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  • 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics  (10)
  • 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring  (7)
  • 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous  (5)
  • Geological Society of America  (18)
  • AMI
  • American Institute of Physics
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Keywords
Years
  • 1
    Publication Date: 2020-11-26
    Description: Solidified frictional melts, or pseudotachylytes, remain the only unambiguous indicator of seismic slip in the geological record. However, pseudotachylytes form at 〉5 km depth, and there are many rock types in which they do not form at all. We performed low- to high-velocity rock friction experiments designed to impose realistic coseismic slip pulses on calcite fault gouges, and report that localized dynamic recrystallization may be an easy-to-recognize microstructural indicator of seismic slip in shallow, otherwise brittle fault zones. Calcite gouges with starting grain size 〈250 μm were confined up to 26 MPa normal stress using a purpose-built sample holder. Slip velocities were between 0.01 and 3.4 m s−1, and total displacements between 1 and 4 m. At coseismic slip velocities ≥0.1 m s−1, the gouges were cut by reflective principal slip surfaces lined by polygonal grains 〈1 μm in size. The principal slip surfaces were flanked by 〈300 μm thick layers of dynamically recrystallized calcite (grain size 1–10 μm) containing well-defined shape- and crystallographic-preferred orientations. Dynamic recrystallization was accompanied by fault weakening and thermal decomposition of calcite to CO2 + CaO. The recrystallized calcite aggregates resemble those found along the principal slip surface of the Garam thrust, South Korea, exhumed from 〈5 km depth. We suggest that intense frictional heating along the experimental and natural principal slip surfaces resulted in localized dynamic recrystallization, a microstructure that may be diagnostic of seismic slip in the shallow crust.
    Description: Published
    Description: 63-66
    Description: 4T. Fisica dei terremoti e scenari cosismici
    Description: JCR Journal
    Description: reserved
    Keywords: Rock mechanics ; shallow earthquales ; 04. Solid Earth::04.01. Earth Interior::04.01.04. Mineral physics and properties of rocks ; 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::04.07. Tectonophysics::04.07.07. Tectonics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
    Publication Date: 2020-12-21
    Description: Pyroclast textures document volcanic conduit processes and may be key to hazard forecasting. Here we show that the relative abundance of mingled, variably crystallized domains in pyroclasts from scoria cone eruptions provide a record of magma ascent velocity and can be used to predict the onset of violent Strombolian activity. Scoria clasts from the Croscat Complex Scoria Cone (Spain) ubiquitously show m- to cm-sized, microlite-rich domains (MRD) intermingled with volumetrically-dominant, microlite-poor ones (MPD). Glass and bulk composition show that MRDs formed by microlite crystallization of MPDs, the former residing longer in a relatively cooler, degassed zone lining the conduit walls, the latter traveling faster in the central, hotter streamline. MPD and MRD magmas intermingled along the interface between the two velocity zones. The proportion of MPD and MRD in different tephra layers reflects the extent of the fast- and slow-flowing zones, thus reflecting the ascent velocity profile of magma during the different phases. At Croscat, the MPD/MRD volume ratio increased rapidly during the early Strombolian activity, peaked around the Strombolian to violent Strombolian shift, and then decreased smoothly irrespective of shifts in eruptive style. We suggest that magma ascent velocity escalated during the Strombolian phase due to the buoyant push of the underlying, volatile-rich magma that was about to drive the following violent Strombolian activity. Monitoring the MPD/MRD ratio of tephra during ongoing scoria cone eruptions may reveal changes in magma flow conditions and could forecast the onset of hazardous violent Strombolian activity.
    Description: Published
    Description: 439–442
    Description: 2V. Struttura e sistema di alimentazione dei vulcani
    Description: JCR Journal
    Description: open
    Keywords: basaltic ; violent strombolian ; 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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  • 3
    Publication Date: 2021-05-12
    Description: Detecting volcanic unrest is of primary importance for eruption forecasting, especially on volcanoes characterized by highly dangerous, and often seemingly unpredictable, phreatic or phreatomagmatic eruptions. We present a simple and innovative analysis of shallow vertical temperature profiles to depths of 70 cm. These data were recorded at La Fossa cone of Vulcano (Aeolian Islands, Italy), during an episode of increased hydrothermal and seismic activities that occurred between September and December 2009. This work involves the use of the coefficient of determination (R-2) on vertical temperature profiles in order to identify changes in conductive versus convective heat transfer modality. The increase in convective heat transfer can be related to the disruption of the hydrothermal system due to its pressurization and/or variation of ground permeability between the hydrothermal system and the surface. While raw temperature data do not evidence any significant variation during the period investigated and the classic temperature gradient is highly influenced by seasonal variations, the fluctuation of R-2 displayed striking spikes that coincided with the seismic swarm inside the volcanic edifice. Such a low-cost device associated with easy real-time data processing could constitute a very promising, yet deceptively simple, technique to monitor hydrothermal systems, in order to assess the hazard posed by high-energy eruptions for populations living close to active volcanoes.
    Description: Published
    Description: 959-962
    Description: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Description: JCR Journal
    Description: restricted
    Keywords: seismicity ; temperature ; 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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  • 4
    Publication Date: 2021-05-17
    Description: Earthquakes occur along faults in response to plate tectonic movements, but paradoxically, are not widely recognized in the geological record, severely limiting our knowledge of earthquake physics and hampering accurate assessments of seismic hazard. Light-reflective (so-called mirror like) fault surfaces are widely observed geological features, especially in carbonate-bearing rocks of the shallow crust. Here we report on the occurrence of mirror-like fault surfaces cutting dolostone gouges in the Italian Alps. Using friction experiments, we demonstrate that the mirror-like surfaces develop only at seismic slip rates (∼1 m/s) and for applied normal stresses and sliding displacements consistent with those estimated on the natural faults. Under these experimental conditions, the frictional power density dissipated in the samples is comparable to that estimated for natural earthquakes (1–10 MW/m2). Our results indicate that mirror-like surfaces in dolostone gouges are a signature of seismic faulting, and can be used to estimate power dissipation during ancient earthquake ruptures.
