Cryptotephra fingerprinting is the most robust method for linking volcanic sulfate deposits in polar ice cores with their eruptive source. Advances in the detection and geochemical characterization of extremely fine cryptotephra deposits (e.g., volcanic glass shards <10 μm in size) have enabled the source identification of increasingly distal eruptions preserved in Greenland and Antarctic cores. These developments improve constraints on eruption timing, sulfur loading, and ash dispersal, allowing reconstruction of detailed volcanic histories assessing the provenance and recurrence rate of events with global, societal consequences.

Here, we investigate evidence for volcanic eruptions occurring during the interval 680-690 CE, preserved in Greenland ice core Tunu2013, and Antarctic ice core B53. This targeted time period includes the 5^th largest volcanic stratospheric sulfur injection of the Common Era (last 2000 years), deposited as a contemporaneous sulfur peak in both hemispheres in 682 CE. Previous hypotheses have suggested three closely timed VEI 5-6 eruptions from New Britain Island, Papua New Guinea, as the most likely source candidates for this sulfur deposit.

By combining cryptotephra geochemical fingerprinting with sulfur isotope analysis, we provide new insights into the sources, plume height, sulfur emission and tephra transport of major eruptions occurring between 680-690 CE, including the 682 CE event and the Newberry Pumice 687 CE eruption. These results contribute to ongoing efforts to identify the sources of the largest Common Era sulfur deposits in polar ice cores and build detailed records of volcanic eruptions associated with global climate perturbations and ultra-distal ash dispersal.

How to cite: Innes, H., Hutchison, W., Firth, C., McConnell, J. R., Chellman, N. J., Blong, R., Jenkins, S. F., Sigl, M., Jensen, B. J. L., Neall, V., and Burke, A.: New ice core insights into the sources and sulfur emission of the largest Common Era eruptions: a case study of eruptions from 680-690 CE, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18473, https://doi.org/10.5194/egusphere-egu26-18473, 2026.

In 2021, 25 sediment cores were gathered in the proximal region of Mayotte Island, in the Comoros Archipelago. A total of ~300 meters was retrieved shedding light into the past volcanic activity of the island, but also of the submarine Eastern Mayotte Volcanic Chain (EMVC) discovered in 2019. By investigating the sediment cores, up to 1 cm resolution scale in the uppermost sedimentary sequence of core MAY15-CS02, we underlined the presence of abundant, fresh, cryptotephra witnessing recent explosive activity from ~2 to 6.5 ka, and a major event at 7.5 ka that could either originate from Petite-Terre or the submarine Horseshoe volcano ^[1]. We also identified new submarine explosive eruptions of phonolitic composition, marked by high-alkali contents, which differs from the most recent activity of Petite-Terre and the Horseshoe ^[2]. A 1-meter-thick deposit dated at around 300 ka presents a less evolved composition than the aforementioned eruptions, and coarser material up to several centimetres scale composed this deposit, shedding light on another major volcanic event that affected Mayotte. Using high-resolution x-ray tomography 3D scans and geochemical analyses together with textural observations, we investigate its origin (subaerial vs. submarine) and emplacement mechanisms, and fine tune Mayotte volcanic history. We present here the key results of this investigation and emphasize the importance of analysing, at a high resolution, proximal (≤5 km from the island coast) sediment cores as they do contain crucial information retrieved from volcanic-related deposits, tephra and cryptotephra to comprehend the overall activity that shaped an island.

^[1] Lebas et al. 2024. IAVCEI-COT abstract, Catania.
^[2] Baudry et al. 2025. IAVCEI abstract, Geneva.

How to cite: Lebas, E., Besson, E., Falvard, S., Gurioli, L., Jouet, G., and Paris, R.: Deciphering the origin and emplacement mechanisms of Mayotte submarine and subaerial volcaniclastic deposits using x-ray tomography and geochemical fingerprinting, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-23073, https://doi.org/10.5194/egusphere-egu26-23073, 2026.

