https://www.jvolcanica.org/ojs/index.php/volcanica/issue/feed Volcanica 2024-04-25T04:06:58+00:00 Jamie Farquharson editor@jvolcanica.org Open Journal Systems <p><em>Volcanica</em>&nbsp;publishes high-quality, rigorously peer reviewed research pertaining to volcanology and related disciplines, while eliminating submission fees and keeping content freely accessible.</p> https://www.jvolcanica.org/ojs/index.php/volcanica/article/view/239 Insights on the state of stress in the mantle beneath Pahala, Hawai‘i 2023-10-31T23:47:38+00:00 John D. Wilding jwilding@caltech.edu Zachary E. Ross zross@caltech.edu <p>Magma supply rates from the mantle to Hawaiian volcanoes serve as an important control on eruptive behavior at the surface. The Pa ̄hala Sill Complex, a collection of magma-bearing, seismogenic structures at 40 km depth beneath Hawai‘i, presents an opportunity to elucidate interactions between stress and magma transport processes in the mantle. We invert for full moment tensors of sill earthquakes and identify predominantly shear mechanisms with persistent tensile faulting components. Slip occurs in-plane with the sill structures. Pressure axes are radially oriented about a point near Mauna Loa, consistent with a stress field generated by a flexural load. Together, these observations suggest that magma flux through the sill structures generates seismicity by increasing pore pressure and promoting slip. Our results suggest that stress changes in mantle structures may enable fluctuations in magma supply rates to the surface over short timescales.</p> 2024-01-18T00:00:00+00:00 Copyright (c) 2024 John D. Wilding, Zachary E. Ross https://www.jvolcanica.org/ojs/index.php/volcanica/article/view/207 Rapid growth and catastrophic destruction events of Planchón Volcano, Southern Andes 2023-09-19T04:54:20+00:00 José Antonio Naranjo jose.naranjo@sernageomin.cl Jorge Romero jorge.romero@uoh.cl Juan Pablo Contreras juan.contreras@sernageomin.cl Yuji Orihashi oripachi@hirosaki-u.ac.jp Kevin Scott kwscott@usgs.gov Miguel Haller haller@cenpat.edu.ar Hirochika Sumino sumino@igcl.c.u-tokyo.ac.jp <p>During the Late Pleistocene-to-Holocene, the mafic Planchón volcano (35.2 °S, Southern Andes) experienced two important destructive events: a sector collapse to the west and a multiphase explosive eruption transforming the east summit area. We provide new field and laboratory evidence, including geochemical, geochronologic, and geological-morphological analysis, to reconstruct the evolution, triggering mechanisms, and physical parameters of these events.The lateral collapse (48~ka BP) was mainly predisposed by a tectonically westward-inclined substratum and rapid edifice growth rates (0.3–0.48 km<sup><span class="annotation superscript" data-id="superscript_1">3</span></sup> ka<sup><span class="annotation superscript" data-id="superscript_2">-1</span></sup>). The resulting Planchón-Teno debris avalanche became valley-confined traveling at c. 260 km h<sup><span class="annotation superscript" data-id="superscript_3">-1</span></sup> up to 95 km distance and forming an 8.6 ± 1.3 km<sup><span class="annotation superscript" data-id="superscript_4">3</span></sup> deposit. The resulting 4.1 km wide amphitheater was later destroyed at c. 7 ka BP by the multiphase Valenzuela phreatomagmatic eruptions, forming a c. 2.5 km diameter caldera. The case of the Planchón volcano warns that rapidly growing mafic volcanoes imply a substantial catastrophic hazard increase for the surrounding areas.</p> 2024-01-30T00:00:00+00:00 Copyright (c) 2024 José Antonio Naranjo, Jorge Romero, Juan Pablo Contreras, Yuji Orihashi, Kevin Scott, Miguel Haller, Hirochika Sumino https://www.jvolcanica.org/ojs/index.php/volcanica/article/view/235 Magma residence time, ascent rate and eruptive style of the November ash-laden activity during the 2021 Tajogaite eruption (La Palma, Spain) 2023-11-20T23:49:34+00:00 Barbara Bonechi barbara.bonechi@manchester.ac.uk Margherita Polacci margherita.polacci@manchester.ac.uk Fabio Arzilli fabio.arzilli@unicam.it Jorge Romero jorge.romero@uoh.cl Jonathan Fellowes jonathan.fellowes@manchester.ac.uk Mike Burton mike.burton@manchester.ac.uk <p>We combined compositional analyses, crystal size distributions and geothermobarometry of tephra erupted during the 2021 Tajogaite eruption (La Palma, Spain), focusing on samples collected in November 2021 associated with a period of abundant ash emission characteristic of the second half of the eruption (from October onwards). Magma erupted in November exhibits a more primitive basanitic composition than the earlier magma. Crystallisation temperatures range between ~1100–1160 °C (H<sub>2</sub>O = 1–3 wt.