Search Results (156)

Tsunami hazards in the Bay of Naples are primarily driven by submarine landslides, intense seismic activity, and volcanic phenomena from nearby systems like Vesuvius and the Campi Flegrei caldera. While localized historical tsunamis have occurred, they are generally rare events. Key tsunami sources include submarine landslides, volcanic eruptions, and seismicity. In this paper we provide a review of the tsunamis in Naples Bay within a general framework of Mediterranean tsunamis based on a literature review. Underwater avalanches, particularly around the steep slopes of the Dohrn Canyon and Ischia, are considered a primary localized threat. Scientific models indicate that a major collapse (like past events like the Ischia debris avalanche) could generate significant waves that could cross the bay in minutes. Explosive eruptions where magma meets seawater (such as PDCs—pyroclastic density currents) can displace water violently. This was famously documented during the AD 79 eruption of Mount Vesuvius, which created submarine ash fans and tsunami waves in the gulf. Earthquakes related to bradyseism in the Campi Flegrei or regional faults can also trigger sea level oscillations or localized tidal waves. Among the historical modeled events, we focus on the A.D. 79 eruption and on the 1343 Naples tsunami. The numerical simulations are revised. Depending on the source, the modeled waves vary from minor oscillations to heights of up to 6 m in canyon areas or over 20 m in nearby islands like Ischia. Full article

Papua New Guinea (PNG) remains one of the least studied regions in the Southwest Pacific, and the tectono-magmatic evolution of extensive areas such as the Fly Platform remains poorly constrained. This study presents the first investigation of basaltic volcanism on the Fly Platform based on the discovery of two previously unrecognized volcanic centres, Meahill and Yemsigi, located approximately 13 km apart along a northeast–southwest alignment. Integrated field observations and petrographic studies reveal contrasting eruptive and emplacement histories. Yemsigi is characterized by coherent porphyritic basalts, whereas Meahill comprises highly vesicular porphyritic to micro-porphyritic basalts indicative of explosive volcanism. Mineral chemistry and whole-rock geochemistry indicate that both basalt suites were derived from a common magma source. The K–Ar age of 0.57 ± 0.09 Ma for the Meahill basalts suggests that volcanism on the Fly Platform represents a late-stage magmatic event that post-dates the Maramuni Arc and Central Highlands magmatism on the PNG mainland. These findings provide the first evidence for Middle Pleistocene volcanism on the Fly Platform and place new constraints on the tectono-magmatic evolution of southern PNG. Full article

Accurate classification of infrasound signals is essential for nuclear-test verification, natural-hazard warning, and geophysical monitoring. Conventional convolutional neural networks (CNN) applied to this task tend to overfit small, class-imbalanced datasets and cannot quantify predictive uncertainty. To address these limitations, we introduce a Bayesian CNN framework that treats network weights as probability distributions and performs inference by variational approximation. LeNet-5, AlexNet, and 4Conv3Fc network serve as baselines and are converted into Bayes LeNet-5, Bayes AlexNet, and Bayes 4Conv3Fc. The short-time Fourier transform (STFT) provides time–frequency spectrograms as model input. On a highly imbalanced dataset comprising nuclear tests, chemical explosions, volcanic eruptions, rocket launches, earthquakes, and lightning, Bayes 4Conv3Fc reaches an overall accuracy of 99.14% without any data augmentation. Relative to the deterministic baselines, precision, recall, and F1-score increase by up to 6.91, 7.12, and 7.20 percentage points, respectively, and Cohen’s Kappa coefficient by up to 8.86 percentage points. Against class-weighted cross-entropy, a standard imbalance-handling baseline, the Bayesian models yield consistently lower Brier scores, indicating that the gains stem from principled uncertainty modelling rather than loss re-weighting alone.. This study quantifies both epistemic and aleatoric uncertainty in an infrasound signal classification model, and the calibration analysis validates that these uncertainty estimates are reliable, providing a basis for evaluating prediction reliability and diagnosing potential failure modes, thereby contributing to improved model interpretability. Coupled with an event-level data partitioning strategy, the evaluation faithfully reflects the model’s generalization to unseen events and offers a promising direction toward uncertainty-aware infrasound monitoring. Full article

