The deep-sea areas of the Cabo Verde Archipelago remain largely unexplored, with seamounts standing out as the most prominent and abundant geomorphological features. The ecological significance of these underwater structures is well-documented in various regions of the planet, as they often serve as biodiversity hotspots, stepping stones for species connectivity and, in some cases, areas with high levels of endemism. However, the biology and ecology of the seamounts around Cabo Verde are still largely unknown. Preliminary studies of the geomorphology, oceanographic characteristics and ecology of specific features suggest that the Cabo Verde seamount network — comprising 14 known conspicuous seamounts as well as smaller elevations less than 1000 m — harbours high biological diversity. That biodiversity associated with the Cabo Verde seamounts spans a wide range of forms, from microscopic organisms to cetaceans, encompassing both pelagic and benthic communities. Commercial activities associated with seamounts, in particular fishing, are a critical aspect to consider for ecosystem management. Evaluating their current uses, future prospects, and the existing and potential threats the Cabo Verde seamounts face is essential for effective and sustainable marine spatial planning. This study reviews and synthesises the current knowledge on the Cabo Verde seamounts within its Exclusive Economic Zone (EEZ), focusing on their environmental and biological aspects, including geology, oceanography, and associated biological communities. Key topics include primary production, zooplankton communities, benthic organisms, large vertebrates such as elasmobranchs, sea turtles, seabirds, and cetaceans, as well as microbes and trophic linkages. Additionally, this review explores the socio-economic dimensions linked to seamounts, highlighting their importance to the local economy and emphasizing the need for effective marine spatial management plans. These considerations are crucial for balancing conservation efforts with sustainable use, ensuring the long-term health of these vital underwater ecosystems.

The Timanfaya eruption on Lanzarote (1730 to 1736) was among the largest historic eruptions on any ocean island, and understanding their eruption dynamics can help to enhance hazard mitigation measures. Gabbroic xenoliths with MORB-type mineral compositions, interpreted as fragments of the Jurassic ocean crust, were transported to the surface during the eruption. The xenoliths have to variable extents been affected by heating, causing formation of intergranular reaction rims, and also partial melting reflected by melt-filled veins. Twopyroxene thermobarometry using the abundant orthopyroxene exsolution lamellae in clinopyroxene give average formation temperatures of 865 degrees C. CO2-dominated fluid inclusions in plagioclase, olivine and clinopyroxene show two density modes, the main mode at 0.62 f 0.11 g/cm3 with a skewed distribution towards higher densities up to 0.80 g/cm3, and a less prominent mode at 0.28 f 0.10 g/cm3, respectively. The primary fluid inclusions are contained in the main mode. Coexistence of secondary CO2-dominated fluid inclusions with melt inclusions demonstrate late-stage magmatic temperatures in the xenoliths. We suggest that the xenoliths originated as magma chamber wall rocks, and were entrained in the Timanfaya magmas at pressures of about 315 f 95 MPa. Heating of the xenoliths to magmatic temperatures during limited magma stagnation in the lower crust led to isobaric re-equilibration of the primary fluid inclusions. Some xenoliths record an additional transient stagnation level at 100 f 45 MPa, which corresponds to the shallowest level of syn-eruption magma stagnation. This ascent history is strikingly similar to the events recorded during the 2021 La Palma eruption, and to those of mafic magmas on ocean islands worldwide, suggesting that such lower crustal magma stagnation beneath ocean islands is the rule rather than the exception.

Situated in the Cabo Verde Archipelago, Fogo is among the most active oceanic volcanoes in the Atlantic, hosting frequent eruptions some of which were highly explosive and at least one gravitational flank collapse in the last 100 kyr. This study presents new volcanic glass shard geochemical data with high spatial distribution from 54 sites comprising samples from both pre- and post-collapse times. The analyzed glasses comprise basanites, tephrites, and foidites with a subset extending into the phonolite field. The glass compositions complement bulk rock data particularly in the range between 6 and 1 wt.

