Author: "Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)" / Topic: [sdu.stu.vo]sciences of the universe [physics]/earth sciences/volcanology - Searchworks@Jio Institute Digital Library Search Results

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Start Over Author "Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)" Topic [sdu.stu.vo]sciences of the universe [physics]/earth sciences/volcanology

64 results on '"Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)"'

1. Grand Sarcoui volcano (Chaîne des Puys, Massif Central, France), a case study for monogenetic trachytic lava domes

Author: Philippe Labazuy, J. Rico, Didier Miallier, Thierry Pilleyre, Lydie-Sarah Gailler, Pierre Boivin, Laboratoire de Physique de Clermont (LPC), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS), Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), and Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS)
Subjects: geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Lava, Geochemistry, Lava dome, Massif, 010502 geochemistry & geophysics, 01 natural sciences, Lapilli, Dome (geology), Geophysics, Volcano, Lava field, Geochemistry and Petrology, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Stratovolcano, ComputingMilieux_MISCELLANEOUS, Seismology, Geology, 0105 earth and related environmental sciences
Abstract: International audience; The Grand Sarcoui is a prominent trachytic volcano of the intraplate Quaternary volcanic field of Chaîne des Puys (Massif Central, France), which fulfills basic requirements for being qualified as monogenetic. Grand Sarcoui looks like a simple axisymmetric lava dome, but close observation reveals a complex and dissymmetric structure and composition. The construction of the dome, about 12.5 ka ago, combined both endogenous and exogenous growth which resulted in variable modes of emplacement and textures of the lava. One of its most interesting features is a large (~ 0.29 106 m2) fan of deposits bearing hummocks and secondary hydro-eruption craters. Cross sections of these deposits demonstrate that they originated from a sector collapse accompanied by a blast-like event. The dome is covered by a thin layer of lapilli and ash, attributed to a delayed summit eruption which occurred about 10.6 ka ago, surprisingly late after its construction. So, this volcano has, at a reduced scale, features that are more usually observed in large composite volcanoes. However, some of these features differ slightly from those that have been documented to date, and they remain partly unexplained. This shows that monogenetic, well preserved, trachytic lava domes, are uncommon and poorly known, unlike rhyolitic, andesitic and dacitic domes. (Elsevier)
Published: 2017

2. Melt inclusion evidence for long term steady-state volcanism at Las Sierras-Masaya volcano, Nicaragua

Author: Pierre-J. Gauthier, Nathalie Vigouroux, Glyn Williams-Jones, Séverine Moune, Jeffrey Zurek, Laboratoire Magmas et Volcans (LMV), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Simon Fraser University (SFU.ca), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement et la société-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), and Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Université Jean Monnet [Saint-Étienne] (UJM)
Subjects: Basalt, geography, geography.geographical_feature_category, Fractional crystallization (geology), Olivine, 010504 meteorology & atmospheric sciences, Geochemistry, engineering.material, 010502 geochemistry & geophysics, 01 natural sciences, Geophysics, Effusive eruption, Volcano, 13. Climate action, Geochemistry and Petrology, [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, engineering, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Caldera, Plagioclase, Geology, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Melt inclusions
Abstract: Las Sierras-Masaya volcanic system is a persistently active basaltic caldera complex in Nicaragua. While there has been almost no juvenile material erupted since 1772, Masaya volcano has been persistently degassing for >150 years. An additional unusual behaviour for the Las Sierras-Masaya volcanic complex is its ability to produce large caldera-forming basaltic Plinian eruptions with the most recent occurring about 1800 years ago. Here we present melt inclusion analyses that provide constraints on the magmatic system over time. Melt inclusions hosted in plagioclase and olivine crystals were analyzed for major, trace and volatile elements (S, Cl, F, H2O). The data supports a consistent parental magmatic source with restricted compositional variability explained by simple fractional crystallization of plagioclase, olivine, clinopyroxene and magnetite at a nearly constant temperature. This broadly agrees with previous whole rock geochemical studies showing that the overall chemical signature of volcanic products at Masaya has remained largely unchanged for ~60,000 years and that both shallow fractionation and degassing processes dominate the whole evolution of the magmatic series. Based on volatile element in melt inclusions and gas composition and flux measurements, we determine the magmatic flux to be ~0.19 km3 yr−1 implying that up to 47 km3 of magma may have degassed since the last effusive eruption. As at other persistently active basaltic volcanoes (e.g., Mt. Etna, Italy; Kilauea, Hawaii, USA), this magmatic flux must involve significant endogenous storage which is likely accommodated by extensional tectonics. However, Masaya volcano differs in its apparent simplicity with respect to its stable chemistry and its fully interconnected magmatic system.
Published: 2019

3. Temporal magma source changes at Gaua volcano, Vanuatu island arc

Author: Hervé Bertrand, Aurélien Beaumais, Laure Dosso, Claude Robin, Gilles Chazot, Domaines Océaniques (LDO), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Observatoire des Sciences de l'Univers-Institut d'écologie et environnement-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Sciences de la Terre (LST), École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement [Lyon] (LGL-TPE), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École normale supérieure - Lyon (ENS Lyon), Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Vergniolle, S. (ed.), Métrich, N. (ed.), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement (LGL-TPE), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), and Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 010504 meteorology & atmospheric sciences, Mantle wedge, Earth science, Geochemistry, Pyroclastic rock, Magma chamber, 010502 geochemistry & geophysics, 01 natural sciences, Vanuatu, Isotopes, Geochemistry and Petrology, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Caldera, 0105 earth and related environmental sciences, anuatu, geography, geography.geographical_feature_category, Partial melting, Subduction, Mantle source, Volcanic rock, Geophysics, Volcano, 13. Climate action, Island arc, Gaua, Geology
Abstract: Gaua Island (also called Santa Maria), from the central part of the Vanuatu arc, consists of a large volcano marked by a caldera that hosts the active Mount Garet summit cone. In this paper, a geochemical study including Sr, Nd, Pb and Hf isotopic compositions of 25 lavas emitted since 1.8 Ma is presented, with a focus on the volcanic products that preceded (old volcanics, main cone and pyroclastic series) and followed (Mount Garet) the caldera forming event. All lavas show an island arc signature with enrichment in LILE and depletion in HFSE. Post-caldera lavas define a medium-K calc-alkaline trend, whereas lavas from the former main cone have high-K calc-alkaline compositions. Compared to the pre-caldera volcanic suite, the Mount Garet lavas have similar Th/Nb (similar to 1.5), Nd-143/Nd-144 (similar to 0.51295) and Hf-176/Hf-177 (similar to 0.28316) ratios, but higher Ba/La (similar to 42 vs. similar to 27) and Sr-87/Sr-86 (0.70417 vs. 0.70405) ratios and lower Ce/Pb (similar to 2.7 vs. similar to 4.6), La/Sm (similar to 2.5 vs. similar to 4.0) and Pb-206/Pb-204 (18.105 vs. 18.176) ratios. High Th/Nb and low Nd and Hf isotopic ratios compared to N-MORB suggest the contribution of similar to 2% of subducted sediment melt to the mantle source of Gaua magmas. Most of the observed differences between pre- and post-caldera lavas can be accounted for by the involvement of at least two portions of the mantle wedge, metasomatized by different slab-derived aqueous fluids. In addition, the lower La/Sm (at a given Nd-143/Nd-144) ratios of Mount Garet lavas suggest a higher degree of partial melting (similar to 10-15%) compared to the pre-caldera lavas (similar to 5%). The Santa Maria Pyroclastic Series (SMPS) eruption probably triggered the caldera collapse, in response to emptying of the magmatic chamber. This event may have allowed new access to the surface for a geochemically distinct batch of magma issued from a separate magma chamber, resulting in the birth and construction of Mount Garet within the caldera. As both magmatic suites were emitted over a very short time, the storage of their parental magmas beneath the volcano is still possible.
Published: 2016

4. The extreme mobility of debris avalanches: A new model of transport mechanism

Author: Vincent Famin, Patrick Bachèlery, Laurent Michon, François-Xavier Le Bourdonnec, Helene Périnotto, Jean-Luc Schneider, Environnements et Paléoenvironnements OCéaniques (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), IRAMAT-Centre de recherche en physique appliquée à l’archéologie (IRAMAT-CRP2A), Institut de Recherches sur les Archéomatériaux (IRAMAT), Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Université Bordeaux Montaigne-Université de Technologie de Belfort-Montbeliard (UTBM)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Université Bordeaux Montaigne-Université de Technologie de Belfort-Montbeliard (UTBM), Laboratoire GéoSciences Réunion (LGSR), Université de La Réunion (UR)-Institut de Physique du Globe de Paris, Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École Pratique des Hautes Études (EPHE), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Université de Technologie de Belfort-Montbeliard (UTBM)-Université d'Orléans (UO)-Université Bordeaux Montaigne (UBM)-Centre National de la Recherche Scientifique (CNRS)-Université de Technologie de Belfort-Montbeliard (UTBM)-Université d'Orléans (UO)-Université Bordeaux Montaigne (UBM)-Centre National de la Recherche Scientifique (CNRS), and Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)
Subjects: geography, geography.geographical_feature_category, Physical model, 010504 meteorology & atmospheric sciences, Elastic energy, 010502 geochemistry & geophysics, 01 natural sciences, Debris, Fractal dimension, Grain size, Matrix (geology), Geophysics, Volcano, 13. Climate action, Space and Planetary Science, Geochemistry and Petrology, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Earth and Planetary Sciences (miscellaneous), Fluidization, Petrology, Geomorphology, Geology, 0105 earth and related environmental sciences
Abstract: International audience; Large rockslide-debris avalanches, resulting from flank collapses that shape volcanoes and mountains on Earth and other object of the solar system, are rapid and dangerous gravity-driven granular flows that travel abnormal distances. During the last 50 years, numerous physical models have been put forward to explain their extreme mobility. The principal models are based on fluidization, lubrication, or dynamic disintegration. However, these processes remain poorly constrained. To identify precisely the transport mechanisms during debris avalanches, we examined morphometric (fractal dimension and circularity), grain size, and exoscopic characteristics of the various types of particles (clasts and matrix) from volcanic debris avalanche deposits of La Réunion Island (Indian Ocean). From these data we demonstrate for the first time that syn-transport dynamic disintegration continuously operates with the increasing runout distance from the source down to a grinding limit of 500 μm. Below this limit, the particle size reduction exclusively results from their attrition by frictional interactions. Consequently, the exceptional mobility of debris avalanches may be explained by the combined effect of elastic energy release during the dynamic disintegration of the larger clasts and frictional reduction within the matrix due to interactions between the finer particles.
Published: 2015

5. Textural evolution ofmagma during the 9.4-ka trachytic explosive eruption at Kilian Volcano, Chaîne des Puys, France

Author: Timothy H. Druitt, Mathieu Colombier, Lucia Gurioli, Didier Miallier, Nicolas Cluzel, Thomas Shea, Pierre Boivin, Laboratoire Magmas et Volcans (LMV), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Department of Geology and Geophysics, SOEST, University of Hawaii, Honolulu, HI 96822, USA, University of Hawaii, Laboratoire de Physique Corpusculaire - Clermont-Ferrand (LPC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), ANR-10-LABX-0006,CLERVOLC,Clermont-Ferrand centre for research on volcanism(2010), ANR-16-IDEX-0001,CAP 20-25,CAP 20-25(2016), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), and Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 010504 meteorology & atmospheric sciences, Population, Pyroclastic rock, Density, 010502 geochemistry & geophysics, 01 natural sciences, Permeability, Impact crater, Geochemistry and Petrology, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Vulcanian explosions, VSD, education, Tephra, Petrology, Geomorphology, 0105 earth and related environmental sciences, education.field_of_study, geography, Connectivity, geography.geographical_feature_category, Vulcanian eruption, Explosive eruption, Volcano, 13. Climate action, Clastic rock, Geology, Dome
Abstract: Co-auteur étranger; International audience; Textural parameters such as density, porosity, poreconnectivity, permeability, and vesicle size distributions ofvesiculated and dense pyroclasts from the 9.4-ka eruption ofKilianVolcano, were quantified to constrain conduit and eruptiveprocesses. The eruption generated a sequence of five verticalexplosions of decreasing intensity, producing pyroclasticdensity currents and tephra fallout. The initial and final phasesof the eruption correspond to the fragmentation of a degassedplug, as suggested by the increase of dense juvenile clasts(bimodal density distributions) as well as non-juvenile clasts,resulting from the reaming of a crater. In contrast, the intermediateeruptive phases were the results ofmore open-conduitconditions (unimodal density distributions, decreases in densejuvenile pyroclasts, and non-juvenile clasts). Vesicles withinthe pyroclasts are almost fully connected; however, there are awide range of permeabilities, especially for the dense juvenileclasts. Textural analysis of the juvenile clasts reveals two vesiculationevents: (1) an early nucleation event at lowdecompression rates during slow magma ascent producing apopulation of large bubbles (>1 mm) and (2) a syn-explosivenucleation event, followed by growth and coalescence ofsmall bubbles controlled by high decompression rates immediatelyprior to or during explosive fragmentation. The similaritiesin pyroclast textures between the Kilian explosions andthose at Soufrière Hills Volcano on Montserrat, in 1997, implythat eruptive processes in the two systems were rather similarand probably common to vulcanian eruptions in general.
Published: 2017

6. Eruptive chronology of Tungurahua volcano based on new K-Ar ages and geomorphological reconstructions

Author: Bablon, Mathilde, Quidelleur, X., Samaniego, Pablo, Le Pennec, Jean-Luc, Lahitte, Pierre, Liorzou, Céline, Bustillos, Jorge Eduardo, Hidalgo, Silvana, Géoazur (GEOAZUR 7329), Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA), Géosciences Paris Sud (GEOPS), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Domaines Océaniques (LDO), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Observatoire des Sciences de l'Univers-Institut d'écologie et environnement-Centre National de la Recherche Scientifique (CNRS), Facultad de Ingenieria en Geología, Minas, Petroleos y Ambiental [Ecuador], Universidad Central del Ecuador (UCE), instituto Geofísico, Escuela Politécnica Nacional (EPN), Escuela Politecnica Nacional, Centre National de la Recherche Scientifique (CNRS)-Institut d'écologie et environnement-Observatoire des Sciences de l'Univers-Université de Brest (UBO)-Institut national des sciences de l'Univers (INSU - CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud]), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud]), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne (UCA)-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne (UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS), Facultad de Geología, Universidad Central del Ecuador, Casilla 872 A, Quito, Ecuador, Escuela Politécnica Nacional, and Bablon, Mathilde
Subjects: [SDU.STU.GM] Sciences of the Universe [physics]/Earth Sciences/Geomorphology, [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, [SDU.STU.GC] Sciences of the Universe [physics]/Earth Sciences/Geochemistry, [SDU.STU.VO] Sciences of the Universe [physics]/Earth Sciences/Volcanology, [SDU.STU] Sciences of the Universe [physics]/Earth Sciences, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, K-Ar, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Tungurahua volcano, Ecuador, [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology, ComputingMilieux_MISCELLANEOUS
Abstract: International audience
Published: 2017

