Pub Date : 2025-12-01Epub Date: 2025-09-21DOI: 10.1016/j.jvolgeores.2025.108453
Jennifer L. Lewicki , Sara Peek , Laura E. Clor , Andrew G. Hunt
The Sulphur Bank Mercury Mine (SBMM) hydrothermal system offers insights into active degassing processes in the Clear Lake volcanic field (CLVF), a high-threat region based on its record of Holocene eruptions and proximity to populated areas. Here we present chemical and isotopic analyses of gas samples collected between 2015 and 2023, along with the first comprehensive CO2 flux survey of the SBMM area conducted in 2023. Sampled gases are CO2- and CH4-rich (≥84 and 6 mol% in dry gas, respectively) with high mantle-derived helium contributions (3He/4He = 6.54–7.86 RC/RA). Carbon isotopic compositions of CO2 (δ13C = −10.0 to −9.5 ‰) and CH4 (δ13C = −35.8 ‰) indicate mixed sources, with significant contributions from metamorphism of organic-rich Franciscan Complex rocks hosting the hydrothermal system. Modeling of gas compositions shows that scrubbing by interaction with air-saturated groundwater strongly influences observed compositional variability. From our CO₂ flux measurements, we estimate the deeply derived CO2 emission rate from the SBMM hydrothermal area (0.2 km2) at 240 t d−1, comparable to many quiescently degassing volcanoes worldwide. We also provide a first-order estimate of CH4 emissions at approximately 0.5 t d−1. Our findings establish crucial baseline data for future volcanic monitoring efforts, enhancing detection capabilities for potential changes in this active hydrothermal system. This work contributes to the broader understanding of volatile contributions from volcanic and metamorphic sources to the global carbon budget, while highlighting the strong influence of bedrock geology on gas compositions in the CLVF.
硫岸汞矿（SBMM）热液系统为clearlake火山场（CLVF）的主动脱气过程提供了见解，clearlake火山场（CLVF）是一个基于全新世火山喷发记录和靠近人口稠密地区的高威胁地区。在这里，我们介绍了2015年至2023年收集的气体样本的化学和同位素分析，以及2023年对SBMM地区进行的第一次全面的二氧化碳通量调查。样品气体富含CO2和ch4（干气≥84 mol%和6 mol%），幔源氦贡献高（3He/4He = 6.54 ~ 7.86 RC/RA）。CO2 （δ13C = - 10.0 ~ - 9.5‰）和CH4 （δ13C = - 35.8‰）的碳同位素组成表明烃源混合，其中富有机质方济各杂岩的变质作用是热液体系的主要来源。气体组成的模拟表明，与空气饱和地下水相互作用的冲刷作用强烈影响观测到的组成变率。根据我们的CO₂通量测量，我们估计SBMM热液区（0.2 km2）的深度衍生CO2排放率为240 t d - 1，与世界上许多静态脱气火山相当。我们还提供了约0.5 t d−1时CH4排放的一阶估计。我们的发现为未来的火山监测工作建立了关键的基线数据，增强了对这一活跃热液系统潜在变化的探测能力。这项工作有助于更广泛地了解火山和变质源对全球碳收支的挥发性贡献，同时突出了基岩地质对CLVF气体组成的强烈影响。
{"title":"Gas emissions from the Sulphur Bank Mercury Mine hydrothermal system, Clear Lake volcanic field, California","authors":"Jennifer L. Lewicki , Sara Peek , Laura E. Clor , Andrew G. Hunt","doi":"10.1016/j.jvolgeores.2025.108453","DOIUrl":"10.1016/j.jvolgeores.2025.108453","url":null,"abstract":"<div><div>The Sulphur Bank Mercury Mine (SBMM) hydrothermal system offers insights into active degassing processes in the Clear Lake volcanic field (CLVF), a high-threat region based on its record of Holocene eruptions and proximity to populated areas. Here we present chemical and isotopic analyses of gas samples collected between 2015 and 2023, along with the first comprehensive CO<sub>2</sub> flux survey of the SBMM area conducted in 2023. Sampled gases are CO<sub>2</sub>- and CH<sub>4</sub>-rich (≥84 and 6 mol% in dry gas, respectively) with high mantle-derived helium contributions (<sup>3</sup>He/<sup>4</sup>He = 6.54–7.86 R<sub>C</sub>/R<sub>A</sub>). Carbon isotopic compositions of CO<sub>2</sub> (δ<sup>13</sup>C = −10.0 to −9.5 ‰) and CH<sub>4</sub> (δ<sup>13</sup>C = −35.8 ‰) indicate mixed sources, with significant contributions from metamorphism of organic-rich Franciscan Complex rocks hosting the hydrothermal system. Modeling of gas compositions shows that scrubbing by interaction with air-saturated groundwater strongly influences observed compositional variability. From our CO₂ flux measurements, we estimate the deeply derived CO<sub>2</sub> emission rate from the SBMM hydrothermal area (0.2 km<sup>2</sup>) at 240 t d<sup>−1</sup>, comparable to many quiescently degassing volcanoes worldwide. We also provide a first-order estimate of CH<sub>4</sub> emissions at approximately 0.5 t d<sup>−1</sup>. Our findings establish crucial baseline data for future volcanic monitoring efforts, enhancing detection capabilities for potential changes in this active hydrothermal system. This work contributes to the broader understanding of volatile contributions from volcanic and metamorphic sources to the global carbon budget, while highlighting the strong influence of bedrock geology on gas compositions in the CLVF.</div></div>","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"468 ","pages":"Article 108453"},"PeriodicalIF":2.3,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145159449","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}
Pub Date : 2025-12-01Epub Date: 2025-10-06DOI: 10.1016/j.jvolgeores.2025.108463
Chiedozie C. Ogbuagu , Kuang C. Lin , Thomas J. Jones , Silvio De Angelis
Explosive volcanic eruptions pose a threat to nearby populations and infrastructure. The erupted pyroclasts (i.e., variably molten droplets) can ballistically travel large distances from the vent, cause range of hazards, and produce a range of deposit types depending on the temperature at which they land. To mitigate these hazards and to perform enhanced quantitative textural analyses of the erupted pyroclasts, there is a need to improve our understanding of the transport and cooling dynamics of such ballistic pyroclasts. In this study, we developed and coupled both a transport and a transient cooling model that account for the in-flight cooling of ballistic pyroclasts of different sizes, launch angles, and exit velocities. The transport model developed solves equations for a translating spherical body in two-dimensional (2-D) space, and our cooling model solves the Fourier heat equation for spherical bodies. Our two models were then coupled using a set of dimensionless equations that describe relationships between Nusselt-Reynolds-Prandtl numbers. These relationships provide a way to estimate the heat transfer coefficient, based on ambient flow conditions around the pyroclast, at different times during the pyroclast transport. Together, our coupled models can describe the trajectory, distance reached, viscosity changes, and cooling profiles (i.e., core to rim temperature) of pyroclasts during mafic explosive eruptions. As an example, we show how our model can be used to predict the temperature of pyroclasts within lava fountains with varying ambient temperatures and discuss the possible textural outcomes of ejected pyroclasts in-flight and upon landing. Thus, our model can be used to predict pyroclast types and textures (e.g., rheomorphic, breadcrusted) at set distances from the vent and used forensically to determine eruptive conditions from deposits of past eruptions.
