Journal of Volcanology and Geothermal Research最新文献_第6页

Modelling magma flow within dyke-fed sill geometries: A coupled thermal and fluid dynamics approach 岩浆流动在岩脉供给的岩石几何模型：热学和流体动力学的耦合方法

IF 2.3 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Volcanology and Geothermal Research

Pub Date : 2026-01-01 Epub Date: 2025-10-25 DOI: 10.1016/j.jvolgeores.2025.108480

K.M. Williams , A. Geyer , C. Annen , J. Kavanagh

Sill geometry and magma flow indicators preserved within fossil sills are used to determine magma source locations, understand economic potential of magmatic ore deposits, and forecast potential volcanic eruption sites. However, existing models struggle to incorporate complex flow dynamics and quantify flow variability, thus inhibiting their potential to explain spatially variable magma flow within sills spanning up to hundreds of kilometres. We present results of new 2D finite element numerical simulations coupling fluid and thermal dynamics within a dyke-fed sill using a multiphysics approach. As magma enters the model sill from below via one (or several) feeding dyke(s), magma jets of variable height develop within the sill depending on dyke thickness and inlet velocity. Low-velocity zones occur near the feeding dyke(s), with recirculation present between multiple feeding dyke(s) when they are present. These findings demonstrate the significant impact that intrusion geometry has on the magma flow dynamics within the sill, and we postulate that the presence of magma jets at the dyke-to-sill transition may be one source of sill lobes. They suggest random crystal orientations could be expected close to feeder dykes (low-velocity recirculating flow and rapid solidification), but where strain rates are high crystal alignment may still occur. These results potentially explain complex magma flow as interpreted from field observations and petrographic analysis of sill. Our results show that incorporating intrusion geometries, flow dynamics and thermal processes into models is crucial for bridging the gap between field observations and the underlying processes that govern natural systems.

在化石岩床中保存的岩床几何和岩浆流动指标用于确定岩浆源位置，了解岩浆矿床的经济潜力，预测潜在的火山爆发地点。然而，现有的模型难以纳入复杂的流动动力学和量化流动变异性，从而抑制了它们解释跨越数百公里的断层内空间变化的岩浆流动的潜力。我们提出了新的二维有限元数值模拟的结果，耦合流体和热动力学在一个多物理场的方法在一个堤上馈送的仍然。当岩浆通过一个（或几个）进料堤从底部进入模型岩床时，根据岩床厚度和入口速度的不同，在岩床内形成不同高度的岩浆射流。低速带出现在进料堤附近，当多个进料堤存在时，在它们之间存在再循环。这些发现表明，侵入体的几何形状对基底内岩浆流动动力学有显著的影响，我们假设岩浆喷流的存在可能是基底裂片的一个来源。他们认为，晶体的随机取向可能接近给料墙（低速再循环流动和快速凝固），但在应变率高的地方，晶体取向仍然可能发生。这些结果可能解释了从野外观测和岩相分析中解释的复杂岩浆流。我们的研究结果表明，将入侵几何、流动动力学和热过程纳入模型对于弥合野外观测与控制自然系统的潜在过程之间的差距至关重要。

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引用次数: 0

Rates of plagioclase growth, nanolite nucleation, and viscosity increase during Vulcanian activity of Sakurajima Volcano, Japan 日本樱岛火山活跃期斜长石生长速率、纳米石成核速率和黏度增加速率

IF 2.3 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Volcanology and Geothermal Research

Pub Date : 2026-01-01 Epub Date: 2025-11-04 DOI: 10.1016/j.jvolgeores.2025.108483

Aulia Syafitri , Michihiko Nakamura , Naoki Araya , Mayumi Mujin , Daisuke Miki , Masato Iguchi