7. GPR-derived architecture of a lahar-generated fan at Cotopaxi volcano, Ecuador

Author: Susanne Ettinger, Sarah Kruse, Raphaël Paris, Vern Manville, Laboratoire Magmas et Volcans (LMV), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Géographie Physique et Environnementale (GEOLAB), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut Sciences de l'Homme et de la Société (IR SHS UNILIM), Université de Limoges (UNILIM)-Université de Limoges (UNILIM)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA), Institute of Geophysics and Tectonics, School of Earth and Environment, University of Leeds, College of Arts & Sciences, University of South Florida [Tampa] (USF), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Université Clermont Auvergne (UCA)-Institut Sciences de l'Homme et de la Société (IR SHS UNILIM), and Université de Limoges (UNILIM)-Université de Limoges (UNILIM)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 010504 meteorology & atmospheric sciences, Lahar, Pyroclastic rock, Context (language use), 010502 geochemistry & geophysics, 01 natural sciences, Lapilli, Ground penetrating radar, Stratigraphy, Aggradation, Architecture, Ground-penetrating radar, Facies, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Sediment, Ecuador, Volcano, Geomorphology, Geology, 0105 earth and related environmental sciences, Earth-Surface Processes
Abstract: International audience; The internal geometry of volcaniclastic fans produced by aggradation during lahar events is difficult to examine in modern settings because of the frequent lack of three-dimensional exposures. This makes it challenging to (i) reconstruct the spatial and temporal evolution of such fans; and (ii) interpret observed facies stratigraphy in the context of lahar flow dynamics from proximal to distal fan reaches. This research therefore presents the results of a ground penetrating radar (GPR) survey of the Rumipamba fan at the mouth of the Burrohuaycu quebrada on the southwestern flank of Cotopaxi volcano. A survey grid consisting of 50 individual GPR profiles representing a total length of 19.4 km was constructed covering most of the 4-km2 large fan surface. All GPR profiles were collected using a PulseEKKO 100 with a 400 V transmitter. Fan sediments consist of sandy and gravelly lahar deposits, alternating with volcanic fallout including ash and pumice lapilli, at times reworked by fluvial processes. Deposits could be ground-truthed to a depth of ~3 m, whereas GPR penetration depth reaches 15 m. Data interpretation was based on classification into 15 distinct radar facies characterized by the nature of their bounding surfaces and/or internal features, cross-referenced where possible with shallow exposures. Three main facies were identified: parallel, irregular, and clinoform. Erosional contacts were distinguished from aggradational ones (vertical, channel fill, and lateral accretion). Flow parallel versus flow transverse and proximal–distal variations in deposit architecture were featured. The results of this study confirm the existence of two major channel systems in the northern and southern extremities of the fan and the more recent formation of a smaller central fan channel system. Deposit architecture is complex and facies chronologies illustrate that lahars have affected the entire survey area.
Published: 2014

8. Spatio-Temporal Relationships between Fumarolic Activity, Hydrothermal Fluid Circulation and Geophysical Signals at an Arc Volcano in Degassing Unrest: La Soufrière of Guadeloupe (French West Indies)

Author: Allard, Deroussi, Kitou, Dessert, Bonifacie, Le Marchand, Moune, Didier, Moretti, Tamburello, Venugopal, DeChabalier, Rosas-Carbajal, Beauducel, Robert, Komorowski, Le Friant, Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique du Globe de Paris (IPGP), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université de La Réunion (UR)-Université Paris Diderot - Paris 7 (UPD7)-IPG PARIS-Institut national des sciences de l'Univers (INSU - CNRS), Institut de Physique du Globe de Paris, Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique du Globe de Paris (IPG Paris), Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS), Tamburello, G., Moune, S., Allard, P., Venugopal, S., Robert, V., Rosas-Carbajal, M., Deroussi, S., Kitou, G. -T., Didier, T., Komorowski, J. -C., Beauducel, F., De Chabalier, J. -B., Le Marchand, A., Le Friant, A., Bonifacie, M., Dessert, C., and Moretti, R.
Subjects: Hydrothermal ga, 010504 meteorology & atmospheric sciences, Dome, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, volcanic unrest, Fault (geology), 010502 geochemistry & geophysics, 01 natural sciences, Hydrothermal circulation, guadeloupe, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, 14. Life underwater, Electrical resistivity tomography, Petrology, 0105 earth and related environmental sciences, multigas, geography, geography.geographical_feature_category, Andesite, Volcanic ga, lcsh:QE1-996.5, Lava dome, la soufriere, Multiga, Unrest, extensometry, la soufrière, lcsh:Geology, hydrothermal gas, Volcano, 13. Climate action, General Earth and Planetary Sciences, volcanic gas
Abstract: ： Over the past two decades, La Soufri&egrave, re volcano in Guadeloupe has displayed a growing degassing unrest whose actual source mechanism still remains unclear. Based on new measurements of the chemistry and mass flux of fumarolic gas emissions from the volcano, here we reveal spatio-temporal variations in the degassing features that closely relate to the 3D underground circulation of fumarolic fluids, as imaged by electrical resistivity tomography, and to geodetic-seismic signals recorded over the past two decades. Discrete monthly surveys of gas plumes from the various vents on La Soufri&egrave, re lava dome, performed with portable MultiGAS analyzers, reveal important differences in the chemical proportions and fluxes of H2O, CO2, H2S, SO2 and H2, which depend on the vent location with respect to the underground circulation of fluids. In particular, the main central vents, though directly connected to the volcano conduit and preferentially surveyed in past decades, display much higher CO2/SO2 and H2S/SO2 ratios than peripheral gas emissions, reflecting greater SO2 scrubbing in the boiling hydrothermal water at 80&ndash, 100 m depth. Gas fluxes demonstrate an increased bulk degassing of the volcano over the past 10 years, but also a recent spatial shift in fumarolic degassing intensity from the center of the lava dome towards its SE&ndash, NE sector and the Breislack fracture. Such a spatial shift is in agreement with both extensometric and seismic evidence of fault widening in this sector due to slow gravitational sliding of the southern dome sector. Our study thus provides an improved framework to monitor and interpret the evolution of gas emissions from La Soufri&egrave, re in the future and to better forecast hazards from this dangerous andesitic volcano.
Published: 2019

9. L'origine de la roche mise en œuvre pour la construction du temple de Mercure, au sommet du Puy de Dôme, élucidée, et les implications archéologiques

Author: Philippe Labazuy, Didier Miallier, Pierre Boivin, Bertrand Dousteyssier, Pellet, Jeanine, Laboratoire de Physique Corpusculaire - Clermont-Ferrand (LPC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre d'Histoire 'Espaces et Cultures' (CHEC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), and Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS)
Subjects: trachyte, 010506 paleontology, Archeology, [SHS.ARCHEO] Humanities and Social Sciences/Archaeology and Prehistory, [SHS.ARCHEO]Humanities and Social Sciences/Archaeology and Prehistory, 010504 meteorology & atmospheric sciences, Visual Arts and Performing Arts, [SDE.MCG]Environmental Sciences/Global Changes, volcan, temple de Mercure, Puy de dôme, 01 natural sciences, [SDE.MCG] Environmental Sciences/Global Changes, [SDU.STU.VO] Sciences of the Universe [physics]/Earth Sciences/Volcanology, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Classics, 0105 earth and related environmental sciences
Abstract: Le Puy de Dome (Chaine des Puys, Massif-Central francais) est un volcan de forme approximativement tronconique, d’une altitude maximale de 1465 m (figs. 1-2). Il domine son environnement immediat, le plateau des domes, de 400 m env. et la plaine de Clermont Ferrand — siege de la capitale arverne Augustonemetum — de 1100 m en moyenne.1 C’est un sommet isole, visible jusqu’a 80 kilometres. En contrebas sud du culmen, vers 1450 m, les ruines du “sanctuaire de Mercure” s’organisent en terrasses pour occuper une superficie reconnue de l’ordre de 3500 m2. Decouvert et fouille a la fin du XIXe s.,2 cet edifice a fait, au debut des annees 2000, l’objet de nouvelles etudes qui ont permis d’en revoir et preciser la restitution.3 Les ruines visibles aujourd’hui sont celles d’un tres grand monument de la premiere moitie du IIe s. (fig. 3), qui a succede, d’apres les remplois reconnus, a un monument plus petit construit dans la seconde moitie du Ier s. et dont la localisation exacte reste a preciser.4
Published: 2013

10. Investigating the subsurface connection beneath Cerro Negro volcano and the El Hoyo Complex, Nicaragua

Author: Glyn Williams-Jones, Séverine Moune, Swetha Venugopal, Laboratoire Magmas et Volcans (LMV), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), and Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Basalt, Cinder cone, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Volcanic belt, Geochemistry, Massif, 010502 geochemistry & geophysics, 01 natural sciences, Geophysics, Volcano, Geochemistry and Petrology, Mineral redox buffer, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Melt inclusions Magmatic processes Plumbing system Cerro Negro El Hoyo, Tephra, Geology, 0105 earth and related environmental sciences, Melt inclusions
Abstract: International audience; Cerro Negro, the youngest volcano along the Central American Volcanic Belt (CAVB), is a polygenetic cinder cone with relatively frequent basaltic eruptions. The neighbouring El Hoyo complex, of which Las Pilas is the dominant edifice, is a much larger and older complex with milder and less frequent eruptions. Previous studies have suggested a deep link beneath these two closely spaced volcanoes (McKnight, 1995; MacQueen, 2013). Melt inclusions were collected from various tephra samples in order to determine whether a connection exists and to delineate the features of this link. Major, volatile, and trace elemental compositions reveal a distinct geochemical continuum with Cerro Negro defining the primitive endmember and El Hoyo representing the evolved endmember. Magmatic conditions at the time of melt inclusion entrapment were estimated with major and volatile contents: 2.4 kbar and 1170 °C for Cerro Negro melts and 1.3 kbar and 1130 °C for El Hoyo melts with an overall oxygen fugacity at the NNO buffer. Trace element contents are distinct and suggest Cerro Negro magmas fractionally crystallise while El Hoyo magmas are a mix between primitive Cerro Negro melts and residual and evolved El Hoyo magma. Modelling of end member compositions with alphaMELTS confirms the unique nature of El Hoyo magmas as resulting from incremental mixing between Cerro Negro and residual evolved magma at 4 km depth. Combining all available literature data, this study presents a model of the interconnected subsurface plumbing system. This model considers the modern day analogue of the Lemptégy cinder cones in Massif Central, France and incorporates structurally controlled dykes. The main implications of this study are the classification of Cerro Negro as the newest conduit within the El Hoyo Complex as well as the potential re-activation of the El Hoyo edifice.
Published: 2016

11. Mass budget partitioning during explosive eruptions: insights from the 2006 paroxysm of Tungurahua volcano, Ecuador

Author: Bernard, Julien, Eychenne, Julia, Le Pennec, Jean-Luc, Narváez, Diego, Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS), University of Bristol [Bristol], Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Institut de Recherche pour le Développement et la société-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA), ANR-10-LABX-0006,CLERVOLC,Clermont-Ferrand centre for research on volcanism(2010), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement et la société-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Université Jean Monnet [Saint-Étienne] (UJM), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), and Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: volume-to-mass conversion, mass partitioning, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Tungurahua volcano, intermediate andesitic explosive, eruptions, eruptive budgets, eruption size
Abstract: International audience; How and how much the mass of juvenile magma is split between vent-derived tephra, PDC deposits and lavas (i.e., mass partition) is related to eruption dynamics and style. Estimating such mass partitioning budgets may reveal important for hazard evaluation purposes. We calculated the volume of each product emplaced during the August 2006 paroxysmal eruption of Tungurahua volcano (Ecuador) and converted it into masses using high-resolution grainsize, componentry and density data. This data set is one of the first complete descriptions of mass partitioning associated with a VEI 3 andesitic event. The scoria fall deposit, near-vent agglutinate and lava flow include 28, 16 and 12 wt. % of the erupted juvenile mass, respectively. Much (44 wt. %) of the juvenile material fed Pyroclastic Density Currents (i.e., dense flows, dilute surges and co-PDC plumes), highlighting that tephra fall deposits do not depict adequately the size and fragmentation processes of moderate PDC-forming event. The main parameters controlling the mass partitioning are the type of magmatic fragmentation, conditions of magma ascent, and crater area topography. Comparisons of our data set with other PDC-forming eruptions of different style and magma composition suggest that moderate andesitic eruptions are more prone to produce PDCs, in proportions, than any other eruption type. This finding may be explained by the relatively low magmatic fragmentation efficiency of moderate andesitic eruptions. These mass partitioning data reveal important trends that may be critical for hazard assessment, notably at frequently active andesitic edifices.
Published: 2016

12. L’éruption phréatomagmatique du Montchié, chaîne des puys, Massif Central français (13,6 ± 1,0 ka)

Author: Didier Miallier, Pierre Boivin, Thierry Pilleyre, Serge Sanzelle, Laboratoire de Physique Corpusculaire - Clermont-Ferrand (LPC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Magmas et Volcans (LMV), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), and Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: trachy-andésite, trachy-andesite, Montchié, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], [SDE.MCG]Environmental Sciences/Global Changes, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, [SDU.STU.PE]Sciences of the Universe [physics]/Earth Sciences/Petrography, Geology, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], Chaîne des Puys, éruption phréatomagmatique, phreatomagmatic eruption, Earth-Surface Processes
Abstract: D’épais dépôts d’une formation pyroclastique inconnue auparavant ont été repérés sporadiquement au centre de la Chaîne des Puys. Avec une lithologie polygénique, cette formation a un caractère phréatomagmatique. Le magma juvénile est une trachy-andésite (latite) à phénocristaux d’amphibole, pyroxène et feldspath. La datation de ces dépôts par thermoluminescence, en 4 sites distincts, donne un âge moyen de 13,6 ± 1,0 ka. Leur suivi au sol conduit à l’hypothèse que ces pyroclastites sont issues du cratère nord-est du Montchié, volcan cartographié jusqu’à présent en cône strombolien à cratères multiples et magma basaltique sensu lato. La situation stratigraphique de la formation sur le volcan suggère qu’elle appartient à sa dernière phase éruptive, ce qui est corroboré par un relevé LiDAR sur lequel il est possible d’inférer la chronologie relative des différents cratères. Le Montchié est donc un volcan moins simple que le schéma actuellement admis. L’éruption identifiée ici fournit un nouveau jalon dans la construction complexe du centre de la Chaîne des Puys au Pléistocène supérieur. Thick layers of a previously unknown volcanic formation were discovered in various places in the centre of the Chaîne des Puys. The new tephra has a polygenic composition with phreatomagmatic features. The fresh magma is trachy-andesite (latite), with phenocrysts of amphibole, pyroxene and feldspar. The deposits were dated by means of thermoluminescence in 4 distinct places, with a mean age of 13.6 ± 1.0 ka. Mapping the deposits allowed assuming that they were emitted by the north-east crater of Montchié volcano. The latter was previously described as a basaltic strombolian volcano, with several craters. Tephrostratigraphy of the deposits on the Montchié itself suggest that they were ejected at the end of the volcanic activity. This conclusion is corroborated by LiDAR survey data, which enable to infer the relative chronology of the craters. Montchié volcano appears to be less simple than previously assumed. The eruption identified in the present work provides a new milestone for the complex formation of the centre of Chaîne des Puys during the Upper Pleistocene.
Published: 2016