Cabo Verde hosts unique, highly biodiverse marine ecosystems that thrive on volcanic seamounts and island slopes. These ecosystems are shaped by distinct oceanographic dynamics, influenced by the southeastern edge of the North Atlantic Subtropical Gyre (NASTG) and by seasonal upwelling. To explore regional oceanographic variability over time, this study investigates Holocene (last 11.7 ka) sediments using multi-proxy palaeoenvironmental reconstructions from a short core retrieved from ∼ 4,400 m water depth off Cabo Verde.During the Early Holocene, year-round upwelling, or an intensified Guinea Dome, may have inhibited the development of the strong summer stratification characteristic of the modern regional non-upwelling season. Despite humid conditions over the continent, sea surface temperatures (SSTs) remained relatively low during this subepoch, diverging from the present-day pattern in Northwest Africa, where the wet season is marked by weaker upwelling and higher SSTs. This oceanographic state was likely driven by precession-induced insolation changes associated with the precession minimum, which may have modified seasonal regional wind regimes and influenced broader atmospheric processes. Teleconnections related to transitional postglacial conditions and/or continental climate feedbacks, may also have played a role. The Middle Holocene, corresponding to the most humid conditions of this epoch in Northwest Africa, is characterized by reduced upwelling and an eastward expansion of the NASTG, inferred from warmer subsurface conditions at our study site. This interval also provides tentative evidence for enhanced input of North Atlantic Deep Water (NADW) into the Northeast Atlantic Bottom Water (NEABW). During the Late Holocene, intensified upwelling and a reduced influence of the NASTG, possibly due to a westward retraction of its eastern boundary, are suggested at our site, occurring under arid conditions in Northwest Africa.These results highlight that, despite the overall climatic stability of the Holocene, oceanographic conditions off Cabo Verde experienced significant changes in seasonal upper ocean stratification, upwelling, subtropical gyre influence, and deep-water structure. Such insights improve our understanding of regional climate-ocean interactions, helping to refine climate models and improve predictions of ecosystem responses in this sensitive marine region.

During research expedition SO299 with the German RV Sonne, we discovered the first deep-sea hydrothermal vent system along the Tabar-Lihir-Tanga-Feni island chain in northeastern Papua New Guinea. The Karambusel vent field is hosted by a volcanic center on the western flank of Conical Seamount that formed ~ 89 ka ago. Karambusel is remarkable in that it hosts both a fossil high-temperature, gold-rich mineralization and an active low-temperature (< 51 °C) vent system precipitating arsenic-, antimony-, thallium-, and mercury-rich sulfide minerals. Chemosymbiotic fauna is associated with the vent system and we identified more endemic species than in previous studies on nearby seeps. Our study shows that the magmatic event at Karambusel likely triggered the epithermal mineralization at Karambusel and at the central summit of Conical Seamount. The current hydrothermal fluids originate from condensed magmatic vapor or connate fluids. Gas bubbles were observed at some vent sites and the proportion of methane in the gas phase exceeds that of any other hydrothermal vent system. The composition of the light hydrocarbons points towards a thermogenic origin. Karambusel is thus the first hybrid magmatic-hydrothermal vent and hydrocarbon seep system discovered globally which explains the highly endemic vent fauna as a consequence of the unique ecological niche.

The amounts of volatiles emitted from large Plinian eruptions are typically estimated using the difference between their concentration in silicate melt inclusions formed at depth, and their concentration in the partially degassed glassy groundmass of tephras (the so-called petrologic method). However, a pre-eruptive fluid phase coexisting with the magma prior to eruption may add significantly to the emission budgets. We have combined previously published chlorine emission data obtained by the petrologic method from seven Plinian eruptions along the Central American Volcanic Arc (CAVA) with new data obtained from magmatic fluid inclusions in the same samples. The presence of the magmatic fluid inclusions demonstrates the pre-eruptive criticality of these volcanic systems. The pre-eruptive magmatic fluid phase of silicic CAVA eruptions is water dominated, and contains on average 5 ± 3.5 mass

