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  • 04. Solid Earth::04.07. Tectonophysics::04.07.06. Subduction related processes
  • Etna
  • Geological Society of America  (5)
  • Copernicus Publications  (2)
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  • 1
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    Holocene slip rate variability along the Pernicana fault system (Mt. Etna, Italy): Evidence from offset lava flows. (2017)
    Geological Society of America
    Details
    Publication Date: 2022-06-14
    Description: The eastern flank of the Mount Etna stratovolcano is affected by extension and is slowly sliding eastward into the Ionian Sea. The Pernicana fault system forms the border of the northern part of this sliding area. It consists of three E-W–oriented fault sectors that are seismically active and characterized by earthquakes up to 4.7 in magnitude (M) capable of producing ground rupture and damage located mainly along the western and central sectors, and by continuous creep on the eastern sector. A new topographic study of the central sector of the Pernicana fault system shows an overall bell-shaped profile, with maximum scarp height of 35 m in the center of the sector, and two local minima that are probably due to the complex morphological relation between fault scarp and lava flows. We determined the ages of lava flows cut by the Pernicana fault system at 12 sites using cosmogenic 3He and 40Ar/39Ar techniques in order to determine the recent slip history of the fault. From the displacementage relations, we estimate an average throw rate of ~2.5 mm/yr over the last 15 k.y. The slip rate appears to have accelerated during the last 3.5 k.y., with displacement rates of up to ~15 mm/yr, whereas between 3.5 and 15 ka, the throw rate averaged ~1 mm/yr. This increase in slip rate resulted in significant changes in seismicity rates, for instance, decreasing the mean recurrence time of M ≥ 4.7 earthquakes from ~200 to ~20 yr. Based on empirical relationships, we attribute the variation in seismic activity on the Pernicana fault system to factors intrinsic to the system that are likely related to changes in the volcanic system. These internal factors could be fault interdependencies (such as those across the Taupo Rift, New Zealand) or they could represent interactions among magmatic, tectonic, and gravitational processes (e.g., Kīlauea volcano, Hawaii). Given their effect on earthquake recurrence intervals, these interactions need to be fully assessed in seismic hazard evaluations.
    Description: Published
    Description: 304-317
    Description: 1V. Storia e struttura dei sistemi vulcanici
    Description: JCR Journal
    Description: open
    Keywords: Etna ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
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    Rheological control on the dynamics of explosive activity in the 2000 summit eruption of Mt. Etna (2011)
    Copernicus Publications
    Details
    Publication Date: 2021-01-27
    Description: In the period from January to June 2000 Mt. Etna exhibited an exceptional explosive activity characterized by a succession of 64 Strombolian and fire-fountaining episodes from the summit South-East Crater. Textural analysis of the eruptive products reveals that the magma associated with the Strombolian phases had a much larger crystal content (〉55 vol%) with respect to the magma discharged during the fire-fountain phases (~35 vol%). Rheological modelling shows that the crystal-rich magma falls in a region beyond a critical crystal content where small addition of solid particles causes an exponential increase of the effective magma viscosity. When implemented into the modeling of steady magma ascent dynamics (as assumed for the fire-fountain activity), a large crystal content as the one found for products of Strombolian eruption phases results in a one order of magnitude decrease of mass flow-rate, and in the onset of conditions where small heterogeneities in the solid fraction carried by the magma translate into highly unsteady eruption dynamics. We argue that crystallization on top of the magmatic column during the intermediate phases when magma was not discharged favoured conditions corresponding to Strombolian activity, with fire-fountain activity resuming after removal of the highly crystalline top. The numerical simulations also provide a consistent interpretation of the association between fire-fountain activity and emergence of lava flows from the crater flanks.
