Articles de revues : « Experimental volcanism »

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Pawley, A. R., et J. R. Holloway. « Water Sources for Subduction Zone Volcanism : New Experimental Constraints ». Science 260, n^o 5108 (30 avril 1993) : 664–67. http://dx.doi.org/10.1126/science.260.5108.664.

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Scheu, Bettina, Oliver Spieler et Donald B. Dingwell. « Dynamics of explosive volcanism at Unzen volcano : an experimental contribution ». Bulletin of Volcanology 69, n^o 2 (11 mai 2006) : 175–87. http://dx.doi.org/10.1007/s00445-006-0066-5.

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Pralle, Norbert, Michael Külzer et Gerd Gudehus. « Experimental evidence on the role of gas in sediment liquefaction and mud volcanism ». Geological Society, London, Special Publications 216, n^o 1 (2003) : 159–71. http://dx.doi.org/10.1144/gsl.sp.2003.216.01.11.

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Dingwell, Donald B. « Recent experimental progress in the physical description of silicic magma relevant to explosive volcanism ». Geological Society, London, Special Publications 145, n^o 1 (1998) : 9–26. http://dx.doi.org/10.1144/gsl.sp.1996.145.01.02.

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Righter, K., K. Pando et L. R. Danielson. « Experimental evidence for sulfur-rich martian magmas : Implications for volcanism and surficial sulfur sources ». Earth and Planetary Science Letters 288, n^o 1-2 (30 octobre 2009) : 235–43. http://dx.doi.org/10.1016/j.epsl.2009.09.027.

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Le Corvec, Nicolas, Thierry Menand et Jan Lindsay. « Interaction of ascending magma with pre-existing crustal fractures in monogenetic basaltic volcanism : an experimental approach ». Journal of Geophysical Research : Solid Earth 118, n^o 3 (mars 2013) : 968–84. http://dx.doi.org/10.1002/jgrb.50142.

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Marzano, Frank S., Errico Picciotti, Mario Montopoli et Gianfranco Vulpiani. « Inside Volcanic Clouds : Remote Sensing of Ash Plumes Using Microwave Weather Radars ». Bulletin of the American Meteorological Society 94, n^o 10 (1 octobre 2013) : 1567–86. http://dx.doi.org/10.1175/bams-d-11-00160.1.

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Microphysical and dynamical features of volcanic tephra due to Plinian and sub-Plinian eruptions can be quantitatively monitored by using ground-based microwave weather radars. The methodological rationale and unique potential of this remote-sensing technique are illustrated and discussed. Volume data, acquired by ground-based weather radars, are processed to automatically classify and estimate ash particle concentration and fallout. The physical– statistical retrieval algorithm is based on a backscattering microphysical model of fine, coarse, and lapilli ash particles, used within a Bayesian classification and optimal estimation methodology. The experimental evidence of the usefulness and limitations of radar acquisitions for volcanic ash monitoring is supported by describing several case studies of volcanic eruptions all over the world. The radar sensitivity due to the distance and the system noise, as well as the various radar bands and configurations (i.e., Doppler and dual polarized), are taken into account. The discussed examples of radar-derived ash concentrations refer to the case studies of the Augustine volcano eruption in 2002, observed in Alaska by an S-band radar; the Grímsvötn volcano eruptions in 2004 and 2011, observed in Iceland by C- and X-band weather radars and compared with in situ samples; and the Mount Etna volcano eruption in 2011, observed by an X-band polarimetric radar. These applications demonstrate the variety of radar-based products that can be derived and exploited for the study of explosive volcanism.

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Makongoro, Mohamed Zengo, Maheswara Rao Vegi, Said Ali Hamad Vuai et Michael Mwita Msabi. « Chronostratigraphic Studies of the Ootun Area Revealing the Late Holocene Plume Volcanism of the Oldoinyo Lengai, Ngorongoro, Tanzania ». Geofluids 2022 (5 septembre 2022) : 1–16. http://dx.doi.org/10.1155/2022/2429548.

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Oldoinyo Lengai has been a subject of international attention for geoscientists because of its uniqueness. The mountain is the world’s only active natrocarbonatite volcano whose recent activities are well documented. However, little is known about its eruptive history during the Holocene. One way of uncovering past volcanic activities is through chronostratigraphic studies. A rare stratigraphic sequence in the Ootun area containing buried tephra beds and paleosols is presented in this article. The beds suggest that the nearby active Oldoinyo Lengai volcano experienced the main plume volcanism during the late Holocene. This work presents the lithology of the area, estimated deposition period, and elemental and mineralogical compositions of strata, and establishing similarities between ash properties and information from previously reported chemistry and eruptions of the Oldoinyo Lengai volcano. Energy dispersive X-ray fluorescence, X-ray diffractometry, and accelerated mass spectrometry techniques were used for elemental, mineralogical, and radiocarbon dating analyses. A 1.3-m vertical soil profile revealed three major strata: topsoil, tephra bed, and paleosols. The paleosols are presumed to have been topsoil of the Ootun area during the Holocene. Subsurface tephra layers were found to contain similar properties to the volcanic material of the Oldoinyo Lengai. Based on the experimental findings and literature data, the study reports the occurrence of two major plume eruption events from the Oldoinyo Lengai, which happened around the minimum (oldest) age of 490 ± 10 BC and 771 AD. This work is essentially important in demonstrating the relevance of the region’s tephra chronostratigraphic studies by revealing the prospect of collecting additional scientific data on past geological processes and paleoenvironmental conditions of northern Tanzania.

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ZANON, VITTORIO. « Geology and volcanology of San Venanzo volcanic field (Umbria, Central Italy) ». Geological Magazine 142, n^o 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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Whalen, J. B., A. Zagorevski, V. J. McNicoll et N. Rogers. « Geochemistry, U–Pb geochronology, and genesis of granitoid clasts in transported volcanogenic massive sulfide ore deposits, Buchans, Newfoundland ». Canadian Journal of Earth Sciences 50, n^o 11 (novembre 2013) : 1116–33. http://dx.doi.org/10.1139/cjes-2013-0040.

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The Buchans Group, central Newfoundland, represents an Ordovician continental bimodal calc-alkaline arc sequence that hosts numerous volcanogenic massive sulfide (VMS) occurrences, including both in situ and mechanically transported sulfide breccia–conglomerate orebodies. Diverse lithic clasts associated with transported deposits include rounded granitoid clasts. Earlier workers have suggested that Buchans Group VMS-hosting felsic extrusive units, small granodiorite intrusions (e.g., Wiley’s Brook), and granitoid cobbles associated with transported ore represent co-genetic products of the same magmatic system. The granitoid cobbles and small granodiorite intrusions are geochemically similar and closely resemble Buchans Group felsic volcanic units. U–Pb zircon age determinations show a (i) 466.7 ± 0.5 Ma crystallization age for the Wiley’s Brook granodiorite (WBG), (ii) 464 ± 4 Ma crystallization age for a granitoid cobble, and (iii) 466 ± 4 Ma maximum deposition age for a conglomerate–sandstone sequence associated with transported ore. Thus, Buchans Group felsic plutonic rocks are within experimental error of felsic volcanism and VMS deposition. Furthermore, εNd (T) (T, time of crystallization) values of four granitoid cobbles (–1.95 to –4.0) overlap values obtained from Buchans Group felsic volcanic units. Our results are compatible with plutonic and volcanic rocks being related through fractional crystallization or partial melting processes but do not support a petrogenetic link between VMS deposition and exposed felsic plutons. Comparisons to modern arc analogues favour exhumation of plutonic rocks by extension along caldera or rift walls and (or) subaerial erosion. Enigmatic rounding of Buchans granitoid clasts was likely accomplished in a subaerial or shallow marine environment, and the clasts transported into a VMS-active basin by mass flows.

