Littérature scientifique sur le sujet « Experimental volcanology »
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Articles de revues sur le sujet "Experimental volcanology"
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Rose, William I., et John Stix. « Experimental Multi-University Graduate Class in Volcanology ». Eos, Transactions American Geophysical Union 87, no 20 (2006) : 198. http://dx.doi.org/10.1029/2006eo200004.
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Scheu, Bettina, Ulrich Kueppers, Sebastian Mueller, Oliver Spieler et Donald B. Dingwell. « Experimental volcanology on eruptive products of Unzen volcano ». Journal of Volcanology and Geothermal Research 175, no 1-2 (juillet 2008) : 110–19. http://dx.doi.org/10.1016/j.jvolgeores.2008.03.023.
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Grunder, Anita, et J. K. Russell. « Welding processes in volcanology : insights from field, experimental, and modeling studies ». Journal of Volcanology and Geothermal Research 142, no 1-2 (avril 2005) : 1–9. http://dx.doi.org/10.1016/j.jvolgeores.2004.10.010.
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Eichheimer, Philipp, Marcel Thielmann, Wakana Fujita, Gregor J. Golabek, Michihiko Nakamura, Satoshi Okumura, Takayuki Nakatani et Maximilian O. Kottwitz. « Combined numerical and experimental study of microstructure and permeability in porous granular media ». Solid Earth 11, no 3 (25 juin 2020) : 1079–95. http://dx.doi.org/10.5194/se-11-1079-2020.
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Abstract. Fluid flow on different scales is of interest for several Earth science disciplines like petrophysics, hydrogeology and volcanology. To parameterize fluid flow in large-scale numerical simulations (e.g. groundwater and volcanic systems), flow properties on the microscale need to be considered. For this purpose experimental and numerical investigations of flow through porous media over a wide range of porosities are necessary. In the present study we sinter glass bead media with various porosities and measure the permeability experimentally. The microstructure, namely effective porosity and effective specific surface, is investigated using image processing. We determine flow properties like tortuosity and permeability using numerical simulations. We test different parameterizations for isotropic low-porosity media on their potential to predict permeability by comparing their estimations to computed and experimentally measured values.
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ZANON, VITTORIO. « Geology and volcanology of San Venanzo volcanic field (Umbria, Central Italy) ». Geological Magazine 142, no 6 (novembre 2005) : 683–98. http://dx.doi.org/10.1017/s0016756805001470.
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The purpose of this paper is to integrate, or even modify where necessary, the geo-volcanological setting outlined by other authors on the history of the small volcanic field of San Venanzo (Umbria, Central Italy). To attain this goal, new accurate field investigations were carried out in that area, coupled with detailed stratigraphic studies and laboratory analyses, to support field evidence with experimental results. The first objective was to stress the importance of a groundwater reservoir whose interaction with magma at various degrees was responsible not only for the explosive character of volcanism in that area, but also for the complex morphology of the volcanic deposits that are widely scattered on the underlying sedimentary basement. Another objective was to clarify the role played by tectonic activity in enhancing the fast and discontinuous ascent of batches of magma from the mantle to the surface, through two different sets of faults, opened by tectonic unrest into the crust, that were also responsible for the morphology and spatial distribution of volcanic centres. This was considered to be very important in consideration of the still-active stress field of the region. Finally, special attention was focused on the presence of a palaeosol between two eruptive sequences, as it most likely denoted a split in the volcanic activity of this site into two separate phases. This observation leads to the conclusion that, in spite of its eruptive characteristics, the small volcano of San Venanzo is not monogenic. For all of these topics, a number of conclusions have been drawn and they are reported with more data in the following sections of this paper.
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Jollands, Michael C., Ralf Dohmen et José Alberto Padrón-Navarta. « Hide and Seek—Trace Element Incorporation and Diffusion in Olivine ». Elements 19, no 3 (1 juin 2023) : 144–50. http://dx.doi.org/10.2138/gselements.19.3.144.
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Olivine, once overlooked as a host of trace elements, is becoming increasingly important for our understanding of the kinetic and equilibrium behaviour of these elements. Much of our understanding of trace element substitution and diffusion in geological materials comes as a result of experimental and petrological studies of olivine. Here, we consider trace element concentrations and incorporation mechanisms, and how these relate to diffusive behaviour. If we understand trace element behaviour in olivine, we have a powerful tool kit that can be directly applied to address many problems in petrology and volcanology. Perhaps more importantly, what we have learned from olivine can be applied to other minerals and aid us in addressing other far-reaching questions from across the Earth sciences.
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Roche, Olivier, et Guillaume Carazzo. « The contribution of experimental volcanology to the study of the physics of eruptive processes, and related scaling issues : A review ». Journal of Volcanology and Geothermal Research 384 (octobre 2019) : 103–50. http://dx.doi.org/10.1016/j.jvolgeores.2019.07.011.
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WITHAM, FRED, et JEREMY C. PHILLIPS. « The dynamics and mixing of turbulent plumes in a turbulently convecting environment ». Journal of Fluid Mechanics 602 (25 avril 2008) : 39–61. http://dx.doi.org/10.1017/s0022112008000682.