The closely spaced late glacial Daun and Gillenfeld maar clusters at the maar type locality in western Eifel (Germany) are commonly interpreted to be of phreatomagmatic origin powered by thermohydraulic explosions occurring initially at a depth of 200–300 m below the surface. Our reconnaissance work focusing on the iconoclastic water-filled Pulvermaar (PM) deposits (a funnel-shaped crater 74 m deep and 700 m in diameter surrounded by a tephra ring) and other nearby maars has provided intriguing evidence that CO2-dominated pyroclastic processes at a depth of several kilometers may have been a fundamental factor in generating the volumetrically abundant volcanic pellets (aka subspherical lava lapilli) and the rounded, lava-coated fragments of plutonic and metamorphic rocks (named nodules here) in these deposits. Phreatomagmatic explosions probably contributed to near-surface country rock fragmentation and crater foundering. Supporting lines of evidence for the role of CO2 include the following: (1) the likely high CO2-concentration of the melilite-nephelinite magma; (2) fragments of carbonatite (alkali feldspar intergrown with carbonate) in several maar deposits including the nearby ca. 11 000-year-old Ulmen maar deposits, the youngest volcano in Germany; (3) strongly rounded plutonic and gneiss nodules up to ca. 35 cm in diameter, both interpreted to be of mid-crustal derivation at ca. 20 km depth. The nodules record a complex multiphase dynamic history at depth that commences with an earlier phase of intruded melilite nephelinite into a metamorphic gneissic carapace that was largely crystallized at the time of the eruption. Subsequently, these plutonic as well as the metamorphic rocks were fragmented, followed by thorough milling and rounding of the fragments and eventual lava spray-coating of both types of nodules by a later phase of intruded gas-rich nephelinite magma that was compositionally identical to the older resident intrusion. The prominent role of these processes is reflected by the abundance of volcanic pellets in the lower exposed PM tephra ring deposits and by their dominance in the upper finer-grained well-bedded maar deposits. The pellets are composed of agglutinated smaller nephelinite lapilli and crystal fragments that were possibly derived from collided and fragmented plutonic nodules. The collection of nodules and pellets was most likely transported upward, largely by CO2-flushing and by continuous milling in the transport system, and joined by Devonian rock fragments closer to the surface. In the final stages of ascent, this was probably accompanied by near-surface phreatomagmatic processes including crater-formation.

Fracture zones were recognized to be an integral part of the seabed long before plate tectonics was established. Later, plate tectonics linked fracture zones to oceanic transform faults, suggesting that they are the inactive and hence fossil trace of transforms. Yet, scientist have spent little time surveying them in much detail over the last three decades. Recent evidence (Grevemeyer, I., Rüpke, L.H., Morgan, J.P., Iyer, K, and Devey, C.W., 2021, Extensional tectonics and two-stage crustal accretion at oceanic transform faults, Nature, 591, 402–407, doi:10.1038/s41586-021-03278-9) suggests that the traditional concept of transform faults as being conservative (non-accretionary) plate boundary faults might be wrong. Instead, transform faults are always deeper than the associated fracture zones and numerical modelling results suggest that transform faults seem to suffer from extensional tectonics below their strike-slip surface fault zone. In 2021, we tested this hypothesis by collecting, in a pilot study, micro-seismicity data from the Oceanographer transform fault which offsets the Mid-Atlantic Ridge by 120-km south of the Azores near 35°N. Analysis of 10-days of seismicity data recorded at 26 ocean-bottom-seismometers and hydrophones showed 10-15 local earthquakes per day. Furthermore, a sparse network recorded micro-earthquakes for three months. Joint interpretation of the data shows that earthquakes away from the ridge-transform intersections cluster along the fault trace imaged in bathymetric data and focal mechanisms support strike-slip motion. However, at the ridge-transform intersections seismicity does not mimic a right-angular plate boundary; instead, seismicity occurs below the inside corner and focal mechanism indicate extensional tectonics. In addition, we put published micro-earthquake data from surveys conducted in the 1970 to 1980s from the Oceanographer, Kane and Vema transform fault in a new context by plotting them onto modern swath-bathymetric data. In concert, micro-seismicity supports features found in numerical simulations, revealing that transform faults have an extensional as well as a strike-slip component.

