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  • Articles  (17)
  • Etna  (12)
  • 04. Solid Earth::04.04. Geology::04.04.03. Geomorphology
  • 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous
  • AGU  (6)
  • MISCELLANEA INGV  (6)
  • Nature Publishing Group  (5)
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  • Articles  (17)
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  • 1
    Publication Date: 2020-12-21
    Description: Explosive events, lava-fountains and effusions frequently characterize eruptive activity at Etna. Consequently, the town of Catania and many local municipalities are potentially exposed to ash fallout and lava flows. Besides volcanic hazard, earthquakes and landslides affect this volcanic region as well. The Task 5.1 of the European project "MED-SUV'' (Grant Agreement n°. 308665) deals with the observation of these threatening phenomena from space and ground and their characterization and understanding. The Task encompasses six subtasks, which focus on and analyze the aforementioned hazards in terms of their characteristics, duration and spatial dimension: • Test cases for significant eruptive events have been defined by the subtask 5.1.1. The time span from 2005 to 2011 was chosen for its wealth of eruptive episodes and their well-documented evolution; • The mapping of eruptive products from satellite data will allow us the improvement of the interpretation and modeling of the mechanisms of cone-forming and lava flow emplacement. This topic is developed in the subtask 5.1.2; • Multidisciplinary experiments are planned in the subtask 5.1.3, and will be carried out at the North­ East Crater in July 2014; • Another important deliverable is given by tools of data mining proposed by the subtask 5.1.4. These tools will be available for the analysis of parameters of whatever nature (e.g., geochemical, geophysical), providing they are processed in numerical format; • The subtask 5.1.5 provides a characterization of the volcanic plume and eruptive products, with an integrated analysis of atmospheric, satellite and ground-based measurements, which play an important role in ash-cloud dispersal models; • The sub 5.1.6 focuses on landslide susceptibility analysis and zoning. The goal will be to highlight the regional distribution of potentially unstable slopes based on a detailed study of the factors responsible for landslides.
    Description: Published
    Description: Nicolosi (Catania), Italy
    Description: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Description: open
    Keywords: Etna ; volcanic activity ; threatening phenomena ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Oral presentation
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  • 2
    Publication Date: 2017-04-04
    Description: We estimate the static stress drop on small exhumed strike-slip faults in the Lake Edison granodiorite of the central Sierra Nevada (California). The subvertical strike-slip faults were exhumed from 4 to 15 km depth and were chosen because they are exposed in outcrop along their entire tip-to-tip lengths of 8–12 m. Slip nucleated on joints and accumulated by crystal-plastic shearing (forming quartz mylonites from early quartz vein filling in joints) and successive brittle faulting (forming epidote-bearing cataclasites). The occurrence of thin, 300 mm wide, pseudotachylytes along some small faults throughout the study area suggests that some, if not all, of the brittle slip on the study area faults may have been seismic. We suggest that the contribution of brittle, cataclastic slip to the total slip along the studied cataclasite-bearing small faults may be estimated by the length of epidote-filled, rhombohedral dilatational jogs (rhombochasms) distributed quasi-periodically along the length of the faults. The interpretation that slip recorded by rhombochasms occurred in single events is based on evidence that (1) epidote crystals are randomly oriented and undeformed within the rhombochasm; (2) cataclasite in principal slip zones does not include clasts of previous cataclasite, and (3) rhombochasm lengths vary systematically along the length of the faults with slip maximum occurring near the fault center, tapering to the fault tips. We thereby constrain both the rupture length and slip. On the basis of these measurements, we calculate stress drops ranging over 90–250 MPa, i.e., one to two orders of magnitude larger than typical seismological estimates for earthquakes, but similar in magnitude to seismological estimates of small (〈M2) earthquakes from the San Andreas Fault Observatory at Depth (SAFOD). The slip events described in the present study occurred along small, deep-seated faults, and, given the calculated stress drops and observations that brittle faults exploited joints sealed by quartz-bearing mylonite, we conclude that these were ‘‘strong’’ faults.
