Studies may be focused at the regional scale, investigating the tectonic setting responsible for and controlling volcanic activity, both along divergent and convergent plate boundaries, as well in intraplate settings. At a more local scale, all types of surface deformation in volcanic areas are of interest, such as elastic inflation and deflation, or anelastic processes, including caldera and flank collapses. Deeper, sub-volcanic deformation studies, concerning the emplacement of intrusions, as sills, dikes and laccoliths, are most welcome. We also particularly welcome geophysical data aimed at understanding magmatic processes during volcano unrest. These include geodetic studies obtained mainly through GPS and InSAR, as well as at their modelling to imagine sources.
The session includes, but is not restricted to, the following topics:
• volcanism and regional tectonics;
• formation of magma chambers, laccoliths, and other intrusions;
• dyke and sill propagation, emplacement, and arrest;
• earthquakes and eruptions;
• caldera collapse, resurgence, and unrest;
• flank collapse;
• volcano deformation monitoring;
• volcano deformation and hazard mitigation;
• volcano unrest;
• mechanical properties of rocks in volcanic areas.
The Svartsengi volcanic system, SW-Iceland, started to show unrest in early 2020 with a series of inflation-deflation cycles. In late October 2023, it started to inflate at unprecedented rate of ~8 mm/day until it produced a ~15 km long dike intrusion on the 10 November 2023. The inflation resumed soon after and has been continuous since, only interrupted by deflation periods concurrent to additional dike injections and associated eruptions at the Sundhnúkur crater row. Geodetic modelling, assuming a deformation source within a uniform elastic half-space, infers pressure changes between about 3-6 km depth, with inflow causing volume increase rates of 3-8 m3/s of a crustal volume inferred to be a magma domain (complex of liquid magma, crystal mush and hot rock). Displacements mapped by GNSS (Global Navigation Satellite System) geodesy are used to derive volume change estimates of the magma domain in near real-time. Additional geodetic inversions also use extensive interferometric analysis of synthetic aperture (InSAR) satellite images. These results have been used to map the locations and volumes of the intruded dikes and the concurrent contraction volume of the magma domain. Since 27 October 2023, we infer continuous inflow of magma from depth into the magma domain, which appears to continue even during outflow into dikes and the extrusion of lava flows. We analyze all the inflation-deflation cycles, to better understand the mechanisms controlling the activity. The relationship between volume loss of the magma domain during these events and subsequent volume recharged to the domain (before the next event is triggered) has allowed success in forecasting diking/eruption onset in the medium and short term.
How to cite: Drouin, V., Parks, M., Sigmundsson, F., Hjartardóttir, Á. R., Geirsson, H., Birkefeldt Moller Pedersen, G., Munoz Cobo Belart, J., Barsotti, S., Lanzi, C., Vogfjorð, K., Hooper, A., Ófeigsson, B. G., Hreinsdóttir, S., Gestsson, E. B., Þrastarson, R. H., Einarsson, P., Tolpekin, V., Rotheram-Clarke, D., Gunnarson, S., and Óskarsson, B. and the other co-authors: Repeated inflations, deflations, dike injections and eruptions since 2023 in the Svartsengi volcanic system, Reykjanes Peninsula, Iceland, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17523, https://doi.org/10.5194/egusphere-egu25-17523, 2025.
Following an increase in seismic activity in December 2019, a pressure increase began in the center of the Svartsengi volcanic system in January 2020, as inferred from geodetic observations. The first diking event occurred, however, in the nearby Fagradalsfjall volcanic system, about 10 km east of Svartsengi, 24 February – 19 March 2021, when an ~9 km long dike gradually formed with geodetically inferred initial volume increase rates up to 35 m3/s, during the first week of diking. The total dike volume was ~34 Mm3, based on joint inversions of InSAR and GNSS observations that have been extensively used to study this and later events in the area. This dike intrusion culminated in an eruption on 19 March 2021. The initial dike had minor incremental volume increase in association with opening of additional vents above the dike during the 6-month-long 2021 eruption, with near-surface opening in the top few hundred meters. Three additional dike intrusions occurred in the Fagradalsfjall area between December 2021 to July 2023, with initial magma flow rates between 22 to 70 m3/s. The Fagradalsfjall dikes were fed through a channel with an inferred cross-sectional area of about ~2-4 m2, passing through the lower crust from a source near the crust-mantle boundary, with a geodetically imaged deflation source at about ~12-13 km depth. Since late 2023, activity has been focused at the Svartsengi system, with 9 diking events and 7 eruptions in 2023-24. Initial diking there occurred on 10-11 November 2023 with inferred peak flow rates of ~7400 m3/s when an ~15 km long dike formed, following magma accumulation near the brittle-ductile boundary at about 4-5 km depth. The inferred cross-sectional area of the limiting part of the channel from the Svartsengi magma domain feeding the zone where dikes have formed in 2023-24 is on the order of ~2000 m2 or about 2-3 orders of magnitude larger than that inferred at Fagradalsfjall. This and the different depth of magma storage in the plumbing systems at Fagradalsfjall and Svartsengi explains their different behaviour in recent years, that are coupled in such a manner that only one of of the systems has been primarily magmatically active at each time since 2020.
How to cite: Sigmundsson, F., Parks, M., Drouin, V., Geirsson, H., Vogfjörð, K. S., Lanzi, C., Ófeigsson, B., Hreinsdóttir, S., Hooper, A., Yang, Y., Greiner, S. H. M., Hjartardóttir, Á. R., and Einarsson, P.: Volcano-tectonic activity on the Reykjanes Peninsula, Iceland, since December 2019: 13 dike injections in the Svartsengi and Fagradalsfjall volcanic systems reveal a wide range of magma flow rates into dikes , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13047, https://doi.org/10.5194/egusphere-egu25-13047, 2025.
Only a few large dykes have been intruded during the era of modern satellite geodesy and as a result the dynamics of how dikes grow over many tens of km’s and interact with faults is poorly understood. Here we exploit the exceptional spatial and temporal resolution of InSAR during the December 2024-January 2025 Fentale dyke (Ethiopia) combined with seismicity and numerical models to study the dynamics of a large dyke intrusion. Our results show that a ~40 km long dyke fractured the entire Fentale-Dofen volcanic segment of the Ethiopian Rift from 19 December 2024 to 03 January 2025. The dyke first migrated laterally in just ~15 days but opening continued for a protracted period. Throughout the episode, melt was fed from a single reservoir beneath Fentale at the southern end of the segment. The dyke migration ended with the triggering of two earthquakes, a Mw 5.5 and 5.7 on the 3 and 4 of January, ~20 km beyond the dyke tip. Dyke opening and concomitant deflation at Fentale instead continued until the time of writing this abstract. The volume and seismic character of the Fentale dyke are comparable to other major rifting episodes observed at mature rifts and ridges, like the 2005 Dabbahu dyke, the 2014 Bardabunga dyke, and the ongoing Reykjanes episode. Our results support models of repeated magmatic rifting episodes being the main mode of plate boundary extension even in youthful continental rifts. Our observations are also in agreement with theoretical dyke propagation models in which faulting ahead of the dyke arrests its propagation.
How to cite: Pagli, C., La Rosa, A., Cesca, S., Rivalta, E., Wang, H., Bonano, M., Striano, P., Keir, D., Ayele, A., and Lewi, E.: Dynamics of a large dyke intrusion at Fentale in the Ethiopian rift, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5190, https://doi.org/10.5194/egusphere-egu25-5190, 2025.
Underground magmatic activity is often detected by analyzing geophysical signals recorder at the Earth's surface such as seismicity, ground deformation, gravitational and magnetic anomalies. Inversion of these signals can provide information on the source characteristics. On the other hand, forward modeling can aid in prediciting expected signals as a onsequence of specific source, and path, properties.