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The turbulent motion of buoyant plumes released into turbulently convecting environments is studied. By assuming that the turbulent environment removes fluid from the plume at a rate proportional to a characteristic environmental velocity scale, we derive a model describing the fluid behaviour. For the example of pure buoyancy plumes, entrainment dominates near the source and the plume radius increases with distance, while further from the source removal, or extrainment, of plume material dominates, and the plume radius decreases to zero. Theoretical predictions are consistent with laboratory experiments, a major feature of which is the natural variability of the convection. We extend the study to include the evolution of a finite confined environment, the end-member regimes of which are a well-mixed environment at all times (high convective velocities), and a ‘filling-box’ model similar to that of Baines & Turner (1969) (low convective velocities). These regimes, and the motion of the interface in a ‘filling-box’ experiment, match experimental observations. We find that the convecting filling box is not stable indefinitely, but that the density stratification will eventually be overcome by thermal convection. The model presented here has important applications in volcanology, ventilation studies and environmental science.
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Bulaong, Dessa, Andreus Rodge Cordova, Alvin S. Eusebio, Princess Elise Fernando, Thimothy James Marquez, Clark Kent Santiago, Asly Danaya Santos, Maria Isabelle Santos et Mary Grace Delos Santos. « Tensegriture : Integrating Tensile Integrity into Furniture to Reduce Earthquake Damage ». American Journal of Innovation in Science and Engineering 2, no 3 (6 septembre 2023) : 15–25. http://dx.doi.org/10.54536/ajise.v2i3.1921.
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Few furniture designs are built around the concept of withstanding earthquakes. This capstone project aims to integrate tensegrity into furniture to replicate the earthquake safety measures used on larger scales with seismic isolation and withstand earthquakes better than traditional furniture. The researchers tested the product at the Philippine Institute of Volcanology and Seismology (PHIVOLCS), located at Diliman, Quezon City. The researchers made use of the institute’s earthquake simulator to have the earthquake intensities scaled accurately. They made use of true experimental research design, which gave them access to the scientific method in making the designs for the furniture. The researchers conducted the experiment in four phases, denoted as the research phase, the design phase, the experiment phase, and the evaluation phase. The results showed that the calculated t-value of 35.317 is greater than the critical t-value of 2.56. This meant that tensegrity-integrated furniture is significantly more earthquake-resistant than traditional household furniture. Measures such as adding weights to the structure’s base increase further increase its stability. Tensile integrity integrated into furniture is a modern take on earthquake safety measures, similar to existing ones like seismic isolation. And with the proper setup and more improvements, its earthquake resistance factor can save lives.
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Rasdini, IGA Ari, Ni Made Wedri, VM Endang SP Rahayu et Amelia Putri. « Penggunaan Media Komik Efektif Terhadap Kesiapsiagaan Siswa Dalam Menghadapi Bencana Tanah Longsor ». Jurnal Smart Keperawatan 8, no 2 (21 décembre 2021) : 70. http://dx.doi.org/10.34310/jskp.v8i2.465.
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Tanah longsor merupakan bencana tahunan yang senantiasa melanda disebagian wilayah Indonesia. Terjadinya bencana tanah longsor dapat menimbulkan dampak yang sangat besar baik terhadap kehidupan maupun lingkungan. Berdasarkan data Pusat Vulkanologi dan Mitigasi Bencana Geologi terdapat 918 lokasi rawan tanah longsor yang tersebar diberbagai wilayah di Indonesia. Provinsi Bali merupakan salah satu wilayah yang rawan terhadap tanah longsor. Peningkatkan kesiapsiagaan terhadap bahaya tanah longsor, dapat mengurangi dampak yang ditimbulkan dari bencana tersebut. Penelitian ini bertujuan mengetahui pengaruh penggunaan media komik terhadap kesiapsiagaan siswa dalam menghadapi bencana tanah longsor. Jenis penelitian adalah pre-experimental design dengan rancangan one-roup pretest-posttest menggunakan teknik total sampling dengan jumlah sampel sebanyak 57 orang. Pengumpulan data dilakukan dengan menggunakan kuisioner kesiapsiagaan bencana tanah longsor dan dianalisa dengan uji paired t-test. Hasil penelitian menunjukkan bahwa skor rata-rata kesiapsiagaan siswa sebelum perlakuan 69,68 dan setelah perlakuan sebesar 76,63 dengan selisih rata-rata sebelum dan sesudah perlakuan sebesar 6,94 dengan p value 0,001 sehingga disimpulkan ada pengaruh penggunaan media komik terhadap kesiapsiagaan siswa dalam menghadapi bencana tanah longsor di SDN 1 Sukawana.Kata kunci: bencana tanah longsor; kesiapsiagaan; media komik The Use Of Comics On Student Preparedness In Facing Landslide DisasterABSTRACT Landslides are an annual disaster that always hits parts of Indonesia. The occurrence of landslides can have a huge impact on both life and the environment. Based on data from the Center for Volcanology and Geological Hazard Mitigation, there were 918 landslide-prone locations spread across various regions in Indonesia. Bali Province is one of the areas prone to landslides. Increasing preparedness against landslides can reduce the impact of the disaster. This study was aimed to determine the effect of using comic’s media on student preparedness in dealing with landslides. This type of research was a pre-experimental design with a one-group pretest-posttest design using a total sampling technique with a total sample of 57 people. Data was collected using a landslide disaster preparedness questionnaire, and it was tested by using a paired t-test. The results show the average score of students' preparedness before treatment is 69.68 and after treatment is 76.63 with an average difference before and after treatment of 6.94 with p-value = 0.001. It was concluded that there was an effect of using comic’s media on students' preparedness in dealing with landslides at SDN 1 Sukawana. Keywords: landslide disaster; preparedness; comics’ media
Thèses sur le sujet "Experimental volcanology"
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Kremers, Simon. « Combining experimental volcanology, petrology and geophysical monitoring techniques ». Diss., lmu, 2012. http://nbn-resolving.de/urn:nbn:de:bvb:19-146595.
