Journal of Volcanology and Geothermal Research最新文献

{"title":"Spatiotemporal characteristics of hydrothermal volatiles from the Tengchong volcanic field in the southeastern Tibetan Plateau: A probable constraint on the genesis of intraplate volcanism","authors":"Yingchun Wang ,&nbsp;Xiaocheng Zhou ,&nbsp;Jiao Tian ,&nbsp;Haoxin Jia ,&nbsp;Xiaoyi Zhu ,&nbsp;Jiang Li ,&nbsp;Miao He ,&nbsp;Zhaojun Zeng ,&nbsp;Yucong Yan ,&nbsp;Bingyu Yao ,&nbsp;Yuwen Wang ,&nbsp;Gaoyuan Xing ,&nbsp;Shihan Cui ,&nbsp;Liwu Li ,&nbsp;Zhongping Li ,&nbsp;Chunhui Cao ,&nbsp;Lantian Xing","doi":"10.1016/j.jvolgeores.2024.108237","DOIUrl":"10.1016/j.jvolgeores.2024.108237","url":null,"abstract":"<div><div>Determining parent magmatic sources of active and dormant volcanoes is crucial for understanding their formation and geodynamic processes. The Tengchong volcanic field (TCV), an intraplate volcanic group located in the southeastern part of the Qinghai–Tibet Plateau, is linked to mantle disturbances through the eastward subduction of the Indian plate. By comprehensive analysis helium and carbon isotopes in hot springs in the TCV, this study revealed that volatile degassing within the TCV predominantly originated from the mantle. Volatile degassing history, coupled with a helium magma aging model, corroborated that the helium of the parent magma was similar to that found in oceanic island basalts, probable sourced from stagnant oceanic slab dehydration above the mantle transition zone, firstly providing compelling geochemical evidence for the upwelling of profound mantle materials. This research not only elucidates the enigmatic geothermal behaviors of intraplate volcanoes but also enhances our understanding of the tectonic dynamics of SE Tibetan Plateau.</div></div>","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"457 ","pages":"Article 108237"},"PeriodicalIF":2.4,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142698191","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 ghost plume phenomenon and its impact on zenith-facing remote sensing measurements of volcanic SO2 emission rates","authors":"D. Skye Kushner ,&nbsp;Taryn Lopez ,&nbsp;Christoph Kern ,&nbsp;Santiago Arellano ,&nbsp;Nemesio M. Pérez ,&nbsp;José Barrancos","doi":"10.1016/j.jvolgeores.2024.108217","DOIUrl":"10.1016/j.jvolgeores.2024.108217","url":null,"abstract":"<div><div>A large source of error in SO₂ emission rates derived from mobile Differential Optical Absorption Spectroscopy (DOAS) of volcanic gas plumes is the uncertainty in atmospheric light paths between the sun and the instrument, particularly under non-ideal atmospheric conditions, such as the presence of low clouds. DOAS instruments measure the SO₂ column density along the effective light path, so changes to that pathway directly affect the measured SO₂ signal. Due to complex radiative transfer mechanisms when a cloud is between the DOAS viewing position and a volcanic plume, measured plumes can appear spatially offset from their true location, a phenomenon informally referred to as “ghost plumes.” In addition to the appearance of ghost plumes, DOAS measurements recorded in non-ideal conditions have poorly characterized errors and are often discarded, limiting the data available to characterize volcanic degassing. In this study we simulate the radiative transfer associated with zenith-facing mobile DOAS traverses using the McArtim radiative transfer model for scenarios when there is a cloud layer between the instrument and the volcanic plume. In total, 217 permutations of atmospheric optical conditions are considered with varying cloud opacities (AOD = 0, 1, 2, 4, 8, 20), plume opacities (AOD = 0, 1, 2, 4, 8), solar zenith angles (SZA = 1°, 30°, 60°), and cloud thicknesses (200, 400, 800 m). We first develop objective criteria for selecting SO₂ baseline absorption levels and plume spatial extents. The simulated plume traverses are then integrated to obtain the SO₂ cross-sectional burdens which, after multiplication with the wind speed, yield SO₂ emission rates. We find large modification in the shape of the modeled cross-sectional burdens even under translucent (low AOD) cloud conditions in our modeled scenarios. Despite modification of the plume shape, the presence of a low cloud layer is typically not a large source of error in the SO₂ cross-sectional burden or emission rate obtained from zenith-facing DOAS traverses. We find that all measured cross-sectional burdens simulated using an aerosol-free plume in the above conditions and SZA ≤ 30° are within ±25% of the true value.