Pyroclastic density currents are among the most fatal events associated with volcanic hazards. When pyroclastic density currents escape their confining channels and become unconfined, then they inundate the inhabited areas and destroy everything in their path. Pyroclastic density currents (PDCs) are hot mixtures of volcanic rock and gases that can flow long distances at velocities of tens to hundreds of kilometers per hour from the source.  PDCs are complex volcanic flows whose dynamics, occurrence, and flow paths are mostly unpredictable. In this project, we are investigating the rheological properties of pyroclastic mixtures sampled from the PDCs’ deposits of the Pollena 472 ACE eruption of Mt. Vesuvius (Italy). First, we characterized the grain size distribution, density, and morphology of the used mixtures, as well as performed BET analysis and Shear cell experiments. Then, using an Anton Paar MCR702e rheometer, we Conduct Shear cell experiments to gain insight into the mobility of the studied granular materials, specifically by measuring their internal friction angle, cohesion (if any), unconfined yield strength, and flowability. In this presentation, I will present preliminary results of all my performed experiments and their implications on the rheology of Pyroclastic Density Currents. 

How to cite: Ammar, M.: Rheological Properties of Pyroclastic Flow Mixtures, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-2465, https://doi.org/10.5194/egusphere-egu26-2465, 2026.

NEVA2 explores the impacts of large explosive volcanic eruptions during the Holocene, with a focus on the southern end of the Central Volcanic Zone (CVZ) of the Andes. These rare but catastrophic events release enormous volumes of pyroclastic material and gases, reshaping landscapes for centuries and influencing the global climate. Despite their significance, the cumulative and cascading effects of these processes on the Earth’s critical zone—the interface of rock, soil, water, air, and life—as well as their role in past climate variability remain insufficiently constrained.

The project targets a unique natural laboratory in Chile and Argentina, where preliminary evidence suggests previously undocumented Holocene eruptions, including a major event at Nevado Tres Cruces volcano around 1,300 years BP (around the 8^th century). This eruption appears to coincide with palaeoclimatic anomalies and cultural changes in pre-Hispanic societies, offering an exceptional opportunity to link geological, environmental, and archaeological records.

NEVA2 aims to identify and date large Holocene eruptions in the southern CVZ, model their dynamics and dispersal using advanced simulation tools, and assess multiscale impacts on the critical zone. It also seeks to correlate eruption timelines with palaeoclimate archives to evaluate associated climatic effects and disseminate findings to scientific communities, stakeholders, and the public.

Combining field surveys, laboratory analyses and modelling approaches, NEVA2 will deliver novel insights into volcanic hazards, provide new Holocene tephrochronological markers for the Southern Hemisphere, and contribute to improved risk mitigation strategies. The project also promotes education and stakeholder engagement to enhance resilience in volcanic regions.

The NEVA2 Project (Ref. ProID2024010012) is funded by the Canary Islands Agency for Research, Innovation and Information Society (ACIISI) and by the European Union under the Canary Islands ERDF Programme 2021–2027. Institutional support was provided by the GEOVOL research group (iUNAT, ULPGC) and Structure and Dynamics of the Earth (Generalitat de Catalunya, 2021 SGR 00413).

How to cite: Fernandez-Turiel, J.-L., Rodriguez-Gonzalez, A., Perez-Torrado, F.-J., Cabrera, M. C., Ratto, N., Polanco, E., Benavente, D., N. García-Martínez, N., and Estevez, E.: The southernmost Central Volcanic Zone of the Andes: a natural laboratory for reconstructing the impact of large explosive Holocene eruptions (NEVA2), EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-2954, https://doi.org/10.5194/egusphere-egu26-2954, 2026.

