Journal of Volcanology and Geothermal Research最新文献

{"title":"Recycled materials and secondary processes controlled the chemical and isotopic compositions of bubbling gases discharged from two adjacent geothermal springs in the Northern Luzon Arc","authors":"Jia-Yi Wu ,&nbsp;Xue-Gang Chen ,&nbsp;Mark Schmidt ,&nbsp;Xiaohu Li ,&nbsp;Chen-Tung Arthur Chen ,&nbsp;Ying Ye","doi":"10.1016/j.jvolgeores.2024.108108","DOIUrl":"10.1016/j.jvolgeores.2024.108108","url":null,"abstract":"<div><p>Gas emissions from hydrothermal systems can serve as indicators of subsurface activity. In addition to gas sources, hydrothermal gas geochemistry is strongly influenced by secondary processes that occur during/after hydrothermal circulation. Here, we observed statistically significant differences in the geochemical characteristics (except for helium isotopes) of bubbling gases discharged from two adjacent vents in the Northern Luzon Arc. Helium (³He/⁴He = 4.25–7.09 <em>R</em>_<em>a</em>) in both vents was controlled by mixing between mantle and crustal components, where about 74% of helium was contributed by the mantle. Differences in N₂/Ar ratios (∼ 300–330) of the two neighboring springs are attributed to subducted materials and seawater mixing (contributing ∼2.5% N₂ and Ar), rather than phase separation in the reaction zone. Specifically, Ar was mainly supplied by atmospheric components that dissolved in the percolated seawater with only 8%–9% contributed by the excess radiogenic ⁴⁰Ar. Excess N₂ relative to Ar was mainly supplied by the decomposition of subducted materials (83%–92%) of the South China Sea plate beneath the Philippine Sea Plate. The Lutao gases showed low CO₂ concentrations (0.07–22.2 mmol/mol), despite the high ³He/⁴He ratios indicating a significant contribution of magmatic components. Magmatic CO₂ may have been largely consumed by the high Ca Lutao vent fluids via carbonate precipitation in the reaction zone. Alternatively, stable carbon isotope compositions (δ¹³C) indicate that Lutao CO₂ may be supplied by microbial oxidation of alkanes (e.g., CH₄ with concentrations of 14.6–173 mmol/mol in the samples), with fractionation factor ΔCO₂–CH₄ ranging from −15‰ to −25‰ and conversion rates of &lt;10%. Up to 65% of the CO₂ in the 2016 samples experienced secondary calcite precipitation in the discharge zone. Our results indicate that recycled subducted materials could potentially affect the geochemical characteristics of gases discharged from arc-volcanic systems. In addition, the influence of secondary processes needs to be considered before tracing the sources of hydrothermal fluids and/or gases, especially in shallow-water hydrothermal systems.</p></div>","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"451 ","pages":"Article 108108"},"PeriodicalIF":2.9,"publicationDate":"2024-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141050904","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Internal structure of the volcanic island of Surtsey and surroundings: Constraints from a dense aeromagnetic survey","authors":"Sara Sayyadi ,&nbsp;Magnús T. Gudmundsson ,&nbsp;James D.L. White ,&nbsp;Thorsteinn Jónsson ,&nbsp;Maxwell C. Brown ,&nbsp;Marie D. Jackson","doi":"10.1016/j.jvolgeores.2024.108096","DOIUrl":"10.1016/j.jvolgeores.2024.108096","url":null,"abstract":"<div><p>Surtsey, a young basaltic island off the south coast of Iceland, was built by volcanic activity in 1963–1967 from a pre-eruption oceanic seafloor depth of 130 m. An aeromagnetic survey was carried out in October 2021 over a 60 km² area covering Surtsey and its surroundings. It aimed to explore the internal structure and the possible existence of basaltic intrusions associated with the five vents active at different times over the 3.5 years of eruptive activity. The survey line spacing was 200 m and the flying altitude was generally 90 m a.s.l. The strongest anomalies (amplitude ∼700 nT) are caused by the 30–100 m thick subaerially erupted lava field on the southern part of Surtsey, formed in two episodes of effusive activity:1964–1965 and 1966–1967. 2D spectral analysis and Euler deconvolution indicate that the causative bodies of anomalies outside the island of Surtsey are located within the uppermost 300 m of the seafloor and their horizontal dimensions are similar to or smaller than their depth. 