</div></div>","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"457 ","pages":"Article 108217"},"PeriodicalIF":2.4,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142720542","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":"Surface deformation caused by the unrest during 2002–2006 of the Changbaishan volcano in China","authors":"Hongbao Liang ,&nbsp;Dan Xu ,&nbsp;Jingwei Li","doi":"10.1016/j.jvolgeores.2024.108234","DOIUrl":"10.1016/j.jvolgeores.2024.108234","url":null,"abstract":"<div><div>The Changbaishan volcano is recognized as one of China's most potentially dangerous active volcanoes. In response to the unrest event of 2002, GPS technology was utilized to monitor the surface deformation it induced. However, the understanding of the volcano's dynamics and the intricacies of GPS data at the time were limited, which affected the quality of the conclusions. For example, the commencement of GPS observations followed the escalation of seismic activities, leading to the loss of some deformation information. Moreover, observational noise in the GPS coordinate sequences introduced oscillations in the evolution of deformation characteristics. To overcome these limitations, we have developed an advanced GPS data processing methodology. This includes the establishment of a meticulous three-tier control network, the employment of high-precision geophysical models in GAMIT/GLOBK software, the creation of a volcanic regional reference frame, and the formulation of a sophisticated motion model for monitoring stations. With these approaches, we have captured the maximum surface deformation caused by the unrest and have re-evaluated the volume change (25.95× 10⁶ m³/year) of the magma chamber based on Mogi model, yielding results that significantly surpass the mean of previous estimates of 8.58 × 10⁶ m³/year and enhancing our understanding of the magma chamber's dimensions. Additionally, the surface deformation following the unrest displayed a pattern of continuous decay, which is in contrast to the seismic activity that initially rose and then declined, peaking notably after the surface deformation's peak. Considering the geological context of the volcano's formation, we have also provided an extensive dataset of GPS velocity fields. We have preliminarily discussed the possible relationship between the subduction of the Pacific Plate and the unrest in 2002, as well as the recent low-level unrest in 2021, acknowledging that this hypothesis requires further confirmation through stress modeling related to the disturbances. The deformation data resulting from the unrest, as well as the background deformation caused by plate subduction presented in this study, provide essential data constraints for the construction of subsequent stress models.</div></div>","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"457 ","pages":"Article 108234"},"PeriodicalIF":2.4,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142698259","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":"Evolution of eruption rate between two caldera-forming eruptions in the Jemez Mountains volcanic field, New Mexico, USA","authors":"Nicholas F. Meszaros ,&nbsp;Matthew J. Zimmerer ,&nbsp;James E. Gardner","doi":"10.1016/j.jvolgeores.2024.108216","DOIUrl":"10.1016/j.jvolgeores.2024.108216","url":null,"abstract":"<div><div>Rhyolites that erupted between the Otowi and Tshirege members of the Bandelier Tuff, known as the Valle Toledo Member, were investigated in the Jemez Mountains volcanic field to infer changes in eruptive rate and flux between two caldera-forming eruptions. Our analysis combines high-precision ⁴⁰Ar/³⁹Ar single-crystal laser-fusion dating of sanidine, matrix glass compositions and mineralogy of pumice, depositional textures, and volumetric estimates of erupted rhyolites to present a revised Valle Toledo Member eruptive chronology that integrates our observations with those of previous studies. With the improved temporal resolution of our high-precision eruption ages (median 2σ uncertainty of ±2.9 ka), the updated Valle Toledo Member eruption chronology consists of at least 42 temporally or mineralogically distinct eruptions that we group into four periods