Particle-laden volcanic flows are hazardous across a wide range of settings, from dispersing ash clouds to pyroclastic density currents (PDCs). Their impacts depend not only on bulk mass loading and particle size, but also on how particles self-organise in space. Yet, many studies and hazard models are built on bulk- or layer-averaged properties, so concentration inhomogeneities within the flow are poorly constrained. A key missing piece is clustering (preferential concentration): particles concentrate into dense regions separated by voids, creating sharp local contrasts that can alter settling, generate short-lived sedimentation pulses, and enhance particle–particle interactions even when mean concentrations are low. We investigate these processes using controlled laboratory experiments that isolate clustering and its effects in sustained, free-falling columns of volcanic ash. We vary particle size distributions and mass release rates to span particle volume fractions ≈10^-5–10^-2, encompassing conditions relevant to dispersing clouds and ash-laden regions within PDCs. High-speed laser imaging and particle tracking resolve instantaneous particle positions and velocities. We quantify clustering with Voronoi tessellation, measure settling velocity variability, and estimate a collision-rate proxy from local particle statistics to link spatial organisation to encounter likelihood. Results suggest that clustering can create strong local concentration contrasts, whose intensity can enhance particle–particle interactions and increase the potential for collisions, aggregation, and turbulence-modulated settling. Importantly, peaks in the collision-rate proxy are not explained by velocity variability alone, indicating that spatial organisation shortens effective interaction length scales and increases encounter frequency. These findings link dilute turbulent suspensions to enhanced fallout and collision/aggregation potential, and they highlight the need for hazard models to capture local concentration contrasts, not just bulk-mean concentrations.

How to cite: Capponi, A., Cimarelli, C., and Mininni, P.: Settling, Swirling, Sticking: Clustering-Driven Interactions In Volcanic Particle Flows, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-5338, https://doi.org/10.5194/egusphere-egu26-5338, 2026.

The first step towards mitigating the risks associated with pyroclastic density currents (PDCs) consists in quantifying the probability of their occurrence through probabilistic hazard studies. The Island of Ischia constitutes the emerged portion of a large volcanic system, known as the Ischia Volcanic Field (IVF). The last eruption, which occurred in AD 1302, was preceded by centuries of intense volcanic activity, with more than 30 eruptions in the last 10,000 years. At present, the Ischia system is quiescent, but new magmatic intrusions could trigger renewed resurgence, seismic activity and slope instability, potentially culminating in volcanism. The island hosts a permanent population of approximately 60,000 inhabitants, which increases dramatically during summer. This demographic context highlights the urgency of quantitatively assessing volcanic hazards on the island, a topic still poorly addressed in the literature. The aim of this work is to quantify the hazard related to the invasion by PDC on Ischia. We adopted two alternative simplified modeling frameworks (the Energy Cone and the Box model) to study all known explosive eruptions of over the past 10 ky. For each eruption we inverted for potential source parameters and investigated their possible correlations. Vent location uncertainty was addressed adopting a kernel approach based on the spatial distribution of active vents during the past 10 ky. By integrating uncertainties in vent location with dimensional variability of currents, we quantified the hazard associated with PDCs both conditionally, given the occurrence of an eruption, and unconditionally, by estimating the probability of invasion within the next century. This analysis provides a first quantitative estimate of the probabilistic hazard associated with pyroclastic flows for Ischia and demonstrates that the highest probabilities are found in densely populated areas, especially in the area of Casamicciola Terme, Ischia Porto, and Barano. Conditional probability of PDC invasion ​​above 5% includes those areas as well as parts of the NW and SW sectors of the island, between Forio, Panza, and Lacco Ameno, including most of the main populated areas.

How to cite: Marfella, D. E., de Vita, S., Macedonio, G., Sansivero, F., and Selva, J.: Probabilistic assessment of hazard related to pyroclastic currents at Ischia, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-5712, https://doi.org/10.5194/egusphere-egu26-5712, 2026.

Pyroclastic Density Currents (PDCs) can be generated by explosive eruptions or by gravitational flank collapses involving unstable volcanic material (e.g., lava fronts, crater rims, domes). While the distribution of block-and-ash flow deposits is topographically confined to the transport and accumulation basin, these phenomena are frequently associated with co-PDC ash clouds. These buoyant clouds, composed of fine particles elutriated from the flow, spread over wider areas and settle as thin fallout layers. The recognition of such widely distributed layers enables the tephrostratigraphic investigation of historical collapse events, which are often under-recorded in the geological record.