{"title":"The in-flight cooling of ballistic pyroclasts during mafic explosive eruptions: a numerical model","authors":"Chiedozie C. Ogbuagu , Kuang C. Lin , Thomas J. Jones , Silvio De Angelis","doi":"10.1016/j.jvolgeores.2025.108463","DOIUrl":"10.1016/j.jvolgeores.2025.108463","url":null,"abstract":"<div><div>Explosive volcanic eruptions pose a threat to nearby populations and infrastructure. The erupted pyroclasts (i.e., variably molten droplets) can ballistically travel large distances from the vent, cause range of hazards, and produce a range of deposit types depending on the temperature at which they land. To mitigate these hazards and to perform enhanced quantitative textural analyses of the erupted pyroclasts, there is a need to improve our understanding of the transport and cooling dynamics of such ballistic pyroclasts. In this study, we developed and coupled both a transport and a transient cooling model that account for the in-flight cooling of ballistic pyroclasts of different sizes, launch angles, and exit velocities. The transport model developed solves equations for a translating spherical body in two-dimensional (2-D) space, and our cooling model solves the Fourier heat equation for spherical bodies. Our two models were then coupled using a set of dimensionless equations that describe relationships between Nusselt-Reynolds-Prandtl numbers. These relationships provide a way to estimate the heat transfer coefficient, based on ambient flow conditions around the pyroclast, at different times during the pyroclast transport. Together, our coupled models can describe the trajectory, distance reached, viscosity changes, and cooling profiles (i.e., core to rim temperature) of pyroclasts during mafic explosive eruptions. As an example, we show how our model can be used to predict the temperature of pyroclasts within lava fountains with varying ambient temperatures and discuss the possible textural outcomes of ejected pyroclasts in-flight and upon landing. Thus, our model can be used to predict pyroclast types and textures (e.g., rheomorphic, breadcrusted) at set distances from the vent and used forensically to determine eruptive conditions from deposits of past eruptions.</div></div>","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"468 ","pages":"Article 108463"},"PeriodicalIF":2.3,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145267510","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}
Pub Date : 2025-12-01Epub Date: 2025-09-30DOI: 10.1016/j.jvolgeores.2025.108459
Ítalo Payacán , Martín Meyer , Javier Reyes , Lorenzo Tavazzani , Rodrigo Quiroga , Javiera Muñoz , Francisco Gutiérrez , Sebastián Santibáñez
The reconstruction of long-term magmatic and eruptive evolution in arc settings is often limited by the incomplete preservation of volcanic stratigraphy, as sequences in active tectonic regions are commonly disrupted and eroded, making it difficult to link these variations to underlying geodynamic processes. This contribution presents a detailed reconstruction of the prolonged (∼6 Myr) volcanic evolution recorded in a dissected Miocene arc system, based on detailed stratigraphic analysis, whole-rock geochemistry, and U-Pb zircon geochronology. The >2500 m-thick volcanic succession documents diverse eruptive and compositional phases in three stratigraphic units, revealing remarkable changes in magma composition and eruptive style over time. The lower unit is composed of andesitic lavas and pyroclastic breccias, indicating explosive-effusive volcanism prior to 22.6 Ma. Zircon ages from the base of the middle unit confirms the onset of an episode dominated by rhyolitic domes between 22.6 and 18.6 Ma. This is followed by the construction of a composite andesite-basaltic edifice (upper unit), characterized by lava flows and volcanoclastic sequences, with the youngest zircon crystallization ages at ca.15 Ma. The enrichment in incompatible elements in rhyolitic and late andesitic rocks, combined with isotopic evidence for increased crustal assimilation and subducted sediments input within the source, points to a progressive modification of the magmatic system between 22 and 18 Ma. These geochemical and isotopic signatures coincide with the onset of a well-established crustal thickening event in central Chile during this period. This case illustrates how major magmatic changes and eruptive transitions can align with the transition from extensional to contractional tectonics within a single arc segment.