%) for phenocrysts and microphenocrysts, with corresponding pressures indicating depths from ~10 to ~30 km. Crystal size distribution analysis reveals short (minutes) residence times for plagioclase. Finally, magma ascent velocities (~0.01–0.3 m s<sup>−1</sup>) suggest acceleration and fragmentation in the shallowest part of the conduit. Our results suggest that the trigger of the November explosive activity can be attributed to complex feedback between gas emission rates, changes in conduit geometry, and magma ascent rate.</p> 2024-01-31T00:00:00+00:00 Copyright (c) 2024 Barbara Bonechi, Margherita Polacci, Fabio Arzilli, Jorge Romero, Jonathan Fellowes, Mike Burton https://www.jvolcanica.org/ojs/index.php/volcanica/article/view/232 Dynamics of magmatic intrusion: what can we learn from the comparison of analog and numerical models? 2023-10-19T15:41:21+00:00 Séverine Furst sfurst@geomar.de Virginie Pinel virginie.pinel@univ-smb.fr Francesco Maccaferri francesco.maccaferri@ingv.it <p>This study investigates the dynamics of magmatic intrusions based on the joint analysis of analog and numerical models. By injecting different fluids from the bottom of a solidified gelatin block, we simulate the propagation of magmatic intrusions through the crust and record their shapes, trajectories, and velocity as they rise towards the surface. Additionally, we make use of a 2D fluid-filled crack propagation model constrained by our experimental observations. The numerical simulations demonstrate that our viscous fluid-filled crack experiments, conducted with silicon-oil injections, propagate in the same regime as typical basaltic intrusions. The comparison between analog and numerical results allow us to define the domain of validity of the numerical model and its limit of applicability. This study provides new insights into the processes that control the propagation of magmatic intrusions and our ability to reproduce them using analog and numerical models.</p> 2024-02-02T00:00:00+00:00 Copyright (c) 2024 Séverine Furst, Virginie Pinel, Francesco Maccaferri https://www.jvolcanica.org/ojs/index.php/volcanica/article/view/198 Numerical simulations of the mingling caused by a magma intruding a resident mush 2023-09-19T04:51:44+00:00 Alexandre Carrara carrara.alexandre.univ@gmail.com Alain Burgisser alain.burgisser@univ-smb.fr George W. Bergantz bergantz@uw.edu <p>Currently, our ability to interpret the mechanics of magma mingling and mixing is limited by an incomplete understanding of the modes of mixing across all melt fractions and compositions. Here, we present numerical simulations of the emplacement of crystal-free magma in crystal-rich reservoirs employing a computational fluid dynamics and discrete element method (CFD–DEM). We performed two runs corresponding to the emplacement of basalt into two end-member types of magmas mush (basaltic and dacitic). We found that the intruded volumes have similar shapes and are surrounded by a halo where the crystal volume fraction of the mush is lower. The dynamics of intruded melt are, however, different. Importantly, the mingling of the intruded and host materials starts after emplacement and consists in the incorporation of mush material into the intruded magma. Our findings imply that purely thermo-mechanical processes controlled by grain-scale dynamics are sufficient to explain fundamental aspects of recharge.