3D forward modeling of the island and its surroundings, constrained by observations during the formation of the island and drill cores extracted in 1979 and 2017, is consistent with an absence, at all vents, of pillow lava and therefore effusive activity in their opening phases. However, the data support the existence of a 10–20 m thick pillow lava field on the seafloor, 2.5–3 km² in area, extending about ∼1 km to the south of Surtsey. The field is considered to have been fed by magma reaching the seafloor via channelized intrusive flow through the foreset breccia constituting the submarine part of an emerging lava delta during the early stage of effusive eruption in May–July 1964. The general scarcity of significant magnetic bodies within the edifices is consistent with magma fragmentation dominating the submarine eruptions from the onset of activity. A small magnetic anomaly is observed over the submarine edifice of Surtla, built during short-lived activity over ∼10 days in 1963–1964. This anomaly is consistent with observed subaqueous weak or moderate explosive activity that may have allowed a dyke to be preserved within the submarine tephra mound. More violent Surtseyan activity was observed at other vents, however, and may have destroyed any initial dykes that, if preserved, might have been resolved magnetically. Indications of magnetized volcanic rocks of unknown age predating the Surtsey eruption are found beneath the flank of the ephemeral island of Jólnir, the southernmost of the Surtsey vents.</p></div>","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"451 ","pages":"Article 108096"},"PeriodicalIF":2.9,"publicationDate":"2024-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S037702732400088X/pdfft?md5=b6331033c0a83f7b997395f5cb204393&pid=1-s2.0-S037702732400088X-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141025388","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reconstructing episodic and multi-vent, rhyolitic eruptions: The ∼ 1314 CE Kaharoa eruption of the Tarawera Dome Complex, Okataina Caldera (New Zealand)","authors":"Andrea Todde,&nbsp;Jonathan N. Procter,&nbsp;Gabor Kereszturi","doi":"10.1016/j.jvolgeores.2024.108107","DOIUrl":"10.1016/j.jvolgeores.2024.108107","url":null,"abstract":"<div><p>Detailed stratigraphic reconstructions and quantitative deposit characterisations of moderate to large-scale rhyolitic eruptions are limited. This hinders our ability to model the multiple eruptive phenomena and hazards associated with rhyolitic volcanism. To gain new perspectives on the patterns and behaviours of rhyolitic eruptions, we present a study on the explosive phases of the 1314 ± 12 CE Kaharoa eruption of Tarawera, New Zealand. The eruption occurred from multiple aligned vents within the Okataina Caldera and is the youngest rhyolitic eruption of the frequently active Taupō Volcanic Zone. We systematically quantify the deposit characteristics of the Kaharoa pyroclastic succession to provide new insights into the type of eruption sequence and eruptive style changes. Based on field evidence, stratigraphic correlations, grain size and componentry analyses, we subdivide the Kaharoa deposit into 24 units and identify 7 main deposit types, which are linked to different eruptive and depositional processes. The explosive activity was discontinuous, characterised by repeated discrete episodes of sustained magma discharge separated by short time breaks. The activity consisted mainly of repeated subplinian-type columns that gave way to fallout deposition and emplacement of numerous lapilli beds. This activity transitioned to a pyroclastic density current (PDC) dominated phase in response to lateral vent migration. Ash emission activity occurred within and towards the end of the explosive sequence, indicating declines in the eruptive intensity. Six main intra-eruption phases (A to F) of dominant eruptive styles are established to describe the temporal evolution of the eruption. Phases A, B and D are associated with the repeated subplinian-type activity. Phase C comprises the major PDC activity, while the final two Phases E and F are associated with ash emission during initiation of lava dome extrusion and to the final dome-building sequence. This study highlights the complex nature of episodic, multi-phase, and multi-vent, explosive to dome-forming rhyolitic eruptions, depicting a scenario of great relevance for future volcanic hazard studies at active rhyolitic volcanoes worldwide.</p></div>","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"451 ","pages":"Article 108107"},"PeriodicalIF":2.9,"publicationDate":"2024-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141053216","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The impacts of lulls and peaks in eruption rate on lava flow propagation","authors":"S.I. Peters ,&nbsp;A.B. Clarke ,&nbsp;E.L. Rader","doi":"10.1016/j.jvolgeores.2024.108099","DOIUrl":"10.1016/j.jvolgeores.2024.108099","url":null,"abstract":"&lt;div&gt;&lt;p&gt;Variable effusion rates have been observed during the eruption and emplacement of lava flows which can complicate lava flow predictability. Conventional wisdom suggests that eruption rates decrease exponentially with time, however, this broad trend may also be subject to short-timescale fluctuations. Flow obstructions, changes in source diameter, channel or pond overflow, and changes within the magma reservoir to name a few factors can increase or decrease local flow rates repeatedly during an active eruption and impact the behavior of the flow. Analog experiments are a useful tool for