Journal of Volcanology and Geothermal Research最新文献

{"title":"Paleomagnetic study of the Capo di Bove lava flow, Rome, Italy","authors":"Anita Di Chiara ,&nbsp;Priyeshu Srivastava ,&nbsp;Fabio Florindo ,&nbsp;Mario Gaeta ,&nbsp;Fabrizio Marra ,&nbsp;Leonardo Sagnotti ,&nbsp;Raquel Bonilla Alba ,&nbsp;Ines Tescione ,&nbsp;Alfredo Sorice ,&nbsp;Lilla Spagnuolo","doi":"10.1016/j.jvolgeores.2024.108202","DOIUrl":"10.1016/j.jvolgeores.2024.108202","url":null,"abstract":"<div><div>The Capo di Bove (CDB) lava flow was emplaced at ∼277 ka during the Faete eruptive Phase of Colli Albani volcanic district near the city of Rome. The CDB lava has a historical significance as it provided the slabs used in the paving of the ancient Appian Way, built in the 4^th century BCE. Puzzlingly beyond the seventh milestone, the ancient Appian Way deviates briefly from an otherwise straight SE-NW direction, abandoning the top of the lava flow and resuming its elevation and the SE-NW trend within less than 1 km. This peculiarity raised a question as to whether the deviation could have been the result of a tectonic deformation caused by a (buried) fault. To test this hypothesis, we sampled the CDB lava flow at four locations over a ∼ 10 km transect near the ancient Appian Way around the bend and performed a detailed rock magnetic, paleomagnetic, and petrographic study. Rock magnetic data indicate that pseudo-single-domain magnetite and low-Ti titanomagnetite particles are the main magnetic carriers for three sampling locations, located in freshly cut quarries, which reliably recorded the paleomagnetic field at the time of emplacement. Conversely, the samples collected in the upper part of the lava flow, within the bent segment of the ancient Appian Way, show multi-domain low- and moderate-Ti titanomagnetites as main magnetic carriers which fail to record a paleomagnetic direction. Anisotropy of magnetic susceptibility data are consistent with an overall CDB lava flow direction from SE to NW and the paleomagnetic directional data from the three reliable sampling sites are statistically indistinguishable. Hence, data from this study show no evidence of post-emplacement tectonic rotations. We suggest that the origin of the bend could be identified in the pre-existing morphology (for the lava flow path) and in historical reasons (for the ancient Appian Way).</div></div>","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"455 ","pages":"Article 108202"},"PeriodicalIF":2.4,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142426791","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":"Seismic structure beneath Ebeko Volcano and surrounding areas of Paramushir Island (Kuril Arc) inferred from local earthquake tomography","authors":"Ivan Koulakov ,&nbsp;Viktoria Komzeleva ,&nbsp;Irina Medved ,&nbsp;Tatyana Stupina ,&nbsp;Angelika Novgorodova","doi":"10.1016/j.jvolgeores.2024.108201","DOIUrl":"10.1016/j.jvolgeores.2024.108201","url":null,"abstract":"<div><div>Paramushir is a large northernmost island of the Kuril Arc in the Russian Far East. Here, we study the northern part of Paramushir, which is dominated by the Vernadsky Ridge with an altitude of around 1000 m above sea level. This ridge is composed of a series of Pleistocene and Holocene volcanoes and includes the presently active Ebeko Volcano, which exhibits frequent phreatomagmatic eruptions and ongoing fumarolic activity. Studying the internal structure beneath Northern Paramushir is important to understand the interrelationship of magmatic, hydrothermal, hydrological and geological processes below Ebeko Volcano. We use seismic data of a portable network consisting of 20 broadband stations installed for one year from the summer 2021 to 2022 and one permanent station in the city of Severo-Kurilsk. We performed the local earthquake tomography inversion, which provided the distributions of Vp, Vs, Vp/Vs and local seismicity in an area of northern Paramushir with lateral extent of ∼20 km and depth of a ∼ 15 km. The results of several tests gave the information about the resolution limitations of the computed model, which were taken into account during its interpretation. In the resulting model, the coexistence of low Vp, high Vs, low Vp/Vs and a seismicity cluster down to ∼10 km below Ebeko indicates the presence of