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Fox, Stefan, Annika Gspandl et Franziska M. Wenng. « Acceleration of amino acid racemization by isovaline : possible implications for homochirality and biosignature search ». International Journal of Astrobiology 19, n^o 3 (9 mars 2020) : 276–82. http://dx.doi.org/10.1017/s1473550420000014.

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AbstractIn nature, abiotically formed amino acids are usually racemic. However, this is not true for the α,α-dialkyl amino acid isovaline (Iva), which has an L-enantiomeric excess in some specimens of carbonaceous meteorites. On the early Earth and Mars, such meteorites were sources of amino acids, including Iva. Therefore, a connection may exist between the possible chiral influence of non-racemic Iva and the origin of biological homochirality. On the surface of a young terrestrial planet, amino acids can be chemically altered in many ways. For example, high temperatures from geothermal heating can lead to racemization. Four billion years ago, active volcanism and volcanic islands provided suitable conditions for such reactions and perhaps even for early microbial life on Earth. In the current study, we investigated the influence of D- and L-Iva on the thermal racemization of L-alanine (L-Ala) and L-2-aminobutyric acid (L-Abu) in a simulated hot volcanic environment. The amino acids were intercalated in the clay mineral calcium montmorillonite (SAz-1). While Iva was resistant to racemization, partial racemization was observed for Ala and Abu after 8 weeks at 150°C. The experimental results – for example, accelerated racemization in the presence of Iva and different influences of the Iva enantiomers – suggest that the amino acid molecules interacted with each other, possibly in hydrogen-bonded dimers. Accelerated racemization of amino acids could have been an obstacle to the development of homochirality. Besides, it is also detrimental to the use of homochirality as a biosignature, for example, in the search for microbial life on Mars.

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Martín, Domingo A., Jorge L. Costafreda, Leticia Presa, Elena Crespo, José Luis Parra, Beatriz Astudillo et Miguel Ángel Sanjuán. « Ignimbrites Related to Neogene Volcanism in the Southeast of the Iberian Peninsula : An Experimental Study to Establish Their Pozzolanic Character ». Materials 16, n^o 4 (13 février 2023) : 1546. http://dx.doi.org/10.3390/ma16041546.

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The speed at which climate change is happening is leading to a demand for new pozzolanic materials that improve the quality of cements and, at the same time, limit the emission of greenhouse gases into the atmosphere. The main objective of this work is the detailed characterization of an ignimbrite sample (IGNS) to demonstrate its effectiveness as a natural pozzolan. To meet this objective, a series of tests were carried out. In the first stage, mineral and chemical analyses were performed, such as petrographic analysis by thin section (TSP), X-ray diffraction (XRD), oriented aggregate (OA), scanning electron microscopy (SEM) and X-ray fluorescence (XRF). In the second stage, the following technical tests were carried out: chemical quality analysis (QCA), pozzolanicity test (PT) and mechanical compressive strength (MS) at 7, 28 and 90 days, using mortar specimens with ignimbrite/cement formulation (IGNS/PC): 10, 25 and 40% to establish the pozzolanic nature of the ignimbrite. The results of the mineral and chemical analyses showed that the sample has a complex mineralogical constitution, consisting of biotite mica, potassium feldspar, plagioclase, smectite (montmorillonite), quartz, volcanic glass, iron, titanium and manganese oxides, chlorite and chlorapatite. On the other hand, the technological tests revealed the pozzolanic nature of the sample, as well as visible increases in the mechanical compressive strengths in the three proportions, the most effective being IGNS/PC:10% and IGNS/PC:25% at 7, 28 and 90 days of setting. The results obtained could be applied in the formulation of new pozzolanic cements with ignimbrite as a natural pozzolanic aggregate.

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Izzah Salsabila, Tasyania, Alfyananda Kurnia Putra et Teresa Matos. « Mobile Virtual Field Trip and Geography Education : Potential Exploration of Complex Problem Solving and Spatial Intelligence Capabilities ». International Journal of Interactive Mobile Technologies (iJIM) 16, n^o 24 (20 décembre 2022) : 21–31. http://dx.doi.org/10.3991/ijim.v16i24.36157.

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This study aims to determine the effect of M-VGFT media on students' Complex Problem Solving and Spatial Intelligence abilities. Quasi-experimental research with post-test-only group design method. The design used two experimental groups with a purposive or judgment sampling method considering the average class value. X.2 Social Science group (14 boys and 20 girls), X.3 Social Science group (17 boys and 17 girls), and X.4 Social Science (17 boys and 17 girls). The subjects of this study were first-year high school students in the even semester of the 2021/2022 academic year. Hypothesis testing using independent sample t-test to determine the effect of M-VGFT media on the ability of students' Complex Problem Solving and Spatial Intelligence in the subject of Geography on Volcanism. The results showed a significant influence between M-VGFT media on students' Complex Problem Solving Ability and Spatial Intelligence in Madrasah Aliah Negeri Baru. However, there are differences in the influence between male and female students on the two variables.

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Bains, William, Janusz Jurand Petkowski, Zhuchang Zhan et Sara Seager. « A Data Resource for Prediction of Gas-Phase Thermodynamic Properties of Small Molecules ». Data 7, n^o 3 (11 mars 2022) : 33. http://dx.doi.org/10.3390/data7030033.

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The thermodynamic properties of a substance are key to predicting its behavior in physical and chemical systems. Specifically, the enthalpy of formation and entropy of a substance can be used to predict whether reactions involving that substance will proceed spontaneously under conditions of constant temperature and pressure, and if they do, what the heat and work yield of those reactions would be. Prediction of enthalpy and entropy of substances is therefore of value for substances for which those parameters have not been experimentally measured. We developed a database of 2869 experimental values of enthalpy of formation and 1403 values for entropy for substances composed of stable small molecules, derived from the literature. We developed a model for predicting enthalpy of formation and entropy from semiempirical quantum mechanical calculations of energy and atom counts, and applied the model to a comprehensive database of 16,417 small molecules. The database of small-molecule thermodynamic properties will be useful for predicting the outcome of any process that might involve the generation or destruction of volatile products, such as atmospheric chemistry, volcanism, or waste pyrolysis. Additionally, the collected experimental thermodynamic values will be of value to others developing models to predict enthalpy and entropy.