The Arteni volcanic complex (Armenia) represents a distinctive volcanic landscape characterized by well-preserved pyroclastic deposits, rhyolitic domes, extensive obsidian flows, and significant archaeological evidence. This study aims to evaluate the geoheritage value of the complex and to develop a scientifically grounded geotouristic trail model based on the targeted selection of representative sites. Field-based investigations were integrated with a simplified semi-quantitative assessment of selected sites and Geographic Information System (GIS)-supported spatial analysis, including topographic, viewshed, and accessibility analyses. The results allowed for the selection of nine representative sites, effectively representing the principal stages of volcanic evolution, including explosive eruptions, lava flow emplacement, and dome formation. Spatial analysis demonstrates that the selected sites enable the development of a coherent, accessible, and scientifically meaningful geotouristic route while balancing scientific representativeness with visitor accessibility and safety. In addition, the widespread occurrence of obsidian and associated archaeological artifacts highlights the combined geological and cultural significance of the area. The proposed approach provides a transferable framework for the development of geotourism in volcanic regions and contributes to geoheritage conservation, geoeducation, and sustainable regional development. Full article

The Santorini volcano attracts global interest. The 17th century BCE Minoan eruption was likely the largest ever occurring in the Holocene. The evaluation of an enriched collection of documentary sources combined with geological observations showed that in historical times, 15 eruption episodes were recorded from the 2nd century BCE up to 1950 CE. Little-known episodes occurring in 1667 CE and 1773 CE were uncovered, analyzed and included in the catalogue. Due to many uncertainties and inconsistencies involved in the historical sources, a reliability score ranging from 1 (lowest) to 4 (highest) has been assigned to each one of the 15 episodes. This procedure was based on a Reliability Assessment Matrix, which is a novelty in historical volcanology. The size of an eruption was evaluated in terms of the 8-grade Volcanic Explosivity Index (VEI) by introducing a bimodal assignment form of “V or V + 1”, an approach used for the first time, instead of the traditional unimodal assignment of “V”. The VEI of 4–5 was assigned to the eruptions of 725/726 CE in the Santorini caldera and of 1650 CE in the Kolumbo submarine volcano. The rest of the eruptions were assigned with smaller VEIs. Completeness analysis of the catalogue with statistical tests and Monte Carlo simulation with random and non-random models as baselines showed a 10-fold increase in the eruption record in 450 years after the breakpoint of 1572 CE eruption compared to the 1747 years before that point implying that there are about 30 missing eruption events that escaped record in the pre-1572 CE historical interval. This statistically significant difference is interpreted as a bias discovery effect of anthropogenic origin, but further research is needed to show that it does not represent a drastic change of magma plumbing rate. Full article

Volcanic ash preserves critical information on eruption dynamics, magma evolution, and fragmentation processes, yet its small size and fragile structure pose challenges for conventional analytical methods. Advances in SEM-based automated mineralogy combined with X-ray mapping (GXMAP) provide high-resolution characterization of ash textures, particle morphology, and mineral assemblages, offering a more robust basis for interpreting pyroclastic deposits. This study applies an integrated GXMAP workflow alongside sieve-based granulometry to the Early Pleistocene trachyandesite to rhyolitic pyroclastic sequences at the Kurtan quarry (Kechut Volcanic Province, Armenia), a key regional stratigraphic marker associated with early human occupation. GXMAP-based granulometry minimizes preparation-induced fragmentation and yields more consistent and reliable grain-size and morphological data for fine ash deposits than dry sieving. The three stratigraphic units at Kurtan display distinct combinations of grain size, mineral assemblages, and particle morphologies, reflecting contrasting magma evolution, fragmentation conditions, and depositional regimes. Shape-parameter fields derived from BSE images reveal clear differences between the highly irregular, concave compound fragments dominating TP-13-1 and the smoother, more compact particles characteristic of TP-13-2 and TP-13-3. Most particles fall within the ductile domain of established shape-morphology diagrams, indicating that ductile deformation of bubble walls was a major component of fragmentation, accompanied by heterogeneous brittle breakage. These results demonstrate the effectiveness of the combined SEM-based automated mineralogy and GXMAP approach for resolving primary fragmentation, sorting characteristics, and depositional processes in fragile pyroclastic deposits. The Kurtan sequence provides new constraints on explosive volcanism in the Lesser Caucasus Mts. region. At the same time, the methodological framework offers broad applicability to tephra studies worldwide and underscores the potential of imaging-based techniques in volcanology. Full article