{"title":"Long-term compositional and eruptive transitions in an early Miocene volcanic system, Central Chile (33°S)","authors":"Ítalo Payacán , Martín Meyer , Javier Reyes , Lorenzo Tavazzani , Rodrigo Quiroga , Javiera Muñoz , Francisco Gutiérrez , Sebastián Santibáñez","doi":"10.1016/j.jvolgeores.2025.108459","DOIUrl":"10.1016/j.jvolgeores.2025.108459","url":null,"abstract":"<div><div>The reconstruction of long-term magmatic and eruptive evolution in arc settings is often limited by the incomplete preservation of volcanic stratigraphy, as sequences in active tectonic regions are commonly disrupted and eroded, making it difficult to link these variations to underlying geodynamic processes. This contribution presents a detailed reconstruction of the prolonged (∼6 Myr) volcanic evolution recorded in a dissected Miocene arc system, based on detailed stratigraphic analysis, whole-rock geochemistry, and U-Pb zircon geochronology. The >2500 m-thick volcanic succession documents diverse eruptive and compositional phases in three stratigraphic units, revealing remarkable changes in magma composition and eruptive style over time. The lower unit is composed of andesitic lavas and pyroclastic breccias, indicating explosive-effusive volcanism prior to 22.6 Ma. Zircon ages from the base of the middle unit confirms the onset of an episode dominated by rhyolitic domes between 22.6 and 18.6 Ma. This is followed by the construction of a composite andesite-basaltic edifice (upper unit), characterized by lava flows and volcanoclastic sequences, with the youngest zircon crystallization ages at <em>ca.</em>15 Ma. The enrichment in incompatible elements in rhyolitic and late andesitic rocks, combined with isotopic evidence for increased crustal assimilation and subducted sediments input within the source, points to a progressive modification of the magmatic system between 22 and 18 Ma. These geochemical and isotopic signatures coincide with the onset of a well-established crustal thickening event in central Chile during this period. This case illustrates how major magmatic changes and eruptive transitions can align with the transition from extensional to contractional tectonics within a single arc segment.</div></div>","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"468 ","pages":"Article 108459"},"PeriodicalIF":2.3,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145267511","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}
Pub Date : 2025-12-01Epub Date: 2025-09-27DOI: 10.1016/j.jvolgeores.2025.108458
Motohiro Sato , Masao Ban , Takashi Yuguchi , Tatsuya Adachi , Takumi Imura , Mirai Takebe
The framework of the magma plumbing system, its activation processes, and associated timescales were investigated based on the textures and compositions of volcanic crystals from the Okama pyroclastics (Okp, ca. 1200 CE to the 1894–1897 CE eruption) of the Zao volcano, northeastern Japan. The magmatic conditions were constrained using an integrated approach combining thermobarometry, hygrometry, and rhyolite-MELTS modelling. Less-evolved magma (M1, ∼250 MPa, ∼1125 °C, 2.0 wt% H2O, ∼50 wt% SiO2) was injected into the mushy shallow reservoir, which is predominantly composed of intermediate magma (M2, 150–250 MPa, ∼980 °C, 3.4 wt% H2O, ∼59 wt% SiO2) and evolved magma (M3, <150 MPa, <∼980 °C, 3.4–5.0 wt% H2O, >∼60 wt% SiO2) stored in the marginal part within the reservoir. The diversity of plagioclase zoning patterns reflects complex and multiple stages of mixing processes between these magmatic environments. Oscillatory zoning crystallised through cyclic changes in magmatic conditions. Patchy, coarsely sieve, and dusty zonings were formed from resorption induced by mafic magma recharge. Honeycomb plagioclase crystallised from supercooled less-evolved magma. Crystal system analysis applied to the plagioclase crystals revealed thermal and compositional heterogeneity within the shallow reservoir. This heterogeneity might be attributed to remobilisation of discrete parts within the mushy reservoir. Magnesium (Mg) diffusion modelling in plagioclase constrained the mixing-to-eruption timescales. The juxtaposition of highly diffused and undiffused Mg within individual crystals indicates both earlier-stage (approximately 10 to 200 years before the eruption) and pre-eruptive (less than 10 years) mixing episodes, suggesting that the shallow reservoir was ephemerally remobilised by the intermittent recharge.
{"title":"Mush remobilisation process during historical activity at the Zao volcano, northeastern Japan: Perspectives from plagioclase textures and compositions","authors":"Motohiro Sato , Masao Ban , Takashi Yuguchi , Tatsuya Adachi , Takumi Imura , Mirai Takebe","doi":"10.1016/j.jvolgeores.2025.108458","DOIUrl":"10.1016/j.jvolgeores.2025.108458","url":null,"abstract":"<div><div>The framework of the magma plumbing system, its activation processes, and associated timescales were investigated based on the textures and compositions of volcanic crystals from the Okama pyroclastics (Okp, ca. 1200 CE to the 1894–1897 CE eruption) of the Zao volcano, northeastern Japan. The magmatic conditions were constrained using an integrated approach combining thermobarometry, hygrometry, and rhyolite-MELTS modelling. Less-evolved magma (M<sub>1</sub>, ∼250 MPa, ∼1125 °C, 2.0 wt% H<sub>2</sub>O, ∼50 wt% SiO<sub>2</sub>) was injected into the mushy shallow reservoir, which is predominantly composed of intermediate magma (M<sub>2</sub>, 150–250 MPa, ∼980 °C, 3.4 wt% H<sub>2</sub>O, ∼59 wt% SiO<sub>2</sub>) and evolved magma (M<sub>3</sub>, <150 MPa, <∼980 °C, 3.4–5.0 wt% H<sub>2</sub>O, >∼60 wt% SiO<sub>2</sub>) stored in the marginal part within the reservoir. The diversity of plagioclase zoning patterns reflects complex and multiple stages of mixing processes between these magmatic environments. Oscillatory zoning crystallised through cyclic changes in magmatic conditions. Patchy, coarsely sieve, and dusty zonings were formed from resorption induced by mafic magma recharge. Honeycomb plagioclase crystallised from supercooled less-evolved magma. Crystal system analysis applied to the plagioclase crystals revealed thermal and compositional heterogeneity within the shallow reservoir. This heterogeneity might be attributed to remobilisation of discrete parts within the mushy reservoir. Magnesium (Mg) diffusion modelling in plagioclase constrained the mixing-to-eruption timescales. The juxtaposition of highly diffused and undiffused Mg within individual crystals indicates both earlier-stage (approximately 10 to 200 years before the eruption) and pre-eruptive (less than 10 years) mixing episodes, suggesting that the shallow reservoir was ephemerally remobilised by the intermittent recharge.</div></div>","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"468 ","pages":"Article 108458"},"PeriodicalIF":2.3,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145267509","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}
Pub Date : 2025-12-01Epub Date: 2025-09-30DOI: 10.1016/j.jvolgeores.2025.108451
Fernando J. Guerrero , Daniel Pérez-Zárate , Edgar Santoyo , Adrián Jiménez-Haro , David Yáñez-Dávila , Gustavo Santos-Raga
We present a conceptual and numerical description of CO and Radon (222Rn) transport in the geothermal system of Acoculco, Mexico. We build upon extensive CO flux measurements that have been conducted in the past and new CO flux and Rn concentration data collected during this investigation. The accumulation chamber method was employed for CO flux measurements, whereas Rn concentration derives from analysis of gas samples collected in active scintillation cells. Additionally, the structural setting in the study area is reinterpreted based on a geomorphological assessment. As a result, a 3D conceptual model of the CO and Rn is proposed and numerically modeled with the aid of TOUGHREACT V4. Our collected data confirm the existence of advective transport of CO and Rn within two sites known as Azufres and Alcaparrosa, with soil CO fluxes that can reach 30,000 g m−2day−1, and Rn concentrations as high as 12,000 Bq/m. In view of the relatively short half-life of 222Rn (3.8 days), the measured concentrations are indicative of localized permeable paths that connect with deep structures. Our numerical model represents adequately the non-isothermal diffusive transport of CO, while advective fluxes are not attained under simple darcian flow. Likewise, under a hypothesis of a deep Rn source (1200 m), with an initial molar ratio Rn/CO of 1, Rn concentrations drop rapidly (within 100 m from the source). Non-porous flow (channeling) and distributed sources of Rn arise as likely hypotheses to explain cold degassing in Acoculco.