The Tabar-Lihir-Tanga-Feni (TLTF) island chain in northeastern Papua New Guinea formed by tectonic and alkaline to shoshonitic magmatic activity since the Pliocene. Several volcanic centers are CuAu mineralized including the world-class Ladolam Au deposit and Conical Seamount south of Lihir. The latter has been recognized as a juvenile analogue to the Ladolam deposit located on-shore. Whereas the mineralization at Conical Seamount is reasonably well studied, the specific magmatic processes that promote epithermal mineralization at this seamount but not at others are poorly understood. Here, we present new petrological and geochemical data from Conical Seamount, and compare them with those from the barren (unmineralized) Edison, Tubaf and New World seamounts nearby. We focus on whole rock compositions and major and trace element analysis of melt inclusions and minerals including clinopyroxene, sulfide and magnetite. We combine our observations with modelled constraints on mantle source composition and partial melting as well as magma evolution. A first-stage melting leaves a residual mantle source enriched in Au. Second-stage melting of a previously subduction-metasomatized mantle generally promotes the transfer and concentration of metals and volatiles in the ascending melts. These magmas are unlikely to control ore formation as all seamounts show evidence for similar mantle sources and parental melt composition. However, the presence of a shallow crustal magma chamber is unique to Conical Seamount. It is characterized by frequent melt replenishments and extensive magma fractionation leading to sulfide and magmatic volatile saturation. These specific magma chamber processes lead to the pre-enrichment of the magma in chalcophile elements including Au, while sulfide saturation coeval with magmatic volatile exsolution provide the way for an effective Au transfer from the magmatic to the epithermal system.

AimSeamounts are conspicuous geological features with an important ecological role and can be considered vulnerable marine ecosystems (VMEs). Since many deep-sea regions remain largely unexplored, investigating the occurrence of VME taxa on seamounts is challenging. Our study aimed to predict the distribution of four cold-water coral (CWC) taxa, indicators for VMEs, in a region where occurrence data are scarce.LocationSeamounts around the Cabo Verde archipelago (NW Africa).MethodsWe used species presence-absence data obtained from remotely operated vehicle (ROV) footage collected during two research expeditions. Terrain variables calculated using a multiscale approach from a 100-m-resolution bathymetry grid, as well as physical oceanographical data from the VIKING20X model, at a native resolution of 1/20 degrees, were used as environmental predictors. Two modelling techniques (generalized additive model and random forest) were employed and single-model predictions were combined into a final weighted-average ensemble model. Model performance was validated using different metrics through cross-validation.ResultsTerrain orientation, at broad scale, presented one of the highest relative variable contributions to the distribution models of all CWC taxa, suggesting that hydrodynamic-topographic interactions on the seamounts could benefit CWCs by maximizing food supply. However, changes at finer scales in terrain morphology and bottom salinity were important for driving differences in the distribution of specific CWCs. The ensemble model predicted the presence of VME taxa on all seamounts and consistently achieved the highest performance metrics, outperforming individual models. Nonetheless, model extrapolation and uncertainty, measured as the coefficient of variation, were high, particularly, in least surveyed areas across seamounts, highlighting the need to collect more data in future surveys.Main ConclusionsOur study shows how data-poor areas may be assessed for the likelihood of VMEs and provides important information to guide future research in Cabo Verde, which is fundamental to advise ongoing conservation planning. ObjetivoMontes submarinos s & atilde;o importantes forma & ccedil;& otilde;es geol & oacute;gicas com um not & aacute;vel papel ecol & oacute;gico e podem ser considerados Ecossistemas Marinhos Vulner & aacute;veis (VMEs). Dado que muitas regi & otilde;es do mar profundo permanecem inexploradas, investigar a ocorr & ecirc;ncia de esp & eacute;cies indicadoras de VMEs & eacute; um desafio. O nosso estudo teve como objetivo prever a distribui & ccedil;& atilde;o de quatro taxa de corais de & aacute;gua fria (CWC), indicadores de VMEs, numa regi & atilde;o onde dados de ocorr & ecirc;ncia s & atilde;o escassos.Localiza & ccedil;& atilde;oMontes submarinos no Arquip & eacute;lago de Cabo Verde (NO & Aacute;frica).M & eacute;todosUtilizamos dados de presen & ccedil;a-aus & ecirc;ncia de CWC obtidos a partir de imagens de um Ve & iacute;culo de Opera & ccedil;& atilde;o Remota (ROV) durante duas expedi & ccedil;& otilde;es cient & iacute;ficas. Como dados ambientais foram utilizados vari & aacute;veis de terreno calculadas com uma abordagem multi-escala a partir de uma grelha de batimetria com 100 m de resolu & ccedil;& atilde;o, e dados de oceanografia f & iacute;sica obtidos com o modelo VIKING20X, a uma resolu & ccedil;& atilde;o nativa de 1/20 degrees. Duas t & eacute;cnicas de modela & ccedil;& atilde;o (Generalized Additive Models (GAM) e Random Forest) foram usadas e resultados de modelos individuais foram combinados, atrav & eacute;s da m & eacute;dia ponderada, num modelo final Ensemble. O desempenho dos modelos foi validado usando diferentes m & eacute;tricas atrav & eacute;s de t & eacute;cnicas de valida & ccedil;& atilde;o cruzada.ResultadosA orienta & ccedil;& atilde;o do terreno, a larga escala, apresentou uma das maiores contribui & ccedil;& otilde;es relativas para os modelos de distribui & ccedil;& atilde;o de todos os CWCs, sugerindo que intera & ccedil;& otilde;es de hidrodin & acirc;mica com topografia beneficiam os corais, possivelmente pelo aumento da disponibilidade de alimento. No entanto, mudan & ccedil;as na morfologia de terreno a escalas mais finas e salinidade foram importantes para diferen & ccedil;as entre a distribui & ccedil;& atilde;o de esp & eacute;cies espec & iacute;ficas. O modelo Ensemble projetou a presen & ccedil;a de indicadores de VMEs em todos os montes submarinos e, consistentemente, apresentou m & eacute;tricas de desempenho mais altas, superando modelos individuais. No entanto, medidas de extrapola & ccedil;& atilde;o e incerteza foram elevadas, especialmente em & aacute;reas menos estudadas, destacando claramente a necessidade de recolher mais dados.Conclus & atilde;oO nosso estudo mostra como & aacute;reas com poucos dados podem ser avaliadas quanto & agrave; probabilidade de VMEs e fornece informa & ccedil;& otilde;es importantes para guiar futuras investiga & ccedil;& otilde;es em Cabo Verde, sendo fundamental para aconselhar planos de conserva & ccedil;& atilde;o em curso.