In this work, we employ a finite element model of magma dynamics and coupled rock mechanics to retrieve ground deformation and gravitational anomalies expected as a consequence of magma arrival from depth into shallower reservoirs. The sensitivity of ground deformation and gravitational anomalies to different magma dynamics patterns is investigated with a parametric study on the effects of buoyancy and overpressurization within the magmatic system. The resulting space-time distribution of ground displacement and gravity anomaly shows that interpretation of observed patterns is not straightforward as soon as the assumption of simple (pressurized ellipsoid, dike) magmatic source is abandoned. The results of this study suggest cautious interpretations of observed deformation and gravity patterns, in particular in relation to the complexities introduced by the spectrum of forces driving magmatic movements, and the multifaceted magma dynamics across multiple interconnected reservoirs. Similar care is suggested when inverting monitoring signals, especially when combining multiple signals such as those associated with ground deformation and gravity changes, that albeit originating from the same overall dynamics might reflect, under some circumstances, different processes occurring in separate regions of the magmatic domain.
How to cite: Montagna, C. P., Longo, A., Garg, D., and Papale, P.: Sensitivity of ground deformation and gravity anomalies in the detection of complex underground magmatic sources, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17303, https://doi.org/10.5194/egusphere-egu25-17303, 2025.
Between 2004 and 2005, an increased seismic activity exceeding background levels was recorded in Tenerife, the most populated island of the Canary Archipelago. Some earthquakes were felt on the island, causing concern about a possible eruption among the island's population. Ground deformation analysis, conducted using Envisat satellite data from 2003 to 2010 and the Independent Component Analysis (ICA) statistical tool, revealed several centimetres of deformation within the Teide-Pico Viejo volcanic complex. This deformation was modelled and attributed to an ellipsoidal source beneath the Teide-Pico Viejo volcanoes, likely associated with hydrothermal activity.
Since 2016, the island's primary volcanic complex, the Teide-Pico Viejo stratovolcano, has exhibited increased seismicity and heightened volcanic manifestations. Between 2023 and 2024, the same volcanic area, the Teide-Pico Viejo complex, experienced renewed ground deformation in a region similar to that affected during the 2004-2005 unrest. To investigate the anomalies observed in the Teide-Pico Viejo stratovolcano and compare its current behaviour to that of 2004-2005, a DInSAR SBAS time-series analysis was performed using data from the Sentinel-1 sensor. Ascending and descending orbits were selected, analysing data from January to December 2024. The quality of the SBAS dataset was enhanced through detailed ICA decomposition, removing signal components unrelated to volcanic ground deformation. The component representing a distinct ground deformation pattern was then modelled to identify the location and geometry of the deformation source.
The SBAS DInSAR data from the Sentinel-1 sensor indicated that ground deformation was concentrated in the stratovolcano area, with displacement values approximating 3 cm/year. ICA decomposition identified the deformation pattern responsible for the observed ground displacement in the Teide-Pico Viejo volcanic complex. Modelling this ICA-derived pattern is crucial for understanding the source of the observed behaviour and determining whether its origin is magmatic or hydrothermal.
How to cite: Przeor, M., D'Auria, L., Pepe, S., Tizzani, P., Pérez, N., and Castaldo, R.: Ground Deformation Trends in Tenerife (Canary Islands) Uncovered Through Time-Series Analysis of DInSAR SBAS and ICA Applied to the 2004-2005 and 2023-2024 Datasets, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18293, https://doi.org/10.5194/egusphere-egu25-18293, 2025.
Volcano geodesy plays a vital role in monitoring volcanic activity, yet the high instrument costs may restrict the establishment of ground-based monitoring networks. This is especially challenging in developing countries, where volcanic hazards can be significant. The use of cost-effective equipment can help mitigate this.
We present the design and positioning results of four cost-effective Global Navigation Satellite System (GNSS) units on Saba, Caribbean Netherlands. Each unit costs less than €1,000 and is equipped with solar charging capabilities, data logging, and data transmission via a 4G extension. The units operate independently and log high quality GNSS data, despite the harsh environmental conditions. We show that the positioning accuracy of these units is comparable to those of conventional permanent GNSS stations on the island, with standard deviations of 2-4 mm horizontally and about 6-9 mm vertically.
This makes them a viable option for expanding existing GNSS monitoring networks or establishing new networks in budget-constrained environments. The rapid deployment capability of these units also makes them suitable for use in hazardous applications where fast installations are essential. The schematics, material lists, and software for these units are made available to the community to encourage wider usage as well as further development and adaptation.
The results are published and further detailed information can be found in the paper by Krietemeyer and van Dalfsen (2025):
Krietemeyer, A., van Dalfsen, E., 2025. Cost-effective GNSS as a tool for monitoring volcanic deformation: A case study on Saba in the Lesser Antilles. Journal of Volcanology and Geothermal Research 459, 108263. doi:https://doi.org/10.1016/j.jvolgeores.2024.108263.
How to cite: Krietemeyer, A. and van Dalfsen, E.: Volcanic deformation monitoring using cost-effective GNSS: A case study on Saba, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6972, https://doi.org/10.5194/egusphere-egu25-6972, 2025.
We unambiguously document unrest at Taftan volcano. Summit uplift was detected using InSAR time series and its timing tightly constrained applying a new common mode filtering method. Uplift started and ended gradually lasting 10 months (July 2023 to May 2024). Uplift peaked at 11 cm/year rates, and during slowing-down several gas emission events occurred. Unrest was triggerless, uncorrelated with rainfall or seismic events. We favor internal driving processes with two possible scenarios: (1) dynamic hydrothermal alteration leading to permeability changes, shallow gas storage and pressurization, followed by opening of degassing pathways; or (2) a minor, undetected deep magmatic intrusion causing volatile exsolution and pore pressure increases within the hydrothermal system. Lack of post-unrest subsidence suggests persistence of hydrothermal high-pressure conditions at the summit and associated hazards. Our study shows how satellite imagery reveals hidden volcanic hazards at Taftan, and the need to implement a holistic volcano risk reduction strategy.
How to cite: Mohammadnia, M., Yip, M. W., Webb, A. A. G., and González, P. J.: Spontaneous transient summit uplift at Taftan volcano (Makran subduction arc) imaged using an InSAR common-mode filtering method, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7970, https://doi.org/10.5194/egusphere-egu25-7970, 2025.
How to cite: Jacques, E., Hoste-Colomer, R., Feuillet, N., Lemoine, A., van der Woerd, J., Crawford, W. C., Berthod, C., and Bachèlery, P.: Ring faulting and piston collapse in the mantle sustained the largest submarine eruption ever documented, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7134, https://doi.org/10.5194/egusphere-egu25-7134, 2025.
The stability, collapse dynamics and/or eruption style of a lava dome is mainly controlled by the rheological response of its constituent magmas to a range of internal and external stresses of various magnitudes and rates. Laboratory experiments carried out on natural lava-dome samples with high crystallinity (>50%) have provided empirical relations between the viscosity of the samples and the applied temperature and strain rate. These experiments have also provided valuable insight into the complex link between the samples’ elastic parameters and physical properties, including porosity and microcrack density (damage). In order to incorporate this information into large-scale numerical models for lava dome deformations, it is crucial to quantify how different deformation mechanisms alter the elastic parameters and viscosity of dome magmas. We address this problem by applying a thermodynamically-based visco-poroelastic damage model to the deformation data from high-temperature uniaxial experiments involving lava samples from Colima volcano (Mexico). The experiments involve constant stresses (2.8-28 MPa) and constant temperatures (935-947°C) representing realistic lava dome conditions. For each experiment, we invert the deformation data using a nonlinear optimization scheme to constrain the optimal model parameters. Using the optimal parameters, we estimate the amount of damage, porosity and irreversible (inelastic) strain as a function of time throughout the experiments.