    Description: Published
    Description: 61-69
    Description: 3.6. Fisica del vulcanismo
    Description: N/A or not JCR
    Description: open
    Keywords: Etna ; explosive activity ; scoria textures ; rheological properties ; 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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    Heat loss measured at a lava channel and its implications for down-channel cooling and rheology (2007)
    Geological Society of America
    Details
    Publication Date: 2017-04-04
    Description: During May 2001 we acquired 2016 thermal images over an ~8-h-long period for a section of active lava channel on Mount Etna (Italy). We used these to extract surface temperature and heat-loss profi les and thereby calculate core cooling rates. Flow surface temperatures declined from ~1070 K at the vent to ~930 K at 70 m. Heat losses were dominated by radiation (5 × 104 W m2) and convection (~104 W/m2). These compare with a heat gain from crystallization of 6 × 103 W/m2. The imbalance between sinks and sources gives core cooling (δT/δx) of ~110 K/km. However, cooling rate per unit distance also depends on fl ow conditions, where we distinguished: (1) unimpeded, high-velocity (~0.2 m/s) fl ow with low δT/δx (0.3 K/m); (2) unimpeded, low-velocity (~0.1 m/s) fl ow with higher δT/δx (0.5 K/m); (3) waning, insulated fl ow at low velocity (~0.1 m/s) with low δT/δx (0.3 K/m); and (4) impeded fl ow at low velocity (〈0.1 m/s) with higher δT/δx (0.4 K/m). Our data allow us to defi ne three thermal states of fl ow emplacement: insulated, rapid, and protected. Insulated is promoted by the formation of hanging blockages and coherent roofs. During rapid emplacement, higher velocities suppress cooling rates, and δT/δx can be tied to mean velocity (Vmean) by δT/δx = aVmean –b. In the protected case, deeper, narrow channels present a thermally effi cient channel, where δT/δx can be assessed using the ratio of channel width (w) to depth (d) in w/d = aδT/δx–b.
    Description: Published
    Description: 125-146
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: reserved
    Keywords: lava channel ; Etna ; heat loss ; cooling ; viscosity ; velocity ; FLIR ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 4
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    Images of a lower-crustal oceanic slab: Direct evidence for tectonic accretion in the Archean western Superior province (2007)
    Geological Society of America
    Details
    Publication Date: 2017-04-04
    Description: The Archean western Superior province in Canada is the type area for proposed Archean plate tectonics. Seismic images from this region provide direct evidence for assembly of the craton by terrane accretion and for a large slab of remnant oceanic crust preserved at the base of the crust. This slab, with inferred garnet amphibolite composition, adds a critical piece of evidence to previous suggestions that Archean subduction was at a shallow angle and that some Neoarchean tonalite-trondhjemite-granodiorite suites, distinct from most modern-day suprasubduction magmas, are melts primarily derived directly from subducted slabs.
    Description: LITHOPROBE, Queen's University, Geological Survey of Canada
    Description: Published
    Description: 997–1000;
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: reserved
    Keywords: Archean ; teconics ; seismic ; subduction ; accretion ; 04. Solid Earth::04.07. Tectonophysics::04.07.01. Continents ; 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::04.07.06. Subduction related processes ; 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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  • 5
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    Deep geometry and rheology of an orogenic wedge developing above a continental subduction zone: Seismological evidence from the northern-central Apennines (Italy) (2009)
    Geological Society of America
    Details
    Publication Date: 2017-04-04
    Description: Data from high-density seismic networks deployed between 2000 and 2007 in the north-central Apennines (Italy) yield unprecedented images of an active orogenic wedge. Earthquake foci from the northern Apennines define a Benioff zone deepening westward from the Adriatic foreland down to ~60 km depth below the chain. The seismicity shows that only the lowermost ~10 km of the Adriatic foreland crust is subducted, whereas the uppermost ~20 km is incorporated into the orogenic wedge. Farther west, an aseismic mantle with markedly negative P-wave-velocity (Vp) anomalies is interpreted as asthenosphere flowing toward an Adriatic slab in retrograde motion. Three crustal layers with different Vp and seismicity characteristics are imaged below the northern Apennines: an uppermost 10-km-thick fast layer affected by extensional faulting, a slow layer with diffuse seismicity down to ~15 km depth, and a lowermost fast and aseismic layer resting directly above the asthenosphere. We interpret the latter layer as having formed by anhydrous crust undergoing granulitization, whereas trapped CO2 (either from the underlying granulites or from the subducting Adriatic crust) is inferred to have been responsible for both low Vp and diffuse seismicity in the middle crust. Trapped CO2 is released along the easternmost normal fault systems breaking the Apennine upper crust, consistent with geochemical and seismotectonic evidence. Compressive earthquakes at 20–25 km depth along the external front suggest offscraping of the subducting foreland crust and show that asthenospheric flow represents the primary source of ongoing shortening along the belt front.