13. Elevated gas flux and trace metal degassing from the 2014-2015 fissure eruption at the Bárðarbunga volcanic system, Iceland

Author: Gauthier, Pierre-Jean, Sigmarsson, Olgeir, Gouhier, Mathieu, Haddadi, Baptiste, Moune, Séverine, Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), ANR-10-LABX-0006,CLERVOLC,Clermont-Ferrand centre for research on volcanism(2010), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), and Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS)
Subjects: [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology
Abstract: International audience; The 2014 Bárðarbunga rifting event in Iceland resulted in a 6-month long eruption at Holuhraun. This eruption was characterized by high lava discharge rate and significant gas emission. The SO2 flux for the first 3 months was measured with satellite sensors and the petrologic method. High-resolution time series of the satellite data give 1200 kg/s that concurs with 1050 kg/s obtained from melt inclusion minus degassed lava sulfur contents scaled to the mass of magma produced. A high-purity gas sample, with elevated S/Cl due to limited chlorine degassing, reveals a similar degassing pattern of trace metals as observed at Kīlauea (Hawai'i) and Erta Ale (Ethiopia). This suggests a common degassing mechanism at mantle plume-related volcanoes. The trace metal fluxes, calculated from trace element to sulfur ratios in the gas sample and scaled to the sulfur dioxide flux, are 1–2 orders of magnitude stronger at Holuhraun than Kīlauea and Erta Ale. In contrast, volcanoes at convergent margins (Etna and Stromboli, Italy) have 1–2 orders of magnitude higher trace element fluxes, most likely caused by abundant chlorine degassing. This emphasizes the importance of metal degassing as chlorine species. Short-lived disequilibria between radon daughters, 210Pb-210Bi-210Po measured in the gas, suggest degassing of a continuously replenished magma batch beneath the eruption site. Earlier and deep degassing phase of carbon dioxide and polonium is inferred from low (210Po/210Pb) in the gas, consistent with magma transfer rate of 0.75 m/s.
Published: 2016

14. Hummocks: how they form and how they evolve in rockslide-debris avalanches

Author: B. van Wyk de Vries, Engielle Mae Paguican, Alfredo Mahar Francisco Lagmay, Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), National Institute of Geological Sciences, University of the Philippines Cebu (UP Cebu), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), and Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Hummocks, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Break-Up, [SDE.MCG]Environmental Sciences/Global Changes, Analog modeling, Landslide, Rockslide, 010502 geochemistry & geophysics, Geotechnical Engineering and Engineering Geology, Breakup, 01 natural sciences, Debris, Horst and graben structures, Large landslides, Volcano, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Cohesion (geology), Avalanche, Shear zone, Geomorphology, Geology, Seismology, 0105 earth and related environmental sciences
Abstract: International audience; Hummocks are topographic features of large landslides and rockslide-debris avalanches common in volcanic settings. We use scaled analog models to study hummock formation and explore their importance in understanding landslide kinematics and dynamics. The models are designed to replicate large-scale volcanic collapses but are relevant also to non-volcanic settings. We characterize hummocks in terms of their evolution, spatial distribution, and internal structure from slide initiation to final arrest. Hummocks initially form by extensional faulting as a landslide begins to move. During motion, individual large blocks develop and spread, creating an initial distribution, with small hummocks at the landslide front and larger ones at the back. As the mass spreads, hummocks can get wider but may decrease in height, break up, or merge to form bigger and long anticlinal hummocks when confined. Hummock size depends on their position in the initial mass, modified by subsequent breakup or coalescence. A hummock has normal faults that flatten into low-angle detachments and merge with a basal shear zone. In areas of transverse movement within a landslide, elongate hummocks develop between strike-slip flower structures. All the model structures are consistent with field observations and suggest a general brittle-slide emplacement for most landslide avalanches. Absence of hummocks and fault-like features in the deposit may imply a more fluidal flow of emplacement or very low cohesion of lithologies. Hummocks can be used as kinematic indicators to indicate landslide evolution and reconstruct initial failures and provide a framework with which to study emplacement dynamics.
Published: 2012

15. Quantitative textural analysis of Vulcanian pyroclasts (Montserrat) using multi-scale X-ray computed microtomography: comparison with results from 2D image analysis

Author: Laurent Arbaret, Alain Burgisser, Karim Kelfoun, Thomas Giachetti, Timothy H. Druitt, Laboratoire Magmas et Volcans (LMV), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Géographie Physique et Environnementale (GEOLAB), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut Sciences de l'Homme et de la Société (IR SHS UNILIM), Université de Limoges (UNILIM)-Université de Limoges (UNILIM)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA), Institut des Sciences de la Terre d'Orléans (ISTO), Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS), ANR-05-CATT-0003,EXPLANT,EXPLANT : Explosivité de domes de lave - approche analytique, expérimentale et numérique - application aux volcans Antillais(2005), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Université Clermont Auvergne (UCA)-Institut Sciences de l'Homme et de la Société (IR SHS UNILIM), Université de Limoges (UNILIM)-Université de Limoges (UNILIM)-Centre National de la Recherche Scientifique (CNRS), Université de Tours-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), and Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC)
Subjects: Soufrière Hills Volcano, Coalescence (physics), Vesicle number density, Multiple image, Montserrat, 010504 meteorology & atmospheric sciences, [SDE.MCG]Environmental Sciences/Global Changes, Vesicle, Pyroclastic rock, Mineralogy, Vesicle size distribution, Coalescence, 010502 geochemistry & geophysics, First order, 01 natural sciences, Geochemistry and Petrology, X ray computed, Pumice, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Vulcanian explosions, Porosity, Geology, X-ray computed microtomography, 0105 earth and related environmental sciences
Abstract: International audience; X-ray computed microtomography (μCT) was carried out on four pyroclasts from the 1997 Vulcanian explosions of Soufrière Hills Volcano, Montserrat. Three-dimensional data from multiple image stacks with different spatial resolutions (0.37, 4-8, and 17.4 μm px−1) were combined to generate size distributions of vesicles, inter-vesicle throats, crystals, and Fe-Ti oxides over a 3.4-860-μm size range, and to compare the results with those obtained by 2D image analysis on the same samples. Qualitative textural observations are in good agreement with those made in 2D, but μCT provides better resolution of textural features and spatial relationships. Calculation of size distributions requires automated decoalescence of the connected vesicle network. Problems related to this process, in part due to the high porosity of pumice, result in potential artefacts in the calculated size distributions, which are discussed in detail. The main modes of the 3D vesicle volume distributions are systematically shifted to larger sizes compared with those of the 2D distributions. Sample total vesicularities obtained in 3D are within 13 vol.% of those found in 2D, and within 10 vol.% of those measured by He-pycnometry. Total number densities of vesicles and Fe-Ti oxides from the two methods are consistent only to the first order, 3D values ranging from 37% to 309% of those in 2D. Vesicle coalescence, investigated by examining inter-vesicle throat size distributions, occurred in all pyroclasts between neighbouring vesicles of many sizes. The larger the vesicle, the more connected it is.
Published: 2011

16. Bubble nucleation, growth and coalescence during the 1997 Vulcanian explosions of Soufrière Hills Volcano, Montserrat

Author: Timothy H. Druitt, C. Galven, Thomas Giachetti, Alain Burgisser, Laurent Arbaret, Laboratoire Magmas et Volcans (LMV), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Géographie Physique et Environnementale (GEOLAB), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut Sciences de l'Homme et de la Société (IR SHS UNILIM), Université de Limoges (UNILIM)-Université de Limoges (UNILIM)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA), Institut des Sciences de la Terre d'Orléans (ISTO), Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des oxydes et fluorures (LdOF ), Le Mans Université (UM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), ANR-05-CATT-0003,EXPLANT,EXPLANT : Explosivité de domes de lave - approche analytique, expérimentale et numérique - application aux volcans Antillais(2005), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Université Clermont Auvergne (UCA)-Institut Sciences de l'Homme et de la Société (IR SHS UNILIM), Université de Limoges (UNILIM)-Université de Limoges (UNILIM)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Université de Tours-Centre National de la Recherche Scientifique (CNRS), and Le Mans Université (UM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)
Subjects: Soufrière Hills, 010504 meteorology & atmospheric sciences, Bubble nucleation, Lava, [SDE.MCG]Environmental Sciences/Global Changes, Population, Mineralogy, Pyroclastic rock, Bubble growth, Coalescence, 010502 geochemistry & geophysics, 01 natural sciences, Amphibole boudinage, Geochemistry and Petrology, Pumice, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Vulcanian explosions, Vesiculation, Petrology, education, 0105 earth and related environmental sciences, geography, education.field_of_study, geography.geographical_feature_category, Volcanic rock, Igneous rock, Geophysics, Volcano, Phenocryst, Geology
Abstract: International audience; Soufrière Hills Volcano had two periods of repetitive Vulcanian activity in 1997. Each explosion discharged the contents of the upper 0.5–2 km of the conduit as pyroclastic flows and fallout: frothy pumices from a deep, gas-rich zone, lava and breadcrust bombs from a degassed lava plug, and dense pumices from a transition zone. Vesicles constitute 1–66 vol.% of breadcrust bombs and 24–79% of pumices, all those larger than a few tens of µm being interconnected. Small vesicles (< few tens of µm) in all pyroclasts are interpreted as having formed syn-explosively, as shown by their presence in breadcrust bombs formed from originally non-vesicular magma. Most large vesicles (> few hundreds of µm) in pumices are interpreted as pre-dating explosion, implying pre-explosive conduit porosities up to 55%. About a sixth of large vesicles in pumices, and all those in breadcrust bombs, are angular voids formed by syn-explosive fracturing of amphibole phenocrysts. An intermediate-sized vesicle population formed by coalescence of the small syn-explosive bubbles. Bubble nucleation took place heterogeneously on titanomagnetite, number densities of which greatly exceed those of vesicles, and growth took place mainly by decompression. Development of pyroclast vesicle textures was controlled by the time interval between the onset of explosion–decompression and surface quench in contact with air. Lava-plug fragments entered the air quickly after fragmentation (not, vert, similar 10 s), so the interiors continued to vesiculate once the rinds had quenched, forming breadcrust bombs. Deeper, gas-rich magma took longer (not, vert, similar 50 s) to reach the surface, and vesiculation of resulting pumice clasts was essentially complete prior to surface quench. This accounts for the absence of breadcrusting on pumice clasts, and for the textural similarity between pyroclastic flow and fallout pumices, despite different thermal histories after leaving the vent. It also allowed syn-explosive coalescence to proceed further in the pumices than in the breadcrust bombs. Uniaxial boudinage of amphibole phenocrysts in pumices implies significant syn-explosive vesiculation even prior to magma fragmentation, probably in a zone of steep pressure gradient beneath the descending fragmentation front. Syn-explosive decompression rates estimated from vesicle number densities (> 0.3–6.5 MPa s− 1) are consistent with those predicted by previously published numerical models.
Published: 2010

17. Formation of the April 2007 caldera collapse at Piton de La Fournaise volcano: Insights from GPS data

Author: Patrick Bachèlery, Aline Peltier, Valérie Cayol, Thomas Staudacher, Observatoire Volcanologique du Piton de la Fournaise (OVPF), Institut de Physique du Globe de Paris, Laboratoire GéoSciences Réunion (LGSR), Université de La Réunion (UR)-Institut de Physique du Globe de Paris, Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique du Globe de Paris (IPG Paris), Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), and Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 010504 meteorology & atmospheric sciences, GPS, [SDE.MCG]Environmental Sciences/Global Changes, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Magma chamber, 010502 geochemistry & geophysics, 01 natural sciences, Impact crater, Geochemistry and Petrology, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, medicine, Caldera, caldera collapse, ComputingMilieux_MISCELLANEOUS, Collapse (medical), 0105 earth and related environmental sciences, geography, geography.geographical_feature_category, numerical modelling, Subsidence, Piton de la Fournaise, Geophysics, Volcano, 13. Climate action, Magma, medicine.symptom, Seismology, Geology, Stoping
Abstract: International audience; On April 5th 2007, a major collapse of the Dolomieu summit crater occurred at Piton de La Fournaise volcano (La Réunion Island). To constrain the origin and the dynamics of the collapse, we modelled continuous GPS displacements preceding and accompanying this event. Our results reveal that the Dolomieu collapse formed by a “piston-like” mechanism, in which the fast draining of the shallow magma reservoir at the beginning of the March 30th–May 1st 2007 eruption caused a gravity-driven downward displacement of its roof. During the five days preceding the collapse, summit deflation was caused by volume change through the fractured rock column above the shallow magma chamber due to the closure of voids or small-scale cavities or the upward stoping and migration of an underground cavity. Since 2000, weakening of the rock column by repeated refilling and draining of the shallow magma chamber favoured its destabilization. On April 5th, 7 h before the onset of the collapse, the deflation source was located at ~ 300 m depth revealing the initiation of the collapse at very shallow depth. The sudden collapse on April 5th was followed by continuous cyclic subsidence until April 6th. Each cycle was characterized by a progressive inward deflation of the summit zone and ended by sudden summit outward displacements caused by stress relaxation following a collapse event. Subsidence of the stoped column in the magma reservoir during the collapse of the crater on April 5th and 6th acted as a piston thus increasing the eruption rate. The collapse occurred in only 24 h by successive events and increased the depth of the Dolomieu crater by 340 m. After April 6th, only minor readjustments of the summit cone occurred with slight summit deflation and small landslides of the caldera walls.
Published: 2009

18. The distal segment of Etna’s 2001 basaltic lava flow

Author: Maria Teresa Pareschi, Andrew J. L. Harris, Francesco Mazzarini, Massimiliano Favalli, Alessandro Fornaciai, Istituto Nazionale di Geofisica e Vulcanologia – Sezione di Pisa (INGV), Istituto Nazionale di Geofisica e Vulcanologia, Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Department of Geology and Geophysics, University of Hawai‘i [Mānoa] (UHM), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), and Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 010504 meteorology & atmospheric sciences, Lava, [SDE.MCG]Environmental Sciences/Global Changes, Flow (psychology), Zone of dispersed flow, 010502 geochemistry & geophysics, 01 natural sciences, LIDAR, Geochemistry and Petrology, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Flow dynamics, Basalt lava, Geomorphology, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Basalt, geography, geography.geographical_feature_category, Flow front, digestive, oral, and skin physiology, Front (oceanography), Channelised lava flow, Volcanic rock, Igneous rock, Volcano, Etna, Geology, Communication channel
Abstract: Etna’s 2001 basaltic lava flow provided a good example of the distal flow segment between the flow front and stable channel, across which the flow evolves from channel-contained to dispersed. This zone was mapped with meter precision using LIDAR data collected during 2004 and 2005. These data, supported by field mapping, show that the flow front comprised eight lobes each 10 to 20 m high. The flow front appears to have advanced not as a single unit, but as a series of lobes moving forward one lobe at a time. Primary lobes were centered on the channel axis and marginal lobes were off-axis. The lobes advanced as breakouts of low-yield-strength lava from the flow core of the stalled flow front. Marginal lobes were abandoned and contributed to marginal levees flanking the transitional channel. For Etna’s 2001 flow, the transitional channel is 140 m wide, 700 m long and fed a 240-m-long zone of dispersed flow; the change from stable to transitional channel occurred at a major reduction in slope. Above this, the stable channel is 5.2 km long, 55 to 105 m wide and bounded by 15- to 25-m-high levees, and the stable channel is located over a previous channel. In a final stage of activity, lava ponding at the break-in-slope that marks the terminus of the stable channel put pressure on the eastern levee, causing it to fail. Liberated lava then fed a final break-out to the east. Similar flow front-features occur at other volcanoes, indicating that similar processes are characteristic of dispersed flow zones.
Published: 2009

