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Santorini je vulkanski otok, ki se nahaja na jugu Egejskega morja. Ta ima za sabo pestro zgodovino, med katero se je spremenil v veliko kaldero. Na otoku lahko opazimo bogato zbirko različnih vulkanskih kamnin. Z makroskopskim opazovanjem in mikroskopsko analizo z uporabo presevnega optičnega mikroskopa smo opravili pregled vzorcev, odvzetih z otoka Nea Kameni, ter lokacij Kokkari in Vlychada. Nekaj vzorcev smo naknadno pregledali s pomočjo vrstičnega elektronskega mikroskopa in na podlagi dobljenih rezultatov določili kemično sestavo izbranih mineralnih zrn v vzorcu. Z rentgensko praškovno difrakcijsko analizo smo določili mineralno sestavo in amorfno fazo posameznih vzorcev. Na podlagi geokemične analize smo kamnine razdelili v skupine na podlagi razmerja med vsebnostjo kremenice in deležem Zr/TiO2. Z optično mikroskopijo smo v vseh vzorcih določili hipohialinsko, afanitsko in oligofirsko strukturo. Vsi vzorci vsebujejo plagioklaze in piroksene, nekateri tudi olivine in nepresevne minerale. V vzorcih Nea Kameni in Kokkari se med plagioklazi pojavljata labradorit in bytownit, med pirokseni pa avgit, redkeje enstatit. Nekaj je olivinov, ki so bogatejši z magnezijem. Med plagioklazi v vzorcu Vlychada prevladuje andezin, med pirokseni je prisoten le enstatit. Rezultati geokemične analize so pokazali, da na otoku Nea Kameni prevladujejo rioliti ob manjši prisotnosti andezitov. Vzorci s Kokkari lokacije so pretežno rdeče-rjave barve in pripadajo andezitom in trahi-andezitom. Odvzete bele in lahke kamnine z bele plaže Vlychada smo uvrstili v skupino trahitov. Vulkanske kamnine z lokacije Nea Kameni smo pripisali najmlajši vulkanski dejavnosti, pri kateri je otok tudi nastal. Kamnine z bele plaže Vlychada so nastale med glavnima plinijskima izbruhoma, ob koncu prvega vulkanskega cikla. Andezitne kamnine z rdeče plaže Kokkari so kvartarne starosti in so nastale kot posledica začetka vulkanske dejavnosti na Santoriniju. Gre za pepelaste stožce, ki so nastali ob eksplozivnem izbruhu velikih vulkanskih bomb. Santorini is a volcanic island located in the south of the Aegean Sea. It has a varied history behind it, during which it turned into a large caldera. A rich collection of various volcanic rocks can be seen on the island. With macroscopic observation and microscopic analysis using a scanning optical microscope, we performed an examination of the samples taken from the island of Nea Kameni and the locations of Kokkari and Vlychada. Some samples were subsequently examined with the help of a line electron microscope and, based on the obtained results, the chemical composition of the selected mineral grains in the sample was determined. X-ray powder diffraction analysis was used to determine the mineral composition and amorphous phase of individual samples. Based on the geochemical analysis, the rocks were divided into groups based on the ratio between the quartz content and the Zr/TiO2 ratio. Optical microscopy was used to determine the hypohyaline, aphanitic and oligophyric structure in all samples. All samples contain plagioclase and pyroxenes, some also contain olivine and non-replaceable minerals. In the samples from Nea Kameni and Kokkari, labradorite and bytownite occur among plagioclase, and augite and less commonly enstatite among pyroxenes. There are some olivines that are richer in magnesium. Among the plagioclases in the Vlychada sample, andesine dominates, while only enstatite is present among the pyroxenes. The results of the geochemical analysis showed that the island of Nea Kameni is dominated by rhyolites with a minor presence of andesites. The samples from the Kokkari location are predominantly red-brown in color and belong to andesite and trachy-andesite. The white and light rocks taken from the white beach of Vlychada were classified as trachytes. Volcanic rocks from the Nea Kameni location were attributed to the youngest volcanic activity, during which the island was formed. The rocks from the white beach of Vlychada were formed during the main Plinian eruptions, at the end of the first volcanic cycle. The andesite rocks of Kokkari Red Beach are of Quaternary age and were formed as a result of the onset of volcanic activity on Santorini. These are cinder cones that were formed during the explosive eruption of large volcanic bombs.

Understanding the contribution of the Antarctic Ice Sheet (AIS) to past and future sea-level rise has emerged as a scientific priority over the last four decades. Whilst our knowledge of ice-dynamical changes occurring as a result of current anthropogenic forcing has improved considerably since the start of the satellite era, significantly less is known about the evolution of the AIS during the pre-industrial Holocene (the last ~11.7 thousand years; ka). Quantifying these changes is crucial, however, as this time period corresponds to a time when the ice sheet was retreating from its maximal extent at the Last Glacial Maximum (LGM; ~20 ka) and environmental conditions were similar to today. Therefore, improving our understanding of this period may provide a long-term context to the decadal changes observed in recent times and how these may evolve in the future. Whilst point-based geochronological measurements of ice and sediment cores, or surface exposure dating, can be used to assess past ice-sheet changes over the AIS, it remains unclear how representative they are of a wider region. A complementary and spatially extensive resource across the ice sheet are Internal Reflecting Horizons (IRHs) as imaged by Radio-Echo Sounding (RES) techniques, which provide a cumulative record of accumulation, basal melt and ice dynamics that, if dated precisely at ice cores, can be used to inform numerical ice-sheet models projecting past and future changes on large spatial scales. The aim of this thesis is therefore to develop and extend age-depth models from IRHs across the AIS to assess the past stability of the ice sheet. In this thesis, an age-depth model of Pine Island Glacier spanning the LGM and Holocene periods is derived from spatially extensive IRHs. The connection between RES profiles and the WAIS Divide ice core enables the direct dating of the IRHs, and reveals that they match large peaks in sulphate concentrations which are unparalleled in the 68,000 year-old record, thus suggesting that the cause of these IRHs is from past explosive volcanic eruptions. By connecting this IRH stratigraphy with a previously developed age-depth model across the Institute and Möller Ice Streams (IMIS), I show that a precisely dated age-depth model now exists over 20% of the West Antarctic Ice Sheet (WAIS). One of these IRHs, precisely dated at ~4.7 ka, is then used as input into a one-dimensional ice-flow model to estimate past accumulation rates during the mid-Holocene over the catchments encompassing Pine Island Glacier, Thwaites Glacier, and IMIS, together representing 30% of the WAIS. The inferred mid-Holocene accumulation estimates are then compared with modern rates derived from climate models and observational measurements to show that accumulation rates were 18% greater during the last five millennia compared to the present over the Amundsen-Weddell-Ross Divide. These results match previous findings from isolated ice-core measurements and spatially targeted studies over the divide, and correspond to periods of grounding line retreat and readvance during the Holocene over the WAIS. Together, these show the potential for extracting further IRH information from other sectors of the AIS in order to build an age-depth model of the ice sheet. However, the underlying RES data necessary for this work were, until recently, relatively inaccessible to the wider scientific community, thus restricting the extraction and interpretation of age-depth models across the AIS. This motivated the release of ~300,000 line-km of RES profiles acquired by the British Antarctic Survey between 2004 and 2020. In addition to standardising and releasing these data, this thesis shows that large sections of continuous englacial layering exist widely across both East and West Antarctica, suggesting that, together with previously developed age-depth models of both regions and nearby ice-core stratigraphies, these newly released RES datasets will be critical in our aim to build an ice-sheet wide age-depth model of Antarctica, as motivated by the AntArchitecture Initiative. Together, the findings from this thesis reveal the spatially extensive nature of IRHs across West and East Antarctica and demonstrate how these can be used to infer past ice-sheet changes. This thesis also highlights the need to extract further age-depth models, particularly across East Antarctica, in order to provide important boundary conditions such as past accumulation rates and ice-elevation change which can be used by numerical ice-sheet models to help improve predictions of past and future ice-sheet change and ensuing sea-level rise contributions.

