Journal of Volcanology and Geothermal Research最新文献

{"title":"Source analysis of low frequency seismicity at Mt. Vesuvius by a hybrid moment tensor inversion","authors":"R. Manzo ,&nbsp;S. Cesca ,&nbsp;D. Galluzzo ,&nbsp;M. La Rocca ,&nbsp;M. Picozzi ,&nbsp;R. Di Maio","doi":"10.1016/j.jvolgeores.2024.108173","DOIUrl":"10.1016/j.jvolgeores.2024.108173","url":null,"abstract":"<div><p>Seismicity at Mt. Vesuvius has been relatively weak in the last decades. While the occurrence of shallow volcano-tectonic (VT) events at Mt. Vesuvius is well known, the occurrence of deeper low frequency events (LF) was only recently recognized. Previous source studies only targeted VT events, which were found to have quite heterogeneous focal mechanisms. In this paper, we perform for the first time the source inversion of LF seismicity at Mt. Vesuvius, analysing 27 LF events recorded from 2012 to 2021 with the aim to investigate their source processes. Given the challenges of analysing weak LF earthquakes, we implement a specific moment tensor (MT) inversion approach that combines the fit of displacement seismograms in the time domain and amplitude spectra in the frequency domain. The inversion is simultaneously performed for the source depth and moment tensor components in the 2–7 and 2–5 Hz frequency band, assuming either a full or deviatoric MT representation. Source parameter uncertainties are estimated by using a Bayesian bootstrapping scheme. Our results confirm a larger depth of LF events compared to VTs and show a strong heterogeneity of the LF seismic sources, which present various rupture types, different orientations and heterogeneous, whilst poorly resolved, non-double-couple components. The MT variability is qualitatively confirmed by significant differences among the recorded waveforms. The heterogeneity of both VT and LF source processes is attributed to complex source processes in a highly fractured seismogenic volume submitted to a heterogeneous stress field.</p></div>","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"454 ","pages":"Article 108173"},"PeriodicalIF":2.4,"publicationDate":"2024-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142048009","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":"Development of permeable networks by viscous-brittle deformation in a shallow rhyolite intrusion. Part 1: Field evidence","authors":"Taylor Witcher ,&nbsp;Steffi Burchardt ,&nbsp;Tobias Mattsson ,&nbsp;Michael J. Heap ,&nbsp;William McCarthy","doi":"10.1016/j.jvolgeores.2024.108166","DOIUrl":"10.1016/j.jvolgeores.2024.108166","url":null,"abstract":"<div><p>Efficient outgassing of shallow magma bodies reduces the risk of explosive eruption. Silica-rich magmas are too viscous for exsolved gas bubbles to escape the system through buoyant forces alone, and so volatile overpressure is often released through deformation-related processes. Here we present a case study on magma emplacement-related deformation in a shallow (∼500 m depth) rhyolite intrusion (the Sandfell laccolith, Eastern Iceland) to investigate the establishment of degassing (volatile exsolution) and outgassing (gas escape) networks in silicic sub-volcanic intrusions. We observe viscous and brittle deformation features: from vesiculated flow bands that organized into ‘pore channels’ in the ductile regime, to uniform bands of tensile fractures (‘fracture bands’) that grade into breccia and gouge in the brittle regime. Through field mapping, structural analysis, and anisotropy of magnetic susceptibility (AMS) measurements, we show that areas with higher degrees of brittle deformation are proximal to abruptly changing AMS fabrics, and flow band orientations and point to laccolith-wide strain partitioning in the magma. We associate the changes in flow fabrics and the intensity of brittle deformation to the transition from dominantly horizontally flowing magma during initial sill-stacking to up to the NE magma flow linked to the propagation of a trap-door fault from the N to the SE. The establishment of intrusion-scale brittle permeable networks linked to changes in strain partitioning that facilitated magma flow during different stages of laccolith growth would have profoundly assisted the outgassing of the entire laccolith. Magmatic fracturing captures viscous and brittle processes working in tandem as an efficient outgassing mechanism, and should be considered in sub-volcanic intrusions elsewhere.