19. Sulphur solubility in andesitic to basaltic melts: implications for Hekla volcano

Author: Francois Holtz, Séverine Moune, Roman E. Botcharnikov, Laboratoire Magmas et Volcans (LMV), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), and Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Sulphide, 010504 meteorology & atmospheric sciences, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], [SDE.MCG]Environmental Sciences/Global Changes, Geochemistry, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], engineering.material, 010502 geochemistry & geophysics, 01 natural sciences, chemistry.chemical_compound, Sulphur, Basaltic andesite, Geochemistry and Petrology, Mineral redox buffer, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Pyrrhotite, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Basalt, Hakla volcano, Saturation, Silicate, Geophysics, chemistry, 13. Climate action, Magma, engineering, Igneous differentiation, Experiments, Saturation (chemistry), Geology
Abstract: The solubility of sulphur in sulphide-saturated, H2O-bearing basaltic–andesitic and basaltic melts from Hekla volcano (Iceland) has been determined experimentally at 1,050°C, 300 and 200 MPa, and redox conditions with oxygen fugacity (logfO2) between QFM−1.2 and QFM+1.1 (QFM is a quartz–fayalite–magnetite oxygen buffer) in the systems containing various amounts of S and H2O. The S content of the H2O-rich glasses saturated with pyrrhotite decreases from 2,500 ppm in basalt to 1,500 ppm in basaltic andesite at the investigated conditions. Furthermore, the reduction of water content in the melt at pyrrhotite saturation and fixed T, P and redox conditions leads to a decrease in S concentration from 2,500 to 1,400 ppm for basaltic experiments (for H2O decrease from 7.8 to 1.4 wt%) and from 1,500 to 900 ppm (for H2O decrease from 6.7 to 1.7 wt%) for basaltic andesitic experiments. Our experimental data, combined with silicate melt inclusion investigations and the available models on sulphide saturation in mafic magmas, indicate that the parental basaltic melts of Hekla were not saturated with respect to sulphide. During magmatic differentiation, the S content in the residual melts increased and might have reached sulphide saturation with 2,500 ppm dissolved S. With further magma crystallization, the S concentration in the melt was controlled by the sulphide saturation of the magma, decreasing from ~2,500 to 900 ppm S.
Published: 2008

20. Geochronologic and stratigraphic constraints on canyon incision and Miocene uplift of the Central Andes in Peru

Author: Jean-Claude Thouret, Brad S. Singer, Xifan Zhang, Gerhard Wörner, T. Souriot, Yanni Gunnell, Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de géographie physique : Environnements Quaternaires et Actuels (LGP), Université Paris 1 Panthéon-Sorbonne (UP1)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS), Department of Geology and Geophysics [Madison], University of Wisconsin-Madison, Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), and Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 010504 meteorology & atmospheric sciences, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Pyroclastic rock, Andes, Late Miocene, 010502 geochemistry & geophysics, Clastic wedge, 01 natural sciences, Paleontology, tectonic uplift, Tectonic uplift, argon dating, Geochemistry and Petrology, Peru, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Earth and Planetary Sciences (miscellaneous), Geomorphology, 0105 earth and related environmental sciences, Canyon, geography, Plateau, geography.geographical_feature_category, Landform, 15. Life on land, valley incision, Geophysics, Denudation, Space and Planetary Science, ignimbrites, Geology
Abstract: International audience; The deepest valleys of the Andes have been cut in southern Peru by the Ríos Cotahuasi Ocoña and Colca–Majes. These canyons are Late Miocene landforms based on a new ignimbrite stratigraphy supported by 42 new 40Ar/39Ar age determinations obtained on plateau-forming and valley-filling ignimbrites. Between 19 and 13 Ma, a gently sloping surface bevelling the clastic wedge southeast of the developing mountain front was mantled by widespread ignimbrites. After 13 Ma, this paleosurface was tilted up from 2.2 km a.s.l. at the mountain front to 4.3 km a.s.l. at the base of the Pliocene and Pleistocene volcanoes that crown the southwestern edge of the Altiplano. The canyons incised this topography after 9 Ma, while the dated base of younger ignimbrite valley fills suggests that these canyons had been cut down to near their present depths as early as 3.8 Ma. By 1.4 Ma, however, the canyons had been almost completely refilled by 1.3 km-thick unwelded pyroclastic deposits, which were subsequently eroded. Valley incision since 9 Ma at an average rate of 0.2 mm yr−1 is the response to topographic uplift after 13 Ma combined with increasing runoff due to a wetter climate recorded after 7 Ma. Although long-term aridity generated an imbalance between high long-term uplift rates and low plateau denudation rates, the combination of aridity and volcanism still promoted canyon incision because episodic volcanic fills maintained a cycle of catastrophic debris avalanches and subsequent dam breakouts.
Published: 2007

21. Early Miocene adakite-like volcanism in the Balkuyumcu region, central Anatolia, Turkey: Petrology and geochemistry

Author: Elif Varol, Abidin Temel, Hervé Bellon, Alain Gourgaud, Department of Geological Engineering, Hacettepe University = Hacettepe Üniversitesi, Laboratoire Magmas et Volcans (LMV), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Domaines Océaniques (LDO), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Observatoire des Sciences de l'Univers-Institut d'écologie et environnement-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), and Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Adakite-like, Geochemistry, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Delaminated lower crust, Balkuyumcu, 010502 geochemistry & geophysics, 01 natural sciences, Mantle (geology), [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, 010503 geology, Petrology, 0105 earth and related environmental sciences, Earth-Surface Processes, geography, Fractional crystallization (geology), geography.geographical_feature_category, biology, Andesite, Continental crust, Partial melting, Geology, 15. Life on land, biology.organism_classification, Volcanic rock, Calc-alkaline, 13. Climate action, Adakite, Lower crust, Lile
Abstract: International audience; The Balkuyumcu region, located in the southwestern part of Ankara in the Izmir-Ankara suture zone (central Anatolia, Turkey), consists of basic andesitic, andesitic, dacitic and rhyolitic rocks extruded during the Early Miocene (20–22 Ma) as a result of post-collisional volcanism. Balkuyumcu volcanic rocks can be divided into two groups on the basis of their mineralogy and composition: The basic andesitic (BA) and andesitic, dacitic and rhyolitic (ADR) groups. The ADR and BA group of rocks have adakite-like and calc-alkaline characteristics, respectively. The ADR group has higher SiO2 content, Sr/Y and La/Yb ratios and low MgO, Mg#, Y and Yb contents than the BA group. Both groups have nearly the same Sr, Nd isotopic compositions and display similar normalized multi-element patterns with enrichments in LILE and LREE, depletions in Nb, Ti, Zr, P and a lack of Eu anomalies. Major, trace element and Sr, Nd isotopic data indicate that both groups of rocks were derived from the same source but affected by different magmatic processes during ascent. The adakite-like rocks may have been produced by partial melting of thickened lower continental crust. Fractional crystallization also played a major role in their formation. However, the BA group rocks were derived from partial melting of lower continental crust that was probably delaminated. These rocks appear to have had limited interaction with mantle peridodite during ascent to the surface.
Published: 2007

22. Influence of rainfalls on heat and steam fluxes of fumarolic zones: Six months records along the Ty fault (Soufrière of Guadeloupe, Lesser Antilles)

Author: Damien Gaudin, Aline Peltier, Fabio Di Gangi, Anthony Finizola, Christophe Delacourt, François Beauducel, Elodie Brothelande, Pascal Allemand, Eric Delcher, Istituto Nazionale di Geofisica e Vulcanologia - Sezione di Roma (INGV), Istituto Nazionale di Geofisica e Vulcanologia, Domaines Océaniques (LDO), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Observatoire des Sciences de l'Univers-Institut d'écologie et environnement-Centre National de la Recherche Scientifique (CNRS), Laboratoire GéoSciences Réunion (LGSR), Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris), Institut de Physique du Globe de Paris (IPGP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement (LGL-TPE), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Magmas et Volcans (LMV), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Observatoire Volcanologique du Piton de la Fournaise (OVPF), Institut de Physique du Globe de Paris (IPG Paris), Instituto Nazionale di Geofisica e Vulcanologie Sezione di Palermo, Université de La Réunion (UR)-Institut de Physique du Globe de Paris, Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement [Lyon] (LGL-TPE), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École normale supérieure - Lyon (ENS Lyon), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), and Institut de Physique du Globe de Paris
Subjects: Hydrology, geography, geography.geographical_feature_category, Rainfalls, Atmospheric sciences, Hydrothermal circulation, Permeability, Geophysics, Flux (metallurgy), Thermal conductivity, Fumarolic zone, Volcano, Heat flux, 13. Climate action, Geochemistry and Petrology, Steam flow, Heat transfer, Numerical modeling, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Geothermal gradient, Condenser (heat transfer), Geology
Abstract: International audience; Fumarolic zones are permeable areas where both steam and heat are expelled to the atmosphere. Surface fluxes and flows, which are representative of the intensity of the hydrothermal circulation in depth, can be monitored by thermometers, thermal infrared cameras, spectrometers, or condensers. However, the superficial activity of fumarolic zones can be modified by the meteorological conditions, in particular the rainfalls, which might result in erroneous estimations. From this perspective, we developed a set of physical equations to quantify the effects of rainfalls on the thermal behavior of fumarolic zones. Results were faced to continuous measurements achieved at the Ty fault fumarolic zone (La Soufrière volcano, Guadeloupe, Lesser Antilles) during six months in 2010, using six vertical series of thermometers measuring the heat transfer in the ground and one condenser measuring the rising steam flux. Results demonstrate that in the absence of rainfalls, heat and steam flux reach an equilibrium that is representa tive of the geothermal flux in depth. Conversely, after the rainfalls, the cooling of the ground provokes a deepening of the condensation level. The related soil temperature drop can be estimated by computing the heat required to warm the infiltrated water up to boiling temperature while the recovery rate is directly linked to the geothermal flux. Our observations allow defining in which conditions flux are at steady state, but also to build a first order numer ical model allowing estimating both the physical parameters of the ground (thermal conductivity, precipitation efficiency coefficient and surface flux constant) and the long term thermal behavior of the hydrothermal system. In particular, our results predict that the hydrothermal activity must vanish on the zones where the geothermal flux drops under a certain threshold (60 W/m 2 at La Soufrière). The existence of this limit may have strong implications for the precipitation rate of minerals and the possible reactivation of the fumarolic zones during volcanic crises.
Published: 2015

23. Geological and geotechnical characteristics of recent lahar deposits from El Misti volcano in the city area of Arequipa, South Peru

Author: Claude Bacconnet, Aurélie Talon, Denis Fabre, Kim Martelli, Calixtro Yanqui-Murillo, Jean-Claude Thouret, Juan Antonio Charca-Chura, Carlos Pallares, Domaines Océaniques (LDO), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Observatoire des Sciences de l'Univers-Institut d'écologie et environnement-Centre National de la Recherche Scientifique (CNRS), Géosciences Paris Sud (GEOPS), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Centre d'enseignement Cnam Paris (CNAM Paris), Conservatoire National des Arts et Métiers [CNAM] (CNAM), Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Blaise Pascal - Clermont-Ferrand 2 (UBP), Facultad de Ingeniería Civil, Universidad Michoacana de San Nicolás de Hidalgo (UMICH), Institut Pascal (IP), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-SIGMA Clermont (SIGMA Clermont)-Centre National de la Recherche Scientifique (CNRS), HESAM Université - Communauté d'universités et d'établissements Hautes écoles Sorbonne Arts et métiers université (HESAM)-HESAM Université - Communauté d'universités et d'établissements Hautes écoles Sorbonne Arts et métiers université (HESAM), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), and Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS)
Subjects: geography, geography.geographical_feature_category, Hydrogeology, Outcrop, Lahar, Soil Science, Pyroclastic rock, Geology, Geotechnical Engineering and Engineering Geology, City area, Volcanic rock, Volcano, Debris-flow deposits, El Misti volcano, Architecture, Soil water, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Dynamic penetrometer, Geotechnical engineering, Hyperconcentrated-flow deposits, Geotechnical properties
Abstract: International audience; This study provides geotechnical characteristics of recent lahar deposits on which the city of Arequipa (South Peru) is built. Geological and sedimentological observations point out the existence of three types of lahar deposits in the Arequipa region: fine hyperconcentrated-flow deposits, coarse hyperconcentrated-flow deposits, and debris-flow deposits. The mineral components identified in the three types of lahars show that they are linked to the outcropping volcanic rocks around Arequipa city. Physical measurements (dry density, grain-size distribution, specific surface of the grains based on methylene blue tests) and mechanical tests (in situ dynamic cone penetration soundings, oedometric and Casagrande shear-box tests) were performed on the three main categories of soils. Our results highlight that hyperconcentrated-flow deposits are fine sand- and silt-rich deposits that lack clay particles. Their dry density is low (ρd = 1.25 g/cm3) and their friction angle is high (ϕ = 38°) which contribute to the peculiar dynamics of lahar flows and to their high erosive power. The low apparent density provides a better capacity for the debulking process, whereas the high friction angle takes part in the erosion process. Finally, the geotechnical properties observed here suggest that the high contents in silica pyroclastic particles and the lack of clay or fine particles control the rheological behavior of lahar deposits. We can also consider that the rheological behavior of lahars through time is complex and that existing older lahars can be remobilized by heavy rain or future stream flows and lahars.
Published: 2015

24. The historical (218 ± 14 aBP) explosive eruption of Tutupaca volcano (Southern Peru)

Author: Nélida Manrique, Benjamin van Wyk de Vries, Corentin Chédeville, Lionel Fidel, Olivier Roche, Jersy Mariño, Pablo Samaniego, Patricio Valderrama, Céline Liorzou, Judicaëlle Malnati, Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Observatorio Vulcanológico del INGEMMET (Dirección de Geología Ambiental y Riesgo Geológico), INGEMMET, Dirección de Geología Ambiental y Riesgo GeológicO, Domaines Océaniques (LDO), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Observatoire des Sciences de l'Univers-Institut d'écologie et environnement-Centre National de la Recherche Scientifique (CNRS), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), and Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Volcanic hazards, Historical activity, Explosive eruption, Lateral eruption, Sector collapse, Geochemistry, Pyroclastic rock, Central Andes, Peléan eruption, Effusive eruption, Dense-rock equivalent, Geochemistry and Petrology, Peru, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Pyroclastic fall, Explosive activity, Geology, Seismology, Tutupaca
Abstract: International audience; The little known Tutupaca volcano (17° 01′ S, 70° 21′ W), located at the southern end of the Peruvian arc, is a dacitic dome complex that experienced a large explosive eruption during historical times. Based on historic chronicles and our radiometric data, this eruption occurred 218 ± 14 aBP, probably between 1787 and 1802 AD. This eruption was characterised by a large sector collapse that triggered a small debris avalanche (
Published: 2015