The surface expression of upper crustal deformation varies widely based on geologic settings. Normal faults within an intra-arc basin, strike-slip faulting within a wide shear zone, and creeping fault behavior all manifest differently and require a variety of techniques for analysis. In this dissertation I studied three different actively deforming regions across a variety of geologic settings. First, I explored the drivers of extension within the La Pine graben in the Oregon Cascades. I mapped >20 new Quaternary faults and conducted paleoseismic trenching, where I found evidence for a mid-late Holocene earthquake on the Twin Lakes maar fault. I suggest that tectonics and not volcanism is responsible for the most recent deformation in the region based on fault geometries and earthquake timings, although more research is needed to tease out finer temporal and genetic relationships between tectonics and volcanism regionally. Second, I investigated the rupture pattern and earthquake history of the Calico fault system in the Eastern California Shear Zone. We mapped ~18 km of continuous rupture, with a mean offset of 2.3 m based on 39 field measurements. We also found evidence for two earthquakes, 0.5 - 1.7 ka and 5.5 - 6.6 ka through paleoseismic trenching. We develop a number of different multifault rupture scenarios using our rupture mapping and rupture scaling relationships to conduct Coulomb stress change modeling for the most recent earthquake on the Calico fault system. We find that the most recent event places regions adjacent to the fault in a stress shadow and may have both delayed the historic Landers and Hector Mine ruptures and prevented triggering of the Calico fault system during those events. Last, I studied the spatial distribution of the southern transition zone of the creeping section of the San Andreas fault at Parkfield, CA to determine if it shifted in response to the M6 2004 Parkfield earthquake. I used an Iterative Closest Point algorithm to find the displacement between two lidar datasets acquired 13 years apart. I compared creep rates measured before the 2004 earthquake to creep rates calculated from my lidar displacement results and found that there is not a discernible change in the overall pattern or distribution of creep as a response to the 2004 earthquake. Peaks within the lidar displacement results indicate complexity in the geometry of fault locking. Doctor of Philosophy Fault behavior varies widely across different regions, depending on the type of fault and local geology. In this dissertation I examine three regions with different mechanisms controlling deformation within them. First, I study the relationship between volcanic and tectonic induced faulting in the La Pine graben in the Oregon Cascades. While volcanoes and tectonics can both produce faults within a region, the surface expression of those faults changes depending on the underlying driver. I map > 20 new faults in the La Pine graben. I also conduct paleoseismic trenching on one of the newly identified faults, the Twin Lakes maar fault, and find that its most recent rupture occurred < 7.6 ka. I conclude that tectonism is the dominant driver of faulting within the La Pine graben based on the fault geometries and timing between identified regional earthquakes and volcanism. Second, I explore recent rupture on the Calico fault system in the Eastern California Shear Zone, which is a wide region across eastern California where deformation is distributed among many faults. Faulting in this region is complex, with some earthquakes occurring on multiple connected faults. I conducted a paleoseismic survey to determine the timing of the most recent earthquake(s) on the Calico fault system. This trenching effort found evidence for 1-2 earthquakes, the most recent occurring 0.5 – 1.7 ka. I use the rupture mapping and earthquake timing to develop a number of various rupture scenarios. I use these scenarios as inputs for computer modeling to explore the regional stress changes from these events and find that they reduce the overall stress in the area, elongating the amount of time between regional earthquakes. Last, I examine how creeping fault behavior on the San Andreas fault near Parkfield, CA changes as a response to an earthquake. Creeping behavior is where the two sides of a fault are continuously moving past one another. I examine the spatial distribution of where the San Andreas fault transitions from creeping to locked behavior by differencing two high-resolution lidar topographic datasets taken after the M6 2004 Parkfield earthquake. I compare my displacement results to pre-2004 datasets and conclude that the transition zone did not appreciably change as a result of the earthquake.

Alunogen, Al2(SO4)3·17H2O, occurs as an efflorescent in acid mine drainage, low-temperature fumarolic or pseudofumarolic (such as with coal fires) terrestrial environments. It is considered to be one of the main Al-sulphates of Martian soils, demanding comprehensive crystal-chemical data of natural terrestrial samples. Structural studies of natural alunogen were carried out in the 1970s without localization of H atoms and have not been previously performed for samples from geothermal fields, despite the fact that these environments are considered to be proxies of the Martian conditions. The studied alunogen sample comes from Verkhne–Koshelevsky geothermal field (Koshelev volcano, Kamchatka, Russia). Its chemical formula is somewhat dehydrated, Al2(SO4)3·15.8H2O. The crystal structure was solved and refined to R1 = 0.068 based on 5112 unique observed reflections with I > 2σ(I). Alunogen crystalizes in the P-1 space group, a = 7.4194(3), b = 26.9763(9), c = 6.0549(2) Å, α = 90.043(3), β = 97.703(3), γ = 91.673(3) °, V = 1200.41(7) Å3, Z = 2. The crystal structure consists of isolated SO4 tetrahedra, Al(H2O)6 octahedra and H2O molecules connected by hydrogen bonds. The structure refinement includes Al, S and O positions that are similar to previous structure determinations and thirty-four H positions localized for the natural sample first. The study also shows the absence of isomorphic substitutions in the composition of alunogen despite the iron-enriched environment of mineral crystallization. The variability of the alunogen crystal structure is reflected in the number of the “zeolite” H2O molecules and their splitting. The structural complexity of alunogen and its modifications ranges from 333–346 bits/cell for models with non-localized H atoms to 783–828 bits/cell for models with localized H atoms. The higher values correspond to the higher hydration state of alunogen.

The dryness of the stratosphere is the result of air entering through the cold tropical tropopause layer (TTL). However, our understanding of the moisture flux partitioning into water vapor and frozen hydrometeors is incomplete. This raises concerns regarding the ability of General Circulation Models to accurately predict changes in stratospheric water vapor following perturbations in the radiative budget due to volcanic aerosol or stratospheric geoengineering. We present the first results using a global storm‐resolving model investigating the sensitivity of moisture fluxes within the TTL to an additional heating source. We address the question how the partitioning of moisture fluxes into water vapor and frozen hydrometeors changes under perturbations. The analysis reveals the resilience of the TTL, keeping the flux partitioning constant even at an average cold‐point warming exceeding 8 K. In the control and perturbed simulations, water vapor contributes around 80% of the moisture entering the stratosphere., Plain Language Summary: The stratosphere is a dry region since moisture entering it from below has to pass the cold‐point, a temperature minimum between troposphere and stratosphere. The low temperatures lead to ice formation and sedimentation of moisture. Frozen moisture within clouds rising above the cold‐point tropopause can pass this temperature barrier and be injected into the stratosphere, where temperatures increase again, promoting the melting and sublimation of ice crystals. However, little is known about the sensitivity of the split of moisture entering the stratosphere into frozen and non‐frozen moisture, especially under external influences, like heating by volcanic aerosol or stratospheric geoengineering efforts. Convective parameterizations in conventional simulations can lead to biases. The emerging km‐scale simulations, which explicitly resolve the physical processes, offer the unique possibility to study moisture fluxes under external forcing while circumventing the downsides of parameterizations. Here, the sensitivity of the moisture flux partitioning into non‐frozen and frozen components to an additional heating source is studied for the first time in global storm‐resolving simulations. The analysis reveals an unaltered flux partitioning even at an average cold‐point warming exceeding 8 K. In the control and perturbed simulations, water vapor contributes around 80% of the moisture entering the stratosphere., Key Points:Water vapor dominates the stratospheric moisture budget with a contribution of around 80% in global storm‐resolving simulation. The partitioning of stratospheric moisture fluxes into vapor and frozen hydrometeors remains stable under large temperature perturbations., Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659, Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347, Fueglistaler Group

This research was funded by the International Civil Aviation Organization (ICAO) under the Joint Finance Agreement with the Icelandic Meteorological Office, for working paper JS.212.WP.2054, The Icelandic Meteorological Office maintains a national network of webcams designed and built in house for environmental monitoring. During the 2021 Fagradalsfjall eruption these cameras, along with a temporary near-field network of commercial cameras installed by the Department of Civil Protection and Emergency Management, were used to estimate the height of the SO2 plume and lava fountain. Here we present the webcam designs, the techniques used to calibrate them, and the messaging system and web interface that allow near real time measurements to be made from the images. With this system we were able to make estimates of heights with an accuracy on the order of tens to a few hundreds of meters with a lag typically of five to ten minutes at up to ten minute intervals when weather conditions were favorable. The plume heights were then used to constrain the performance of the SO2 dispersion model used for air quality forecasts while fountain heights were used to delineate danger zones where visitors at the eruption site were in danger of being hit by ballistic clasts., Icelandic Meteorological Office, International Civil Aviation Organization

Seismic arrays provide tools for the localization of events without clear phases or events outside the network, where the station coverage prohibits classical localization techniques. Beam forming allows the determination of the direction (back azimuth) and horizontal (apparent) velocity of an incoming wavefront. Here we combine multiple arrays to retrieve event epicentres from the area of intersecting beams without the need to specify a velocity model. The analysis is performed in the time domain, which allows selecting a relatively narrow time window around the phase of interest while preserving frequency bandwidth. This technique is applied to earthquakes and hybrid events in the region of Fogo and Brava, two islands of the southern chain of the Cape Verde archipelago. The results show that the earthquakes mainly originate near Brava, whereas the hybrid events are located on Fogo. By multiple-event beam stacking we are able to further constrain the epicentral locations of the hybrid events in the northwestern part of the collapse scar of Fogo. In previous studies, these events were attributed to shallow hydrothermal processes. However, we obtain relatively high apparent velocities at the arrays, pointing to either deeper sources or complex ray paths. For a better understanding of possible errors of the multi-array analysis, we also compare slowness values obtained from the array analysis with those derived from earthquake locations from classical (local network) localizations. In general, the results agree well. Nevertheless, some systematic deviations of the array-derived back-azimuth and slowness values occur that can be quantified for certain event locations.