investigating the role of changing effusion rates on flow propagation because they allow reasonably precise control of conditions and detailed documentation of resulting flows. In this work, we address the effects of decreasing and increasing extrusion rates (Q) on flow propagation and four emplacement modes common to lava flows: &lt;em&gt;resurfacing, marginal breakouts, inflation, and lava tubes&lt;/em&gt;. We conducted 30 experiments by injecting dyed PEG wax into a chilled bath (∼ 0 °C) on a flat slope. We divided the experiments into two pulsatory extrusion rate patterns, or conditions: stepwise decrease followed by increase in extrusion rate (lull) and stepwise increase then decrease in extrusion rate (peak). We tested a range of flow conditions spanning from flows for which strong crust was favored (low wax temperature; low extrusion rates) and those for which weak crust was favored (high wax temperature; high extrusion rates). We found that a lull in extrusion rates when a strong crust was present promoted flow expansion and thickening via limited resurfacing, localized marginal breakouts, inflation, possible tube formation, with lower rates of flow expansion after the lull. In contrast, a lull and weak crust promoted flow expansion via widespread marginal breakouts, with flow advance rebounding after the lull, and inhibited flow thickening via inflation. A peak in extrusion rates with a strong crust favored flow expansion via widespread marginal breakouts, with flow-advance deceleration after the peak, and possible thickening via inflation. Conversely, a peak in extrusion rate with weak crust promoted flow expansion via widespread marginal breakouts, with flow-advance deceleration after the peak, and inhibited flow thickening via resurfacing and inflation. Our results have implications for pahoehoe flow emplacement and have been used to assess the most appropriate parameters to be used in a probabilistic flow propagation model, MrLavaLoba.&lt;/p&gt;&lt;/div&gt;&lt;div&gt;&lt;h3&gt;Plain Language Summary&lt;/h3&gt;&lt;p&gt;Variable effusion rates have been observed during the eruption of lava flows which can complicate lava flow forecasts. In general, lava flow effusion rates decrease with time exponentially although there may be fluctuations in flow rate on short timescales. Flow rates can wax or wane for a variety of reasons, such as flow obstructions, changes in the shape of the erupting sourc","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"451 ","pages":"Article 108099"},"PeriodicalIF":2.9,"publicationDate":"2024-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S037702732400091X/pdfft?md5=6ae5beb33f650e49c12869c027b0836e&pid=1-s2.0-S037702732400091X-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141029077","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A lower bound on the rheological evolution of magma in the 2021 Fagradalsfjall Fires","authors":"Arianna Soldati ,&nbsp;Donald B. Dingwell ,&nbsp;Thorvaldur Thordarson ,&nbsp;Ármann Höskuldsson ,&nbsp;Ingibjörg Jónsdóttir ,&nbsp;William M. Moreland ,&nbsp;Jóna S. Pálmadóttir ,&nbsp;Catherine R. Gallagher ,&nbsp;Helga K. Torfadóttir ,&nbsp;Jacqueline Grech Licari ,&nbsp;Iðunn Kara Valdimarsdóttir ,&nbsp;Lilja B. Pétursdóttir ,&nbsp;Robert A. Askew","doi":"10.1016/j.jvolgeores.2024.108098","DOIUrl":"https://doi.org/10.1016/j.jvolgeores.2024.108098","url":null,"abstract":"<div><p>As magma temperature and composition drift and change, respectively, throughout an eruption, so does its rheology. These changes may span orders of magnitude in magma viscosity and result in orders of magnitude flow velocity changes, as well as transitions in eruptive style. In this study, we present a systematic high precision quantification of the rheological variations that occurred during the 2021 Fagradalsfjall Fires. In the field, we collected a suite of 22 representative samples emplaced between day 2 and 183 of the 2021 eruption. In the laboratory, we measured the melt viscosity of each sample in a concentric cylinder viscometer. Temperatures were initially raised to 1392 °C, and then lowered stepwise to eruptive temperatures as determined through <em>syn</em>-eruptive radiometric measurements. The resulting dataset is analyzed as a time series. An overall trend of viscosity decrease emerges. As the eruption progressed, melt viscosity decreased by 25%, from 40 Pa s to 30 Pa s at a constant temperature of 1200 °C. However, this trend is not monotonous. At least 3 positive spikes in viscosity can be identified, at day 80, 120, and 138 of the eruption. This trend tracks with geochemical variations.