), suggesting a common seismotectonic environment of regional importance; ii) the close proximity of such deep strike–slip seismicity with shallow extensional seismicity (Apennine area); and iii) the lack of knowledge about the mechanical properties of the crust that might justify the observed crustal seismicity. A comparison between the revised 1990–1991 earthquakes and the 2002 earthquakes, as well as the integration of seismological data with a rheological analysis offer new constraints on the regional seismotectonic context of crustal seismicity in the Southern Apennines. The seismological revision consists of a relocation of the aftershock sequences based on newly constrained velocity models. New focal mechanisms of the aftershocks are computed and the active state of stress is constrained via the use of a stress inversion technique. The relationships among the observed seismicity, the crustal structure of the Southern Apennines, and the rheological layering are analysed along a crustal section crossing southern Italy, by computing geotherms and two-mechanism (brittle frictional vs. ductile plastic strength) rheological profiles. The 1990–1991 seismicity is concentrated in a well-defined depth range (mostly between 15 and 23 km depths). This depth range corresponds to the upper pat of the middle crust underlying the Apulian sedimentary cover, in the footwall of the easternmost Apennine thrust system. The 3D distribution of the aftershocks, the fault kinematics, and the stress inversion indicate the activation of a right-lateral strike–slip fault striking N100°E under a stress field characterized by a sub-horizontal N142°-trending σ1 and a sub-horizontal N232°-trending σ3, very similar to the known stress field of the Gargano seismic zone in the Apulian foreland. The apparent anomalous depths of the earthquakes (N15 km) and the confinement within a relatively narrow depth range are explained by the crustal rheology, which consists of a strong brittle layer at mid crustal depths sandwiched between two plastic horizons. This articulated rheological stratification is typical of the central part of the Southern Apennine crust, where the Apulian crust is overthrusted by Apennine units. Both the Potenza 1990–1991 and the Molise 2002 seismic sequences can be interpreted to be due to crustal E–W fault zones within the Apulian crust inherited from previous tectonic phases and overthrusted by Apennine units during the Late Pliocene–Middle Pleistocene. The present strike–slip tectonic regime reactivated these fault zones and caused them to move with an uneven mechanical behaviour; brittle seismogenic faulting is confined to the strong brittle part of the middle crust. This strong brittle layer might also act as a stress guide able to laterally transmit the deviatoric stresses responsible for the strike–slip regime in the Apulian crust and may explain the close proximity (nearly overlapping) of the strike–slip and normal faulting regimes in the Southern Apennines. From a methodological point of view, it seems that rather simple two-mechanism rheological profiles, though affected by uncertainties, are still a useful tool for estimating the rheological properties and likely seismogenic behaviour of the crust.
    Description: Published
    Description: 281–300
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: reserved
    Keywords: Strike–slip seismicity; ; Deep crust; ; Active stress; ; Crustal rheology; ; Seismotectonics; ; Southern Apennines ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
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  • 27
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    The role of pre-existing thrust faults and topography on the styles of extension in the Gran Sasso range (central Italy) (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Structural analysis and field mapping together with simple geometrical and flexural elastic models, document that two styles of Quaternary extensional tectonics characterized the Gran Sasso range (central Apennines, Italy). In the western part of the range, extension took place on 10–15-km-long range-front normal faults with associated 600–1000-m-high escarpments showing evidence of Late Glacial–Holocene activity. This topography has been reproduced with a thin elastic plate subjected to the isostatic forces induced by the movement along high-angle (55°–65°) planar normal faults. In the eastern part of the belt extension occurred on shallow-dipping normal faults (30°–35°) which reactivated progressively deeper pre-existing thrusts. In this area antithetic "domino" faults formed to accommodate the mechanical adjustment of the hanging-wall over a variably dipping major fault surface. The eastward increase in shortening, due to the earlier compressional phase, documented in the Gran Sasso belt by previous authors, accounts for the more developed zones of weakness and high topographic relief in the eastern sector. This setting could explain the different styles of extension and the more advanced northeastern limit of normal faulting in the eastern sector. This work suggests that normal faults can originate either with low- or high-angle geometry in the upper crust according to the pre-existing tectonic setting and that topography could be important in controlling the geometry and pattern of migrating normal faulting.
    Description: Published
    Description: 229-254
    Description: JCR Journal
    Description: reserved
    Keywords: extensional tectonics ; Quaternary ; thrust faults ; topography ; Apennines ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
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  • 28
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    Dike propagation in volcanic edifices: Overview and possible developments (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Eruptions are often fed by dikes; therefore, better knowledge of dike propagation is necessary to improve our understanding of how magma is transferred and extruded at volcanoes. This study presents an overview of dike patterns and the factors controlling dike propagation within volcanic edifices. Largely based on published data, three main types of dikes (regional, circumferential and radial) are illustrated and discussed. Dike pattern data from 25 volcanic edifices in different settings are compared to derive semi-quantitative relationships between the topography (relief, shape, height, and presence of sector collapses) of the volcano, tectonic setting (presence of a regional stress field), and mean composition (SiO2 content). The overview demonstrates how dike propagation in a volcano is not a random process; rather, it depends from the following factors (listed in order of importance): the presence of relief, the shape of the edifice and regional tectonic control. We find that taller volcanoes develop longer radial dikes, whose (mainly lateral) propagation is independent of the composition of magma or the aspect ratio of the edifice. Future research, starting from these preliminary evaluations, should be devoted to identifying dike propagation paths and likely locations of vent formation at specific volcanoes, to better aid hazards assessment.
    Description: In press
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.2. Tettonica attiva
    Description: 3.5. Geologia e storia dei sistemi vulcanici
    Description: 3.6. Fisica del vulcanismo
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: open
    Keywords: dikes ; volcanoes ; topography ; tectonic setting ; eruptions ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.07. Tectonophysics::04.07.99. General or miscellaneous ; 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
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  • 29
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    Elemental and isotope covariation of noble gases in mineral phases from Etnean volcanics erupted during 2001–2005, and genetic relation with peripheral gas discharges (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: During 2001–2005, Mount Etna was characterized by intense eruptive activity involving the emission of petrologically different products from several vents, which involved at least two types of magma with different degrees of evolution. We investigated the ratios and abundances for noble-gas isotopes in fluid inclusions trapped in olivines and pyroxenes in the erupted products. We confirm that olivine has the most efficient crystalline structure for preserving the pristine composition of entrapped gases, while pyroxene can suffer diffusive He loss. Both the minerals also experience noble gas air contamination after eruption. Helium isotopes of the products genetically linked to the two different magmas fall in the isotopic range typical of the Etnean volcanism. This result is compatible with the metasomatic process that the Etnean mantle is undergoing by fluids from the Ionian slab during the last ten kyr, as previously inferred by isotope and trace element geochemistry. Significant differences were also observed among olivines of the same parental magma that erupted throughout 2001–2005, with 3He/4He ratios moving from about 7.0 Ra in 2001 volcanites, to 6.6 Ra in 2004–2005 products. Changes in He abundances and isotope ratios were attributed to variations in protracted degassing of the same magma bodies from the 2001 to the 2004–2005 events, with the latter lacking any contribution of undegassed magma. The decrease in 3He/4He is similar to that found from measurements carried out every fifteen days during the same period in gases discharged at the periphery of the volcano. To our knowledge this is the first time that such a comparison has been performed so in detail, and provides strong evidence of the real-time feeding of peripheral emissions by magmatic degassing.
    Description: Published
    Description: 683-690
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: JCR Journal
    Description: open
    Keywords: fluid inclusions ; noble gases ; helium isotopes ; magma degassing ; olivine ; pyroxene ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data
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  • 30
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    Shifting styles of basaltic explosive activity during the 2002-03 eruption of Mt. Etna, Italy (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The 2002–03 flank eruption of Etna was characterized by two months of explosive activity that produced copious ash fallout, constituting a major source of hazard and damage over all eastern Sicily. Most of the tephra were erupted from vents at 2750 and 2800 m elevation on the S flank of the volcano, where different eruptive styles alternated. The dominant style of explosive activity consisted of discrete to pulsing magma jets mounted by wide ash plumes, which we refer to as ash-rich jets and plumes. Similarly, ash-rich explosive activity was also briefly observed during the 2001 flank eruption of Etna, but is otherwise fairly uncommon in the recent history of Etna. Here, we describe the features of the 2002–03 explosive activity and compare it with the 2001 eruption in order to characterize ash-rich jets and plumes and their transition with other eruptive styles, including Strombolian and ash explosions, mainly through chemical, componentry and morphology investigations of erupted ash. Past models explain the transition between different styles of basaltic explosive activity only in terms of flow conditions of gas and liquid. Our findings suggest that the abundant presence of a solid phase (microlites) may also control vent degassing and consequent magma fragmentation and eruptive style. In fact, in contrast with the Strombolian or Hawaiian microlite-poor, fluidal, sideromelane clasts, ash-rich jets and plumes produce crystal-rich tachylite clasts with evidence of brittle fragmentation, suggesting that high groundmass crystallinity of the very top part of the magma column may reduce bubble movement while increasing fragmentation efficiency.
    Description: In press
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: Etna ; basaltic explosive activity ; ash-rich jet and plume ; tachylite ; sideromelane ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 31
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    The Tortonian salinity crisis in the Fortuna Basin (southeastern Spain): Stratigraphic record, tectonic scenario and chronostratigraphy (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The Neogene Fortuna and Bajo Segura basins are located on the northeastern end of the Trans-Alborán Shear Zone (TASZ), on the eastern Betic cordillera. The stratigraphic study of the infilling of these basins has shown two major sedimentary discontinuities. The first one, represented by an erosive surface separating open marine marls from an overlying coastal conglomeratic unit, is linked to the onset of the activity along the TASZ, which in this area indicates the beginning of the Abanilla Thrust emplacement. In the Fortuna Basin, the Tortonian salinity crisis, registered over this older first discontinuity, was therefore related to tectonic processes of the eastern portion of the cordillera and consequently would not have an expression in the western basins. The age of the Tortonian Salinity Crisis has been established with nannofossil biostratigraphy as Latest Tortonian at a somewhat lower stratigraphic position than previously recognized. The second sedimentary discontinuity was developed in relation with the known Mediterranean-wide Messinian salinity crisis.
    Description: Published
    Description: 474-481
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: reserved
    Keywords: Betic Cordillera ; Tortonian Salinity Crisis ; Messinian Salinity Crisis ; Trans-Alboran Shear Zone ; Fortuna Basin ; Spain ; 04. Solid Earth::04.04. Geology::04.04.10. Stratigraphy ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
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  • 32
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    Vertical-axis rotation of a foreland fold and implications for orogenic curvature: an example from the Southern Pyrenees, Spain (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: In curved orogenic systems where thrusting and vertical-axis rotations have been documented, it is possible to determine whether the curvature is secondary or progressive based on the timing between the two motions. The South-Central Unit of the Southern Pyrenees provides an opportunity to investigate relationships between thrusting, folding, and vertical-axis rotation because of unusual preservation of Tertiary synorogenic sedimentary strata. Paleomagnetic samples were collected from 51 sites in the upper Eocene-lower Oligocene continental synorogenic strata of the Oliana anticline, a foreland fold along the eastern margin of the South-Central Unit. Site-mean characteristic remanent magnetization directions were determined from 17 sites through thermal demagnetization and principal component analysis. In addition, 72 samples were collected from 39 stratigraphic levels spanning the Upper Eocene marine marls and treated with thermal and alternating field demagnetization techniques. Of these, 53 samples yielded demagnetization trajectories that further constrained the rotation. Comparison of the observed mean paleomagnetic direction from the Oliana anticline with the expected direction indicates a counterclockwise rotation (R ± ΔR) of 20.3° ± 10.9°. Based on the stratigraphic horizons recording the rotation, the age of the rotation is younger than ~34 Ma (after deposition of Unit 3). Data covering the Upper Eocene-Lower Oligocene time interval indicate a similar magnitude of rotation, suggesting that late stage emplacement of thrust sheets hinterlandward of the Oliana anticline controlled the rotation, with rotation accommodated along regionally extensive evaporites. The well-constrained timing relationships between thrusting and rotation and the regional and local transport directions, suggest that the South-Central Unit is a progressive curve that formed through distributed shortening.
    Description: Published
    Description: 435-449
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: reserved
    Keywords: Pyrenees ; Oliana anticline ; synorogenic strata ; paleomagnetism ; salients ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
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  • 33
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    Paleo-environmental and volcano-tectonic evolution of the southeastern £ank of Mt. Etna during the last 225 ka inferred from the volcanic succession of the ‘Timpe’, Acireale, Sicily (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The tectonic escarpments locally known as ‘Timpe’ cut a large sector of the eastern flank of Etna, and allow an ancient volcanic succession dating back to 225 ka to be exposed. Geological and volcanological investigations carried out on this succession have allowed us to recognize relevant angular unconformities and volcanic features which are the remnants of eruptive fissures, as well as important changes in the nature, composition and magmatic affinity of the exposed volcanics. In particular, the recognition in the lower part of the succession of important and unequivocal evidence of ancient eruptive fissures led us to propose a local origin for these volcanics and to revise previous interpretations which attributed their westward-dipping to the progressive tectonic tilting of strata. These elements led us to reinterpret the main features of the volcanic activity occurring since 250 ka BP and their relationship with tectonic structures active in the eastern flank of Etna. We propose a complex paleo-environmental and volcanotectonic evolution of the southeastern flank of Mt. Etna, in which the Timpe fault system played the role of the crustal structure that allowed the rise and eruption of magmas in the above considered time span.