To understand a field of volcanic activity, a survey on the Earth’s subsurface structure is helpful. In particular, a magnetotelluric survey can image the subsurface structure necessary for volcanic disaster prevention because it is sensitive to high-temperature areas and areas where fluid and clay minerals exist. In 3-D magnetotelluric inversion using the data observed near volcanoes and the coastline, the topography and sea around the survey area need to be considered. Therefore, constructing a mesh of the analysis area by automatically using topography and bathymetry data is necessary. Additionally, the estimated subsurface structure should be compared to the sources of variation estimated from other physical observations, such as earthquakes, ground deformation, and changes in the geomagnetic total field, for interpretation. This study introduces a simple and easy-to-operate graphical pre- and post-processor developed to support the resistivity structure analysis of a volcano and the nearby coastline. In the developed software, the pre-process indicates the mesh construction, and the post-process indicates result derivation, file construction for the sensitivity tests, and file exportation to compare the inversion results with other measured quantities. This pre- and post-process can be performed easily on the same window of the software.

We describe results from coastal radar systems that observed anomalous current flows generated by the volcanic eruption in the Tongan archipelago on 15 January 2022 UTC, reporting the first radar detection of a volcanic tsunami. The eruption caused small tsunamis along the western U.S. Coast, generating some damage in a few harbors. The highest tsunami signal in U.S. tide gauge data from the California coast occurred at Arena Cove, with significant heights detected at Port San Luis and Crescent City. We analyze correlated wave orbital velocity detections by High Frequency (HF) radars along the coast between Gerstle Cove and Santa Barbara. Signals observed by the radars indicate that the event had two phases, each with its own distinct genesis: an initial weak surface disturbance, most likely generated by the wave of atmospheric pressure that moved outward from the blast source at just below the speed of sound, followed by a stronger disturbance that arrived approximately 3.5 h later, matching the arrival time for a wave moving entirely through the water from the volcano to the U.S. West Coast. We conclude that this phase consists of a conventional water wave tsunami and weaker waves generated by the pulse. We also report the detection of a small pulse-generated event off the west coast of Florida. Radar observations are compared with water level measurements at nearby tide gauges and a DART buoy, and with observations of barometric pressure. We point out that a Proudman near-resonance at the Tonga Trench is unlikely to explain the second phase observations. Comparison with tide gauge signals at San Francisco, generated by the Krakatoa eruption in 1883, support our conclusions.

This research contributes to environmental microbiology in deciphering and understanding the complex terrestrial and aquatic system, particularly, the microbial evaluation of extreme ecosystems. In such environments, highly adapted organisms inhabit the most adverse landscapes. Such adaptation is highly dynamic and complex, and often more than one evolutionary process is involved. For example, in glaciers, temperatures below 0°C, high ultraviolet radiation and scarcity of energetic sources are challenging factors that microorganisms in this type of habitat must successfully cope with. Many of these types of microorganisms can reduce energy consumption and express enzymes with high catalytic activity that can be applied to industry. This proximal study covers both the technology employed to achieve the objectives, as well as the most important aspect about the structure and identification of the bacterial communities present in the two locations in the Ecuadorian Andes, the Cayambe glacier and the Sumaco volcano, not reported until now. Esta Investigación aporta a la Microbiología ambiental en descifrar y comprender el complejo sistema terrestre y acuático, particularmente, la evaluación microbiana de ecosistemas extremos. En este tipo de ambientes, los organismos altamente adaptados habitan los paisajes más adversos. Dicha adaptación es muy dinámica y compleja, y a menudo más de un frente evolutivo está involucrado en este proceso. Por ejemplo, en los glaciares, las temperaturas por debajo de 0ºC, la alta radiación ultravioleta y la escasez de fuentes energéticas, son factores desafiantes que los microorganismos en este tipo de hábitats deben enfrentar con éxito. Se han descubierto diferentes rutas para superar estas fuerzas evolutivas. Muchos de este tipo de microorganismos son capaces de reducir el consumo de energía y de expresar enzimas de alta actividad catalítica que pueden aplicarse en la industria. Este estudio cubrió tanto la tecnología empleada para lograr los objetivos, así como el aspecto más importante acerca de la estructura e identificación proximal de las comunidades bacterianas presentes en las dos ubicaciones de los Andes ecuatorianos, el glaciar Cayambe y el volcán Sumaco, no reportadas hasta la actualidad.

Ten informative panels were designed to organize an exhibition of the LAJIAL project results about the recent volcanism of El Hierro Island and the 2021 eruption in La Palma Island. The format was self-rolling panels (roll-ups) 1 m wide by 2 m high, easily transportable, and highly protective. This exhibition was entitled 'Volcanoes in motion: El Hierro and La Palma' and allows us to understand that the volcanic phenomenon is very dynamic and capable of quickly changing the forms of relief, the water network, or the land use. The presentation in all these panels always keeps the same content: an upper strip including the titles of the exhibition, the thematic block, and the panel, as well as its numbering and logos of the promoting entities; a central part with much visual information in the form of maps, figures and photos accompanied by concise and easy-to-read texts; and a lower strip with the credits of the authors and logos of their institutions. The first block of panels, 'A sea of volcanoes', deals with the generation of intraplate volcanic islands, with the example of the Canary Islands (Panel 1: The Canary Islands, that is how it all began) and the geological evolution of the island of El Hierro (Panel 2: And El Hierro was born). The second block, 'Volcanic landscapes of El Hierro', focuses on geological structures on a large scale (Panel 3: Megastructures) and a small scale (Panel 4: Structures on the ground). The third block, 'Explore your volcanic paradise', pays homage to the geological maps and the last eruption on El Hierro island. Panel 5: Walking among volcanoes shows the Gorona del Lajial eruption, a true paradise of volcanic structures but a geological puzzle solved within the framework of the LAJIAL project. Panel 6: 'The last volcano' is dedicated to the eruption of the Tagoro submarine volcano. The fourth block, 'Living among volcanoes', focuses on the islander's adaptation to the volcanic territory through the rational exploitation of groundwater (Panel 7: Water on El Hierro), volcanic materials as construction elements, or the figure of the UNESCO Geopark of El Hierro (Panel 8: What the land tells us), which brings together the geology of the island with its inhabitants, promoting the sustainable development, its agricultural techniques or knowledge of its archaeological remains. The last block of two panels, 'La Palma: the pretty island' is devoted to the geological evolution of La Palma island (Panel 9: And La Palma was born) and the 2021 eruption of Tajogaite volcano (Panel 10: The eruption of 2021) that represent the last volcanic activity in the archipelago., Project LAJIAL, Grant PGC2018-101027-B-I00 funded by MCIN/AEI/10.13039/ 501100011033 and by "ERDF A way of making Europe", by the "European Union", PhD Grant 2021 FISDU 00347, Departament de Recerca i Universitats, Generalitat de Catalunya, Research Consolidated Group GEOVOL (Universidad de Las Palmas de Gran Canaria), Research Consolidated Group GEOPAM (Generalitat de Catalunya, 2017 SGR 1494)