Continental rift lacustrine basins typically feature multiple sediment sources under the combined controls of volcanism, tectonics, water balance and sediment supply, resulting in complex stratigraphic successions. This complexity is particularly pronounced in fine-grained successions, which are of high interest for their potential to generate and accumulate hydrocarbons. Nevertheless, the mechanisms governing the sedimentary transition from volcaniclastic to siliciclastic-dominated fills within a rift cycle remain poorly constrained. The Lower Cretaceous Xiguayuan Formation in the Luanping Basin accumulated in a lacustrine setting influenced by explosive volcanism, providing an excellent archive of siliciclastic–volcaniclastic interaction. Based on field observations, core descriptions, and petrographic analysis, sixteen lithofacies have been grouped into seven facies associations, including subaqueous ignimbrite, volcanically sourced turbidites, subaqueous volcanic ridge, central-lake sedimentation, shallow-lacustrine margin deposits, low-density turbidites, and high-density turbidites. Their spatial relationships reveal two volcanic pulses and document the lake’s environmental evolution, with deep-water background sediments overlying volcaniclastics and a marked increase in siliciclastic input upsection, reflecting a transition from an underfilled, volcaniclastic-dominated underfilled lake to a siliciclastic-dominated lake. Notably, the fine-grained sediments associated with volcanism exhibit excellent hydrocarbon potential. Organic-rich claystones and carbonate laminae form a microscopic source–reservoir system, in which volcanic inputs appear to enhance organic matter preservation and promote the development of reservoir-quality layers. This study elucidates how volcanic activity modulates sedimentation and sediment supply in a deep-lacustrine rift, offering new insights into volcano-sedimentary interactions and related hydrocarbon systems in continental rift basins. Full article

Lunar dark mantle deposits (DMDs), formed by explosive volcanic activity on the Moon, are typically composed of glass- and iron-rich pyroclastic materials, with slight variations in color, crystallinity, and TiO₂ concentration by region. This paper proposes a method for identifying DMDs using the YOLOv8 deep learning model, enhanced by the introduction of a multi-scale feature extraction (MSFE) module with an attention mechanism, which improves the model’s ability to detect targets at different scales. First, a DMD dataset was constructed using Lunar Reconnaissance Orbiter (LRO) data, with manual annotations of DMD regions and lunar image slicing to optimize computational efficiency. The YOLOv8 architecture, with the incorporated MSFE module, was then used to improve model accuracy in complex terrain. The experimental results showed that the improved DM-YOLO model achieved a precision (P) of 83.9%, a recall (R) of 83.2%, and a mean average precision (mAP@0.5) of 84.2%, representing increases of 15.2%, 14.4%, and 14.0%, respectively, over those obtained with the original YOLOv8 model. The predicted results were preliminarily verified using FeO abundance data and further confirmed by analysis of M³ spectral absorption features, showing strong consistency with known DMDs in terms of both chemical composition and mineralogical characteristics. Observations showed that DMDs were located primarily in the low- and mid-latitude regions of the Moon, with most deposits found in the lunar highlands. The findings suggest that the DM-YOLO model has significant potential for providing technical support for lunar exploration and resource development, particularly for identifying small-scale features that are difficult to annotate. Full article