a large gas-saturated area that was formed due to the contacts of liquid fluids with hot magmatic intrusions. The western border of this area coincides with the location of Verkhne-Yurievsky hot water sources and possibly highlights the path of fluids traveling around the hot body below Ebeko. Below the upper part of the eastern slope, we observe a shallow anomaly of low Vs and high Vp/Vs indicating the presence of a near-surface aquifer, confirming the previous results of ambient noise tomography. Below the lower part of the eastern slope, a nearly vertical anomaly of low Vs and high Vp/Vs may represent a fault zone, which is also marked on the surface by a series of lineaments.</div></div>","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"455 ","pages":"Article 108201"},"PeriodicalIF":2.4,"publicationDate":"2024-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142427024","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 viscous-brittle transition in flowing crystal-bearing volcanic dome lavas","authors":"Fabian B. Wadsworth ,&nbsp;Jérémie Vasseur ,&nbsp;Michael J. Heap ,&nbsp;Jackie E. Kendrick ,&nbsp;Claire E. Harnett ,&nbsp;Annabelle Foster ,&nbsp;Daniel Weller ,&nbsp;Bettina Scheu ,&nbsp;Anthony Lamur ,&nbsp;Luiz Pereira ,&nbsp;Donald B. Dingwell ,&nbsp;Yan Lavallée","doi":"10.1016/j.jvolgeores.2024.108198","DOIUrl":"10.1016/j.jvolgeores.2024.108198","url":null,"abstract":"<div><div>The ascent and advance of volcanic dome lava is non-linear and viscoelastic. There exists a mismatch between current theoretical approaches to dome lava rheology, which are based on rheological laws for viscous suspensions, and empirical experimental approaches to convolved viscous-brittle deformation, which show mixed evidence for simultaneous lava flow and fracturing. The missing requirement is a unified framework for understanding the transition between micro-mechanical flow mechanisms that are dominantly viscous, and those that include micro-cracking in multiphase suspensions such as magmas. Here, we use high-temperature compression rheology with sample-scale acoustic emission analysis to constrain the conditions under which crystal-rich volcanic dome lava can flow by mixed viscous and brittle fracturing processes at small scales, leading to ‘crackling’ acoustic signals, even at moderate shear stresses extant in nature. Using multi-directional permeability measurements on large 60 mm diameter quenched samples of natural magmas, we show that this micro-cracking flow mechanism leads to permeability anisotropy, localizing outgassing into pathways that are off-axis relative to the direction of flow. Finally, we use a scaling approach and a database of published observations from real eruptions to upscale our findings, and show that bulk, apparently ductile flow of low-porosity dome magma is likely to involve a local mixed-mode of micro-cracking and viscous flow during the shallowest portions of ascent and during emplacement on the Earth's surface. The micro-cracking involved in lava advance divorces real crystal-bearing lava emplacement from most current rheology models based on a purely viscous micro-mechanism and shows that a revised solution for the rheology of mixed brittle-viscous flow is required. By re-examining published numerical models for dome emplacement, we demonstrate that the viscous-brittle transition can be intercepted in spatially heterogeneous zones within the dome core.</div></div>","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"457 ","pages":"Article 108198"},"PeriodicalIF":2.4,"publicationDate":"2024-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142698258","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":"Effects of cohesion and viscosity on lava dome growth following repose","authors":"Amy J. Myers ,&nbsp;Claire E. Harnett ,&nbsp;Eoghan P. Holohan ,&nbsp;John G. Ryan ,&nbsp;Edgar U. Zorn ,&nbsp;Thomas R. Walter ,&nbsp;Michael J. Heap","doi":"10.1016/j.jvolgeores.2024.108196","DOIUrl":"10.1016/j.jvolgeores.2024.108196","url":null,"abstract":"<div><div>Lava domes result from effusive eruption of high viscosity lava. These viscous lava extrusions range in shape from flat-topped domes with small height-to-width aspect ratios, to spine-like columns exhibiting large height-to-width aspect ratios. A primary