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Maharramova, M. Ya, I. S. Guliyev, A. B. Huseynov et E. B. Zeynalov. « Carbonic nanostructures in subsurface rocks : problem review Part II. Graphene, carbonic nanotubes, nanofibers ». Azerbaijan Oil Industry, n^o 9 (15 septembre 2020) : 22–31. http://dx.doi.org/10.37474/0365-8554/2020-9-22-31.

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The paper reviews the publications on the search and exploration of carbonic nanotubes and other nanocarbonic structures in subsurface rocks. It is shown that the graphenes and carbonic nanotubes (CNT) exist in the composition of various magmatic and sedimentary rocks. They are formed in the graphite globules of volcanic rocks, as well as in the sediments, where the pressure, the particles of metallic catalysts, the tension stresses and time factors in million years compensate the absence of high temperatures. Experimental laboratory modeling of natural processes has been carried out and the reality of formation of carbonic nanostructures during the pyrolysis of volcanic gases on the lava catalysts, mechanical activation and processing of amorphous carbon or bituminous coal shown. Principal possibility of realization of technology of CNT mass production via pyrolysis of hydrocarbon crude material in the presence of different catalytically-active natural minerals has been reviewed and proven. The analysis of the aspects following the activity of mud volcanoes shows that there are all suppositions for the formation of carbonic nanostructures: the pressure bump of deep rocks out of the hot eruptive centre, methane as carbonic crude, catalytically-active breccias containing transition metals and their oxides, the process of methane burning in the medium poor of oxygen. However, it is not yet absolutely clear. As a working hypothesis we propose a model of formation of these structures due to the mud volcanism activity in the reactions of methane flow, the catalysts in which natural minerals exist. In such processes as a result of intensive methane flow, there occur negative pressure values and cavitation effects in the presence of which local temperature and pressure increase efficient for formation of adamantine and nanosize carbonic structures take place. In case if this mechanism is real, the studies point to a perspective of obtaining valuable products in conditions of natural geological processes. There are no messages or publications yet on the exploration of carbonic nanostructures in the rocks of mud volcanoes.

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Niemeier, Ulrike, Felix Riede et Claudia Timmreck. « Simulation of ash clouds after a Laacher See-type eruption ». Climate of the Past 17, n^o 2 (11 mars 2021) : 633–52. http://dx.doi.org/10.5194/cp-17-633-2021.

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Abstract. Dated to approximately 13 000 years ago, the Laacher See (East Eifel volcanic zone) eruption was one of the largest midlatitude Northern Hemisphere volcanic events of the Late Pleistocene. This eruptive event not only impacted local environments and human communities but probably also affected Northern Hemispheric climate. To better understand the impact of a Laacher See-type eruption on NH circulation and climate, we have simulated the evolution of its fine ash and sulfur cloud with an interactive stratospheric aerosol model. Our experiments are based around a central estimate for the Laacher See aerosol cloud of 15 Tg of sulfur dioxide (SO2) and 150 Tg of fine ash, across the main eruptive phases in May and a smaller one in June with 5 Tg SO2 and 50 Tg of fine ash. Additional sensitivity experiments reflect the estimated range of uncertainty of the injection rate and altitude and assess how the solar-absorptive heating from the fine ash emitted in the first eruptive phase changed the volcanic clouds' dispersion. The chosen eruption dates were determined by the stratospheric wind fields to reflect the empirically observed ash lobes as derived from geological, paleoecological and archeological evidence linked directly to the prehistoric Laacher See eruption. Whilst our simulations are based on present-day conditions, and we do not seek to replicate the climate conditions that prevailed 13 000 years ago, we consider our experimental design to be a reasonable approximation of the transport pathways in the midlatitude stratosphere at this time of year. Our simulations suggest that the heating of the ash plays an important role for the transport of ash and sulfate. Depending on the altitude of the injection, the simulated volcanic cloud begins to rotate 1 to 3 d after the eruption. This mesocyclone, as well as the additional radiative heating of the fine ash, then changes the dispersion of the cloud itself to be more southward compared to dispersal estimated without fine ash heating. This ash-cloud-generated southerly migration process may at least partially explain why, as yet, no Laacher See tephra has been found in Greenland ice cores. Sulfate transport is similarly impacted by the heating of the ash, resulting in stronger transport to low latitudes, later arrival of the volcanic cloud in the Arctic regions and a longer lifetime compared to cases without injection of fine ash. Our study offers new insights into the dispersion of volcanic clouds in midlatitudes and addresses a likely behavior of the ash cloud of the Laacher See eruption that darkened European skies at the end of the Pleistocene. In turn, this study can also serve as significant input for scenarios that consider the risks associated with re-awakened volcanism in the Eifel.

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Hernández-Uribe, David, Juan David Hernández-Montenegro, Kim A. Cone et Richard M. Palin. « Oceanic slab-top melting during subduction : Implications for trace-element recycling and adakite petrogenesis ». Geology 48, n^o 3 (9 décembre 2019) : 216–20. http://dx.doi.org/10.1130/g46835.1.

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Abstract Arc volcanism and trace-element recycling are controlled by the devolatilization of oceanic crust during subduction. The type of fluid—either aqueous fluids or hydrous melts—released during subduction is controlled by the thermal structure of the subduction zone. Recent thermomechanical models and results from experimental petrology argue that slab melting occurs in almost all subduction zones, although this is not completely supported by the rock record. Here we show via phase equilibrium modeling that melting of either fresh or hydrothermally altered basalt rarely occurs during subduction, even at water-saturated conditions. Melting occurs only along the hottest slab-top geotherms, with aqueous fluids being released in the forearc region and anatexis restricted to subarc depths, leading to high-SiO2 adakitic magmatism. We posit that aqueous fluids and hydrous melts preferentially enhance chemical recycling in “hot” subduction zones. Our models show that subducted hydrothermally altered basalt is more fertile than pristine basaltic crust, enhancing fluid and melt production during subduction and leading to a greater degree of chemical recycling. In this contribution, we put forward a petrological model to explain (the lack of) melting during the subduction of oceanic crust and suggest that many large-scale models of mass transfer between Earth’s surface and interior may require revision.

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Nikolaev, I. Yu, T. K. Burakhovych, A. M. Kushnir et Ye M. Sheremet. « Geoelectric heterogeneities of the Kerch iron ore basin ». Geofizicheskiy Zhurnal 43, n^o 5 (24 novembre 2021) : 165–80. http://dx.doi.org/10.24028/gzh.v43i5.244078.