</p></div>","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"454 ","pages":"Article 108166"},"PeriodicalIF":2.4,"publicationDate":"2024-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0377027324001586/pdfft?md5=41adc5299e3afef48b103515b8a39e99&pid=1-s2.0-S0377027324001586-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142040847","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":"Magma storage conditions beneath a peralkaline caldera in the Main Ethiopian Rift","authors":"David J. Colby ,&nbsp;David M. Pyle ,&nbsp;Karen Fontijn ,&nbsp;Tamsin A. Mather ,&nbsp;Sebastien Nomade ,&nbsp;Abate A. Melaku ,&nbsp;Million A. Mengesha ,&nbsp;Gezahegn Yirgu","doi":"10.1016/j.jvolgeores.2024.108165","DOIUrl":"10.1016/j.jvolgeores.2024.108165","url":null,"abstract":"<div><p>The numerous volcanic centres in the Main Ethiopian Rift (MER) present significant but poorly understood hazards to local populations. The MER is also an important site to gain insights into tectonic processes as it captures the transition from continental rifting (to the south) to incipient seafloor spreading (to the north). Peralkaline magmas account for around 90% of the volcanic products found in the MER. Determining the conditions under which these magmas evolve is critical to understanding rift-related volcanism and its associated hazards. Corbetti Caldera has an extensive record of large-scale, predominantly aphyric, peralkaline rhyolite eruptions. However, little is known about the mafic magmas from which these highly differentiated melts have evolved. Here we present data from the only basaltic deposit found within the caldera, coupled with whole rock, glass and mineral analysis of the peralkaline products, to investigate magma storage conditions at Corbetti. We demonstrate that magma mixing played a role in the evolution of the basaltic magmas and use RhyoliteMELTS modelling to show Corbetti's peralkaline magmas likely evolved at pressures between 100 and 250 MPa, from a magma with an initial water content of 0.5–1 wt%, at or below the QFM buffer. Mineral hygrometry on the sparse crystal populations corroborates the RhyoliteMELTS modelling, suggesting that the basaltic magma had 0.1–1.2 ± 0.32 wt% H₂O, and the peralkaline magmas an average of ∼5.5 ± 1.25 wt% H₂O. These results also match melt inclusion data for Corbetti and other peralkaline systems. We also provide new ⁴⁰Ar/³⁹Ar ages for two eruptions, a pre-caldera rhyolitic lava flow (206.7 ± 0.9 ka) and a post-caldera peralkaline ignimbrite (160 ± 0.8 ka). These results add to our understanding of the history of Corbetti and the storage conditions of peralkaline magmas within a continental rift setting and highlight the hydrous nature of Corbetti's magmas and the role that H₂O plays during explosive eruptions.</p></div>","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"455 ","pages":"Article 108165"},"PeriodicalIF":2.4,"publicationDate":"2024-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0377027324001574/pdfft?md5=05a327e685523dc8a987caf25b34e395&pid=1-s2.0-S0377027324001574-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142158460","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":"Constraining proximal grainsize distribution of tephra from paroxysmal eruptions at Etna volcano","authors":"Francesco Amadio ,&nbsp;Laura Pioli ,&nbsp;Simona Scollo","doi":"10.1016/j.jvolgeores.2024.108164","DOIUrl":"10.1016/j.jvolgeores.2024.108164","url":null,"abstract":"<div><p>This study examines proximal deposits associated with 17 lava fountains occurring at the South-East Crater between 16/02 and 1/04, 2021. This eruptive crisis gave rise to some of the most intense eruptions at Etna in the last decade. We studied products deposited from 1 to 3.2 km to the south of the vent. Tephra was preserved within and at the top of the snowpack and layers were correlated based on eruption chronology, remote sensing data on the plume dispersal, and precipitation chronology. The grainsize distribution of these