control on morphology during early dome growth is thought to be the variation in rheological characteristics of extruded material. In this work, we present new scaled analogue models of lava dome growth that consider extrusion of a frictional plastic upper-conduit plug followed by viscous magma. We simulate the brittle plug using a sand-plaster mixture, the cohesion of which is varied by plaster content. We model the magma using sugar syrup, the viscosity of which is controlled by the weight percent of added crystalline sugar. The models both qualitatively and quantitatively reproduce part of the spectrum of natural dome morphology not previously obtained in most past analogue modelling studies. Model aspect ratios of 0.02 to 0.9 capture approximately 90 % of the reported aspect ratio variation in nature. Increasing plug cohesion results in extrusions with higher aspect ratios and spinier morphologies. Low viscosity fluid typically erupts through the brittle dome, whilst high viscosity fluid tends to promote endogenous growth or emerge as exogenous lobes. Particle Image Velocimetry shows that fracture localisation at the dome surface is cohesion-dependent, and eruption of fluid follows shear fractures within the dome. Where fluid remains contained within the dome, we see lateral spread leading to a wider and flatter dome morphology. Evolution of lava dome morphology, deformation, and associated hazards is guided by the complex rheological properties of the extruded material; we suggest that during episodic dome growth, these properties are largely defined in the conduit prior to their eruption.</div></div>","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"455 ","pages":"Article 108196"},"PeriodicalIF":2.4,"publicationDate":"2024-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142427023","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":"Lava flow field development and lava tube formation during the 1858–1861 eruption of Vesuvius (Italy), unravelled by historical documentation, lidar data and 3D mapping","authors":"Thomas Lemaire ,&nbsp;Daniele Morgavi ,&nbsp;Paola Petrosino ,&nbsp;Sonia Calvari ,&nbsp;Leopoldo Repola ,&nbsp;Lorenzo Esposito ,&nbsp;Diego Di Martire ,&nbsp;Vincenzo Morra ,&nbsp;Francesco Frondini","doi":"10.1016/j.jvolgeores.2024.108197","DOIUrl":"10.1016/j.jvolgeores.2024.108197","url":null,"abstract":"<div><div>Somma-Vesuvius is well known for its powerful Plinian explosive eruptions, however during the last eruptive cycle (1631–1944), persistent activity took place on the stratovolcano as mild and violent Strombolian, and effusive eruptions, forming more than one hundred lava flow fields. An important mechanism of lava transport within lava flow fields is the formation and development of lava tubes. The presence of lava tubes in a flow field can greatly increase their distance of emplacement. Observations of lava tubes at Vesuvius have been documented in historical records and speleological reports but no modern scientific studies are available. This work focuses on lava tubes formed in the compound lava flow field of the long-lived 1858 eruption (from 27 May 1858 to 12 April 1861) that was fed by seven eruptive fissures. The temporal and spatial evolution of the 1858 lava flow field was reconstructed using historical documentation. The exposed lava flow field surface was analysed using a 1-m resolution lidar Digital Surface Model (DSM). Surveys to fully digitize the interior and the overlying surface of the largest lava tube found in the 1858 lava flow field were conducted using a terrestrial laser scanner, optical cameras, and an Unmanned Aerial Vehicle (UAV). The accurate 3D model obtained was used to precisely quantify the inner dimensions and to better constrain the morphologies of the lava tube. Observed internal features were described and used to gain information on the formation and activity of the lava tube. Our data allowed us to understand that the described lava tube formed as an inflated lava flow inside which lava flowed through during an extended period ultimately draining out completely at the end of the eruption. Understanding how lava flow fields develop and how lava tubes form on Vesuvius is crucial to re-evaluate the last effusive activity of the volcano and its impact on hazard assessment.