This study investigated the products of successive Vulcanian eruptions in 1976 at the Minamidake summit crater of the Sakurajima Volcano, namely pumice clasts from an explosion on May 13 and dense juvenile fragments from May 17. Effective undercooling (ΔT_eff) on May 11–13 and 13–17 were estimated at 53–86 and 33–45 °C, respectively. Plagioclase phenocrysts exhibited broken surfaces with regrowth rims, which were attributed to decompression by the immediately preceding explosions. Based on the regrowth rim widths, the average growth rates were estimated to be 0.4–1.7 × 10⁻¹¹ and 1.7–4.7 × 10⁻¹² m s⁻¹ on May 11–13 and 13–17, respectively, suggesting silicon diffusion-controlled growth. These growth rates were consistent with those from previous decompression experiments at similar ΔT_eff under the same conditions (i.e., temperature and melt SiO₂ and H₂O content) as Sakurajima. Assuming that plagioclase nanolites and fine-grained microlites with lengths shorter than the regrowth rims widths nucleated in the corresponding periods, the nucleation rate measured on May 11–13 agreed well with the recalculated experimental rates. In contrast, the nucleation rate measured on May 13–17 was higher by at least 1.9 orders of magnitude, suggesting nucleation acceleration at a pressure of <40 MPa. The high nucleation rates increased the groundmass total crystallinity by a factor of 2–5 compared with the experiments at similar ΔT_eff, enabling the groundmass viscosity to reach the stress fragmentation threshold for a Vulcanian explosion. A precise understanding of these shallow magma crystallization kinetics thus paves the way for prediction of eruptive styles.

本研究调查了1976年樱岛火山Minamidake山顶火山口连续火山喷发的产物，即5月13日爆炸的浮石碎屑和5月17日密集的幼体碎片。5月11-13日和13-17日的有效过冷（ΔTeff）估计分别为53-86°C和33-45°C。斜长石斑晶表现出破碎的表面和再生的边缘，这是由于之前的爆炸造成的减压。根据再生环宽度估算，5月11 - 13日和13-17日的平均生长率分别为0.4-1.7 × 10−11和1.7-4.7 × 10−12 m s−1，表明硅的扩散控制生长。这些生长速率与先前在类似ΔTeff条件下（即温度和熔体SiO2和H2O含量）与Sakurajima相同的减压实验一致。假设长度小于再生棱宽的斜长石纳米岩和细粒微岩在相应时期成核，则5月11-13日测量的成核速率与重新计算的实验速率吻合较好。而5月13日至17日的成核速率至少提高了1.9个数量级，表明在40 MPa的压力下成核加速。与类似ΔTeff条件下的实验相比，高成核率使地面物质的总结晶度提高了2-5倍，使地面物质粘度达到了火山爆发的应力破碎阈值。因此，对这些浅层岩浆结晶动力学的精确理解为预测喷发风格铺平了道路。

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引用次数: 0

A classification scheme for olivine populations in the Upper Pleistocene to Holocene Igwisi Hills (Tanzania) kimberlite lavas and investigation of grain origins and evolution 坦桑尼亚Igwisi Hills金伯利岩浆岩上更新世至全新世橄榄石种群分类方案及颗粒起源与演化研究

IF 2.3 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Volcanology and Geothermal Research

Pub Date : 2026-01-01 Epub Date: 2025-11-21 DOI: 10.1016/j.jvolgeores.2025.108497

J.J. Rawlings , T.M. Gernon , M.J. Stock , M.R. Palmer , C.M. Petrone , R.J. Brown , E. Humphreys-Williams

Kimberlites are a class of alkaline igneous rock which sometimes contain diamonds and derive from mantle depths typically exceeding 150 km. We investigate the Upper Pleistocene to Holocene (12 ka) Igwisi Hills kimberlites to characterise the olivine grains and better understand their origins and evolution. We observe four distinct olivine populations. Macrocrysts are >1500 μm in diameter, rounded, monocrystalline grains with a Mg-rich xenocrystic core (Fo 90.5–92.8) and elevated Ni but depleted Ca and Mn contents, typical of granular mantle peridotite. Nodules are >1500 μm in diameter, rounded, polycrystalline grains with an Mg-rich core (Fo 91–92.4), also derived from granular peridotite. Microcryst grains are <1500 μm, subhedral-euhedral and can be subdivided into two types. Microcryst-a grains have a Mg-rich (Fo 90–92.5) xenocrystic core indicative of a mantle peridotite origin and microcryst-b grains have a Fe-rich (Fo 89–91) core that likely originated from disaggregated neoblasts. Olivine in all four populations displays four magmatic zones: internal zone, rim, rind and outermost rind, typical of kimberlites worldwide. Fe-rich internal zones are likely derived from a primitive kimberlite melt which entrained the cores. Mg-rich rims formed as the kimberlite melt evolved and crystallised around the internal zones. Fe-rich rinds formed as the kimberlite melt continued to ascend and further crystallised around the rims. Mg-rich outermost rinds crystallised from the kimberlite melt during the final stages of ascent. Based on these observations we present a new ascent model for the Igwisi Hills magmas.