    Description: Published
    Description: 289-306
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.5. Geologia e storia dei sistemi vulcanici
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: Mount Etna ; tectonics ; fisssure eruptions ; columnar basalt ; fault escarpment ; xenoliths ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.03. Geomorphology ; 04. Solid Earth::04.04. Geology::04.04.05. Mineralogy and petrology ; 04. Solid Earth::04.04. Geology::04.04.06. Rheology, friction, and structure of fault zones ; 04. Solid Earth::04.04. Geology::04.04.07. Rock geochemistry ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.04. Geology::04.04.10. Stratigraphy ; 04. Solid Earth::04.04. Geology::04.04.11. Instruments and techniques ; 04. Solid Earth::04.07. Tectonophysics::04.07.99. General or miscellaneous ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.04. Plate boundaries, motion, and tectonics ; 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
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  • 34
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    Link between major flank slip and 2002–2003 eruption at Mt. Etna (Italy) (2008)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: The 2002–2003 Etna eruption is studied through earthquake distributions and surface fracturing. In September 2002, earthquake-induced surface rupture (sinistral offset 0.48 m) occurred along the E-W striking Pernicana Fault (PF), on the NE flank. In late October, a flank eruption accompanied further ( 0.77 m) surface rupturing, reaching a total sinistral offset of 1.25 m; the deformation then propagated for 18 km eastwards to the coastline (sinistral offset 0.03 m) and southwards, along the NW-SE striking Timpe (dextral offset 0.04 m) and, later, Trecastagni faults (dextral offset 0.035 m). Seismicity (〈4 km bsl) on the E flank accompanied surface fracturing: fault plane solutions indicate an overall ESEWNWextension direction, consistent with ESE slip of the E flank also revealed by ground fractures. A three-stage model of flank slip is proposed: inception (September earthquake), climax (accelerated slip and eruption) and propagation (E and S migration of the deformation).
    Description: Published
    Description: 2286
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.2. Tettonica attiva
    Description: 3.5. Geologia e storia dei sistemi vulcanici
    Description: 3.6. Fisica del vulcanismo
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: reserved
    Keywords: volcano seismology ; surface fracturing ; flank slip ; eruption ; Etna ; 04. Solid Earth::04.01. Earth Interior::04.01.99. General or miscellaneous ; 04. Solid Earth::04.01. Earth Interior::04.01.02. Geological and geophysical evidences of deep processes ; 04. Solid Earth::04.02. Exploration geophysics::04.02.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous ; 04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution ; 04. Solid Earth::04.06. Seismology::04.06.02. Earthquake interactions and probability ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk ; 04. Solid Earth::04.07. Tectonophysics::04.07.99. General or miscellaneous ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
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  • 35
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    The Database of Individual Seismogenic Sources (DISS), version 3: summarizing 20 years of research on Italy’s earthquake geology (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: This paper describes the main characteristics, the evolution, and the structure of the Database of Individual Seismogenic Sources (DISS) and particularly of its release of early 2007. The Database contains the results of the investigations of the active tectonics in Italy during the past 20 years. The first two sections of this paper document the recent evolution in mapping and archiving Italian active fault data in relation to important achievements in the understanding of Italian tectonics, some of which were spurred by significant earthquakes. The central sections describe the current structure of the Database, the reasons for its assumptions and data categories, its current contents, its evolution through several years of improvements. The last section describes how the current contents of the Database correspond with the existing strain and stress data available from focal mechanism, borehole breakout, and GPS data for the whole of Italy. The Database supplies a fresh and unified view of active and seismogenic processes in Italy by building on basic physical constraints concerning rates of crustal deformation, on the continuity of deformation belts and on the spatial relationships between adjacent faults, both at the surface and at depth.
    Description: INGVDPC grant to R. Basili (Project S2, Research Unit 1.1).
    Description: Published
    Description: 20-43
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: reserved
    Keywords: Earthquake geology ; Active fault ; Active tectonics ; Seismic source ; Seismic hazard ; 04. Solid Earth::04.06. Seismology::04.06.05. Historical seismology ; 04. Solid Earth::04.07. Tectonophysics::04.07.04. Plate boundaries, motion, and tectonics ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
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  • 36
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    The 2007 eruption of Stromboli volcano: Insights from real-time measurement of the volcanic gas plume CO2/SO2 ratio (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The recent eruption of Stromboli in February–April 2007 offered a unique chance to test our current understanding of processes driving the transition from ordinary (persistent Strombolian) to effusive activity, and the ability of instrumental geophysical and geochemical networks to interpret and predict these events. Here, we report on the results of two years of in-situ sensing of the CO2/SO2 ratio in Stromboli's volcanic gas plume, in the attempt to put constraints on the trigger mechanisms and dynamics of the eruption. We show that large variations of the plume CO2/SO2 ratio (range, 0.9–26) preceded the onset of the eruption (since December 2007), interrupting a period of relatively-steady and low ratios (time-averaged ratio, 4.3) lasting from at least May to November 2006. By contrasting our observations with numerical simulations of volcanic degassing at Stromboli, derived by use of an equilibrium saturation model, we suggest that the pre-eruptive increase of the ratio reflected an enhanced supply of deeply-derived CO2-rich gas bubbles to the shallowplumbing system. This larger-than-normal ascent of gas bubbles was likely sourced by a 1–3 km deep gas– melt separation region (probably a magma storage zone), and caused faster convective overturning of magmas in the shallow conduit; an increase in the explosive rate and in seismic tremor, and finally the collapse of the la Sciara del Fuoco sector triggering the effusive phase. The high CO2/SO2 ratios (up to 21) observed during the effusive phase, and particularly in the days and hours before a paroxysmal explosion on March 15, 2007, indicate the persistence of the same gas source; and suggest that de-pressurization of the same 1–3 km deep magma storage zone could have been the trigger mechanism for the paroxysm itself
    Description: In press
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: 2.4. TTC - Laboratori di geochimica dei fluidi
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: Stromboli ; plume chemistry ; magma degassing ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 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::04.08.06. Volcano monitoring
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  • 37
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    Miocene-Quaternary structural evolution of the Uyuni-Atacama region, Andes of Chile and Bolivia (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: We describe the Miocene-Quaternary geological-structural evolution of the region between the Salar de Uyuni and de Atacama, Andes of Chile and Bolivia. We recognised four main tectonic events based on fold geometry, fault kinematics and stratigraphic data. The oldest event, of Miocene age, is characterized by folding and reverse faulting of the sedimentary successions with an E-W direction of shortening in the northern part of the studied area and a WNW-ESE shortening in the southern part. The following two events, of Pliocene age, are characterized by lower shortening amounts; they occurred first by reverse faulting with a NW-SE-trending greatest principal stress (1, computed with striated fault planes) and a vertical least principal stress (3), followed by pervasive strike-slip faulting with the same NW-SE-trending 1 and a horizontal NE-SW 3. The fourth event, dating to the late Pliocene-Quaternary is characterised by normal faulting: the 3 still trends NE-SW, whereas the intermediate principal stress 2 exchanged with 1. Volcanism accompanied both the contractional, transcurrent and extensional tectonic phases. The Mio-Pliocene compression appears directly linked to a rapid convergence and an apparently important coupling between the continental and oceanic plates. The E-W to WNW-ESE direction of shortening of the Miocene structures and the NW-SE 1 of the Pliocene structures seem to be more linked to an intra-Andean re-orientation of structures following the WNW-directed absolute motion of the South-American Plate. The extensional deformations can be interpreted as related to gravity forces affecting the highest parts of the volcanic belt in a sort of asymmetrical (SW-ward) collapse of the belt.
    Description: In press
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: reserved
    Keywords: Chile ; Bolivia ; Andes ; tectonic phases ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
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  • 38
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    Seismic strain and seismogenic stress regimes in the crust of the southern Tyrrhenian region (2008)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: An investigation has been performed to identify and characterize the seismic deformation zones active over the last decades in the region of Italy that has experienced the strongest seismicity during the last centuries. The study is based on the estimate of hypocenter locations, fault plane solutions, seismogenic stress and seismic strain tensor orientations carried out using the entire dataset of the national and local seismic networks, and the recently improved three-dimensional (3D) crustal velocity model of the study area. A series of simulation tests have been performed to evaluate the significance of the earthquake space distribution obtained and whether it was influenced by network geometry problems related to the sea and the lack of ocean bottom seismometers. In the sectors where hypocentral location was synthetically proved to be reliable, space distributions of earthquakes located with epicenter and focal depth errors less than 3 and 4 km, respectively, have been compared with local geology in order to identify seismogenic faults. The dataset of 32 fault plane solutions estimated with fault parameter errors less than 20° has been used to investigate space variations of seismogenic stress and seismic strain orientations over the study area. Stress was found to be uniform in the Messina Strait and southern Calabria where inversion of the available set of 11 fault plane solutions showed clear evidence of an extensional regime. The different orientations of the minimum compressive stress and strain found in this sector, together with the information available on local geology and tectonics, lead us to propose that the seismicity occurring over the last decades in the Messina Strait and southern Calabria was not in general produced at the main faults, but at minor faults activated by the main tectonic stress field acting in the area. To the west, in the sector including western Etna, the Nebrodi chain and the western Aeolian Islands, analysis of the available set of 16 fault plane solutions revealed a certain degree of stress heterogeneity with an apparent prevalence of north–south compression. This east to west change of stress–strain regimes is evaluated in the light of current hypotheses regarding the geodynamics of the study region.
    Description: Published
    Description: 97-112
    Description: JCR Journal
    Description: open
    Keywords: crustal seismicity ; seismic strain ; seismogenic stress ; Tyrrhenian sea and Italy ; 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 05. General::05.02. Data dissemination::05.02.02. Seismological data
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  • 39
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    Neogene–Quaternary evolution of the central Apennine orogenic system (Italy): a structural and palaeomagnetic approach in the Molise region (2008)
    Elsevier
    Details
    Publication Date: 2022-05-30
    Description: We report on new palaeomagnetic and magnetic fabric analyses of mainly Upper Miocene sedimentary sequences from the external central Apennine fold and thrust belt (Molise area), where the principal compressive structures are clearly non-coaxial. The sampling was carried out on the E–W-oriented Matese–Frosolone thrust sheet, that for its geographical position and structural setting (superposition of thrusting, strike-slip and extensional tectonics since Late Miocene to present-day) represents a key structure for the comprehension of the Neogene–Quaternary evolution of the entire Molise area. Palaeomagnetic results suggest that the Matese–Frosolone thrust sheet counterclockwise rotated at least 35° after Messinian times. These data confirm that the present-day trend variability observed in the main compressional structures in the Apennine chain can be related to rotations about vertical axes rather than to changes in the stress field orientation, at least since Late Miocene times. Magnetic fabric analyses indicate that the studied sediments were subjected to very mild deformation, suggesting that the surface emergence of the thrust front of the Matese–Frosolone unit is located farther north, far from the studied area. Well-defined magnetic lineations of tectonic origin were only observed in sites close to localised belts of strike-slip deformation.
    Description: Published
    Description: 143-157
    Description: JCR Journal
    Description: reserved
    Keywords: Apennines ; palaeomagnetism ; anisotropy of magnetic susceptibility ; structural geology ; Neogene ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
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  • 40
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    Late Pliocene-Quaternary evolution of outermost hinterland basins of the Northern Apennines (Italy), and their relevance to active tectonics (2008)
    Elsevier
    Details
    Publication Date: 2022-08-25
    Description: We examine the tectonic evolution and structural characteristics of the Quaternary intermontane Mugello, Casentino, and Sansepolcro basins, in the Northern Apennines fold-andthrust belt. These basins have been classically interpreted to have developed under an extensional regime, and to mark the extension-compression transition. The results of our study have instead allowed framing the formation of these basins into a compressive setting tied to the activity of backthrust faults at their northeastern margin. Syndepositional activity of these structures is manifested by consistent architecture of sediments and outcrop-scale deformation. After this phase, the Mugello and Sansepolcro basins experienced a phase of normal faulting extending from the middle Pleistocene until Present. Basin evolution can be thus basically framed into a two-phase history, with extensional tectonics superposed onto compressional structures. Analysis of morphologic features has revealed the occurrence of fresh fault scarps and interaction of faulting with drainage systems, which have been interpreted as evidence for potential ongoing activity of normal faults. Extensional tectonics is also manifested by recent seismicity, and likely caused the strong historical earthquakes affecting the Mugello and Sansepolcro basins. Qualitative comparison of surface information with depth-converted seismic data suggests the basins to represent discrete subsiding areas within the seismic belt extending along the axial zone of the Apennines. The inferred chronology of deformation and the timing of activity of normal faults have an obvious impact on the elaboration of seismic hazard models.