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Kremers, Simon [Verfasser], et Heiner [Akademischer Betreuer] Igel. « Combining experimental volcanology, petrology and geophysical monitoring techniques : a case study on Mt. Yasur / Simon Kremers. Betreuer : Heiner Igel ». München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2012. http://d-nb.info/1025047176/34.
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Telling, Jennifer Whitney. « An experimental evaluation of the role of water vapor and collisional energy on ash aggregation in explosive volcanic eruptions ». Thesis, Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/43674.
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Eruption dynamics are sensitive to ash aggregation, and ash aggregates (e.g. accretionary lapilli) are commonly found in eruptive deposits, yet few experiments have been conducted on aggregation phenomena using natural materials. Experiments were developed to produce a probabilistic relationship for the efficiency of ash aggregation with respect to particle size, collision kinetic energy and atmospheric water vapor. The laboratory experiments were carried out in an enclosed tank designed to allow for the control of atmospheric water vapor. A synthetic ash proxy, ballotini, and ash from the 2006 eruption of Tungurahua, in Ecuador, were examined for their aggregation potential. Image data was recorded with a high speed camera and post-processed to determine the number of collisions, energy of collisions and probability of aggregation. Aggregation efficiency was dominantly controlled by collision kinetic energy and little to no dependence on atmospheric water vapor was seen in the range of relative humidity conditions tested, 20 to 80%. Equations governing the relationships between aggregation efficiency and collision kinetic energy and the related particle Stokes number, respectively, were determined for implementation into large scale numerical volcanic models.
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Brugier, Yann-Aurélien. « Magmatologie du Piton de la Fournaise (Ile de la Réunion) : approche volcanologique, pétrologique et expérimentale ». Thesis, Orléans, 2016. http://www.theses.fr/2016ORLE2007/document.
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Afin de parvenir à une meilleure compréhension des processus d’évolution des magmas réunionnais, nous avons réalisé une étude ayant pour objectifs principaux : (1) la simulation expérimentale du système d’alimentation du Piton de la Fournaise, à partir d’un matériel de départ de composition typique de Steady State Basalt et dans des conditions de pression, température, fO2 et de teneurs en volatils (H2O, CO2) réalistes ; (2) la détermination de la séquence de cristallisation d’échantillons représentatifs des roches plutoniques réunionnaises de façon à les comparer avec les résultats expérimentaux et (3) l’obtention d’une base de données volcanologiques, pétrologiques et géochimiques significative sur le groupe de laves anormales (« Abnormal Group ») permettant de confirmer son existence dans le système d’alimentation du Piton de la Fournaise. La découverte de verres silicatés ayant des compositions caractéristiques de l’Abnormal Group confirme l’implication de ces magmas dans l’activité éruptive. Toutefois, les roches plutoniques n’enregistrent pour la plupart que des séquences de cristallisation témoignant d’une évolution superficielle des magmas. Cette dernière est simulée de façon satisfaisante par les expérimentations réalisées dans la gamme 0.1 à 50 MPa qui conduisent à des modèles pétrologiques et des pressions de stockage en accord avec les données géophysiques. Les expérimentations à plus forte pression démontrent l’existence de paliers au sein du système d’alimentation qui peuvent en grande partie expliquer les diverses compositions réunionnaises, mais posent la question de la composition des magmas parentauxTo better understand magmatic processes associated with the evolution of La Réunion magmas, we have carried out a multi-approach study aimed at (1) simulating experimentally the feeding system of the Piton de la Fournaise volcano, using a Steady State Basalt starting material and P-T-fO2-Volatiles (H2O, CO2) conditions compatible with the natural system; (2) determining crystallization sequences representative of La Réunion plutonic rocks for comparison with the experimental results and (3) constructing a volcanological, petrological and geochemical database for lavas of the Abnormal Group, to confirm the existence of Abnormal melts in the feeding system of the volcano. The discovery of glasses having chemical characteristics similar to the Abnormal Group establishes the implication of Abnormal melts in eruptive processes. However, plutonic rocks record crystallization sequences that for the most part indicate a low pressure magmatic evolution. Experiments in the pressure range 0.1 to 50 MPa satisfactorily reproduce conditions in the shallow magmatic systems and lead to petrological models and magma storage depths in agreement with geophysical data. Experiments at higher pressures demonstrate transitions in magma fractionation mechanisms in the feeding system that can explain the range of erupted compositions, but call into question the compositions of parental magmas
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Penlou, Baptiste. « Étude expérimentale des écoulements gaz-particules en contexte de fontaine pyroclastique ». Electronic Thesis or Diss., Université Clermont Auvergne (2021-...), 2023. http://www.theses.fr/2023UCFA0159.