At Stromboli, a direct link between pinkish tephra layers and partial flank collapses was established through the observation and syn-emplacement sampling of the ash cloud generated by the 19 May 2021 crater rim collapse (Re et al., 2022). Analogous deposits, previously described in the stratigraphic record (Bertagnini et al., 2011; Rosi et al., 2019; Pistolesi et al., 2020), have been repeatedly observed in recent activity (e.g., July 2024), indicating that such collapses represent a recurrent phenomenon.

Here, we present the study, conducted in the framework of the REFLeCTS project (INGV), of a stratigraphic sequence found on the northern side of the San Bartolo lava flow, dating back to Greek-Roman times (360 BC - 7 AD; Speranza et al., 2008). This succession consists of alternating ash and lapilli fallout beds related to typical Strombolian activity, interspersed with several relatively thick (from few mm to 5 cm) pink ash layers. Given that the limited thickness of these layers and the highly dynamic environment of active volcano flanks usually lead to their rapid obliteration by erosion or burial, the exceptional preservation of these tephra layers offers a unique opportunity to assess the recurrence of flank collapse events during Stromboli's recent eruptive history.

How to cite: Re, G. and Pompilio, M.: Pinkish ash layers as fingerprints of flank instability: Unveiling Stromboli’s collapse recurrence through tephrostratigraphy, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11058, https://doi.org/10.5194/egusphere-egu26-11058, 2026.

Water-laden sedimentary archives, such as marine and lacustrine sequences, have revolutionised the reconstruction of eruptive histories, as they usually hold a richer and more continuous tephra record when compared to subaerial environments. Here, we explore peatlands as another sedimentary archive from which highly detailed tephrostratigraphies can be obtained. Peat sequences have the advantage of being logistically easier and cheaper to access than other water-laden sequences, and more readily amenable to radiocarbon dating than terrestrial sequences. Pico Island in the Azores Archipelago provides an ideal laboratory to test the potential of peatlands as high-resolution sedimentary archives. The island is characterised by numerous basaltic monogenetic cones, yet its tephrostratigraphy remains poorly constrained, as such eruptions typically generate small tephra dispersals, and the resulting deposits are difficult to date. Taking advantage of the ubiquitous peatlands found in the Pico central uplands (above ~600 m altitude), a coring campaign was carried out in July 2025. Eight peatlands were cored using a Russian corer and a UWITEC® piston corer installed on a platform raft. Peatland basins were surveyed using a DJI Mavic 2 drone to produce high-resolution georeferenced digital surface models. Recovered cores were opened and logged at the University of the Azores, where peat, lacustrine, and volcanic facies (tephra horizons) were identified. Loss on ignition (LOI) was determined throughout the sedimentary sequences, and their bases were radiocarbon dated. Here, we present the stratigraphic sequences of the four main peatlands: Caiado and Barreira cone craters, and Peixinho and Lavandeira inter-cone depressions. All four stratigraphic sequences contain numerous tephra horizons, ranging in thickness from less than 1 mm up to several tens of centimetres. The thickest tephra horizons are found at the sites located in the eastern sector (Peixinho and Caiado), whereas thinner horizons predominate at the western sites (Lavandeira and Barreira). Most tephra horizons correspond to primary fall deposits, with only a minor portion of reworked materials. Radiocarbon dating reveals maximum sequence ages of 8608-8514 cal yr BP (Caiado), 6558-6399 cal yr BP (Lavandeira), 5588-5474 cal yr BP (Barreira), and 2181-2046 cal yr BP (Peixinho). The bases of the Barreira and Caiado sequences consist of weathered subaerial scoria deposits, interpreted as pre-lacustrine substrate. Lower LOI values, typically found in the lower part of the sequences, suggest initial lacustrine conditions, whereas higher LOI values in the upper part of the records indicate the transition to peatland. Ongoing work will focus on systematic radiocarbon dating below primary tephra horizons and geochemical characterisation of volcanic glass shards, enabling a high-resolution temporal and spatial reconstruction of Pico’s Holocene eruptive history. This work was supported by Fundação para a Ciência e a Tecnologia (FCT) through project ExTRAP (https://doi.org/10.54499/2023.12382.PEX).