金伯利岩是一类碱性火成岩，有时含有钻石，来自地幔深度通常超过150公里。我们研究了上更新世至全新世（12 ka） Igwisi Hills金伯利岩，以表征橄榄石颗粒，并更好地了解它们的起源和演化。我们观察到四种不同的橄榄石种群。大晶为直径1500 μm的圆形单晶，芯部为富镁异晶（Fo值90.5 ~ 92.8），Ni含量升高，Ca、Mn含量下降，为典型的粒状地幔橄榄岩。结核是直径1500 μm的圆形多晶颗粒，芯部富mg (Fo 91-92.4)，也来源于粒状橄榄岩。微晶晶粒尺寸为<；1500 μm，亚面形-自面形，可分为两种类型。微晶a颗粒具有富镁（Fo 90-92.5）的异晶核，表明其可能起源于地幔橄榄岩；微晶b颗粒具有富铁（Fo 89-91）的核，可能起源于分裂的新母细胞。四个种群的橄榄石均显示出四个岩浆带：内带、边缘带、外皮带和最外皮带，是全球金伯利岩的典型特征。富铁的内部带可能来自原始的金伯利岩熔体，它带走了岩心。当金伯利岩融化并在内部区域结晶时，富含镁元素的边缘形成了。随着金伯利岩的融化继续上升并在边缘周围进一步结晶，富铁的外壳形成了。在上升的最后阶段，富含镁元素的最外层由金伯利岩熔体结晶。在此基础上，我们提出了一种新的伊格维西火山岩浆上升模型。

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引用次数: 0

Detailed resistivity structure by high-density AMT surveys in the geothermal area: A case study near Unzen volcanoes, Japan 地热区高密度AMT测量的详细电阻率结构：以日本云仙火山附近为例

IF 2.3 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Volcanology and Geothermal Research

Pub Date : 2026-01-01 Epub Date: 2025-10-08 DOI: 10.1016/j.jvolgeores.2025.108466

Nagi Yamashita , Tada-nori Goto , Keiichi Ishizu , Kodo Umakoshi , Hiroshi Sasaki

Hydrothermal fluids are well known to circulate through fracture zones (e.g., faults) in geothermal areas. Impermeable clay layers can play a role of caprock, retaining geothermal reservoirs underneath. Hydrothermal alteration layers are known to include clay minerals and to have lower hydraulic permeability and higher electrical conductivity than the surrounding rocks. The magnetotelluric (MT) method of geophysical exploration can estimate the resistivity structure below the surface. Therefore, MT method can reveal relations among hydrothermal fluid circulation, impermeable clay layers, and faults. Nevertheless, because of sparseness of observation sites and the resulting low spatial resolution, earlier studies using the MT method have rarely revealed such detailed relations. For this study, high-density audio-frequency MT (AMT) soundings were conducted at 83 sites in the Unzen hot spring area, Japan, with site spacing of approximately 50–150 m to estimate details of the three-dimensional (3-D) resistivity structure near the surface (shallower than 1 km). Consequently, the distribution of conductive bodies was clearly identified in the shallow subsurface. Some conductive bodies are exposed on the surface, where hot springs and fumaroles are distributed. The conductive bodies are regarded as representing hydrothermal alteration layers. However, no shallow conductive body was found on the north side of an active fault (Oshidori-no-ike fault; OF). This feature suggests sharp variation of subsurface temperatures at OF, possibly because of recharging of meteoric water along OF. We conclude that high-density 3-D AMT surveys can reveal shallow subsurface geothermal systems.

众所周知，热液流体在地热区的断裂带（如断层）中循环。不透水的粘土层可以起到盖层的作用，保留地下的地热储层。已知热液蚀变层含有粘土矿物，并且比围岩具有较低的水力渗透率和较高的导电性。地球物理勘探中的大地电磁法可以估计地表以下的电阻率结构。因此，MT方法可以揭示热液流体循环、不渗透粘土层和断层之间的关系。然而，由于观测点的稀疏性和由此产生的低空间分辨率，使用MT方法的早期研究很少揭示这种详细的关系。本研究在日本云禅温泉地区的83个测点进行高密度音频MT （AMT）测深，测点间距约为50-150 m，以估计地表附近（浅于1 km）的三维电阻率结构细节。从而明确了浅层地下导电体的分布。一些导电体暴露在地表，地表分布着温泉和喷气孔。导电体被认为是热液蚀变层的代表。而在活动断层（oshidori -no- like fault; of）的北侧未发现浅层导电体。这一特征表明of的地下温度变化剧烈，可能是由于沿of的大气水补给所致。我们认为高密度三维AMT测量可以揭示浅层地下地热系统。