of time based on eruption rate. Within the first 8.1 ± 5.1 kyr (∼1605–1597 ka) that followed the Otowi caldera-forming eruption at 1605.4 ± 2.3 ka, six eruptions are recognized. This suggests an average recurrence interval on the order of 1.4 ± 0.9 kyr. Twenty-seven eruptions occurred during the next 194.4 ± 5.1 kyr (from ∼1597–1403 ka) and the average recurrence interval increased to 7.2 ± 0.2 kyr. Following this second period of slower eruption rate, a previously unrecognized eruption hiatus of up to 162.4 ± 3.1 kyr occurred from 1402.9 ± 2.3 ka to 1240.5 ± 2.1 ka. Resumption of volcanic activity is characterized by a series of at least nine volcanic eruptions during the next 8.6 ± 2.5 kyr, culminating in the eruption of the 400 km³ Tshirege Member of the Bandelier Tuff and formation of Valles caldera at 1231.9 ± 1.3 ka. This last phase of pre-caldera activity has the shortest observed average recurrence interval (1.0 ± 0.3 kyr) and greatest eruptive flux (≥ 0.4 ± 0.2 km³/kyr) that occurred between the two caldera-forming eruptions. We interpret the shifts in eruption rate and flux following the 162.4 ± 3.1 kyr eruption hiatus, in addition to mineralogical changes present in post-hiatus rhyolites, as indicators that the Bandelier system was trending towards another major eruption. The magmatic system may have grown gradually throughout the ca. 162 kyr period of volcanic repose; however, the heightened eruption rate in the ca. 10 kyr before caldera collapse is consistent with relatively rapid growth of the magmatic system before the Tshirege event as previously proposed by other studies. Furthermore, the new dataset is consistent with prior geochronology studies of the region that show the four largest explosive eruptions in the Jemez field were all proceeded by very slow eruptive rates or hiatuses. This demonstrates that sequences of heightened volcanic activity can initiate on rapid geological timescales from states of volcanic quiescence in the Bandelier system.</div></div>","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"457 ","pages":"Article 108216"},"PeriodicalIF":2.4,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142698257","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":"Feeding system beneath active volcanoes in central part of Iturup Island (Kuril Arc) inferred from local earthquake tomography","authors":"Ivan Koulakov ,&nbsp;Evgeny Ilyich Gordeev ,&nbsp;Ilyas Abkadyrov ,&nbsp;Olga Bergal-Kuvikas ,&nbsp;Danila Chebrov","doi":"10.1016/j.jvolgeores.2024.108233","DOIUrl":"10.1016/j.jvolgeores.2024.108233","url":null,"abstract":"<div><div>Iturup is the largest island of the Kuril Arc with more than 20 Holocene volcanoes of which 9 considered active. Here we investigate the central part of the island where we deployed in 2022–2023 a portable network of 12 seismic stations. The data of this network together with several permanent stations in surrounding islands were used to identify almost 300 events and to perform seismic tomography based on the picked arrival times of the P and S seismic waves. A challenging problem was that most of the events were located outside the network, and we performed careful analysis to examine the actual capacity of inversion with such data to recover seismic velocity structures below the network. In the resulting model, we found a dominating high-velocity anomaly below the central part of the study area, which is bounded by zones of low velocities and high Vp/Vs ratio collocated with two active volcano complexes (Chirip to the north and Ivan Grozny to the south). Below the third volcano, Baransky, we observe a change of the Vp/Vs ratio from high at large depths to low at shallow depth, indicating the process of degassing, which is supported by strong fumarolic activity and hydrothermal manifestations around this volcano. At depths of more than 20 km, the feeding paths from Baransky and Ivan Grozny volcanoes seem to be connected in one anomaly representing a common magma source below the center of the island. This seems to be a common feature observed below several volcanic islands, such as Tenerife and El Hierro, where the high-velocity rigid core in a central part is surrounded by low-velocity flows associated with recent volcanic manifestations.