    Description: Published
    Description: B02402
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: reserved
    Keywords: earthquakes ; stress drops ; 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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  • 3
    Publication Date: 2017-04-04
    Description: At the westernmost part of the Corinth Rift (Greece), an area of rapid extension and active normal faulting, geomorphological observations reveal the existence and geometry of an active NW-SE trending coastal fault system, which includes the Aigion fault. We recognize a similar fault pattern on both the coastal range front to the NW of Aigion town and the Holocene fan deltas in front of it. We interpret this as a result of recent migration of faulting to the hanging wall of the fault system. Differences in the geomorphic expression of the constituent faults provide hints on the possible evolution of the fault pattern during this recent migration. A trench excavated across one of the identified coastal fault scarps (on a Holocene fan delta) provides information on the seismic history of the fault system, which includes at least four (possibly six) earthquakes in the past 4000 years. A minimum estimate for the slip rate of the trenched fault is 1.9–2.7 mm/yr. The trench exposed sediments of an uplifted paleolagoon (approximate age 2000 years B.P.), inside which the last two earthquakes formed an underwater monoclinal scarp. Oscillating coastal vertical movements are suggested by the fact that the lagoonal deposits are also uplifted on the trenched fault hanging wall (uplift by offshore faults) and by the abrupt transition from fluvial to lagoonal deposits (subsidence by more landward faults, assuming that extensive coastal sediment failure has not taken place in the specific part of the fan delta, within the time interval of interest). These movements suggest that the proposed migration of activity from the range front faults to those on the fan deltas is probably still ongoing, with activity on both sets of faults.
    Description: Published
    Description: B09302
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: reserved
    Keywords: tectonic geomorphology ; paleoseismology ; normal fault evolution ; coastal uplift ; Aigion fault ; western Corinth Gulf ; Greece ; 04. Solid Earth::04.04. Geology::04.04.01. Earthquake geology and paleoseismology ; 04. Solid Earth::04.04. Geology::04.04.03. Geomorphology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 4
    Publication Date: 2017-04-03
    Description: Episodic tremor and slip (ETS) have been correlated with rupture phenomena in subducting oceanic lithosphere at 30–45 km depth, where high VP/VS ratios, which suggest high-fluid pressures, have been observed. ETS, by accommodating slip in the down-dip portion of the subduction zone, may trigger megathrust earthquakes up-dip in the locked section. During dehydration experiments on serpentinite (typical rock of the oceanic lithosphere) at temperatures found in nature at 30–45 km depth (400– 550 C), we observe seismic signals in the form of acoustic emissions that closely resemble low frequency earthquakes, seismic tremor and regular earthquakes. Our findings support the concept that water released during dehydration reactions increases the pore pressures and can trigger ETS and regular earthquakes by reducing slip resistance. Citation: Burlini, L., G. Di Toro, and P. Meredith (2009), Seismic tremor in subduction zones: Rock physics evidence, Geophys. Res. Lett., 36, L08305, doi:10.1029/2009GL037735.