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引用次数: 0

Does pre-ascent magma storage influence eruption style? An evaluation from textures and geochemistry of phenocrysts at Taranaki volcano 上升前的岩浆储存是否影响喷发风格？塔拉纳基火山斑晶结构及地球化学评价

IF 2.3 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Volcanology and Geothermal Research

Pub Date : 2026-01-01 Epub Date: 2025-11-25 DOI: 10.1016/j.jvolgeores.2025.108502

Phil Shane , Shanice Mascarenhas , Teresa Ubide , Shane J. Cronin

Understanding the explosivity of future volcanic eruptions is a cornerstone of hazard evaluation, and magma storage days to years leading up to eruption could provide timely information for mitigation strategies. To explore the influence of pre-ascent conditions on eruption style we compared the growth histories of plagioclase and amphibole phenocrysts from four prominent, Holocene-aged, explosive erupted deposits with six effusive eruptions at Taranaki volcano, New Zealand. The explosively erupted andesite-dacite magmas display a range of bulk compositions and crystallinities that overlap with those erupted effusively. Regardless of their eruption style, each phenocryst population displays a high degree of inter-crystal textural, geochemical and Sr-isotope discordance, including in their final rim growth. This can be explained by the periodic intrusive disruption of a redeveloping crystal mush that lacked a unidirectional assimilation-fractional-crystallisation path in the centuries to millennia between eruptions. However, amphiboles from most of the effusive eruptions are distinguished from those erupted explosively by recording late-stage halogen (and likely other volatiles) accumulation in the magma and subsequent decomposition during slow ascent. Also more prevalent in the effusive eruptions are plagioclase textures that record late-stage mingling with a mafic melt. These features support conceptual models that suggest magma compressibility due to volatile accumulation allows more efficient magma mingling during recharge and thus heating. The resulting melt viscosity reduction and enhanced outgassing of the magma then promotes effusive eruption. Testing this hypothesis via mineralogical determination of intensive parameters would need to overcome the high degree of disequilibrium that occurred at all stages of the magma evolution.

了解未来火山爆发的爆炸性是危险评估的基石，而火山爆发前几天到几年的岩浆储存可以为减灾战略提供及时的信息。为了探讨上升前条件对喷发类型的影响，我们比较了新西兰Taranaki火山4个突出的全新世爆发矿床的斜长石和角闪孔斑晶的生长历史。爆炸喷发的安山岩-英安岩岩浆显示出一系列的体积成分和结晶度，与那些喷涌喷发的岩浆重叠。无论其喷发方式如何，每个斑晶种群都表现出高度的晶间结构、地球化学和sr同位素不一致，包括在它们最终的边缘生长中。这可以解释为，在火山爆发之间的几个世纪到几千年间，重新发育的晶体混合物缺乏单向的同化-部分-结晶路径，因此会出现周期性的侵入性破坏。然而，通过记录晚期卤素（以及其他可能的挥发物）在岩浆中的积累和随后缓慢上升过程中的分解，大多数喷涌喷发的角闪石与爆炸喷发的角闪石区别开来。此外，在喷涌喷发中更为普遍的是斜长石结构，它记录了晚期与镁质熔体的混合。这些特征支持了一些概念模型，即岩浆可压缩性是由挥发性积累引起的，这使得岩浆在补给和加热过程中更有效地混合在一起。由此导致的熔体粘度降低和岩浆释放气体增强，进而促进了喷涌式喷发。通过对密集参数的矿物学测定来验证这一假设，需要克服在岩浆演化的各个阶段都存在的高度不平衡。

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引用次数: 0

Delineation of a geothermal source beneath the Panamik-Changlung Hot Springs along the Karakoram Fault, Ladakh, India, using magnetotelluric studies

IF 2.3 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Volcanology and Geothermal Research

Pub Date : 2025-12-01 Epub Date: 2025-10-21 DOI: 10.1016/j.jvolgeores.2025.108478

Prasanta K. Patro , S. Dhamodharan , Venkata Durga , K.K. Abdul Azeez , Narendra Babu , K. Chinna Reddy , Arvind K. Gupta , M. Shiva Krishna