Our damage model establishes a quantitative link between the elastic parameters and the porosity and microcrack density of the magmas. We find that the rheological behavior of all three samples throughout the experiments is “semi-brittle” (brittle-ductile), and that the samples deform dominantly by pressure-driven compaction and cataclastic flow. We also find that the effective viscosity of the samples is a combination of two components: a ductile component with a constant viscosity, and a damage-induced viscosity, which depends on the strain-rate and the rate of damage increase; the damage-induced viscosity is responsible for the nonlinear variations of the apparent viscosity of the samples. The elastic parameters in all three models are determined by the competition between degradation (damage increase) and inelastic compaction (porosity decrease). Moreover, across the three models, the inferred kinetic parameters (e.g., damage rate, yield-cap parameters) decrease approximately linearly with the applied stress. Finally, the cumulative counts of the Acoustic Emissions (AEs), which were recorded for two of the experiments, match the evolution of the damage in the models. We discuss the implications of our damage model and the further theoretical, numerical and experimental work required for establishing large-scale numerical models for lava dome deformations.
How to cite: Nikkhoo, M. and Lyakhovsky, V.: A damage model for semi-brittle deformation of dome magmas from Colima volcano, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17441, https://doi.org/10.5194/egusphere-egu25-17441, 2025.
The densely populated area of Naples, Italy, situated between the Campi Flegrei caldera and the Vesuvio volcano, is recognised as one of the most hazardous regions on the planet. Over the past 15,000 years, numerous eruptions have occurred at Campi Flegrei, accompanied by the resurgence of the centre of the caldera. Following a period of quiescence spanning 3,000 years and several centuries of subsidence, Campi Flegrei experienced another eruption in 1538, preceded by an increase in seismic activity and uplift. Since the 1950s, Campi Flegrei has experienced intermittent unrest, with four main episodes occurring between 1950–1952, 1969–1972, 1982–1984, and 2005 to the present. The unrest between 1982 and 1984 was followed by prolonged subsidence, and there has been an almost continuous uplift since the early 2000s. Somma-Vesuvio is a stratovolcano with a summit caldera (Mount Somma) and a recent cone (Mount Vesuvio) resulting from several Plinian eruptions. The most recent Plinian eruption of Vesuvio occurred in 79 AD, with sub-Plinian eruptions following in 472 and 1631, subsequently succeeded by semi-persistent activity that endured until 1944.The eruptive histories of Campi Flegrei and Vesuvio are different, and past erupted products show dissimilar characteristics. However, the compatibility of past erupted products with the possible existence of a single magma accumulation layer at a depth of 8–10 km is noteworthy, with geophysical investigations also suggesting the presence of this layer.
Recent studies have utilised ERS/ENVISAT (1993–2010) and Sentinel1 (2015–present) SAR data to demonstrate that ground deformation is partially attributable to sources at a depth of approximately 8 km during the Campi Flegrei uplift. Furthermore, the findings indicate that a depressurisation occurred at depth beneath Vesuvio in the early 2000s, and that there were possible deep interactions between the two volcanoes during the transition period between subsidence and uplift at Campi Flegrei.
From 2010 to 2015, the available COSMO-SkyMed images acquired in ascending orbit did not cover the western end of the Campi Flegrei, and the descending orbit images did not cover the area around Vesuvio. However, the ESA's PP0094512 project, entitled "Campi Flegrei caldera evolution in between ERS/ENVISAT and Sentinel1 missions", has enabled the generation of deformation time series from Radarsat2 images encompassing the entire volcanic area. This achievement was made possible by the development of a hybrid procedure; this procedure consists of using various free or open-source software in sequence — SNAP (https://step.esa.int/main/download/snap-download/), GMT (https://www.generic-mapping-tools.org/), gdal (https://gdal.org/), GMTSAR (https://topex.ucsd.edu/gmtsar/) — with appropriate adaptations. The validity of the series is confirmed through comparison with GNSS (Global Navigation Satellite System) data from the INGV NeVoCGPS network.
The first results obtained by combining the ERS/ENVISAT, Radarsat2 and Sentinel1 data, and in particular the evolution of non-moving statistically independent deformation sources, are presented.
How to cite: Amoruso, A., Crescentini, L., and Salicone, G.: ERS/ENVISAT, Radarsat2 and Sentinel1 SAR images: ground deformation at Campi Flegrei and Vesuvio, Italy, since 1993, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15526, https://doi.org/10.5194/egusphere-egu25-15526, 2025.
Campi Flegrei, the largest active caldera in Europe and home to over 350,000 people, has exhibited accelerating ground inflation and intensified seismic activity since 2005. Using monitoring data collected from 2000 to November 2023, we quantified the decadal accelerating trends, characterized oscillations of varying frequencies, and explored the relationships between deformation and seismic activity.
Analysis revealed a strong temporal correlation between deformation rates and seismic activity, expressed by an exponential relationship between ground deformation and the cumulative number of earthquakes. Since around 2010, the relationship between the cumulative number of earthquakes and vertical uplift has been better described by two exponential functions with increasing exponents over time, with the inflection in the period between 4/2020 and 9/2022.
This inflection effectively represents the rising intensity of seismic activity since about 2020 and is interpreted as a stress memory effect, attributed to reaching a stress level in the shallow crust comparable to the peak stress during the 1982–84 crisis. The recent exponential trend differs from the previously suggested linear relationship between these two variables and is interpreted as indicative of a progressive evolution in the quasi-elastic behavior of the shallow crust of Campi Flegrei caldera. Furthermore, this exponential-type relationship differs from the linear-type relationship observed during the 1982–84 crisis, suggesting that the two crises are driven by different forcing sources or mechanisms.
Crucially, these findings provide evidence of an accelerating sensitivity of seismic activity to caldera inflation. During 2024, the exponential correlation between vertical uplift and the cumulative number of earthquakes remained consistent. The Md 4.4 event on May 20, 2024, aligns closely with the hypothesized patterns, highlighting concerns about the possibility of new seismic crises should the bradyseism persist with these trends and relationships.
How to cite: Bevilacqua, A., Neri, A., Di Martino, P., Giudicepietro, F., Macedonio, G., and Ricciolino, P.: Quantifying the link between ground deformation and seismicity during the ongoing unrest of Campi Flegrei caldera (Italy), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20383, https://doi.org/10.5194/egusphere-egu25-20383, 2025.
Calderas often host monogenetic volcanism during their post-collapse evolution, and this is usually coupled with ground deformation episodes that lead to a resurgence in the long term. Understanding the non-trivial relationships between erupted volumes and resurgence deformation is critical to properly facing volcanic unrest at densely populated volcanoes. This sense of urgency is strongly felt for the restless Campi Flegrei caldera (southern Italy), which is experiencing elevated volcanic unrest with heightened levels of seismicity, geochemical anomalies and, not least, ground uplift. In this work, we reassess the state-of-the-art understanding of ground uplift at Campi Flegrei, addressing the affirmed models and interpretations of the observables at different time scales. As an element of novelty in the literature, we provide a quantitative estimation of the deformation shape and amount of ground uplift and subsidence, constraining the mode of resurgence and individuating deformation anomalies. This allowed us to comprehensively reconstruct the history of deformation throughout the Holocene. We also constrain the timing of volcano-tectonic fault activity and the reactivation of caldera structures that accommodate the deformation. On these grounds, in combination with the reassessment of spatial and temporal patterns of volcanism, we provide a robust interpretative model explaining the relationship between ground deformation and eruptions, including its significance in terms of volcanic hazards. Our results challenge the existing models linking ground deformation and eruptions and should foster constructive discussion about the volcano deformation dynamics at Campi Flegrei.