    Description: Published
    Description: 336-356
    Description: 2T. Deformazione crostale attiva
    Description: JCR Journal
    Description: open
    Keywords: Northern Apennines ; Basin evolution ; structural analysis ; active tectonics ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
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  • 41
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    An expanded non-Arrhenian model for silicate melt viscosity: A treatment for metaluminous, peraluminous and peralkaline liquids (2007)
    Elsevier
    Details
    Publication Date: 2020-10-29
    Description: We present new viscosity measurements for melts spanning a wide range of anhydrous compositions including: rhyolite, trachyte, moldavite, andesite, latite, pantellerite, basalt and basanite. Micropenetration and concentric cylinder viscometry measurements cover a viscosity range of 10−1 to 1012 Pas and a temperature range from 700 to 1650 °C. These new measurements, combined with other published data, provide a high-quality database comprising ∼800 experimental data on 44 well-characterized melt compositions. This database is used to recalibrate the model proposed by Giordano and Dingwell [Giordano, D., Dingwell, D. B., 2003a. Non-Arrhenian multicomponent melt viscosity: a model. Earth Planet. Sci. Lett. 208, 337–349] for predicting the viscosity of natural silicate melts. The present contribution clearly shows that: (1) the viscosity (η)–temperature relationship of natural silicate liquids is very well represented by the VFT equation [log η=A+B/ (T−C)] over the full range of viscosity considered here, (2) the use of a constant high-T limiting value of melt viscosity (e.g., A) is fully consistent with the experimental data, (3) there are 3 different compositional suites (peralkaline, metaluminous and peraluminous) that exhibit different patterns in viscosity, (4) the viscosity of metaluminous liquids is well described by a simple mathematical expression involving the compositional parameter (SM) but the compositional dependence of viscosity for peralkaline and peraluminous melts is not fully controlled by SM. For these extreme compositions we refitted the model using a temperature-dependent parameter based on the excess of alkalies relative to alumina (e.g., AE/SM). The recalibrated model reproduces the entire database to within 5% relative error (e.g., RMSE of 0.45 logunits).
    Description: Published
    Description: 42–56
    Description: reserved
    Keywords: Viscosity ; Model ; Silicate melts ; Metaluminous ; Peraluminous ; Peralkaline ; 04. Solid Earth::04.01. Earth Interior::04.01.05. Rheology ; 04. Solid Earth::04.04. Geology::04.04.05. Mineralogy and petrology ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
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  • 42
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    The effect of H2O on the viscosity of K-trachytic melts at magmatic temperatures (2007)
    Elsevier
    Details
    Publication Date: 2020-10-29
    Description: Viscosity of hydrous trachytes from the Agnano Monte Spina eruption (Phlegrean Fields, Italy) has been determined at 1.0 GPa and temperatures between 1200 and 1400 °C using the falling sphere method in a piston cylinder apparatus. The H2O content in the melts ranged from 0.18 to 5.81 wt.%. These high-temperature hydrous viscosities, along with previous ones determined at low-temperature (anhydrous and hydrous) and at high-temperature (anhydrous), at 1 atm on the same melt composition, represent the only complete viscosity data set available for K-trachyticmelts, frommagmatic to volcanic conditions.Viscosity decreases with increasing temperature andwater content in the melt.At constant temperature, viscosity appears to significantly decreasewhen the first wt.% ofH2Ois added.At H2O content higher than 3 wt.% the effect of temperature on viscosity is slight. Moreover, the deviation from Arrhenian behaviour towards greater “fragility” occurs with increasing water content. We combined low- and high-temperature viscosities (also from literature) and parameterized themby the use of a modified Vogel–Fulcher–Tamman equation, which accommodates the non-Arrhenian temperature dependence ofmelt viscosity.Moreover, in order to explore the extent to which the improved knowledge of Agnano Monte Spina trachyte viscosity may affect simulation of volcanic eruption at Phlegrean Fields, we included our viscosity models in numerical simulations of magma flow and fragmentation along volcanic conduits. These simulations show that the new parameterizations (and hence the new equations) give stronger predictions in the temperature interval relevant for magmatic and eruptive processes.
    Description: Published
    Description: 124-137
    Description: JCR Journal
    Description: reserved
    Keywords: Viscosity ; Trachyte ; Falling sphere method ; Vogel–Fulcher–Tamman equation ; 04. Solid Earth::04.08. Volcanology::04.08.02. Experimental volcanism ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
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  • 43
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    Non-Newtonian rheology of crystal-bearing magmas and implications for magma ascent dynamics (2007)
    Elsevier
    Details
    Publication Date: 2021-01-27
    Description: The eruptive dynamics of volcanic systems are largely controlled by the viscosity of deforming magma. Here we report the results of a series of high-temperature, high-pressure experiments at conditions relevant for volcanic conduits (250 MPa confining pressure and temperature between 500 °C and 900 °C) that were undertaken to investigate the rheology of magma with crystal fractions varying between 0.5 and 0.8 (50 to 80 wt.%) at different strain-rate conditions. The experiments demonstrate that the presence of crystals increases the relative viscosity (ratio between the viscosity of the mixture and the viscosity of the melt phase) of magmas and additionally induces a decrease of the relative viscosity with increasing strain-rate (shear thinning, non-Newtonian behavior). The experimental results, combined with existing data at low crystal fractions (0–0.3), were used to develop a semi-empirical parameterization that describes the variations of relative viscosity for crystal fractions between 0 and 0.8 and accounts for the complex non-Newtonian rheology of crystal-bearing magmas. The new parameterization, included into numerical models simulating the magma ascent dynamics, reveals that strain-rate-dependent rheology significantly modifies the dynamic behavior inside volcanic conduits, particularly affecting the magma fragmentation conditions.
    Description: Published
    Description: 402-419
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: partially_open
    Keywords: magma rheology ; experimental deformation ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
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  • 44
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    High-temperature viscosity measurements of hydrous albite liquid using in-situ falling sphere viscometry at 2.5 GPa (2007)
    Elsevier
    Details
    Publication Date: 2020-10-29
    Description: In-situ falling-sphere viscometry using shadow radiography in a multianvil apparatus was conducted on a series of samples along the NaAlSi3O8–H2O join up to 2.8 wt.% H2O at the Spring-8 synchrotron radiation facility (Hyogo, Japan). This allowed us to determine viscosities normally too low to be measured at ambient pressure for hydrous silicate melts at high temperatures due to rapid devolatilization. Pressure was fixed at 2.5 GPa for all experiments allowing us to gauge the effect of chemical composition on viscosity. In particular, the series of samples allowed us to vary the melt's degree of polymerization while maintaining a constant Al to Si ratio. Our results show that, for all samples, viscosity decreases as a function of pressure between 1 atm and 2.5 GPa at 1550 °C, indicating that the pressure anomaly can still be observed as depolymerization of the melt increases from nominally 0 (dry albite liquid) to NBO/T=0.8 (assuming water speciation entirely as hydroxyl groups at experimental conditions). We also find that the magnitude of the decrease in viscosity over this pressure interval does not appear to be dependent on the amount of water in the melt (i.e., NBO/T). An explanation for this behavior might be that the molar volume, at least over this limited compositional range, is nearly constant and the effects of compression of these melts, though different in degree of polymerization, are similar.
    Description: Published
    Description: 2-9
    Description: JCR Journal
    Description: reserved
    Keywords: Viscosity ; Silicate melts ; High pressure ; 04. Solid Earth::04.01. Earth Interior::04.01.05. Rheology ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
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  • 45
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    Crustal contamination and crystal entrapment during polybaric magma evolution at Mt.Somma-Vesuvius volcano, Italy: Geochemical and Sr isotope evidence (2007)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: New major and trace element analyses and Sr-isotope determinations of rocks from Mt. Somma–Vesuvius volcano produced from 25 ky BP to 1944 AD are part of an extensive database documenting the geochemical evolution of this classic region. Volcanic rocks include silica undersaturated, potassic and ultrapotassic lavas and tephras characterized by variable mineralogy and different crystal abundance, as well as by wide ranges of trace element contents and a wide span of initial Sr-isotopic compositions. Both the degree of undersaturation in silica and the crystal content increase through time, being higher in rocks produced after the eruption at 472 AD (Pollena eruption). Compositional variations have been generally thought to reflect contributions from diverse types of mantle and crust. Magma mixing is commonly invoked as a fundamental process affecting the magmas, in addition to crystal fractionation. Our assessment of geochemical and Srisotopic data indicates that compositional variability also reflects the influence of crustal contamination during magma evolution during upward migration to shallow crustal levels and/or by entrapment of crystal mush generated during previous magma storage in the crust. Using a variant of the assimilation fractional crystallization model (Energy Conservation– Assimilation Fractional Crystallization; [Spera and Bohrson, 2001. Energy-constrained open-system magmatic processes I: General model and energy-constrained assimilation and fractional crystallization (EC–AFC) formulation. J. Petrol. 999– 1018]; [Bohrson, W.A. and Spera, F.J., 2001. Energy-constrained open-system magmatic process II: application of energyconstrained assimilation–fractional crystallization (EC–AFC) model to magmatic systems. J. Petrol. 1019–1041]) we estimated the contributions from the crust and suggest that contamination by carbonate rocks that underlie the volcano (2 km down to 9–10 km) is a fundamental process controlling magma compositions at Mt. Somma–Vesuvius in the last 8 ky BP. Contamination in the mid- to upper crust occurred repeatedly, after the magma chamber waxed with influx of new mantle- and crustal-derived magmas and fluids, and waned as a result of magma withdrawal and production of large and energetic plinian and subplinian eruptions.
    Description: Published
    Description: 303– 329
    Description: reserved
    Keywords: Mt. Somma–Vesuvius volcano ; Sr isotopes ; Geochemistry ; Crustal contamination ; Mantle source ; Phenocryst entrapment ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data
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  • 46
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    Unveiling the Sources of the Catastrophic 1456 Multiple Earthquake: Hints to an Unexplored Tectonic Mechanism in Southern Italy (2007)
    Seismological Society of America
    Details
    Publication Date: 2017-04-04
    Description: We revisited data related to the 1456 seismic crisis, the largest earthquake to have ever occurred in peninsular Italy, in search of its causative source(s). Data about this earthquake consist solely of historical reports and their intensity assessment. Because of the age of this multiple earthquake, the scarcity and sparseness of the data, and the unusually large damage area, no previous studies have attempted to attribute the 1456 events to specific faults. Existing analytical methods to identify a likely source from intensity data also proved inappropriate for such a sparse dataset, since historical evidence suggests that the cumulative damage pattern contains at least three widely separated events. We subdivided the 1456 damage pattern into three independent mesoseismal areas; each of these areas falls onto east–west tectonic trends previously identified and marked by deep (〉10 km) right-lateral slip earthquakes. Based on this evidence we propose (1) that the 1456 events were generated by individual segments of regional east–west structures and are evidence of a seismogenic style that involves oblique dextral reactivation of east–west lower crustal faults; (2) that each event may have triggered subsequent but relatively distant events in a cascade fashion, as suggested by historical accounts; hence (3) that the 1456 sequence reveals a fundamental but unexplored mechanism of tectonic deformation and seismic release in southern Italy. This style dominates the region that lies between the northwest–southeast system of large extensional faults straddling the crest of the southern Apennines and the buried outer front of the chain. Although the quality of the available information concerning the 1456 earthquake is naturally limited, we show that the overlap of the damage distribution, the orientation and characteristics of regional tectonic structures, the seismicity patterns, and the focal mechanisms all concur with our interpretations and would be difficult to justify otherwise.
    Description: Published
    Description: 725-748
    Description: JCR Journal
    Description: open
    Keywords: historical seismicity ; macroseismic data ; seismogenic faults ; southern Italy ; 04. Solid Earth::04.06. Seismology::04.06.05. Historical seismology ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
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  • 47
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    Changing conditions of magma ascent and fragmentation during the Etna 122 BC basaltic Plinian eruption: Evidence from clast microtextures (2007)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The Etna 122 BC basaltic eruption had two Plinian phases, each preceded and followed by weak phreatic and phreatomagmatic activity. This study infers changing eruption dynamics from density, grain size, and microtextural data from the erupted pyroclasts. The Plinian clasts show no evidence for quenching by external water; instead, all clasts are microvesicular and have high bubble number densities relative to the products of weaker basaltic explosive eruptions, suggesting that the 122 BC magma underwent coupled degassing linked to rapid ascent and decompression. This coupled degassing was probably enhanced by crystallization of abundant microlites, which increased the magma's effective viscosity during conduit ascent. Detailed measurements of vesicles and microlites show wide variations in number densities, size distributions, and shapes among clasts collected over narrow stratigraphic intervals. For such a diversity of clasts to be expelled together, portions of melt with contrasting ascent and degassing histories must have arrived at the fragmentation surface at essentially the same time. We suggest that a parabolic velocity profile across the conduit ensured that magma near the conduit walls ascended more slowly than magma along the axis, leading to a longer residence time and more advanced degrees of outgassing and crystallization in the marginal magma. In our model, accumulation of this outgassed, viscous magma along conduit walls reduced the effective radius of the shallow conduit and led to blockages that ended the Plinian phases.