{"title":"On the transport of CO2 and Radon in the geothermal area of Acoculco, Puebla, Mexico","authors":"Fernando J. Guerrero , Daniel Pérez-Zárate , Edgar Santoyo , Adrián Jiménez-Haro , David Yáñez-Dávila , Gustavo Santos-Raga","doi":"10.1016/j.jvolgeores.2025.108451","DOIUrl":"10.1016/j.jvolgeores.2025.108451","url":null,"abstract":"<div><div>We present a conceptual and numerical description of CO<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> and Radon (<sup>222</sup>Rn) transport in the geothermal system of Acoculco, Mexico. We build upon extensive CO<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> flux measurements that have been conducted in the past and new CO<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> flux and Rn concentration data collected during this investigation. The accumulation chamber method was employed for CO<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> flux measurements, whereas Rn concentration derives from analysis of gas samples collected in active scintillation cells. Additionally, the structural setting in the study area is reinterpreted based on a geomorphological assessment. As a result, a 3D conceptual model of the CO<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> and Rn is proposed and numerically modeled with the aid of TOUGHREACT V4. Our collected data confirm the existence of advective transport of CO<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> and Rn within two sites known as Azufres and Alcaparrosa, with soil CO<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> fluxes that can reach 30,000 g m<sup>−2</sup>day<sup>−1</sup>, and Rn concentrations as high as <span><math><mo>∼</mo></math></span>12,000 Bq/m<span><math><msup><mrow></mrow><mrow><mn>3</mn></mrow></msup></math></span>. In view of the relatively short half-life of <sup>222</sup>Rn (<span><math><mo>∼</mo></math></span>3.8 days), the measured concentrations are indicative of localized permeable paths that connect with deep structures. Our numerical model represents adequately the non-isothermal diffusive transport of CO<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>, while advective fluxes are not attained under simple darcian flow. Likewise, under a hypothesis of a deep Rn source (<span><math><mo>∼</mo></math></span>1200 m), with an initial molar ratio Rn/CO<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> of 1<span><math><mrow><mo>×</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>4</mn></mrow></msup></mrow></math></span>, Rn concentrations drop rapidly (within <span><math><mo>∼</mo></math></span>100 m from the source). Non-porous flow (channeling) and distributed sources of Rn arise as likely hypotheses to explain cold degassing in Acoculco.</div></div>","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"468 ","pages":"Article 108451"},"PeriodicalIF":2.3,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145221881","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}
Pub Date : 2025-12-01Epub Date: 2025-10-12DOI: 10.1016/j.jvolgeores.2025.108470
Ahmed Baamar , Ezzoura Errami , Brahim Karaoui , Zakarya Yajioui , John Browning
The study of dyke swarms is crucial for understanding the processes of magma intrusion and the tectonic environments that influence volcanic activity. Dyke swarms are essential records of tectonic and magmatic events, offering insights into magma ascent, chamber dynamics, and stress conditions during emplacement. In this context, the dyke swarm of the central part of the Saghro Massif (Eastern Anti-Atlas) is investigated for the first time, using structural aspects of the dykes and paleo stress inversion to constrain magma overpressure, the depth of magma reservoir, the state of stress during emplacement, and the tectonic regime responsible for emplacement. We selected seventy-eight mafic and intermediate dykes in the swarm of the Central Part of the Saghro Massif (CPSM), characterized by different orientations N-S to NNE-SSW, NE-SW, E-W and NW-SE. In addition, the size distribution of thicknesses and lengths follows a power-law and a log-normal distribution respectively. We calculate magmatic overpressure using selected dyke aspect ratios to estimate the depth of the magma reservoir. This study suggests that the CPSM dykes form mainly due to the injection of magma from a deep magma reservoir at depths >31 km, hence close to the Moho crust-mantle boundary (31–33 km). Paleo stress reconstruction shows that the CPSM dyke swarm was emplaced when the minimum principal compressive stress (σ3) was oriented WNW-ESE, and the maximum principal compressive stress (σ1) was vertical. The reconstruction also shows that the emplacement of the CPSM swarm occurred during a transtensional tectonic regime, associated with the WACadomian orogeny.