    Description: Published
    Description: L08305
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: reserved
    Keywords: Non volcanic tremor ; dehydration reactions ; 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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  • 5
    Publication Date: 2017-04-04
    Description: We report systematic spatial variations of fault rocks along non-planar strike-slip faults 11 cross-cutting the Lake Edison Granodiorite, Sierra Nevada, California (Sierran wavy fault) and 12 Lobbia outcrops of the Adamello Batholith in the Italian Alps (Lobbia wavy fault). In the case of 13 the Sierran fault, pseudotachylyte formed at contractional fault bends, where it is found as thin 14 (1-2 mm) fault-parallel veins. Epidote and chlorite developed in the same seismic context as the 15 pseudotachylyte and are especially abundant in extensional fault bends. We argue that the 16 presence of fluids, as illustrated by this example, does not necessarily preclude the development 17 of frictional melt. In the case of the Lobbia fault, pseudotachylyte thickness varies along the 18 length of the fault, but the pseudotachylyte veins thicken and pool in extensional bends. We 19 conduct a quantitative analysis of fault roughness, microcrack distribution, stress, and friction 20 along the Lobbia fault. 21 Numerical modeling results show that opening in extensional bends and localized thermal 22 weakening in contractional bends counteract resistance encountered by fault waviness, resulting 23 in an overall weaker fault than suggested by the corresponding static friction coefficient. The 24 models also predict static stress redistribution around bends in the faults which are consistent 25 with distributions of microcracks, indicating significant elastic and inelastic strain energy is 26 dissipated into the wall rocks due to non-planar fault geometry. Together these observations suggest that damage and energy dissipation occurs along the entire non-planar fault during slip, 28 rather than being confined to the region close to the dynamically propagating crack tip.
    Description: Published
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: open
    Keywords: earthquakes ; rutpure ; 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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  • 6
    Publication Date: 2017-04-04
    Description: The 2001 Etna eruption was characterized by a complex temporal evolution with the opening of seven eruptive fissures, each feeding different lava flows. This work describes a method adopted to obtain the three-dimensional geometry of the whole lava flow field and for the reconstruction, based on topographic data, of the temporal evolution of the largest lava flow emitted from a vent located at 2100 m a.s.l. Preeruption and posteruption Digital Elevation Models (DEM) were extracted from vector contour maps. Comparison of the two DEMs and analysis of posteruption orthophotos allowed us to estimate flow area, thickness, and bulk volume. Additionally, the two-dimensional temporal evolution of the 2100 flow was precisely reconstructed by means of maps compiled during the eruption. These data, together with estimates of flow thickness, allowed us to evaluate emitted lava volumes and in turn the average volumetric flow rates The analysis performed in this paper provided, a total lava bulk volume of 40.1 106 m3 for the whole lava flow field, most of which emitted from the 2100 vent (21.4 106 m3). The derived effusion rate trend shows an initial period of waxing flow followed by a longer period of waning flow. This is in agreement not only with the few available effusion rate measurements performed during the eruption, but also with the theoretical model of Wadge (1981) for the temporal variation in discharge during the tapping of a pressurized source
    Description: Published
    Description: F02029
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: JCR Journal
    Description: reserved
    Keywords: Etna ; 2001 eruption ; three-dimensional mapping ; lava volume ; 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: Two previously unpublished maps were retrieved during historical research concerning the historical activity of Etna depicting the eruption which started in December 1634 and continued until 1636. The two drawings, one of which is in colour and the other in ink and sepia water colour, accompany two reports by Jesuits, who were eye-witnesses to the phenomenon. The description of the volcano and the ongoing lava flows was made independently by the two Jesuits, with the help of expert local guides. These two maps represent the first cartography of active Etna hitherto known of.
    Description: Published
    Description: 2-5
    Description: 3.10. Sismologia storica e archeosismologia
    Description: N/A or not JCR
    Description: open
    Keywords: historical volcanology ; Etna ; Ancient eruption Maps ; 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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  • 8
    Publication Date: 2017-04-04
    Description: Studies of past sea-level markers are commonly used to unveil the tectonic history and seismic behavior of subduction zones. We present new evidence on vertical motions of the Hellenic subduction zone as resulting from a suite of Late Pleistocene - Holocene shorelines in western Crete (Greece). Shoreline ages obtained by AMS radiocarbon dating of seashells, together with the reappraisal of shoreline ages from previous works, testify a long-term uplift rate of 2.5-2.7 mm/y. This average value, however, includes periods in which the vertical motions vary significantly: 2.6-3.2 mm/y subsidence rate from 42 ka to 23 ka, followed by ~7.7 mm/y sustained uplift rate from 23 ka to present. The last ~5 ky shows a relatively slower uplift rate of 3.0-3.3 mm/y, yet slightly higher than the long-term average. A preliminary tectonic model attempts at explaining these up and down motions by across-strike partitioning of fault activity in the subduction zone.