</p> 2024-02-06T00:00:00+00:00 Copyright (c) 2024 Alexandre Carrara, Alain Burgisser, George W. Bergantz https://www.jvolcanica.org/ojs/index.php/volcanica/article/view/233 An appraisal of the observed crystallinities of volcanic materials 2024-01-07T18:17:03+00:00 Hannah Shamloo shamlooh@cwu.edu Adam Kent Adam.Kent@oregonstate.edu <p>There is a broad consensus that magma eruptibility—the ability of magma stored in the subsurface to erupt onto Earth's surface—is strongly controlled by viscosity. Related to this, a critical parameter that controls viscosity is crystallinity. However, there is uncertainty in the crystallinities that distinguish eruptible from non-eruptible magmas, and whether highly crystalline magmas (&gt;60 vol.%) could be erupted in some conditions. An underutilized but important source of information for understanding this relationship is the observed crystallinities in erupted volcanic materials, which by definition represent a set of eruptible magmas. Here we present a compilation of reported crystallinities for nearly 1000 volcanic samples of differing composition, tectonic setting, and eruption style, which provides valuable insight into the fundamental mechanisms which drive eruptions. Overall, the 95th percentile crystallinity value of our full dataset is 57 vol.%, and \&gt;99 % of all non-dome samples have crystallinity ≤53 vol.%. This suggests that 50–60 vol.% crystallinity represents a fundamental limit for eruptibility for most volcanic rocks. Some dome samples are clear exceptions to this and are erupted with considerably higher crystallinities. There is also a significant correlation between crystallinity and whole rock SiO<sub>2</sub> content as observed previously, but a shallow slope suggests whole rock and melt silica content have less impact on critical crystallinity for erupted magma than previously thought. Melt viscosity (as a function of SiO<sub>2</sub>, temperature, and H<sub>2</sub>O content) and crystallinity both play important roles on increasing effective viscosity, where melt viscosity plays a more important role at low crystal fractions, and crystallinity plays a more important role at crystallinities greater than ~40 vol.%.</p> 2024-02-23T00:00:00+00:00 Copyright (c) 2024 Hannah Shamloo, Adam Kent https://www.jvolcanica.org/ojs/index.php/volcanica/article/view/208 Reconciling petrologic magma ascent speedometers for the June 12th, 1991 eruption of Mt. Pinatubo, Philippines 2023-06-27T08:57:22+00:00 Megan Harris dr.meganharris22@gmail.com Behnaz Hosseini behnazhosseini@montana.edu Madison Myers madison.myers@montana.edu Logan Bouley bouley.logan@gmail.com <p style="font-weight: 400;">We investigate whether decompression rates derived from three often-disparate petrologic techniques (microlites, bubbles, and melt embayments) can be reconciled or integrated for a more complete understanding of magma ascent in the conduit. We focus on the well-studied and -documented earliest Plinian eruptions (June 12, 1991) of Mount Pinatubo. Using a newly developed two-stage decompression-diffusion model, volatile profiles in quartz-hosted embayments reveal an initial stage of decompression nearly two orders of magnitude slower than final rates. In applying time-integrated models of microlite and bubble nucleation and growth, initial decompression rates from embayments are supported by microlite modeling results, whereas final rates are in close agreement with bubble number densities. This consistency and continuity between speedometers supports the sensitivity of different petrologic recorders to specific regions of the conduit system and highlights the fidelity of embayments as recorders of decompression throughout the entire conduit. Ascent timescales derived from Pinatubo embayments range from hours to days, coinciding with the visual onset of lava effusion leading to explosive activity.