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Les colonnes pyroclastiques se forment lors d'éruptions volcaniques explosives au cours desquelles un mélange de gaz et de particules est éjecté à grande vitesse depuis un évent et peut conduire à la formation de panaches convectifs. La stabilité de ces colonnes dépend de divers paramètres qui peuvent varier au cours du temps et causer l'effondrement partiel ou total du mélange pyroclastique. Ces effondrements donnent naissance à des fontaines éruptives à l'origine de courants de densité pyroclastiques (CDPs). L'objectif de cette thèse est double : étudier (1) les mécanismes de sédimentation des particules dans le panache et la partie diluée des CDPs et (2) les mécanismes d'émergence des CDPs dans les zones d'impacts des fontaines. La méthode choisie est l'approche expérimentale.Une première série d'expériences consiste à mettre en suspension des particules de taille variant de 49 à 467,5 µm dans un dispositif cylindrique et à mesurer la concentration locale de particules de chaque mélange. Pour cela, deux approches indépendantes ont été utilisées et ont donné des résultats similaires : une méthode acoustique et l'utilisation des capteurs de pression. Ces expériences mettent en lumière deux mécanismes de sédimentation des particules : la sédimentation améliorée et la sédimentation retardée. Dans les suspensions de petites particules (78 µm), la vitesse de sédimentation augmente avec la concentration locale de particules en raison de la formation de « clusters » qui chutent à une vitesse quatre fois supérieure à la vitesse terminale de sédimentation des particules individuelles (sédimentation améliorée). En revanche, dans les suspensions de plus grandes particules (467,5 µm), la vitesse de sédimentation diminue avec l'augmentation de la concentration de particules malgré la présence de « clusters » et elle est 30 % inférieure à la vitesse de chutes des particules individuelles (sédimentation retardée). Ces résultats suggèrent que les mécanismes de sédimentation en présence de « clusters » et se produisant dans les panaches où la partie diluée des courants de densité pyroclastiques devraient être pris en compte dans les modèles utilisés pour simuler ces phénomènes volcaniques afin de mieux prédire les caractéristiques des dépôts.Une seconde série d'expériences consiste à simuler une fontaine pyroclastique en relâchant dans un chenal des particules de tailles comprises entre 29 et 269 µm et à une hauteur de 3,27 m. Les résultats montrent que les mélanges dilués (1,6 - 4,4 vol.%) en chute libre s'accumulent dans la zone d'impact pour former des écoulements granulaires concentrés (~ 45 - 48 vol.%) dont la pression de fluide interstitiel compense presque totalement le poids des particules pour des tailles < 76 µm. De plus, la pression de fluide maximale mesurée à l'impact, la distance de parcours des écoulements et l'étirement horizontal des dépôts augmentent avec la diminution de taille des particules. En considérant le dimensionnement des expériences, ces résultats indiquent qu'une pression de fluide interstitielle élevée dans les courants de densité pyroclastiques concentrés peut être générée dans la zone d'impact des fontaines pyroclastiques en effondrement. La petite taille des particules, qui cause une faible perméabilité et un long temps de diffusion de la pression de pore, peut être l'un des facteurs principaux qui causent les longues distances parcourues par les écoulementsPyroclastic columns form during explosive volcanic eruptions in which a mixture of gases and particles is ejected at high speed from a vent and can lead to the formation of convective plumes. The stability of these columns depends on various parameters that can vary over time and cause partial or total collapse of the pyroclastic mixture. These collapses give rise to eruptive fountains, forming density currents called pyroclastic density currents (PDCs). The objective of this thesis is twofold: to study (1) the mechanisms of particle sedimentation in the plume and the dilute part of PDCs, and (2) the mechanisms of PDC emergence in the impact zones of the fountains. The chosen method is the experimental approach.A first series of experiments involves suspending particles ranging in size from 49 to 467.5 µm in a cylindrical device and measuring the local particle concentration for each mixture. For this purpose, two independent approaches were used and provided similar results: an acoustic method and the use of pressure sensors. These experiments highlight two mechanisms of particle sedimentation: enhanced sedimentation and delayed sedimentation. In suspensions of small particles (78 µm), the sedimentation rate increases with the local particle concentration due to the formation of « clusters » that fall at a speed four times higher than the terminal settling velocity of individual particles (enhanced sedimentation). However, in suspensions of larger particles (467.5 µm), the sedimentation rate decreases with increasing particle concentration, despite the presence of « clusters » and it is 30 % lower than the settling speed of individual particles (delayed sedimentation). These results suggest that the sedimentation mechanisms in the presence of « clusters » occurring in plumes or the dilute part of PDC should be considered in models used to simulate these volcanic phenomena to better predict deposit characteristics.A second series of experiments simulates a pyroclastic fountain by releasing particles of sizes ranging from 29 and 269 µm into a channel at a height of 3.27 meters. The results show that dilute mixtures (1.6 - 4.4 vol.%) in free fall accumulate in the impact zone to form concentrated granular flows (~ 45 - 48 vol.%) whose interstitial fluid pressure nearly compensates for the weight of particles for sizes < 76 µm. Furthermore, the maximum fluid pressure measured at the impact, the flow travel distance, and the horizontal stretching of deposits increase with decreasing particle size. Considering the experiment dimensions, these results indicate that a high interstitial fluid pressure can be generated in the impact zone of collapsing pyroclastic fountains. The small particle size, causing low permeability and a long pressure diffusion time, may be one of the main factors leading to the long runout distances covered by the flows
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Chédeville-Monzo, Corentin. « Mécanismes d'auto-fluidisation des écoulements pyroclastiques : approche expérimentale ». Thesis, Clermont-Ferrand 2, 2016. http://www.theses.fr/2016CLF22684/document.