How to cite: Pimentel, A., Souto, M., Raposeiro, P., Ramalho, R., Hernández, A., Andrade, M., Gonçalves, V., Giralt, S., Trigo, R., Matias, M., Schindlbeck-Belo, J., Pacheco, J., and Sáez, A.: Peatlands as high-resolution sedimentary archives of Holocene tephrostratigraphy on Pico Island (Azores): preliminary results, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11883, https://doi.org/10.5194/egusphere-egu26-11883, 2026.

Mount Erciyes, the largest active volcano of Central Anatolia (Turkey), erupted explosively during the Holocene, producing the Karagüllü, Perikartin, and Dikkartin rhyolitic tuff rings. These eruptions occurred along regional fault systems and were partially destroyed by subsequent lava domes at the end of the phreatomagmatic phases, generating block-and-ash flows. Despite the proximity of major urban areas such as Kayseri (~1 million inhabitants), the timing, magnitude, and eruptive sequence of these explosive events have remained poorly constrained, as previous cosmogenic and radiogenic dating attempts lacked sufficient precision to resolve their chronology. To improve the Holocene explosive eruptive history of Mount Erciyes and assess regional ash dispersal, we integrate detailed tephrostratigraphic observations, glass shard geochemistry (major and trace elements), and radiocarbon dating of organic-rich paleosols. Our results indicate that the Karagüllü tuff ring formed at 11,258 ± 56 cal BP, followed by the Perikartin eruption at 9,700 ± 100 cal BP. Although no clear stratigraphic contacts or datable paleosols were identified for Dikkartin, its glass composition closely matches the regional Mediterranean S1 tephra, dated to approximately 9 ka BP. Distal correlations confirm the presence of Karagüllü tephra in the Black Sea tephra and Romanian lake records, indicating that Central Anatolian eruptions dispersed volcanic ash over several hundred to more than a thousand kilometres across Europe and the eastern Mediterranean during the early Holocene. Trace element data further support a distal dispersal of Dikkartin and Perikartin ashes to the Mediterranean basin. While Dikkartin has been classified as a Plinian eruption, the possibility of near-synchronous eruptive activity between Dikkartin and Perikartin cannot be excluded. These results refine the regional tephrochronological framework and underscore the need to reassess volcanic hazards in Central Turkey and surrounding regions.

This work was funded by the Spanish Ministry of Science and Innovation (TURVO, PID2023-147255NB-I00; MCIN/AEI/10.13039/501100011033), the EU (ERDF; Horizon 2020–MSCA PÜSKÜRÜM, Grant 101024337), and the Italian PNRR–NextGenerationEU through the ÇoraDrill project (CUP B83C25001180001).

How to cite: Sunyé-Puchol, I., Özsoy-Ünal, R., Bolós, X., Smith, V. C., Akkas, E., Tavazzani, L., Aymerich, J., Nazzari, M., Lacan, P., Bachmann, O., Scarlato, P., and Mollo, S.: Eruptive history of Holocene explosive activity at Erciyes volcano (Turkey) constrained by proximal and distal tephra records, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11893, https://doi.org/10.5194/egusphere-egu26-11893, 2026.