{"title":"Structural parameters of the late Ediacaran dyke swarm in the Saghro Massif (Eastern Anti-Atlas, Morocco): Implications for the depth of magma origin, paleo stress reconstruction and emplacement models","authors":"Ahmed Baamar , Ezzoura Errami , Brahim Karaoui , Zakarya Yajioui , John Browning","doi":"10.1016/j.jvolgeores.2025.108470","DOIUrl":"10.1016/j.jvolgeores.2025.108470","url":null,"abstract":"<div><div>The study of dyke swarms is crucial for understanding the processes of magma intrusion and the tectonic environments that influence volcanic activity. Dyke swarms are essential records of tectonic and magmatic events, offering insights into magma ascent, chamber dynamics, and stress conditions during emplacement. In this context, the dyke swarm of the central part of the Saghro Massif (Eastern Anti-Atlas) is investigated for the first time, using structural aspects of the dykes and paleo stress inversion to constrain magma overpressure, the depth of magma reservoir, the state of stress during emplacement, and the tectonic regime responsible for emplacement. We selected seventy-eight mafic and intermediate dykes in the swarm of the Central Part of the Saghro Massif (CPSM), characterized by different orientations N-S to NN<em>E</em>-SSW, NE-SW, E-W and NW-SE. In addition, the size distribution of thicknesses and lengths follows a power-law and a log-normal distribution respectively. We calculate magmatic overpressure using selected dyke aspect ratios to estimate the depth of the magma reservoir. This study suggests that the CPSM dykes form mainly due to the injection of magma from a deep magma reservoir at depths >31 km, hence close to the Moho crust-mantle boundary (31–33 km). Paleo stress reconstruction shows that the CPSM dyke swarm was emplaced when the minimum principal compressive stress (σ<sub>3</sub>) was oriented WNW-ESE, and the maximum principal compressive stress (σ<sub>1</sub>) was vertical. The reconstruction also shows that the emplacement of the CPSM swarm occurred during a transtensional tectonic regime, associated with the WACadomian orogeny.</div></div>","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"468 ","pages":"Article 108470"},"PeriodicalIF":2.3,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145333268","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}
Pub Date : 2025-12-01Epub Date: 2025-09-06DOI: 10.1016/j.jvolgeores.2025.108436
Sophie O. Vineberg , Paul G. Albert , Danielle McLean , Takehiko Suzuki , Yasuo Miyabuchi , Hideo Hoshizumi , Hannah M. Buckland , Gwydion Jones , Fumikatsu Nishizawa , Richard A. Staff , Keitaro Yamada , Ikuko Kitaba , Junko Kitagawa , Christina J. Manning , SG14 Project Members , Takeshi Nakagawa , Victoria C. Smith
Aso caldera in central Kyushu, SW Japan, is one of the largest and most active volcanoes in the world. The Aso system has experienced four caldera-forming eruptions (Aso-1 to -4) and inter-caldera activity from multiple central cones. This study provides detailed glass geochemistry of previously uncharacterised near-source, predominantly silicic, tephra units so that they can be correlated to ashfall layers preserved in distally located sedimentary records. Here the near-source glass data from twenty eruption deposits are integrated with the distal tephra fall deposits recorded in the high-resolution Lake Suigetsu record (situated approximately 525 km to the north-east), to better constrain the eruption timing, frequency, and ash dispersal of pre-30 ka Aso eruptions. The glass chemistry of these large Aso eruptions typically straddles the trachy-dacitic to rhyolitic compositional boundary. While some units share overlapping or similar glass chemistries, many can be distinguished from each other using major (SiO2, K2O, CaO and FeOt) and trace element (Sr) contents. The newly available near-source volcanic glass dataset has enabled the identification and correlation of an additional six tephra and cryptotephra deposits within the Lake Suigetsu record to known Aso eruptions. Consequently, nine of the twenty deposits in the Lake Suigetsu record (SG06/SG14 cores) displaying an Aso glass composition have now been correlated to near-source eruption units; these include, from youngest to oldest: Aso-Kpfa, Upper ACP4, Lower ACP4, ACP6, YmP5, Aso-4, Aso-ABCD, Aso-EF and Aso-HI. Significantly, the identification of these tephra deposits in Lake Suigetsu provides improved age estimates for the eruptions, and helps constrain the repose periods between eruptions; for instance ∼400 years are resolved between two eruptions associated with the ACP4 Plinian activities. Our integrated proximal-distal record also indicates a higher frequency of activity in the 10 kyrs leading up to Aso-4 caldera-forming eruption. Eleven Aso-derived eruption deposits in the Lake Suigetsu record have not yet been recognised in the exposed near-vent sequences, perhaps suggesting that Aso caldera has been responsible for more silicic high-intensity eruptions and widespread ashfall events than previously thought. This research demonstrates the merit of integrating proximal-distal records to better constrain eruption timing, frequencies and ash dispersals of pre-historic events.
{"title":"Revealing the timing and dispersal of large explosive eruptions at Aso volcano (Japan) by integrating proximal and distal tephra records over the last 130 kyrs","authors":"Sophie O. Vineberg , Paul G. Albert , Danielle McLean , Takehiko Suzuki , Yasuo Miyabuchi , Hideo Hoshizumi , Hannah M. Buckland , Gwydion Jones , Fumikatsu Nishizawa , Richard A. Staff , Keitaro Yamada , Ikuko Kitaba , Junko Kitagawa , Christina J. Manning , SG14 Project Members , Takeshi Nakagawa , Victoria C. Smith","doi":"10.1016/j.jvolgeores.2025.108436","DOIUrl":"10.1016/j.jvolgeores.2025.108436","url":null,"abstract":"<div><div>Aso caldera in central Kyushu, SW Japan, is one of the largest and most active volcanoes in the world. The Aso system has experienced four caldera-forming eruptions (Aso-1 to -4) and inter-caldera activity from multiple central cones. This study provides detailed glass geochemistry of previously uncharacterised near-source, predominantly silicic, tephra units so that they can be correlated to ashfall layers preserved in distally located sedimentary records. Here the near-source glass data from twenty eruption deposits are integrated with the distal tephra fall deposits recorded in the high-resolution Lake Suigetsu record (situated approximately 525 km to the north-east), to better constrain the eruption timing, frequency, and ash dispersal of pre-30 ka Aso eruptions. The glass chemistry of these large Aso eruptions typically straddles the trachy-dacitic to rhyolitic compositional boundary. While some units share overlapping or similar glass chemistries, many can be distinguished from each other using major (SiO<sub>2</sub>, K<sub>2</sub>O, CaO and FeO<sub>t</sub>) and trace element (Sr) contents. The newly available near-source volcanic glass dataset has enabled the identification and correlation of an additional six tephra and cryptotephra deposits within the Lake Suigetsu record to known Aso eruptions. Consequently, nine of the twenty deposits in the Lake Suigetsu record (SG06/SG14 cores) displaying an Aso glass composition have now been correlated to near-source eruption units; these include, from youngest to oldest: Aso-Kpfa, Upper ACP4, Lower ACP4, ACP6, YmP5, Aso-4, Aso-ABCD, Aso-EF and Aso-HI. Significantly, the identification of these tephra deposits in Lake Suigetsu provides improved age estimates for the eruptions, and helps constrain the repose periods between eruptions; for instance ∼400 years are resolved between two eruptions associated with the ACP4 Plinian activities. Our integrated proximal-distal record also indicates a higher frequency of activity in the 10 kyrs leading up to Aso-4 caldera-forming eruption. Eleven Aso-derived eruption deposits in the Lake Suigetsu record have not yet been recognised in the exposed near-vent sequences, perhaps suggesting that Aso caldera has been responsible for more silicic high-intensity eruptions and widespread ashfall events than previously thought. This research demonstrates the merit of integrating proximal-distal records to better constrain eruption timing, frequencies and ash dispersals of pre-historic events.</div></div>","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"468 ","pages":"Article 108436"},"PeriodicalIF":2.3,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145333274","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}
Pub Date : 2025-12-01Epub Date: 2025-09-01DOI: 10.1016/j.jvolgeores.2025.108434
Erick Juárez-Arriaga , Katrin Sieron , Harald Böhnel
High-precision paleomagnetic dating offers an independent and valuable tool for constraining the ages of Holocene volcanic eruptions - particularly when other dating methods are inapplicable yield uncertain results, or are contradicted by inconsistent historical records. We applied this approach to Pico de Orizaba (Citlaltépetl), a 5653 m stratovolcano in eastern Mexico that poses a significant threat to nearly half a million people living within a 30 km radius. Despite the existence of hazard maps, the eruptive chronology of the volcano remains poorly constrained due to contradictory and uncertain published data.