</p> 2024-03-01T00:00:00+00:00 Copyright (c) 2024 Megan Harris, Behnaz Hosseini, Madison Myers, Logan Bouley https://www.jvolcanica.org/ojs/index.php/volcanica/article/view/217 Accurate hindcasting of explosive eruptions at Whakaari, New Zealand 2023-08-29T08:10:50+00:00 John Stix stix@eps.mcgill.ca Craig Miller C.Miller@gns.cri.nz Yajing Liu yajing.liu@mcgill.ca <p>Phreatic eruptions are small, sudden events, commonly with few precursory signals. They are driven by interactions between magmatic and hydrothermal processes at shallow levels beneath the surface. Here we show that a sequence of banded tremor events, which occurred several weeks before the 9 December 2019 eruption of Whakaari (White Island), New Zealand, can be used to hindcast this eruption. The banded tremor sequence reveals a progressively decreasing time interval between tremor bands. Extrapolating the tremor bands to a time interval of zero provides an accurate estimate, at least one week prior to the eruption, to within 10.2 hours of when the eruption would occur, with a 2.8-day range between 95 % confidence intervals. A similar set of tremor signals appeared before the 27 April 2016 eruption, and these signals provide a very accurate hindcast of this eruption to within 2.61 hours, with a 2.2-day range between 95 % confidence intervals. Our analysis indicates that this potential forecasting approach may prove useful for successfully and accurately forecasting future eruptions at Whakaari. The approach also may be applicable to other volcanoes similar to Whakaari which experience sudden phreatic and phreatomagmatic eruptions. </p> 2024-03-12T00:00:00+00:00 Copyright (c) 2024 John Stix, Craig Miller, Yajing Liu https://www.jvolcanica.org/ojs/index.php/volcanica/article/view/221 The relationship between large earthquakes and volcanic eruptions: A global statistical study 2024-01-22T07:45:40+00:00 Alex Jenkins alexander.jenkins@bristol.ac.uk Alison Rust alison.rust@bristol.ac.uk Juliet Biggs juliet.biggs@bristol.ac.uk <p>It is now generally accepted that large earthquakes can promote eruptions at nearby volcanoes. However, the prevalence of “triggered” eruptions, as well as the distance and timescale over which triggering occurs, remain unclear. Here, we use modern global earthquake and eruption records to compare volcanic eruption rates before and after large earthquakes with the time- averaged background eruption rate. We quantify the significance of observed deviations from the average eruption rate using Monte Carlo simulations. To integrate our findings with previous eruption triggering studies, we systematically vary the earthquake magnitudes we consider, as well as the distances and timescales used to calculate eruption rates. We also investigate the effects of earthquake depth and slip orientation. Overall, we find that post-earthquake eruption rates are around 1.25 times the average eruption rate within 750 km and one year following M<sub>w</sub> ≥ 7 earthquakes, with above-average post-earthquake eruption rates possibly lasting for two to four years. By contrast, pre-earthquake eruption rates are around 0.9 times the average eruption rate within 750 km and182 days before M<sub>w</sub> ≥7 earthquakes. Furthermore, deep earthquakes (≥7 0km) appear to more strongly affect eruption rates than shallow earthquakes, while earthquake slip orientation is also important. Further study of the relationships reported here represents a good opportunity to improve our understanding of tectono-magmatic relationships.</p> 2024-03-22T00:00:00+00:00 Copyright (c) 2024 Alex Jenkins, Alison Rust, Juliet Biggs https://www.jvolcanica.org/ojs/index.php/volcanica/article/view/264 Craters of habit: Patterns of deformation in the western Galápagos 2023-11-29T01:20:25+00:00 Eoin Reddin earere@leeds.ac.uk Susanna Ebmeier s.k.ebmeier@leeds.ac.uk Marco Bagnardi mbagnardi@usgs.gov Andrew F. Bell A.Bell@ed.ac.uk Pedro Espín Bedón eepabe@leeds.ac.uk <p>The western Galápagos islands of Fernandina and Isabela comprise six active volcanoes that have deformed since first observed by satellite radar in the early 1990s. We analyse new (2015–2022) displacement time series at Alcedo, Cerro Azul, Darwin, Fernandina, Sierra Negra, and Wolf volcanoes in the context of deformation and unrest since 1992. Previous discussions of volcano deformation have focused on eruptions, major intrusive episodes, and the structure of sub-volcanic systems. We discuss the full geodetic record of deformation and show that the style of eruptions, characteristics of unrest and deformation are distinctive at each volcano. These characteristic differences in deformation and unrest styles between the volcanoes have persisted for at least three decades, since the first satellite radar measurements. These consistent differences in shallow magma storage and eruptive dynamics reflect the influence of “top-down” factors and evolutionary stage, providing a basis to understand volcanic unrest here, and to inform monitoring strategies.