Electrical activity, including visible lightning, has been observed at Stromboli (Italy) during various eruptive scenarios and has also been reported in association with the emplacement of pyroclastic density currents (PDCs). The multiparametric monitoring network operating at Stromboli enables a detailed investigation of PDCs generated by a range of eruptive and gravitational processes, including column collapse during paroxysmal eruptions, crumbling of lava overflows, and collapses of the crater rim or flank. Previous analyses of the electrical activity at Stromboli have primarily focused on paroxysmal eruptions during which PDCs concurrently occurred, making it difficult to isolate and interpret electrical signatures generated by PDCs alone. PDCs generated by gravitational instabilities of volcaniclastic deposits, located on the crater rim or volcano flanks, offer a unique opportunity to investigate their electrical signatures in the absence of an eruptive column and other relevant syn-explosive processes. Here, we present analyses of electrical signals recorded during the occurrence of deposit-derived PDCs propagating along Sciara del Fuoco. Electrical activity was measured using a lightning detector deployed in close proximity to the flow pathway to monitor changes in the ambient electric field. Complementary thermal and visual imaging of the crater area and flow path enables correlation of the electrical signal variation with the timing, evolution, and spatial extent of the PDC events. We compare these observations with electrical signals recorded during eruptive activity at Stromboli involving sustained eruptive columns, to assess the similarities and differences between column-collapse PDCs and eruption-driven electrical signatures. Distinguishing different types of volcanic phenomena solely based on their electric signature offers a complementary approach for volcano monitoring, enabling the rapid detection of PDC occurrence and aiding the classification of explosive activity.

How to cite: Poetsch, C., Cimarelli, C., Capponi, A., Di Traglia, F., and Bennett, A. J.: Electrical Signals Generated by Pyroclastic Density Currents at Stromboli Volcano, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14159, https://doi.org/10.5194/egusphere-egu26-14159, 2026.

Pyroclastic density currents (PDCs) are mixtures of volcanic particles and gas that flow down the flanks of volcanoes, guided to some degree by the morphology. They are the deadliest and most destructive volcanic phenomena, primarily due to their mobility and unpredictability. Mechanical interaction of clasts during transport produces fines through abrasion and comminution. The ash content is believed to have a positive influence on mobility, however, the in-situ production of ash in PDCs is still poorly quantified.

Three different types of experiments (T1, T2, T3B), each starting with 2 kg angular pumice lapilli from the Laacher See (Eifel, Germany) eruption at 12,900 a BP, were conducted to gain a better understanding of ash production rates and related lapilli clast shape changes (Figueiredo et al., 2025). Every set of experiments eventually tumbled the lapilli for 120 minutes. At five time increments (15’, 30’, 45’, 60’, 120’) the drum load was dry sieved at 2 mm. For T1 experiments, ash and lapilli were returned to the drum after each time step. In experiments T2 and T3B, the ash was stored separately, and only the lapilli fraction was returned to the drum. In experiment T3B, steel balls (220 g each) were added to simulate dense blocks.

The amount of ash produced analysed after each tumbling step was plotted as weight fraction of the starting load. To understand fine generation better, the ash was analysed by dry sieving at half-φ and laser diffraction analysis. For all three experiments, ash generation efficiency is negatively correlated with tumbling time, with T1 producing the smallest and T3B the highest amount of ash (as high as 47 wt.%). Noteworthy is the production of up to 18,20 wt.% of fine ash (<63 µm) and 2,83 wt.% of PM10 (≤10 μm) relative to the initial starting weight. These numbers are surprisingly high given the comparatively short and low-energy experiments. Accordingly, uninterrupted abrasion and comminution during PDC transport is a quasi-infinite source of ash supply, influencing PDC flow conditions and mobility and should be considered in future PDC runout and health impact models.

Reference: Figueiredo, C., Kueppers, U., Pereira, L. et al. Shape evolution of pumice during granular flow. Commun Earth Environ 6, 941 (2025). https://doi.org/10.1038/s43247-025-02936-4

How to cite: Kueppers, U., Bauer, S., Figueiredo, C., and Beyer, U.: Making dust: The easy way of generating (a lot of) fine ash during tumbling experiments, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14211, https://doi.org/10.5194/egusphere-egu26-14211, 2026.