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Les écoulements pyroclastiques sont des mélanges à haute température de gaz et de particules volcaniques qui peuvent se propager sur de très grandes distances. Cette forte « mobilité » est souvent attribuée à leur capacité à se fluidiser, c’est-à-dire à générer et conserver une forte pression interstitielle de gaz qui réduit les forces de friction interne. L’objectif principal de cette thèse est de comprendre comment les irrégularités des terrains sur lesquelles se propagent les écoulements pyroclastiques peuvent favoriser leur fluidisation. Une première série d’expériences de laboratoire a consisté à générer des écoulements de particules fines (diamètre de 45-90 μm) sur des substrats de différentes rugosités. Les résultats montrent que la distance de parcours des écoulements augmente avec la rugosité, allant jusqu’à doubler par rapport à la distance de parcours sur fond lisse. Des analyses de vidéos haute vitesse et des mesures de pression interstitielle d’air à la base des écoulements montrent que la tête (partie antérieure) des écoulements qui se propagent sur un substrat rugueux s’auto-fluidisent en conséquence de la sédimentation des particules dans les interstices du substrat, chassant l’air qui remonte et percole dans l’écoulement. Ce mécanisme d’auto-fluidisation est efficace pour toutes les inclinaisons étudiées (0-30°), suggérant qu’il est susceptible de se produire tout au long de la mise en place d’un écoulement pyroclastique. Une seconde étude a consisté à faire chuter des lits de particules dans une colonne statique. Les résultats montrent que même pour une hauteur de relâchement relativement faible (20 cm), le mélange peut entièrement s’auto-fluidiser durant sa chute. Quand les particules sont suffisamment fines (<100 μm) la pression interstitielle dans le dépôt diffuse pendant plusieurs secondes, la durée de cette diffusion augmentant avec l’augmentation de l’épaisseur du lit et la diminution de taille des particules. Les temps de diffusions les plus longs sont observés avec un matériau provenant d’un dépôt d’écoulement pyroclastique (~30 s pour des lits de 28.5 cm d’épaisseur). Ces résultats suggèrent que les écoulements pyroclastiques qui se propagent sur des terrains accidentés peuvent s’auto-fluidiser et conserver une faible friction au cours de leur mise en placePyroclastic flows are hot mixtures of gas and particles that can propagate over large distances. This high “mobility” is often attributed to their ability to be fluidized, that is, to generate and retain high gas pore pressure that reduces internal friction forces. The main objective of this thesis is to understand how irregularities of substrates on which pyroclastic flows propagate can enhance their fluidization. A first set of laboratory experiments consisted of the generation of fine-grained flows (diameter of 45-90 μm) on substrate of various roughness. Results show that the flow runout distance increases with the substrate roughness, and is up to twice the runout on a smooth substrate. High speed video analyses and air pore pressure measurements at the flow base show that the flow head propagating over a rough substrate can auto-fluidize because of particles sedimentation into the substrate interstices, which forces the air to escape upward and percolate through the flow. This auto-fluidization mechanism is efficient at all inclinations investigated (0-30°), suggesting that it could occur during the whole emplacement of a pyroclastic flow. A second study consisted of the vertical release of beds of particles in a static column. Results show that the granular mixture can be fully fluidized, even when collapsing from a relatively low height (20 cm). When particles are fine enough (<100 μm), pore pressure in the deposit diffuses for several seconds, the diffusion duration increasing with increasing bed thickness and decreasing particle size. The longest diffusion durations are observed for pyroclastic flow deposit materials (~30 s for 28.5 cm thick beds). These results suggest that pyroclastic flows propagating on irregular terrains can auto-fluidize and preserve low internal friction during their emplacement
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Telling, Jennifer Whitney. « Microphysical processes of volcanic ash aggregation and their implications for volcanic eruption dynamics ». Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/52925.
Texte intégralRésumé :
Although numerous hazard models exist to assess possible ash fallout from explosive volcanic eruptions around the world, these models frequently neglect to consider ash aggregation or use a simple percent proxy to represent aggregation, without considering the varying processes at work throughout the volcanic flow. Eruption dynamics are sensitive to ash aggregation, and ash aggregates are commonly found in eruptive deposits, yet few experiments have been conducted on aggregation phenomena using natural materials. In this work, experiments were developed to produce both probabilistic and process-based relationships for the efficiency of ash aggregation with respect particle size, collision kinetic energy, atmospheric water vapor and residence time. A synthetic ash proxy, ballotini, and ash from the 2006 eruption of Tungurahua, Ecuador, and the 1980 eruption of Mount St. Helens, WA, were examined for their aggregation potential.
Two aggregation regimes, wet and dry, were identified based on their potential for aggregation. The wet flow regime occurs when particles are circulated in high relative humidity environments long enough to develop a water layer with a thickness that exceeds the particle roughness scale. Hydrodynamic forces control aggregation in the wet flow regime. The dry flow regime includes particles in low relative humidity environments as well as those that circulate too briefly in high humidity environments to fully develop a water layer. Electrostatic forces control aggregation in the dry flow regime. Aggregation efficiency in both regimes was dominantly controlled by collision kinetic energy; however, this effect is significantly dampened in the wet flow regime. Equations governing the relationships between aggregation efficiency, collision kinetic energy and the related forcings in the wet or dry flow regimes have been developed for implementation into large-scale numerical volcanic models.
The results of this experimental work have been developed into a probability distribution that has been integrated and incorporated into a multifluid numerical model. The numerical simulation was tested on a range of explosive depths and overpressure estimates from the 1790 eruption of Kilauea volcano, HI. The model output was compared to field data collected on the deposit thickness moving away from the source and the distribution, including both size and density, of aggregates. The mass fraction of ash removed from the eruption column in the form of aggregates was also calculated to examine how efficiently aggregation processes remove ash throughout the eruption. Cumulatively, the work presented here furthers our understanding of aggregation processes and the role they play in volcanic eruptions.