</p> 2024-04-23T00:00:00+00:00 Copyright (c) 2024 Eoin Reddin, Susanna Ebmeier, Marco Bagnardi, Andrew F. Bell, Pedro Espín Bedón https://www.jvolcanica.org/ojs/index.php/volcanica/article/view/234 Video camera and seismic monitoring of water bulge explosion at Strokkur Geyser, Iceland 2023-08-20T07:10:24+00:00 Eva P. S. Eibl eva.eibl@uni-potsdam.de Sandeep Karmacharya sandeep.karmacharya@uni-potsdam.de Alina V. Shevchenko alina.shevchenko@gfz-potsdam.de Thomas R. Walter twalter@gfz-potsdam.de Gylfi Páll Hersir gylfi.pall@outlook.com <p>Eruptions of volcanoes and geysers share many fundamental similarities: for example, they are manifestations of Earth’s geothermal energy, involving the pressure-driven expulsion of fluids from the Earth’s interior. However, while volcanoes can produce spectacular lava bubbles that burst, water bubbles are rarely observed on the surface of geysers. It is still unclear why some of these low-viscosity geyser systems produce none, while others produce them regularly. There is no quantification of the size, speed, and height of these bubbles at geysers, which is the gap we fill here. Strokkur creates a water bulge in its surface pool (bulge stage). When the bulge bursts, water is ejected into the air (jet stage). The steam then continues to rise buoyantly and drift away (drift stage). Here we study the evolution of the three stages using records from video camera campaigns and a local seismic network. We find that larger bulges are associated with larger ascent velocities and cause larger jet heights. As energy is channeled into a high jet, small seismic ground motions are recorded. The bulge formation itself is barely visible seismically. Our work suggests that the 0.74±0.27 s-long bulge stage can be used as a first-order proxy for predicting eruption height. This study might also be relevant for understanding fluid dynamics in volcanic systems.</p> 2024-05-08T00:00:00+00:00 Copyright (c) 2024 Eva P. S. Eibl, Sandeep Karmacharya, Alina V. Shevchenko, Thomas R. Walter, Gylfi Páll Hersir https://www.jvolcanica.org/ojs/index.php/volcanica/article/view/272 The Moinui Flow on Mauna Loa: transport and deposition of an olivine crystal cargo in a compound basaltic lava flow 2024-03-15T13:47:56+00:00 Stephen Barnes steve.barnes@csiro.au Thorvaldur Thordarson torvth@hi.is Robin E.T. Hill kalapana@westnet.com.au Caroline S. Perring caroline.s.perring@bhp.com Sarah E. Dowling kalapana@westnet.com.au Belinda Godel belinda.godel@csiro.au <p>The Moinui lava flow on the west flank of Mauna Loa, Hawai`i, is a 32-km-long pāhoehoe basalt flow, between 760 and 1500 years old, characterised by the presence of two generations of olivine: 2–5-mm-sized glomerocrystic clusters of equant polyhedral grains, and dendritic plates. Both generations are distributed throughout the flow field from the vent at 3400 m above sea level to the ocean. We mapped roadcut outcrops in detail to investigate the internal geometry and emplacement mechanisms of the flow, and sampled these outcrops to collect quantitative textural data on the two olivine populations in 2D and 3D, with a view to understanding emplacement processes in general, and the factors controlling the growth, transport, and deposition of phenocryst olivine in particular. Roadcut outcrops reveal complex geometries of interconnected tube-fed sheet lobes, with the main control being pre-existing topography: drained tubes with flanking sheet lobes were developed on the seaward slope of the volcano, whereas tumuli were developed on the flat coastal plain topography. The internal architecture of the flow field is consistent with current hypotheses of emplacement by breakout and inflation of flow lobes from tube-fed internal pathways. Concentrations of up to 30% olivine represent settling of the larger size-fraction of the transported load, with no evidence for superimposed effects of flow differentiation.Implied effective viscosities were around 1000 Pa s. The glomerocrystic population was inherited as pre-existing crystal clusters derived from a sub-volcanic chamber, rather than by synneusis (random collision and aggregation) post-eruption, whereas the plate population was probably generated by a burst of nucleation related to degassing and supercooling during the vent eruption. Other than this, there is no evidence for substantial growth of the transported olivines during flow.