[ES] La erupción volcánica de la isla española de La Palma, iniciada el 19 de septiembre de 2021, ha podido ser monitorizada gracias a los satélites artificiales de observación terrestre. En este trabajo se presenta el marco teórico de esta tecnología y una catalogación de las principales misiones que incorporan el radar de apertura sintética en su carga de pago. Además, también se realiza un estudio y análisis de los datos e imágenes que dichos satélites han ofrecido de la evolución de la lava, de las deformaciones del terreno y para la cuantificación de daños durante la erupción., [EN] The volcanic eruption on the Spanish island of La Palma, which began on September 19th 2021, has been monitored thanks to artificial Earth observation satellites. This work presents the theoretical framework behind this technology and a catalogue covering the main missions carrying a synthetic aperture radar in their payload. Moreover, it is also provided with an analysis of the data these satellites offered on the quantification of damage for the evolution of the lava and the deformations of the terrain during the eruption.

soumis a JGR Atmospheres - First posted online: Fri, 8 Oct 2021; International audience; During the extended activity of Mount Etna volcano in February-April 2021, three distinct paroxysmal events took place from 21 to 26 February, which were associated with a very uncommon transport of the injected upper-tropospheric plumes towards the north. Using a synergy of observations and modelling, we characterised the emissions and three-dimensional dispersion for these three plumes, we monitor their downwind distribution and optical properties, and we estimate their radiative impacts at selected locations. With a satellite-based source inversion, we estimate the emitted sulphur dioxide (SO2) mass at an integrated value of 55 kt and plumes injections at up to 12 km altitudes, which qualifies this series as an extreme event for Mount Etna. Then, we combine Lagrangian dispersion modelling, initialised with measured temporally-resolved SO2 emission fluxes and altitudes, with satellite observations to track the dispersion of the three individual plumes. The transport towards the north allowed the height-resolved downwind monitoring of the plumes at selected observatories in France, Italy and Israel, using LiDARs and photometric aerosol observations. Volcanic-specific aerosol optical depths in the visible spectral range ranging from about 0.004 to 0.03 and local daily average shortwave radiative forcing ranging from about -0.2 to -1.2 W/m2 (at the top of atmosphere) and from about -0.2 to -3.0 W/m2 (at the surface) are found. The composition (possible presence of ash), aerosol optical depth and radiative forcing of the plume has a large inter- and intra-plume variability and thus depend strongly on the position of the sampled section of the plumes.

Nisyros Geopark, an island geopark in the Southeastern Aegean Sea, Greece, is here presented as an official candidate for the UNESCO Global Geoparks designation, featuring outstanding geological, natural and cultural characteristics tightly connected to its volcanic origin. It covers a total area of 481 km2 and includes Nisyros, an active volcano and the main island, the surrounding islets of Pachia, Strongyli, Pergousa, Kandeliousa and the marine region among them. It features 24 geosites and a network of well-established walking trails. Furthermore, there are two internationally designated Natura 2000 areas covering its entire surface and also exceptional archaeological and cultural sites, including fortresses, remnants of ancient habituations and numerous churches and monasteries. It is the only area in the broader region of the Eastern Mediterranean that hosts all these features within such a restricted area. The initial efforts of the management body of Nisyros Geopark and its scientific team to promote its unique geodiversity included the complete design, construction and launch of the official website, the mobile application “Nisyros Volcano App’’, a modern informative leaflet regarding the region of the hydrothermal craters (Lakki), a Geopark guidebook and a series of panels and signs for the geosites.

In this work, the main aim is to reduce the adhesion and wear that happened during machining of the Ti6Al4V alloy by employing volcano-like texture on the rake face of coated tool. A combination of experimental and simulative investigation was adopted. DEFORM-3D software with updated Lagrangian formulation was used for numerical simulation, and the thermo-mechanical analysis was performed using Johnson-Cook material model to predict the cutting temperature, cutting forces, chip morphology and tool wear. In cutting experiments, volcano-like textures with different area densities (10%, 20%, 30%) were fabricated by fiber laser on the rake face of cemented carbide tools close to the main cutting edge. Then, these textured tools were deposited with CrAlN coating through cathodic vacuum arc ion plating technique. Experiments in cutting Ti6Al4V alloy were carried out with the textured coated tools and non-textured coated tool under dry and wet cutting conditions. Then, the chip morphology, chip size and tool wear were investigated. The results showed that textured coated tools were superior to conventional tool. Especially in wet cutting, compared with those of non-textured coated tool, the adhesion area and the chip curling radius of the coated tool with texture area density of 20% (VCT2) were reduced by 31.2% and 49.7%, respectively. Therefore, VCT2 tool showed a better cutting performance. Finally, the mechanisms of textured coated tools under dry and wet cutting conditions were proposed.

The Westwood deposit (4.5 Moz Au) is hosted in the 2699–2695 Ma Bousquet Formation volcanic and intrusive rocks, in the eastern part of the Blake River Group, southern Abitibi greenstone belt. The Bousquet Formation is divided in two geochemically distinct members: a mafic to intermediate, tholeiitic to transitional lower member and an intermediate to felsic, transitional to calc-alkaline upper member. The Bousquet Formation is cut by the synvolcanic (2699–2696 Ma) polyphase Mooshla Intrusive Complex, which is cogenetic with the Bousquet Formation. The deposit contains three strongly deformed (D2 flattening and stretching), steeply S-dipping mineralized corridors that are stacked from north to south: Zone 2 Extension, North Corridor, and Westwood Corridor. The North and Westwood corridors are composed of Au-rich polymetallic sulfide veins and stratabound to stratiform disseminated to massive sulfide ore zones that are spatially and genetically associated with the calcalkaline, intermediate to felsic volcanic rocks of the upper Bousquet Formation. The formation of the disseminated to semimassive ore zones is interpreted as strongly controlled by the replacement of porous volcaniclastic rocks at the contact with more impermeable massive cap rocks that helped confine the upflow of mineralizing fluids. The massive sulfide lenses are spatially associated with dacitic to rhyolitic domes and are interpreted as being formed, at least in part, on the paleoseafloor. The epizonal, sulfide-quartz vein-type ore zones of the Zone 2 Extension are associated with the injection of subvolcanic, calc-alkaline felsic sills and dikes within the lower Bousquet Formation. These subvolcanic intrusive rocks, previously interpreted as lava flows, are cogenetic and coeval with the intermediate to felsic lava flows and domes of the upper Bousquet Formation. The change from fractional crystallization to assimilation- and fractional crystallization-dominated processes and transitional to calc-alkaline magmatism is interpreted to be responsible for the development of the auriferous ore-forming system. The Westwood deposit is similar to some Phanerozoic Au ± base metal-rich magmatic-hydrothermal systems, both in terms of local volcano-plutonic architecture and inferred petrogenetic context. The complex volcanic evolution of the host sequence at Westwood, combined with its proximity to a polyphase synvolcanic intrusive complex, led to the development of one of the few known large Archean subaqueous Au-rich magmatic-hydrothermal systems.

This article considers Lake Toba’s origins through global science and local folklore to examine how volcanic eruptions in the deep past are accessed, remembered, and understood. The eruption of the Toba volcano circa 73,000 years ago was theorized by some scientists as a “Super Catastrophe” that nearly extinguished the human population. At a local level, folklore of the Toba Batak peoples articulates this disaster in the form of morality tales. In these stories, nature is anthropomorphized as an act of memory to warn against the future impact of wrongful action. This article argues that both historical memories index a history of the future. While seemingly disparate, each narrative— scientific and folkloric—contains a meta-narrative on how the future has shaped our questions of the past and vice versa. In both epistemes, the writing of the distant past emerges with the writing of the future to define ethical choices for the present.

Volcanic regions are associated with increased environmental and human health risks due to elevated concentrations of potentially toxic elements (PTEs). Fogo Island, Cape Verde, experienced recent volcanic eruptions, which raised questions about local soils' potential to pose such risks. To better understand the local mineralogy and geochemistry, and environmental and probabilistic human health risks, we (i) investigate the distribution of selected PTEs in 140 soil samples covering different geologic units, (ii) determine major associations between minerals and geological units, (iii) calculate the potential ecological risk, and (iv) model human health risks based on Monte Carlo simulations. The results show that the soils overlaying the older pre-caldera units yield higher contents of secondary minerals (phyllosilicates and Fe-oxides), with relative enrichment of PTEs. The soils covering more recent units are enriched with primary minerals (feldspar and pyroxene) and show elevated concentrations of Pb. This study suggests that As, Pb, Cd and Hg pose ‘considerable’ to ‘very high’ ecological risks. Based on probabilistic health risk simulation, ingestion is identified as the dominant pathway of PTEs exposure. Metal(oid)s are unlikely to cause a non-carcinogenic health risk, although As may pose a cancer risk for children. This research also provides health and environmental authorities with a tool to manage such risks.