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Dietterich, Hannah. « Remote Sensing, Morphologic Analysis, and Analogue Modeling of Lava Channel Networks in Hawai`i ». Thesis, University of Oregon, 2014. http://hdl.handle.net/1794/18335.
Texte intégralRésumé :
Lava flows are common at volcanoes around the world and on other terrestrial planets, but their behavior is not fully understood. In Hawai`i, advances in remote sensing are offering new insights into lava flow emplacement. In this dissertation, I develop new techniques using satellite-based synthetic aperature radar, aerial photographs, and airborne lidar to produce three-dimensional high-resolution maps of lava flows from data collected before, during, and after emplacement. These new datasets highlight complex lava channel networks within these flows, which are not incorporated into current predictive or probabilistic lava flow models yet may affect flow behavior. I investigate the origin and influence of these channel networks through morphologic analysis of underlying topography, network topology, and flow morphology and volume. Channel network geometries range from distributary systems dominated by flow branching around local obstacles to tributary systems constricted by topography. I find that flow branching occurs where the flow thins over steeper slopes and that the degree of flow branching, network connectivity, and longevity of flow segments all influence the final flow morphology. Furthermore, because channel networks govern the distribution of lava supply within a flow, changes in the channel topology can dramatically alter the effective volumetric flux in any one branch, which affects both flow length and advance rate. Specifically, branching will slow and shorten flows, while merging can accelerate and lengthen them. To test these observations from historic eruptions and morphologic analysis, I use analogue experiments to simulate the interaction of a lava flow with a topographic obstacle and determine the conditions under which the flow branches and the effects of the bifurcation on flow advance rate. These experiments support the earlier results but also demonstrate the importance of flow dynamics and obstacle morphology on governing when flows may overtop obstacles. Consideration of channel networks is thus important for predicting lava flow behavior and mitigating flow hazards with diversion barriers.
One video of Kilauea lava flow activity from 2003-2010 accompanies this dissertation as a supplemental file.
This dissertation includes both previously published and unpublished co-authored material.
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Jiménez, de Contreras Diana Elizabeth. « Hazard Assessment and Risk Management at San Miguel volcano, El Salvador ». Doctoral thesis, Universitat de Barcelona, 2019. http://hdl.handle.net/10803/668457.
Texte intégralRésumé :
The purpose of this PhD thesis is to evaluate the volcanic risk associated with San Miguel Volcano, one of the most active volcanoes of El Salvador, through assessing volcanic hazard, that is, identify how a volcanic system (i.e., an active volcano or volcanic area) has behaved in the past and then use this information to infer how it may behave in the future. This task requires a compilation of all existing geological and geophysical information concerning the eruption style of the volcanic system in question, its eruptive recurrence, the structural constraints on the opening of new vents, and the characteristics and potential extent of its main hazards. The next step is to draw up eruption scenarios and hazard maps using the information gathered of the previous stage, which will constitute the basis for estimating exposure and vulnerability analysis, the third objective of this study.
We followed a probabilistic methodology to conduct the volcanic hazard assessment and scenario simulations. Probabilistic models are widely used in volcanic hazard assessment due to: (1) the lack of precise knowledge of the physical processes governing the dynamics of most volcanic hazards; (2) the difficulties in getting complete parameterisation sets for each phenomena; (3) the normally short time and computational costs; and (4) the acceptable results that probabilistic models provide. Thus, probabilistic or stochastic volcanic hazard analyses provide probabilistic outcomes that reflect the degree of uncertainty in the simulation.
We conducted the first systematic and comprehensive long-term hazard assessment for San Miguel using available geological data, past eruption records, stratigraphic information, and volcano-structural data, as well as new information gathered from fieldwork. We obtain a susceptibility map of the volcano and highlighted the areas with the greatest likelihood of hosting future eruptive vents. We conducted two temporal analyses, one with a forecasting time window of two years using information on volcanic activity over the past 430 years (historical period), and another with a forecasting window of six months, with information from the past 16 years (monitoring period). Then we calculated the most likely scenarios for each specific time windows. Secondly, we simulated: (1) the five most likely scenarios (ashfall scenarios, shortmedium extent, and VEI 1-2); (2) other probable scenarios related to lava flows, both according to its historical record; (3) other possible scenarios related to PDCs with similar characteristics to those that occurred during its geological history; and (4) the most hazardous scenario (ashfall, lava flow, PDC) also deduced from its geological record. We also constructed a qualitative integrated volcanic hazard map through the combination of the simulated scenarios.
Finally, we made an exposure analysis of San Miguel volcano area, considering population distribution, land use, as well as the distribution of the main infrastructures of the area. Moreover, we estimated a Vulnerability Index for the hazardous areas based on the characterization of the construction materials of walls and roofs of stocks. We constructed different exposure maps for 1) Population, 2) land use, 3) road network, 4) schools, and 5) health centers. For private houses and public infrastructures, we made an estimation of the Vulnerability Index in a village where lahars are frequent. This study was developed with the aim of improving land use and the already existing emergency plans, and pretends to be the starting point for the collaboration and coordination between scientists, the national observatory (OA-MARN), and the civil protection agency of San Miguel municipality, thus helping to strength this cooperation to face future volcanic crises related to San Miguel volcano.
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Weit, Anne. « Etude expérimentale de la concentration de particules solides dans les écoulements volcaniques biphasés turbulents ». Thesis, Université Clermont Auvergne (2017-2020), 2018. http://www.theses.fr/2018CLFAC060.