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The three-dimensional geoelectric model of the Earth’s crust and upper mantle of the Kerch Peninsula has been built for the first time based on the results of experimental observations of the Earth’s low-frequency electromagnetic field, carried out in 2007—2013 by the Institutes of the National Academy of Sciences of Ukraine. Its physical and geological interpretation and detailing of the near-surface part were carried out according to the data of the audiomagnetotelluric sounding method to study the deep structure of the Kerch iron ore basin. To the east of the Korsak-Feodosiya fault along the southern part of the Indolo-Kuban trough (in the north of the South Kerch and almost under the entire North Kerch zones), a low-resistance anomaly (ρ=1 Ohm∙m) was found at depths from 2.5 km to 12 km about 20 km wide. Its eastern part is located in the consolidated Earth’s crust and is galvanically connected with surface sedimentary strata, while the western part is completely in sedimentary deposits. The anomaly covers the territory of the Kerch iron ore basin and occurrences of mud volcanism. The characteristics of the upper part of the layered section of the Kerch Peninsula in the interval of the first hundreds of meters were obtained from the results of one-dimensional inversion of the audiomagnetotelluric sounding data (frequency range 8—4000 Hz). It is shown that the first 15 m of the section, corresponding to Quaternary deposits, have resistivity values up to 1 Ohm∙m. Below, in the Neogene sediments, the electrical resistance increases to values of 5 Ohm∙m and more. Both horizontally and vertically, the distribution of resistivity values has a variable character, manifesting as a thin-layered structure with low resistivity values. Possibly, such areas have a direct connection with the channel for transporting hummock material and gases. A connection is assumed between the low-resistivity thin-layered near-surface areas, a deep anomaly of electrical conductivity in the upper part of the Earth’s crust, and the likely high electrical conductivity of rocks at the depths of the upper mantle with iron ore deposits, as well as the manifestation of mud volcanism. The heterogeneity of the crustal and mantle highly conductive layers may indicate a high permeability of the contact zones for deep fluids.

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Kassaras, I., F. Louis, A. Magganas, K. Makropoulos et G. Kaviris. « Anelasticity beneath the Aegean inferred from Rayleigh wave attenuation ». Bulletin of the Geological Society of Greece 40, n^o 3 (5 juin 2018) : 1103. http://dx.doi.org/10.12681/bgsg.16829.

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Anelasticity of the Earth crucially affects the propagation of seismic waves especially, in the long period range. However, even though the elastic properties of the Aegean deep lithosphère and upper mantle have been thoroughly investigated, their quantitative anelastic properties that influence the long period wavefield are still largely unknown. This work is towards contributing to the better knowledge of the deep structure of the Aegean by introducing experimental anelastic parameters via the study of long period Rayleigh waves attenuation. For this scope, fundamental mode attenuation coefficients (γ%) have been obtained for different two-station great-circle paths across the Aegean. The data used were provided by a broadband array installed in the area for 6 months in 1997. More than 1100 seismograms were analyzed in the 10-100 s range to obtain 17 sets of path average γR(T) functions. The attenuation coefficients are in the range 2.5*10~3 — 0.15 x 10' km' and correlate sufficiently with both experimental measurements in active tectonic regions elsewhere and synthetics generated with the use of an attenuation reference model inferred from other sources. By applying a stochastic uncoupled causal inversion method an average joint Qß'1 and shear velocity model representative of the under study area was obtained. Furthermore, path average JR(T) functions were combined in a continuous regionalization tomographic scheme to obtain local yR(T) and tomograms were constructed in the range 10-60 s. The most prominent feature in the tomograms is a high attenuation region in the central and north Aegean. This region is located south of the North Anatolian Trough and correlates well with a low shear velocity zone inferred from surface wave phase velocities. Moreover, it is associated with observed intense extensional deformation rates, mantle olivine anisotropy, recent volcanism and high heat flow.

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Coenraads, Robert R., F. Lin Sutherland et Peter D. Kinny. « The origin of sapphires : U–Pb dating of zircon inclusions sheds new light ». Mineralogical Magazine 54, n^o 374 (mars 1990) : 113–22. http://dx.doi.org/10.1180/minmag.1990.054.374.13.

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AbstractUranium-lead isotope dating of two zircon inclusions in sapphires from the Central Province, NSW. gives ages of 35.9 ± 1.9 and 33.7 ± 2.1 million years (Ma). These ages fall within the range of basalt potassium-argon ages of 19 to 38Ma and zircon fission track ages of 2 to 49Ma for the timing of volcanism of the Central Province, NSW. These data, combined with the observation that corundum is found associated with many alkali basaltic provinces, indicate a genetic link between the growth of large corundum crystals and the processes involved in alkali basaltic magma generation. The reported failure of experimental attempts to grow corundum from a corundum-bearing basaltic composition, and more significantly, the abundance of incompatible elements such as U, Th, Zr, Nb and Ta in inclusion minerals indicate that the crystallization process is not simple. Corundum and the other minerals found as its inclusions (zircon, columbite, thorite, uranium pyrochlore, alkali feldspar etc.) could not have crystallized from most basaltic compositions. A more complex process must occur in which crystallization takes place when there are high proportions of incompatible elements and volatiles in the melt. These crystallization products are then carried to the surface by upward movement of later magmas. The extent of this process presumably determines whether a particular basaltic province carries sufficient corundum to be worked into economic concentrations of sapphire.

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Brugman, Karalee K., et Christy B. Till. « A low-aluminum clinopyroxene-liquid geothermometer for high-silica magmatic systems ». American Mineralogist 104, n^o 7 (1 juillet 2019) : 996–1004. http://dx.doi.org/10.2138/am-2019-6842.

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Abstract Several geothermobarometric tools have focused on clinopyroxene due to its prevalence in igneous rocks, however clinopyroxene produced in high-silica igneous systems is high in iron and low in aluminum, causing existing geothermometers that depend on aluminum exchange to fail or yield overestimated temperatures. Here we present a new clinopyroxene-liquid geothermometer recommended for use in natural igneous systems with bulk SiO2 ≥ 70 wt%, which contain clinopyroxene with Mg# ≤ 65 and Al2O3 ≤ 7 wt%. (1) T ( ∘ C ) = 300 [ − 1.89 − 0.601 ( X CaTs Cpx ) − 0.186 ( X DiHd 2003 Cpx ) + 4.71 ( X SiO 2 liq ) + 77.6 ( X TiO 2 liq ) + 10.9 ( X FeO liq ) + 33.6 ( X MgO liq ) + 15.5 ( X CaO liq ) + 15.6 ( X KO 0.5 liq ) ] The new geothermometer lowers calculated temperatures by ~85 °C on average relative to Putirka (2008, Eq. 33) and reduces the uncertainty by a factor of two (standard error of estimate ±20 °C). When applied to natural systems, we find this new clinopyroxene-liquid geothermometer reconciles many inconsistencies between experimental phase equilibria and preexisting geothermometry results for silicic volcanism, including those from the Bishop Tuff and Yellowstone caldera-forming and post-caldera rhyolites. We also demonstrate that clinopyroxene is not restricted to near-liquidus temperatures in rhyolitic systems; clinopyroxene can be stable over a broad temperature range, often down to the solidus. An Excel spreadsheet and Python notebook for calculating temperature with this new geothermometer may be downloaded from GitHub at http://bit.ly/cpxrhyotherm.