Nearly 20 million people live within a100 km radius from Popocatepetl volcano in central. Mexico. Ashfall is frequent since emissions began in 1994. Ash is sampled weekly or daily depending on the activity. A 200 site ash monitoring network is enhanced by community participation and reports. Negative magnetic anomalies (WD 5nT) during March and April 2023, September 2024 and during the first 4 days in April 2025 were correlated with harmonic tremor and small chemical changes in the springwater near the volcano. These precursors preceded abundant ash emission in 2023 and 2024 by 2 month and small ash emissions in 2025 and 2026. This allowed us to advice Civil Protection weeks before and get the population prepared with facemasks and get school protocols into place. The Mexico City and Puebla international airports were closed for 2 days in 2023 and bad road visibility due to the fine ash caused serious transportation problems. Crops were also affected but only minor respiratory health problems occurred. Ash composition varied from 58- 60 SiO2 % in 2023 and from 59 -61 SiO2 % in 2024. Smaller amounts of ash in 2025 and 2026 are associated with the formation of small lava domes while the larger emissions result from a constant ash emission over several days.

How to cite: Martin Del Pozzo, A. L., González Hernández, S. K., Díaz Cruz, M. A., Sandoval García, M., and Cifuentes Nava, G.: Precursors to Tephra Emission, Variation and Dispersal at Popocatepetl Volcano (Mexico), 2023-2026 , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-15135, https://doi.org/10.5194/egusphere-egu26-15135, 2026.

Pyroclastic Density Currents (PDCs) are deadly, highly destructive, fast-moving, ground-hugging, mixtures of hot gas and volcanic particles. PDC high velocities, dynamic pressures, and temperatures make direct field measurements extremely challenging. Due to the combination of high-impact to the natural and built environment, and the difficulty of obtaining direct measurements, remote detection methods would be of benefit to their study and early warning systems. Acoustic methods have been proposed in the past for this application, however, due to sparse field data, there remains a limited understanding of the fundamental question regarding the source of the recorded acoustic signals. The Pyroclastic flow Eruption Large-scale Experiment (PELE) is a large-scale experimental facility designed to synthesize pyroclastic density currents (PDCs) within a laboratory environment. PELE has been augmented with acoustic sensors allowing for the direct observation of physical properties and the location of the experimental flow with time-synchronized acoustic data.This study examines the location and source of the acoustic signals that have been previously identified in field data.  Combining signal cross-correlation between sensors with known offsets within the experimental channel, and high speed imaging of the experimental flow, the resulting dataset showed that there are multiple pulses of signal sources within a single flow. These signals seem to be associated with the interface of the flow and the atmosphere. This result highlights that, while previously the source of the field signals was attributed to the front of the flow, there are multiple sources within the flow. Further research should be undertaken to further explore the role of these different sources and topography and path in the field. Additionally, this insight should be taken into account for sensor deployment design and early warning system development. 

How to cite: Perttu, A., Lube, G., Jellinek, M., Ichihara, M., Robert, J., and Brosch, E.: Insights into Acoustic Sources from Pyroclastic Density Currents , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16597, https://doi.org/10.5194/egusphere-egu26-16597, 2026.

Campi Flegrei caldera (CFc) is one of the most hazardous volcanic systems in Europe, with over 1.2 million people in Naples living within 10 km of the active volcano and the neighbouring volcanoes of Ischia, Procida, and Somma-Vesuvius^[1]. Constraining the explosive eruptive history of CFc is critical for understanding future volcanic hazards. Over the past 40 kyr, three caldera-forming eruptions have occurred at CFc: the Campanian Ignimbrite (CI; 40 ka^[2]), the Masseria del Monte Tuff (MdMT; 29.3 ka^[3]) and the Neapolitan Yellow Tuff (NYT; 14.9 ka^[4]). Whilst these major events are well characterised, smaller eruptions between them remain poorly constrained in magnitude and time despite representing key phases in the magmatic evolution of CFc. Few proximal sections preserve a detailed record of eruption deposits from the interval between the CI and NYT.

We present new detailed field and glass geochemical data from Monte di Procida, southwest of CFc, which records 21 tephra units, including the CI and NYT. This represents the most complete CI–NYT sequence identified to date. Three main CFc compositional subgroups are recognised: (i) a dominant NYT-like trachytic melt (~60 wt.% SiO₂) with limited variability, (ii) a more evolved trachytic subgroup (~64 wt.% SiO₂), and (iii) a trachybasaltic composition (~55 wt.% SiO₂). The section also contains distinct Solchiaro (~23 ka^[5]) tephras from Procida, separated by an Ischia-derived ash, evidencing contemporaneous activity during this interval across the Campanian Volcanic Zone. These data reveal that at least 15 of the eruption deposits are from CFc, indicating a higher pre-NYT eruptive tempo than previously recognised.