Abstract We compile an extensive catalog comprising geochemistry and ages of Cenozoic volcanic provinces in the Mediterranean region, distinguishing between three groups according to the geochemistry of magmatic rocks: intraplate (IVP), subduction‐related (SRVP), and mixed‐origin volcanic provinces (MVP; intraplate with subduction imprint). In order to relate their spatial distribution to properties of the lithosphere‐asthenosphere system, we determine temperature‐depth profiles by integrated geophysical‐petrological inversion at representative locations, using Rayleigh and Love wave phase velocities, heat flow, rock densities, and accounting for thermochemical conditions. The results confirm the occurrence of thin lithosphere (<100 km) above warm asthenosphere (>1,300°C) in areas of low shear‐wave velocities in the shallow upper mantle. Nine shallow asthenospheric volumes (SAVs) between 70 and 300 km depths are identified, forming a partly interconnected belt across the Circum‐Mediterranean. A remarkable colocation exists between the SAVs and the intraplate and mixed‐origin volcanic provinces (IMVPs). Whereas dense networks of IMVPs have formed above the SAVs, IMVPs are absent in areas of thick mantle lithosphere. Magmatic activity in IMVPs at 60–70 Ma indicates that several SAVs existed already in the Paleogene (Central European, Adriatic, Western Mediterranean, and Moesian SAVs). The formation of SAVs is related either to asthenospheric upwelling caused by slab rollback and back‐arc extension (Aegean‐Anatolian, Moesian, Pannonian, Western Mediterranean SAVs), or to thermal upwelling (Adriatic, Central European, Middle East [MEA], North African, Rhine‐Rhone SAVs), with some of the latter coupled partly with continental rifting (Central European, MEA, North African, Rhine Rhone SAVs).

AbstractThe Cabo Verde Archipelago is related to a mantle plume located close to the rotational pole of the African Plate. It consists of islands and seamounts arranged in a horseshoe‐shaped pattern open to the west, thus forming two volcanic chains, each with a weak east‐west age progression. High‐resolution swath bathymetry of 12 Cabo Verde seamounts is used here to assign each seamount to its pre‐shield, shield or post‐shield evolutionary stage, respectively. The eastern seamounts exhibit degraded and partially eroded morphologies, and are mainly in their post‐shield stage. A new 40Ar‐39Ar date for Senghor Seamount at 14.872 ± 0.027 Ma supports old ages for the eastern seamounts. The western seamounts generally exhibit younger volcanic‐edifice‐construction morphologies, showing fresh effusive and explosive volcanics, including rarely observed deep‐water explosive volcanism in the Charles Darwin Volcanic Field. Furthermore, the two previously unknown seamounts Sodade and Tavares in the westernmost termini of both volcanic chains exhibit pristine volcanic morphologies, in agreement with present‐day volcanism and seismic activity recorded from the western seamounts. The islands and seamounts rest on three submarine platforms to the east, northwest and southwest, respectively. Taken together, the seamount and island data suggest a shift in igneous activity from the eastern to the other platforms at about 8–6 Ma. However, the complex evolution pattern for both volcanic chains includes the simultaneous occurrence of pre‐shield or shield edifices at any time, followed by erosional and rejuvenation stages. The new seamount data still demonstrate ongoing westward submarine‐growth in both volcanic chains.