proximal and ultra-proximal deposits is multimodal, with Mdɸ ranging from −2.79 and − 1.84, and σɸ 1.34 and 1.80. Refined data (50% of the main population range between Mdɸ −2.63 and − 1.63ɸ, and σɸ 1.01 and 1.41) were used in a comparative study with existing datasets for selected eruptions to assess the representativity of our data and define a Mdɸ/distance correlation along the dispersal axis. Finally, the contribution of proximal data on the total grainsize distribution suggest that they significantly affect the median grainsize values. A complete sampling could decrease it by up to 2 phi units when compared to distribution based only on medial to distal sampling. Results from this study reinforce the importance of collecting samples in proximal areas.</p></div>","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"454 ","pages":"Article 108164"},"PeriodicalIF":2.4,"publicationDate":"2024-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0377027324001562/pdfft?md5=aa721653fd9dad487734e725198a8cd9&pid=1-s2.0-S0377027324001562-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142096557","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":"Shallow crustal structure of eastern trans-Mexican volcanic belt: Gravity and magnetic constraints","authors":"J.O. Campos-Enríquez ,&nbsp;C. Vázquez-Domínguez ,&nbsp;J.D. Keppie ,&nbsp;W. Quintero ,&nbsp;J.M. Espinosa-Cardeña","doi":"10.1016/j.jvolgeores.2024.108163","DOIUrl":"10.1016/j.jvolgeores.2024.108163","url":null,"abstract":"<div><p>The Trans-Mexican Volcanic Belt (TMVB) stretches from the Gulf of Mexico up to Pacific Ocean. Its eastern portion is in contact with the Mixteca and Oaxaca terranes (to the south), and with the Sierra Madre Oriental (SMOr) thrust and fold belt (to the north). We conducted a gravity and magnetic study to establish the tectonic fabric and major characteristics of the basement beneath the volcanic and sedimentary cover of this volcanic province. Accordingly, we have established the existence of NE-, W-, and NW-trending lineaments. The most abundant lineaments have mean NW-SE orientation and mark portions of the Rio Actopan and Agua Blanca faults along the southern rim of the Sierra Madre Oriental, and the thrust front of the Cordoba platform. Noteworthy, the most conspicuous set of NW-SE lineaments is interpreted as associated with a major tectonic weakness zone from eastern TMVB that extends from the Apan monogenetic volcanic field, in the northwest, to the Pico de Orizaba, in the southeast, where it merges with thrust front of the Cordoba platform. Our gravity modelling indicates these lineaments are expressions of faults that juxtapose blocks of different crystalline basements. Here we interpret, that this regional tectonic lineament controlled the emplacement of TMVB Cenozoic volcanism (i.e., Acoculco caldera, Tlaxco range, Cerro Grande volcano, Las Derrumbadas domes. A major depression occupies the Mixteca-Oaxaca contact zone with the Huastecan pre-Mesozoic crystalline basement that underlies the Sierra Madre Oriental thrust and fold belt. Convergence in the northern Tehuacán Valley of the major lineament here established and faults of southern Mexico (i.e., the Oaxaca Fault) indicates a change of tectonic regime from a transpression in the south, to an extension in eastern TMVB.</p></div>","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"454 ","pages":"Article 108163"},"PeriodicalIF":2.4,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0377027324001550/pdfft?md5=405cb490e345b3226dcce77712cd3096&pid=1-s2.0-S0377027324001550-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142011852","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":"Very-long-period seismicity associated with the 2009–2015 reawakening of Cotopaxi Volcano, Ecuador","authors":"Indira Molina ,&nbsp;Hiroyuki Kumagai ,&nbsp;Mario Ruiz ,&nbsp;Stephen Hernández ,&nbsp;Patricia Mothes ,&nbsp;Gabriela Arias ,&nbsp;Joan Andújar","doi":"10.1016/j.jvolgeores.2024.108150","DOIUrl":"10.1016/j.jvolgeores.2024.108150","url":null,"abstract":"<div><p>Cotopaxi is a large, ice-capped stratovolcano located in the Ecuadorian Andes. After 72 years of repose, Cotopaxi erupted on August 14, 2015. The