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Plateaux Romain, Bethoux Nicole, BERGERAT Françoise, Mercier De Lépinay Bernard, . (2014). Volcano-tectonic interactions revealed by inversion of focal mechanisms: stress field insight around and beneath the Vatnajökull ice cap in Iceland
. Frontiers in Earth Science , 2 ( ).
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Giret A., Tourpin S., Marc S., Verdier O. & Cottin J.Y. (2002). Volcanisme de l'Ile des Pingouins, Archipel Crozet, témoin de l'hétérogénéité du manteau fertile au sud de l'Océan Indien. Comptes Rendus de Géoscience, 334, 481–488.
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Hreinsdottir Sigrun, Sigmundsson Freysteinn, Roberts Matthew J, Bjornsson Halldor, Grapenthin Ronni, Arason Pordur, Arnadottir Thora, Holmjarn Josef, Geirsson Halldor, Bennett Richard A, Gudmundsson Magnus T, Oddsson Bjorn, Ofeigsson Benedikt G, Villemin Thierry, Jonsson Thorsteinn, Sturkell Erik, Hoskuldsson Armann, Larsen Gudrun, Thordarson Thor, Oladottir Bergrun Arna, . (2014). Volcanic plume height correlated with magma-pressure change at Grimsvotn Volcano, Iceland
. Nature Geoscience, 7(3), 214–218.
Abstract: Magma flow during volcanic eruptions causes surface deformation that can be used to constrain the location, geometry and internal pressure evolution of the underlying magmatic source1. The height of the volcanic plumes during explosive eruptions also varies with magma flow rate, in a nonlinear way2, 3. In May 2011, an explosive eruption at Grímsvötn Volcano, Iceland, erupted about 0.27 km3 dense-rock equivalent of basaltic magma in an eruption plume that was about 20 km high. Here we use Global Positioning System (GPS) and tilt data, measured before and during the eruption at Grímsvötn Volcano, to show that the rate of pressure change in an underlying magma chamber correlates with the height of the volcanic plume over the course of the eruption. We interpret ground deformation of the volcano, measured by geodesy, to result from a pressure drop within a magma chamber at about 1.7 km depth. We estimate the rate of magma discharge and the associated evolution of the plume height by differentiating the co-eruptive pressure drop with time. The time from the initiation of the pressure drop to the onset of the eruption was about 60 min, with about 25% of the total pressure change preceding the eruption. Near-real-time geodetic observations can thus be useful for both timely eruption warnings and for constraining the evolution of volcanic plumes.
Programme: 316
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GEOFFROY L. (2005). Volcanic passive margins. Comptes Rendus de Géoscience, 337, 1395–1409.
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Basile I., Petit J.R., Touron S., Grousset F.E. & Barkov N.I. (2001). Volcanic layers in Antarctic (Vostok) ice-cores : source identification and atmospheric implications. J. Geophys. Res., 106(d23), 31915–31931.
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Baroni Mélanie, Bard Edouard, Petit Jean-Robert, Magand Olivier, Bourlès Didier, . (2011). Volcanic and solar activity, and atmospheric circulation influences on cosmogenic 10Be fallout at Vostok and Concordia (Antarctica) over the last 60 years
. Geochimica et Cosmochimica Acta, 75(22), 7132–7145.
Abstract: The cosmogenic nuclide beryllium-10 (10Be), recovered from ice cores, is often used to study solar activity on long timescales. However, the 10Be signal is also influenced by factors other than the Sun. To identify and quantify various contributions to the 10Be signal, two Antarctic snow records from the Vostok and Concordia sites spanning the last 60 years were studied at a sub-annual resolution. Three factors that contribute to the 10Be signal were identified. First, a significant period of approximately 11 yr that can be associated with the modulation of 10Be production by solar activity was detected in both records. The solar imprint constitutes 2035% of the variance within the total signal. The 11-yr 10Be snow component was attenuated by a factor of 0.5 and was delayed by 1.4 yr compared to the 10Be production expected within the polar atmosphere. The result could be interpreted as the composite response of a stratospheric 10Be reservoir with an 11-yr modulation that was attenuated and delayed (with respect to 10Be polar production) and to a tropospheric 10Be reservoir with an 11-yr modulation that was not attenuated or delayed. Then, peaks in 10Be concentrations that were 66% and 35% higher than the average concentration were observed during the stratospheric volcanic eruptions of Agung (in 1963) and Pinatubo (in 1991), respectively. In light of these new results, published 10Be ice core records could be reinterpreted because spikes in 10Be concentration appear at the time of several stratospheric events. The data indicate that stratospheric volcanic eruptions can impact 10Be transport and deposition as a result of the roles played by the sedimentation of sulfate aerosols and the formation and rapid settling of polar stratospheric clouds (PSC). Also, an interannual variability of 4 yr was determined in both 10Be records, corresponding to 26% of the variance within the signal at Vostok. As with species of marine origin (sodium), this 4-yr variability is interpreted as a tropospheric modulation. The 4-yr variability could be associated with atmospheric circulation associated with the coupled Southern Ocean oceanatmosphere system. The results presented here, from sites within the high Antarctic plateau, open new possibilities for ice core dating over the last few centuries and for the reconstruction of past solar activity in relation to climate.
Programme: 355
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Geoffroy L., Callot J.P. & Gac S. (2006). Volcanic and sedimentary passive margins: why are they so different?.
Abstract: Congrès Inteernational : Quebec, University of Laval, International Lithosphere Program, “The history of Convergent and Passive Margins in the Polar Realm: Sedimentary and Tectonic Processes, Transitions and Resources”, 18-22/09/2006.
Programme: 290
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S. G. Jennings, C. D. O'Dowd, W. F. Cooke, P. J. Sheridan, H. Cachier
. (1994). Volatility of Elemental Carbon. Geophysical research letters, 21, 1719–1722.
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David Grémillet. (2018). Voir les océans par les yeux des oiseaux marins. Planete conferences,Université de Bretagne Sud, Vannes.
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Mulard, H., Aubin, T., Hatch, S.A., White, J. F., Wagner, R. H. and Danchin É. (2009). Voice variance may signify ongoing divergence among black-legged kittiwake populations. Biol. J. Linn. Soc. Lond., 97, 289–297.
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