ABSTRACT Severe storm flooding poses a major hazard to the coasts of north‐western Europe. However, the long‐term recurrence patterns of extreme coastal flooding and their governing factors are poorly understood. Therefore, high‐resolution sedimentary records of past North Atlantic storm flooding are required. This multi‐proxy study reconstructs storm‐induced overwash processes from coastal lake sediments on the Shetland Islands using grain‐size and geochemical data, and the re‐analysis of historical data. The chronostratigraphy is based on Bayesian age–depth modelling using accelerator mass spectrometry 14 C and 137 Cs data. A high XRF‐based Si/Ti ratio and the unimodal grain‐size distribution link the sand layers to the beach and thus storm‐induced overwash events. Periods with more frequent storm flooding occurred 980–1050, 1150–1300, 1450–1550, 1820–1900 and 1950–2000 ce, which is largely consistent with a positive North Atlantic Oscillation mode. The Little Ice Age (1400–1850 ce ) shows a gap of major sand layers suggesting a southward shift of storm tracks and a seasonal variance with more storm floods in spring and autumn. Warmer phases shifted winter storm tracks towards the north‐east Atlantic, indicating a possible trend for future storm‐track changes and increased storm flooding in the northern North Sea region.

Plutonic xenoliths from volcanic arcs provide unique insights into transcrustal magmatic systems in subduction zone settings. At Santorini volcano in the Central Aegean Volcanic Arc (Greece), plutonic xenoliths occur throughout a sequence of lavas and pyroclastic rocks erupted within the last ~360 ka. They are mineralogically variable, ranging from troctolites to olivine gabbros, gabbros, gabbronorites, and diorites. Thermobarometric calculations based on mineral and melt inclusion compositions indicate equilibration over a range of temperatures (1100 to 750 °C) at shallow to mid-crustal depths (P <400 MPa), but there is no evidence for crystallisation at lower crustal depths. Oxygen isotope data of mineral separates and calculated δ18O melt values are in line with extensive closed-system fractional crystallisation at magmatic temperatures, without a requirement for extensive assimilation of the subvolcanic continental basement. The xenolith minerals compositionally overlap with phenocrysts from the volcanic rocks, but they also contain evidence for the presence of highly evolved melt compositions in the form of melt inclusions with extremely silica-rich compositions (up to 82 wt.% SiO2) and high enrichments of incompatible trace elements coupled with increasing negative Eu anomalies in clinopyroxenes. Since these characteristics correlate systematically with differentiation indices and rock type, they are interpreted to reflect melt evolution via fractional crystallisation as the dominant differentiation process with no significant role of reactive porous flow. These observations highlight that trapped melt fractions can influence mineral compositional variations in the plutonic xenoliths, and in turn the mineral compositions demonstrate a melt compositional variability not preserved in the volcanic rock record.

The volcanic history of Mt. Etna is mainly known from studies of subaerial deposits and stratigraphy. However, little is known about the offshore deposits, which can provide a more detailed insight into geological and sedimentological processes affecting the flanks of Mt. Etna. During RV Meteor Cruise M178, eight gravity cores were taken offshore across the continental margin east of the volcanic edifice to re-evaluate the volcanic history of pre-historic eruptions and mass wasting events in the area. In total, we investigated 87 marine tephra layers in order to build a marine tephrostratigraphic framework. Based on major element compositions of glass shards, sediment componentry, and petrographic characteristics, 27 layers were identified as primary pyroclastic flow and fall deposits, i.e., directly related to an explosive volcanic eruption. However, most of the remaining tephra layers are interpreted to represent deposits of secondary density currents and are not necessarily related to a volcanic eruption. The marine dataset is complemented by twelve onshore samples taken from major explosive eruptions. Applying geochemical fingerprinting of volcanic glass shard compositions, we correlated eleven marine tephra deposits to seven well-known Mt. Etna eruptions (FV, FF, FG, FL, FS, TV, and M1 eruptions) within the last 12 kyr, which provide valuable time markers in the marine sediment record. Furthermore, we correlated ten marine tephra layers between the marine cores (four individual eruptions) and identified another six primary layers in single cores. In total, we discovered 17 widespread volcanic events in the marine record, including four previously unknown eruptions between 10 and 7.7 ka, which indicate that Mt. Etna was more active than previously thought during this time period.