precursory activity included long-period (LP) events followed by volcano-tectonic (VT) earthquakes, very-long-period events accompanying LP signals (VLP/LP events), tremor, deformation and SO₂ emissions. VLP/LP events were first observed at Cotopaxi in 2002, and persistently occurred from 2009 to 2014 and during the 2015 eruptions. Previous studies of the VLP/LP seismicity suggested that these events originated by repetitive volume changes in a crack due to degassing of water from magma at a depth of 2–3 km beneath the NE flank. Based on this interpretation, we estimated the magma volumes related to individual VLP/LP events from 2009 to 2015, which were systematically extracted from continuous seismic records of the Cotopaxi broadband seismic network. Based on the accumulated magma volume and the VLP/LP activity, our study is divided into seven periods (phases A − G), during which the magma supply rate significantly fluctuated. In phase E (June 1–July 27, 2015), before the eruptions, the magma supply rate increased. Degassing at the VLP source generated gas flows in the conduit and pre-eruptive tremor, gradually drying out a shallow hydrothermal system. In phase F (July 28–September 15, 2015), we estimated the highest magma supply rate, leading to magma fragmentation at the VLP source and eruptions accompanied by tremor. In phase G (September 16–December 29, 2015), the magma supply rate decreased, and overall eruptive activity, VLP/LP events, and tremor gradually waned. These results indicate that the VLP/LP events were likely generated by degassing from magma supplied to the VLP source through an intruded dike before and during the eruptions. The VLP/LP activity provides critical useful information about the magma supply rates that controlled eruptive and gas emission activity at Cotopaxi during this period and may help to constrain magma volumes during future reactivations.</p></div>","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"453 ","pages":"Article 108150"},"PeriodicalIF":2.4,"publicationDate":"2024-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141942571","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 and polycyclic nature of a maar-diatreme volcano as constrained by changing external factors","authors":"Mátyás Hencz ,&nbsp;Károly Németh ,&nbsp;Tamás Spránitz ,&nbsp;Tamás Biró ,&nbsp;Dávid Karátson ,&nbsp;Márta Berkesi","doi":"10.1016/j.jvolgeores.2024.108158","DOIUrl":"10.1016/j.jvolgeores.2024.108158","url":null,"abstract":"<div><p>The volcanic evolution of Szent György Hill in the Miocene-Pleistocene Bakony–Balaton Highland Volcanic Field (BBHVF) is examined. Image analysis of cut rock surfaces was conducted to reveal the ratio of different juvenile and lithic components within the pyroclastic samples collected from different layers of the pyroclastic sequence. Results suggest decreasing phreatomagmatic activity over time, with a shift to magmatic-dominated eruptions represented by decreasing ratio of the sideromelane volcanic glass and increasing ratio of the magmatically-fragmented components (basaltic clasts, tachylite) successively. The changing water supply is inferred to have been played a crucial role in changes of eruption style due to the variations of external water availability from the pre-volcanic porous-media aquifers of Miocene siliciclastic sedimentary rock-dominated substrate. The eruptive history of the Szent György Hill is characterized by distinct phases starting with an initial phreatomagmatic eruption in water-saturated clastic sediments forming a shallow maar crater accompanied with a formation of a protodiatreme. Once the eruption locus reached the local karst water level, the phreatomagmatic explosions became sustained as recorded in the tephra succession by an increased accidental lithic content and the presence of ash aggregates indicating vapor-rich ejecta and ash accretion. The depletion of external water supply generated a subsequent magmatic explosive phase with lava effusion within the newly formed crater, building confined lava accumulation within. During the last phase of the eruptive sequence, phreatomagmatism was renewed, building up an intra-maar tuff ring, and finally followed by a spatter cone after a renewed repeated phreatomagmatic-magmatic transition. This study highlights the polycyclic nature of Szent György Hill's volcanic activity creating a complex volcanic edifice and suggesting a common eruption scenario for small-volume eruptions within combined aquifers that are dominated by the thick topmost porous media over high water yield karstic systems. These findings emphasize the role of eruption dynamics of monogenetic volcanic systems controlled by combined aquifer influence driven not only by the pure external conditions but also the evolving crater's hydrogeology.