25. Fundamental changes of granular flow dynamics, deposition, and erosion processes at high slope angles: Insights from laboratory experiments

Author: Farin, Maxime, Mangeney, Anne, Roche, Olivier, Institut de Physique du Globe de Paris (IPGP), Centre National de la Recherche Scientifique (CNRS)-Université de La Réunion (UR)-Université Paris Diderot - Paris 7 (UPD7)-IPG PARIS-Institut national des sciences de l'Univers (INSU - CNRS), Numerical Analysis, Geophysics and Ecology (ANGE), Laboratoire Jacques-Louis Lions (LJLL), Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Inria Paris-Rocquencourt, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria), Laboratoire Magmas et Volcans (LMV), Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), and Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: dynamic, avalanche, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, erosion, deposition
Abstract: Entrainment of underlying debris by geophysical flows can significantly increase the flow deposit extent. To study this phenomenon, analog laboratory experiments have been conducted on granular column collapse over an inclined channel with and without an erodible bed made of similar granular material. Results show that for slope angles below a critical value (c), between 10 degrees and 16 degrees, the run out distance r(f) depends only on the initial column height h(0) and is unaffected by the presence of an erodible bed. On steeper slopes, the flow dynamics change fundamentally, with a slow propagation phase developing after flow front deceleration, significantly extending the flow duration. This phase has characteristics similar to those of steady uniform flows. Its duration increases with increasing slope angle, column volume, column inclination with respect to the slope and channel width, decreasing column aspect ratio (height over length), and in the presence of an erodible bed. It is independent, however, of the maximum front velocity. The increase in the duration of the slow propagation phase has a crucial effect on flow dynamics and deposition. Over a rigid bed, the development of this phase leads to run out distances r(f) that depend on both the initial column height h(0) and length r(0). Over an erodible bed, as the duration of the slow propagation phase increases, the duration of bed excavation increases, leading to a greater increase in the run out distance compared with that over a rigid bed (up to 50%). This effect is even more pronounced as bed compaction decreases.
Published: 2014

26. Gas and aerosol emissions from Lascar volcano (Northern Chile): Insights into the origin of gases and their links with the volcanic activity

Author: Rodrigo Stumpf González, Felipe Aguilera, M. Bontemps, Séverine Moune, Sébastien Valade, Ivan Vlastélic, Gabrielle Menard, Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Departamento de Geología, Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP), Departamento de Ciencias Geológicas, universidad catolica del Norte, Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), and Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: event.disaster_type, Aerosols, Volatiles, geography, Trace elements, geography.geographical_feature_category, Earth science, Trace element, Aquifer, Hydrothermal circulation, Aerosol, Volcanic plume, Volcanic Gases, Atmosphere, Geophysics, Flux (metallurgy), Volcano, 13. Climate action, Geochemistry and Petrology, [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, event, Acid gases, Lascar volcano, Geology
Abstract: International audience; This study focuses on the chemical compositions of volcanic gases and aerosols emitted by Lascar volcano (Northern Chile). The sustained volcanic plume was sampled in April 2009, April 2011 and November 2012 through filter packs and analyzed for major gaseous species (SO2, HCl, and HF) and trace elements. During fieldwork, SO2 flux measurements were also performed by UV spectrometry (DOAS). The Lascar volcano is a significant and sustained emitter of SO2 (between 150 and 940 t/d), HCl (between 170 t/d and 210 t/d) and HF (up to 100 t/d). Combining the SO2-normalized trace element concentrations and the SO2 emission rates, we evaluate that the quiescent degassing of Lascar is an important local source of trace metals to the atmosphere with contributions to global volcanic fluxes generally less than 2%.Our data were used to infer the origin of the gas emitted at Lascar. Two major degassing sources were identified: a deep magmatic reservoir and a shallow hydrothermal system. The variable interaction between these two sources is the most likely scenario for explaining the compositional ranges in acid gases but also in a volatile and fluid–mobile trace element such as B. These variations are related to changes in volcanic activity: an extensive interaction between the hot ascending magmatic gases and the shallow aquifer occurred in 2009, possibly due to a long period of quiescence, before magmatic activity renewed in 2011 and 2012. Our study highlights, therefore, that filter-pack measurements may be used to study changes in subsurface processes that probably play a key role in triggering volcanic eruptions.
Published: 2014

27. Coupling eruption and tsunami records: the Krakatau 1883 case study, Indonesia

Author: Alexander Belousov, Yan Iskandarsyah, Mhammed Benbakkar, Patrick Wassmer, Raphaël Paris, Budianto Ontowirjo, Marina Belousova, Nelly Mazzoni, Franck Lavigne, Laboratoire Magmas et Volcans (LMV), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de géographie physique : Environnements Quaternaires et Actuels (LGP), Université Paris 1 Panthéon-Sorbonne (UP1)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS), Faculté de géographie et d'aménagement, Institute of Volcanology and Seismology of the RAS, Far Eastern Branch of the Russian Academy of Sciences (FEB RAS), Laboratoire Image, Ville, Environnement [Strasbourg] (LIVE), Université de Strasbourg (UNISTRA), BPDP BPPT [Jakarta], BPDP BPPT, Laboratoire de Géographie Physique et Environnementale (GEOLAB), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut Sciences de l'Homme et de la Société (IR SHS UNILIM), Université de Limoges (UNILIM)-Université de Limoges (UNILIM)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Université Clermont Auvergne (UCA)-Institut Sciences de l'Homme et de la Société (IR SHS UNILIM), Université de Limoges (UNILIM)-Université de Limoges (UNILIM)-Centre National de la Recherche Scientifique (CNRS), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), and Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Кракатау (Индонезия), geography, geography.geographical_feature_category, Explosive eruption, Geochemistry, Pyroclastic rock, 38.37.25 Вулканология, Peléan eruption, Lapilli, Volcano, 13. Climate action, Geochemistry and Petrology, Pyroclastic surge, Indonesia, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, 1883 Krakatau eruption, Pyroclastic fall, Geology, Seismology, Volcanic tsunami, Volcanic ash, Tsunami deposits
Abstract: International audience; The well-documented 1883 eruption of Krakatau volcano (Indonesia) offers an opportunity to couple the eruption’s history with the tsunami record. The aim of this paper is not to re-analyse the scenario for the 1883 eruption but to demonstrate that the study of tsunami deposits provides information for reconstructing past eruptions. Indeed, though the characteristics of volcanogenic tsunami deposits are similar to those of other tsunami deposits, they may include juvenile material (e.g. fresh pumice) or be interbedded with distal pyroclastic deposits (ash fall, surges), due to their simultaneity with the eruption. Five kinds of sedimentary and volcanic facies related to the 1883 events were identified along the coasts of Java and Sumatra: (1) bioclastic tsunami sands and (2) pumiceous tsunami sands, deposited respectively before and during the Plinian phase (26–27 August); (3) rounded pumice lapilli reworked by tsunami; (4) pumiceous ash fall deposits and (5) pyroclastic surge deposits (only in Sumatra). The stratigraphic record on the coasts of Java and Sumatra, which agrees particularly well with observations of the 1883 events, is tentatively linked to the proximal stratigraphy of the eruption.
Published: 2014

28. Geology of a volcano selected as a reference experimental site for structure imaging using muography and standard geophysical methods: the Puy de Dôme (Chaîne des Puys, France)

Author: Miallier, Didier, Boivin, Pierre, Labazuy, Philippe, Laboratoire de Physique Corpusculaire - Clermont-Ferrand (LPC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP), Pellet, Jeanine, Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), and Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: [SDE.MCG] Environmental Sciences/Global Changes, volcano, [PHYS.PHYS.PHYS-GEO-PH] Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], muon, [SDE.MCG]Environmental Sciences/Global Changes, [SDU.STU.VO] Sciences of the Universe [physics]/Earth Sciences/Volcanology, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, [SDU.STU.GP] Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], Tomuvol, Puy de Dôme, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph]
Abstract: Since 2010 particle physicists and geoscientists have been collaborating within the ToMuVol project for developing density imaging of volcanoes with atmospheric muons. They have initiated experiences on the Puy de Dôme, a lava-dome located in a small field of quaternary monogenetic volcanoes, Chaîne des Puys in the centre of France. This volcano has a rather simple topography and an appropriate size for applying muon imaging and for comparing this method to standard geophysical survey techniques. Also its inner structure is complex enough for testing the performances and resolution of the different techniques. The Puy de Dôme has been studied for many years. However, recently acquired geophysical data combined with preliminary muon imaging results allowed to refine the structural model of the volcano. The Puy de Dôme close environment offers facilities for housing detectors and it is not far from the Clermont-Ferrand University. These conditions make Puy de Dôme a good candidate for a reference test site. It has already attracted other European groups involved in muon imaging research.
Published: 2013

29. Volcaniclastic sedimentation on the submarine slopes of a basaltic hotspot volcano: Piton de la Fournaise volcano (La Réunion Island, Indian Ocean)

Author: Francky Saint-Ange, Stephan J. Jorry, Laurent Michon, Nathalie Babonneau, Patrick Bachèlery, Geological Survey of Canada [Dartmouth] (GSC Atlantic), Geological Survey of Canada - Office (GSC), Natural Resources Canada (NRCan)-Natural Resources Canada (NRCan), Department of Oceanography [Halifax] (DO), Dalhousie University [Halifax], Laboratoire GéoSciences Réunion (LGSR), Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris), Laboratoire Magmas et Volcans (LMV), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Domaines Océaniques (LDO), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Observatoire des Sciences de l'Univers-Institut d'écologie et environnement-Centre National de la Recherche Scientifique (CNRS), Laboratoire Environnements Sédimentaires (LES), Géosciences Marines (GM), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Ifremer 'sedimentary systems' project (PJ2207), Université de La Réunion (UR)-Institut de Physique du Globe de Paris, Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Environnements Sédimentaires - Géosciences Marines (GM/LES), and Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)
Subjects: landslide, La Réunion Island, 010504 meteorology & atmospheric sciences, [SDE.MCG]Environmental Sciences/Global Changes, Pyroclastic rock, 010502 geochemistry & geophysics, Oceanography, 01 natural sciences, Paleontology, Geochemistry and Petrology, La Reunion Island, Hotspot (geology), [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, 14. Life underwater, [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology, Geomorphology, 0105 earth and related environmental sciences, Basalt, geography, geography.geographical_feature_category, Volcanic arc, debris avalanche, Geology, erosion, volcano, Volcano, 13. Climate action, Subaerial, Facies, Sedimentary rock, turbidites
Abstract: International audience; Volcaniclastic successions are well-described in volcanic arc setting but rare in hotspot environments. The present work proposes a facies model of volcaniclastic sedimentation related to basaltic hotspot volcanoes as exemplified by the Piton de la Fournaise volcano (La Réunion Island). The facies model is based on a multi-scale approach combining high-resolution multibeam and backscatter data, deep-water photographs, side scan imagery and Kullenberg piston cores. Data show that a wide range of gravity flows and erosional features develop in the active volcaniclastic sedimentary system. Coastal and submarine instabilities are the main processes shaping the volcano's submarine morphology. Meanwhile, the evolution and dynamics of the sedimentary system are strongly linked with the morpho-structural evolution of the subaerial part of the volcano. The proposed model is characterized by a cyclic succession of stages: (1) a growing stage during which sedimentary activity is mainly restricted to proximal and mid-slope areas; (2) a collapse stage that entirely reshapes the morphology of the submarine slopes; and (3) an erosional stage related to a slow down of volcanic activity, enabling the development of large deep-sea fans.
Published: 2013

30. The sulfur budget of the 2011 Grímsvötn eruption, Iceland

Author: Kai Yang, Jonas Gudnason, Baptiste Haddadi, Simon Carn, Séverine Moune, Lieven Clarisse, Olgeir Sigmarsson, Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institute of Earth Sciences [Reykjavik], University of Iceland [Reykjavik], Department of Geological and Mining Engineering and Sciences, Michigan Technological University (MTU), Atmospheric Chemistry and Dynamics Branch [ Greenbelt], NASA Goddard Space Flight Center (GSFC), Spectroscopie de l'atmosphère, Service de Chimie Quantique et Photophysique, Université libre de Bruxelles (ULB), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), and Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 010504 meteorology & atmospheric sciences, Sulfide, [SDE.MCG]Environmental Sciences/Global Changes, Geochemistry, chemistry.chemical_element, Mineralogy, engineering.material, 010502 geochemistry & geophysics, 01 natural sciences, sulfur degassing, satellite-based SO2 mass loading, [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, mineral melt inclusions, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Plagioclase, Grímsvötn volcano, Tephra, 0105 earth and related environmental sciences, Melt inclusions, chemistry.chemical_classification, Explosive eruption, Olivine, Sulfur, Geophysics, chemistry, 13. Climate action, Magma, engineering, General Earth and Planetary Sciences, sulfide globules, Geology
Abstract: International audience; Sulfur concentrations have been measured in 28 melt inclusions (MIs) in plagioclase, clinopyroxene, and olivine crystals extracted from tephra produced during the explosive eruption of Grímsvötn in May 2011. The results are compared to sulfur concentrations in the groundmass glass in order to estimate the mass of sulfur brought to surface during the eruption. Satellite measurements yield order of magnitude lower sulfur (~0.2 Tg) in the eruption plume than estimated from the difference between MI and the groundmass glass. This sulfur "deficit" is readily explained by sulfur adhering to tephra grains but principally by sulfide globules caused by basalt-sulfide melt exsolution before degassing. A mass balance calculation reveals that approximately ~0.8 Tg of SO2 is present as globules, representing ~50% of the total sulfur budget. Most of the sulfide globules likely reside at depth due to their elevated density, for potential later remobilization by new magma or hydrothermal circulation.
Published: 2013

31. Structure of Puy de Dôme volcano (Chaîne des Puys, France): towards a revised model

Author: Miallier, Didier, Boivin, Pierre, Deniel, Catherine, Gourgaud, A., Laboratoire de Physique Corpusculaire - Clermont-Ferrand (LPC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), and Pellet, Jeanine
Subjects: [SDE.MCG] Environmental Sciences/Global Changes, volcano, muon, [SDE.MCG]Environmental Sciences/Global Changes, [SDU.STU.VO] Sciences of the Universe [physics]/Earth Sciences/Volcanology, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Tomuvol
Abstract: The project TOMUVOL, aimed at developing a method for muonic tomography of volcanic edifices, has chosen the Puy de Dôme as an experimental test site. In fact, this volcano with a simple external shape has a complex internal structure that may allow testing the performances of this new method. The Puy de Dôme is a composite lava dome, about 11 ka old. It is composed of two distinct morphological units. The first one would consist of a classic bristled lava-dome whereas the second one would be a dome erected on the eastern flank of the first one, after a large flank collapse. However, between 2004 and 2011, fresh outcrops revealed by the building of touristic facilities on the summit and at the basis of the mountain, afforded the collection of new data inducing new questions. The field was then more systematically explored and the results of a LiDAR survey centred on the Puy de Dôme and recorded in March 2011 were examined.
Published: 2012