Recent studies on oceanic transform faults, one of the three fundamental types of plate boundaries, has suggested that they may not be purely conservative features and that the crust formed adjacent to them (on the "inside corners" of the ridge-transform intersection) may differ in structure and composition significantly from outside-corner crust. Here we present a geological map of the Oceanographer Transform (Atlantic Ocean, southwest of the Azores) created by combining an interpretation of multibeam bathymetry, rock sampling and seafloor visual observations. We find that outside- and inside-corner crust at the ridge transform intersection have distinctive morphologies and petrography: the outside corner shows rough seafloor, from which only pillow basalts are recovered, extending all the way to the fracture zone. The inside corners, in contrast, are characterized by both rough, basaltic seafloor and regions that are much smoother, from which serpentinized peridotite are often recovered. The width of the inside-corner region showing this variable morphology, bathymetry and petrography seems to vary over time from 10 to 25 km. In two places, oceanic core complex crust is recognized close to the transform in this inside-corner region. We emphasize that plate production at the inside corner appears to occur via a variety of magmatic and amagmatic processes.

Volcanic islands export clastic material to their surrounding oceans by explosive eruptions, lava emissions, biogenic production on their shelves, and failure of their slopes, amongst other processes. This raises the question of whether geological events (in particular, eruptions and landslides) can be detected offshore and dated, and whether any relationships (for example, with climate changes) can be revealed using sediment cores. The volcanically active central Azorean islands (Faial, Pico, Sao Jorge, and Terceira), with their neighboring submarine basins, are potentially good candidates for such an analysis. Here, chronostratigraphies of four gravity cores collected amongst the islands are constructed based on twelve radiocarbon dates and two dates derived by geochemically correlating primary volcaniclastic turbidites with ignimbrites on Faial and Terceira Islands. Age-depth models are built from the hemipelagic intervals to estimate individual turbidite dates. Volumes of turbidites are modeled by multiplying basin areas with bed thickness, allowing for various turbidite thinning rates and directions. The volumes of landslide-generated turbidites are only comparable with the largest volumes of their adjacent upper-slope submarine landslide valleys; therefore, such turbidites in the cores likely derive from these largest landslides. Emplacement intervals between turbidites originating from both landslides and pyroclastic density currents are found to be mostly a few thousand years. Frequencies of landslide-generated turbidites and hemipelagic sedimentation rates were both highest in the past 8 k.y. compared to preceding periods up to 50 k.y. High hemipelagic sedimentation rates are interpreted to be related to sea-level rise, allowing more shelf bioproduction and release of particles by coastal erosion. The coincident increased frequencies of submarine landslides may also be associated with the increased sediment supply from the islands, resulting in a more rapid build-up of unstable sediments on submarine slopes. Notably, the emplacement frequencies of turbidites of pyroclastic density current origins do not suggest the decreased eruption frequency toward the Holocene that has been found elsewhere.

Abstract Volcanic eruptions can trigger tsunamis, which may cause significant damage to coastal communities and infrastructure. Tsunami generation during volcanic eruptions is complex and often due to a combination of processes. The 1650 eruption of the Kolumbo submarine volcano triggered a tsunami causing major destruction on surrounding islands in the Aegean Sea. However, the source mechanisms behind the tsunami have been disputed due to difficulties in sampling and imaging submarine volcanoes. Here we show, based on three-dimensional seismic data, that ~1.2 km³ of Kolumbo’s northwestern flank moved 500–1000 m downslope along a basal detachment surface. This movement is consistent with depressurization of the magma feeding system, causing a catastrophic explosion. Numerical tsunami simulations indicate that only the combination of flank movement followed by an explosive eruption can explain historical eyewitness accounts. This cascading sequence of natural hazards suggests that assessing submarine flank movements is critical for early warning of volcanogenic tsunamis.