</p></div>","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"453 ","pages":"Article 108158"},"PeriodicalIF":2.4,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0377027324001501/pdfft?md5=0ea93d8a3ddb0707000f9884844aaac5&pid=1-s2.0-S0377027324001501-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141954147","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":"Water-rock interaction and magmatic contribution in thermal fluids of the Southern Volcanic Zone, Chile: Insights from Li, B and Sr isotopes","authors":"Sebastian Rivas ,&nbsp;Pablo Sanchez-Alfaro ,&nbsp;Fernanda Alvarez-Amado ,&nbsp;Alida Perez-Fodich ,&nbsp;Linda Godfrey ,&nbsp;Pablo Becerra ,&nbsp;Daniele Tardani ,&nbsp;Pamela Perez-Flores ,&nbsp;Felipe Aron ,&nbsp;Catalina Fica ,&nbsp;Carolina Munoz-Saez ,&nbsp;Ryan Mathur","doi":"10.1016/j.jvolgeores.2024.108149","DOIUrl":"10.1016/j.jvolgeores.2024.108149","url":null,"abstract":"<div><p>In the Southern Volcanic Zone of Chile (SVZ, 33–46°S) the interaction between regional fault systems and volcanic centers forms high enthalpy geothermal systems. This study aims to understand the hydrogeochemical processes (e.g., water mixing and water-rock interaction) that control the sources and distribution of Li, B and Sr in geothermal conditions. We selected two high-enthalpy hydrothermal systems that host diverse geothermal features, including boiling springs, fumaroles and geysers: Alpehue and Puyehue-Cordón Caulle. We used a combination of geochemical and isotopic methods, including stable isotopes of lithium (δ⁷Li), boron (δ¹¹B) and strontium (⁸⁷Sr/⁸⁶Sr) in a set of samples from thermal emissions, river waters and volcanic rocks. We analyze the potential sources of dissolved boron, lithium and strontium, and the hydrogeochemical processes that control their behavior in the systems. At Alpehue, geothermal fluids showed isotopic compositions (δ⁷Li ≈ +0.5‰, δ¹¹B ≈ −3.3‰) similar to those in volcanic rocks (δ⁷Li = +1.39‰, δ¹¹B = −2.2‰), suggesting high-temperature water-rock interaction. At Puyehue-Cordón Caulle, the isotopic signal varies inside the large-scale volcanic system: at the steam-heated zone, composed of high temperature features (fumaroles and mud pools) and affected by argillic alteration, waters have boron isotopic signals similar to altered rocks (δ¹¹B ≈ +15‰), while lithium matched the signal of magmatic fluids (δ⁷Li ≈ −2.0‰). In contrast, peripheral bicarbonate springs (T ∼ 50 °C) indicate equilibrium with a deep neutral geothermal reservoir, showing the signal of fresh volcanic rocks (δ⁷Li ≈ +5.9‰; δ¹¹B ≈ −2.2‰) but with very low Li and B concentrations due to mixing with cold surficial waters. The results support a model where geothermal water acquires the isotopic signal from the host rocks, with a variable contribution of magmatic fluids, which is enhanced in steam-heated water conditions. The multi-isotopic analysis conducted in this study identified three main processes controlling the distribution of Li, B and Sr: (1) heat-fluid-rock interaction, controlled by the isotopic signature of each hosting rock, (2) mixing with magmatic fluids, presumably influenced by regional fault systems, and (3) hydrothermal alteration, influencing rock leaching and imprinting its isotopic signature on thermal water.