Texte intégralRésumé :
Des mélanges de gaz et de particules sont présents dans divers environnements géophysiques. De tels mélanges chauds sont générés par des éruptions volcaniques explosives et comprennent des écoulements de conduit, des jets et des panaches, ainsi que des courants de densité pyroclastiques. La concentration de particules dans ces mélanges volcaniques peut varier fortement, allant de concentrations élevées (>50 % en volume) dans les écoulements denses fluidisés à des concentrations très faibles dans les suspensions diluées dans lesquelles les particules sont mises en suspension par la phase gazeuse turbulente. Une limite de concentration inférieure à ~% en volume dans les suspensions diluées a été suggérée par des études récentes, car des concentrations plus élevées nécessiteraient une énergie cinétique turbulente excessive. L'objectif principal de cette thèse est d'étudier expérimentalement le comportement d'un écoulement d'air turbulent dans un cylindre avec des concentrations de particules croissantes, pour différents nombres de Reynolds et en utilisant différents types de particules. Les nombres de Reynolds des mélanges gaz-particules dans les expériences atteignaient ~106. Une première série d'expériences a été menée avec des billes de verre de différentes tailles allant de 75-80 μm jusqu'à 2 mm, pour un total de huit tailles de particules. Au-dessus d'un seuil de concentration moyenne de 0.5-3 % en volume, qui augmentait avec le nombre de Reynolds, le comportement de l'écoulement a montré une transition d'une suspension homogène de particules (sous la concentration maximale) vers une séparation en une partie basale dense et une partie supérieure diluée contenant la concentration maximale des particules. Ce seuil de concentration a été détecté à l'aide de mesures de pression et d'une méthode impliquant une sphère dont la densité était légèrement inférieure à la densité apparente des particules et qui pouvait donc flotter au-dessus de la partie basale dense, si celle-ci était présente. Des vidéos à haute vitesse ont révélé que l'apparition de la concentration maximale de particules coïncidait avec l'émergence d’amas de particules dans la partie turbulente diluée. Dans une deuxième partie de la thèse, les expériences ont été répétées pour cinq gammes de tailles de particules de céramique et elles ont révélé le même comportement général que pour les billes de verre. Pour les deux types de particules, une concentration maximale a pu être détectée pour presque toutes les tailles de particules et a montré une augmentation avec le nombre de Reynolds à la puissance 1/5 (billes de verre) ou 0.4 (billes de céramique). Compte tenu du nombre de Reynolds des particules, la concentration maximale des particules augmente ensuite jusqu'à la puissance de 1/6 pour les particules de céramique et de verre. Ces résultats ouvrent de nouvelles perspectives sur la structure des mélanges gaz-particules volcaniques et ils fournissent également des contraintes pour les données d'entrée et de sortie des simulations numériques et pour les observations géophysiquesMixtures consisting of gas and particles can be found in various geophysical environments. Hot mixtures are generated by explosive volcanic eruptions and include conduit flows, jets and buoyant plumes, and pyroclastic density currents. The particle concentration within these volcanic mixtures can vary highly, from high concentrations (>50 vol. %) in dense fluidized flows to very low concentrations in dilute suspensions in which the particles are suspended by the turbulent gas phase. A concentration limit of less than ~1 vol. % in dilute suspensions was suggested by recent studies, as higher concentrations would require excessive turbulent kinetic energy. The main objective of this thesis was to investigate experimentally the behavior of a turbulent air flow in a pipe with increasing particle concentrations, for different Reynolds numbers and using different types of particles. The Reynolds numbers of the gas-particle mixtures in the experiments were up to ~106. A first set of experiments was conducted with glass beads of varying sizes from 75-80 μm up to 2 mm, for eight particle size ranges in total. Above a bulk concentration threshold of ~0.5-3 vol. %, which increased with the Reynolds number, the flow behavior changed from a homogeneous suspension of particles (below the maximum concentration) to a separation into a dense basal part and an upper dilute part carrying the maximum concentration of particles. This concentration threshold was detected with pressure measurements and a method that involved a ball of a slightly lower density than the bulk density of the particles, which could thus float over the dense basal part, if present. High-speed videos revealed that the occurrence of the maximum particle concentration coincided with the emergence of particle clusters in the dilute turbulent part. In a second part of the thesis, the experiments were repeated for five ceramic particle size ranges and they yielded the same general behavior as for the glass beads. For both types of particles, a maximum concentration could be detected for almost all particle size ranges and showed an increase with the mixture Reynolds number to the power 1/5 (glass beads) or 0.4 (ceramic beads). Considering the particle Reynolds number the maximum particle concentration then increase to the power 1/6 for both ceramic and glass particles. These results give new insights about the structure of volcanic gas-particle mixtures and they also provide constraints for input and output data of numerical simulations and for geophysical observations
Livres sur le sujet "Experimental volcanology"
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United States. National Aeronautics and Space Administration., dir. Experimental study of lunar and SNC magmas : Final report, NASA grant NAGW-3633, 4/1/93 to 3/31/97. [Washington, DC : National Aeronautics and Space Administration, 1998.
Trouver le texte intégralChapitres de livres sur le sujet "Experimental volcanology"
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Martel, C., R. A. Brooker, J. Andújar, M. Pichavant, B. Scaillet et J. D. Blundy. « Experimental Simulations of Magma Storage and Ascent ». Dans Advances in Volcanology, 101–10. Cham : Springer International Publishing, 2017. http://dx.doi.org/10.1007/11157_2017_20.