Ignimbrites within calderas host intrusions with hazardous and/or economically significant hydrothermal systems. The Hvítserkur ignimbrite at Breiðuvík caldera, north-eastern Iceland, is intruded by basaltic dykes. Our data show that the ignimbrite immediately adjacent to the dyke is hard, dark-coloured, recrystallised quartz, plagioclase, and alkali feldspar with a low permeability and porosity and frequent macrofractures. At 1-2 m from the dyke, the ignimbrite is hard, dominantly glassy with pervasive perlitic microfractures, has high permeability, but low porosity and frequent macrofractures. A narrow zone of pervasive unlithified clay exists 2 m from the dyke. Beyond this, the ignimbrite is soft and zeolite-rich, has low permeability, high porosity and fewer macrofractures. The dyke intrusion promoted a narrow zone of welding, fracturing and perlitisation in the ignimbrite resulting in high permeability and focussed alteration. Our study shows how intrusions and their thermal aureoles create vertical pathways for, and horizontal barriers to, geothermal fluid flow.

Volcanic signatures archived in polar ice sheets provide important opportunities to date and correlate ice-core records as well as to investigate the environmental impacts of eruptions. Only the geochemical characterization of volcanic ash (tephra) embedded in the ice strata can confirm the source of the eruption, however, and is a requisite if historical eruption ages are to be used as valid chronological checks on annual ice layer counting. Here we report the investigation of ash particles in a Greenland ice core that are associated with a volcanic sulfuric acid layer previously attributed to the 79 CE eruption of Vesuvius. Major and trace element composition of the particles indicates that the tephra does not derive from Vesuvius but most likely originates from an unidentified eruption in the Aleutian arc. Using ash dispersal modelling, we find that only an eruption large enough to include stratospheric injection is likely to account for the sizeable (24–85 μm) ash particles observed in the Greenland ice at this time. Despite its likely explosivity, this event does not appear to have triggered significant climate perturbations, unlike some other large extra-tropical eruptions. In light of a recent re-evaluation of the Greenland ice-core chronologies, our findings further challenge the previous dating of this volcanic event to 79 CE. We highlight the need for the revised Common Era ice-core chronology to be formally accepted by the wider ice-core and climate modelling communities in order to ensure robust age linkages to precisely dated historical and paleoclimate proxy records.

If economists have largely failed to predict or prevent the Global Financial Crisis in 2008, and the more disastrous economic collapse associated with the pandemic of 2020, what else is the profession missing? This is the question that motivates this survey. Specifically, we want to highlight four catastrophic risks – i.e., risks that can potentially result in global catastrophes of a much larger magnitude than either of the 2008 or 2020 events. The four risks we examine here are: Space weather and solar flares, super-volcanic eruptions, high-mortality pandemics, and misaligned artificial intelligence. All four have a non-trivial probability of occurring and all four can lead to a catastrophe, possibly not very different from human extinction. Inevitably, and fortunately, these catastrophic events have not yet occurred, so the literature investigating them is by necessity more speculative and less grounded in empirical observations. Nevertheless, that does not make these risks any less real. This survey is motivated by the belief that economists can and should be thinking about these risks more systematically, so that we can devise the appropriate ways to prevent them or ameliorate their potential impacts.

With the aim to investigate the rupture complexity and the radiated wave field of 2017, Mw 3.9, Ischia earthquake, south-west of Naples (Italy), we used finite-fault modeling to invert the near-source (and searched for the best-fit kinematic rupture parameters. This analysis showed that the rupture nucleated at about 600 m west of IOCA and 1.1-km depth, along a 1 km, NW-SE striking fault (i.e., thrust with right-lateral component), with a rupture velocity of about 0.7 km/s. The retrieved rupture model coupled with multipath reverberations effects related to a thin, low-velocity near-surface volcanic sedimentary layer, well explains the observed long ground motion duration and the large amplitudes recorded all over the island. Finally, the apparent source time function (STF), obtained from inverse modeling using a theoretical Green’ function (GF), is validated by implementing an empirical GF (EGF) analysis.

Ocean-island basalts (OIBs) are considered to be messengers from the deep mantle, yet the filtering effect of the plumbing systems that bring OIB melts to the surface remains poorly assessed. We investigated volcanic products from El Hierro island (Canary Islands) from textural and chemical perspectives. The majority of geochemical data cluster at relatively fractionated basaltic compositions of 5 wt% MgO. Compositions ≥10 wt% MgO are porphyritic whole rocks that accumulate mafic minerals. Near-primary melts do not erupt. Instead, we show that carrier melts (crystal-free whole rocks, glasses, and melt inclusions) are consistently buffered to low-MgO compositions during passage through the plumbing system. We tested our model of melt fractionation and crystal accumulation on a global compilation of OIBs. Similar to El Hierro, the majority of data cluster at evolved compositions of 5 wt% MgO (alkaline) to 7 wt% MgO (tholeiitic). Modeling the fractionation of OIB parental melts, we show that with 50% crystallization, OIB melts reach 5 wt% MgO with reduced density, increased volatile content, and overall low viscosity, becoming positively buoyant relative to wall rocks and highly eruptible when reaching volatile saturation at depths around the crust-mantle boundary. Under these conditions, 5 wt% MgO OIB “sweet spot” melts are propelled to the surface and erupt carrying an assortment of recycled crystals. This mechanism is consistent with the petrography and chemistry of erupted products and suggests OIB volcanoes are dominated by low-MgO basaltic melts.

The Tarim basin not only is one of the main targets for hydrocarbon exploration in China, but also hosts the Early Permian LIP, thereby providing an ideal laboratory to investigate how the LIP eruptions interact with the petroleum system in the volcanic-affected basins. Six major second-order domes were identified in the first-order dome that involves the entire Tarim LIP, based on seismic probing and lithofacies and stratigraphic observations in boreholes and the stratigraphic sections. These second-order domes are characterized by abundant Permian basaltic dykes and volcanic craters, indicative of the origin from the LIP eruption. They also are the sites of the almost all Paleozoic oil and gas reservoirs in the Tarim basin. Dating on authigenic illites collected from 20 Silurian bituminous and oil-saturated sandstone samples in the Tarim basin, along with literature data, indicates that hydrocarbon charge and emplacement in the Paleozoic reservoirs prevalently occurred during 300–255 Ma, approximately concurrent with the eruption of the Tarim LIP lavas (300–262 Ma). Therefore, we propose that the LIP eruption not only created the second-order domes that provided space for the oil and gas charge but also triggered the rapid release of hydrocarbon through the volcanic vents, thereby controlling the formation of Paleozoic oil and gas fields in the Tarim basin.

Active/recent volcanism indicates the presence of high-enthalpy resources at depth, but sometimes there is not any evidence of endogenous fluids manifestations at surface, that confirms the presence of an active geothermal system. In this study we present an extensive study of published and new diffuse 4He and 3He emission and thermal energy released data from fifteen volcanic systems, confirming a direct relationship between diffuse helium emissions and thermal energy released associated with the rise of mantle fluids. The results are useful to infer the existence of deep and/or hidden geothermal resources and to estimate roughly its potential at those areas without obvious geothermal manifestations at the surface, but with measureable anomalous emissions of 4He and 3He. Tracing diffuse He emission anomalies at the surface environment of volcanic systems provides very important information for the exploration and discovery of geothermal resources at those areas where the resources are either hidden or lie at great depth.