    Description: Published
    Description: 333-354
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: basaltic Plinian ; Etna ; vesicles ; microlites ; conduit dynamics ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
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  • 48
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    Control of magma flow in dykes on cyclic lava dome extrusion (2007)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: Lava dome eruptions are commonly characterized by large fluctuations in discharge rate with cyclic behaviour on time-scales ranging from hours to decades. Examples include Bezymianny volcano (Russia), Merapi (Java), Santiaguito (Guatemala), Mt St Helens (USA), Mt Unzen (Japan), and Soufrie`re Hills volcano (Montserrat). Previous models have assumed simple cylindrical conduits for magma transport, but extrusions are mainly fed by dykes, with cylindrical geometries developing only at shallow levels. The widths of dykes embedded in an elastic medium are influenced by local magma pressure, affecting flow rates and system dynamics strongly. We develop a model for magma flow in dykes, which predicts intense pulsations of magma extrusion for the case of a constant source pressure. The period time scale is determined by the elastic deformation of the dyke walls and the length-to-width ratio of the dyke. The dyke acts like a volumetric capacitor, storing magma as pressure increases and then releasing magma in a pulse of extrusion. For the Soufrie`re Hills volcano, cyclic extrusions with time-scales of a few weeks are predicted for dykes 300–500 m long and 3–6 m wide, matching observations. The model explains the sharp onset of tilt pulsations and seismic swarms.
    Description: Published
    Description: L02303
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: Control ; magma flow ; dykes ; cyclic lava ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.04. Thermodynamics
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  • 49
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    Halogen diffusion in a basaltic melt (2007)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The diffusion of the halogens fluorine, chlorine, and bromine was measured in a hawaiitic melt from Mt. Etna at 500 MPa and 1.0 GPa, 1250 to 1450 ºC at anhydrous conditions; the diffusion of F and Cl in the melt was also studied with about 3 wt% of dissolved water. Experiments were performed using the diffusion-couple technique in a piston cylinder. Most experiments were performed with only one halogen diffusing between the halogen-enriched and halogen-poor halves of the diffusion couple, but a few experiments with a mixture of halogens (F, Cl, Br) were also performed in order to investigate the possibility of interactions between the halogens during diffusion. Fluorine and chlorine diffusivity show a very similar behavior, slightly diverging at low temperature. Bromine diffusion is a factor of about 2 to 5 lower than the other halogens in this study. Diffusion coefficients for fluorine range between 2.3x10−11 and 1.4x10−10 m2s−1, for chlorine between 1.1x10−11 and 1.3x10−10 and for bromine between 9.4x10−12 and 6.8x10−11 m2s−1. No pressure effect was detected at the conditions investigated. In experiments involving mixed halogens, the diffusivities appear to decrease slightly (by a factor of ~ 3), and are more uniform among the three elements. However, activation energies for diffusion do not appear to differ between experiments with individual halogens or when they are all mixed together. The effect of water increases the diffusion coefficients of F and Cl by no more than a factor of 3 compared to the anhydrous melt (DF = 4.0x10−11 to 1.6x10−10 m2s−1; DCl = 3.0x10−11 to 1.9x10−10 m2s−1). Comparing our results to the diffusion coefficients of other volatiles in nominally dry basaltic melts, halogen diffusivities are about one order of magnitude lower than H2O, similar to CO2, and a factor of ~5 higher than S. The contrasting volatile diffusivities may affect the variable extent of volatile degassing upon melt depressurization and vesiculation, and can help our understanding of the compositions of rapidly grown magmatic bubbles.
    Description: NSERC Discovery grant INGV-DPC 2004-2006 Projects (V3_6 – Etna)
    Description: Published
    Description: 3570-3580
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: JCR Journal
    Description: reserved
    Keywords: Diffusion ; Halogens ; Basalt ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
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  • 50
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    The Magma feeding system of Somma-Vesuvius (Italy)strato-volcano:new inferences from a review of geochemical and Sr,Nd,Pb and O isotope data. Volcanism in the Campania Plain: Vesuvius, Campi Flegrei and Ignimbrites (2007)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: A large database of major, trace and isotope (Sr, Nd, Pb, O) data exists for rocks produced by the volcanic activity of Somma-Vesuvius volcano. Variation diagrams strongly suggest a major role for evolutionary processes such as fractional crystallization, contamination, crystal trapping and magma mixing, occurring after magma genesis in the mantle. Most mafic magmas are enriched in LILE (K, Rb, Ba), REE (Ce, Sm) and Y, show small Nb–Ta negative anomalies, and have values of Nb/Zr at about 0.15. Enrichments in LILE, REE, Nb and Ta do not correlate with Sr isotope values or degree of both K enrichment and silica undersaturation. The results indicate mantle source heterogeneity produced by slab-derived components beneath the volcano. However, the Sr isotope values of Somma-Vesuvius increase from 0.7071 up to 0.7081 with transport through the uppermost 11–12 km of the crust. The Sr isotope variation suggests that the crustal component affected the magmas during ascent through the lithosphere to the surface. Our new geochemical assessment based on chemical, isotopic and fluid inclusion data points to the existence of three main levels of magma storage. Two of the levels are deep and may represent long-lived reservoirs, and an uppermost crustal level that probably coincides with the volcanic conduit. The deeper level of magma storage is deeper than 12 km and fed the 1944 AD eruption. The intermediate level coincides with the seismic discontinuity detected by Zollo et al. (1996) at about 8 km. This intermediate level supplies magmas with 87Sr/86Sr values between 0.7071 and 0.7074, and δO18 8‰ that typically erupted both during interplinian (i.e. 1906 AD) and sub-plinian (472 AD, 1631 AD) events. The shallowest level of magma storage at about 5 km was the site of magma chambers for the Pompei and Avellino eruptions. New investigations are necessary to verify the proposed magma feeding system.
    Description: Published
    Description: 183-204
    Description: open
    Keywords: NONE ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data
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  • 51
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    Time-dependent geochemistry of clinopyroxene from Alban Hills (Central Italy): clues to source and evolution of ultrapotassic magmas. (2007)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: We investigated chemical and isotopic compositions of clinopyroxene crystals from well age-constrained juvenile scoria clasts, lava flows, and hypoabyssal magmatic ejecta representative of the whole eruptive history of the Alban Hills Volcanic District. The Alban Hills is a Quaternary ultra-potassic district that was emplaced into thick limestone units along the Tyrrhenian margin of Italy. Alban Hills volcanic products, even the most differentiated, are characterised by low SiO2 content. We suggest that the low silica activity in evolving magmas can be ultimately due to a decarbonation process occurring at the magma/limestone interface. According to the liquid line of descent we propose, the differentiation process is driven by crystallisation of clinopyroxene+leuciteFapatiteFmagnetite coupled with assimilation of a small amount of calcite and/or with interaction with crustal CO2. By combining age, chemical data, strontium and oxygen isotopic compositions, and REE content of clinopyroxene, we give insights into the evolution of primitive ultrapotassic magmas of the Alban Hills Volcanic District over an elapsed period of about 600 kyr. Geochemical features of clinopyroxene crystals, consistent with data coming from other Italian ultrapotassic magmas, indicate that Alban Hills primary magmas were generated from a metasomatized lithospheric mantle source. In addition, our study shows that the 87Sr / 86Sr and LREE/HREE of Alban Hills magmas continuously diminished during the 600–35 ka time interval of the Alban Hills eruptive history, possibly reflecting the progressive depletion of the metasomatized mantle source of magmas.
    Description: Published
    Description: 330–346
    Description: JCR Journal
    Description: reserved
    Keywords: Clinopyroxene ; 87Sr / 86Sr ; REE ; Ultrapotassic rocks ; Alban Hills ; 04. Solid Earth::04.01. Earth Interior::04.01.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
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  • 52
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    Mapping the Moho of the Western Alps by wide-angle reflection seismics (2007)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: In the text
    Description: Published
    Description: 193-202
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: reserved
    Keywords: CROP ; wide-angle ; reflection ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
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  • 53
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    Magma-carbonate interaction: an experimental study on ultrapotassic rocks (2007)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The Alban Hills ultrapotassic volcanic district is one of the main districts emplaced during Quaternary time along the Tyrrhenian margin of Italy. Alban Hills lava flows and scoria clasts are made up essentially of clinopyroxenes and leucites and their chemical composition is mostly K-foiditic. Differentiated products (MgO〈3 wt%) are characterized by low SiO2 concentration (〈50 wt%) and geochemical features indicate that this unique differentiation trend is driven by crystal fractionation plus carbonate crust interaction. Notably, the Alban Hills Volcanic District was emplaced into thick limestone units. With the aim of constraining the magmatic differentiation, we performed experiments on the Alban Hills parental composition (plagioclase-free phono-tephrite) under anhydrous, hydrous, and hydrous-carbonated conditions. Experiments were carried out at 1 atm, 0.5 GPa and 1 GPa, temperatures ranging from 1050 to 1300 °C, and H2O and CaCO3 in the starting material up to 2 and 7 wt%, respectively. The experiments performed at 0.5 GPa resulted to be the most representative of the Alban Hills plumbing system. Clinopyroxene and leucite are the main phases occurring under all the investigated conditions and the liquidus phases. Nevertheless, our experimental results demonstrate that the occurrence of CaCO3 in the starting material strongly affects phase relations. Experiments performed under hydrous conditions crystallize magnetite and phlogopite at relatively high temperature. This early crystallization drives the glass composition towards a silica enrichment, resulting in a differentiation trend moving from phono-tephritic (Alban Hills parental composition) to phonolitic compositions. This is in contrast with micro-textural evidences showing late crystallization of magnetite and phlogopite in the natural products and with the composition of the juvenile products. On the contrary, in the CaCO3-bearing experiments (i.e., simulating magma-carbonate interaction) the magnetite and phlogopite stability fields are strongly reduced. As a consequence, the melt differentiation is mainly controlled by the cotectic crystallization of clinopyroxene and leucite, resulting in a differentiation trend moving towards K-foiditic compositions. These experimental results are in agreement with micro-textural features and chemical compositions of Alban Hills natural products and with the magmatic differentiation model inferred by geochemical data. Magma-carbonate interaction is not a rare process and its occurrence has been demonstrated for different plumbing systems. However, the uniqueness of the Alban Hills liquid line of descent suggests that the efficacy of the carbonate contamination process is controlled by different factors, the dynamics of the plumbing system being one of the most important.
    Description: INGV-DPC Project V3_1 Colli Albani Project FIRB MIUR “Development of innovative technologies for the environmental protection from natural events”.
    Description: Published
    Description: On line First
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: JCR Journal
    Description: reserved
    Keywords: Alban Hills ; ultrapotassic rocks ; experimental petrology ; magma-carbonate interaction ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
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  • 54
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    S–Cl–F degassing pattern of water-rich alkali basalt: Modelling and relationship with eruption styles on Mount Etna volcano (2007)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Our knowledge of the degassing pattern of sulphur, chlorine and fluorine during ascent and eruption of basaltic magmas is still fragmental and mainly limited to water-poor basalts. Here we model and discuss the pressure-related degassing behaviour of S, Cl and F during ascent, differentiation and extrusion of H2O–CO2-rich alkali basalt on Mount Etna (Sicily) as a function of eruptive styles. Our modelling is based on published and new melt inclusion data for dissolved volatiles (CO2, H2O, S, Cl, F) in quenched explosive products from both central conduit (1989–2001) and lateral dyke (2001 and 2002) eruptions. Pressures are obtained from the dissolved H2O and CO2 concentrations, and vapour–melt partition coefficients of S, Cl and F are derived from best fitting of melt inclusion data for each step of magma evolution. This allows us to compute the compositional evolution of the gas phase during either open or closed system degassing and to compare it with the measured composition of emitted gases. We find that sulphur, chlorine and fluorine begin to exsolve at respective pressures of ∼140 MPa, ∼100 MPa and ≤10 MPa during Etna basalt ascent and are respectively degassed at 〉95%, 22–55%, and ∼15% upon eruption. Pure open system degassing fails to explain gas compositions measured during either lateral dyke or central conduit eruptions. Instead, closed-system ascent and eruption of the volatile-rich basaltic melt well accounts for the time-averaged gas composition measured during 2002-type lateral dyke eruptions (S/Cl molar ratio of 5±1, 35% bulk Cl loss). Extensive magma fragmentation during the most energetic fountaining phases enhances Cl release (55%) and produces a lower S/Cl ratio of 3.7, as actually measured. Comparatively slower magma rise in the central conduits of Etna favours both sulphide saturation of the melt and greater chlorine release (55%), resulting in a distinct S/Cl evolution path and final ratio in eruptive gas. In both eruption types, any previous bubble–melt separation at depth leads to increased S/Cl and S/F ratios in emitted gas. High S/Cl ratios measured during some discrete eruptive events can thus be explained by transitions from closed (deep) to open (shallow) system degassing, with differential gas transfer extending down to ∼2 km depth below the vents. This depth coincides with the base of the volcanic pile where structural discontinuities and the high magma vesicularity (60%) may favour separate gas flow. Finally, the excess S–Cl–F gas discharge through Etna summit craters during non-eruptive periods requires a mixed supply from shallow magma degassing in the volcanic conduits and deeper-derived SO2-rich bubbles from the sub-volcano plumbing system. Our modelling provides a useful reference framework for interpreting the monitored variations of S, Cl and F in Mount Etna gas emissions as a function of volcanic activity. More broadly, the observations made for S, Cl and F degassing on Etna may apply to other basaltic volcanoes with water-rich magmas, such as in arcs.