The Panamik–Changlung hot springs, located along the Karakoram Fault (KF) in the Trans-Himalayan region of Ladakh in India, were investigated for the first time using the Magnetotelluric (MT) method to assess their geoelectrical properties. Situated in the Shyok–Nubra Valley between the Ladakh and Karakoram Batholiths, the region shows abundant geothermal manifestations. We acquired MT data along a 30 km profile parallel to the KF and performed 3D joint inversion of the impedance tensor and tipper data using the ModEM program. The resulting resistivity model reveals an upper crustal conductor (<10 Ω.m) at 4–10 km depth acting as geothermal reservoir with strong out-of-quadrant phases (>90° at periods >10 s) indicate a more complex system, potentially involving current channeling and electrical anisotropy. A shallower conductor (surface to ∼1.5 km) corresponds to sediments of Nubra Formation and fractured zones of the Karakoram Metamorphic Complex saturated with mixed thermal fluids and groundwater.

我们沿着平行于KF的30 km剖面获取了MT数据，并使用ModEM程序对阻抗张量和倾斜度数据进行了三维联合反演。所得到的电阻率模型显示，4-10 km深度的上地壳导体（<10 Ω.m）作为地热储层，具有强的象限外相（>90°，周期>；10 s），表明一个更复杂的系统，可能涉及电流通道和电性各向异性。较浅的导体（地表至~ 1.5 km）对应于Nubra组的沉积物和喀喇昆仑变质杂岩的裂缝带，其中混合热流体和地下水饱和。

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引用次数: 0

Pillow flows of rhyolite rheoignimbrite exposed in the Fukube Falls, Hakusan-Shirakawago White Road 白川白川白路，福部瀑布中暴露的流纹岩流光斑枕状水流

IF 2.3 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Volcanology and Geothermal Research

Pub Date : 2025-12-01 Epub Date: 2025-09-15 DOI: 10.1016/j.jvolgeores.2025.108444

Susumu Umino

The Fukube Falls in the upper Jadani River exposes successive layers of essentially subaerial ignimbrite of the 70 Ma Futomiyama Group, that intervenes a rheoignimbrite layer of giant pillows. The pillowed layer extends 320 m from east to west and varies in thickness from 15 m to 84 m. The bifurcating pillow lobes indicate that the western, central and eastern pillows flowed southward, eastward and southwestward, respectively. The pillow lobes range from 1 to more than 9 m in height and from 1 to 13 m in width, with an average of 3.4 ± 1.6 m and 4.2 ± 2.1 m, respectively. The height/width ratio is 0.78, which is similar to the ranges for tholeiite pillows of the Recent Loihi Seamount, Hawaii, and larger than those of the Cretaceous Oman Ophiolite. The obsidian glass of the pillow margin has a rhyolitic composition with 77 mass% SiO₂. The magma temperature is estimated from 782 °C to 810 °C, depending on the water content, based on the hornblende geothermometer. Analogue experiments on pillow lobe height constrain the upper and lower limits of extrusion rate and viscosity of the rheoignimbrite. In addition, the Devorah number, the ratio of rate of strain accumulation to the rate of strain relaxation, also gives the maximum viscosity and extrusion rate that allows for the formation of coherent pillows without fragmentation. Based on these constraints, the conditions of pillow lobe formation are viscosities ranging from 10^4.5 Pa·s to 10^6.8 Pa·s, and extrusion rates from 2.4 × 10⁻³ m³/s to 3.1 × 10³ m³/s for point sources and from 2.4 × 10⁻³ m²/s to 3.1 × 10² m²/s for line sources. Such viscosities require water contents of the magma more than 1.4 mass%, suggesting the hydrous welding of ignimbrite that was initially extruded on land and was emplaced under water-saturated conditions.