How to cite: Natale, J. and Vitale, S.: Uncovering the long-term evolution and pattern of ground deformation in active calderas: reconciling Holocene volcano-tectonic processes and volcanism at Campi Flegrei (southern Italy), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7238, https://doi.org/10.5194/egusphere-egu25-7238, 2025.
The gravitational instability of glowing volcaniclastics can lead to the formation of deposit-derived pyroclastic density currents (PDCs). These flows can mobilise volumes of 10³ to 10⁷ m³, travelling several kilometres from their source while maintaining extremely high temperatures, posing a significant risk to nearby communities and visitors. Deposit-derived PDCs are typically formed by two primary mechanisms: (i) those driven by magma thrust, resulting in the collapse of crater rims, and (ii) those triggered by the collapse of hot material on volcanic slopes due to factors such as exceeding the angle of friction, undercutting or overloading by fresh volcaniclastics or lava flows. At Vesuvius, Italy, deposit-derived PDCs were directly observed during the 1822 and 1944 eruptions, both characterized by activity that varied from effusive, fire fountaining, sub-Plinian, to late Vulcanian. During the 1944 eruption, which occurred between 18 and 29 March, deposit-derived PDCs were generated during the fire fountaining phase (Phase 2) following the lava emission phase (Phase 1). This study presents a comprehensive investigation of the formation mechanisms of deposit-derived PDCs during the 1944 eruption. It integrates historical documentation and photographs by Giuseppe Imbò, the Director of the Vesuvius Observatory at the time, with fieldwork aimed at evaluating the geometric relationships between the proximal accumulation, welding and detachment zones. The spatial distribution of PDC deposits around the volcanic cone was mapped using photogrammetry-based digital elevation models (DEMs) and 1943 orthophotos. Volume estimates for deposits in the proximal cone and surrounding areas were derived by comparing the 1943 DEM with a more recent 2012 DEM. This analysis provided new insights into the dynamics of PDC formation and its spatial and volumetric characteristics. The results of this study show that the failure of glowing volcaniclastic deposits and the subsequent generation of deposit-derived PDCs is controlled by both the pre-eruption morphology of the volcano and the distribution of deposits with different degrees of welding. In particular, deposits accumulated near the old crater rim with lower degrees of welding were more susceptible to collapse, whereas zones with higher welding degree were less likely to fail. Conversely, in areas further from the crater rim where material from fire fountains accumulated, a greater thickness of deposits was required to initiate failure. These variations significantly influence the timing and volume of individual PDCs. In proximal areas, smaller flows were generated more quickly, while in distal areas, larger flows developed later, particularly towards the end of the fire fountaining phase. These results provide critical insights into the mechanisms governing the formation of deposit-derived PDCs in volcanoes with comparable eruptive styles. Such volcanoes can produce deposit-derived PDCs that extend over areas considerably larger than those directly affected by the primary eruptive phenomena.
How to cite: Di Traglia, F., Natale, J., Falasconi, A., Bevilacqua, A., Buono, G., Calandra, S., Favalli, M., Fornaciai, A., Frontoni, A., Grillo, T. O., Intrieri, E., Pappalardo, L., Nave, R., Romano, C., Santo, A., and Vona, A.: Deposit-Derived Pyroclastic Density Currents from the 1944 Eruption of Mount Vesuvius, Italy: Integrating Field Observations, Historical Accounts, and Morphological Data to Reconstruct Predisposing Factors and Triggering Mechanisms, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2267, https://doi.org/10.5194/egusphere-egu25-2267, 2025.
Mount Etna, located in the central Mediterranean on the north-eastern coast of Sicily (Italy) is one of the most active and hazardous strato-volcanoes in the world whose south-eastern flank is sliding towards the Ionian Sea. Flank collapses can be caused by gravitational spreading and tectonic forces, leading to crustal fracturing and possible opening of magma pathways. To investigate their effect on the sliding flank at Etna, we created a 3D geodynamic model of the volcano, containing the primary geological parameters and produced ground deformation with the 3D thermomechanical finite differences code LaMEM (Lithosphere and Mantle Evolution Model). To achieve a sufficient model resolution, simulations were run in parallel on an Open Computing Cluster for Advanced data Manipulation (OCCAM). The geometry of the model was built with the GeophysicalModelGenerator.jl package, also including real topography through the GMT.jl package by using the Julia programming language. Implemented geometries, which are based on geological maps and interpretation of seismic velocity data, were assigned rock parameters from laboratory-scale values and computational simplicity.
The model includes most importantly an upper brittle crust with a south-eastern flank that is decoupled by surrounding objects of weak rock characteristics relative to the flank, represented by two bounding fault systems (Pernicana in the north and Mascalucia-Tremestieri, Fiandaca-Pennisi and Gravina in the south) and an underlying Apennine-Maghrebian Chain. Additionally, the effect of a visco-elastic basement, a solidified high velocity intrusive body (HVB) and a supercritical fluid volume (LVZ) with strong and weak rock parameter values, respectively, were tested. 4 types of low-velocity zones (LVZ) and 2 types of high-velocity bodies (HVB) were implemented, with geometries deriving from seismic imaging.
We observed the impact of each implemented geometry and its sensitivity to parameters by comparing the model results to GPS observations quantitatively, estimating the misfit between the model and data using the coefficient of determination. To quantitatively compare the geodynamic model results, deformation data from time periods (2004-2006), covering inflation and deflation phases of low intensity (Bonforte et al. 2008), were used to isolate the sliding of Etna’s southeastern flank through gravitational spreading. The greatest effect could be observed when adding the visco-elastic basement to the brittle upper part of the model, which also increased the fit to GPS observations. HVB presence seems to not have a significant effect on geodynamic model, but contributes to its stabilization, while a sphere shape geometry is the best choice for fitting the LVZ
How to cite: Vinciguerra, S., Bensing, M., De Siena, L., and Puglisi, G.: Seismic response to volcanic processes at Mount Etna: coupling thermomechanical simulations with seismic wave-equation modelling, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5982, https://doi.org/10.5194/egusphere-egu25-5982, 2025.
Volcán Uturuncu is a volcano located in the southwestern corner of Bolivia, near the borders with Chile and Argentina. It sits above the Andean subduction zone and is part of the Altiplano-Puna Volcanic Complex (APVC). Volcán Uturuncu is situated on top of the Altiplano-Puna Magma Body (APMB), which is currently the world's largest continental silicic partial melt reservoir. This reservoir is estimated to hold a total volume of 500,000 km3 of 20-30% partial melt and is located about 15 to 20 kilometers below sea level.
Volcán Uturuncu has not produced any eruption during the last 250,000 years, effectively making it an "extinct" volcano. However, the presence of active fumarole fields and the discovery of a consistent uplift pattern suggest that this volcano remains, up until this day, a dynamic system. Hence, numerous geophysical and geochemical surveys have been conducted during the past decades to understand the physical processes behind the recent unrest of this "zombie" volcano. Thay also aimed to shed light on the dynamics between the APMB and the near-surface volcanic-hydrothermal activity. Recent seismological studies worked on constraining the crustal stress distribution, by mapping the faults below Volcán Uturuncu and studying the seismic anisotropy distribution in the surrounding area. Findings from these studies reveal a complex network of fractures with a strong NW-SE-directed seismic attenuation and anisotropy, seeming to indicate the preferential pathway of fluids (Hudson et al. [2022, 2023]).
With this new information in mind, we aim to re-assess the previous electrical resistivity model of Volcán Uturuncu, which was obtained from isotropic inversion of magnetotellurics (MT) data by Comeau et al. [2016]. This model shows a pattern of low resistivity and high resistivity structures, which was interpreted as a series of magmatic dykes. However, this interpretation may overlook the inherent anisotropy of the system. Thus, we aim to generate electrical resistivity models allowing for isotropic and anisotropic zones and assess the results in the context of the newly available scientific data. We will also present preliminary results from the joint inversion of MT and gravity data. Such joint modeling allows us to delineate the density signature of the resistivity anomalies in the subsurface. This can help us in determining whether low resistivity structures represent either saline brines, partial melt or dense sulfide mineralization.