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Hakim, Erwin Hilman. « PEMANFAATAN FENOMENA ALAM GUNUNG GALUNGGUNG SEBAGAI SUMBER BELAJAR UNTUK MENGEMBANGKAN DAYA ANALISIS MAHASISWA GEOGRAFI ». NATURALISTIC : Jurnal Kajian Penelitian Pendidikan dan Pembelajaran 1, n^o 2 (17 avril 2017) : 186–92. http://dx.doi.org/10.35568/naturalistic.v1i2.6.

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Natural phenomena Mountain Galunggung learning resources in understanding the symptoms of volcanism, these phenomena can be used as a source of learning geography student to improve the analysis of their environment. Geography is a natural laboratory and a lot of geography materials that can not be understood simply by studying a concept in the literature book is done in space by verbalistis. This research was conducted at the Department of Geography Students of the Faculty of Education Siliwangi University. This study population Geography students the semester II of classes using model experiments with field studies and grade control using model lecture. Quantitative data analysis techniques using statistical methods, there are two statistical techniques used, namely descriptive statistics for the description of research data and statistical techniques t-test. There is a significant difference to the results of the test and development of power analysis geography student this is evidenced by the results of tests experimental minimum 13, maximum numbers 23, the range of values 10, a mean of 18.15, median 18.00. The test results control class minimum 10, maximum 20, the range of values 10, mean 15.39, median 15.00. Power analysis geography student experiment class has a depth analysis of the phenomena that is the result of data processing that students can open up and develop the power of analysis, the material is easy to understand, the students more active and interactive, while for the control class learning process is less effective without a concrete example to be analytical.

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Mart, Y. « The structural evolution of oceanic core complexes : A concept based on analog modeling ». Geodynamics & ; Tectonophysics 11, n^o 1 (19 mars 2020) : 1–15. http://dx.doi.org/10.5800/gt-2020-11-1-0458.

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Oceanic core complexes are lithological assemblages of predominantly peridotites and serpentinites, located along intersections of some slow-spreading oceanic accreting rifts and fracture zones, embedded in the predominantly basaltic oceanic lithosphere, and fresh and old basalts are juxtaposed across the fracture zone. Centrifuge-based experimental models indicated that subduction would initiate at sites where two lithospheric slabs are juxtaposed, provided that the density difference between them is at least 200 kg/m3 and the friction along their contact plane is low. It was discerned that the modeled underthrust denser lithosphere would reach the modeled asthenosphere and represent tectonic subduction. In many such occurrences, extension in the over-riding slab would develop normal faults that could be penetrated by the lighter fraction of the subducted slab, generating volcanism and diapirism. These experiments suggest further that since the density contrasts and the low friction constraints could be satisfied at the intersections of fracture zones and slow-spreading oceanic ridges, subduction could occur there too and not only along ocean-continent boundaries. Furthermore, since the thermal gradient in ridge-fracture zone intersections is very steep and volatiles in the underthrust slab abound in the subducted slab, a portion of the underthrust basalts would undergo serpentinization and another segment could become peridotitic. It is suggested further that the light serpentinite would ascend through the normal faults in the over-riding slab and reach the seafloor diapirically, carrying along large sections of peridotite, to produce the serpentinite-peridotite petrology that typifies oceanic core complex at junctions of fracture zones and slow spreading ridges.

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Gordienko, V. V. « On the circulation of hydrogen in the atmosphere and the Earth’s crust ». Geofizicheskiy Zhurnal 43, n^o 5 (24 novembre 2021) : 35–59. http://dx.doi.org/10.24028/gzh.v43i5.244051.

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A review of data on sources and sinks of hydrogen of various origins in the atmosphere and in the near-surface part of the Earth’s crust is given (only some cases we are talking about the crust as a whole). Based on the results of the consideration of this information, it was concluded that the influence of underground non-biogenic («geological») hydrogen on the content and balance of gas in the atmosphere, up to the stratosphere, is insignificant. The complexity of the experimental determination of the flow of geological hydrogen, free of biogenic and anthropogenic interference, the influence of the testable excavation, etc. is obvious. Probable sources of deep hydrogen are considered: the remains of magmatic gases (outside the areas of volcanism), metamorphic reactions, and radiolysis of water. The potential for significant H2 flow is only apparent in areas of currently activated faults. The data on the most powerful suppliers of geological hydrogen — modern active volcanoes and thermal fields are given. The gas circulation scheme of the Avachinsky volcano is built, based on the thermal model. The latter is controlled by data from geothermometers, the results of direct temperature measurements in deep wells, and a velocity model. The possibility of fumaroles carrying unchanged hydrogen from the magma chamber has been shown. The prospects for the formation of hydrogen deposits are estimated as uncertain. Magmatic and metamorphogenic gas in some areas is formed enough to accumulate a significant deposit over several tens of thousands of years. But the possibility of its preservation during this period or longer raises doubts. Hydrocarbon deposits without material input from great depths can lose reserves in much less time. Higher rocks permeability to hydrogen contributes to much greater gas leakage.

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Cimarelli, C., M. A. Alatorre-Ibargüengoitia, U. Kueppers, B. Scheu et D. B. Dingwell. « Experimental generation of volcanic lightning ». Geology 42, n^o 1 (janvier 2014) : 79–82. http://dx.doi.org/10.1130/g34802.1.

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Rutherford, Malcolm J. « Experimental petrology applied to volcanic processes ». Eos, Transactions American Geophysical Union 74, n^o 5 (2 février 1993) : 49–55. http://dx.doi.org/10.1029/93eo00142.

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Longhi, John. « Experimental petrology and petrogenesis of mare volcanics ». Geochimica et Cosmochimica Acta 56, n^o 6 (juin 1992) : 2235–51. http://dx.doi.org/10.1016/0016-7037(92)90186-m.

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Liu, Xiao-Yang, Chang-Ming Wang, Hai-Liang Liu et Di Wu. « An Experimental Investigation of the Mechanical Behavior and Particle Crushing Characteristic of Volcanic Soil ». Materials 15, n^o 15 (6 août 2022) : 5423. http://dx.doi.org/10.3390/ma15155423.

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Volcanic soil is a special soil that is well-known for its distinctive texture, vesicular nature, and particle fragility. The fragility characteristic of volcanic soil is the main factor affecting the foundation stability in road engineering. This study focuses on the mechanical properties and particle crushing characteristics of volcanic soil retrieved from Northeast China. A series of triaxial consolidation and drainage shear tests are performed on volcanic coarse-grained soil (5 mm > d > 0.075 mm) under different initial relative densities and effective confining pressures. Results show the peak friction angle of volcanic soil significantly decreases with the increase of confining pressure. The particle crushing degree of volcanic soil increases with the increase of confining pressure, particle size, and relative density. The relative breakage rate of the same particle size group has a good linear relationship with a fractal dimension. Moreover, for the same particle size, the relationship between plastic work and relative breakage rate can be fitted by a power function, which is not significantly affected by relative density or effective confining pressure. From an engineering view, in addition to increasing the compaction degree of volcanic soil, volcanic soil with fine particles used as a roadbed filler can significantly reduce the deformation of the roadbed and improve the bearing capacity of the foundation.