</p> 2024-05-13T00:00:00+00:00 Copyright (c) 2024 Steve Barnes, Thor Thordarson, Robin E.T. Hill, Caroline S. Perring, Sarah E. Dowling, Belinda Godel https://www.jvolcanica.org/ojs/index.php/volcanica/article/view/258 Temporal variations in storage conditions of the post-collapse rhyolites, Valles Caldera, New Mexico (USA) 2024-03-07T22:43:13+00:00 Magdalen Grismer magdalen.grismer@student.nmt.edu Laura Waters laura.waters@nmt.edu <p>We present a petrologic study of the post-collapse rhyolites from Valles Caldera (New Mexico, USA) to evaluate changes in magmatic storage conditions following the eruption of the Upper Bandelier Tuff (UBT). We assess likely phenocrysts through textures, comparison with experiments, and <code>rhyolite-MELTS</code> outputs, and apply thermobarometers, oxygen barometers, and hygrometers to these minerals. The post-collapse rhyolites have average pre-eruptive temperatures ranging from 742–824 °C, average pre-eruptive oxygen fugacities ranging from –0.1 to +1.3 ΔNNO, and average pre-eruptive H2O contents ranging from 4.4–6.0 wt% H2O. Average storage pressures range from 130–196 MPa for all rhyolites except the youngest, which has a range of 157–376 MPa. The post-collapse rhyolites are more oxidizing than the UBT and have similar pre-eruptive pressures. The change in oxidation state between the rhyolites and UBT, despite similar storage pressures, can be explained if the UBT is generated from a unique, reduced source but accumulated at depths similar to the post-collapse rhyolites.</p> 2024-06-06T00:00:00+00:00 Copyright (c) 2024 Magdalen Grismer, Laura Waters https://www.jvolcanica.org/ojs/index.php/volcanica/article/view/204 Magmatic Memories: Eldfell, 1973 2024-01-21T16:20:07+00:00 Rhian Meara r.h.meara@swansea.ac.uk Arnar Árnason arnar.arnason@abdn.ac.uk Osian Elias o.h.elias@swansea.ac.uk Helga Hallbergsdóttir helgahal@live.com Sigurjón Hafsteinsson sbh@hi.is <p>2023 marked the 50<sup>th</sup> anniversary of the 1973 Eldfell eruption on the island of Heimaey, Iceland. The eruption began unexpectedly at 1:50 a.m. on the 23rd of January 1973, creating a need to evacuate all 5300 residents to the Icelandic mainland by fishing fleet. The eruption is synonymous with the islanders’ fight to save their town by spraying cold seawater onto the advancing lava flows. Previous research has focussed on the physical volcanology and igneous petrology of the eruption and the wider Vestmannaeyjar Volcanic System; however, very little research has focussed on the social impacts of the eruption. Fieldwork identified how the 1973 eruption is remembered and commemorated by the residents of Heimaey both in public and private settings. Over 50 memorials are discussed, including artworks, sculptures, museum exhibitions, in-person events, and online digital repositories that highlight connections to the eruption itself and to life before the eruption. Interviews and surveys with the local community draw attention to the ongoing impacts of the eruption—for example, traumatic responses to hazard events such as the Eyjafjallajökull eruption in 2010. A predominantly positive community narrative of the event has persisted for several decades. The narrative depends on the belief that no deaths were caused by the eruption, the successful rebuilding and recovery of the town, and the resilience of the residents. The last ten years, however, have seen a change in how the community discuss their experiences of the eruption, with a new focus on the loneliness, bullying, isolation, danger, and trauma experienced during the event.