Stromboli’s volcanic activity fluctuates in intensity and style, and periods of heightened activity can trigger hazardous events such as crater collapses and lava overflows. This study investigates the volcano’s explosive behavior surrounding the 19 May 2021 crater-rim failure, which primarily affected the N2 crater and partially involved N1, by integrating high-frequency thermal imaging and high-resolution unmanned aerial system (UAS) surveys to quantify eruption parameters and vent morphology. Typically, eruptive periods preceding vent instability are characterized by evident changes in geophysical parameters and by intensified explosive activity. This is quantitatively monitored mainly through explosion frequency, while other eruption parameters are assessed qualitatively and sporadically. Our results show that, in addition to explosion rate, the spattering rate, the predominance of bomb- and gas-rich explosions, and the number of active vents increased prior to the collapse, reflecting near-surface magma pressurization. UAS surveys revealed that the pre-collapse configuration of the northern craters contributed to structural vulnerability, while post-collapse vent realignment reflected magma’s adaptation to evolving stress conditions. The May 2021 events were likely influenced by morphological changes induced by the 2019 paroxysms, which increased collapse frequency and amplified the 2021 failure. These findings highlight the importance of integrating quantitative time series of multiple eruption parameters and high-frequency morphological surveys into monitoring frameworks to improve early detection of system disequilibrium and enhance hazard assessment at Stromboli and similar volcanic systems. Full article

Explosive volcanic eruptions are key drivers of climate variability, yet their hemispheric-dependent impacts remain uncertain. Using multi-model ensembles from Coupled Model Intercomparison Project Phase 6 (CMIP6) historical data and Decadal Climate Prediction Project (DCPP) simulations, this study examines how the spatial distribution of volcanic aerosols modulates climate responses to Northern Hemisphere (NH), Tropical (TR), and Southern Hemisphere (SH) eruptions. The CMIP6 ensemble captures observed temperature and precipitation patterns, providing a robust basis for assessing volcanic effects. The results show that the hemispheric distribution of aerosols strongly controls radiative forcing, surface air temperature, and hydrological responses. TR eruptions cause nearly symmetric cooling and widespread tropical rainfall reduction, while NH and SH eruptions produce asymmetric temperature anomalies and clear Intertropical Convergence Zone (ITCZ) displacements away from the perturbed hemisphere. The vertical temperature structure, characterized by stratospheric warming and tropospheric cooling, further amplifies hemispheric contrasts through enhanced cross-equatorial energy transport and shifts in the Hadley circulation. ENSO-like responses depend on eruption latitude, TR and NH eruptions favor El Niño–like warming through westerly wind anomalies and Bjerknes feedback, and SH eruptions induce La Niña–like cooling. The DCPP experiments confirm that these signals primarily arise from volcanic forcing rather than internal variability. These findings highlight the critical role of aerosol asymmetry and vertical temperature structure in shaping post-eruption climate patterns and advancing the understanding of volcanic–climate interactions. Full article

This work presents an automated method for detecting and monitoring volcanic islands in the Tonga archipelago using Sentinel-2 satellite imagery. The method is able to detect newly created islands, as well as an increase in island size, a possible precursor to an explosion due to magma chamber inflation. At its core, the method combines a U-Net-type convolutional neural network (CNN) for semantic segmentation with a custom change detection algorithm, enabling the identification of land–water boundaries and the tracking of volcanic island dynamics. The algorithm analyzes morphological changes through image comparison and Intersection over Union (IoU), capturing the emergence, disappearance, and evolution of volcanic islands. The segmentation model, trained on a custom dataset of Pacific Ocean imagery, achieved an IoU score of 97.36% on the primary test dataset and 83.54% on a subset of challenging cases involving small, recently formed volcanic islands. Generalization capability was validated using the SNOWED dataset, where the segmentation model attained an IoU of 81.02%. Applied to recent volcanic events, the workflow successfully detected changes in island morphology and provided time-series analyses. Practical feasibility of the methodology was assessed by testing it on a large region in Tonga, using an HPC cluster. This system offers potential applications for geophysical studies and navigation safety in volcanically active regions. Full article

Mt. Etna is the highest and most active stratovolcano in Europe, located in Catania (Sicily, Italy). Its persistent degassing, frequent explosions, and lava flows release large amounts of ash and gases into the atmosphere. This study aimed to assess whether chronic exposure to local volcanic emissions leads to an increased internal dose of trace elements (As, Ba, Be, Bi, Cd, Co, Cr, Cu, Hg, Li, Mn, Mo, Ni, Pb, Sb, Se, Sn, Sr, Tl, U, V, W, Zn) in Catania adult residents. To this end, urine samples were collected from 167 individuals residing in Catania and compared with 193 residents of other Sicilian areas located farther from the volcano. Results revealed significantly higher urinary concentrations of As, Hg, Mn, Pb, and Tl in the exposed group, suggesting volcanic activity as a relevant source of exposure. The levels of the other elements were instead affected by other factors such as lifestyle habits and the consumption of specific foods and beverages. The urinary concentrations of trace elements were consistent with reference values reported in other European studies, and the levels remained well within the health-based guidance values. There is evidence of an increased internal dose of a few elements in the Sicilian population exposed to volcano activity, but the observed increases are unlikely to pose a significant health risk. Full article