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Büttner, R., H. Röder et B. Zimanowski. « Electrical effects generated by experimental volcanic explosions ». Applied Physics Letters 70, n^o 14 (7 avril 1997) : 1903–5. http://dx.doi.org/10.1063/1.118726.

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Segura, A., et R. Navarro-González. « Experimental simulation of early martian volcanic lightning ». Advances in Space Research 27, n^o 2 (janvier 2001) : 201–6. http://dx.doi.org/10.1016/s0273-1177(01)00048-5.

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Lavallée, Yan, Thomas M. Mitchell, Michael J. Heap, Jérémie Vasseur, Kai-Uwe Hess, Takehiro Hirose et Donald B. Dingwell. « Experimental generation of volcanic pseudotachylytes : Constraining rheology ». Journal of Structural Geology 38 (mai 2012) : 222–33. http://dx.doi.org/10.1016/j.jsg.2012.02.001.

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Burlini, Luigi, Sergio Vinciguerra, Giulio Di Toro, Giuseppe De Natale, Philip Meredith et Jean-Pierre Burg. « Seismicity preceding volcanic eruptions : New experimental insights ». Geology 35, n^o 2 (2007) : 183. http://dx.doi.org/10.1130/g23195a.1.

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Capponi, Antonio, Steve J. Lane, Jennie S. Gilbert, David G. Macfarlane, Duncan A. Robertson et Mike R. James. « A novel experimental chamber for the characterization of free-falling particles in volcanic plumes ». Review of Scientific Instruments 93, n^o 7 (1 juillet 2022) : 075105. http://dx.doi.org/10.1063/5.0093730.

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Volcanic plumes pose a hazard to health and society and a particular risk for aviation. Hazard mitigation relies on forecasting plume dispersion within the atmosphere over time. The accuracy of forecasts depends on our understanding of particle dispersion and sedimentation processes, as well as on the accuracy of model input parameters, such as the initial particle size distribution and concentrations of volcanic particles (i.e., volcanic ash) in the atmosphere. However, our understating of these processes and the accurate quantification of input parameters remain the main sources of uncertainty in plume dispersion modeling. It is usually impractical to sample volcanic plumes directly, but particle sedimentation can be constrained in the laboratory. Here, we describe the design of a new experimental apparatus for investigating the dynamics of free-falling volcanic particles. The apparatus can produce a sustained column of falling particles with variable particle concentrations appropriate to a volcanic plume. Controllable experimental parameters include particle size distributions, types, and release rates. A laser-illuminated macrophotography system allows imaging of in-flight particles and their interactions. The mass of landing particles is logged to inform deposition rates. Quantitative measurements include particle morphology characterization, settling velocities, flow rates, and estimation of concentrations. Simultaneous observations of particle interaction processes and settling dynamics through direct control over a wide range of parameters will improve our parameterization of volcanic plume dynamics. Although the apparatus has been specifically designed for volcanological investigations, it can also be used to explore the characteristics of free-falling particle columns occurring in both environmental and industrial settings.

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Jianhui, Wang, et Fu Shaojun. « Experimental Study on Cement Admixed with Volcanic Ash ». IOP Conference Series : Materials Science and Engineering 439 (5 novembre 2018) : 042022. http://dx.doi.org/10.1088/1757-899x/439/4/042022.

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Haug, Øystein Thordén, Olivier Galland et Galen R. Gisler. « Experimental modelling of fragmentation applied to volcanic explosions ». Earth and Planetary Science Letters 384 (décembre 2013) : 188–97. http://dx.doi.org/10.1016/j.epsl.2013.10.004.

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Romero, Alfredo, et Rafael Navarro-Gonzalez. « Experimental simulation of archean volcanic lightning : Power measurements ». Origins of Life and Evolution of the Biosphere 26, n^o 3-5 (octobre 1996) : 336–37. http://dx.doi.org/10.1007/bf02459794.

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Liu, Zhidi, et Jingzhou Zhao. « An Experimental Study of Velocity-Saturation Relationships in Volcanic Rocks ». Open Petroleum Engineering Journal 8, n^o 1 (31 mars 2015) : 142–52. http://dx.doi.org/10.2174/1874834101508010142.

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In this paper, experiments are carried out under different pressures and water saturations using core samples of volcanic rocks from the Junggar Basin in China to understand how water saturation affects P- and S-wave velocities. The results show that water saturated rocks exhibit significantly higher P- and S-wave velocities than gas saturated rocks. In addition, the P- and S-wave velocity ratio declines with increasing water saturation. Furthermore, a P- and S-wave velocity ratio vs. resistivity cross plot is created to identify gas reservoirs in the volcanic rocks in the Junggar Basin.

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Soloviev, V., V. Bakhmutov, N. Yakymchuk et I. Korchagin. « Deep structure and new experimental data of the Bransfield Strait volcanoes (West Antarctica) ». Ukrainian Antarctic Journal, n^o 1 (2021) : 3–15. http://dx.doi.org/10.33275/1727-7485.1.2021.661.

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The aim of the study is to determine the existence of a complex magma-gas-fluid system of the West Antarctica northern volcanic branch in the Bransfield Strait. It consists of several different-level deep magma chambers with magmas raised directly from the mantle or the accumulation zone located at a depth of about 25–30 km. Research methods are based on the known idea that the Earth can be considered a spherical capacitor formed by various layers from its core to the surface with different parameters — thickness, permittivity, density, contact potential difference. Our experimental data show that there is a molten zone at 195–225 km where considerable part of volcanic roots is located. Certain structural patterns for land and submarine volcanic structures are revealed, and the first data on the deep migration channels of fluids in the Bransfield Strait are obtained. Volcanic channels are filled with different basic, ultramafic rocks, and sedimentary rocks too. The deep roots of volcanic structures' presence can be associated with the pulsed functioning of a gas-fluid channel with low viscosity. The gas-saturated melts form some zones of intermediate crystallization in the crust due to this channel. These studies showed that multiphase pulsed volcanic activity mainly through the vertical migration channels of deep fluids from the melting zone played a significant role in forming the tectonic diversity and the evolution of the Antarctic continental margin region structures. The results of modified methods of processing and decoding satellite images and photographs allow supplementing the understanding of the West Antarctica structures’ formation. These results of the Bransfield Strait magmatic systems studying indicate the need for further research to understand the mechanism of formation and evolution of structures and deep geospheres in different regions of the Earth.

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Dou, Li Jun, Min Zhang et Ming Yu Xu. « Experimental Research on Compressive Strength of Pumice Concrete and Volcanic Concrete Wall ». Advanced Materials Research 919-921 (avril 2014) : 1801–4. http://dx.doi.org/10.4028/www.scientific.net/amr.919-921.1801.

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Pumice concrete and volcanic concrete used in low-rise rural residential building more and more. In order to better realize the pumice concrete wall and cinder concrete wall compressive strength, respectively to make three slices of pumice concrete wall and three slices of cinder concrete wall, wall compressive experiment was carried out. The experimental results showed that the compressive strength of pumice concrete wall and volcanic concrete wall meet the requirements of the bearing capacity of masonry structure.