The study focused on Holocene lava flows, with sampling conducted at 35 sites across 12 distinct flows located at elevations between 3500 and 4800 m. We obtained robust paleomagnetic directions and absolute paleointensity values, which were compared to the SHA.DIF.14 k global geomagnetic model. This comparison enabled us to determine well-constrained emplacement ages, further supported by the available relative stratigraphic information.
Our results refine the Holocene eruptive history of Pico de Orizaba. We correlated two lava flows with previously determined 36Cl exposure ages, rejected earlier proposed historical attributions, and establish new correlations between flows on the northern and southern flanks. The eruptive record reveals two distinct phases interrupted by activity at the parasitic Chichimeco dome complex: (1) the Malacara lava flows, which followed the Citlaltépetl/Xilomich Plinian eruption, and (2) eruptions from approximately 2100 BCE to recent times. Both phases broadly coincide with periods of glacier retreat, suggesting a possible link between deglaciation and volcanic activity. These findings significantly improve the eruptive chronology of Pico de Orizaba and provide critical data for future hazard assessments.
高精度的古地磁测年为限制全新世火山爆发的年龄提供了一种独立而有价值的工具——特别是当其他测年方法不适用，产生不确定的结果，或者与不一致的历史记录相矛盾的时候。我们将这种方法应用于Pico de Orizaba (citlaltsametel)，这是墨西哥东部一座5653米的层状火山，对生活在30公里半径内的近50万人构成了重大威胁。尽管存在危险地图，但由于相互矛盾和不确定的公开数据，火山爆发的年表仍然很不严格。这项研究的重点是全新世熔岩流，在海拔3500至4800米的12个不同熔岩流的35个地点进行了采样。得到了稳健的古地磁方向和绝对古强度值，并与SHA.DIF进行了比较。14k全球地磁模型。这种比较使我们能够确定有良好约束的侵位年龄，并得到现有相对地层信息的进一步支持。我们的研究结果完善了Pico de Orizaba全新世喷发历史。我们将两个熔岩流与先前确定的36Cl暴露年龄进行了对比，拒绝了先前提出的历史归因，并在南北两侧的熔岩流之间建立了新的相关性。火山喷发记录显示，寄生奇希莫科穹隆复合体的活动中断了两个不同的阶段：(1)马拉卡拉熔岩流，紧随citlaltsamupetl /Xilomich Plinian火山喷发；(2)大约公元前2100年至最近的火山喷发。这两个阶段大致与冰川消退的时期一致，这表明冰川消融和火山活动之间可能存在联系。这些发现显著改善了Pico de Orizaba火山的喷发年表，并为未来的灾害评估提供了关键数据。
{"title":"Age of Holocene lava flows of Pico de Orizaba from paleomagnetic data","authors":"Erick Juárez-Arriaga , Katrin Sieron , Harald Böhnel","doi":"10.1016/j.jvolgeores.2025.108434","DOIUrl":"10.1016/j.jvolgeores.2025.108434","url":null,"abstract":"<div><div>High-precision paleomagnetic dating offers an independent and valuable tool for constraining the ages of Holocene volcanic eruptions - particularly when other dating methods are inapplicable yield uncertain results, or are contradicted by inconsistent historical records. We applied this approach to Pico de Orizaba (Citlaltépetl), a 5653 m stratovolcano in eastern Mexico that poses a significant threat to nearly half a million people living within a 30 km radius. Despite the existence of hazard maps, the eruptive chronology of the volcano remains poorly constrained due to contradictory and uncertain published data.</div><div>The study focused on Holocene lava flows, with sampling conducted at 35 sites across 12 distinct flows located at elevations between 3500 and 4800 m. We obtained robust paleomagnetic directions and absolute paleointensity values, which were compared to the SHA.DIF.14 k global geomagnetic model. This comparison enabled us to determine well-constrained emplacement ages, further supported by the available relative stratigraphic information.</div><div>Our results refine the Holocene eruptive history of Pico de Orizaba. We correlated two lava flows with previously determined 36Cl exposure ages, rejected earlier proposed historical attributions, and establish new correlations between flows on the northern and southern flanks. The eruptive record reveals two distinct phases interrupted by activity at the parasitic Chichimeco dome complex: (1) the Malacara lava flows, which followed the Citlaltépetl/Xilomich Plinian eruption, and (2) eruptions from approximately 2100 BCE to recent times. Both phases broadly coincide with periods of glacier retreat, suggesting a possible link between deglaciation and volcanic activity. These findings significantly improve the eruptive chronology of Pico de Orizaba and provide critical data for future hazard assessments.</div></div>","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"468 ","pages":"Article 108434"},"PeriodicalIF":2.3,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145050041","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}
Pub Date : 2025-12-01Epub Date: 2025-09-22DOI: 10.1016/j.jvolgeores.2025.108450
Paolo Fulignati , Anna Gioncada , Alessandro Aiuppa , Terry M. Seward , Richard W. Henley
The La Fossa cone on Vulcano island (Italy), like most active volcanoes, undergoes periodic phases of increased heat and gas discharge unrelated to surface magmatism. Variations in the major component chemistry of fumaroles during such cycles record the expansion and contraction of a magmatic vapor plume beneath the volcano in response to cycles of mafic magma intrusion several km below the surface and consequent changes in its interaction with surrounding meteoric water/seawater.
Using previously unpublished major and minor element fumarole data for the 1990's thermal crisis at La Fossa in conjunction with a primary mafic magma vapor composition derived from melt inclusion data and silicate melt-vapor partition coefficients, a thermochemical equilibrium model is developed to explain variations in fumarole gas chemistry in terms of subsurface gas-solid reactions during magmatic vapor expansion and dilution from source to surface. These reactions control total S and H2 through the production of anhydrite (CaSO4) and sulfide minerals. Pyrite, bismuthinite and sphalerite deposition, control the minor element composition of fumarole discharges. Most of the Cu is deposited as CuFe sulfides in the core of the expanding vapor plume so that it is not observed at surface. As is observed in fumarole sublimates, Au is deposited at low pressure in response to removal of H2S by sulfide deposition.