    Description: Published
    Description: 772-786
    Description: reserved
    Keywords: Mt Etna ; volatiles ; magma degassing ; eruptive mechanisms ; modelling ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
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  • 55
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    Textural effects of steady state behaviour of the Stromboli feeding system (2007)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The exceptionally persistent activity of Stromboli volcano has lasted for at least 1400 years. The normal strombolian activity is periodically interrupted by more energetic explosions (1–2 per year) and by sporadic effusive episodes (every 10–20 years). Normal activity and effusive episodes are characterized by crystal-rich high-K to shoshonitic basalts issuing from a volatile-poor shallow system. Crystal-poor pumice are emitted only during more violent explosions, and are thought to derive from deep pulses of volatile-rich magma. Shallow level degassing induces massive crystallization of deep pulses of feeding magma that, continuously mixing with the resident one, produces the crystal-rich shoshonite of the persistent activity. We examined the crystallization history of the crystal-rich, shallow reservoir using plagioclase Crystal Size Distribution (CSD) analysis of scoriae and lavas emitted in the past twenty years. CSDs show a linear dependence from crystal size in the size interval 0.06–1.2 mm; number density of larger crystals is biased by right hand truncation effects. CSDs slopes and intercepts are quite constant during the whole considered time span revealing a system that is close to the equilibrium also from a kinetic point of view. The linear crystal size distribution are reached by the system through episodes of growth and resorption, respectively occurring in the degassed and undegassed magma during the continuous mixing in the feeding system. Plagioclase net growth rate (2*10−11 cm/s) results from a balance of growth (10−10 cm/s) and resorption episodes which induce spectacular zoning and resorption textures in crystals larger than 200 μm. CSDs of mafic phases cannot be accurately acquired on each single sample due to poor counting statistics; the evaluation of pyroxene and olivine CSD on the whole data set, however, confirms the conclusions acquired from plagioclase CSDs.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: crystal size distribution ; plagioclase growth ; magma residence time ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
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  • 56
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    Enclaves provide new insights on the dynamics of magma mingling: a case study from Salina Island (Southern Tyrrhenian Sea, Italy) (2007)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Three lava flows (hereafter, flows A, B, and C) from Salina Island (Italy) consist of basaltic andesitic enclaves dispersed in a dacitic matrix. Enclaves represent 8–12 vol.% of the erupted magma. The number of enclaves and the surface covered by the enclaves at each outcrop do not vary significantly with the distance from the vent in the flows A and B. These feature reflect the dynamics of magma mingling within the reservoir and not the kinematics of the lava flow. In the flow C, these parameters vary irregularly. The statistical entropy S(t) of the enclaves, which is a measure of their spatial distribution (dispersion), is estimated in outcrops located at different distance from the vent. The Kolmogorov–Sinai entropy rate k, which describes the variations of S(t) with time, is also determined. In the lava flow A, S(t) increases linearly with time t for 0btb0.4; k is 0.04. For tN0.5, S(t) attains its maximum value and maintains constant with increasing t. In the lava flow B, S(t) linearly increases with t, and k is 0.01. In the lava flow C, there is not correlation between S(t) and t. The comparison between the results from the analysis of the Porri enclaves and those from numerical experiments on the variation of S(t) in chaotic advective mixing systems and from previous experimental models on magma mixing, allow us to draw some conclusions on dynamics of the basaltic andesite– dacite mingling in the magma chamber. Fully chaotic magma mingling systems show three evolution stages. An initial stage, which is unknown because of the disruption of the initial configuration of the interacting magmas, a second stage characterized by a linear increase of the statistical entropy with time, and a third stage, in which the uniformity of the system is reached, and the entropy does not vary with increasing time. A system in which the uniformity is never attained, is characterized by irregular variations of S(t) with time. In the flows A and B, the relations between S(t) and t are consistent with those of a fully chaotic dynamics possibly associated to convection. The basaltic andesite was uniformly distributed in the dacitic host due to the occurrence of convective movements driven by the injection of the basaltic andesite within the dacitic chamber. The mingling system recorded by the lava flow A evolved with a higher rate with respect to that of the flow B. This suggests that chaotic advection (stirring and folding) is more efficient in the magmatic system A than in B. On the contrary, the mingling system C is characterized by a non-uniform distribution of the basaltic andesite within dacite. This reflects the occurrence of a dynamics in which stirring and folding processes do not operate efficiently and are unable to uniformly distribute the dispersed phase within the continuous one. The decrease of k from A to B, and the lack of a measurable k in C, along with the observation that A and B were emitted before C, indicate that the efficiency of advective movements within the Porri magma chamber declined with decreasing time. Mingled magmas characterized by a homogeneous spatial distribution of enclaves or an initially inhomogeneous distribution evolving towards a homogeneous one are indicative of efficient advection processes that may favor magma mixing. Mingled magmas characterized by an inhomogeneous distribution of enclaves suggest low dynamical interaction between the two end-members. Magma mixing is not allowed.
    Description: Published
    Description: 128–140
    Description: JCR Journal
    Description: reserved
    Keywords: volcanology ; petrology ; magma mingling ; enclaves ; lava flows ; entropy ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
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  • 57
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    The December 2002–July 2003 effusive event at Stromboli volcano, Italy: Insights into the shallow plumbing system by petrochemical studies (2007)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: On 28 December 2002, the persistent Strombolian activity at Stromboli was interrupted by the sudden onset of lava emission onto the Sciara del Fuoco slope, a horseshoe-shaped depression on the NW flank of the volcano. The effusive episode went on until 22 July 2003 and produced a cumulative volume of lavas of 11×106 m3 ranking the event as the largest occurred in the past 30 years. The eruptive vents were mainly located in the NE sector of the Sciara del Fuoco depression, at an elevation of 550–600 m a.s.l. On 30 December, the eastern portion of the Sciara del Fuoco collapsed producing a tsunamigenic landslide. On 5 April 2003, a paroxysmal eruption occurred at the summit craters during which crystal-poor pumiceous products were emitted. The paroxysm did not interrupt the lava emission. The Strombolian activity at the summit craters gradually resumed starting from March 2003 and fully recovered by the end of July. Periodic sampling of the lava at the active vents was carried out during the entire effusive event. All the analysed samples are shoshonitic basalts (SiO2 48.5–50.4 wt.%; K2O 2.1–2.4 wt.%) in the range of composition observed in the products erupted during the past 20 years. They bear about 50 vol.% zoned crystals of plagioclase An90–60, diopside–augite and olivine Fo70–73 in a compositionally homogeneous shoshonitic groundmass. Bulk rock major and trace element contents measured with different methodologies at different laboratories show only minor variations. Sr and Nd isotope ratios are close to those of the crystal-rich scoriae erupted in the previous years. Despite of small compositional variations related to the emptying of the zoned topmost portion of the conduit, the data show that the switch from Strombolian explosive to effusive activity is not associated with changes of the textures and composition of the erupted products. Slight but somehow systematic variation of trace elements and isotope ratios between products erupted before and after the 5 April eruption are likely accounted by limited mixing between the fresh, volatile-rich, crystal-poor, magma erupted as pumice during the paroxysm, and the volatile-poor, crystal-rich magma feeding the lava flow. The uniform composition of the erupted lava indicates the presence of a large volume of well-mixed, crystal-rich, homogeneous magma residing in the shallow plumbing system of the volcano. Two possible trigger mechanism of the effusive event are here proposed: (i) a discrete input of fresh magma into the lower part of the shallow magmatic system occurred some months before the eruption and was followed by crystallisation, degassing and mixing with the crystal-rich shallow magma which re-homogenised the system. These processes eventually led to the rise of the magma at a higher level and failure of the conduit walls. (ii) The onset of the effusion may represent the consequence of a gradual rise of the magma level in the conduits occurred in the past two decades. The process of progressive refilling, initiated after the 1985 effusive eruption, ultimately culminated on 28 December 2002 with the failure of the conduit wall and the opening of vents 100–150 m below the summit craters
    Description: Published
    Description: 263-284
    Description: JCR Journal
    Description: reserved
    Keywords: Stromboli volcano ; Aeolian Islands ; 2002–2003 eruption ; Mineralogy ; Geochemistry ; Sr isotope ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
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  • 58
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    Textural effects of steady state behaviour of the Stromboli feeding system (2007)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The exceptionally persistent activity of Stromboli volcano has lasted for at least 1400 years. The normal strombolian activity is periodically interrupted by more energetic explosions (1–2 per year) and by sporadic effusive episodes (every 10–20 years). Normal activity and effusive episodes are characterized by crystal-rich high-K to shoshonitic basalts issuing from a volatile-poor shallow system. Crystal-poor pumice are emitted only during more violent explosions, and are thought to derive from deep pulses of volatile-rich magma. Shallow level degassing induces massive crystallization of deep pulses of feeding magma that, continuously mixing with the resident one, produces the crystal-rich shoshonite of the persistent activity. We examined the crystallization history of the crystal-rich, shallow reservoir using plagioclase Crystal Size Distribution (CSD) analysis of scoriae and lavas emitted in the past twenty years. CSDs show a linear dependence from crystal size in the size interval 0.06–1.2 mm; number density of larger crystals is biased by right hand truncation effects. CSDs slopes and intercepts are quite constant during the whole considered time span revealing a system that is close to the equilibrium also from a kinetic point of view. The linear crystal size distribution are reached by the system through episodes of growth and resorption, respectively occurring in the degassed and undegassed magma during the continuous mixing in the feeding system. Plagioclase net growth rate (2 × 10− 11 cm/s) results from a balance of growth (10− 10 cm/s) and resorption episodes which induce spectacular zoning and resorption textures in crystals larger than 200 μm. CSDs of mafic phases cannot be accurately acquired on each single sample due to poor counting statistics; the evaluation of pyroxene and olivine CSD on the whole data set, however, confirms the conclusions acquired from plagioclase CSDs.
    Description: Published
    Description: 86-98
    Description: 2.4. TTC - Laboratori di geochimica dei fluidi
    Description: JCR Journal
    Description: reserved
    Keywords: crystal size distribution ; plagioclase growth ; magma residence time ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
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  • 59
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    Coseismic and postseismic displacements related with the 1997 earthquake sequence in Umbria-Marche (central Italy) (2007)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: We study the coseismic and postseismic displacements related with the 1997 Umbria-Marche earthquake sequence by means of leveling lines along a deformed aqueduct located in the epicentral area. Comparing the 1960 and 10/1997 measurements we obtain 0.49 0.10 m of coseismic displacement distributed along 3 km across the normal fault zone. Modeling of the coseismic surface dislocation is obtained from a combination of low angle (38°) faults at depth and high angle (80°) upper fault branches. The best fit model indicates that the upper branches stop at 0.4 km below the ground surface and have 60% of slip with respect to the lower faults. The postseismic displacement measured during 1998 is 0.18 m and represents 36% of the apparent coseismic deformation. Moderate earthquakes in the Apennines and related surface deformation may thus result from curved faults that reflect the brittle-elastic properties of the uppermost crustal structures.
    Description: Data collection was made while both authors were at Istituto di Ricerca per la Tettonica Recente – CNR (GNDT Project), Roma, Italy. M. Copparoni (ASM, Foligno) and M. Raponi and S. Pacico (Studio Topografico s.n.c., Foligno) provided data about aqueduct and leveling lines. Analysis of data and modeling were done while RB was visiting EOST-IPG, Strasbourg, France. Preparation of the paper benefited from discussion with R. Armijo, S. Barba, P. Gomez and G. Valensise. A. Amato and an anonymous reviewer are thanked for their constructive remarks.