32. Une éruption importante et méconnue au Montchié (Chaîne des Puys), durant l'Alleröd

Author: Miallier, Didier, Pilleyre, Thierry, Boivin, Pierre, Sanzelle, S., Laboratoire de Physique Corpusculaire - Clermont-Ferrand (LPC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Magmas et Volcans (LMV), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), and Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Massif Central, [SDE.MCG]Environmental Sciences/Global Changes, volcan, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, alleröd, thermoluminescence
Published: 2012

33. Geochemical model of a magmatic-hydrothermal system at the Lastarria volcano, northern Chile

Author: Orlando Vaselli, Felipe Aguilera, Thomas H. Darrah, Séverine Moune, Franco Tassi, Departamento de Geología, Dipartimento di Scienze della Terra [Firenze] (DST), Università degli Studi di Firenze = University of Florence (UniFI), Department of Earth and Environmental Sciences [Rochester], University of Rochester [USA], Department of Environmental, Earth and Ocean Sciences [Boston] (EEOS), University of Massachusetts [Boston] (UMass Boston), University of Massachusetts System (UMASS)-University of Massachusetts System (UMASS), Laboratoire Magmas et Volcans (LMV), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Università degli Studi di Firenze = University of Florence [Firenze] (UNIFI), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), and Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 010504 meteorology & atmospheric sciences, [SDE.MCG]Environmental Sciences/Global Changes, Andean volcanics, Geochemistry, Aquifer, Lastarria volcano, 010502 geochemistry & geophysics, 01 natural sciences, Hydrothermal circulation, Geochemistry and Petrology, Vaporization, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Sedimentology, Sea level, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Hydrology, geography, geography.geographical_feature_category, Liquid layer, Volcano, 13. Climate action, Fumarolic gas, Pressure increase, Ground deformation, Fluid geochemistry, Geology
Abstract: Lastarria volcano (25A degrees 10'aEuro parts per thousand S, 68A degrees 31'aEuro parts per thousand W; 5,697 m above sea level), located in the Central Andes Volcanic Zone (northern Chile), is characterized by four distinct fumarolic fields with outlet temperatures ranging between 80A degrees C and 408A degrees C as measured between May 2006-March 2008 and April-June 2009. Fumarolic gasses contain significant concentrations of high temperature gas compounds (i.e., SO(2), HCl, HF, H(2), and CO), and isotopic ratios ((3)He/(4)He, delta(13)C-CO(2), delta(18)O-H(2)O, and delta D-H(2)O) diagnostic of magmatic gas sources. Gas equilibria systematics, in both the H(2)O-H(2)-CO(2)-CO-CH(4) and alkane-alkene C(3) system, suggest that Lastarria fumarolic gasses emanate from a superheated vapor that is later cooled and condensed at relatively shallow depths. This two-stage process inhibits the formation of a continuous aquifer (e.g., horizontal liquid layer) at relatively shallow depth. Recent developments in the magmatic gas system may have enhanced the transfer and release of heat causing shallow aquifer vaporization. The consequent pressure increase and aquifer vaporization likely triggered the inflation events beginning in 2003 at the Lastarria volcano.
Published: 2012

34. Eyjafjallajökull ash concentrations derived from both lidar and modeling

Author: Chazette, Patrick, Bocquet, Marc, Royer, Philippe, Winiarek, Victor, Raut, Jean-Christophe, Labazuy, Philippe, Gouhier, Mathieu, Lardier, Mélody, Cariou, Jean-Pierre, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Chimie Atmosphérique Expérimentale (CAE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Centre d'Enseignement et de Recherche en Environnement Atmosphérique (CEREA), École des Ponts ParisTech (ENPC)-EDF R&D (EDF R&D), EDF (EDF)-EDF (EDF), Coupling environmental data and simulation models for software integration (Clime), Inria Paris-Rocquencourt, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria), LEOSPHERE France, LEOSPHERE, Centre Alexis Vautrin (CAV), TROPO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Magmas et Volcans (LMV), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), ONERA - The French Aerospace Lab [Châtillon], ONERA-Université Paris Saclay (COmUE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), and Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph], [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Lidar, Ash concentration, Eyjafjallajökull, [SDE.MCG]Environmental Sciences/Global Changes, Modeling, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Volcano
Abstract: International audience; Following the eruption of the Icelandic volcano Eyjafjallajökull on the 14 April 2010, ground-based N2-Raman lidar (GBL) measurements were used to trace the temporal evolution of the ash plume from 16 to 20 April 2010 above the southwestern suburb of Paris. The nighttime overpass of the Cloud-Aerosol LIdar with Orthogonal Polarization onboard Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation satellite (CALIPSO/CALIOP) on 17 April 2010 was an opportunity to complement GBL observations. The plume shape retrieved from GBL has been used to assess the size range of the particles size. The lidar-derived aerosol mass concentrations (PM) have been compared with model-derived PM concentrations held in the Eulerian model Polair3D transport model, driven by a source term inferred from the SEVIRI sensor onboard Meteosat satellite. The consistency between model and ground-based wind lidar and CALIOP observations has been checked. The spatial and temporal structures of the ash plume as estimated by each instrument and by the Polair3D simulations are in agreement. The ash plume was associated with a mean aerosol optical thickness of 0.1{plus minus}0.06 and 0.055{plus minus}0.053 for GBL (355 nm) and CALIOP (532 nm), respectively. Such values correspond to ash mass concentrations of ~400{plus minus}160 and ~720{plus minus}670 µg m-3, respectively, within the ash plume, which was lower than 0.5 km in width. The relative uncertainty is ~75% and mainly due to the assessment of the specific cross-section assuming an aerosol density of 2.6 g cm-3. The simulated ash plume is smoother leading to integrated mass of the same order of magnitude (between 50 and 250 mg m-2)
Published: 2012

35. Decadal to monthly timescales of magma transfer and reservoir growth at a caldera volcano

Author: Fidel Costa, Timothy H. Druitt, Bruno Scaillet, Michael A. Dungan, Etienne Deloule, School of Physical and Mathematical Sciences, Laboratoire Magmas et Volcans (LMV), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS), Earth Observatory of Singapore (EOS), Nanyang Technological University [Singapour], Deépartement de Minéralogie, Université de Genève = University of Geneva (UNIGE), Institut des Sciences de la Terre d'Orléans (ISTO), Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement et la société-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Université Jean Monnet [Saint-Étienne] (UJM), Université de Genève (UNIGE), Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Université de Tours-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), and Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC)
Subjects: Multidisciplinary, Lateral eruption, Vulcanian eruption, Santorini, 010504 meteorology & atmospheric sciences, [SDE.MCG]Environmental Sciences/Global Changes, Geochemistry, Magma chamber, 010502 geochemistry & geophysics, 01 natural sciences, Peléan eruption, Phreatic eruption, Science::Geology::Structural geology [DRNTU], Dense-rock equivalent, Effusive eruption, 13. Climate action, Phreatomagmatic eruption, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, ddc:550, caldera, timescales, Volcanic eruptions, Geology, 0105 earth and related environmental sciences
Abstract: International audience; Caldera-forming volcanic eruptions are low-frequency, highimpact events capable of discharging tens to thousands of cubic kilometres of magma explosively on timescales of hours to days, with devastating effects on local and global scales1. Because no such eruption has been monitored during its long build-up phase, the precursor phenomena are not well understood. Geophysical signals obtained during recent episodes of unrest at calderas such as Yellowstone, USA, and Campi Flegrei, Italy, are difficult to interpret, and the conditions necessary for large eruptions are poorly constrained2,3. Here we present a study of pre-eruptive magmatic processes and their timescales using chemically zoned crystals from the 'Minoan' caldera-formingeruption of Santorini volcano,Greece4, which occurred in the late 1600s BC. The results provide insights into how rapidly large silicic systems may pass from a quiescent state to one on the edge of eruption5,6. Despite the large volume of erupted magma4 (40-60 cubic kilometres), and the 18,000-year gestation period between the Minoan eruption and the previous major eruption, most crystals in the Minoan magma record processes that occurred less than about 100 years before the eruption. Recharge of the magma reservoir by large volumes of silicic magma (and some mafic magma) occurred during the century before eruption, and mixing between different silicicmagmabatches was still taking place during the final months. Final assembly of large silicic magma reservoirs may occur on timescales that are geologically very short by comparison with the preceding repose period, with major growth phases immediately before eruption. These observations have implications for the monitoring of long-dormant, but potentially active, caldera systems.
Published: 2012

36. First estimate of volcanic SO2 budget for Vanuatu island arc

Author: Simon Carn, Clive Oppenheimer, P. Allard, Hiroshi Shinohara, Philipson Bani, Esline Garaebiti, V. I. Tsanev, Michel Lardy, Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD [Nouvelle-Calédonie]), University of Cambridge [UK] (CAM), Institut des Sciences de la Terre d'Orléans (ISTO), Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique du Globe de Paris (IPGP), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS), Institute of Geology and Geoinformation (Geological Survey of Japan), National Institute of Advanced Industrial Science and Technology (AIST), Department of Geological and Mining Engineering and Sciences, Michigan Technological University (MTU), Vanuatu Meteorological and Gehazards Department, Volgaspec projects 2007-2010 from the Fond Pacifique UK Natural Environment Research Council for support via the national centre for earth observation 'Dynamic Earth and gehazards' program., ANR-06-CATT-0002,ARC-VANUATU,Dynamique eruptive et cycle sismique dans l'arc de Vanuatu(2006), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), and Université de Tours-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)
Subjects: geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Lava, Earth science, [SDE.MCG]Environmental Sciences/Global Changes, Gas emissions, 010502 geochemistry & geophysics, 01 natural sciences, Vanuatu volcanoes, Mantle (geology), Tectonics, Geophysics, Volcano, 13. Climate action, Geochemistry and Petrology, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Island arc, Geology, SO2 budget, 0105 earth and related environmental sciences
Abstract: International audience; The spatial and temporal coverage of measurements of previous termvolcanicnext term gas emissions remains patchy. However, over the last decade, emissions inventories have improved thanks to new measurements of some of the lesser-known previous termvolcanicnext term areas. We report on one such region - the Vanuatu island arc, in the Southwest Pacific - for which we now have sufficient systematic observations to offer a systematic emissions inventory. Our new estimate is based on SO2 flux measurements made in the period 2004-2009 with ultraviolet spectroscopy techniques for the following volcanoes: Yasur, Lopevi, Ambrym, Ambae, Gaua and Vanua Lava (from south to north). These are the first ever measurements for Lopevi, Gaua and Vanua Lava. The results reveal the Vanuatu arc as one of Earth's prominent sources of previous termvolcanicnext term degassing with a characteristic annual emission to the atmosphere of ~ 3 Tg of SO2 (representing about 20% of hitherto published global estimates). Our new dataset highlights the sustained prodigious degassing of Ambrym volcano, whose 5 Gg d-1 mean flux of SO2 represents nearly two-thirds of the total budget for the Vanuatu arc. This confirms Ambrym as one of the largest previous termvolcanic sources worldwide comparable to Etna, often considered as the most vigorous source of previous termvolcanic emission on Earth. We also report a high degassing for Ambae of ~ 2 Gg d-1 SO2, representing more than 28 % of the Vanuatu arc budget. Thus, 90 % of the SO2 output from Vanuatu is focused in the central part of the arc (from Ambrym and Ambae) where magmas originate from enriched Indian-type mantle and where peculiar tectonic conditions could favour high magma production rates.
Published: 2012

37. Impact of tephra falls on Andean communities : the influences of eruption size and weather conditions during the 1999-2001 activity of Tungurahua volcano, Ecuador

Author: Jean-Luc Le Pennec, Hugo Yepes, Patricio Ramón, Patricia Mothes, Gorki A. Ruiz, Enrique Palacios, Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), instituto Geofísico, Escuela Politécnica Nacional (EPN), Instituto Nacional de Meteorología e Hidrología (INAMHI), Secretaría Nacional de Gestíon de Riesgos, Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Instituto Geofísico, and Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 010504 meteorology & atmospheric sciences, [SDE.MCG]Environmental Sciences/Global Changes, Hazard analysis, Weather conditions, 010502 geochemistry & geophysics, 01 natural sciences, Settling, Geochemistry and Petrology, Dry season, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Tephra, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Hydrology, geography, geography.geographical_feature_category, Tungurahua volcano, Wind direction, Tephra volume, Plume, Geophysics, Volcano, 13. Climate action, Physical geography, Ash fall, Andean communities, Ecuador, Geology, Volcanic ash
Abstract: Repeated ash fall events have occurred during the 1999-ongoing eruption of Tungurahua volcano, Ecuador, notably during the late 1999 and August 2001 eruptive phases. While the eruptive styles were similar, these two phases had different impacts on nearby rural and urban Andean populations: ash falls in late 1999 had limited effects on human health and farming, whereas the 2001 phase resulted in medical problems, death of animals in livestock, and damages to houses and crops. Here we investigate the origin of this difference by estimating the size of the August 2001 event (VEI, magnitude, intensity), and by comparing monitoring information of the 1999 and 2001 phases (duration, explosion rate, column height, SO2 output rate). The results show that both phases ranked at VEI 3, although the longer 1999 phase was likely larger than the 2001 phase. Mass magnitude (M) and intensity (I) indexes calculated for the 2001 phase reach M approximate to 2.7 and I approximate to 6.5 when based on ash fall layer data, but increase to M approximate to 3.2 and I approximate to 7.0 when ballistic products are included. We investigated the influence of rain fall and wind flow regimes on ash dispersion, sedimentation and remobilization. The analysis indicates that the harmful effect of the 2001 phase resulted from unfavorable conditions that combined volcanological and seasonal origins, including: a) a low elevation of the ash plume above rural regions owed to a usually bent-over column, b) ash sedimentation in a narrow area west of the volcano under sub-steady wind directions, c) anticipated ash settling by frequent rain flushing of low intensity, and d) formation of a wet cohesive ash coating on buildings and harvests. Conversely, the stronger 1999 phase injected a large amount of ash at higher elevation in the dry season; the ash was widely disseminated across the whole Ecuadorian territory and beyond, and was frequently removed by rain and winds. In summary, our study illustrates the influences of eruption size and weather conditions on the impact of volcanic activity in a tropical setting and puts emphasis on the necessity to merge volcanological and meteorological monitoring duties for hazard assessment and alert level definition, in order to mitigate the effect of ash falls in the Andes and elsewhere.
Published: 2012

38. Internal structure and building of basaltic shield volcanoes: the example of the Piton de La Fournaise terminal cone (La Réunion)