The thermochemical modelling results coupled with fumarole sublimate compositional data provide a metal zonation model for the interior of La Fossa that may be considered generic for other active volcanoes and their ancient equivalents.
{"title":"The 1990's thermal crisis at La Fossa volcano (Aeolian Islands, Italy): Systematics of magmatic vapor plume expansion and decay within an active volcano","authors":"Paolo Fulignati , Anna Gioncada , Alessandro Aiuppa , Terry M. Seward , Richard W. Henley","doi":"10.1016/j.jvolgeores.2025.108450","DOIUrl":"10.1016/j.jvolgeores.2025.108450","url":null,"abstract":"<div><div>The La Fossa cone on Vulcano island (Italy), like most active volcanoes, undergoes periodic phases of increased heat and gas discharge unrelated to surface magmatism. Variations in the major component chemistry of fumaroles during such cycles record the expansion and contraction of a magmatic vapor plume beneath the volcano in response to cycles of mafic magma intrusion several km below the surface and consequent changes in its interaction with surrounding meteoric water/seawater.</div><div>Using previously unpublished major and minor element fumarole data for the 1990's thermal crisis at La Fossa in conjunction with a primary mafic magma vapor composition derived from melt inclusion data and silicate melt-vapor partition coefficients, a thermochemical equilibrium model is developed to explain variations in fumarole gas chemistry in terms of subsurface gas-solid reactions during magmatic vapor expansion and dilution from source to surface. These reactions control total S and H<sub>2</sub> through the production of anhydrite (CaSO<sub>4</sub>) and sulfide minerals. Pyrite, bismuthinite and sphalerite deposition, control the minor element composition of fumarole discharges. Most of the Cu is deposited as CuFe sulfides in the core of the expanding vapor plume so that it is not observed at surface. As is observed in fumarole sublimates, Au is deposited at low pressure in response to removal of H<sub>2</sub>S by sulfide deposition.</div><div>The thermochemical modelling results coupled with fumarole sublimate compositional data provide a metal zonation model for the interior of La Fossa that may be considered generic for other active volcanoes and their ancient equivalents.</div></div>","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"468 ","pages":"Article 108450"},"PeriodicalIF":2.3,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145159452","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}
Pub Date : 2025-12-01Epub Date: 2025-09-30DOI: 10.1016/j.jvolgeores.2025.108456
Yemerith Alpízar-Segura , Guillermo E. Alvarado , Paulo Hidalgo , Peter C. Ryan , Deina Arroyo-Alpízar , Antonio Costa
<div><div>Barva is an andesitic shield volcano located 23 km north of San José (the capital of Costa Rica) and is the only eruptive center near the capital that until now, has no record of historical eruptions. Recent mapping around the summit indicates that at least eight explosive events (VEI 0–3) have occurred in the last 13 kyr. In the last 25 kyr, eruption of several summit and flank lava flows, and cones with basaltic andesite to andesitic composition were interspersed with prolonged dormancy periods. The most important and well-known lava field (12.8 km<sup>2</sup>) erupted from the basaltic andesitic Monte de la Cruz cinder cone about 17 kyr on the South-southwest flank. The explosive deposits confined to the summit area (within a radius of 10 km around the highest cones at 2906 m a.s.l.) range from a lower tephra fall deposit layer dated at ∼13,300 yr BP (from Guararí cone) to the most recent strombolian event around ∼250 yr BP (ca. 1700 CE) from Urás cone. During the Holocene, the volcano has experienced at least one subplinian (≥6 × 10<sup>6</sup> m<sup>3</sup> DRE) and one strombolian eruption (∼3 × 10<sup>6</sup> m<sup>3</sup> DRE), with frequent eruptions whose deposits are consistent with the vulcanian style (between ∼2 × 10<sup>6</sup> and ∼3.1 × 10<sup>6</sup> m<sup>3</sup> DRE) originating from several small cones and craters at the summit. Periods of dormancy vary between ∼750 and ∼3820 yr, with approximately 325 yr of quiescence since the last small-volume eruption for which there are no written records due the low population density during the middle of the seventeenth century and its normal cloudy conditions. Results of our radiometric and field data analysis indicate that if explosions similar to those that happened in the past 13 kyr occur in the coming centuries, there could be an impact on the towns near the volcano (about 1200 people), mainly due to pyroclastic flows, ashfall and gas dispersion, while at the country level, the main impact would be due to the dispersion and ashfall.</div></div><div><h3>Resumen</h3><div>Barva es un volcán en escudo andesítico ubicado a 23 km al norte de San José (la capital de Costa Rica) y es el único centro eruptivo cerca de la capital que, hasta ahora, no tiene registro de erupciones históricas. El mapeo reciente alrededor de la cumbre indica que al menos ocho eventos explosivos (VEI 0 – 3) han ocurrido en los últimos 13 ka. En los últimos 25 ka, la erupción de varios flujos de lava de cumbre y flanco y conos con composición basáltica de andesita a andesítica se intercaló con períodos prolongados de reposo. El campo de lava más importante y conocido (12,8 km<sup>2</sup>) entró en erupción a partir del cono de ceniza andesítico basáltico del Monte de la Cruz a unos 17 ka en el flanco sur-suroeste. Los depósitos explosivos confinados en el área de la cumbre (dentro de un radio de 10 km alrededor de los conos más altos a 2906 m s.n.m.) van desde una capa de depósito de caída de tefra infe