    Description: Published
    Description: 2695–2698
    Description: JCR Journal
    Description: open
    Keywords: Coseismic displacement ; postseismic displacement ; earthquake fault ; Colfiorito, Italy ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations ; 04. Solid Earth::04.04. Geology::04.04.01. Earthquake geology and paleoseismology ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
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  • 60
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    Surface movements in Bologna (Po Plain — Italy) detected by multitemporal DInSAR (2007)
    Elsevier
    Details
    Publication Date: 2019-10-18
    Description: We studied the surface deformations affecting the southeastern sector of the Po Plain sedimentary basin, in particular the area of Bologna. To this aim an advanced DInSAR technique, referred to as DInSAR–SBAS (Small BAseline Subset), has been applied. This technique allows monitoring the temporal evolution of a deformation phenomenon, via the generation of mean deformation velocity maps and displacement time series from a data set of acquired SAR images. In particular, we have processed a set of SAR data acquired by the European Remote Sensing Satellite (ERS) sensors and compared the achieved results with optical levelling measurements, assumed as reference. The surface displacements detected by DInSAR SBAS from 1992 to 2000 are between 10 mm/year in the historical part of Bologna town, and up to 59 mm/year in the NE industrial and agricultural areas. Former measurements from optical levelling referred to 1897 show 2–3 mm/year vertical movements. This trend of displacement increased in the second half of the 20th century and the subsidence rate reached 60 mm/year. We compared the more recent levelling campaigns (in 1992 and late 1999) and DInSAR results from 1992 to 1999. The standard deviation of the difference between levelling data, projected onto the satellite Line Of Sight, and DInSAR results is 2 mm/year. This highlights a good agreement between the measurements provided by two different techniques. The explanation of soil movements based on interferometric results, ground data and geological observations, allowed confirming the anthropogenic cause (surface effect due to the overexploitation of the aquifers) and highlights a natural, tectonic, subsidence.
    Description: Published
    Description: 304-316
    Description: 1.10. TTC - Telerilevamento
    Description: JCR Journal
    Description: partially_open
    Keywords: InSAR ; surface deformation ; SAR interferometry ; 04. Solid Earth::04.03. Geodesy::04.03.99. General or miscellaneous ; 04. Solid Earth::04.03. Geodesy::04.03.06. Measurements and monitoring ; 04. Solid Earth::04.03. Geodesy::04.03.07. Satellite geodesy ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
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  • 61
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    Evidence of active tectonics on a Roman aqueduct system (II–III century A.D.) near Rome, Italy (2006)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: In this paper we describe evidence of strong tectonic deformation affecting two aqueducts of Roman age (II–III century A.D.). The channels are located approximately 20 km northeast of Rome along the ancient Via Tiburtina. Brittle and ductile deformation affects these two structures, including extensional joint systems, NE-oriented faults, and horizontal distortion. This deformation is consistent with rightlateral movement on major N-striking faults, and represents the first evidence that tectonic deformation took place in historical times in the vicinity of Rome, with local strike–slip movement superimposed on a regional extensional fault system.
    Description: Published
    Description: 679–690
    Description: reserved
    Keywords: Strike–slip tectonics ; Active tectonics ; Geo-archaeology ; Rome ; Italy ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
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  • 62
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    Solubility and speciation of sulfur in silicate melts: The Conjugated Toop-Samis-Flood-Grjotheim (CTSFG) model (2006)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: A Conjugated Toop-Samis-Flood-Grjotheim (CTSFG) model is developed by combining the framework of the Toop-Samis polymeric approach with the Flood-Grjotheim theoretical treatment of silicate melts and slags. Electrically equivalent ion fractions are computed over the appropriate matrixes (anionic and cationic) in a Temkin notation for fused salts, and are used to weigh the contribution of the various disproportionation reactions of type: M2/pO(melt)+ 1/2S(gas)+M2/pS(melt)+1/2O2(gas) M2/po(melt)+1/2S2(gas)+3/2O2(gas)-M2/pSO4(melt)v being the charge of the generic Mp-1 cation. The extension of the anionic matrix is calculated in the framework of a previously developed polymeric model (Ottonello et al., 2001), based on a parameterization of Lux-Flood acid-base properties of melt components. Model activities follow the Raoultian behavior implicit in the Temkin notation, without the needs of introducing adjustable parameters. The CTSFG model is based on a large amount of data available in literature and exhibits a satisfactory heuristic capability, with virtually no compositional limits, as long as the structural role given to each oxide holds. The model may be employed to compute gas-melt equilibria involving sulfur and allows computing sulfide and sulfate contents of silicate melts whenever the fugacity of a gaseous sulfur species and oxygen are known. Alternatively, the model calculates the oxidation state of the system (i.e., oxygen fugacity), whenever an analytical determination of either sulfide/sulfate or ferrous/ferric ratios in the melt is provided. Calculated sulfide and sulfate capacities allow the estimates of sulfur abundance in various melts of geological interest, both under anhydrous and hydrous conditions or, alternatively, of fS2, given fO2 and the bulk sulfur content. In this case, fSO2 and fH2S may be eventually computed along the water-sulfur-melt boundary provided fH2O is known.
    Description: Published
    Description: 801-823
    Description: partially_open
    Keywords: sulfur ; silicate melts ; 04. Solid Earth::04.04. Geology::04.04.05. Mineralogy and petrology ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.04. Thermodynamics
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    Seismotectonics of the Southern Apennines and Adriatic foreland: insights on active regional E-W shear zones from analogue modeling (2006)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: The active tectonics at the front of the Southern Apennines and in the Adriatic foreland is characterized by E-W striking, right-lateral seismogenic faults, interpreted as reactivated inherited discontinuities. The best studied among these is the Molise-Gondola shear zone (MGsz). The interaction of these shear zones with the Apennines chain is not yet clear. To address this open question we developed a set of scaled analogue experiments, aimed at analyzing: 1) how dextral strike-slip motion along a pre-existing zone of weakness within the foreland propagates toward the surface and affects the orogenic wedge; 2) the propagation of deformation as a function of displacement; 3) any insights on the active tectonics of Southern Italy. Our results stress the primary role played by these inherited structures when reactivated, and confirm that regional E-W dextral shear zones are a plausible way of explaining the seismotectonic setting of the external areas of the Southern Apennines.
    Description: INGV, Università degli Studi di Pavia
    Description: Published
    Description: 21
    Description: open
    Keywords: Active strike-slip fault ; sandbox model ; southern Italy ; 04. Solid Earth::04.01. Earth Interior::04.01.02. Geological and geophysical evidences of deep processes ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
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    Magma dynamics at mid-ocean ridges by noble gas kinetic fractionation: Assessment of magmatic ascent rates (2006)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Despite its impact in understanding oceanic crust formation and eruptive styles of related volcanism, magma dynamics at midocean ridges are poorly known. Here, we propose a new method to assess ascent rates of mid-ocean ridge basalt (MORB) magmas,as well as their pre- and sin-eruptive dynamics. It is based on the idea that a rising magma can reach a variable degree of both CO2 supersaturation in melt and kinetic fractionation among noble gases in vesicles in relation to its ascent rate through the crust. To quantify the relationship, we have used a model of multicomponent bubble growth in MORB melts, developed by extending the single-component model of Proussevitch and Sahagian [A.A. Proussevitch, D.L. Sahagian, Dynamics and energetics of bubble growth in magmas: analytical formulation and numerical modeling, J. Geophys. Res. 103 (1998), 18223–18251.] to CO2–He–Ar gas mixtures. After proper parameterization, we have applied it to published suites of data having the required features (glasses from Pito Seamount and mid-Atlantic ridges). Our results highlight that the investigated MORB magmas display very different ranges of ascent rates: slow rises of popping rock forming-magmas that cross the crust (0.01–0.5 m/s), slightly faster rates of energetic effusions (0.1–1 m/s), up to rates of 1–10 m/s which fall on the edge between lava effusion and Hawaiian activity. Inside a single plumbing system, very dissimilar magma dynamics highlight the large differences in compressive stress of the oceanic crust on a small scale. Constraints on how the systems of ridges work, as well as the characteristics of the magmatic source, can also be obtained. Our model shows how measurements of both the dissolved gas concentration in melt and the volatile composition of vesicles in the same sample are crucial in recognizing the kinetic effects and definitively assessing magma dynamics. An effort should be made to correctly set the studied samples in the sequence of volcanic submarine deposits where they are collected. Enhanced knowledge of a number of physical properties of gas-bearing MOR magmas is also required, mainly noble gas diffusivities, to describe multicomponent bubble growth at a higher confidence level.
    Description: Published
    Description: 138-158
    Description: partially_open
    Keywords: Bubble growth ; MORB ; Noble gas ; Kinetic fractionation ; Modeling ; 04. Solid Earth::04.04. Geology::04.04.07. Rock geochemistry ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.04. Thermodynamics
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    The strain path and kinematics of lava domes: An example from Lipari (2006)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: A circular dome from Lipari Island consists of latitic enclaves hosted in a rhyolitic magma. A strain analysis of the enclaves has been carried out and the pure shear (a) and simple shear (g) deformation, the vorticity number Wk and flow kinematics are determined. The axial ratio Rf of the enclaves and the angle f between the long axis of the enclaves and the transport direction are measured in 131 sites concentrated in the axial zone (z1), upper-distal zone (z2) and basal zone (z3) of the flow. The f values depict a pattern suggesting endogenous growth. In z1, a/g 〉 1. In z2, 1 〈 a 〈 1.35 and 1.8 〈 g 〈 0.5. In z3, 1 〈 a 〈 1.5 and 0.3 〈 g 〈 2.8. In z1, Wk 〈 0.5. In z2 and z3, Wk 〉 0.8. Lateral stretching due to the upward motion of magma from the conduit prevails in z1. Here the increase of pure shear strain from the bottom to the top reflects strain accumulation due to endogenous growth. z2 and z3 suffer simple shear deformation. In z3, the sense of shear is consistent with the transport direction. An opposite sense of shear characterizes z2. This is due to velocity gradients located in the lower and upper portions of the flow. The kinematics is viscous spreading in z1 and viscous gliding (hyperbolic flow) in z2â z3.Possible rupturing of the exterior may be important in z1, where lateral stretching occurs, and in z3, where g is at a maximum. The effusion rate is 1.93 m3/s. Strain rates calculated using structural data span a range from 1.9 to 5.8.10 6 s 1.
    Description: Published
    Description: 1-10
    Description: partially_open
    Keywords: lava domes ; kinematics ; emplacement mechanism ; strain analysis ; enclaves ; viscous flows ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks
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  • 66
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    Tectonic control on the eruptive dynamics at Mt. Etna Volcano (Sicily) during the 2001 and 2002–2003 eruptions (2005)
    Elsevier
    Details
    Publication Date: 2020-12-15
    Description: 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.
    Description: Published
    Description: 211-233
    Description: partially_open
    Keywords: 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
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  • 67
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    Dynamics of magma ascent and fragmentation in trachytic versus rhyolitic eruptions (2005)
    Elsevier
    Details
    Publication Date: 2020-10-29
    Description: We have performed a parametric study on the dynamics of trachytic (alkaline) versus rhyolitic (calc-alkaline) eruptions by employing a steady, isothermal, multiphase non-equilibrium model of conduit flow and fragmentation. The employed compositions correspond to a typical rhyolite and to trachytic liquids from Phlegrean Fields eruptions, for which detailed viscosity measurements have been performed. The investigated conditions include conduit diameters in the range 30–90 m and total water contents from 2 to 6 wt%, corresponding to mass flow rates in the range 106–108 kg/s. The numerical results show that rhyolites fragment deep in the conduit and at a gas volume fraction ranging from 0.64 to 0.76, while for trachytes fragmentation is found to occur at much shallower levels and higher vesicularities (0.81–0.85). An unexpected result is that low-viscosity trachytes can be associated with lower mass flow rates with respect to more viscous rhyolites. This is due to the non-linear combined effects of viscosity and water solubility affecting the whole eruption dynamics. The lower viscosity of trachytes, together with higher water solubility, results in delayed fragmentation, or in a longer bubbly flow region within the conduit where viscous forces are dominant. Therefore, the total dissipation due to viscous forces can be higher for the less viscous trachytic magma, depending on the specific conditions and trachytic composition employed. The fragmentation conditions determined through the simulations agree with measured vesicularities in natural pumice clasts of both magma compositions. In fact, vesicularities average 0.80 in pumice from alkaline eruptions at Phlegrean Fields, while they tend to be lower in most calc-alkaline pumices. The results of numerical simulations suggest that higher vesicularities in alkaline products are related to delayed fragmentation of magmas with this composition. Despite large differences in the distribution of flow variables which occur in the deep conduit region and at fragmentation, the flow dynamics of rhyolites and trachytes in the upper conduit and at the vent can be very similar, at equal conduit size and total water content. This is consistent with similar phenomenologies of eruptions associated with the two magma types.