    Description: Published
    Description: 1175-1178
    Description: 4T. Fisica dei terremoti e scenari cosismici
    Description: JCR Journal
    Description: reserved
    Keywords: Earthquakes ; Faults ; Carbonates ; Rock Mechanics ; 04. Solid Earth::04.01. Earth Interior::04.01.04. Mineral physics and properties of rocks ; 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
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 5
    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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  • 6
    Publication Date: 2017-04-03
    Description: In September 2002, a series of tectonic earthquakes occurred north of Sicily, Italy, followed by three events of volcanic unrest within 150 km. On October 28, 2002, Mt. Etna erupted; on November 3, 2002, submarine degassing occurred near Panarea Island; and on December 28, 2002, Stromboli Island erupted. All of these events were considered unusual: the Mt. Etna NE-rift eruption was the largest in 55 yr, the Panarea degassing was one of the strongest ever detected there, and the Stromboli eruption, which produced a landslide and tsunami, was the largest effusive eruption in 17 yr. Here, we investigate the synchronous occurrence of these clustered unrest events, and develop a possible explanatory model. We compute short-term earthquake-induced dynamic strain changes and compare them to long-term tectonic effects. Results suggest that the earthquake-induced strain changes exceeded annual tectonic strains by at least an order of magnitude. This agitation occurred in seconds, and may have induced fluid and gas pressure migration within the already active hydrothermal and magmatic systems.
    Description: In press
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.1. Fisica dei terremoti
    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: JCR Journal
    Description: open
    Keywords: earthquake trigger ; magma and gas eruptions ; 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::04.04. 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::04.06.04. 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::04.07.04. 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::04.08.03. 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
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 7
    Publication Date: 2017-04-04
    Description: Strombolian and fire fountain activities represent a common expression of explosive basaltic eruptions. However, the transition between these two eruptive styles and their source mechanisms are still debated. We use textural and compositional studies to characterize pyroclastic material from both the Strombolian and Hawaiian-style fire fountain phases of the January–June 2000 Etna activity. We find that basaltic scoria presents distinctive textural and compositional features that reflect different modes of magma vesiculation and crystallization in the two eruptive regimes. Overall, magma that forms Strombolian scoria is far more crystallized, less vesicular, and more evolved, indicating strong volatile depletion and longer residence time before being erupted. Fire fountain scoria indicates a fast-rising magma with evidence of moderate syneruptive volatile exsolution. The new textural and compositional data set is integrated with previous volcanological and geophysical investigations to provide further insights into the dynamics of fire fountains, and to frame the transition from Strombolian explosions to fire fountain activity into a model that may apply to future eruptions at Mount Etna as well as other active basaltic volcanoes.
    Description: Published
    Description: 201-204
    Description: reserved
    Keywords: Mt. Etna ; explosive activity ; scoria ; textures ; glass compositions ; eruption dynamics ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
    Format: 358707 bytes
    Format: application/pdf
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  • 8
    Publication Date: 2017-04-04
    Description: The spatial clustering of vents in basaltic volcanic fi elds within a stretched continental crust is here used as a proxy for crustal thickness. Basaltic monogenetic vents show self-similar clustering with a power-law distribution defi ned by the correlation exponent (D) computed in a range with lower and upper cutoffs. The upper cutoff for the fractal clustering of vents yields the thickness of the crust. The spatial distribution of vents is analyzed in the Afar Depression (the northern termination of the East African Rift system in Africa), where the continental crust has thinned considerably. More than 1700 vents were identifi ed and mapped in the Afar region through the use of Landsat ETM+ (enhanced thematic mapper) satellite image mosaics. Vents cluster in seven main groups corresponding to the principal structural features of the Afar Depression. The mapped vents are generally younger than 2 Ma, and most are Holocene age. The Afar vents show self-similar clustering (D = 1.39 ± 0.02) in the ~2–23 km range. The upper cutoff of ~23 km matches well the thickness of the crust in the Afar region as derived from seismic and gravity data (~25 km). The distribution of vents in the Afar Depression is compared with that of vents in the northern Main Ethiopian Rift.
    Description: Published
    Description: 152–162
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: 3.2. Tettonica attiva
    Description: 3.6. Fisica del vulcanismo
    Description: N/A or not JCR
    Description: open
    Keywords: volcanic fields, cone distribution, crustal thickness, rift ; 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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  • 9
    Publication Date: 2017-04-04
    Description: Destruction of human property by lava flow invasion is a significant volcanic hazard at Mount Etna (Italy), where reliable risk maps are important for risk mitigation. We present new high-resolution quantitative risk maps of Mount Etna that are based on lava flow simulations starting from more than 70,000 different potential vents, a probability distribution of vent location, an empirical relationship for the maximum length of lava flows, and a database of buildings. In addition to standard risk maps, which classify areas according to the expected damage at each point, we classify each point of the volcano with respect to the damage that would occur if a vent opened at that point. The resulting maps should help local authorities in making the necessary decisions to deal with ongoing eruptions and to plan long-term land use.
    Description: Published
    Description: 1111-1114
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: reserved
    Keywords: Lava flows ; Volcanic risk ; Mount Etna ; 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
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 10
    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)
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