</p> <h2><strong>Ágrip</strong></h2> <p>Árið 2023 voru 50 ár liðin frá Eldfellsgosinu 1973 á Heimaey. Eldgosið hófst óvænt klukkan 01.50 þann 23. janúar 1973 og þurfti að flytja 5.300 íbúana til Íslands með fiskiskipaflota. Eldgosið er samheiti við baráttu eyjarskeggja við að bjarga bænum sínum með því að úða köldum sjó á hraunið. Fyrri rannsóknir hafa beinst að eðlisfræðilegri eldfjallafræði og bergfræði gossins og víðara eldfjallakerfi Vestmannaeyja, hins vegar hafa mjög litlar rannsóknir beinst að félagslegum áhrifum gossins. Vettvangsvinna leiddi í ljós hvernig eldgosið 1973 er minnst og minnst af íbúum Heimaeyjar bæði í opinberu umhverfi og einkaumhverfi. Fjallað er um yfir 50 minnisvarða, þar á meðal listaverk, skúlptúra, safnsýningar, persónulega viðburði og stafrænar geymslur á netinu sem draga fram tengingar við eldgosið sjálft og lífið fyrir gos. Í viðtölum og könnunum við nærsamfélagið er vakin athygli á viðvarandi áhrifum eldgossins, til dæmis áfallaviðbrögðum við hættulegum atburðum nútímans eins og Eyjafjallajökulsgosinu 2010. Aðallega jákvæð samfélagsfrásögn af atburðinum hefur verið viðvarandi í nokkra áratugi. Frásögnin byggist á þeirri trú að engin dauðsföll hafi orðið af völdum eldgossins, árangursríkri endurreisn og endurheimt bæjarins og seiglu íbúanna. Síðustu tíu ár hafa hins vegar orðið róttækar breytingar á því hvernig samfélagið fjallar um upplifun sína af eldgosinu, með nýrri áherslu á einmanaleika, einelti, einangrun, hættu og áföll sem urðu fyrir atburðinum.</p> 2024-06-19T00:00:00+00:00 Copyright (c) 2024 Rhian Hedd Meara, Arnar Árnason, Osian Harri Elias, Helga Hallbergsdóttir, Sigurjón B Hafsteinsson https://www.jvolcanica.org/ojs/index.php/volcanica/article/view/273 Near-real-time ash cloud height estimation based on GOES-16 satellite imagery 2024-01-08T11:49:28+00:00 Anais Vásconez Müller avasconez@igepn.edu.ec Benjamin Bernard bbernard@igepn.edu.ec Francisco J. Vasconez fjvasconez@igepn.edu.ec <p>Timely acquisition of ash cloud heights is crucial for aviation safety and forecasting volcanic ash dispersion and fallout. Since visual observations are not always available, we assess the suitability of retrieving ash cloud heights from brightness temperature and plume direction observed in GOES-16 satellite imagery, <code>VOLCAT</code> solutions, and Washington-VAAC advisories during the 2022–2023 eruption of Cotopaxi volcano, Ecuador. We find that these satellite-derived height estimates consistently yield lower values than visual cameras. While the plume direction method and Washington-VAAC advisories produce the closest approximations, they also exhibit significant deviations. Remarkably, the brightness temperature method, despite producing the lowest height values, shows the best linear regression with visual observations. Near-real-time retrieval of ash cloud height from GOES-16 imagery is a promising alternative to direct visual observation, particularly at night, in adverse weather, or for remote volcanoes, especially if improvements, such as incorporating high-resolution local meteorological models, are introduced.</p> 2024-06-21T00:00:00+00:00 Copyright (c) 2024 Anais Vásconez Müller, Benjamin Bernard, Francisco J. Vasconez https://www.jvolcanica.org/ojs/index.php/volcanica/article/view/227 MinDet1: A deep learning-enabled approach for plagioclase textural studies 2024-01-17T01:23:01+00:00 Norbert Toth nt398@cam.ac.uk John Maclennan jcm1004@cam.ac.uk <p>Quantitative textural attributes, such as crystal size distributions or aspect ratios, provide important constraints on the thermal history of rocks. They facilitate the investigation of crystal nucleation, growth, and mixing as well as cooling rate. However, they require large volumes of crystal segmentations and measurements often obtained with manual methods. Here, a deep learning-based technique—instance segmentation—is proposed to automate the pixel-by-pixel detection of plagioclase crystals in thin-section images. Using predictions from a re-trained model, the physical properties of the detected crystals (size and aspect ratio) are rapidly generated to provide textural insights. These are validated against published results from manual approaches to demonstrate the accuracy of the method. The power and efficiency of this approach is showcased by analysing an entire sample suite, segmenting over 48,000 crystals in a matter of days. The approach is available as <code>MinDet1</code> software for users with moderate expertise in <code>Python</code>. Widespread use of <code>MinDet</code> may facilitate significant developments in igneous petrography and related fields.