Author: Anthony Finizola, Patrick Bachèlery, Aline Peltier, Frédérick Massin, Institut de Physique du Globe de Paris (IPGP), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS), Department of Geology and Geophysics, Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire GéoSciences Réunion (LGSR), Université de La Réunion (UR)-Institut de Physique du Globe de Paris, Observatoire Volcanologique du Piton de la Fournaise (OVPF), Institut de Physique du Globe de Paris, Department of Geology & Geophysics, University of Utah, Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique du Globe de Paris (IPG Paris), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), and Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)
Subjects: Basalt, Lateral eruption, 010504 meteorology & atmospheric sciences, Outcrop, [SDE.MCG]Environmental Sciences/Global Changes, Piton de La Fournaise, Basaltic volcanoes, 010502 geochemistry & geophysics, 01 natural sciences, Volcano lithostratigraphy, Caldera collapse, Paleontology, Shield volcano, Impact crater, 13. Climate action, Geochemistry and Petrology, Magma, Historic records, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Caldera, Sedimentology, Seismology, Geology, 0105 earth and related environmental sciences
Abstract: International audience; In April 2007, a caldera collapsed at the Dolomieu summit crater of Piton de La Fournaise (La Réunion Island, Indian Ocean) revealing new outcrops up to 340 m high along the crater walls. The lithostratigraphic interpretation of these new exposures allows us to investigate the most recent building history of a basaltic shield volcano. We present the history of the Piton de La Fournaise terminal cone, from the building of a juvenile cone during which periods of explosive activity dominated, to the most recent effusive period. The changes in eruptive dynamics are the cause of successive summit crater/ pit–crater collapses. In April 2007, such an event occurred during rapid emptying of the shallow plumbing system feeding a large effusive lateral eruption. During the most recent effusive period, an eastward migration of the eruptive crater was observed and was linked to the successive destructions of the shallow magma reservoir during each collapse. The resulting changes in the local stress field favor the formation of a new reservoir and thus the migration of activity. Internal structures reveal that the building of the upper part of the terminal cone was predominantly by exogenous growth and that the hydrothermal system is confined at a depth >350 m. These observations on Piton de La Fournaise provide new insights into construction of the summits of other basaltic shield volcanoes.
Published: 2012

39. Le point sur l’éruption du lac Pavin, il y a 7 000 ans

Author: Boivin, Pierre, Ferry, P., Besson, J.C., Gourgaud, Alain, Miallier, Didier, Thouret, Jean-Claude, Vernet, Gérard, Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Departement des Sciences de la Terre, Ecole Nationale Superieure de Lyon, Laboratoire de Physique Corpusculaire - Clermont-Ferrand (LPC), and Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)
Subjects: [SDU]Sciences of the Universe [physics], téphrostratigraphie, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Volcanologie, Massif central français, ComputingMilieux_MISCELLANEOUS
Abstract: National audience
Published: 2012

40. Sigmoidal particle density distribution in a subplinian scoria fall deposit

Author: Jean-Luc Le Pennec, Julia Eychenne, Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), and Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS)
Subjects: geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, [SDE.MCG]Environmental Sciences/Global Changes, Mineralogy, 010502 geochemistry & geophysics, Sigmoidal law, 01 natural sciences, Volcano, Geochemistry and Petrology, Gas pycnometer, Pumice, Clastic rock, Componentry proportions, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Sample collection, Scoria, Tephra, Particle density, Density distributions, Geology, 0105 earth and related environmental sciences, Volume-to-mass conversion
Abstract: A general expression to describe particle density distribution in tephra fall deposits is essential to improve fallout tephra mass determination and numerical modelling of tephra dispersion. To obtain particle density distributions in tephra fall deposits, we performed high-resolution componentry and particle density analyses on samples from the 2006 subplinian eruption of Tungurahua volcano in Ecuador. Six componentry classes, including pumice and scoria, have been identified in our sample collection. We determined the class of 300 clasts in each 0.5ϕ fractions from −4.5ϕ to 3.5ϕ and carried out water pycnometry density measurements on selected size fractions. Results indicate that the mean particle density increases with ϕ up to a plateau of ~2.6 g/cm3 for clasts finer than 1.5ϕ. The density of scoria and pumice increases between −3 and 1ϕ, while dense particle density is sub-constant with grainsize. We show that the mean particle density μ of the vesicular fractions is a function of grainsize i (ϕ scale) given by a sigmoidal law: $$ \mu (i)={{{K+\beta }} \left/ {{\left( {1+\alpha {e^{-ri }}} \right)}} \right.} $$ , where K, β, α and r are constants. These sigmoidal distributions can be used to determine accurately the load of each componentry class and should be applicable to many tephra deposits and for modelling purposes.
Published: 2012

41. Petrological analysis of the pre-eruptive magmatic process prior to the 2006 explosive eruptions at Tungurahua volcano (Ecuador)

Author: Pablo Samaniego, Jean-Luc Le Pennec, Silvana Hidalgo, Claude Robin, Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), instituto Geofísico, Escuela Politécnica Nacional (EPN), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), and Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 010504 meteorology & atmospheric sciences, [SDE.MCG]Environmental Sciences/Global Changes, plumbing system, Geochemistry, Pyroclastic rock, system, 010502 geochemistry & geophysics, 01 natural sciences, magma mixing, recharge, Geochemistry and Petrology, Pumice, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, geography, geography.geographical_feature_category, Explosive eruption, Tungurahua, Volcanic rock, Geophysics, Volcano, 13. Climate action, Magma, plumbing, Phenocryst, Ecuador, Scoria, thermobarometry, Geology
Abstract: International audience; Understanding the processes at the origin of explosive events is crucial for volcanic hazard mitigation, especially during long-lasting eruptions at andesitic volcanoes. This work exposes the case of Tungurahua volcano, whose unrest occurred in 1999. Since this date, the eruptive activity was characterized by low-to moderate explosiveness, including phases with stronger canon-like explosions and regional ash fallout. However, in 2006, a sudden increase of the explosiveness led to pyroclastic flow-forming eruptions on July 14th (VEI 2) and August 16–17th (VEI 3). All magmas emitted from 1999 to 2005, as well as the samples from the 2006 eruptions, have homogeneous bulk-rock andesitic compositions (58–59 wt.% SiO2), and contain the same mineral assemblage consisting of pl + cpx + opx + mag ± ol. However, during the August 16–17th event, the erupted tephra comprise two types of magmas: a dominant, brown andesitic scoria; and scarce, light-grey pumice representing a subordinate, silica-rich juvenile component. For the andesitic magma, thermobarometric data point to magmatic temperatures ranging from 950 to 1015 °C and pressures in the range of 200 to 250 MPa, which corresponds to 7.5–9.5 km below the summit. Disequilibrium textures in plagioclase and pyroxene phenocrysts, particularly thin overgrowth rims, indicate the recharge of this magma body by mafic magma. Between 1999 and 2005, repeated injections from depth fed the intermittent eruptive activity observed while silica-rich melts were produced by in-situ crystallization in the peripheral parts of the reservoir. In April 2006, the recharge of a primitive magma produced strong convection and homogenisation in the reservoir, as well as pressure increase and higher magma ascent rate after seven years of only moderately explosive activity. This work emphasizes the importance of petrological studies in constraining the pre-eruptive magmatic conditions and processes, as a tool for understanding the fundamental causes of the changes in the eruptive dynamism, particularly the occurrence of paroxysmal phases in andesitic systems with open-vent behaviour.
Published: 2011

42. Le point sur l'eruption du lac Pavin il y a 7000 ans

Author: Boivin, Pierre, Besson, Jean-Claude, Ferry, P., Gourgaud, A., Miallier, Didier, Thouret, Jean-Claude, Vernet, Gérard, Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Departement des Sciences de la Terre, Ecole Nationale Superieure de Lyon, Laboratoire de Physique Corpusculaire - Clermont-Ferrand (LPC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Géographie Physique et Environnementale (GEOLAB), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Université Clermont Auvergne (UCA)-Institut Sciences de l'Homme et de la Société (IR SHS UNILIM), Université de Limoges (UNILIM)-Université de Limoges (UNILIM)-Centre National de la Recherche Scientifique (CNRS), Institut national de recherches archéologiques préventives (Inrap), Pellet, Jeanine, Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut Sciences de l'Homme et de la Société (IR SHS UNILIM), and Université de Limoges (UNILIM)-Université de Limoges (UNILIM)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA)
Subjects: eruption, [SDE.MCG] Environmental Sciences/Global Changes, lac Pavin, [SDE.MCG]Environmental Sciences/Global Changes, [SDU.STU.VO] Sciences of the Universe [physics]/Earth Sciences/Volcanology, volcan, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology
Published: 2011

43. Three dimensional transport speed of wind-drifted ash plumes using ground-based radar

Author: Donnadieu, Franck, Vallade, Sébastien, Moune, Séverine, Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), and Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS)
Subjects: [SDE.MCG]Environmental Sciences/Global Changes, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, ComputingMilieux_MISCELLANEOUS
Abstract: International audience
Published: 2011

44. Dynamic magma mixing revealed by the 2010 Eyjafjallajökull eruption

Author: Olgeir Sigmarsson, G. Larsen, Séverine Moune, Thor Thordarson, Ármann Höskuldsson, Jakob K. Keiding, Ivan Vlastélic, Ilya N. Bindeman, Jean-Luc Devidal, Rasmus Andreasen, Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institute of Earth Sciences, University of Iceland [Reykjavik], Department of Earth Science and Technology [Imperial College London], Imperial College London, Department of Geological Sciences [Oregon], University of Oregon [Eugene], GeoForschungsZentrum - Helmholtz-Zentrum Potsdam (GFZ), Institute of Earth Sciences [Reykjavik], University of Edinburgh, Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), and Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 010504 meteorology & atmospheric sciences, [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, [SDE.MCG]Environmental Sciences/Global Changes, Geochemistry, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Igneous differentiation, 010502 geochemistry & geophysics, 01 natural sciences, Geology, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract: Injection of basaltic magmas into silicic crustal holding chambers and subsequent mixing of the two components is a process that has been recognised since the late seventies to have resulted in explosive eruptions. Detailed reconstruction and assessment of the mixing process caused by such intrusion is now possible because of the exceptional time-sequence sample suite available from the tephra fallout of the 2010 summit eruption at Eyjafjallajökull volcano in South Iceland. From 14 to 19 April the tephra contains three glass types of basaltic, intermediate, and silicic compositions recording rapid magma mingling without homogenisation, involving evolved FeTi-basalt and dacite with composition identical to that produced by the 1821–1823 AD Eyjafjallajökull summit eruption. The time-dependent change in the magma composition suggests a binary mixing process with changing end-member compositions and proportions, or dynamic magma mixing. Beginning of May, a new injection of deep-derived basalt was recorded by deep seismicity, appearance of magnesium-rich olivine phenocrysts together with high sulphur output and presence of sulphide crystals. Thus the composition of the basaltic injection became more primitive and hotter with time prowoking changes in the silicic mixing end-member from pre-existing melt to the solid carapace of the magma chamber. Decreasing proportions of the mafic end-member with time in the erupted mixed-magma, demonstrate that injections of Mg-rich basalt was the motor of the 2010 Eyjafjallajökull explosive eruption, and that its decreasing inflow terminated the eruption. Significant quantity of silicic magma is thus still present in the interior of the volcano. Our results show that detailed sampling during the entire eruption was essential for deciphering the complex magmatic processes at play, namely the dynamic magma mixing. Finally, the rapid compositional changes in the eruptive products suggest that magma mingling occurs on a timescale of few hours to days whereas the interval between the first detected magma injection and eruption was several months.
Published: 2011

45. Pre-explosive conduit conditions of the 1997 Vulcanian explosions at Soufrière Hills Volcano, Montserrat: II. Overpressure and depth distributions

Author: Laurent Arbaret, Alain Burgisser, Timothy H. Druitt, Thomas Giachetti, Institut des Sciences de la Terre d'Orléans (ISTO), Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS), ANR-05-CATT-0003,EXPLANT,EXPLANT : Explosivité de domes de lave - approche analytique, expérimentale et numérique - application aux volcans Antillais(2005), Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Université de Tours-Centre National de la Recherche Scientifique (CNRS), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement et la société-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Université Jean Monnet [Saint-Étienne] (UJM), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), and Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC)
Subjects: Soufrière Hills Volcano, decompression, Montserrat, 010504 meteorology & atmospheric sciences, Explosive material, [SDE.MCG]Environmental Sciences/Global Changes, engineering.material, 010502 geochemistry & geophysics, 01 natural sciences, conduit modeling, Microlite, Electrical conduit, Geochemistry and Petrology, Transition zone, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Vesicular texture, 0105 earth and related environmental sciences, geography, geography.geographical_feature_category, Overpressure, Geophysics, Volcano, engineering, Layering, Geology, Seismology
Abstract: International audience; A type example of Vulcanian eruptive dynamics is the series of 88 explosions that occurred between August and October 1997 at Soufrière Hills volcano on Montserrat Island. These explosions are interpreted to be caused by the pressurization of a conduit by a shallow highly crystalline and degassed magma plug. We test such an interpretation by combining the pressures and porosities of the pre-explosive magma column proposed by Burgisser et al. (2010, doi:10.1016/j.jvolgeores.2010.04.008) into a physical model that reconstructs a depth-referenced density profile of the column for four mechanisms of pressure buildup. Each mechanism yields a different overpressure profile: 1) gas accumulation, 2) conduit wall elasticity, 3) microlite crystallization, and 4) magma flowage. For the first three mechanisms, the three-part vertical layering of the conduit prior to explosion was spatially distributed as a dense cap atop the conduit with a thickness of a few tens of meters, a transition zone of 400–700 m with heterogeneous vesicularities, and, at greater depth, a more homogeneous, low-porosity zone that brings the total column length to ~ 3.5 km. A shorter column can be obtained with mechanism 4: a dense cap of less than a few meters, a heterogeneous zone of 200–500 m, and a total column length as low as 2.5 km. Inflation/deflation cycles linked to a periodic overpressure source offer a dataset that we use to constrain the four overpressure mechanisms. Magma flowage is sufficient to cause periodic edifice deformation through semi-rigid conduit walls and build overpressures able to trigger explosions. Gas accumulation below a shallow plug is also able to build such overpressures and can occur regardless of magma flowage. The concurrence of these three mechanisms offers the highest likelihood of building overpressures leading to the 1997 explosion series. We also explore the consequences of sudden (eruptive) overpressure release on our magmatic columns to assess the role of syn-explosive vesiculation and pre-fragmentation column expansion. We find that large shallow overpressures and efficient syn-explosive vesiculation cause the most dramatic pre-fragmentation expansion. This leads us to depict two end-member pictures of a Vulcanian explosion. The first case corresponds to the widely accepted view that the downward motion of a fragmentation front controls column evacuation. In the second case, syn-explosive column expansion just after overpressure release brings foamed-up magma up towards an essentially stationary and shallow fragmentation front.
Published: 2011