</div></div>","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"456 ","pages":"Article 108233"},"PeriodicalIF":2.4,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142652527","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 influence of FeTi oxide microlites on bubble nucleation in rhyolitic melts","authors":"Wade L. Aubin ,&nbsp;James E. Gardner","doi":"10.1016/j.jvolgeores.2024.108218","DOIUrl":"10.1016/j.jvolgeores.2024.108218","url":null,"abstract":"<div><div>We conducted a set of high-temperature decompression experiments to constrain the mechanisms of heterogeneous bubble nucleation in high-silica rhyolitic melt that contained 4.6–4.8 wt% H₂O. The melt was seeded with two different size fractions of magnetite crystals: 1–2 μm crystals and large crystals of 32–135 μm (long axis). The number density of bubbles (BND) that nucleated on the small crystals was found to increase from 10^6.5 to 10^8.7 cm⁻³ as H₂O increasingly supersaturated (ΔP) in the melt from 3 to 23 MPa. At ΔP &gt;23 MPs, however, the number of bubbles nucleated equals the number of small magnetite and no more nucleated with increased ΔP. At the same conditions, the number of bubbles that nucleated on the large crystals increases, from &lt;1 bubble per crystal at ΔP = 3 MPa to 14 ± 4 bubbles per crystal at 58 MPa. We thus find that ΔP has a significant influence on the mechanisms of heterogenous nucleation, but the observed increases in BND are much greater than would be predicted solely from the increase in ΔP. The discrepancy can be reconciled if there are different sites on the crystals that become activated at greater ΔP, leading to greater numbers of bubbles nucleating. The cumulative BND nucleated on small crystals, however, is capped by the number of crystals present. The BND values generated at ΔP &gt;23 MPa in our experiments overlap with those found in ∼80 % of naturally occurring pumice. Assuming our experiments are representative of natural pumice, this suggests that explosively erupted magmas either become significantly volatile supersaturated before heterogeneously nucleating bubbles, or that the number of nucleation sites in natural magmas greatly exceed 10⁹ cm⁻³.</div></div>","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"456 ","pages":"Article 108218"},"PeriodicalIF":2.4,"publicationDate":"2024-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142652528","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 dynamic of magmatic system and volcano hazard implications of the Damavand volcano (N. Iran) inferred from the textural data","authors":"Amir Eskandari ,&nbsp;Sadraddin Amini ,&nbsp;Behnam Sadeghi","doi":"10.1016/j.jvolgeores.2024.108220","DOIUrl":"10.1016/j.jvolgeores.2024.108220","url":null,"abstract":"<div><div>The Damavand stratovolcano (N Iran) consists mainly of lavas with trachyandesite-trachyte composition, and subordinate pyroclastic deposits. The intensity of explosive eruptions and the volume of pyroclastic deposits have increased over time, which may be related to increasing viscosity due to the development of crystal-rich magmas. This research integrates microanalytical and quantitative textural measurements to understand the textural evolutions from the old to the young lavas and their relationships with the physical processes occurred in the plumbing system. Age-constrained samples from the lavas were analyzed using crystal size distribution (CSD), the newly proposed multifractal analysis, including the Number-Length of crystals (N-LoC) and the Number-Area of crystals (N-AoC), along with mineral chemistry. Three to five populations of feldspars can be identified, which have undergone evolution and coarsening over time. We propose a textural development sequence established at mid to shallow crustal levels, involving several physicochemical processes, such as cycles of polybaric differentiation and episodic magma recharge into the crystal-rich magma chambers. This, in turn, caused disaggregation of crystal mushes and textural coarsening due to crystal aggregation and temperature cycling. The increasing population of microphenocrysts in younger lavas may be linked to pulsating groundmass crystallization resulting from degassing at a newly formed shallow chamber (0.5–1 kbar) beneath the young cone. The final stages of crystallization occurred during multi-step decompression in the conduits. The comparison of age data from lava samples and their stratigraphic positions suggests that triggering groundmass crystallization might have caused shifts in eruptive behavior.