</p></div>","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"451 ","pages":"Article 108098"},"PeriodicalIF":2.9,"publicationDate":"2024-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140947471","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Time scales of olivine storage and transport as revealed by diffusion chronometry at Waitomokia Volcanic Complex, Auckland Volcanic Field, New Zealand","authors":"Rosa Didonna ,&nbsp;Heather Handley ,&nbsp;Helena Albert ,&nbsp;Fidel Costa","doi":"10.1016/j.jvolgeores.2024.108094","DOIUrl":"10.1016/j.jvolgeores.2024.108094","url":null,"abstract":"<div><p>Detailed knowledge of the pre-eruptive time scales associated with magma storage and transport is vital to improve volcanic hazard forecasting in active volcanic regions. However, quantification of the timescales of volcanic processes at mafic volcanic centres in continental intraplate settings is challenging, despite them being a source of significant hazards for human populations and infrastructure due to their limited predictability in space and time. We conducted a detailed petrological study to investigate the time scales of olivine storage and transfer throughout the eruption sequence of Waitomokia Volcanic Complex, a tuff ring and scoria cone complex in the Auckland Volcanic Field. Olivine crystal textures and compositions were determined from stratigraphically-constrained samples of the volcanic complex, from the initial phreatomagmatic phase to the final magmatic phase. Olivine crystals are typically &lt;300 μm in length and characterised by skeletal morphologies, displaying chemical zoning in forsterite (Fo = 100*Mg/[Mg + Fe]; mol%), CaO, MnO and NiO wt% contents. We classified olivine into three major groups based on their Fo core compositions: (1) normally zoned crystals with high Fo content (Fo &gt; 85), (2) crystals with intermediate Fo contents (84–81), and (3) reversely zoned crystals with lower Fo core content (&lt;80). Olivine chemical zoning (diffusion) profiles were modelled in the context of a specific magmatic environment linked with changes in thermodynamic variables during storage (temperature, pressure, and oxygen fugacity). We propose that the normally zoned olivine crystals grew in one magmatic environment (ME1), which subsequently intruded into a more evolved (lower MgO) environment (ME2), where they interacted and were stored for up to 135 days before their eruption. During magma ascent to the surface, a second magma mixing event occurred between ME2 and magma within a third magmatic environment (ME3), forming reversely-zoned olivine crystals yielding notably shorter ascent times of approximately a few days. The rocks from the opening phreatomagmatic phase of the eruption show a larger range in olivine group types compared to the final magmatic phase, where those from the deeper ME1 are more abundant. The short time scales of magma transport obtained in our study, on the order of days to months, should be informative of the warning times that may be encountered between the onset of volcanic unrest and an eruption in the Auckland Volcanic Field.</p></div>","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"451 ","pages":"Article 108094"},"PeriodicalIF":2.9,"publicationDate":"2024-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0377027324000866/pdfft?md5=3a5095b94a81ab9cc9a12af244064f55&pid=1-s2.0-S0377027324000866-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141033308","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The spatial distribution and evolution of volcanic vents in monogenetic fields in active extensional tectonic setting: Examples from the northern Main Ethiopian Rift (Ethiopia)","authors":"Francesco Mazzarini,&nbsp;Ilaria Isola","doi":"10.1016/j.jvolgeores.2024.108093","DOIUrl":"https://doi.org/10.1016/j.jvolgeores.2024.108093","url":null,"abstract":"<div><p>Monogenetic volcanic fields are present in different geo-tectonic settings (subduction, divergence and intraplate settings) consisting of tens to hundreds of volcanic constructs (cones, maars, fissures, small shields) that are the physical expression of distributed volcanism.</p><p>Notably, the spatial distribution of the volcanic constructs in volcanic fields often shows a spatial clustering that is thought to be linked to shallow (i.e., crustal strain, structural inheritance) and deep processes (i.e., magma input, composition and rheology). Noteworthy, the spatial distribution of vents (cones, maars, fissures, small shields) is the final frame of the history of the volcanic field and does not provide information about its time-evolution.</p><p>Consequently, when a vent spatial clustering is assessed for a particular volcanic field two questions remain unanswered: i) have the vents always been clustered during the life of the volcanic field? ii) If not, when did the clustering of vents begin? To answer these questions, the spatial distributions of vents along with their morphologic classification have been applied to volcanic fields located in an active tectonic and volcanic area. The northern Main Ethiopian Rift, being its geo-tectonic setting and its geologic evolution well known, is the locale where the time evolution of vent spatial clustering can be investigated. Spatial distribution and morphometric analysis of vents have been applied to three well known monogenetic volcanic fields (Debre Zeyt, Wonji and Kone) in the northern Main Ethiopian Rift. Vent clustering initiated when about 60% of the vents formed within each of the above mentioned fields. The Kone volcanic field show vent clustering since the beginning suggesting that, within a specific tectonic setting, vent clustering is favoured by crustal strain partitioning and associated volcanic activity.