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Catalan, Leyre, Miguel Araiz, Patricia Aranguren, German D. Padilla, Pedro A. Hernandez, Nemesio M. Perez, Celestino Garcia de la Noceda, Jose F. Albert et David Astrain. « Prospects of Autonomous Volcanic Monitoring Stations : Experimental Investigation on Thermoelectric Generation from Fumaroles ». Sensors 20, n^o 12 (23 juin 2020) : 3547. http://dx.doi.org/10.3390/s20123547.

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Fumaroles represent evidence of volcanic activity, emitting steam and volcanic gases at temperatures between 70 and 100 ∘ C . Due to the well-known advantages of thermoelectricity, such as reliability, reduced maintenance and scalability, the present paper studies the possibilities of thermoelectric generators, devices based on solid-state physics, to directly convert fumaroles heat into electricity due to the Seebeck effect. For this purpose, a thermoelectric generator composed of two bismuth-telluride thermoelectric modules and heat pipes as heat exchangers was installed, for the first time, at Teide volcano (Canary Islands, Spain), where fumaroles arise in the surface at 82 ∘ C . The installed thermoelectric generator has demonstrated the feasibility of the proposed solution, leading to a compact generator with no moving parts that produces a net generation between 0.32 and 0.33 W per module given a temperature difference between the heat reservoirs encompassed in the 69–86 ∘ C range. These results become interesting due to the possibilities of supplying power to the volcanic monitoring stations that measure the precursors of volcanic eruptions, making them completely autonomous. Nonetheless, in order to achieve this objective, corrosion prevention measures must be taken because the hydrogen sulfide contained in the fumaroles reacts with steam, forming sulfuric acid.

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Pan, Baozhi, Weiyi Zhou, Yuhang Guo, Zhaowei Si et Fawu Lin. « Experimental Study on the Saturation Model of Volcanic Rock Based on Fluid Distribution ». Petrophysics – The SPWLA Journal of Formation Evaluation and Reservoir Description 62, n^o 4 (1 août 2021) : 422–33. http://dx.doi.org/10.30632/pjv62n4-2021a6.

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A saturation evaluation model suitable for Nanpu volcanic rock formation is established based on the experiment of acoustic velocity changing with saturation during the water drainage process of volcanic rock in the Nanpu area. The experimental data show that in the early stage of water drainage, the fluid distribution in the pores of rock samples satisfies the patchy formula. With the decrease of the sample saturation, the fluid distribution in the pores is more similar to the uniform fluid distribution model. In this paper, combined with the Gassmann-Brie and patchy formula, the calculation equation of Gassmann-Brie-Patchy (G-B-P) saturation is established, and the effect of contact softening is considered. The model can be used to calculate water saturation based on acoustic velocity, which provides a new idea for the quantitative evaluation of volcanic oil and gas reservoirs using seismic and acoustic logging data.

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Gagnepain-Beyneix, J., J. C. Lépine, A. Nercessian et A. Hirn. « Experimental study of site effects in the Fort-de-France area (Martinique island) ». Bulletin of the Seismological Society of America 85, n^o 2 (1 avril 1995) : 478–95. http://dx.doi.org/10.1785/bssa0850020478.

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Abstract We used weak-motion recordings of regional events to quantify the site effects in the Fort-de-France (Martinique) area in the frequency band 1 to 25 Hz. The studied area extends over three distinct geological units: the Morne-Pitault volcanic massif (15 to 11 M.A.), the Carbet volcanic massif (4 to 2 M.A.), and the Lamentin alluvial plain (quaternary age). The topography being complex, 31 sites were selected in order to get a representative sampling of the various topographical and geological configurations. The large number of studied sites also allowed us to define a reference site whose selection was not obvious. Large broadband amplifications are observed in the Lamentin plain instead of the expected peak resonances. More surprising, such resonance is observed around 2 to 3 Hz on several sites of the volcanic Vauclain-Pitault chain, though no sedimentary layer is present. On the other hand, in the inner Fort-de-France where significant effects were expected because of the very complex topography, no large amplication is observed except for at one site. Clear three-dimensional (3D) effects are also observed at some stations. Though not very well documented, the low-frequency behavior deduced from teleseismic observations seems rather different, illustrating the difficulty in finding a convenient reference site in such a volcanic area.

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Li, Lailin, Haibo Zhao et Xuehui Han. « Rock Physical Experimental Research in Tanan Volcanic Rock Reservoir ». Journal of Applied Mathematics and Physics 02, n^o 06 (2014) : 284–95. http://dx.doi.org/10.4236/jamp.2014.26034.

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Allen, Carlton C., Richard V. Morris et David S. McKay. « Experimental reduction of lunar mare soil and volcanic glass ». Journal of Geophysical Research : Planets 99, E11 (25 novembre 1994) : 23173–85. http://dx.doi.org/10.1029/94je02321.

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Timmreck, Claudia, Graham W. Mann, Valentina Aquila, Rene Hommel, Lindsay A. Lee, Anja Schmidt, Christoph Brühl et al. « The Interactive Stratospheric Aerosol Model Intercomparison Project (ISA-MIP) : motivation and experimental design ». Geoscientific Model Development 11, n^o 7 (5 juillet 2018) : 2581–608. http://dx.doi.org/10.5194/gmd-11-2581-2018.

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Abstract. The Stratospheric Sulfur and its Role in Climate (SSiRC) Interactive Stratospheric Aerosol Model Intercomparison Project (ISA-MIP) explores uncertainties in the processes that connect volcanic emission of sulfur gas species and the radiative forcing associated with the resulting enhancement of the stratospheric aerosol layer. The central aim of ISA-MIP is to constrain and improve interactive stratospheric aerosol models and reduce uncertainties in the stratospheric aerosol forcing by comparing results of standardized model experiments with a range of observations. In this paper we present four co-ordinated inter-model experiments designed to investigate key processes which influence the formation and temporal development of stratospheric aerosol in different time periods of the observational record. The Background (BG) experiment will focus on microphysics and transport processes under volcanically quiescent conditions, when the stratospheric aerosol is controlled by the transport of aerosols and their precursors from the troposphere to the stratosphere. The Transient Aerosol Record (TAR) experiment will explore the role of small- to moderate-magnitude volcanic eruptions, anthropogenic sulfur emissions, and transport processes over the period 1998–2012 and their role in the warming hiatus. Two further experiments will investigate the stratospheric sulfate aerosol evolution after major volcanic eruptions. The Historical Eruptions SO2 Emission Assessment (HErSEA) experiment will focus on the uncertainty in the initial emission of recent large-magnitude volcanic eruptions, while the Pinatubo Emulation in Multiple models (PoEMS) experiment will provide a comprehensive uncertainty analysis of the radiative forcing from the 1991 Mt Pinatubo eruption.