The sudden eruption of submerged calderas can potentially pose imminent danger to nearby communities. Hence, it is crucial to closely monitor the changes in volatile effluents in these environments. Unlike subaerial volcanoes, underwater volcanic activity is difficult to observe. Wakamiko, a submerged caldera in southern Japan shares a magma source with the active subaerial volcano, Mt. Sakurajima . Following years of inactivity, the volcanic eruptions in Mt. Sakurajima became more frequent in 2009; however, it is undetermined how the neighboring Wakamiko caldera has behaved in relation to this upsurge in activity. In this study, we assess the state of hydrothermal venting inside Wakamiko following recent disturbances in Mt. Sakurajima. Based on gas bubbles, seawater and sediment pore water measurements of samples obtained in 2015, it appears that acidic fluids enriched in 3He continue to be discharged to the seafloor. Excess 3He in the water column shows no apparent change since 2010; however, the helium isotopic ratio of the magmatic source continues to be elevated at ∼7.2 Ra. This ratio for the magmatic component is higher than previously observed in 1986 (∼6 Ra). The difference could be related to changes in the degassing activity as well as the mantle composition of the magmatic source. Using the new data from sediment pore water, we estimate the diffusive fluxes of 3He and 4He through the seafloor at 16.05 atoms cm-2s-1 and 1.52 x 106 atoms cm-2s-1, respectively. We also calculated the vent 3He flux at 3.38 x104 atoms cm-2s-1. With the use of the 3He flux, we calculated the diffusive CO2 flux from Wakamiko at 1.41 x 106 mol yr-1 and the vent flux at 3.72 x 108 mol yr-1. The available data that we have are still limited and a more frequent and longer observation is necessary to deduce the temporal changes in Wakamiko and its relation to the volcanic activity of Mt. Sakurajima.

Lava tubes are buried channels that transport thermally insulated lava. Nowadays, lava tubes on the Moon are believed to be empty and thus indicated as potential habitats for humankind. In recent years, several studies investigated possible lava tube locations, considering the gravity anomaly distribution and surficial volcanic features. This article proposes a novel and unsupervised method to map candidate buried empty lava tubes in radar sounder data (radargrams) and extract their physical properties. The approach relies on a model that describes the geometrical and electromagnetic (EM) properties of lava tubes in radargrams. According to this model, reflections in radargrams are automatically detected and analyzed with a fuzzy system to identify those associated with lava tube boundaries and reject the others. The fuzzy rules consider the EM and geometrical properties of lava tubes, and thus, their appearance in radargrams. The proposed method can address the complex task of identifying candidate lava tubes on a large number of radargrams in an automatic, fast, and objective way. The final decision on candidate lava tubes should be taken in postprocessing by expert planetologists. The proposed method is tested on both a real and a simulated data set of radargrams acquired on the Moon by the Lunar Radar Sounder (LRS). Identified candidate lava tubes are processed to extract geometrical parameters, such as the depth and the thickness of the crust (roof).

The activity of the 2018–2019 eruption of Kuchinoerabujima Volcano in Japan changed from continuous ejection of ash-laden plumes between October 21 and the middle of December, to intermittent explosive activity accompanied by several pyroclastic density currents until January 2019. To understand the behaviors of magma and hydrothermal fluid that controlled the eruptive sequence, we carried out component analysis, X-ray diffractometry, and leachate analysis for ash samples. The proportion of non-altered volcanic ash particles is ~ 15% in the earlier phase, then it decreased to less than 10% in the later explosive phase. Accordingly, the mineral assemblage of the volcanic ash samples changed from plagioclase-dominant to sulfate minerals-dominant. Concentration of SO42− and Cl/SO4 values of the ash-leachates decreased toward the later activity. These results indicate that the proportion of fresh volcanic rocks decreased and sulfuric acid fluid-derived sulfate minerals increased toward the later activities. Consequently, the 2018–2019 eruption at Kuchinoerabujima Volcano changed from magmatic activity to phreatomagmatic activity. Weak glowing of the crater was observed during the magmatic activity, indicating the volcanic conduit was hot enough to dry up the sub-volcanic hydrothermal system. The following phreatomagmatic activity indicates that the hydrothermal fluid recharged after the magmatic eruption phase. Recharge of the hydrothermal fluid likely caused the variation of the eruption style, and is a process that may control the evolution of hazards during future eruption scenarios at similar active volcanoes in Japan and worldwide. Graphical Abstract

Detection of volcanic hazards are important for public health and aircraft safety. In this study, we investigate the ability to detect volcanic plume using a simple analytic approach based on Global Navigate Satellite System (GNSS) observations, numerical weather model (NWM) fields and ground-based automatic weather stations. The GNSS data obtained from the network located around the Sakurajima volcano in Japan was used to estimate zenith tropospheric delays (ZTD) in October 2014, when the volcano showed an increase in activity. For our analysis, the ZTDs reconstructed in the ray tracing approach were applied to ERA5 reanalysis, and then compared with the ZTDs estimated by the Natural Resources Canada web GNSS processing software. Four analytical techniques were employed: target, space, time, and eventually, time and space differentiation. Meteorological data from nearby weather stations, as well as ERA5 reanalysis, helped separate the ZTD increments connected to weather conditions and volcanic activity. The results revealed that our approach correctly demonstrates Sakurajima activity in four cases out of five. We also noted a correlation between the results of our calculations and plume spreading direction data in 25% of cases.

There has been a recent rise in the uses and applications of passive seismic data, such as tomographic imaging, volcanic monitoring, and hydrocarbon exploration. Consequently, the sharp increase in passive seismic applications requires real-time event detection capabilities with high accuracy. Proper analysis of such events depends largely on the signal-to-noise ratio improvement through noise suppression techniques. Recent advances in the fields of signal processing and deep learning coupled with the available computational resources provide a great opportunity to address this challenge. In this work, a workflow is proposed where a residual deep neural network is customized and employed to detect passive seismic events. The automated detection is followed by a denoising step to extract the signal of interest from background noise using an IIR Wiener filter. The proposed method does not require any prior knowledge of the signal/noise, and therefore, it can work with various types of signals/noises. Another benefit of the proposed detection method is that the deep neural network is trained only on synthetic seismic data without the need to use real data in the training process. Nevertheless, it exhibits high accuracy in detecting and denoising events from real passive seismic data sets. In particular, field seismic data is recorded in northern Saudi Arabia and used to test the complete detection and denoising method. The detection method proved its capability of detecting events automatically in large data sets and in real time (due to off-line training).

In November 2019, the fourth Volcano Observatory Best Practices workshop was held in Mexico City as a series of talks, discussions, and panels. Volcanologists from around the world offered suggestions for ways to optimize volcano-observatory crisis operations. By crisis, we mean unrest that may or may not lead to eruption, the eruption itself, or its aftermath, all of which require analysis and communications by the observatory. During a crisis, the priority of the observatory should be to acquire, process, analyze, and interpret data in a timely manner. A primary goal is to communicate effectively with the authorities in charge of civil protection. Crisis operations should rely upon exhaustive planning in the years prior to any actual unrest or eruptions. Ideally, nearly everything that observatories do during a crisis should be envisioned, prepared, and practiced prior to the actual event. Pre-existing agreements and exercises with academic and government collaborators will minimize confusion about roles and responsibilities. In the situation where planning is unfinished, observatories should prioritize close ties and communications with the land and civil-defense authorities near the most threatening volcanoes.To a large extent, volcanic crises become social crises, and any volcano observatory should have a communication strategy, a lead communicator, regular status updates, and a network of colleagues outside the observatory who can provide similar messaging to a public that desires consistent and authoritative information. Checklists permit tired observatory staff to fulfill their duties without forgetting key communications, data streams, or protocols that need regular fulfilment (Bretton et al. Volcanic Unrest. Advances in Volcanology, 2018; Newhall et al. Bull Volcanol 64:3–20, 2020). Observatory leaders need to manage staff workload to prevent exhaustion and ensure that expertise is available as needed. Event trees and regular group discussions encourage multi-disciplinary thinking, consideration of disparate viewpoints, and documentation of all group decisions and consensus. Though regulations, roles and responsibilities differ around the world, scientists can justify their actions in the wake of an eruption if they document their work, are thoughtful and conscientious in their deliberations, and carry out protocols and procedures developed prior to volcanic unrest. This paper also contains six case studies of volcanic eruptions or observatory actions that illustrate some of the topics discussed herein. Specifically, we discuss Ambae (Vanuatu) in 2017–2018, Kīlauea (USA) in 2018, Etna (Italy) in 2018, Bárðarbunga (Iceland) in 2014, Cotopaxi (Ecuador) in 2015, and global data sharing to prepare for eruptions at Nyiragongo (Democratic Republic of Congo). A Spanish-language version of this manuscript is provided as Additional file 1.