巴尔瓦火山是一座安山岩盾状火山，位于哥斯达黎加首都圣何塞以北23公里处，是首都附近唯一一个迄今为止没有历史喷发记录的喷发中心。最近在峰会周围绘制的地图显示，在过去13年中，至少发生了8起爆炸性事件（VEI 0-3）。近25年来，数次峰顶和侧翼熔岩流喷发，玄武岩安山岩-安山岩组成的火山锥穿插着较长的休眠期。最重要和最著名的熔岩场（12.8平方公里）喷发自位于西南偏南约17公里的玄武岩安山岩蒙德拉克鲁兹火山渣锥。爆炸沉积局限于峰顶区域（在海拔2906米的最高锥周围半径10公里范围内），范围从可追溯到~ 13300年BP（来自Guararí锥）的较低的tephra fall沉积层到最近的约250年BP（约1700年）的Urás锥的strombolian事件。在全新世期间，火山经历了至少一次亚斜喷发（≥6 × 106 m3 DRE）和一次斯特隆波利喷发（~ 3 × 106 m3 DRE），频繁的喷发与火山风格（在~ 2 × 106和~ 3.1 × 106 m3 DRE之间）一致，起源于山顶的几个小锥和陨石坑。休眠期在~ 750年到~ 3820年之间变化，自上一次小体积喷发以来大约有325年的静止期，由于17世纪中叶的低人口密度和正常的多云条件，没有书面记录。我们的辐射测量和现场数据分析结果表明，如果在未来几个世纪发生类似于过去13年发生的爆炸，火山附近的城镇（约1200人）可能会受到影响，主要是由于火山碎屑流、火山灰和气体分散，而在国家一级，主要影响将是由于分散和火山灰。简历barva的网址为volcán en escudo andesítico ubicado位于圣何塞北部23公里处（哥斯达黎加首都），网址为único首都火山喷发中心，hasta ahora， no tiene registro de火山喷发históricas。El mapeo收件人已经获得了关于爆炸事件的爆炸事件（VEI 0 - 3）和爆炸事件（últimos 13 ka）的数据。En los últimos 25 ka, la erupción de varios flujos de lava de cumberberi flanco de conconcomposición basáltica de andesita a andesítica se intercaló conperíodos prolongados de reposo。El campo de lava más important y conocido（12,8平方公里）entró en erupción a partipartir del cono de ceniza andesítico basáltico del Monte de la Cruz和unos 17 ka en El franco sur-suroeste。洛杉矶depositos explosivos confinados en el区域de la山峰(dentro de联合国电台de 10公里alrededor de Los conos mas女低音2906 s.n.m)。van de deposito desde una卡帕de caida de tefra劣质fechada en∼13300岁美国专利。(desde el cono de Guarari)直到el evento estromboliano mas reciente alrededor de∼250岁美国专利(cono de ura所言)。Durante el Holoceno, el volcán ha experimentado al menos una erupción subpliniana（≥6 × 106 m3 DRE）与una estromboliana (~ 3 × 106 m3 DRE), con erupciones frerecentes cuyo depósitos son consistes con el estilo vulcaniano（中心~ 2 × 106 y ~ 3.1 × 106 m3 DRE） que se originan en varios conos y cráteres pequeños en la cumbre。Los períodos de latencia varían entre ~ 750 y ~ 3820 años, con proximadamente 325 años de inactividad desde la última erupción de pequeño voluumen para la cual no hay registros escritos debido a la baja densidad de población existente a mediados del siglo 17 y sus condiones nubladas normales。洛杉矶resultados de Los分析radiometricos y de拿督de campo糖苷,如果在洛杉矶下月的siglos se producen爆炸类似一个拉斯维加斯ocurridas在洛杉矶上月的13 ka, podria haber联合国impacto在拉斯维加斯poblaciones cercanas al (una 1200角色),血管疾病所对应变窄piroclasticos, caida de ceniza y de气体分散,mientras,坏胆固醇pais, el主要impacto se deberia la色散y caida de ceniza。
{"title":"Decoding Barva volcano: 26,700 years of eruptions and hazard implications","authors":"Yemerith Alpízar-Segura , Guillermo E. Alvarado , Paulo Hidalgo , Peter C. Ryan , Deina Arroyo-Alpízar , Antonio Costa","doi":"10.1016/j.jvolgeores.2025.108456","DOIUrl":"10.1016/j.jvolgeores.2025.108456","url":null,"abstract":"<div><div>Barva is an andesitic shield volcano located 23 km north of San José (the capital of Costa Rica) and is the only eruptive center near the capital that until now, has no record of historical eruptions. Recent mapping around the summit indicates that at least eight explosive events (VEI 0–3) have occurred in the last 13 kyr. In the last 25 kyr, eruption of several summit and flank lava flows, and cones with basaltic andesite to andesitic composition were interspersed with prolonged dormancy periods. The most important and well-known lava field (12.8 km<sup>2</sup>) erupted from the basaltic andesitic Monte de la Cruz cinder cone about 17 kyr on the South-southwest flank. The explosive deposits confined to the summit area (within a radius of 10 km around the highest cones at 2906 m a.s.l.) range from a lower tephra fall deposit layer dated at ∼13,300 yr BP (from Guararí cone) to the most recent strombolian event around ∼250 yr BP (ca. 1700 CE) from Urás cone. During the Holocene, the volcano has experienced at least one subplinian (≥6 × 10<sup>6</sup> m<sup>3</sup> DRE) and one strombolian eruption (∼3 × 10<sup>6</sup> m<sup>3</sup> DRE), with frequent eruptions whose deposits are consistent with the vulcanian style (between ∼2 × 10<sup>6</sup> and ∼3.1 × 10<sup>6</sup> m<sup>3</sup> DRE) originating from several small cones and craters at the summit. Periods of dormancy vary between ∼750 and ∼3820 yr, with approximately 325 yr of quiescence since the last small-volume eruption for which there are no written records due the low population density during the middle of the seventeenth century and its normal cloudy conditions. Results of our radiometric and field data analysis indicate that if explosions similar to those that happened in the past 13 kyr occur in the coming centuries, there could be an impact on the towns near the volcano (about 1200 people), mainly due to pyroclastic flows, ashfall and gas dispersion, while at the country level, the main impact would be due to the dispersion and ashfall.</div></div><div><h3>Resumen</h3><div>Barva es un volcán en escudo andesítico ubicado a 23 km al norte de San José (la capital de Costa Rica) y es el único centro eruptivo cerca de la capital que, hasta ahora, no tiene registro de erupciones históricas. El mapeo reciente alrededor de la cumbre indica que al menos ocho eventos explosivos (VEI 0 – 3) han ocurrido en los últimos 13 ka. En los últimos 25 ka, la erupción de varios flujos de lava de cumbre y flanco y conos con composición basáltica de andesita a andesítica se intercaló con períodos prolongados de reposo. El campo de lava más importante y conocido (12,8 km<sup>2</sup>) entró en erupción a partir del cono de ceniza andesítico basáltico del Monte de la Cruz a unos 17 ka en el flanco sur-suroeste. Los depósitos explosivos confinados en el área de la cumbre (dentro de un radio de 10 km alrededor de los conos más altos a 2906 m s.n.m.) van desde una capa de depósito de caída de tefra infe","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"468 ","pages":"Article 108456"},"PeriodicalIF":2.3,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145267512","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}
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