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  • 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks
  • Climate-change ecology
  • Nature Publishing Group  (4)
  • Springer Berlin Heidelberg  (3)
  • MDPI Publishing
  • 1
    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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  • 2
    Publication Date: 2017-04-04
    Description: The volcanic history of each active volcano is assembled through detailed field work that establishes stratigraphic position of the eruption deposits, radiometric ages and study of historical sources. The volcanic history is important for hazard assessment, thus the scientific community must validate the strength of conclusions. Fedele et al. (2011) propose a new reference chronostratigraphic framework for Holocene Phlegrean activity, and discuss the implications for the Campi Flegrei (CF) volcanic history and related volcanic hazards. In particular, the authors propose to amend the previously established Holocene chronostratigraphy of volcanic activity of Campi Flegrei caldera, presented in Di Vito et al. (1999), Orsi et al. (2004), Isaia et al. (2009). The proposed changes of Fedele et al. (2011) are based on new geochronologic data, a calibration of already existing 14C ages, and a stratigraphic survey (Perrotta et al. 2010). However, the new chronological data are limited and pre-existing stratigraphic studies have not been considered, and this yields an eruption chronology that is inconsistent with the actual stratigraphic framework.
    Description: Published
    Description: 293-296
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: JCR Journal
    Description: reserved
    Keywords: vents ; Campi Flegrei ; 04. Solid Earth::04.04. Geology::04.04.10. Stratigraphy ; 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
    Publication Date: 2017-04-04
    Description: In recent decades, geophysical investigations have detected wide magma reservoirs beneath quiescent calderas. However, the discovery of partially melted horizons inside the crust is not sufficient to put constraints on capability of reservoirs to supply cataclysmic eruptions, which strictly depends on the chemical-physical properties of magmas (composition, viscosity, gas content etc.), and thus on their differentiation histories. In this study, by using geochemical, isotopic and textural records of rocks erupted from the high-risk Campi Flegrei caldera, we show that the alkaline magmas have evolved toward a critical state of explosive behaviour over a time span shorter than the repose time of most volcanic systems and that these magmas have risen rapidly toward the surface. Moreover, similar results on the depth and timescale of magma storage were previously obtained for the neighbouring Somma-Vesuvius volcano. This consistency suggests that there might be a unique long-lived magma pool beneath the whole Neapolitan area.
    Description: Published
    Description: article 712
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: 3.6. Fisica del vulcanismo
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: N/A or not JCR
    Description: open
    Keywords: magma ; campi flegrei caldera ; 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 ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 4
    Publication Date: 2017-04-04
    Description: The solidified surface of a lava flow reflects the viscosity of its molten fraction and the crystal content during flow; crystal-poor basaltic lavas produce pahoehoe fields, whereas crystal-rich ones solidify with aa carapaces. At Mount Etna, volcano aa morphologies are very common, whereas pahoehoe lavas are rare. The latter are locally named “cicirara” due to the presence of centimeter-sized plagioclase phenocrysts much more abundant than in aa lavas. The phenocryst content of “cicirara” lavas contrasts with the low viscosity generally associated with pahoehoe morphology. Therefore, to reconcile the discrepancy between textural and volcanic observations, we have studied the most primitive pahoehoe “cicirara” lava sampled until now. Two samples at 0.5 and 1 m from the bottom of the 2- m thick lava flow were investigated on the basis of their mineral compositional variations and textural features, i.e., size frequency and crystal size distribution (CSD). Results coupled with rheological models indicate that only large phenocrysts of plagioclase (〉1 mm) and clinopyroxene have grown before eruption. Thermobarometric models and petrological computations based on the composition of plagioclase and clinopyroxene phenocryst cores highlight that only a small amount (10–15 vol.%) of crystals equilibrated at 12 km of depth. Cumulative size frequency and CSD data also indicate that plagioclase and clinopyroxene phenocryst rims grew heterogeneously and coalesced around their cores at depths 〈1 km, before eruption. In this view, the “cicirara” lava was erupted with a low crystalline content that favoured the formation of its pahoehoe surface; however, crystals with a size 〈1 mm (~75 vol.%) solidified at post-eruptive conditions. Our findings underline that the emplacement of high-viscosity aa or low-viscosity pahoehoe lavas is driven by the degree of undercooling imposed by the volatile exsolution rate in the shallowest portion of the Etnean plumbing system. A slow magma ascent rate promotes significant intratelluric degassing and widespread nucleation; consequently, the viscosity of the suspension significantly increases leading to an aa morphology. In contrast, pahoehoe “cicirara” lavas are associated with a rapid rise to the surface of poorly degassed, undercooled magmas.