References:
Comeau et al. [2016] - New constraints on the magma distribution and composition beneath volcán uturuncu and the southern bolivian altiplano from magnetotelluric data. https://doi.org/10.1130/GES01277.1
Hudson et al. [2022] - From slab to surface: Earthquake evidence for fluid migration at Uturuncu volcano, Bolivia. https://doi.org/10.1016/j.epsl.2021.117268
Hudson et al. [2023] - Hydrothermal Fluids and Where to Find Them: Using Seismic Attenuation and Anisotropy to Map Fluids Beneath Uturuncu Volcano, Bolivia https://doi.org/10.1029/2022GL100974
How to cite: Manara, F. and Comeau, M.: New Insights on the Volcanic-Hydrothermal System beneath Volcán Uturuncu (Bolivia) - Modeling the Electric Anisotropy and Jointly Inverting Magnetotellurics & Gravity Data, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-352, https://doi.org/10.5194/egusphere-egu25-352, 2025.
Fluid convection in many hydrothermal systems is driven by heat and energy provided by cooling igneous intrusions, while flow pathways are affected by rock permeability. Increased permeability in fracture zones and faults can form preferred fluid flow pathways. Although field evidence indicates that flow localisation in fracture zones and faults is a common phenomenon, its quantitative impact on heat and mass transfer around cooling intrusions has remained understudied. Here, we present three-dimensional numerical fluid flow simulations of a conceptual caldera setting with a ring fault to (1) explore the spatio-temporal evolution of heat and mass transfer, (2) quantify the effects of a high-permeability ring fault on fluid transport, and (3) describe the intra-fault flow dynamics. A circular, cooling magma chamber emplaced at 3 km depth acts as active heat source and an inwardly-dipping, cone-shaped zone of increased permeability represents the bounding caldera ring fault. We systematically vary the permeability of the bulk rock, the ring fault, and the crystallised intrusion, as well as the temperature (TBDT) at which rocks start to deform ductile and become impermeable to explore their first-order controls on heat and mass transfer in a caldera setting.
We observe two distinct intra-fault flow scenarios: (1) intra-fault convection allows for increased meteoric recharge and occurs when the fault permeability is at least two orders of magnitude larger than the permeability of the surrounding rock; and (2) upflow along the fault plane occurs via a continuous upflow front in case of permeability contrasts lower than two orders of magnitude. Both scenarios lead to a fault-focused fluid transport during the first ~5 kyrs, where hot fluids are directly fed into the fault plane by the underlying heat source, forming near-surface boiling zones. ~20–30 % of the total energy transfer to shallower depths <1.5 km takes place during this early flow stage and is accommodated by the ring fault. A continually cooling magma chamber and the consequently shrinking heat source shifts upflow of hot fluids towards the caldera infill. This shift of localised fluid upflow leads to the formation of a hydrothermal plume, which accounts for ~60–70 % of the total energy transfer to depths <1.5 km during the first 20–30 kyrs.
The efficiency of heat mining and how fast energy is transferred towards the surface is affected by the TBDT and by the permeability of the crystallised magma chamber. A higher TBDT allows fluids to migrate through hotter areas and increased permeability (e.g., caused by cooling joints) enables fluids to infiltrate into the crystallised magma chamber and therefore to harness energy more efficiently.
Overall, we conclude that ring faults can be important structures in caldera settings that transiently localise increased mass and heat transfer over a hundreds of years period, however, they may become less significant on geological timescales, particularly when the location of the heat source changes, which may reduce the input of hot fluids into the fault plane.
How to cite: Köpping, J. and Driesner, T.: Transient heat and mass transfer in a caldera setting quantified by 3D numerical simulations, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10738, https://doi.org/10.5194/egusphere-egu25-10738, 2025.
The Carlsberg ridge (CR) is a slow spreading mid-ocean ridge (MOR), which separates the Indian and Somalian tectonic plates in the northwest Indian Ocean. The CR has a total length of 1500 km with only four sites having hydrothermal activities being identified. Hydrothermal activities associated with the MORs can leave its signatures into the sediments. Eight sediment spade cores (SCs) from the ridge valley and flank regions of CR have been analysed for rock magnetic and geochemistry to find/fingerprint the presence of hydrothermal activity. Magnetic susceptibility (clf) ranges between 1.3 and 37.1 x10-8 m3 with relatively higher values in the ridge valley sediment cores. High clf and coarser magnetic grainsize observed in area A and two cores from area B can be probable new sites with active/ extinct hydrothermal activity in the vicinity . S – ratio and X-ray Diffraction (XRD) confirms the presence of magnetite as the main magnetic mineral in the sediment. Calcium carbonate (CaCO3) ranges from (42.8–89.6%) and organic carbon (Corg) varies between 0.3% and 2.9% in all the spade cores analysed. High concentration of CaCO3 is present in ridge flank sediment may be related to high surface water column productivity. The sediment core 77/4 records clear enrichment of chalcophile elements Cu, Cd, Pb, Co, Zn, which may be due to rapid loss from the neutrally buoyant plume either by preferential settling, as such the above elements concentration is relatable with the concentration of another core 77/6 from area B except Cu and Cd. The low concentration of Cu and Cd may be linked to the oxidative dissolution of sulphides. Downcore similarity in variations in two sediment cores from the valley and flank, confirms common processes controls their variations, that may be present under the plume trajectory. The rare earth element (REE) concentration for all the cores varies from 84.1 ppm to 206.6 ppm with middle rare earth element (MREE) enrichment, and highest concentration of REEs for the flank core. Magnetics, trace elements and REE suggest hydrothermal activity in the study area.
How to cite: Lenka, S., Kessarkar, P. M., Fernandes, L. L., and Gomes, C.: Hydrothermal signatures along the Carlsberg ridge using magnetic and geochemical investigations, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10962, https://doi.org/10.5194/egusphere-egu25-10962, 2025.
Fourier Transform Infrared Spectroscopy (FTIR) analysis represents an advanced method for the study of mineralogical neogenesis in volcanic environments [1]. It provides information on several elemental bonds (such as O-H, Si-O-Si, C-O, N-H, B-O) useful to detail mineral associations and organic molecules, and to unravel the inorganic-to-organic matrices interaction with implications on biotechnological applications and life evolution [2].
This study concerns with the application of the FTIR methodology to the areas of Campi Flegrei and Vulcano Island in Southern Italy, both characterized by intense hydro-geothermal phenomena in relation to their magmatic system dynamics [3; 4]. As results, chemical and structural modifications in the primary minerals and new mineral formations directly by gaseous emissions are produced. The FTIR data integrate high-resolution images by electron microscopy and microanalyses (SEM-EDS), X-ray diffraction (XRD) and rock-geochemistry as well.
Both Campi Flegrei and Vulcano has experienced low-magnitude eruptions in recent times (1538 and 1888-90 AD, respectively) and are characterized for typical sulfate alteration facies with a sulfur bearing and quartz-enriched central portion close to the gaseous plume, varying to advanced argillic and argillic facies moving outwards [1; 5]. Notably, in addition to S-bearing minerals, ammonium-sulfate, ammonium-chloride, borate, kaolinite and metals can be also detected.
At the Campi Flegrei the neogenesis is mainly related to hydrothermal and magmatic phenomena, and here we report peculiar mineral changes (ammonium-sulfate disappearance) and trace element compositions (among which Mo, As, Hg) occurring, particularly, during volcanic unrest episodes. FTIR provides detailed information on functional groups, used to trace alteration processes, and can be a further method to monitor the evolution of volcanic/hydrothermal fluids dynamics.