位于Jadani河上游的Fukube瀑布暴露了70 Ma Futomiyama群的连续层，这些层基本上是地面上的点烟煤，它与巨大枕头的流质点烟煤层相穿插。枕状层从东到西长320米，厚度从15米到84米不等。枕叶分叉表明西枕、中枕和东枕分别向南、向东和西南流动。枕瓣高度1 ~ 9 m以上，宽度1 ~ 13 m，平均分别为3.4±1.6 m和4.2±2.1 m。高宽比为0.78，与夏威夷Loihi海山近代拉斑岩枕的范围相似，大于白垩纪阿曼蛇绿岩枕的范围。枕缘黑曜石玻璃为流纹岩成分，SiO2质量% 77。根据角闪石地温计，根据含水量的不同，岩浆温度估计在782℃至810℃之间。枕瓣高度的模拟实验约束了流变镁的挤出速率和粘度的上下限。此外，德沃拉数，应变积累率与应变松弛率之比，也给出了最大粘度和挤出率，允许形成连贯的枕头而不会碎裂。基于这些约束条件，枕瓣形成的条件是：黏度在104.5 ~ 106.8 Pa·s之间，点源的挤压速率在2.4 ~ 3.1 × 103 m3/s之间，线源的挤压速率在2.4 ~ 3.1 × 10−3 m2/s之间。这样的黏度要求岩浆的含水量超过1.4质量%，这表明最初在陆地上挤压并在水饱和条件下放置的火成岩是由水焊接而成的。

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引用次数: 0

Corrigendum to “Viscosity of bubbly magmas from torsional experiments on pumice” [Journal of Volcanology and Geothermal Research 461 (2025) 108297] “浮石扭转实验中气泡岩浆的粘度”的勘误表[火山学与地热研究杂志461 (2025)108297]

IF 2.3 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Volcanology and Geothermal Research

Pub Date : 2025-12-01 Epub Date: 2025-10-22 DOI: 10.1016/j.jvolgeores.2025.108475

Gaetano Ferrante , Helge Gonnermann , Céline Fliedner , Thomas Giachetti , Amy G. Ryan

引用次数: 0

Vent-specific unrest at Pavlof Volcano, Alaska: Insights from multidisciplinary data 阿拉斯加帕夫洛夫火山的特定火山喷发：来自多学科数据的见解

IF 2.3 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Volcanology and Geothermal Research

Pub Date : 2025-12-01 Epub Date: 2025-10-11 DOI: 10.1016/j.jvolgeores.2025.108465

Darren Tan , David Fee , Pavel Izbekov , Taryn Lopez , Társilo Girona , Vanesa Burgos , Stephen McNutt , Matthew Haney , Valerie Wasser , Jessica Larsen , Ronni Grapenthin , Mario Angarita , Pablo Saunders-Shultz , Tara Shreve , Jamshid Moshrefzadeh

Pavlof Volcano, a frequently active volcano in the Aleutian arc, has erupted six times between 2007 and 2022. Many Pavlof Volcano eruptions lack detectable precursory seismicity or ground deformation, making them challenging to forecast. Since 2007, these eruptions have ranged from Strombolian to Subplinian (VEI 2–3), with their characteristics seemingly related to their active vent location. Summit vent eruptions tend to be abrupt and explosive, while southeast flank vent eruptions tend to be more effusive and longer-lived. To better understand Pavlof Volcano’s plumbing system and improve eruption forecasts, we integrate geophysical, petrologic, and satellite-based thermal infrared and gas data to conduct a multidisciplinary data synthesis for eruptions between 2007 and 2022. Notably, a recently developed volcano seismicity detection model reveals unique pre- and syn-eruptive seismic tremor regimes associated with each vent system. The summit vent eruptions show greater tremor diversity and resurgent eruptive behavior, whereas the southeast flank vent eruptions show a steady tremor transition over a single eruptive phase. We use local infrasound data and air-to-ground coupled waves to build explosion catalogs, revealing gas-rich explosions during the 2021–2022 eruption from the summit vent, which was previously thought to be inactive during that eruption. Whole-rock composition and ash analyses indicate a near-uniform basaltic andesite composition spanning multiple eruptions, and a consistent anomalous presence of altered olivines in erupted material. We use these findings to propose a new conceptual model for Pavlof Volcano’s plumbing system: a shallow T-junction outlet controlling seismic tremor diversity and the partitioning of gas-charged magma; and an elongated, heated conduit transporting magma from depth and storing partly molten, residual magma between eruptions. We suggest that magma ascent rate and vent sealing modulate eruption style at Pavlof Volcano, where the T-junction directs rapidly ascending, gas-rich magma to the summit vent, and diverts slower rising, gas-poor magma towards the southeast flank vent.