    Description: Published
    Description: 703
    Description: 2R. Laboratori sperimentali e analitici
    Description: JCR Journal
    Description: restricted
    Keywords: cicirara lava flow ; 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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  • 5
    Publication Date: 2017-04-04
    Description: Pyroclastic density currents (PDC) related to paroxysmal eruptions have caused a large number of casualties in the recent history of Stromboli. We combine here a critical review of historical chronicles with detailed stratigraphic,textural, and petrographic analyses of PDC deposits emplaced at Stromboli over the last century to unravel the origin of currents, their flow mechanism and the depositional dynamics. We focus on the 1930 PDC as they are well described in historical accounts and because the 1930 eruption stands as the most voluminous and destructive paroxysm of the last 13 centuries. Stromboli PDC deposits are recognizable from their architecture and the great abundance of fresh, well-preserved juvenile material. General deposit features indicate that Stromboli PDC formed due to the syn-eruptive gravitational collapse of hot pyroclasts rapidly accumulated over steep slopes. Flow channelization within the several small valleys cut on the flanks of the volcano can enhance the mobility of PDC, as well as the production of fine particles by abrasion and comminution of hot juvenile fragments, thereby increasing the degree of fluidization. Textural analyses and historical accounts also indicate that PDC can be fast (15–20 m/s) and relatively hot (360–700 °C). PDC can thus flow right down the slopes of the volcano, representing a major hazard. For this reason, they must be adequately taken into account when compiling risk maps and evaluating volcanic hazard on the Island of Stromboli.
    Description: Published
    Description: 827-840
    Description: 1V. Storia e struttura dei sistemi vulcanici
    Description: 3V. Dinamiche e scenari eruttivi
    Description: JCR Journal
    Description: restricted
    Keywords: Stromboli, Pyroclastic density currents, Paroxysms, Basaltic explosive volcanism,Volcanic hazard ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 6
    Publication Date: 2022-05-26
    Description: © The Author(s), 2014. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Scientific Reports 4 (2014): 5024, doi:10.1038/srep05024.
    Description: Climate change is a major threat to global biodiversity. Antarctic ecosystems are no exception. Investigating past species responses to climatic events can distinguish natural from anthropogenic impacts. Climate change produces ‘winners’, species that benefit from these events and ‘losers’, species that decline or become extinct. Using molecular techniques, we assess the demographic history and population structure of Pygoscelis penguins in the Scotia Arc related to climate warming after the Last Glacial Maximum (LGM). All three pygoscelid penguins responded positively to post-LGM warming by expanding from glacial refugia, with those breeding at higher latitudes expanding most. Northern (Pygoscelis papua papua) and Southern (Pygoscelis papua ellsworthii) gentoo sub-species likely diverged during the LGM. Comparing historical responses with the literature on current trends, we see Southern gentoo penguins are responding to current warming as they did during post-LGM warming, expanding their range southwards. Conversely, Adélie and chinstrap penguins are experiencing a ‘reversal of fortunes’ as they are now declining in the Antarctic Peninsula, the opposite of their response to post-LGM warming. This suggests current climate warming has decoupled historic population responses in the Antarctic Peninsula, favoring generalist gentoo penguins as climate change ‘winners’, while Adélie and chinstrap penguins have become climate change ‘losers’.
    Description: We thank the Zoological Society of London, Quark Expeditions, Exodus Travels ltd., Oceanites, the Holly Hill Charitable Trust, the Charities Advisory Trust and an U.S. National Science Foundation (NSF) Office of Polar Programs grant (ANT-0739575) for funding.
    Keywords: Climate-change ecology ; Molecular ecology ; Molecular evolution ; Population genetics
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: application/pdf
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  • 7
    Publication Date: 2022-05-26
    Description: © The Author(s), 2016. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Scientific Reports 6 (2016): 29587, doi:10.1038/srep29587.
    Description: Interactions between climate, fire and CO2 are believed to play a crucial role in controlling the distributions of tropical woodlands and savannas, but our understanding of these processes is limited by the paucity of data from undisturbed tropical ecosystems. Here we use a 28,000-year integrated record of vegetation, climate and fire from West Africa to examine the role of these interactions on tropical ecosystem stability. We find that increased aridity between 28–15 kyr B.P. led to the widespread expansion of tropical grasslands, but that frequent fires and low CO2 played a crucial role in stabilizing these ecosystems, even as humidity changed. This resulted in an unstable ecosystem state, which transitioned abruptly from grassland to woodlands as gradual changes in CO2 and fire shifted the balance in favor of woody plants. Since then, high atmospheric CO2 has stabilized tropical forests by promoting woody plant growth, despite increased aridity. Our results indicate that the interactions between climate, CO2 and fire can make tropical ecosystems more resilient to change, but that these systems are dynamically unstable and potentially susceptible to abrupt shifts between woodland and grassland dominated states in the future.
    Description: This work was supported by NSF grants EAR0601998, EAR0602355, AGS0402010, ATM0401908, ATM0214525, ATM0096232 and AGS1243125 and a Chevron Centennial Fellowship at the University of Texas at Austin awarded to T.M.S.
    Keywords: Climate-change ecology ; Palaeoclimate
    Repository Name: Woods Hole Open Access Server
    Type: Article
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