    Description: Published
    Description: 5677
    Description: 2T. Tettonica attiva
    Description: JCR Journal
    Description: restricted
    Keywords: coastal geomorphology ; tectonic rates ; paleoshorelines ; subduction ; Crete ; 04. Solid Earth::04.04. Geology::04.04.03. Geomorphology ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 9
    Publication Date: 2017-04-04
    Description: Continuous monitoring at Mt. Etna volcano usually unveils remarkable changes in geophysical and geochemical parameters before the onset of volcanic activity. However, signals of apparent impending volcanic unrest are sometimes recorded without being followed by any eruption. Based on data acquired by the permanent monitoring networks run by INGV, we present cases of "failed eruptions" at Mt Etna from February to April 2007. In the time span analyzed, there were recurrent seismic unrest episodes in the form of enhancements of the volcanic tremor amplitude, which did not culminate in eruptive activity. To explain the origin of these variations, we propose a multidisciplinary study, in which we analyze plume S02 flux, in­ soil radon and ambient parameters (pressure and temperature), thermal and volcanic tremor data. A pattern classification method based on Kohonen maps and fuzzy clustering sheds further light on changes in volcanic tremor, radon and ambient parameters. Overall, we conclude that the variations observed were the results of episodes of gas pulses and/or rock fracturing. The fluid pressure build up allowed upraise of magma batches that generally failed to reach the surface. Actually, only two "real eruptions" (with short­-lived lava fountains on March 29 and April 10-11) occurred during the studied period. In summary, the application of unsupervised classification techniques to volcanic tremor, radon data and ambient parameters represent a promising tool for the surveillance of active volcanoes.
    Description: Published
    Description: Nicolosi (Catania), Italy
    Description: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Description: open
    Keywords: Etna ; data mining ; seismic data ; thermal data ; SO2 flux ; in-situ Radon measurement ; failed eruption ; 05. General::05.01. Computational geophysics::05.01.02. Cellular automata, fuzzy logic, genetic alghoritms, neural networks
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Poster session
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  • 10
    Publication Date: 2017-04-04
    Description: In this paper, we describe the 1809 eruption of Mt. Etna, Italy, which represents one historical rare case in which it is possible to observe details of the internal structure of the feeder system. This is possible thanks to the presence of two large pit craters located in the middle of the eruptive fracture field that allow studying a section of the shallow feeder system. Along the walls of one of these craters, we analysed well-exposed cross sections of the uppermost 15–20 m of the feeder system and related volcanic products. Here, we describe the structure, morphology and lithology of this portion of the 1809 feeder system, including the host rock which conditioned the propagation of the dyke, and compare the results with other recent eruptions. Finally, we propose the dynamic model of the magma behaviour inside a laterally-propagating feeder dyke, demonstrating how this dynamic triggered important changes in the eruptive style (from effusive/Strombolian to phreatomagmatic) during the same eruption. Our results are also useful for hazard assessment related to the development of flank eruptions, potentially the most hazardous type of eruption from basaltic volcanoes in densely urbanized areas, such as Mt. Etna.
    Description: Published
    Description: 1-11
    Description: 2T. Tettonica attiva
    Description: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Description: 3V. Dinamiche e scenari eruttivi
    Description: 4V. Vulcani e ambiente
    Description: 6A. Monitoraggio ambientale, sicurezza e territorio
    Description: N/A or not JCR
    Description: open
    Keywords: feeder dyke ; basaltic volcanoes ; flank eruptions ; Etna ; volcanic hazards ; sill ; volcanic rift ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 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::04.08.04. Thermodynamics ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 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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