The catastrophic phenomena of the Earth should include volcanic eruptions, which sometimes lead to the death of people, but mostly to significant economic losses. As a vivid example of the great catastrophism of these phenomena, we can cite the events associated with the eruption of the Krakatoa volcano, which began in May 1883 and ended with a series of powerful explosions on August 26 and 27, 1883, as a result of which most of the island of Krakatoa was destroyed. More recently, approximately the same event occurred, but its power was much less than the power of the eruption and explosion of the Krakatoa volcano. On December 20, 2021, a volcanic eruption began on the island of Hunga-Tonga-Hunga-Haapai in the Tonga archipelago, and on January 15, 2021, at 04:15 UTC, the eruption turned into an active explosive phase, at the final stage of which the volcano exploded. After the explosion, a shock wave formed, which circled the Earth several times, exciting on its way regional fluctuations of individual layers of the atmosphere, seas and their parts, elastic vibrations of the Earth's crust in the infrasound frequency range. In addition, according to some data, atmospheric Lamb waves were excited, and tsunami waves were generated in certain areas of the Pacific Ocean. The article focuses on the excitation of infrasound vibrations in the atmosphere–hydrosphere–lithosphere system caused by a passing atmospheric pulse generated during the explosion of the Hunga-Tonga-Hunga-Haapai volcano., К катастрофическим явлениям Земли надо отнести извержения вулканов, которые иногда приводят к гибели людей, но в основном к значительным экономическим потерям. В качестве яркого примера большой катастрофичности данных явлений можно привести события, связанные с извержением вулкана Кракатау, начавшееся в мае 1883 года и завершившееся серией мощных взрывов 26 и 27 августа 1883 года, в результате которых большая часть острова Кракатау была уничтожена. Это извержение вулкана считается одним из самых смертоносных и разрушительных в истории: около 36417 человек погибли в результате самого извержения и вызванного им цунами, были полностью уничтожены 165 городов и поселений. Совсем недавно произошло примерно такое же событие, но мощность его была гораздо меньше мощности извержения и взрыва вулкана Кракатау. 20 декабря 2021 года на острове Хунга-Тонга-Хунга-Хаапай на архипелаге Тонга началось извержение вулкана, а 15 января 2021 года в 04:15 UTC извержение перешло в активную взрывную фазу, на заключительном этапе которой вулкан взорвался. Центральная часть кальдеры вулкана площадью примерно 5 км2 находилась на глубинах от 150 до 200 м. По оценке специалистов NASA мощность взрыва составила 10 мегатонн в тротиловом эквиваленте. После взрыва образовалась ударная волна, которая несколько раз обогнула Землю, возбуждая на своём пути региональные колебания отдельных слоёв атмосферы, сейши морей и их частей, упругие колебания земной коры в инфразвуковом диапазоне частот. Кроме того, по отдельным данным были возбуждены атмосферные волны Лэмба, а на отдельных акваториях Тихого океана – волны цунами. В статье основное внимание уделено возбуждению инфразвуковых колебаний в системе «атмосфера – гидросфера – литосфера», вызванных проходящим атмосферным импульсом, сгенерированным при взрыве вулкана Хунга-Тонга-Хунга-Хаапай.

Determining outline, volume and effusion rate during an effusive volcanic eruption is crucial as it is a major controlling factor of the lava flow lengths, the prospective duration and hence the associated hazards. We present for the first time a multi-sensor thermal-and-topographic satellite data analysis for estimating lava effusion rates and volume. At the 2021 lava field of Cumbre Vieja, La Palma, we combine VIIRS + MODIS thermal data-based effusion rate estimates with DSMs analysis derived from optical tri-stereo Pléiades and TanDEM-X bi-static SAR-data. This multi-sensor-approach allows to overcome limitations of single-methodology-studies and to achieve both, high-frequent observation of the relative short-term effusion rate trends and precise total volume estimates. We find a final subaerial-lava volume of $$212\times {10}^{6}\pm 13\times {10}^{6}\; \text{m}^{3}$$ 212 × 10 6 ± 13 × 10 6 m 3 with a MOR of 28.8 ± 1.4 m3/s. We identify an initially sharp eruption-rate-peak, followed by a gradually decreasing trend, interrupted by two short-lived-peaks in mid/end November. High eruption rate accompanied by weak seismicity was observed during the early stages of the eruption, while during later stage the lava effusion trend coincides with seismicity. This article demonstrates the geophysical monitoring of eruption rate fluctuations, that allows to speculate about changes of an underlying pathway during the 2021 Cumbre Vieja eruption.

The Joint Polar Satellite System (JPSS) mission has provided over ten years of high-quality data products for environment forecasting and monitoring through the current Suomi National Polar-orbiting Partnership (S-NPP) and NOAA-20 satellites. Particularly, the sensor data record (SDR) and the derived environmental data record (EDR) products from the Visible Infrared Imaging Radiometer Suite (VIIRS), the Cross-track Infrared Sounder (CrIS), the Advanced Technology Microwave Sounder (ATMS), and the Ozone Mapping and Profiler Suite (OMPS) offer an unprecedented opportunity to observe severe weather and environmental events over the Earth. This paper presents the observations about atmospheric features of the Hunga Tonga Volcanic eruption of January 2022, e.g., the gravity wave, volcanic cloud, and aerosol (sulfate) plume phenomena, by using the ATMS, CrIS, OMPS, and VIIRS SDR and EDR products. Powerful gravity waves ringing through the atmosphere after the eruption of the Hunga Tonga volcano are discovered at two CrIS upper sounding channels (670 cm−1 and 2320 cm−1) in the deviations of the observed brightness temperature (O) from the simulated baseline brightness temperature (B) using the Community Radiative Transfer Model (CRTM), i.e., O—B. A similar pattern is also observed in the ATMS global maps at channel 15, whose peak weighting function is around 40 km, showing the atmospheric disturbance caused by the eruption that reached 40 km above the surface. The Tonga volcanic cloud (plume) was also captured by the OMPS SO2 EDR product. The gravity wave features were also captured in the native resolution image of the S-NPP VIIRS I-5 band nighttime observations. In addition, the VIIRS Aerosol Optical Depth (AOD) captured and tracked the volcanic aerosol (sulfate) plume successfully. These discoveries demonstrate the scientific potential of the JPSS SDR and EDR products in monitoring and tracking the eruption of the Hunga Tonga volcano and its severe environmental impacts. This paper presents the atmospheric features of the Hunga Tonga volcano eruption that is uniquely captured by all four advanced sensors onboard JPSS satellites, with different spectral coverages and spatial resolutions.

The hydraulic parameters of porous media, such as porosity (φ) and hydraulic conductivity (K), are the most important factors for planning and managing water exploitation from aquifers. This study aims to estimate the hydraulic conductivity parameters using the geoelectric method on volcanic deposits on the northern slope of Mount Ciremai. For this purpose, four data types were used to estimate K and φ, including lithological profiles, water table, groundwater quality, pumping test data, and vertical electrical sounding (VES). Based on Archie's law and Kozeny's equation, we get the alpha (α) values and cementation factor (m) from which the median values of α = 1.01 and m = 1.36 represent the studied aquifer. The porosity (φ) of the aquifer varies from 0.097 to 0.187 with an average of 0.141 and is spatially related to the hydraulic conductivity (kgm), which varies from 4.97 × 10-6 to 6.75 × 10-5 m/s after the application of Kozeny's equation. The hydraulic conductivity (Kp) calculated from the pumping tests varies from 9.07 × 10-6 to 1.06 × 10-4 m/s and is strongly correlated (r = 0.87). Furthermore, a relation between resistivity and hydraulic conductivity was established for the studied aquifer to estimate these parameters in sites lacking data.