    Description: Published
    Description: 93-108
    Description: partially_open
    Keywords: trachytic magma ; conduit flow ; eruption dynamics and numerical simulations ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
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  • 68
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    Thermal and geochemical constraints on the ‘deep’ magmatic structure of Mt. Vesuvius (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: A review of available and new isotopic data on rocks from Mt. Vesuvius together with geophysical and mineralogical data allow us to define a ‘deep’ complex magmatic reservoir where mantle-derived magmas arrive, stagnate and differentiate, and to constrain a thermal model, which describes the history and present state of the reservoir and its surrounding rocks. The top of the reservoir is located at about 8 km depth, and it extends discontinuously down to 20 km depth. The reservoir is hosted in densely fractured continental crustal rocks, where magmas and crust can interact, and, according to thermal modeling results, has been fed more than once in the last 400 ka. The hypothesis of crustal contamination is favored by the high temperatures reached by crustal rocks as a consequence of repetitive intrusions of magma. From the ‘deep’ reservoir magmas rise to form ‘shallow’ magma chambers at different depths, as already known in the literature, where they can undergo low-pressure differentiation and mixing and feed the volcanic activity.
    Description: Published
    Description: 1-12
    Description: partially_open
    Keywords: Magmatic system ; Crustal contamination ; Thermal modeling ; Isotope geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 69
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    Rapid morphological changes at the summit of an active volcano: reappraisal of the poorly documented 1964 eruption of Mount Etna (Italy) (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: While the eruptive record of Mount Etna is reasonably complete for the past 400 years, the activity of the early and late 1960s, which took place at the summit, is poorly documented in the scientific literature. From 1955 to 1971, the Central and Northeast Craters were the sites of long-lived mild Strombolian and effusive activity, and numerous brief episodes of vigorous eruptive activity, which led to repeated overflows of lava onto the external flanks of the volcano. A reconstruction of the sequence of the more important of these events based on research in largely obscure and nearly inaccessible sources permits a better understanding of the eruption dynamics and rough estimates of erupted volumes and of the changes to the morphology of the summit area. During the first half of 1964, the activity culminated in a series of highly dynamic events at the Central Crater including the opening of a fissure on the E flank of the central summit cone, lava fountains, voluminous tephra emission, prolonged strong activity with continuous lava overflows, and growth of large pyroclastic intracrater cones. Among the most notable processes during this eruption was the breaching of a section of the crater wall, which was caused by lateral pressure of lava ponding within the crater. Comparison with the apparently similar summit activity of 1999 allows us to state that (a) lava overflows from large pit craters at the summit are often accompanied by breaching of the crater walls, which represents a significant hazard to nearby observers, and that (b) eruptive activity in 1999 was much more complex and voluminous than in 1964. For 1960s standards however, the 1964 activity was the most important summit eruption in terms of intensity and output rates for about 100 years, causing profound changes to the summit morphology and obliterating definitively the former Central Crater.
    Description: Published
    Description: 203-218
    Description: partially_open
    Keywords: Mount Etna ; Summit eruption ; Crater morphology and Lava overflows ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
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  • 70
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    Pulsed lava effusion at Mount Etna during 2001 (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Effusion rate and degassing data collected at Mt. Etna volcano (Italy) in 2001 show variations occurring on time scales of hours to months. We use both long- and short-term data sets spanning January to August to identify this variation. The long data sets comprise a satellite- and ground-based time series of effusion rates, and the latter include field-based effusion rate and degassing data collected May 29–31. The satellite-derived effusion rates for January through August reveal four volumetric pulses that are characterized by increasing mean effusion rate values and lead up to the 2001 flank eruption. Peak effusion rates during these 23–57 day pulses were 1.2 m3 s-1 in Pulse 1 (1 Jan–4 Mar), 1.1 m3 s-1 in Pulse 2 (5 Mar–21 Apr), 4.2 m3 s-1 in Pulse 3 (24 Apr–18 Jun), 8.8 m3 s-1 in Pulse 4 (23 Jun–16 Jul), and 22.2 m3 s-1 during the flank eruption (17 Jul–9 Aug). Rank-order analysis of the satellite data shows that effusion rate values during the 2001 flank eruption define a statistically different trend than Etna's persistent activity from Jan 1 to Jul 17. Data prior to the flank eruption obey a power-law relationship that may define an effusion rate threshold of ~3–5 m3 s-1 for Etna's typical persistent activity. Our short-term data coincide with the satellite-derived peak effusion period of Pulse 3. Degassing (at-vent puff frequency) shows a general increase from May 29 to 31, with hour-long variations in both puff frequency and lava flow velocity (effusion rate). We identify five 3–14 h degassing periods that contain 26 shorter (19–126 min-long) oscillations. This variation shows some positive correlation with effusion rate measurements during the same time period. If a relationship between puff frequency and effusion rate is valid, we propose that their short-term variation is the result of changes in the supply rate of magma to the near-vent conduit system. Therefore, these short-term data provide some evidence that the clear weeks- to months-long variation in Etna's effusive activity (January–August 2001) was overprinted by a minutes- to hour-scale oscillation in shallow supply.
    Description: Published
    Description: 231-246
    Description: partially_open
    Keywords: effusion rate ; degassing ; oscillation ; shallow supply and Etna ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
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  • 71
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    Birth, growth and morphologic evolution of the `Laghetto´ cinder cone during the 2001 Etna eruption (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: We have undertaken detailed observations of the formation of the `Laghetto´ cinder cone, a new cone that formed during a 2-week period of intense activity in Piano del Lago, on the upper slopes of Mount Etna in summer 2001. We describe the events leading to the formation of a small graben, the formation of pit craters on the base of the graben, the onset of phreatomagmatic activity, a transition to intense Strombolian activity, and a return to phreatomagmatic activity as the eruption came to an end. We discuss the reasons for these transitions, and describe the morphological development of the cone during these events. Arcuate cracks on the southern part of the cone were related to withdrawal of magma at the end of the eruption. Other slope instabilities that developed during the eruption include the formation of small radial grain flows on the outer flanks of the cone and the collapse into the crater of part of the crater rim. Some of the failure planes we observed were first identified using a FLIR TM 695 thermal infrared camera. This is the first time that infrared thermography has been used to detect instability of volcanic structures. Results obtained during this test case demonstrate that thermal cameras are a very useful tool for studies of volcanic instability.
    Description: Published
    Description: 225-239
    Description: partially_open
    Keywords: Etna volcano ; cinder cone ; volcano instability ; thermal images ; phreatomagmatic activity ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
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  • 72
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    Relative roles of rifting tectonics and magma ascent processes: Inferences from geophysical, structural, volcanological, and geochemical data for the Neapolitan volcanic region (southern Italy) (2005)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: The Neapolitan volcanic region is located within the graben structure of the Campanian Plain (CP), which developed between the western sector of the Appenine Chain and the eastern margin of the Tyrrhenian Sea. Two volcanic areas, spaced less than 10 km apart, are situated within the CP: the Somma-Vesuvius Volcano (SVV) and the Phlegraean Volcanic District (PVD). SVV is a typical stratovolcano, whereas PVD, including Campi Flegrei, Procida, and Ischia, is composed mostly of monogenetic centers. This contrast is due to different magma supply systems: a widespread fissure-type system beneath the PVD and a central-type magma supply system for the SVV. Volcanological, geophysical, and geochemical data show that magma viscosity, magma supply rate, and depth of magma storage are comparable at PVD and SVV, whereas different structural arrangements characterize the two areas. On the basis of geophysical data and magma geochemistry, an oblique-extensional tectonic regime is proposed within the PVD, whereas in the SVVarea a compressive stress regime dominates over extension. Geophysical data suggest that the area with the maximum deformation rate extends between the EW-running 41st parallel and the NE-running Magnaghi-Sebeto fault systems. The PVD extensional area is a consequence of the Tyrrhenian Sea opening and is decoupled from the surrounding areas (Roccamonfina and Somma-Vesuvius) which are still dominated by Adriatic slab dynamics. Spatially, we argue that the contribution of the asthenospheric wedge become much less important from W-NW to E-SE in the CP. The development of the two styles of volcanism in the CP reflects the different tectonic regimes acting in the area.
    Description: Published
    Description: 1-25
    Description: partially_open
    Keywords: Volcanic styles ; Tectonic setting ; Neapolitan volcanic region ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
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  • 73
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    2001 flank eruption of the alkali- and volatile-rich primitive basalt responsible for Mount Etna's evolution in the last three decades (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Since the early 1970s enhanced eruptive activity of Mount Etna has been accompanied by selective geochemical changes in erupted lavas, among which a gradual increase of alkalis whose origin is still debated. Here we provide further insight into the origin of this recent evolution, based on a detailed study of the chemistry and dissolved volatile content of melt inclusions trapped in olivine crystals of unusual plagioclase-poor primitive basalt that was extruded during a highly explosive flank eruption in July–August 2001. Two types of lava were erupted simultaneously along a N–S fracture system. Trachybasalts from the upper vents (2950–2700 m) were simply drained out by fracturing of the central volcanic conduit. They are identical to summit crater lavas and contain Mg-poor olivines (Fo70–72) with evolved and volatile-poor melt inclusions that represent late-stage crystallisation during shallow open conduit degassing. In contrast, plagioclase-poor basalt (80% of total) extruded through the lower vents (2550–2100 m) derived from lateral dyke intrusion of a more primitive and volatile-rich magma across the sedimentary basement. This primitive melt is best preserved in rare Fo82.4–80.5 skeletal olivines present in lapilli deposits from the most powerful activities at the 2550 m vent. Its high dissolved contents of H2 O (3.4 wt.%), CO2 (0.11 to 0.41 wt.%), S (0.32 wt.%), Cl (0.16 wt.%) and F (0.094 wt.%) point to its closed system ascent from ∼400 to 250 MPa (∼12 to 6.5 km depth b.s.l.). However, the predominance of euhedral olivine phenocrysts with common reverse zoning (cores Fo76–78 and rims Fo78–80) and decrepited inclusions shows that most of the erupted basalt derived from a slightly more evolved, crystallizing body of the same magma that was invaded by the uprising primitive melt prior to erupting. The few preserved inclusions in these olivines indicate pre-eruptive storage of that magma body at about 5 km depth b.s.l., in coherence with seismic data. We propose that the 2001 flank eruption resulted from gradual overpressuring of Etna's shallow plumbing system due to the influx of volatile-rich primitive basalt that may have begun several months in advance. We find that this basalt is much richer in alkalis (2.0 wt.% K2 O) and has higher S/Cl (2.0) but lower Cl/K and Cl/F ratios than all pre-1970s Etnean lavas (1.4 wt.% K2 O, S/Cl=1.5), as further exemplified by melt inclusions in entrained olivine xenocrysts. Combining these new observations with previously published data, we argue that the 2001 basalt represents a new alkali-rich basic end-member feeding Mt. Etna, only few amount of which had previously been extruded during a 1974 peripheral eruption and, more recently, during brief paroxysmal summit events. Over the last three decades this new magma has progressively mixed with and replaced the former K-poorer trachybasalts filling the plumbing system, leading to extrusion of gradually more primitive and alkali-richer lavas. Its geochemical singularities cannot result from shallow crustal contaminations. Instead, they suggest the involvement of an alkali-richer but Cl-poorer arc-type component during recent magma genesis beneath Etna.
    Description: Published
    Description: 1-17
    Description: partially_open
    Keywords: Mt. Etna ; volatiles ; degassing ; eruptive mechanism ; magma geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data
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  • 74
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    Development of tumuli in the medial portion of the 1983 aa flow-field, Mount Etna, Sicily (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: A number of tumuli formed on the aa-dominated lava fan complex which developed in the medial zone of the 1983 flow-field of Mount Etna during the later stages of the eruption. This complex flow-field formed on shallow sloping ground below a scarp between 1900 and 1700 m asl. A major tube system fed a branching tube network in the fan complex. Numerous tumuli and break-outs of lava formed in the fan. Three main types of tumulus are identified: (1) Focal tumuli, which are formed from the break-up and uplift of `old´, thick lava crust and themselves become sustained sites for the distribution of lava both as flows and within distributary tubes. These focal tumuli are significant centres associated with major tubes. (2) Satellite tumuli, which are typically elongate, whale-back shaped features that branch out from focal tumuli. These satellite tumuli were initially lava flows erupted from a focal tumulus. The crust of the flow slowed or came to a halt and the rigid crust became uplifted and fractured, forming a dome-shaped ridge feature. These satellite tumuli continued to be fed from the focal tumulus and became sites of lava emission with numerous break-outs. (3) Distributary tumuli formed on the fan associated with short-lived break-outs from tubes and are relatively simple structures formed from limited effusion of toey lobes and pahoehoe lava. The major tumuli on the fan complex show distinct dilation fractures. The fracture surfaces provide good exposure of the crust and three distinct zones are recognised – an upper zone showing columnar jointing, a middle zone consisting of planar fracture surfaces and a basal zone with distinctive banded planar fracture surfaces showing evidence of both brittle and ductile formation. Using these data a model is proposed for tumulus growth. Field analysis of the fan complex shows how it was fed by a branching tube system, leading to flow thickening, formation of tumuli and numerous ephemeral boccas.