In the case of Vulcano Island, the element compositions of the sulfate geoderma point for major components of deep gaseous magmatic supply, for example more significant Te and similarly limited Se contents, coupled with Au [5].
In conclusion, we suggest FTIR as a useful tool to track mineralogical alterations and hydrothermal neogenesis at both Campi Flegrei and Vulcano Island contributing to deepen the knowledge of the dynamics of volcanic/hydrothermal processes taking place in these highly active geothermal settings. The obtained results are useful in the volcanic and environmental hazards associated with ongoing magmatic activities.
References:
[1] Piochi M. et al. (2019) Solid Earth Discuss., 10, 1809–1831
[2] Kolb, V. M., (2018) ed. Handbook of astrobiology. CRC Press.
[3] Giacomuzzi G. et al. (2024) Earth Planet. Sci. Lett., 637 (2024), Article 118744
[4] De Astis G. et al. (2023) Terra Nova, 35, 471–487
[5] Fulignati et al. (1998) J. Volcanol. Geotherm. Res., 86 (1-4) (1998), pp. 187-198
How to cite: Solomita, G., Piochi, M., Mormone, A., Balassone, G., and De Astis, G.: FTIR Spectroscopy analysis of Mineralogical Alterations facies at active Volcanoes : Vulcano and Campi Flegrei case studies, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11914, https://doi.org/10.5194/egusphere-egu25-11914, 2025.
Posters on site: Fri, 2 May, 10:45–12:30 | Hall X1
Lipari Island, the largest of the Aeolian Archipelago in the southern Tyrrhenian Sea, is a natural laboratory for investigating the intricate interactions between active volcanism, extensional tectonics, and hydrothermal processes. Spanning over 270,000 years of volcanic history, the island's evolution has been strongly influenced by the Tindari-Letojanni Fault System (TLFS), a major strike-slip fault that controls the emplacement of volcanic centers and the migration of hydrothermal fluids. Geological and geophysical studies, including ambient noise tomography (ANT) and high-resolution magnetic anomaly surveys, have revealed the complex subsurface structure of Lipari. High shear wave velocity (Vs) anomalies correlate with older volcanic buildings and active hydrothermal systems (e.g., San Calogero). At the same time, low Vs regions align with N-S trending faults, younger rhyolitic conduits, and ongoing volcanic processes. These findings highlight the crucial role of tectonics in shaping the island's geothermal and volcanic dynamics. Geochemical analyses further emphasize the influence of fluids in driving Lipari's hydrothermal systems. Elevated CO₂ fluxes, exceeding 2000 g/m²/day at key fault intersections, and distinctive isotopic signatures (e.g., helium and carbon) indicate a mantle-derived magmatic contribution to the hydrothermal activity. Sites such as Cave di Caolino and San Calogero demonstrate advanced argillic alteration, characterized by silica- and sulfate-rich minerals, driven by acidic steam condensates. This alteration reflects ongoing fluid-rock interactions and provides critical insights into the geothermal reservoirs' chemical and thermal conditions. Leveraging Sentinel-2 multispectral imagery, this study utilizes the Thermal Anomaly Index (TAI) to detect and quantify thermal anomalies across Lipari Island, overcoming the limitations of a dedicated thermal band. The TAI integrates Near Infrared (NIR) and Shortwave Infrared (SWIR) bands to identify moderate and extreme thermal variations associated with volcanic and geothermal activity. The SWIR 1 band is effective in detecting moderate heat anomalies, while the SWIR 2 band excels in capturing extreme thermal events, such as fumarolic activity and hydrothermal alteration zones. Enhanced Thermal Anomaly Indices (TAIE) further refine this analysis, enabling precise identification of active volcanic zones and areas under thermal stress, such as those prone to drought or water scarcity. Combining TAI-based thermal insights with geophysical and geochemical data identifies shallow basaltic intrusions as primary heat sources fueling Lipari's geothermal systems. These systems exhibit characteristics consistent with low-to intermediate-enthalpy geothermal reservoirs, with temperatures estimated between 170°C and 200°C. The TLFS is a primary conduit for fluid migration, facilitating geothermal fluid circulation and heat transfer. Such integrated findings underline Lipari's substantial potential for sustainable geothermal energy exploitation. This research advances our understanding of volcanic island processes by linking lithospheric-scale tectonics, hydrothermal circulation, and remote sensing methodologies. The insights gained hold significant implications for managing volcanic hazards and optimizing renewable energy resources, offering a robust framework for continuous monitoring and sustainable development.
How to cite: Pisciotta, A., Camarda, M., De Gregorio, S., and Riolo, G. M.: Integrating Multidisciplinary Approaches and Thermal Anomaly Indices to Advance Volcanic and Geothermal Insights on Lipari Island (Italy), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10470, https://doi.org/10.5194/egusphere-egu25-10470, 2025.
The surface flux of geothermal gases is driven by diffusion and advection, influenced by soil temperature, steam-heated ground, seismic activity, as well as seasonal or meteorological variations. Soil permeability, shaped by natural and anthropogenic processes, plays a key role in fluid migration, while hydrothermal fluid-solid interactions can alter permeability, affecting gas migration and surface release dynamics.
The Rotokawa geothermal field in New Zealand exemplifies how anthropogenic activities can modify natural surficial degassing processes. Ash- to pumice-rich Taupo ignimbrite units built the surficial layers in this geothermal field. In undisturbed areas, degassing occurs through the variably altered soil layers. Excavation induced by anthropogenic activities into the near-surface clay-rich horizons within the ash- to pumice-rich Taupo ignimbrite created new fumarolic areas, springs, and mud pools, while producing thick sulphur crusts and silica patina over time. As a result, in many excavated sites the areal permeability was reduced and the degassing concentrated along cracks. In undisturbed areas, degassing occurred through the variably altered soil layers.
This study integrates petrophysical and geochemical analyses to quantify permeability and gas flux across surficial soil layers. During a field campaign in February 2023, six vertical and three horizontal gas profiles were analysed by inserting a metallic rod into exposed soil and subsurface layers to extract and measure accumulated CO2, CH4, and H2O. The CO2 concentrations ranged from 432 to 99,370 ppm, CH4 from 2 to 754 ppm, and H2O from 23,514 to 41,555 ppm. Further we measured the vertical and horizontal permeability for key layers in these profiles. Samples of these key layers were taken for grain size and componentry analysis. Comparing the gas measurements with the petrophysical properties of the different soil layers provided insight into the vertical and lateral fluid movement and the influence of permeability in individual horizons. Our results enhance our understanding of how alteration and soil properties with and without anthropogenic influences affect geothermal gas emissions and will help improve future soil gas flux assessments.
How to cite: Davoli, R., Tamburello, G., Ricci, T., Montanaro, C., Murphy, B., Jones, T., Brooks, I., Cronin, S., and Scheu, B.: Impact of alteration and soil properties on geothermal gas emissions at Rotokawa, New Zealand, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18615, https://doi.org/10.5194/egusphere-egu25-18615, 2025.
SANTORY is a state-of-the-art project dedicated to advancing submarine volcanic hazard monitoring and risk mitigation in the Aegean Sea. Located in Kolumbo submarine volcano, northeast of Santorini Island, this groundbreaking observatory employs advanced imaging, geophysical and geochemical measurements, and real-time monitoring technologies to address one of the most significant volcanic threats in the region.
Over the past two years, SANTORY has provided unparalleled insights into Kolumbo’s geological dynamics and processes and potential hazards. High-resolution 3D mapping has identified steep slopes, mass-wasting deposits, and hydrothermal vent fields, crucial for assessing seafloor instability and the risks associated with eruptions and submarine landslides. Novel hyperspectral imaging and autonomous video systems have documented persistent hydrothermal venting, bubbling plumes, and environmental changes, offering a comprehensive baseline for tracking volcanic activity and geohazard precursors.