</div></div>","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"456 ","pages":"Article 108220"},"PeriodicalIF":2.4,"publicationDate":"2024-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142652529","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":"Experimental constraints on the behaviour of sulphur in the 2021 Cumbre Vieja (La Palma) basanite","authors":"Diletta Frascerra ,&nbsp;Bruno Scaillet ,&nbsp;Joan Andújar ,&nbsp;Clive Oppenheimer ,&nbsp;Stéphane Scaillet ,&nbsp;Joan Martí ,&nbsp;Ramón Casillas ,&nbsp;Carmen López","doi":"10.1016/j.jvolgeores.2024.108219","DOIUrl":"10.1016/j.jvolgeores.2024.108219","url":null,"abstract":"<div><div>We performed experiments to constrain the effects of sulphur and oxygen fugacities on magma chamber and outgassing conditions of the La Palma 2021 eruption. Based on a series of controlled experiments on basanitic products carried out at 1040 °C and 200 MPa, we show that sulphur addition affects the stabilities of amphibole and olivine, in particular at high <em>f</em>O₂ and elevated S contents which together inhibit amphibole crystallization. We also show that the overriding control on S systematics is oxygen fugacity, with melts capable of dissolving from 1000 up to 8000 ppm S, depending on <em>f</em>O₂. Increasing the bulk S content increases the S content of the silicate melt up to ∼2000 ppm for <em>f</em>O₂ &lt; NNO + 2, and 7000–8000 ppm at higher <em>f</em>O₂. Further increase in dissolved S is prevented by the buffering effects of either sulphide at low <em>f</em>O₂ or anhydrite at high <em>f</em>O₂. Modelling shows that the observed CO₂/SO₂ and H₂O/SO₂ ratios of volcanic gas emissions during the eruption imply a pre-existing &gt;5 wt% exsolved fluid in the reservoir, with <em>f</em>S₂ at ∼0.1 MPa at <em>f</em>O₂ above NNO. Our work confirms that basaltic magmas may coexist with a significant amount of excess fluid which in turn holds an important part of the sulphur budget emitted to the atmosphere.</div></div>","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"456 ","pages":"Article 108219"},"PeriodicalIF":2.4,"publicationDate":"2024-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142652530","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":"Conduit armouring preceding explosive activity at an andesitic stratovolcano, an example from Taranaki Mounga, New Zealand","authors":"Henry Hoult ,&nbsp;Ben M. Kennedy ,&nbsp;Alexander R.L. Nichols ,&nbsp;Shane Cronin ,&nbsp;Leighton Watson","doi":"10.1016/j.jvolgeores.2024.108214","DOIUrl":"10.1016/j.jvolgeores.2024.108214","url":null,"abstract":"<div><div>The strength and permeability of volcanic conduits can directly influence eruption dynamics via moderating the outgassing of ascending magma and the density of eruption plumes. Lithic clasts in pyroclastic ejecta can be used to understand the dynamic evolution of conduit walls because they are incorporated into the ascending melt-gas-particle mixture during volcanic eruptions. We examine the 1655 CE Burrell eruption of Taranaki Mounga, which transitioned from effusive activity to an explosive sub-Plinian phase and ended in unsteady columns. This episode was followed by a series of effusive eruptions of lower explosivity. Using textural analysis and physical properties, we distinguish five dominant lithic clast types within Burrell deposits that represent different regions of the shallow conduit and vent. Lithic types 1–3 represent juvenile (‘intrusive cognate’) and older (‘intrusive accessory’) conduit-filling plug materials. Lithic type 4 represents juvenile (‘extrusive cognate’) vent-filling lava dome extruded at the eruption onset, while Type 5 lithics (‘extrusive cognate’) represent sintered/compacted cognate material from the shallow vent accumulated during transitions in eruptive style. Crystalline andesite lithics (type 1) show a microlite-dominated groundmass. Hydrothermally altered andesite lithics (type 2) show breakdown of phenocrysts and increased seismic velocity relative to type 1 lithics. Brecciated andesite lithics (type 3) comprise fractured and sintered clasts of crystalline andesite. Glassy andesite lithics (type 4) show sub-rounded vesicles and glass-hosted microlites. Banded vitrophyre lithics (type 5) show bands of varying vesicularity, crystallinity and clast load. Physical