    Description: Published
    Description: partially_open
    Keywords: aa lava flow-field ; Mount Etna ; tumulus ; lava crust and lava tubes. ; 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
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  • 75
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    Contrasting triggering mechanisms of the 2001 and 2002–2003 eruptions of Mount Etna (Italy) (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Mount Etna produced two significant eruptions in 2001 and 2002–2003, which we have analysed using geological, seismic and deformation data. These eruptions showed some similarities, such as the activating of two magmatic plumbing systems (central–lateral and eccentric), but they differed in their triggering mechanisms. While the 2001 eruption was largely the result of the emplacement of a N–S eccentric dike (independent from the central conduits) consistent with E–W regional extension, the 2002–2003 eruption occurred in response to a major flank slip on the eastern and southeastern sides of the volcano. This is demonstrated by the spatial and temporal distribution of seismicity and deformation preceding and accompanying the two eruptions. During the months prior to the 2001 eruption, most epicenters were concentrated on the southern flank, at depths of 5–15 km below sea level. During the 4 days before the eruption, earthquake hypocenters migrated to shallower levels (from 5 km bsl. upward) indicating the emplacement of the eccentric dike. This is confirmed by the patterns of ground fracturing observed in the field and deformation documented by electronic distance measurements (EDM). In contrast, the months before the 2002–2003 eruption were characterised by shallower seismicity, mainly concentrated along the active faults bordering the slipping flank sector. Flank slip accelerated in September 2002 and a second, more vigorous acceleration of flank slip occurred on 26–27 October 2002, accompanying the opening of eruptive vents. The very short (2 h) seismic crisis preceding the onset of eruptive activity stands in neat contrast with the 4 days of intense seismicity before the 2001 eruption. Subsequently, flank slip-deformation extended all over the eastern and southeastern flanks of the volcano, causing serious damage in this sector. The events of 2001–2003 can be seen as a continuous chain of intimately interacting processes including regional tectonics, magma accumulation and eruption, and flank instability. In this scenario the 2001 eruption led to increased flank instability that subsequently accelerated and culminated with the massive flank slip, which in turn facilitated the 2002–2003 eruption. This sequence of events points to a long-term feedback mechanism between magmatism and flank instability at Etna.
    Description: Published
    Description: 235-255
    Description: partially_open
    Keywords: eruption triggering ; central–lateral vs. eccentric eruptions ; flank instability and slip ; volcano-tectonics ; Mt. Etna ; instrumental monitoring ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 76
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    A multidisciplinary approach to detect active pathways for magma migration and eruption at Mt. Etna (Sicily, Italy) before the 2001 and 2002-03 eruptions (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Two strong flank eruptions occurred in July–August 2001 and from late October 2002 to late January 2003 at Mt. Etna volcano. The two eruptions mainly involved the upper southern flank of the volcano, a particularly active area during the last 30 years, damaging several tourist facilities and threatening some villages. The composite eruptive activity on the upper southern flank of Mt. Etna during 2001–2003 has confirmed “a posteriori” the results of a multidisciplinary study, started well before its occurrence by combining geological, seismic and geochemical data gathered in this part of the volcano. We were able, in fact, to highlight fractured zones likely to be re-activated in the near future in this area, where the largest majority of eruptive fissures in the recent past opened along N120° to N180° ranging directions. The spatial distribution of earthquake epicentres during the period June 30th 2000–June 30th 2001 showed the greatest frequency in a sector compatible with both the direction of the main fissures of the pre-2001 period and that of the 2001 and 2002 lateral eruptions. Soil CO2 and soil temperature surveys carried out in the studied area during the last 3 years have revealed anomalous release of magmatic fluids (mainly CO2 and water vapour) along some NNW–SSE-trending volcano-tectonic structures of the area even during inter-eruptive periods, indicating persistent convective hydrothermal systems at shallow depth connected with the main feeder conduits of Etna. The temporal changes in both seismic and geochemical data from June 30th, 2000 to June 30th, 2001 were compared with the evolution of volcanic activity. The comparison allowed to recognize at least two sequences of anomalous signals (August to December 2000 and April to June 2001), likely related to episodes of step-like magma ascent towards the surface, as indicated by the following eruptive episodes. The N120° to N180° structural directions are in accord with one of the main structural lines affecting eastern Sicily; they would be important pathways for magma uprise to the surface that will keep on feeding the eruptive activity of Etna in the near future. This study also pointed out the high instability of the southern slope of Etna, a sector where the potential hazard by lava flow invasion will remain high also in the near future.
    Description: Published
    Description: 20
    Description: partially_open
    Keywords: Mt. Etna ; fault detection ; soil gas ; historical eruptive fissures ; eruptive activity ; local seismicity ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
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  • 77
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    Evidence of deep magma degassing and ascent by geochemistry of peripheral gas emissions at Mount Etna (Italy): Assessment of the magmatic reservoir pressure (2005)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: Five gas discharges in the area of Mount Etna volcano (Italy) and in the near Hyblean plateau have been monitored since 1996. All the emissions displayed low contributions from crustal fluids, whereas magmatic gases were the main component. Selective dissolution of these gases into hydrothermal aquifers has been recognized and modeled, allowing us to calculate the original composition of the magma-released gases. The inferred composition of the magmatic gases exhibits synchronous variations of He/Ne and He/CO2 ratios, which are coherent with the magma degassing process. On the basis of numerical simulations of volatile degassing from Etnean basalts we have computed the initial and final pressures of the magma batches feeding the emissions. We thus can define the levels of the Etna plumbing system where magmas are stored. Pressure values were around 360 and 160 MPa for initial and final stages, respectively, meaning related depths of about 10 and 3 km below sea level, matching those obtained by geophysical investigations for the deep and shallow magma reservoirs. In addition, we have been able to recognize episodes of magma migration from the deeper reservoir toward the shallow one. An important magma injection into the shallow storage volume was detected during the onset of the 2001 eruption (17 July). No further injection had taken place during this period until September 2001, providing a possible reason for the quick exhaustion of the eruption. In view of this we suggest that the sampled emissions are a powerful geochemical tool to investigate the Etna’s plumbing system and its magma dynamics, as well as the development of eruptive events.
    Description: Published
    Description: 2463
    Description: partially_open
    Keywords: gas geochemistry ; magma degassing ; modeling ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 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::04.08.06. Volcano monitoring
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  • 78
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    Mount Etna: Geochemical signals of magma ascent and unusually extensive plumbing system (2005)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: Five years of gas monitoring from selected sites suggest that Mt Etna’s plumbing system is much more extensive than previously reported. It extends at least 40 km SW from the volcano’s boundary along the NE-SW regional fault, where it discharges about 200 tons/day of gas, containing helium with mantle-type isotopic composition. Synchronous variations of 3He/4He isotopic ratios in gas sampled at sites located 60 kilometers apart have allowed us to detect pulses of ascending magma in the plumbing system, thus providing a powerful tool for eruption forecasting. Following summer 2001 eruption, the still increasing trend of the 3He/4He ratios indicates that magma storage is even now occurring at a shallow depth. Hence, the volcano maintains a high capacity to re-erupt within the next few months.
    Description: Published
    Description: 1057
    Description: partially_open
    Keywords: helium isotopes ; geochemical monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 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)
    Type: article
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  • 79
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    Active geodynamics of the central Mediterranean Sea: Tensional tectonic evidences in western Sicily from mantle-derived helium (2005)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: We report results on the measured high 3He/4He isotope ratio in western Sicily, interpreted together with the heat data. The study of this sector of the Europe-Africa interaction is crucial to a better understanding of the tectonics and the geodynamical evolution of the central Mediterranean area. The estimated mantle-derived helium fluxes in the investigated areas are up to 2–3 orders of magnitude greater than those of a stable continental area. The highest flux, found in the southernmost area near the Sicily Channel, where recent eruptions of the Ferdinandea Island occurred 20 miles out to sea off Sciacca, has been associated with a clear excess of heat flow. Our results indicate that there is an accumulation of magma below the continental crust of western Sicily that is possibly intruding and out-gassing through roughly N-S trending deep fault systems linked to the mantle, that have an extensional component. Although the identification of these faults is not sufficiently constrained by our data, they could possibly be linked to the pre-existing faults that originated during the Mesozoic extensional-transtensional tectonic phases.
    Description: Published
    Description: L04312
    Description: partially_open
    Keywords: helium isotopes ; heat production ; tectonics ; 03. Hydrosphere::03.04. Chemical and biological::03.04.05. Gases ; 03. Hydrosphere::03.04. Chemical and biological::03.04.06. Hydrothermal systems ; 03. Hydrosphere::03.04. Chemical and biological::03.04.07. Radioactivity and isotopes ; 04. Solid Earth::04.02. Exploration geophysics::04.02.03. Heat flow ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.07. Tectonophysics::04.07.03. Heat generation and transport ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 80
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    Magma dynamics in the shallow plumbing system of Mt. Etna as recorded by compositional variations in volcanics of recent summit activity (1995–1999) (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: We describe the reactivation and the successive evolution of the shallow plumbing system of Mt. Etna between the end of the largest flank eruption of the last three centuries (1991–1993) and the subterminal eruption from South-East Crater (SEC), which occurred between February and mid-November 1999. Our analysis is based on observations of the volcanic activity and petrological studies of the erupted volcanics. Bulk rock, mineral and glass compositions have been determined for more than 80 samples erupted from the four summit craters between October 1995 and February 1999. These data allow us to recognise significant compositional variations among the products of different craters. In particular, volcanics produced between 1995 and 1999 by Bocca Nuova (BN), Voragine (VOR) and North-East Crater (NEC) show limited compositional variations and are similar to those observed during recent eruptions (e.g., 1991–93). More primitive magmas have been produced during the more vigorous fire fountains episodes. On the contrary, the South-East Crater produced slightly more differentiated volcanics than those of the other summit craters following its reactivation (November 1996) until the end of 1998. Whole rock compositions of products from this crater show low CaO/Al2O3, whereas interstitial glasses have lower MgO and higher alkali contents than those from the other craters. However, since the beginning of 1999, and just before the start of the subterminal eruption from SEC, the volcanics erupted from this crater progressively changed in composition, becoming similar to those of the other craters. This trend indicates that within the conduits of the summit craters, distinct thermal and fluid-dynamical regimes can evolve, controlling the cooling and crystallisation of Etna magmas.
    Description: Published
    Description: 55-71
    Description: partially_open
    Keywords: Mount Etna ; crystal fractionation ; petrologic monitoring and magmatic process ; 04. Solid Earth::04.04. Geology::04.04.05. Mineralogy and petrology ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 81
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    Genesis of fumarolic emissions as inferred by isotope mass balances: CO2 and water at Vulcano Island, Italy (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: We have developed a quantitative model of CO2 and H2O isotopic mixing between magmatic and hydrothermal gases for the fumarolic emissions of the La Fossa crater (Vulcano Island, Italy). On the basis of isotope balance equations, the model takes into account the isotope equilibrium between H2O and CO2 and extends the recent model of chemical and energy two-end-member mixing by Nuccio et al. (1999). As a result,the H2O and CO2 content and the dD, d18O, and d13C isotope compositions for both magmatic and hydrothermal end-members have been assessed. Low contributions of meteoric steam, added at a shallow depth, have been also recognized and quantified in the fumaroles throughout the period from 1988 to 1998. Nonequilibrium oxygen isotope exchange also seems to be occurring between ascending gases and wall rocks along some fumarolic conduits. The d13CCO2 of the magmatic gases varies around -3 to 1‰ vs. Peedee belemnite (PDB), following a perfect synchronism with the variations of the CO2 concentration in the magmatic gases. This suggests a process of isotope fractionation because of vapor exsolution caused by magma depressurization. The hydrogen isotopes in the magmatic gases (-1 to -35‰ vs. standard mean ocean water [SMOW]), as well as the above d13CCO2 value, are coherent with a convergent tectonic setting of magma generation, where the local mantle is widely contaminated by fluids released from the subducted slab. Magma contamination in the crust probably amplifies this effect. The computed isotope composition of carbon and hydrogen in the hydrothermal vapors has been used to calculate the dD and d13C of the entire hydrothermal system, including mixed H2O-CO2 vapor, liquid water, and dissolved carbon. We have computed values of about 10‰ vs. SMOW for water and -2 to -6.5‰ vs. PDB for CO2. On these grounds, we think that Mediterranean marine water (dDH2O 10‰) feeds the hydrothermal system. It infiltrates at depth throughout the local rocks, reaching oxygen isotope equilibrium at high temperatures. Interaction processes between magmatic gases and the evolving seawater also seem to occur, causing the dissolution of isotopically fractionated aqueous CO2 and providing the source for hydrothermal carbon. These results have important implications concerning fluid circulation beneath Vulcano and address the more convenient routine of geochemical surveillance.
    Description: Published
    Description: 759–772
    Description: partially_open
    Keywords: isotope geochemistry ; volcanic gases ; mixing modeling ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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