Autonomous sensors on the crater floor have continuously monitored hydrothermal outflow temperature, pressure, and fluid chemistry, capturing variations driven by tides and magmatic activity. These continuous datasets are critical for identifying precursor signals of volcanic unrest, such as changes in subsurface permeability and magmatic degassing. Chemical and isotopic analyses of hydrothermal fluids have confirmed the degassing of CO2-rich fluids with a mantle-like 3He/4He signature, underscoring Kolumbo’s potential for hazardous eruptions and its significance as a high-risk volcanic system.
SANTORY goes beyond scientific exploration; it is a transformative initiative aimed at improving volcanic hazard assessment and developing mitigation protocols. By integrating cutting-edge technologies and multidisciplinary expertise, the project delivers actionable insights to enhance early warning systems and protect vulnerable coastal communities.
How to cite: Katsigera, A., Nomikou, P., Polymenakou, P., Sciré Scappuzzo, S., Lazzaro, G., Mallios, A., Douskos, V., Rizzo, A. L., Longo, M., Escartin, J., Karantzalos, K., D' Alessandro, W., Heimburger, L.-E., Kilias, S., Mertzimekis, T., Grassa, F., Lampridou, D., and Anagnostou, E.: Two years of the SANTORY shallow seafloor observatory: Advancing submarine volcanic monitoring in the Aegean Sea (Greece), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5105, https://doi.org/10.5194/egusphere-egu25-5105, 2025.
Tenerife (Canary Islands) has undergone several lateral collapses, each followed by the regrowth of its edifice. In this context, the active stratovolcano Teide, in central Tenerife, has been regrowing following a north-directed collapse. Previous studies suggest that Teide continues to exhibit signs of potential flank instability to the north related to ongoing volcano spreading. This flank instability is thought to accelerate during magmatic and hydrothermal episodes. While outward displacement commensurate with spreading is not observed, morphological and structural features have still been linked to possible spreading. The volcano shows a concave slope profile on the northern flank, as well as normal faulting at the summit. These features may imply (1) a gently dipping low-strength breccia layer at the base of the volcano, facilitating large-scale spreading; and (2) the presence of a hydrothermally altered core and crater area later overgrown by the edifice. Here, we characterise the physical and mechanical properties of rock samples collected from (1) the pre-medieval Teide cone (Old Teide), (2) Old Teide’s crater rim, (3) Teide’s new summit cone, and (4) lava flows from Teide’s most recent summit eruption (Lavas Negras) using laboratory measurements of density, porosity, permeability, thermal conductivity, P-wave velocity, Young’s modulus, and uniaxial compressive strength. Combined with high-resolution drone imagery, these measurements provide critical data for computational models of large-scale volcano stability. This multidisciplinary study aims to test whether mechanical weakening from a hydrothermally altered core alone can cause the observed slope concavity, which would have significant implications for hazard assessment and monitoring of volcanic collapse events.
How to cite: Loisel, A., Harnett, C. E., Heap, M. J., James, D., De Jarnatt, B., González, P. J., Boulesteix, T., Walter, T. R., and Troll, V. R.: Rock physical properties and mechanical implications of a hydrothermal core within Teide volcano, Tenerife, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11815, https://doi.org/10.5194/egusphere-egu25-11815, 2025.
Steep slopes, excessive volcanic edifice volume, weathering and/or alteration generating weak substratum, and magmatic-volcanic or seismic activity are known factors that all control volcano flank instability. These factors are critical in generating volcanic debris avalanches, which are rapid-onset catastrophic events that can cause substantial damage to infrastructure and loss of life within minutes to hours. Despite this, volcano hazard maps of Andean volcanoes do not specifically incorporate analysis of zones or areas prone to flank collapse. In a new project (Fondecyt 11241126), we aim to determine the distribution and geometry of potential sites of flank instability, and their controlling factors, that may produce potential future volcanic debris avalanches at the Chillán Viejo (3,195 m asl) and Antuco (2,979 m asl) volcanoes. In 1883, the upper south-southeast flank of Chillan Viejo volcano collapsed after an eruptive cycle, producing a 600 m-length scar. Comparatively, at ca. 7 ka BP, the western flank of Antuco collapsed catastrophically, producing a 6.4 km3 debris avalanche deposit [1]. Rapid edifice growth and regeneration at both volcanoes demands the assessment of future flank collapse scenarios. In the field, we sampled representative lithological units of both fresh and hydrothermally altered rocks for petrological and geochemical characterisation. Simultaneously, we performed rebound tests in substratum units, lava flows, and intrusive bodies using N-type Schmidt test hammers. These measurements were complimented by the construction of three-dimensional outcrop models from Unmanned Aerial Vehicle surveys for structural analysis. The samples collected were analysed in the laboratory in order to constrain the physical and mechanical rock properties of both intact and hydrothermally altered blocks. Preliminary results are compared with textural and compositional features of the effusive products to better understand the mechanical behaviour of both volcanic edifices, identify potential sites of future collapse, and ascertain potential collapse drivers.
This is a contribution to Fondecyt iniciación 11241126 and the European Research Council (ERC) SYNERGY grant 101118491 "ROTTnROCK".
References:
[1] Romero, J. E., Moreno, H., Polacci, M., Burton, M., & Guzmán, D. (2022). Mid-Holocene lateral collapse of Antuco volcano (Chile): debris avalanche deposit features, emplacement dynamics, and impacts. Landslides, 19(6): 1321-1338.
How to cite: Romero, J. E., Heap, M. J., Polacci, M., Solana, C., Baud, P., Benson, P., Clunes, M., Browning, J., and Moulin, M.: Insights into flank instability from geomechanical assessment of fresh volcanic products at the Chillán Viejo and Antuco volcanoes (Southern Andes of Chile), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13512, https://doi.org/10.5194/egusphere-egu25-13512, 2025.
The Nevados de Chillán volcanic complex, located in the Southern Volcanic Zone of the Andes, is one of the most active volcanoes in Chile. Its most recent eruptive cycle began in 2016 and lasted seven years until January 2023, with a volcanic explosivity index (VEI) level 2. This sequence is the best instrumentally recorded eruption in Chile to date, encompassing small vulcanian eruptions, the formation of the new crater (called Nicanor), dome growth and collapse, effusion of lava flows, and seismic activity characterized primarily by long-period, tremor, and volcano-tectonic earthquakes.
To characterize the complete eruptive sequence, we integrated seismic, accurate position (GNSS) and radar interferometric (InSAR) observations. We calculated displacement time-series of the Sentinel-1 (C-band), ALOS-2, and SAOCOM-1 (both L-band) satellite missions, and identified three distinct phases of the eruptive cycle. The volcanic inflation caused a total of ~20 cm LOS range change between December 18, 2015, and March 1, 2024, that was preceded by a subtle deflation signal during 2017–2019. Maximum displacement of 25 cm observed between 2019 and 2022 in both InSAR and GNSS data coincided with an increased activity of long-period seismicity, and effusion of 0.01-0.02 km3 of andesitic lava flows. The volcano deflated afterwards with a rate of ~4 cm/yr between 2022 and 2024, marking the final stage of our observation cycle.
We inverted the InSAR data with a pressurized prolate spheroid spanning the inflation period and compared the results to the total GNSS displacement. Inversion results indicate that the deformation source is located at ~6.2 km depth. Due to the source depth, deformation is likely of magmatic origin, and only a fraction of the intruded volume fed the small lava flows, even accounting for magma compressibility. Post-eruptive deflation can also be explained by the same deformation source.
Our results indicate that the expected behavior for this eruption, such as large-scale ground deflation throughout the complete event, was not observed. Instead, the volcano inflated during 2019–2022, the period with the largest mass effusion, before decaying exponentially.