property data reveals porosity, fracturing, sintering and alteration extent dictate dynamic changes in conduit permeability and potentially strength. Our results show how, during the explosive phase of the Burrell eruption, the conduit was lined with juvenile and remnant shallow plug material that was variably fractured, sintered and altered before being eroded and ejected. Comparison with previous work on Taranaki and dome-plug material from around the world shows how fracturing and sintering of conduit walls, combined with lining with dense juvenile material, cause overall permeability reduction and strengthening of the conduit. This inhibits outgassing and preserves conduit structure, facilitating the transition to explosive activity and the establishment of a stable eruption column.</div></div>","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"455 ","pages":"Article 108214"},"PeriodicalIF":2.4,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142561203","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":"Volcanic tremor associated with successive gas emission activity at a boiling pool: Analyses of seismic array and visible image data recorded at Iwo-Yama in Kirishima Volcanic complex, Japan","authors":"Masato Hata ,&nbsp;Takeshi Nishimura ,&nbsp;Takeshi Matsushima ,&nbsp;Tomofumi Kozono ,&nbsp;Tsutomu Nagatsuma ,&nbsp;Ken T. Murata ,&nbsp;Kazutaka Kikuta ,&nbsp;Dan Muramatsu ,&nbsp;Hisashi Nakahara","doi":"10.1016/j.jvolgeores.2024.108212","DOIUrl":"10.1016/j.jvolgeores.2024.108212","url":null,"abstract":"<div><div>Volcanic tremors are often observed during volcanic activity and volcanic eruptions, and their generation processes provide clues for understanding volcanic fluid activity underground and eruption dynamics. However, tremors are characterized by continuous oscillations that mask P- and S-waves; hence few studies have precisely located the source, which is the most fundamental information for understanding the generation mechanism. In this study, we focus on volcanic tremors excited by continuous gas emissions occurring at a vent called Y2a in Iwo-Yama, the Kirishima Volcanic Complex, Japan, to clarify the source process of the tremor as well as gas emission activity. We simultaneously observed the volcanic tremor by deploying a small aperture array consisting of six seismometers and the gas emission activity by using a newly developed visual IoT system that can be operated without commercial electricity. MUSIC analysis locates the tremor at depths ranging from the ground surface to approximately 200 m beneath the Y2a and Y2b vents, which are approximately 30 m apart, for approximately four months from November 2021 to February 2022. The source locations of the tremors in the 2 Hz (1.2–2.6 Hz), 4 Hz (3–4 Hz), and 5 Hz (4–5.5 Hz) ranges show some differences and changes with time. The source location tends to become deeper when the 2 Hz amplitude is large. The infrasound generated by gas emission activity is dominant in the tremor signals, which are recognized in the wave propagation velocity with an acoustic velocity of 330 m/s when the 2 Hz amplitude is small. The visual IoT system succeeded in detecting long-term changes in the gas emission activity, and we found that the 2 Hz amplitude of tremor was well correlated with the amount of hot water in the boiling pool of Y2a, which was controlled by precipitation and evaporation during non-rainy days. From these observations, we infer that the volcanic tremor is generated by resonance of volcanic gas and hot water in a crack-like structure beneath Y2a. The resonance was triggered by the counterforces of the gas emissions in the boiling pool, and the infrasound was dominant during periods of hot water depletion in the boiling pool. Temporal changes in the source depths may be caused by changes in the fluid properties, configuration of the resonator and/or the strengths of the underground sources and infrasound. Our simultaneous observations of seismic array and visual IoT system clarify that even the continuous gas emission activity that looks stable is controlled by external sources such as precipitation.</div></div>","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"455 ","pages":"Article 108212"},"PeriodicalIF":2.4,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142553131","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}