</div></div>","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"455 ","pages":"Article 108197"},"PeriodicalIF":2.4,"publicationDate":"2024-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142426939","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":"Ice-marginal volcanic sequence in Iceland found on a nondescript gradual hillslope: An unexpected record of ice thickness late in deglaciation","authors":"Audrey R. Putnam ,&nbsp;Kirsten L. Siebach ,&nbsp;Candice C. Bedford ,&nbsp;Sarah L. Simpson ,&nbsp;Michael T. Thorpe ,&nbsp;Joseph J. Tamborski ,&nbsp;Elizabeth B. Rampe","doi":"10.1016/j.jvolgeores.2024.108195","DOIUrl":"10.1016/j.jvolgeores.2024.108195","url":null,"abstract":"<div><div>Volcanism increases when glaciers melt because isostatic rebound during deglaciation decreases the pressure on the mantle, which enhances decompression melting. Anthropogenic climate change is now causing ice sheets and valley glaciers to melt around the world and this deglaciation could stimulate volcanic activity and associated hazards in Iceland, Antarctica, Alaska, and Patagonia. However, current model predictions for volcanic activity associated with anthropogenic deglaciation in Iceland are poorly constrained, in part due to uncertainties in past volcanic output over time compared to ice sheet arrangements. Further work specifically characterizing glaciovolcanic and ice-marginal volcanoes in Iceland is needed to reconstruct volcanic output during time periods with changing ice cover. Here, we describe a previously unrecognized ice-marginal volcanic sequence on a broad, gradual hillslope southeast of Langjökull and the Jarlhettur volcanic chain in Iceland's Western Volcanic Zone. Although previously mapped as interglacial lavas, canyons in this area revealed two southwest-dipping sequences of pillow-bearing tuff-breccias between pāhoehoe lava flows above modern lake Sandvatn. These pillow-bearing tuff-breccias and the quenched meter-scale cavities in coherent lava and cube-jointed facies show lavas came into contact with ice and pockets of trapped meltwater. However, clasts within the tuff-breccias include a mixture of pillow lavas and pāhoehoe fragments, requiring that the subaqueous tuff-breccia facies were derived from subaerial flows. In addition, we observed interfingering of subaerial and transitional subaqueous-subaerial pāhoehoe lava flows with the pillow-bearing tuff-breccias. We propose that during a deglaciation, subaerial lavas sourced upslope from near Skálpanes flowed downslope to the south and came into contact with thin ice north of the modern lake Sandvatn. We constrain the local ice at this time to be ∼30–50 m thick. Importantly, this finding demonstrates that ice-marginal deposits that can provide paleo-environmental constraints may be hidden in terrains without morphologically distinct glaciovolcanic edifices.</div></div>","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"455 ","pages":"Article 108195"},"PeriodicalIF":2.4,"publicationDate":"2024-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142426938","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":"New perspectives on ice forcing in continental arc magma plumbing systems","authors":"Brad S. Singer ,&nbsp;Pablo Moreno-Yaeger ,&nbsp;Meredith Townsend ,&nbsp;Christian Huber ,&nbsp;Joshua Cuzzone ,&nbsp;Benjamin R. Edwards ,&nbsp;Matias Romero ,&nbsp;Yasmeen Orellana-Salazar ,&nbsp;Shaun A. Marcott ,&nbsp;Rachel E. Breunig ,&nbsp;Ken L. Ferrier ,&nbsp;Kathryn Scholz ,&nbsp;Allie N. Coonin ,&nbsp;Brent V. Alloway ,&nbsp;Marissa M. Tremblay ,&nbsp;Sally Stevens ,&nbsp;Ivo Fustos-Toribio ,&nbsp;Patricio I. Moreno ,&nbsp;Franco Vera ,&nbsp;Álvaro Amigo","doi":"10.1016/j.jvolgeores.2024.108187","DOIUrl":"10.1016/j.jvolgeores.2024.108187","url":null,"abstract":"&lt;div&gt;&lt;div&gt;Determining how and why eruptive outputs are modulated by the loading and unloading of ice is key to understanding whether ongoing and accelerating deglaciation across mid- to high-latitudes will impact future activity at many volcanoes. Here, we address two central questions. First, does decompression of the upper crust during rapid thinning of ice sheets propel increases in eruption rates? Second, does surface loading during ice sheet growth, followed by rapid unloading during