    Description: Published
    Description: 95-104
    Description: 1.1. TTC - Monitoraggio sismico del territorio nazionale
    Description: 3.2. Tettonica attiva
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: N/A or not JCR
    Description: reserved
    Keywords: Northern Apennines ; subduction ; orogenic wedge ; seismology ; 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::04.07.04. Plate boundaries, motion, and tectonics ; 04. Solid Earth::04.07. Tectonophysics::04.07.06. Subduction related processes ; 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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  • 6
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    40 Ar/ 39 Ar radiometric dating to constrain the volcanic stratigraphy: The Mt. Etna methodological case. (2010)
    Geological Society of America
    Details
    Publication Date: 2017-04-04
    Description: Although ~50 radiometric age analyses have been performed on Etna, and there are many historical references, these are not enough to temporally constrain the geo- logical evolution of the volcano. In particular, a new stratigraphic framework based on lithostratigraphic and unconformity-bounded units has pointed out the presence of some stratigraphic uncertainty that can be resolved only with radiometric dating. For this reason, a dating project applying the 40 Ar/ 39 Ar incremental heating technique started in 2002. The results obtained improve our understanding and provide con- straints for Etna’s geological evolution; in addition, they show that the applied tech- nique is very useful for dating young basalts and quantifying the hiatus represented by unconformities, as well as for understanding their meaning.
    Description: Published
    Description: 241-248
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: restricted
    Keywords: Ar/Ar dating ; Etna ; 04. Solid Earth::04.04. Geology::04.04.10. Stratigraphy
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 7
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    Integrating geologic fault data into tsunami hazard studies (2013)
    Copernicus Publications
    Details
    Publication Date: 2017-04-04
    Description: We present the realization of a fault-source data set designed to become the starting point in regional-scale tsunami hazard studies. Our approach focuses on the parametric fault characterization in terms of geometry, kinematics, and assessment of activity rates, and includes a systematic classification in six justification levels of epistemic uncertainty related with the existence and behaviour of fault sources. We set up a case study in the central Mediterranean Sea, an area at the intersection of the European, African, and Aegean plates, characterized by a complex and debated tectonic structure and where several tsunamis occurred in the past. Using tsunami scenarios of maximum wave height due to crustal earthquakes (Mw=7) and subduction earthquakes (Mw=7 and Mw=8), we illustrate first-order consequences of critical choices in addressing the seismogenic and tsunamigenic potentials of fault sources. Although tsunamis generated by Mw=8 earthquakes predictably affect the entire basin, the impact of tsunamis generated by Mw=7 earthquakes on either crustal or subduction fault sources can still be strong at many locales. Such scenarios show how the relative location/orientation of faults with respect to target coastlines coupled with bathymetric features suggest avoiding the preselection of fault sources without addressing their possible impact onto hazard analysis results.
    Description: This work was supported by the EC-Research Framework programme FP7, Seismic Hazard Harmonization in Europe, Grant Agreement No. 226769 and the Flagship Project RITMARE – The Italian Research for the Sea – coordinated by the Italian National Research Council and funded by the Italian Ministry of Education, University and Research within the National Research Program 2011–2013.
    Description: Published
    Description: 1025-1050
    Description: 3.2. Tettonica attiva
    Description: 4.2. TTC - Modelli per la stima della pericolosità sismica a scala nazionale
    Description: JCR Journal
    Description: open
    Keywords: active fault ; tsunami ; tsunamigenic source ; earthquake ; PTHA ; hazard ; epistemic uncertainty ; tectonic moment rate ; 03. Hydrosphere::03.01. General::03.01.01. Analytical and numerical modeling ; 04. Solid Earth::04.04. Geology::04.04.01. Earthquake geology and paleoseismology ; 04. Solid Earth::04.04. Geology::04.04.04. Marine geology ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.06. Seismology::04.06.02. Earthquake interactions and probability ; 04. Solid Earth::04.07. Tectonophysics::04.07.04. Plate boundaries, motion, and tectonics ; 04. Solid Earth::04.07. Tectonophysics::04.07.06. Subduction related processes ; 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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