巴甫洛夫火山是阿留申岛弧上一座经常活跃的火山，在2007年至2022年间爆发了六次。许多巴甫洛夫火山爆发缺乏可探测到的前兆地震活动或地面变形，这使得预测具有挑战性。自2007年以来，这些喷发从斯特隆堡喷发到subplian喷发（VEI 2-3），其特征似乎与它们的活跃喷口位置有关。峰顶的喷口喷发往往是突然的和爆炸性的，而东南侧的喷口喷发往往更热情，更持久。为了更好地了解巴甫洛夫火山的管道系统并改进喷发预测，我们整合了地球物理、岩石学和卫星热红外和气体数据，对2007年至2022年的喷发进行了多学科数据综合。值得注意的是，最近开发的火山地震活动性检测模型揭示了与每个喷口系统相关的独特的喷发前和喷发时地震震颤状态。峰顶喷口喷发表现出更大的震颤多样性和再次爆发行为，而东南侧喷口喷发在单个喷发阶段表现出稳定的震颤过渡。我们使用当地的次声数据和空对地耦合波来建立爆炸目录，揭示了2021-2022年山顶喷口喷发期间富含气体的爆炸，此前人们认为该喷口在那次喷发期间不活跃。整个岩石组成和火山灰分析表明，在多次喷发中，玄武岩安山岩组成几乎一致，并且在喷发物质中一致存在异常的蚀变橄榄石。我们利用这些发现提出了一个新的Pavlof火山管道系统的概念模型：一个控制地震震动多样性和充气岩浆分配的浅t型结出口；还有一条细长的加热管道，从深处输送岩浆，并在两次喷发之间储存部分熔融的残余岩浆。岩浆上升速率和火山口封闭性调节了Pavlof火山的喷发方式，其中t型接头将快速上升的富气岩浆引导至山顶喷口，并将缓慢上升的贫气岩浆引导至东南翼喷口。

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引用次数: 0

First year of magnetotelluric observations at Villarrica volcano, Southern Andes 南安第斯山脉维拉里卡火山大地电磁观测的第一年

IF 2.3 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Volcanology and Geothermal Research

Pub Date : 2025-12-01 Epub Date: 2025-10-15 DOI: 10.1016/j.jvolgeores.2025.108474

Daniel Díaz , Maximiliano Pavez , Álvaro Amigo

Villarrica volcano is located in the Southern Andes, one of the world's most productive volcanic arcs of the last decades and stands as the most active volcano in South America, in terms of the number of registered eruptive episodes. Besides its large eruptive record, Villarrica has other particularities, such as being currently an open conduit volcano providing a pathway through which volatiles and magma rise to the surface forming a persistent lava lake at its crater.

These features make Villarrica one of the most relevant volcanoes to study along the Andes, and efforts to characterize its internal magmatic structure have arisen during recent years. Along with geochemical and geophysical measurements normally used to image the magmatic system of this volcano, the use of monitoring methods to analyze different changes in time are needed to improve the understanding of active volcanic systems such this one.

Through a research project to test the capabilities of magnetotellurics as a volcano monitoring tool, a first permanent broad-band magnetotelluric station was installed at Villarrica volcano during January 2023, and has been measuring since then. Even considering the limitations of a single station experiment, interesting changes in magnetotelluric parameters measured during 2023 and beginning of 2024 have been estimated, and compared to other geophysical and geological parameters measured during this time, aiming to improve our monitoring capabilities and provide new insights into the magmatic processes at one of the most active volcanoes in the Andes.

比利亚里卡火山位于南安第斯山脉，是过去几十年来世界上最具生产力的火山弧之一，也是南美洲最活跃的火山，就喷发次数而言。除了大规模的喷发记录外，维拉里卡火山还有其他的特点，比如它目前是一个开放的管道火山，提供了一个通道，通过这个通道，挥发物和岩浆上升到表面，在火山口形成了一个持久的熔岩湖。这些特征使维拉里卡火山成为沿安第斯山脉研究最相关的火山之一，近年来，人们开始努力描绘其内部岩浆结构。除了通常用于该火山岩浆系统成像的地球化学和地球物理测量外，还需要使用监测方法来分析不同的时间变化，以提高对此类活火山系统的了解。通过一个测试大地电磁作为火山监测工具的能力的研究项目，2023年1月在比利亚里卡火山安装了第一个永久性宽带大地电磁站，并从那时起一直在测量。即使考虑到单站实验的局限性，也估计了2023年至2024年初测量的大地电磁参数的有趣变化，并与此期间测量的其他地球物理和地质参数进行了比较，旨在提高我们的监测能力，并为安第斯山脉最活跃的火山之一的岩浆过程提供新的见解。

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