deglaciation, promote changes in magma storage conditions and compositions within the underlying magma plumbing systems? To provide new perspectives on these questions, we address the mechanics and dynamics of ice sheet-arc magma plumbing system interactions at a regional-to-local scale within the Andean Southern Volcanic Zone. Here, piedmont glacier lobes, forming the northernmost extension of the Patagonian ice sheet, have enveloped dozens of large, active, composite volcanoes as these glaciers reached local thicknesses of nearly 2 km during the local Last Glacial Maximum (LGM) between ∼35 and 18 ka, before retreating rapidly between 18 and 15 ka. Our multi-faceted review features a synthesis of existing and new field observations, laboratory measurements, and numerical simulations. Advances in &lt;sup&gt;40&lt;/sup&gt;Ar/&lt;sup&gt;39&lt;/sup&gt;Ar radioisotopic and &lt;sup&gt;3&lt;/sup&gt;He surface exposure geochronology, in conjunction with geologic mapping, facilitate reconstructions of volcanic eruptive histories spanning the last glacial-deglacial cycle and in places provide constraints on the thickness of ice at specific time slices. The magnitude and geometry of the glacial loading and unloading is captured in a climate model-driven numerical simulation that reveals spatial and temporal heterogeneities in the configuration of the northernmost Patagonian ice sheet retreat. Geological observations including dated moraine complexes, dated lava-ice contact features, and glacial erratic boulders at high altitude on volcano slopes, are consistent with this model. Deep valleys imply intense localized erosion on volcano flanks, and deposited sediment in nearby floodplains implies narrow regions of rapid sediment deposition. These observations, in conjunction with dated lava flows, provide constraints on rates and patterns of crustal loading and unloading by sediment redistribution.&lt;/div&gt;&lt;div&gt;The ice loading model, cone growth, and a sediment redistribution history inform numerical simulations of intra-crustal stress changes below the volcanic arc in response to the ice-driven and sediment-driven changes. In turn, the modeled surface loading is central to designing numerical simulations of magma reservoir responses to intra-crustal stress changes beneath the volcanoes. Following periods of subdued volcanic output, upticks in eruptive rates are found at three volcanoes during, or shortly after, the LGM. A numerical magma chamber model suggests that this behavior could be the result of a delicate ","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"455 ","pages":"Article 108187"},"PeriodicalIF":2.4,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142427021","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":"Three-dimensional interpretation of magnetotelluric data at Fogo Volcano, Azores Islands","authors":"Colin Hogg ,&nbsp;Duygu Kiyan ,&nbsp;Volker Rath ,&nbsp;Andreas Junge ,&nbsp;Philip Hering ,&nbsp;Cesar Castro ,&nbsp;Rita Carmo ,&nbsp;Rita Silva ,&nbsp;Rui Marques","doi":"10.1016/j.jvolgeores.2024.108183","DOIUrl":"10.1016/j.jvolgeores.2024.108183","url":null,"abstract":"<div><div>The resistivity structure of Fogo volcano and the seismically active Congro region of São Miguel Island has been determined by 3-D inversion from 44 magnetotelluric soundings to yield new insights into the internal architecture of this volcanic island. Following comprehensive testing of processing codes to yield optimum magnetotelluric responses from the collected time-series, a robust electrical resistivity model was obtained. Sensitivity analysis of various features from the inversion process was used to determine their reliability, and aid geological interpretation. The magnetotelluric data imaged, and provided new structural insights into the Ribeira Grande geothermal system on the northern flank of Fogo volcano, where a shallow low resistivity (1 - <span><math><mn>5</mn><mspace></mspace><mi>Ωm</mi></math></span>) region has strong correlation with borehole data, and is shown to be an excellent proxy for mapping temperature and clay alteration mineralogy. Beneath the central edifice of Fogo volcano and also throughout the Congro region, the geology is very resistive, however the new magnetotelluric observations do not yield any further constraints on the origin of the seismicity that poses threats to the local populations residing on this hazardous island.