The Monte di Procida record reveals greater activity with 11 eruptions in the 9 kyr preceding the NYT eruption, suggesting frequent activity in the build-up to the NYT caldera-forming eruption. Inter-eruption glass compositions show similar chemical signatures with limited variability in major and trace elements, complicating the use of tephras from this record in wider regional correlations.

References:

1. Meredith et al. (2025) Nat. Hazards Earth Syst. Sci. 25: 2731-2749.

2. Giaccio et al. (2017) Sci. Rep. 7: 45940.

3. Albert et al. (2019) Geology. 47: 595-599.

4. Deino et al. (2004) JVGR. 133: 157-170.

5. Morabito et al. (2014) Glob. Plan. Change 123: 121-138.

How to cite: Kane, G., Natale, J., Isaia, R., Stock, M., Teixeira, L., Tomlinson, E. L., and Smith, V. C.: Insights into eruption activity between recent caldera-forming eruptions at Campi Flegrei caldera (southern Italy): A Detailed Tephrostratigraphic Record from Monte di Procida., EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17012, https://doi.org/10.5194/egusphere-egu26-17012, 2026.

Stromboli volcano, Italy, is characterized by persistent explosive activity occasionally punctuated by more energetic explosions, called paroxysms, during which deposit-derived pyroclastic density currents (PDCs) may be generated by the gravitational instability of hot, unstable pyroclastic deposits. Although typically confined within the Sciara del Fuoco, a prominent depression on the volcano’s NW flank, historical events such as the 1930 and 1944 paroxysms demonstrate that these flows can propagate beyond this depression, posing a significant hazard to inhabited areas and climbers.

This study combines the reconstruction of a well-documented historical event with a probabilistic hazard assessment to evaluate the potential impact of deposit-derived PDCs over the entire island. The September 11, 1930 paroxysm is reanalyzed by integrating new field observations, historical records, and numerical modeling, providing a test case for model calibration and a first probabilistic reconstruction of the phenomenon. Recent erosive floods exposed previously unrecognized PDC deposits in the San Bartolo valley, complementing those identified in the Vallonazzo basin. These new data, together with eyewitness accounts, were used to constrain maximum flow thicknesses along the valleys. A shallow-water dense granular flow model coupled with an inversion algorithm indicates that the PDC propagated mainly within these valleys, with limited secondary flows in adjacent basins. Consistently with field evidence, the Vallonazzo flow reached the sea, whereas the San Bartolo flow stopped near the local church, with an estimated total remobilized volume between 34,000 and 59,000 m³. Results also highlight the strong dependence of invaded areas on the location of the source material.

Building on this calibration, a new probabilistic framework based on random circular sector source models is applied to assess PDC hazard at the scale of the island. Six main drainage basins with significant hazard potential were identified. Among these, San Bartolo, Scalo dei Balordi, and Ginostra “A” show the highest conditional invasion probabilities, while other inhabited valleys exhibit lower but still non-negligible values. By coupling spatial invasion probabilities with a temporal occurrence model linking paroxysm frequency to PDC generation, we estimate a substantial probability of future PDC invasion outside the Sciara del Fuoco over decadal to multi-decadal timescales, despite the large uncertainties associated with the limited historical record.

How to cite: Neri, A., Bevilacqua, A., Geddo, Z., Corna, L., Di Roberto, A., Di Traglia, F., Pompilio, M., Bertagnini, A., de'Michieli Vitturi, M., Flandoli, F., and Tadini, A.: Deposit-derived pyroclastic density currents at Stromboli: from the 1930 event reconstruction to probabilistic hazard assessment, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17226, https://doi.org/10.5194/egusphere-egu26-17226, 2026.