The 2022 eruption of the Hunga Tonga-Hunga Ha'apai volcano excited an atmospheric Lamb wave, which induced a fast-traveling tsunami. This tsunami was driven by the pressure-forced wave traveling at the speed of the Lamb wave and, thus, was much faster than conventional tsunamis. This was the first case in which ocean bottom monitoring systems widely observed an air pressure-induced tsunami. We found that the pressure-forced waves split and generated ocean gravity waves after passing the Japan Trench based on the S-net data. Our simulations show that changes in water depth can amplify or decrease the pressure-forced wave. Simultaneously, an ocean gravity wave is generated due to the conservation of water volume. Because the ocean gravity wave was slower than the pressure-forced wave near Japan, it was separated from, and traveled behind, the pressure-forced wave. We explained the wave separation phenomenon and reproduced the waveforms of different splitting stages observed by the stations near the Japan Trench. Graphical Abstract

Morphometric parameters have been used to describe and classify the shape of volcanic edifices, but the processes that control these parameters are not fully understood. Here we investigate the influence of the changes in eruptive volume and magma viscosity on the edifice morphology of a simple polygenetic volcano with a fixed stable vent using analogue experiments in the laboratory. We ran the experiments by ejecting vegetable oil repeatedly at a static location in a temperature-controlled room with an adequate interval between ejections to allow this material to solidify. The experiments comprised four different scenarios: constant ejection volume and viscosity, linearly decreasing ejection volume with constant viscosity, exponentially decreasing ejection volume with constant viscosity, and increasing viscosity with constant ejection volume. We built digital elevation models from images captured by digital cameras after each ejection using photogrammetry method. We describe the shapes of the edifices using morphometric parameters, such as height, basal width, H/W ratio, volume, slope, circularity, and regularity. The experiments with decreasing ejection volume produced taller edifices with steeper slopes, especially near the summit, compared to the edifice produced with constant ejection volume. A similar finding was also observed for the edifice resulting from the experiment with increasing viscosity. The circularity and regularity indexes were insignificantly influenced by ejection volume and viscosity changes. Instead, these parameters vary with the height fraction of the edifice where the lower part is more circular, but irregular compared to the upper part. Based on the changes of morphometric variables throughout the experiments, we propose three development stages of volcanic edifice growth: basal foundation, flank construction, and vertical build-up. The development stage in which the edifice currently grows can be inferred from the relative changes in the eruptive volume and the magma viscosity. Therefore, the quantitative characterization of a natural volcanic edifice's morphology can be interpreted to explain the processes that influenced it and its stage of growth. National Research Foundation (NRF) This work is supported by the National Research Foundation of Singapore, Grant NRF-NRFF2016-04 to CBdM.

International audience; The thermal properties of volcanic materials are required for modelling and for understanding volcanic surface heat fluxes and timescales for cooling magma. However, compared to volcanic rocks, there are relatively few thermal property data for unlithified granular volcanic materials. Here, we measured the thermal properties of a suite of hydrothermally altered powders from La Soufrière de Guadeloupe (Eastern Caribbean) as a function of water saturation degree. Our data show, under dry conditions, that thermal conductivity and thermal diffusivity decrease, and that specific heat capacity does not change systematically, as a function of the degree of alteration of the unlithified granular material. For example, thermal conductivity decreases from ~0.3 to ~0.2 W·m−1·K−1 as the quantity of alteration minerals in the samples increases from ~10 to ~70 wt%. We interpret the decrease in thermal conductivity with increasing alteration as the result of the lower thermal conductivity of the alteration mineral assemblage relative to the unaltered assemblage. Our data also show that thermal conductivity increases from ~0.2–0.3 to ~0.8–1.1 W·m−1·K−1 as saturation degree increases from dry to at, or close to, complete saturation, due to the higher thermal conductivity of water compared to air. We show that an empirical model for variably saturated granular media is in general agreement with our data and provides a framework to predict the thermal conductivity of unlithified granular volcanic materials as a function of saturation degree. The data and modelling provided herein can help improve heat flux calculations designed to inform on volcanic and geothermal processes.

The Mascarene Islands in the western Indian Ocean, encompassing La Réunion, Mauritius, and Rodrigues, are the recent (, Geochimica et Cosmochimica Acta, 355, ISSN:0016-7037, ISSN:1872-9533

К катастрофическим явлениям Земли надо отнести извержения вулканов, которые иногда приводят к гибели людей, но в основном к значительным экономическим потерям. В качестве яркого примера большой катастрофичности данных явлений можно привести события, связанные с извержением вулкана Кракатау, начавшееся в мае 1883 года и завершившееся серией мощных взрывов 26 и 27 августа 1883 года, в результате которых большая часть острова Кракатау была уничтожена. Это извержение вулкана считается одним из самых смертоносных и разрушительных в истории: около 36 417 человек погибли в результате самого извержения и вызванного им цунами, были полностью уничтожены 165 городов и поселений. Совсем недавно произошло примерно такое же событие, но мощность его была гораздо меньше мощности извержения и взрыва вулкана Кракатау. 20 декабря 2021 года на острове Хунга-Тонга-Хунга-Хаапай на архипелаге Тонга началось извержение вулкана, а 15 января 2021 года в 04:15 UTC извержение перешло в активную взрывную фазу, на заключительном этапе которой вулкан взорвался. Центральная часть кальдеры вулкана площадью примерно 5 км2 находилась на глубинах от 150 до 200 м. По оценке специалистов NASA мощность взрыва составила 10 мегатонн в тротиловом эквиваленте. После взрыва образовалась ударная волна, которая несколько раз обогнула Землю, возбуждая на своём пути региональные колебания отдельных слоёв атмосферы, сейши морей и их частей, упругие колебания земной коры в инфразвуковом диапазоне частот. Кроме того, по отдельным данным были возбуждены атмосферные волны Лэмба, а на отдельных акваториях Тихого океана – волны цунами. В статье основное внимание уделено возбуждению инфразвуковых колебаний в системе «атмосфера – гидросфера – литосфера», вызванных проходящим атмосферным импульсом, сгенерированным при взрыве вулкана Хунга-Тонга-Хунга-Хаапай., The catastrophic phenomena of the Earth should include volcanic eruptions, which sometimes lead to the death of people, but mostly to significant economic losses. As a vivid example of the great catastrophism of these phenomena, we can cite the events associated with the eruption of the Krakatoa volcano, which began in May 1883 and ended with a series of powerful explosions on August 26 and 27, 1883, as a result of which most of the island of Krakatoa was destroyed. More recently, approximately the same event occurred, but its power was much less than the power of the eruption and explosion of the Krakatoa volcano. On December 20, 2021, a volcanic eruption began on the island of Hunga-Tonga-Hunga-Haapai in the Tonga archipelago, and on January 15, 2021, at 04:15 UTC, the eruption turned into an active explosive phase, at the final stage of which the volcano exploded. After the explosion, a shock wave formed, which circled the Earth several times, exciting on its way regional fluctuations of individual layers of the atmosphere, seas and their parts, elastic vibrations of the Earth's crust in the infrasound frequency range. In addition, according to some data, atmospheric Lamb waves were excited, and tsunami waves were generated in certain areas of the Pacific Ocean. The article focuses on the excitation of infrasound vibrations in the atmosphere–hydrosphere–lithosphere system caused by a passing atmospheric pulse generated during the explosion of the Hunga-Tonga-Hunga-Haapai volcano., Гидросфера. Опасные процессы и явления, Выпуск 2 2023, Pages 126-138

On 27 November 2022, an eruption started at the Mauna Loa (Hawaii; USA) volcano after about 38 years of quiescence. The eruption took place at the summit caldera; the day after, it migrated to the upper Northeast Rift Zone, where lava effusion initially occurred from three fissure vents.In this work, we investigate the Mauna Loa 2022 eruption, ending on 13 December, by means of a virtual network of multi-sensor infrared satellite observations. In particular, we show the results achieved by implementing the Normalized Hotspot Indices (NHI) on GOES-R ABI data, at 10 min temporal resolution, and by using Sentinel-2 MSI and Landsat-8/9 OLI/OLI-2 observations at mid-high spatial resolution via the Google Earth Engine tool developed to map volcanic thermal anomalies at global scale. Both the eruption onset and the short-term variations of thermal activity were well identified by NHI, using GOES-R ABI data. Moreover, an accurate mapping and characterization of active lava flows was performed. These results confirm that SWIR (short wave infrared) observations, at different temporal and spatial resolution, if properly analysed, may support the monitoring and surveillance of active volcanoes from space., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

Large volcanic eruptions impact climate through the injection of ash and sulfur gas into the atmosphere. While the ash particles fall out rapidly, the gas is converted to sulfate aerosols, which reflect solar radiation in the stratosphere and cause a cooling of the global mean surface temperature. Earlier studies suggested that major volcanic eruptions resulted in positive mass balances and advances of glaciers. Here we perform a multivariate analysis to decompose global glacier mass changes from 1961 to 2005 into components associated with anthropogenic influences, volcanic and solar activity, and El Niño Southern Oscillation (ENSO). We find that the global glacier mass loss was mainly driven by the anthropogenic forcing, interrupted by a few years of intermittent mass gains following large volcanic eruptions. The relative impact of volcanic eruptions is dwindling due to strongly increasing greenhouse gas concentrations since the mid of the 20th century. Furthermore, our study indicates that solar activity and ENSO have limited impacts on climate conditions at glacier locations and that volcanic eruptions alone can hardly explain decadal periods of glacier advances documented since the 16th century., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)