</div></div>","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"455 ","pages":"Article 108183"},"PeriodicalIF":2.4,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142311949","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":"Accurate epicenter locations in the vicinity of the seamount by using BBOBS array data","authors":"Tetsuya Aoyama,&nbsp;Nozomu Takeuchi,&nbsp;Yosuke Aoki","doi":"10.1016/j.jvolgeores.2024.108186","DOIUrl":"10.1016/j.jvolgeores.2024.108186","url":null,"abstract":"<div><p>A Mw = 6.4 earthquake, possibly related to submarine volcanism, occurred on October 23, 2006, in the vicinity of Monday Seamount, located in the Izu-Bonin-Mariana arc. Despite the size of the earthquake, the precise location of aftershocks is intractable with the routine data processing because of poor station coverage and complex waveforms traversing the oceanic lithosphere. This study overcomes these problems by using the Broadband Ocean Bottom Seismometer (BBOBS) array data with better azimuthal coverage and by developing new methods to detect the P-wave arrival time to locate the aftershocks precisely. Most of the relocated epicenters are located in the rift zone next to the edifice of the seamount. We interpret this pattern as the seismic activity induced by stress perturbation due to the dike intrusion.</p></div>","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"455 ","pages":"Article 108186"},"PeriodicalIF":2.4,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0377027324001781/pdfft?md5=a65adde3198990a7d344323b5a743965&pid=1-s2.0-S0377027324001781-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142162706","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":"Statistical analysis of the ground deformation of Vulcanian explosions at Sakurajima volcano, Japan","authors":"Kyoka Ishii ,&nbsp;Masato Iguchi","doi":"10.1016/j.jvolgeores.2024.108185","DOIUrl":"10.1016/j.jvolgeores.2024.108185","url":null,"abstract":"<div><p>The forecast of pulsatory explosions during volcanic unrest periods is an essential issue for the assessment and mitigation of volcanic hazards. Although various precursors are detectable through geophysical and geochemical monitoring, difficulties remain in precisely constraining possible scenarios. A probabilistic approach is effective in assessing risk while considering various uncertainties. Sakurajima volcano characterized by frequent Vulcanian activity is one of the suitable fields for the probabilistic forecast of pulsatory explosions. Their inflation-deflation patterns of ground deformation related to Vulcanian explosions are useful for evaluating the imminence and size of the next event. The large database obtained from its vigorous activity can contribute to statistical analysis. In this study, aiming the probabilistic forecast of the timing and size of explosions, we investigated the duration of inflation and volume changes at the pressure source using strain records of over 5000 events of Sakurajima volcano. Then, a stochastic model was estimated to explain the distribution of these events. The log-logistic distribution was found to be an appropriate model for data distribution, indicating the presence of competing processes, such as pressurization and depressurization, in the conduit. The model parameters of the log-logistic distribution temporally fluctuated reflecting the volcanic activity, especially increasing the magma supply from a deep region. We also suggested a methodology to constrain the probabilities of the likely timing and size of an imminent explosion using real-time strain monitoring and an estimated model distribution. Although some improvements would be needed for practical forecasting, our approach could be useful in predicting possible ash hazards.</p></div>","PeriodicalId":54753,"journal":{"name":"Journal of Volcanology and Geothermal Research","volume":"455 ","pages":"Article 108185"},"PeriodicalIF":2.4,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S037702732400177X/pdfft?md5=360453948044bc002966a28ee2e532de&pid=1-s2.0-S037702732400177X-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142229018","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}