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Zanchettin, Davide, Myriam Khodri, Claudia Timmreck, Matthew Toohey, Anja Schmidt, Edwin P. Gerber, Gabriele Hegerl et al. « The Model Intercomparison Project on the climatic response to Volcanic forcing (VolMIP) : experimental design and forcing input data for CMIP6 ». Geoscientific Model Development 9, n^o 8 (17 août 2016) : 2701–19. http://dx.doi.org/10.5194/gmd-9-2701-2016.

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Abstract. The enhancement of the stratospheric aerosol layer by volcanic eruptions induces a complex set of responses causing global and regional climate effects on a broad range of timescales. Uncertainties exist regarding the climatic response to strong volcanic forcing identified in coupled climate simulations that contributed to the fifth phase of the Coupled Model Intercomparison Project (CMIP5). In order to better understand the sources of these model diversities, the Model Intercomparison Project on the climatic response to Volcanic forcing (VolMIP) has defined a coordinated set of idealized volcanic perturbation experiments to be carried out in alignment with the CMIP6 protocol. VolMIP provides a common stratospheric aerosol data set for each experiment to minimize differences in the applied volcanic forcing. It defines a set of initial conditions to assess how internal climate variability contributes to determining the response. VolMIP will assess to what extent volcanically forced responses of the coupled ocean–atmosphere system are robustly simulated by state-of-the-art coupled climate models and identify the causes that limit robust simulated behavior, especially differences in the treatment of physical processes. This paper illustrates the design of the idealized volcanic perturbation experiments in the VolMIP protocol and describes the common aerosol forcing input data sets to be used.

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Romero-Mancilla, Pablo Eduardo, José Miguel Montenegro-Cooper, Robert W. King, Pablo Lapeña-Mañero et Carmen García-Casuso. « Experimental Investigation on the Influence of Oven-Drying on the Geotechnical Properties of Volcanic Ash-Derived Residual Soils ». Applied Sciences 11, n^o 24 (9 décembre 2021) : 11708. http://dx.doi.org/10.3390/app112411708.

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For thousands of years, the volcanic activity present along the Andes Mountain range has generated a large amount of pyroclastic material. As a result, around 60 percent of the soils present in Chile have a volcanic origin, of which, we can find soils derived from volcanic ash. These correspond to soils whose origin is the weathering of volcanic ash, which generates minerals such as allophane, imogolite, and halloysite. The presence of these minerals gives these soils unique geotechnical properties, such as high plasticity, low dry unit weight, and a unique internal structure. Subjecting these soils to extreme temperatures like those needed to perform standard laboratory tests produces changes in their structures, and thus in their geotechnical behavior. These changes are important to be aware of with respect to slope stability problems, embankment conformation, surface foundations, etc. In the present study, a type of soil found in Chile originating from the weathering of volcanic ash and locally named Trumao was studied. Due to its age and formation processes, the main minerals found in the soil are allophane and imogolite, and hence it belongs to the allophanic soil type. The material was studied in its natural state (undisturbed) and, after being oven-dried using common geotechnical tests, the behaviors of both samples were compared. The study shows that some properties are affected significantly by the oven-drying process, and thus it is not recommended to expose the material to high temperatures during geotechnical laboratory testing to avoid misleading results.

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Hakim, Wahyu Luqmanul, Suci Ramayanti, Sungjae Park, Bokyun Ko, Dae-Kyo Cheong et Chang-Wook Lee. « Estimating the Pre-Historical Volcanic Eruption in the Hantangang River Volcanic Field : Experimental and Simulation Study ». Remote Sensing 14, n^o 4 (13 février 2022) : 894. http://dx.doi.org/10.3390/rs14040894.

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The volcanic landforms associated with fluvial topography in the Hantangang River Volcanic Field (HRVF) have geoheritage value. The Hantangang basalt geological landform stretches along 110 km of the paleoriver channel of the Hantangang River. Since the eruption that formed this basalt occurred from 0.15 to 0.51 Ma, estimating the eruption in the HRVF that originated from two source vents in North Korea (Orisan Mountain and the 680 m peak) is challenging due to the limited recorded data for this eruption. In this study, we estimated this prehistorical eruption using 3D printing of a terrain model and Q-LavHA simulation. The results from the experiment were further analyzed using findings from an artificial neural network (ANN) and support vector machine (SVM) to classify the experimental lava area. The SVM classification results showed higher accuracy and efficiency in the computational process than the ANN algorithm. Results from the single eruptive vent scenario showed that the experiment had a higher accuracy than the Q-LavHA simulation. Further analysis of multiple vent scenarios in the Q-LavHA simulation has improved the accuracy compared with the single eruptive vent scenarios.

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Den Tex, Emile. « Clinchers of the Basalt Controversy : Empirical and Experimental Evidence ». Earth Sciences History 15, n^o 1 (1 janvier 1996) : 37–48. http://dx.doi.org/10.17704/eshi.15.1.alq023j2l872p107.

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The 18th century basalt controversy had two aspects: its sedimentary versus volcanic nature, and its superficially combustive versus deeply derived origin. The neptunistic answer to the first question prevailed around the middle of the century owing to the general validity of the Wernerian lithostratigraphy at that time. Clinching evidence for the volcanic nature of basalt came forward in the final quarter of the century, essentially from countries with active or recently extinguished volcanoes-like Italy and France-while fusion experiments and chemical bulk analyses proved the similarity of basalt and basic lavas. Throughout the 18th century, the origin of basalt was held to be due to the superficial combustion of coal, bitumen, oil, sulphur, etc., even by confirmed Vulcanists. At the very end of the century Werner's lithostratigraphic system became liable to serious doubts. Basaltic volcanoes were found to have derived their material from underneath Werner's oldest formation: the granitoid ‘Urgebirge’, where neither combustible matter nor air could have been available. Also the melting temperatures of lava and basalt were experimentally shown to be higher than the temperatures of burning combustible materials. Thus a firm link was established between the hypotheses of Vulcanism and Huttonian Plutonism.

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Orlando, Andrea, Sandro Conticelli, Pietro Armienti et Daniele Borrini. « Experimental study on a basanite from the McMurdo Volcanic Group, Antarctica : inference on its mantle source ». Antarctic Science 12, n^o 1 (mars 2000) : 105–16. http://dx.doi.org/10.1017/s0954102000000134.

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Experiments to reconstruct the liquidus curve and establish the phase relationships of a basanite (Mg# = 72) from the McMurdo Volcanic Group, (thought to represent a nearly primary magma) used 1.0– 3.0 GPa and 1175–1550°C. The results suggest that this basanite could be generated by partial melting either of a spinel Iherzolite (at P = 1.5–2.0 GPa and T = 1390–1490°C) or of a garnet pyroxenite (at P > 3.0 GPa and T > 1550°C) source. Several lines of petrological and geochemical evidence support the latter hypothesis. Moreover, experimental results indicate the presence of mica in the source if it is assumed that the magma lost some water during its ascent to the surface. This is supported by the presence of mica and amphibole-bearing mantle xenoliths hosted in the most primitive volcanic rocks of the McMurdo Volcanic Group. These results and observations suggest that the source of magmas underwent metasomatism prior to partial melting.

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