46. L'usage des trachytes de la Chaîne des Puys dans l'antiquité

Author: Miallier, Didier, Boivin, Pierre, Dousteyssier, Bertrand, Laboratoire de Physique Corpusculaire - Clermont-Ferrand (LPC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre d'Histoire 'Espaces et Cultures' (CHEC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP), Pellet, Jeanine, Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), and Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS)
Subjects: [SDE.MCG] Environmental Sciences/Global Changes, trachyte, [SHS.ARCHEO] Humanities and Social Sciences/Archaeology and Prehistory, [SHS.ARCHEO]Humanities and Social Sciences/Archaeology and Prehistory, [SDE.MCG]Environmental Sciences/Global Changes, [SDU.STU.VO] Sciences of the Universe [physics]/Earth Sciences/Volcanology, volcans, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, kilian, Chaîne des Puys, antiquité
Abstract: Rapport d'opération archéologique Opération de prospection thématique annuelle Opération archéologique n° 6889 Arrêté n° 2011-130; Un relevé 3D LiDAR du centre de la Chaîne des Puys, effectué en mars 2011 (Coordination Centre Régional Auvergnat de l'Information Géographique, CRAIG ; contrôle scientifique P. Labazuy, LMV-OPGC, UBP), a compris spécifiquement la zone du Kilian en haute résolution. Le fichier définitif a été livré au CRAIG au mois d'octobre 2011, suite à quoi il a été possible d'extraire les données intéressant le Kilian. Leur analyse a permis de mettre en évidence la très forte anthropisation du cratère et sa complexité. Elle a, de plus, aidé à la définition des parcours d'investigations géophysiques qui seront effectués en 2012. Une campagne de prospection systématique des dépôts de fouille et dépôts de musées (Musées de la Ville de Clermont, dépôts DRAC, INRAP, Conseil Général du Puy-de-Dôme) a été entreprise afin de repérer tous les trachytes gallo-romains provenant, soit de fouilles et découvertes fortuites anciennes - et conservés dans des collections publiques - soit de fouilles récentes. Plusieurs dizaines d'objets ont ainsi pu être inventoriés. Par suite, des prélèvements systématiques de trachyte ont été effectués, en donnant la priorité à des objets documentés et datables. Des lames minces ont été réalisées et analysées. Les conclusions des analyses confirment que le Kilian a été, de beaucoup, la principale source de trachyte dès la seconde moitié du premier siècle de notre ère, aussi bien dans le secteur du puy de Dôme qu'en Limagne. En outre, de rares éléments témoignent ponctuellement de l'utilisation d'autres trachytes : trachyte du puy de Dôme, du Sarcouy et du Clierzou (ou de l'Aumône). En parallèle, des prélèvements de trachyte sur les sites potentiels d'exploitation (volcans trachytiques), ont été poursuivis de façon à enrichir et affiner notre base de données. Enfin, de nouvelles analyses d'éléments traces non encore pris en compte (séries U et Th) ont montré que ces derniers pouvaient être très discriminants dans la recherche des sources.
Published: 2011

47. Three-dimensional textural analysis of products from the 1997 Vulcanian explosions of Soufrière Hills Volcano, using X-ray computed microtomography

Author: Giachetti, Thomas, Burgisser, Alain, Arbaret, Laurent, Druitt, Timothy H., Kelfoun, Karim, Laboratoire de Géographie Physique et Environnementale (GEOLAB), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Université Clermont Auvergne (UCA)-Institut Sciences de l'Homme et de la Société (IR SHS UNILIM), Université de Limoges (UNILIM)-Université de Limoges (UNILIM)-Centre National de la Recherche Scientifique (CNRS), Institut des Sciences de la Terre d'Orléans (ISTO), Université de Tours-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut Sciences de l'Homme et de la Société (IR SHS UNILIM), Université de Limoges (UNILIM)-Université de Limoges (UNILIM)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA), Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), and POTHIER, Nathalie
Subjects: [SDE.MCG] Environmental Sciences/Global Changes, [SDE.MCG]Environmental Sciences/Global Changes, [SDU.STU.VO] Sciences of the Universe [physics]/Earth Sciences/Volcanology, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology
Abstract: International audience; X-ray computed microtomography is a powerful, non-destructive method for imaging textures and for quantifying vesicle spatial relationships and size distributions. It was applied to one breadcrust bomb and three pumices from the 1997 Vulcanian explosions of the Soufrière Hills Volcano, Montserrat. A detailed 2D textural study of these same samples, including high-resolution vesicle size distributions, has already been carried out. In order to cover the wide range of vesicle and crystal sizes (few µm to a few hundreds of µm), we acquired tomographic images at three magnifications (0.37, 4.0 and 17.4 µm voxel-1) on each sample. Each magnification covers only part of the whole vesicle size range, but with large overlaps. Vesicle walls were reconstructed using ImageJ and 3DMA_Rock softwares, and a Matlab code was written to combine the data from the three stacks and to calculate vesicle size and sphericity distributions for the whole sample. Comparison with the 2D results show only minor differences in the vesicle size distributions. Cumulative vesicle number densities obtained by the two methods are of the same order of magnitude (~1015 m-3 of glass). Three vesicle populations are recognized in the samples, the same three recognized in 2D, although minor shifts in modes are observed. As in 2D, vesicle sphericity decreases with size, vesicle shape being progressively more complicated as the vesicle grows and coalesces with neighbours. Coalescence in all samples appears to occur between neighbouring vesicles of any sizes, but, as intuitively expected, the larger the vesicle, the more connected it is. Our results show that coalescence affected indifferently pre- and syn-eruptive bubbles. This suggests that the syn-eruptive gas was rapidly connected to large-scale pathways through which it could escape. Depending on clast permeability, this mechanism has the potential to double the amount of gas available for propulsion of the Vulcanian jet.
Published: 2010

48. Redox Transfers at Subduction Zones: The Fluid-Melt-Rock Connection

Author: Gaillard, Fabrice, Iacono-Marziano, Giada, Delacourt, Adélie, Laporte, Didier, Institut des Sciences de la Terre d'Orléans (ISTO), Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), POTHIER, Nathalie, Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Université de Tours-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), and Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: [SDE.MCG] Environmental Sciences/Global Changes, [SDE.MCG]Environmental Sciences/Global Changes, [SDU.STU.VO] Sciences of the Universe [physics]/Earth Sciences/Volcanology, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology
Abstract: International audience; Oxygen fugacity (fO2) of mantle rocks and their derived magmas is a measure of their redox state, which influences the compositions of both minerals and fluids, and the fate of redox sensitive elements such as (noble) metals, iron, hydrogen, sulfur, carbon. fO2 is commonly expressed in log-unit relative to that buffered by the quartz-fayalite-magnetite mineral assemblage, FMQ. Many mantle regions have fO2 close to FMQ and produce magmas that are within the same range of fO2. Recent surveys have also concluded that the mantle redox state has been steady since the archean times. The mantle at subduction zones (~10% of global magmatism) is, however, much more oxidized and can display fO2 up to 2 log-units higher than FMQ. Because mantle redox state directly impacts on the one of melts and volcanic gases emitted at surface, how mantle fO2 can vary spatially and through the ages of the Earth is a fundamental issue for our understanding of the exchanges between the innermost and the outermost parts of our planet. Of prime interest is the question of the role of mantle redox state and the one of the derived volcanic gases on the atmospheric oxygen rise at 2.5 Ga. At subduction zones, volatile-rich rocks are entrained with the oceanic lithosphere into the mantle where melting occurs. Water is the major volatile involved in the dynamic of subduction zones. The oxidized nature of subduction- or Arc-magmas might be related to their water-rich nature but this link remains unclear, as illustrated by the identification of hydrous magmas that can be strongly reduced in other geodynamic settings. From a thermodynamic point of view, water-rich fluids might be oxidizing if their equilibrium hydrogen fugacity is low (molar abundance much less than 1%). Water in subduction-magma mainly derives from serpentinite dehydration within the plunging lithosphere at depth. This dehydration takes place within rocks that have been oxidized by sea floor alteration prior to subduction. We show that serpentinite dehydration produces an extremely oxidized water fluid, with hydrogen content of the order of 0.001 %. Based on experimental petrology and thermodynamic calculations, we estimate the fO2 of this water fluid at FMQ+4.5, mostly buffered by the magnetite-hematite redox buffer. Subsequently, the fluid migrates upward triggering a hyper-oxidative metasomatism of the mantle wedge (affecting sulfur and U/Th ratios), the production of arc-basalts and emission of oxidized volcanic gases into atmosphere. Upon percolation through the mantle wedge this fluid looses its hyper oxidant nature and reaches FMQ+2 when in the form of arc-basalts. The dehydrated oxidized subducted rocks, which displays ferric to total iron around 60%, are entrained deeper in the mantle. Overall, subduction triggers an oxygen transfer from the surface to the interior of our planet and, therefore, could not have facilitated the oxidation of the atmosphere.
Published: 2010

49. Rapport de sondages et d'analyses, Le Kilian et les carrières anciennes de trachyte dans la Chaîne des Puys (Puy-de-Dôme)

Author: Miallier, Didier, Boivin, Pierre, Cluzel, N., Auzanneau, E., Besson, Jean-Claude, Besson, J., Chabert, S., Couturié, J.‑p., Dando, M., Devidal, J.‑l., Devouard, Bertrand, Donnadieu, F., Dupoux, A., Pointud, F., Farrié, B., Fruquière, J.‑l., Héritier, V., Labazuy, Philippe, Merle, Antoine, Meunier, G., Parent, D., Petit, S., Pruneyrolles, L., Verdier, P., Dousteyssier, Bertrand, Laboratoire de Physique Corpusculaire - Clermont-Ferrand (LPC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Magmas et Volcans (LMV), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Centre d'Histoire 'Espaces et Cultures' (CHEC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP), Maison des Sciences de l'Homme de Clermont-Ferrand (MSH Clermont), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS), Institut national de recherches archéologiques préventives (Inrap), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), and Pellet, Jeanine
Subjects: [SDE.MCG] Environmental Sciences/Global Changes, sondage, [SHS.ARCHEO] Humanities and Social Sciences/Archaeology and Prehistory, [SHS.ARCHEO]Humanities and Social Sciences/Archaeology and Prehistory, [SDE.MCG]Environmental Sciences/Global Changes, [SDU.STU.VO] Sciences of the Universe [physics]/Earth Sciences/Volcanology, volcans, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology
Abstract: En 2008, l'existence de carrières souterraines médiévales avait été mise en évidence dans la pente ouest du Bois de Manson qui domine la dépression du Cratère Kilian, au pied sud du puy de Dôme. En 2009-2010, des sondages et prospections ont été étendus à tout l'ensemble du Kilian de façon à préciser l'étendue et, si possible, la chronologie de son exploitation dans le passé. Ces travaux ont permis d'observer, dans le fond du cratère et sur son flanc interne ouest, des amoncellements de déblais d'un volume considérable, témoignant d'une extraction de roche à grande échelle durant le haut Moyen Âge et très probablement aussi à l'époque gallo-romaine. Une nouvelle carrière souterraine a été découverte dans la pente interne ouest du cratère. La base du remplissage de cette carrière a livré des charbons datés entre la fin du IV e siècle et le début du VI e siècle par le radiocarbone, tandis que le sommet du remplissage contenait des tessons de céramique datables, par leur typologie, de la fin du V e siècle au début du VIII e siècle. L'état actuel des investigations conduit à faire l'hypothèse que les gallo-romains ont exploité, au fond du cratère, un trachyte compact dont on ne trouve aujourd'hui que les déchets de taille, et dont les affleurements sont masqués par les déblais, tandis que les artisans du Moyen Âge ont recherché un trachyte plus tendre dans les pentes hautes du cratère. Le Kilian doit donc s'ajouter aux trois sources actuellement connues de trachyte d'oeuvre dans le passé, à savoir les volcans Sarcoui, Aumône (ou petit Suchet) et Cliersou. Dès cette découverte, en 2008, s'est posée la question de savoir quelle part éventuelle le trachyte du Kilian avait pu prendre dans la construction du temple de Mercure au sommet du puy de Dôme et dans l'agglomération gallo-romaine située au col de Ceyssat. Pour y répondre, une campagne d'analyses géochimiques et pétrographiques été engagée pour caractériser, aux fins de comparaison, non seulement les trachytes du Kilian et ceux des ruines gallo-romaines, mais, de plus, les trachytes du Cliersou, de l'Aumône et du Sarcoui. Ces analyses ont finalement montré qu'il est possible de faire une discrimination statistiquement significative entre les différents trachytes étudiés, à l'exception de ceux du couple Cliersou-Aumône dont les laves sont très peu différentes les unes des autres. Le résultat le plus remarquable est que tous les trachytes gallo-romains échantillonnés (dont 10 échantillons distincts au temple de Mercure et 10 au col de Ceyssat) se rattachent sans ambiguïté au Kilian. En toute rigueur, ces nouvelles données ne permettent pas d'exclure sans appel la possibilité d'utilisation à l'époque gallo-romaine, au temple de Mercure et au col de Ceyssat, de trachytes provenant d'autres sources que le Kilian (cas des chaperons de mur du col de Ceyssat, provenant du puy de Dôme). Cependant, il faut ajouter qu'un examen visuel des trachytes d'oeuvre dans ces deux sites, portant sur un nombre de moellons et d'éléments architecturaux bien supérieur au nombre de ceux qui ont été analysés, conduit à conclure que leur source est probablement commune. Cette conclusion est basée sur un faciès minéralogique particulier, observable à l'oeil nu ou à la loupe.
Published: 2010

50. Evolving metasomatic agent in the Northern Andean subduction zone, deduced from magma composition of the long-lived Pichincha volcanic complex (Ecuador)

Author: Joseph Cotten, Gilles Chazot, Erwan Bourdon, Pablo Samaniego, Claude Robin, Laboratoire Magmas et Volcans (LMV), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Domaines Océaniques (LDO), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Observatoire des Sciences de l'Univers-Institut d'écologie et environnement-Centre National de la Recherche Scientifique (CNRS), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), and Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 010504 meteorology & atmospheric sciences, Mantle wedge, [SDE.MCG]Environmental Sciences/Global Changes, Geochemistry, 010502 geochemistry & geophysics, 01 natural sciences, Mantle (geology), Adakite, Isotopes, Geochemistry and Petrology, [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Pichincha, 0105 earth and related environmental sciences, Trace elements, Fractional crystallization (geology), biology, Subduction, Andesites, Partial melting, biology.organism_classification, Geophysics, 13. Climate action, Igneous differentiation, Ecuador, Arc magmatism, Geology, Northern Andean Volcanic Zone
Abstract: International audience; Geochemical studies of long-lived volcanic complexes are crucial for the understanding of the nature and composition of the subduction component of arc magmatism. The Pichincha Volcanic Complex (Northern Andean Volcanic Zone) consists of: (1) an old, highly eroded edifice, the Rucu Pichincha, whose lavas are mostly andesites, erupted from 1,100 to 150 ka; and (2) a younger, essentially dacitic, Guagua Pichincha composite edifice, with three main construction phases (Basal Guagua Pichincha, Toaza, and Cristal) which developed over the last 60 ka. This structural evolution was accompanied by a progressive increase of most incompatible trace element abundances and ratios, as well as by a sharp decrease of fluid-mobile to fluid-immobile element ratios. Geochemical data indicate that fractional crystallization of an amphibole-rich cumulate may account for the evolution from the Guagua Pichincha andesites to dacites. However, in order to explain the transition between the Rucu Pichincha andesites and Guagua Pichincha dacites, the mineralogical and geochemical data indicate the predominance of magma mixing processes between a mafic, trace-element depleted, mantle-derived end-member, and a siliceous, trace-element enriched, adakitic end-member. The systematic variation of trace element abundances and ratios in primitive samples leads us to propose that the Rucu Pichincha magmas came from a hydrous-fluid metasomatized mantle wedge, whereas Guagua Pichincha magmas are related to partial melting of a siliceous-melt metasomatized mantle. This temporal evolution implies a change from dehydration to partial melting of the slab, which may be associated with an increase in the geothermal gradient along the slab due to the presence of the subducted Carnegie Ridge at the subduction system. This work emphasizes the importance of studying arc-magma systems over long periods of time (of at least 1 million of years), in order to evaluate the potential variations of the slab contribution into the mantle source of the arc magmatism.
Published: 2010

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