Volcanic crater interiors in Nicaragua’s Pacific region are a valuable, understudied, and threatened native plant resource. Laguna de Apoyo Nature Reserve encompasses a crater and lake formed following a Quaternary volcanic explosion in Pacific Nicaragua. The flora of the tropical dry forest in the crater’s interior surrounding the lake has not been extensively assessed. We identified 403 native and 72 introduced plant species and their uses through a combination of survey plots, unstructured interviews, expert consultations, and targeted searches for plant species coordinated with key informants in the Reserve. Fabaceae, Euphorbiaceae, and Asteraceae were the most represented native species, whereas the most significant numbers of introduced species were found in Poaceae, Euphorbiaceae, and Fabaceae. Forty-one species have conservation priority status. Documented uses were found for 70% of the native species and 88% of the introduced species. The most significant numbers of plant species with reported use types were ornamentals and fuelwood. This study constitutes the most comprehensive plant species inventory in a protected area of Nicaragua’s tropical dry forest biome. These findings indicate native plant diversity is high, introduced species pose considerable risks, and most species are integrated into local uses. Consequently, management decisions should explicitly promote native diversity, protect threatened species, better control introduced species, and encourage sustainable use. Full article

The Santorini volcano in the South Aegean Volcanic Arc is of great scientific importance. Knowledge of historical eruptions is valuable for better understanding the volcanic cycle and for improved hazard assessments. One of the little-known historical eruptions occurred either in 1570 or in 1573 or from 1570 to 1573 CE. We bring to light a very little-known but reliable Greek manuscript dated in 1588 CE which improves our knowledge about this eruption. The manuscript documents that the eruption occurred in 1572 and took place within the sea caldera between Santorini and Palaia Kameni. It makes it clear that “fire, smoke, and stones” were coming out between the two islands and a new volcanic island named Mikri Kameni was born. This landscape has been verified by independent maps of the 17th and 18th centuries. The floating pumice was transported by the sea as far as to Thessaloniki and Constantinople. Also, we learn a lot about the consequences of the eruption: (1) smoke and heat destroyed the vineyards and the planting season on Santorini, i.e., spring–summer, (2) it is likely that sulfurous gases were released, and (3) the residents of Santorini were forced to move to nearby islands. The duration of the eruption was ~1 year, but the fire and smoke disappeared suddenly. The Volcanic Explosivity Index of the eruption was estimated to be as high as 3. Full article

Chemical mixing of different types of magma, such as basaltic magma and silica-rich, hydrous magma, often triggers volcanic eruptions. However, the kinetics, mechanisms, and rates of sulfide dissolution reactions in hydrous melts are currently unknown, despite the fact that these reactions can influence the sulfur budget in the crust and mantle. I experimentally model dissolution of pyrrhotite minerals in hydrous rhyolite melt at conditions corresponding to the sulfate–sulfide transition field at 1 GPa pressure. The reaction results in the production of FeO, SO₄²⁻, H₂, H₂S and di- and tri-sulfur radical ions, (S₂⁻ or S₃⁻) in fluid/melt. The calculated sulfur diffusion coefficient implies extremely fast sulfur diffusion in the hydrous hybrid melt. The production of S-rich magma is controlled by the fastest-ever-recorded chemical diffusion of sulfur in the form of S₂⁻ or S₃⁻ in hybrid magma under sulfate-sulfide transition conditions. I demonstrate that such dissolution reactions can be responsible for triggering explosive volcanic eruptions (e.g., the 1991 Mount Pinatubo eruption) in volcanic arc settings. The sulfide dissolution reaction can also promote the production of chalcophile metal (sulfur-loving Au, Cu and Pt) ore deposits associated with the formation of volcanic arcs. Full article