</p> 2024-03-06T00:00:00+00:00 Copyright (c) 2024 Norbert Toth, John Maclennan https://www.jvolcanica.org/ojs/index.php/volcanica/article/view/252 DiadFit: An open-source Python3 tool for peak fitting of Raman data from silicate melts and CO2 fluids 2024-04-25T04:06:58+00:00 Penny E. Wieser penny_wieser@berkeley.edu Charlotte DeVitre cdevitre@berkeley.edu <p>We present <code>DiadFit</code>—an open-source Python3 tool for efficient processing of Raman spectroscopy data collected from fluid inclusions, melt inclusions and silicate melts. <code>DiadFit</code> is optimized to fit the characteristic peaks from CO<sub>2</sub> fluids (Fermi diads, hot bands, <sup>13</sup>C), gas species such as SO<sub>2</sub>, N<sub>2</sub>, solid precipitates (e.g. carbonates), and Ne emission lines with easily tweakable background positions and peak shapes. <code>DiadFit</code>'s peak fitting functions are used as part of a number of workflows optimized for quantification of CO<sub>2</sub> in melt inclusion vapour bubbles and fluid inclusions. <code>DiadFit</code> can also convert between temperature, pressure and density using various CO<sub>2</sub> and CO<sub>2</sub>-H<sub>2</sub>O equations of state (EOS), allowing calculation of fluid inclusion pressures (and depths in the crust), conversion of homogenization temperatures from microthermometry to CO<sub>2</sub> density, and propagation of uncertainties associated with EOS calculations using Monte Carlo methods. There are also functions to quantify the area ratio of the silicate vs. H<sub>2</sub>O region of spectra collected on silicate glasses to determine H<sub>2</sub>O contents in glasses and melt inclusions. Documentation and worked examples are available (<a href="https://bit.ly/DiadFitRTD">https://bit.ly/DiadFitRTD</a>, <a href="https://bit.ly/DiadFitYouTube"> https://bit.ly/DiadFitYouTube</a>).</p> 2024-06-14T00:00:00+00:00 Copyright (c) 2024 Penny E. Wieser, Charlotte DeVitre https://www.jvolcanica.org/ojs/index.php/volcanica/article/view/245 The utility of TerraSAR-X, TanDEM-X, and PAZ for studying global volcanic activity: Successes, challenges, and future prospects 2023-11-12T15:45:26+00:00 Federico Galetto fg253@cornell.edu Edna Dualeh edna.dualeh@bristol.ac.uk Francisco Delgado fdelgado@uchile.cl Matthew Pritchard pritchard@cornell.edu Michael Poland mpoland@usgs.gov Susanna Ebmeier s.k.ebmeier@leeds.ac.uk Tara Shreve tlshreve@alaska.edu Juliet Biggs Juliet.Biggs@bristol.ac.uk Ian Hamling i.hamling@gns.cri.nz Christelle Wauthier cuw25@psu.edu Judit Gonzalez Santana jmg6885@psu.edu Jean-Luc Froger jean-luc.froger@univ-st-etienne.fr Mark Bemelmans tz20896@bristol.ac.uk <p>TerraSAR-X (TSX), TanDEM-X (TDX), and PAZ Synthetic Aperture Radar data have been used at over 120 volcanoes to assess surface characteristics and change over time. We examine previous work, adding additional examples to understand where and when these data are most useful for volcanology. We focus on volcanoes as part of the Committee on Earth Observation Satellites (CEOS) Volcano Demonstrator Project. TSX/TDX/PAZ data provide a valuable means of detecting small surface changes from amplitude images and topographic changes from bistatic TSX/TDX data. For short temporal and perpendicular baselines, TDX/TSX/PAZ can also provide useful deformation data, even in presence of vegetation. No global background mission currently acquires TSX/TDX/PAZ data at volcanoes: 70 % high spatial resolution data, limiting their suitability for studying pre-eruptive unrest. Coordinated targeting by SAR constellations of priority volcanoes would provide data and insights valuable for forecasting eruptions and associated hazards.</p> 2024-06-04T00:00:00+00:00 Copyright (c) 2024 Federico Galetto, Edna Dualeh, Francisco Delgado, Matthew Pritchard, Michael Poland, Susanna Ebmeier, Tara Shreve, Juliet Biggs, Ian Hamling, Christelle Wauthier, Judit Gonzalez Santana, Jean-Luc Froger, Mark Bemelmans