</p></div>","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"451 ","pages":"Article 108093"},"PeriodicalIF":2.9,"publicationDate":"2024-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0377027324000854/pdfft?md5=e8724612c2f9d248c841945b8d01a4fd&pid=1-s2.0-S0377027324000854-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140950943","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Near-real-time multiparametric seismic and visual monitoring of explosive activity at Sabancaya volcano, Peru","authors":"Riky Centeno ,&nbsp;Valeria Gómez-Salcedo ,&nbsp;Ivonne Lazarte ,&nbsp;Javier Vilca-Nina ,&nbsp;Soledad Osores ,&nbsp;Efraín Mayhua-Lopez","doi":"10.1016/j.jvolgeores.2024.108097","DOIUrl":"10.1016/j.jvolgeores.2024.108097","url":null,"abstract":"<div><p>This study presents the development of a multiparametric system that utilizes artificial intelligence techniques to identify and analyze volcanic explosions in near real-time. The study analyzed 1343 explosions recorded between 2019 and 2021, along with seismic, meteorological, and visible image data from the Sabancaya volcano. Deep learning algorithms like the U-Net convolutional neural network were used to segment and measure volcanic plumes in images, while boosting-based machine learning ensembles were used to classify seismic events related to ash plumes. The findings demonstrate that these approaches effectively handle large amounts of data generated during seismic and eruptive crises. The U-Net network achieved precise segmentation of volcanic plumes with over 98% accuracy and the ability to generalize to new data. The CatBoost classifier achieved an average accuracy of 94.5% in classifying seismic events. These approaches enable the real-time estimation of eruptive parameters without human intervention, contributing to the development of early warning systems for volcanic hazards. In conclusion, this study highlights the feasibility of using seismic signals and images to detect and characterize volcanic explosions in near real-time, making a significant contribution to the field of volcanic monitoring.</p></div>","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"451 ","pages":"Article 108097"},"PeriodicalIF":2.9,"publicationDate":"2024-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141032540","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Estimating emission flux of H2S from fumarolic fields using vertical sensor array system","authors":"Yutaka Miyagi ,&nbsp;Urumu Tsunogai ,&nbsp;Kohei Watanabe ,&nbsp;Masanori Ito ,&nbsp;Fumiko Nakagawa ,&nbsp;Ryunosuke Kazahaya","doi":"10.1016/j.jvolgeores.2024.108090","DOIUrl":"https://doi.org/10.1016/j.jvolgeores.2024.108090","url":null,"abstract":"&lt;div&gt;&lt;p&gt;The emission flux of volatiles from each fumarolic field in volcanic and geothermal areas can be used to evaluate the current state of magmatic activity and predict its future trends. The emission flux of &lt;span&gt;&lt;math&gt;&lt;mi&gt;S&lt;/mi&gt;&lt;msub&gt;&lt;mi&gt;O&lt;/mi&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt; has been quantified in many fumarolic fields using remote sensing techniques, such as differential optical absorption spectroscopy (DOAS). However, most of these remote sensing techniques are inapplicable to fumarolic fields emitting volatiles depleted in &lt;span&gt;&lt;math&gt;&lt;mi&gt;S&lt;/mi&gt;&lt;msub&gt;&lt;mi&gt;O&lt;/mi&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt; to which most of the geothermal fields are classified. In this study, we developed a vertical sensor array system to quantify the emission flux of &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/msub&gt;&lt;mi&gt;S&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; from each fumarolic field by integrating the cross-sectional distributions of &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/msub&gt;&lt;mi&gt;S&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; concentrations in the volcanic plume using the vertical sensor array system. In Iwo-yama of the Kirishima volcanic complex, the cross-sectional distribution of &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/msub&gt;&lt;mi&gt;S&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; concentrations was determined using the walking traverse method by moving the vertical sensor array system in the plume perpendicular to the direction of plume transport. The emission flux of &lt;span&gt;&lt;math&gt;&lt;mi&gt;S&lt;/mi&gt;&lt;msub&gt;&lt;mi&gt;O&lt;/mi&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt; (2.2 ± 0.4 ton &lt;span&gt;&lt;math&gt;&lt;mi&gt;S&lt;/mi&gt;&lt;msub&gt;&lt;mi&gt;O&lt;/mi&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;/day) was estimated from that of &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/msub&gt;&lt;mi&gt;S&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; using the walking traverse method (2.6 ± 0.5 ton &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/msub&gt;&lt;mi&gt;S&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt;/day) and the molar ratio of the plume (&lt;span&gt;&lt;math&gt;&lt;mi&gt;S&lt;/mi&gt;&lt;msub&gt;&lt;mi&gt;O&lt;/mi&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;/&lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/msub&gt;&lt;mi&gt;S&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;45&lt;/mn&gt;&lt;/math&gt;&lt;/span&gt;) corresponds well with that estimated optically by JMA. We concluded that the emission flux quantified using the vertical sensor array system was reliable. In the Oyunuma pond in the Kuttara volcano, the emission flux of &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/msub&gt;&lt;mi&gt;S&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; was quantified as 2.0 ton &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/msub&gt;&lt;mi&gt;S&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt;/day through the fixed point method, wherein the vertical sensor array system was fixed in one point, whereas the cross sectional distribution of &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/msub&gt;&lt;mi&gt;S&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; in the plume was estimated using the natural variation in wind direction. The topography is often irregular and wind direction is variable in most fumarolic fields; thus, in general, the fixed point method should be more suitable to determine the emission flux of &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/msub&gt;&lt;mi&gt;S&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; from fumarolic fields, wherein &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/m","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"450 ","pages":"Article 108090"},"PeriodicalIF":2.9,"publicationDate":"2024-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0377027324000829/pdfft?md5=912fda4ba00404380669d349488a7cd2&pid=1-s2.0-S0377027324000829-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140843415","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Nieve volcanic cluster: A Pliocene - Pleistocene lava dome cluster in the Michoacán-Guanajuato volcanic field (México)","authors":"Denis-Ramón Avellán ,&nbsp;Silvestre Cardona-Melchor ,&nbsp;Martha Gabriela Gómez-Vasconcelos ,&nbsp;José Luis Macías ,&nbsp;Paul William Layer ,&nbsp;Giovanni Sosa-Ceballos ,&nbsp;María-Camila Ruíz ,&nbsp;Jeff Benowitz ,&nbsp;Guillermo Cisneros-Máximo ,&nbsp;Hugo Murcia ,&nbsp;Mathieu Perton ,&nbsp;Gabriela Reyes-Agustín ,&nbsp;Felipe García-Tenorio","doi":"10.1016/j.jvolgeores.2024.108091","DOIUrl":"https://doi.org/10.1016/j.jvolgeores.2024.108091","url":null,"abstract":"<div><p>The Nieve monogenetic volcanic cluster is located in the central–eastern region of the Michoacán–Guanajuato volcanic field, along the Huiramba fault zone, a relay ramp in the Morelia–Acambay fault system produced by oblique north-northwest transtension. This volcanic cluster includes at least 17 middle Pliocene to late Pleistocene lava domes, two small shield volcanoes, and two scoria cones. Between 4 and 3.8 Ma, two effusive eruptions built two small shield volcanoes overlying one another, with a magma volume of 3.93 km³. Between 2.9 Ma and 21.4 ka, 17 lava domes and two scoria cones were emplaced on the flanks of these volcanoes. The entire cluster resulted in a total erupted volume of 17 km³, covering an area of <!--> <!-->326 km² and reaching a thickness of emplaced volcanic material of 1200 m, resulting in a magma eruption rate equivalent to 0.004 km³/ka. All the rocks associated with this cluster are within a relatively restricted range in composition, between 53.9 and 64.2 wt% SiO₂, from andesite enriched in silica to basaltic andesite. The presence of intrusive-rock xenoliths and xenocrysts with dissolution textures reveals that assimilation processes modified the magmas. Based on the regional geological record, we suggest that the establishment of the Nieve volcanic cluster has been controlled by tectonic structures and the basement of the region, which has allowed the chemical evolution of these magma batches that probably had sources in at least two deep reservoirs as reflected by the Nb/Th versus Ta/U ratio.</p></div>","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"450 ","pages":"Article 108091"},"PeriodicalIF":2.9,"publicationDate":"2024-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140880175","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}