</p></div>","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"453 ","pages":"Article 108149"},"PeriodicalIF":2.4,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141942443","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":"Deep-seated gravity instability of the southern apron of the Ischia volcanic island (Tyrrhenian Sea, Italy)","authors":"Giovanni de Alteriis ,&nbsp;Crescenzo Violante ,&nbsp;Fabrizio Pepe","doi":"10.1016/j.jvolgeores.2024.108148","DOIUrl":"10.1016/j.jvolgeores.2024.108148","url":null,"abstract":"<div><p>Ischia Island is an active volcano representing the emerged sector of an <em>E</em>-W trending volcanic ridge largely extending undersea. Its collapsing behaviour, mainly in the form of fast-moving, terrestrial and submarine debris avalanches, has been recognized during the Holocene, but much less is known about previous gravity-driven processes. Using high-resolution multibeam bathymetric data and seismic reflection profiles, we provide evidence that the Island's southwestern flank has been involved in a slow-moving, deep-seated slope deformation that has displaced large volumes of its apron since the Late Pleistocene and until very recent or contemporary times. A long tongue of deformed seafloor, spreading up to 45 km from the Island over an area of 330 km², between 500 and 1300 m water depths, has been detected along its southwestern slope. Different types of mass movements, genetically associated with each other, characterize this landslide: 1) a basal slump anticline, corresponding to a bulge on the bathymetry detaching at about 400 m sub-bottom depth; 2) an intermediate-mass movement chiefly consisting of debris avalanches and debris/turbiditic flows; 3) an upper mass movement consisting of hundred-metre size slumps detaching at relatively shallow depths. Conservative estimates indicate that at least 50 km³ of volcano-clastic and hemipelagic deposits have been mobilized, most of which comprise the basal slump anticline. This submarine landslide can be explained as a gravity failure of the continental slope unrelated to volcanism or rather as a process related to the dynamics of the volcanic edifice, which would imply volcano-spreading.</p></div>","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"453 ","pages":"Article 108148"},"PeriodicalIF":2.4,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141942444","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":"Raman spectra of oxidized sulfur species in hydrothermal fluids","authors":"Christian Schmidt ,&nbsp;Sandro Jahn","doi":"10.1016/j.jvolgeores.2024.108146","DOIUrl":"10.1016/j.jvolgeores.2024.108146","url":null,"abstract":"<div><p>Raman spectroscopic determination of sulfur species molalities in hydrothermal fluids requires correct assignment and knowledge of the scattering efficiencies of Raman bands. Therefore, we studied the Raman spectra of NaHSO₄ and H₂SO₄ solutions experimentally to 700 °C, and of Na₂SO₄, NaHSO₄, H₂SO₄, and H₂SO₃ solutions by ab initio molecular dynamics simulation at 727 °C. The results indicate that the scattering efficiencies of the <em>ν</em>_s(SO₃), ν_as(SO₃), and ν(S–OH) Raman bands of HSO₄⁻(aq) depend on the H⁺ activity. The asymmetric shape of the ν_s(SO₃) Raman band of HSO₄⁻(aq) becomes more symmetric with increasing temperature, which correlates with decreasing hydrogen bonding in the molecular environment. Proton activity and ion pairing do not have a large effect on the change in the band asymmetry with temperature, and a resonance effect on the band shape is not observed. Therefore, we attribute the asymmetric shape of the ν_s(SO₃) Raman band of HSO₄⁻(aq) mostly to hydrogen bonding of the proton in the H–OSO₃⁻ molecule with water in its environment. The AIMD simulations clarify assignments of Raman bands of H₂SO₄⁰, specifically to ν_s(SO₂) and ν_as(SO₂) at ∼1140 cm⁻¹ and ∼1370 cm⁻¹, to ν_s(SO₄) and ν_as(SO₄) at ∼970 cm⁻¹ and ∼1220 cm⁻¹, and to ν_s(S–(OH)₂) and ν_as(S–(OH)₂) at ∼750 cm⁻¹ and ∼840 cm⁻¹. In addition, the experiments showed that diamond is not inert to H₂SO₄ at high temperatures as reduction of S(VI) to S(IV) produces SO₂⁰ and oxidation of diamond generates CO₂⁰.</p></div>","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"454 ","pages":"Article 108146"},"PeriodicalIF":2.4,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0377027324001380/pdfft?md5=440e4ed03a45bd5364ba185af336b023&pid=1-s2.0-S0377027324001380-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141998472","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}