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Pichavant, M., N. Le Gall et B. Scaillet. « Gases as Precursory Signals : Experimental Simulations, New Concepts and Models of Magma Degassing ». Dans Advances in Volcanology, 139–54. Cham : Springer International Publishing, 2018. http://dx.doi.org/10.1007/11157_2018_35.
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Sweeney, R. J., T. J. Falloon et D. H. Green. « Experimental Constraints on the Possible Mantle Origin of Natrocarbonatite ». Dans IAVCEI Proceedings in Volcanology, 191–207. Berlin, Heidelberg : Springer Berlin Heidelberg, 1995. http://dx.doi.org/10.1007/978-3-642-79182-6_14.
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Brivio, P. A., E. Lo Giudice et E. Zilioli. « Thermal Infrared Surveys at Vulcano Island : An Experimental Approach to the Thermal Monitoring of Volcanoes ». Dans IAVCEI Proceedings in Volcanology, 357–71. Berlin, Heidelberg : Springer Berlin Heidelberg, 1989. http://dx.doi.org/10.1007/978-3-642-73759-6_21.
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Canbolat, Serhat. « Experimental and Visual Assessments of Artificially/Naturally Fractured Cores During Improved Oil Recovery ». Dans Recent Research on Sedimentology, Stratigraphy, Paleontology, Tectonics, Geochemistry, Volcanology and Petroleum Geology, 201–4. Cham : Springer Nature Switzerland, 2023. http://dx.doi.org/10.1007/978-3-031-43222-4_44.
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Kjarsgaard, B. A., D. L. Hamilton et T. D. Peterson. « Peralkaline Nephelinite/Carbonatite Liquid Immiscibility : Comparison of Phase Compositions in Experiments and Natural Lavas from Oldoinyo Lengai ». Dans IAVCEI Proceedings in Volcanology, 163–90. Berlin, Heidelberg : Springer Berlin Heidelberg, 1995. http://dx.doi.org/10.1007/978-3-642-79182-6_13.
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Gasparini, Paolo, Roberto Scarpa et Keiiti Aki. « Preliminary Results from a Field Experiment on Volcanic Events at Kilauea Using an Array of Digital Seismographs ». Dans IAVCEI Proceedings in Volcanology, 168–89. Berlin, Heidelberg : Springer Berlin Heidelberg, 1992. http://dx.doi.org/10.1007/978-3-642-77008-1_13.
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Kamo, K., et K. Ishihara. « A Preliminary Experiment on Automated Judgement of the Stages of Eruptive Activity Using Tiltmeter Records at Sakurajima, Japan ». Dans IAVCEI Proceedings in Volcanology, 585–98. Berlin, Heidelberg : Springer Berlin Heidelberg, 1989. http://dx.doi.org/10.1007/978-3-642-73759-6_35.
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Dioguardi, Fabio, Tobias Dürig, Samantha L. Engwell, Magnus T. Gudmundsson et Susan C. Loughlin. « Investigating Source Conditions and Controlling Parameters of Explosive Eruptions : Some Experimental-Observational- Modelling Case Studies ». Dans Updates in Volcanology - From Volcano Modelling to Volcano Geology. InTech, 2016. http://dx.doi.org/10.5772/63422.
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Deamer, David W. « Hydrothermal Conditions are Conducive for the Origin of Life ». Dans Assembling Life. Oxford University Press, 2019. http://dx.doi.org/10.1093/oso/9780190646387.003.0008.
Texte intégralRésumé :
Alexander Ivanovich Oparin was first to consider the origin of life in strictly scientific terms. Oparin published The Origin of Life in 1924, in his native Russian language, and was active in the field for the next 50 years. During my initial field work in the volcanic regions of Kamchatka, organized with Vladimir Kompanichenko, we visited the Institute of Volcanology and Seismology in Petropavlovsk, and I happened to see the above quote painted on a wall near the entrance. Oparin’s proposal about how life can begin was intuitive because he had no experimental evidence as a foundation, but as our party rode in helicopters up and down the peninsula from one volcanic site to the next, I began to share his intuition. The focus of this chapter concerns the properties of water in contact with mineral surfaces heated by volcanism, inspired by what we saw in Kamchatka. Four billion years ago, as the global temperature decreased following the condensation of the ocean, there came a point at which the components required for the origin of life could assemble into systems of encapsulated polymers. Two alternative hydrothermal conditions have been proposed as sites where this could have occurred: salty seawater at submarine hydrothermal vents and freshwater circulating in hydrothermal fields associated with volcanic land masses. To weigh the alternatives, this chapter considers the chemical and physical properties of hydrothermal vents and hydrothermal fields and how each could contribute to the origin of cellular life. Questions to be addressed: What are the chemical and physical properties of hydrothermal vents? How do the properties of hydrothermal fields differ from those of vents? How are these properties related to the way that organic solutes can undergo physical and chemical interactions related to the origin of life? Suppose that an organic chemist decides to synthesize a new compound that involves making an ester bond. The chemist is provided with a solution of the two reactants such as acetic acid and ethanol, and then is given a choice: should the reaction be run in an ice bath or instead heated to boiling and refluxed?
Actes de conférences sur le sujet "Experimental volcanology"
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Dingwell, Donald B. « ARTHUR L. DAY MEDAL : EXPERIMENTAL VOLCANOLOGY : ACCESSING THE INACCESSIBLE ». Dans GSA Annual Meeting in Denver, Colorado, USA - 2016. Geological Society of America, 2016. http://dx.doi.org/10.1130/abs/2016am-276870.
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