How to cite: Symmes-Lopetegui, B., Metzger, S., Delgado, F., Báez, J. C., Ruiz, S., and Cabrera, L.: Geodetic and Seismic Analysis of Magmatic Processes During the 2016–2024 Eruptive Cycle of Nevados de Chillán Volcanic Complex, Southern Andes., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8752, https://doi.org/10.5194/egusphere-egu25-8752, 2025.
The 2021 Fagradalsfjall dike intrusion marked the initiation of a new era of volcanism on Iceland’s Reykjanes Peninsula. In this study, we present a large automatic catalog consisting of more than 80,000 earthquake hypocenters spanning the full period of the dike intrusion, which were derived from seismic data recorded by a dense network of seismic stations. The 9 – 10 km long dike exhibits a two-segment geometry of similar lengths. Linear regression on a relatively relocated subset of over 12,000 earthquakes revealed a strike of 029° with a standard deviation of 2° in the southern segment, and 046° with a standard deviation of 1° in thenorthern segment of the dike. A total of 97 detailed fault plane solutions from relative relocations of selected subsets of events provide new insight into the controls on faulting, showing almost exclusively right-lateral strike-slip/oblique-slip faulting associated with the dike intrusion, and a lack of left-lateral strike-slip fault motion. The alignment of fault planes is consistent with the orientation of pre-existing fractures, within uncertainty estimates. In light of these observations, we conclude that the likelihood of faulting being related to classical dike tip fracture of new rock ahead of the dike tip is low. Instead, our preferred explanation for the dominant controlling factor on the orientation of dike-related faulting is the extensive network of pre-existing fractures formed by the active transtensional plate boundary along the Reykjanes Peninsula.
How to cite: Glastonbury-Southern, E., Winder, T., Rawlinson, N., White, R., Greenfield, T., Bacon, C., Águstsdóttir, T., Brandsdóttir, B., Gudnason, E. Á., Hersir, G. P., Fischer, T., Doubravová, J., Hrubcová, P., and Eibl, E. P. S.: Pre-existing structures control the orientation of strike-slip faulting during the 2021 Fagradalsfjall dike intrusion, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6155, https://doi.org/10.5194/egusphere-egu25-6155, 2025.
The behavior of temporally sequenced lateral dike intrusions into rift zones depend on intrinsic and extrinsic factors including the pressure build-up in the magma source and the local stress regime influenced by tectonic stress and topography. To reexamine the effects of these factors, we revised the simplified elastic model of rifting by Buck et al. (2006). In the revised model, topographic gradients and tectonic stress, in addition to magma accumulation, contribute to the driving pressure of dike propagation. In our model, dikes follow the positive gradient of driving pressure and open in the segment of the rift zone, where the local maximum driving pressure occurs, while available tectonic stress controls individual and total openings. A case study of the 1975–1984 Krafla rifting episode indicates repeated dike intrusions can be explained by a single magma inlet into the rift zone, located ~2–4 km north of the Krafla caldera center. An inferred magma pressure ~1–10 MPa above lithostatic stress at the inlet prior to the rifting episode generated the first and largest dike intrusion in the entire rifting episode, supported by >20 MPa of driving pressure from tectonic stress and topography. The case study indicates that the magma pressure at the initiation of the first dike is larger than that for later dikes by a factor of 2. The lower magma pressure to initiate later dikes, together with tectonic stress and magma compressibility, permits dike initiations when magma pressure at the inlet is below lithostatic. The model is also adapted to fit spatial distribution of dike openings in the 2023–2025 Svartsengi rifting episode in SW Iceland. In this case, inferred tectonic stress and significant magma buoyancy effects (~15 MPa) enable dike initiations with the magma pressure at the inlet below lithostatic, while topographic effects contribute ~2 MPa more of driving pressure to the southern propagation of the first dike intrusion. Tectonic stress also inhibited eruption from the initial dike of the Svartsengi rifting episode. Our findings demonstrate that tectonic stress and topographic effects are critical factors driving lateral dike propagation in an extensional plate boundary, allowing magma flow into dikes or eruptions under relatively low magma pressure, including magma pressure below lithostatic.
How to cite: Yang, Y., Sigmundsson, F., Geirsson, H., and Gottsmann, J.: Role of tectonic stress and topography on repeated lateral dikes: case studies from the 1975–1984 Krafla and 2023–2025 Svartsengi rifting episodes in Iceland, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13373, https://doi.org/10.5194/egusphere-egu25-13373, 2025.
The Reykjanes Peninsula (Iceland) has been experiencing an oblique rifting episode since 2019. Intense and repeated earthquake swarms (magnitude up to ML~5) and ground shaking accompany the deformation of the region. Magma accumulation in crustal reservoirs and discharge to dikes and eruptive fissures actively participate in the tectonic crisis. The crisis is accompanied by fault offsets and slope instabilities, generating hazards that have not yet been systematically investigated. Using photogrammetry, digital image correlation and seismicity data, we analyse the rockfall activity (442 events mapped) and fault kinematics (up to 0.8 m offset) from Mount Þorbjörn (Thorbjoern) between 2019 and 2024. We find a positive correlation between the timing of rockfall events and earthquakes with energy density (estimated seismic energy that could generate a rock block displacement at a given location) larger than ~1 J/km3 at Mount Þorbjörn's summit. We propose that this energy density is sufficient to trigger rockfall events at steep slopes on the Reykjanes Peninsula. The seismic energy density for steep terrains could allow a quick assessment of the potential for rockfall activity after earthquakes.
The novel strategy to measure ground displacement using high-resolution and high-precision unmanned aerial vehicles presented here, adapted from several existing state-of-the-art methods (Post-Processing Kinematics, 3D point cloud correlation, 2D terrain correlation, mapping on orthophotos), enables the detection and kinematic characterisation of previously unmapped structural features and rockfall events. Multiple NS and NNE-SSW-oriented faults were reactivated in a right-lateral sense of motion, with up to 40 cm offsets. The graben faults dissecting the mountain were reactivated multiple times, with up to 80 cm vertical offsets in the centre of the graben. The methodology described here can serve various applications in research, industry, and local emergency management services after future seismic crises.
How to cite: Oestreicher, N., Hurley, M., Sæmundsson, Þ., Panza, E., Shevchenko, A. V., Luo, X., Bufféral, S., Walter, T. R., Einarsson, P., Geirsson, H., and Ruch, J.: Consequences of mountain shaking during the 2019-2024 oblique rifting episode at Mount Þorbjörn, Reykjanes Peninsula, Iceland, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18214, https://doi.org/10.5194/egusphere-egu25-18214, 2025.
The primary objective of this study is to detect and analyse subsurface density variations that could indicate magmatic movements or other geological processes associated with volcanic activity in the Canary Islands. Microgravimetry is a geophysical technique that measures spatial and temporal variations in the Earth's gravitational field over its surface, allowing the detection of density changes within the crust. For this reason, it is a valuable technique in volcano monitoring, capable of detecting changes in a volcanic-hydrothermal system. This information is crucial for understanding the dynamics of volcanic systems and assessing potential volcanic hazards. Microgravity surveys involve precise gravitational field measurements along closed circuits across the islands. By comparing these measurements over time, we can identify local changes in the gravity field that may correspond to subsurface movements of magma or other density changes.
This work is focused on the volcanic islands of Tenerife, La Palma, Lanzarote, and El Hierro in the Canary Islands archipelago. These islands have experienced significant volcanic activity in the past centuries, making them ideal targets for using microgravity surveys as a volcano monitoring tool. In this study, we conducted extensive surveys, collecting gravity data at numerous stations across the four islands. We realised periodic surveys consisting of 78 points in Tenerife, 22 points in La Palma, 7 points in Lanzarote and 19 points in El Hierro. The average spacing between measurement points is about 1.5 km in Tenerife and 2 km in the other islands. Field surveys are performed every 2 months in Tenerife and La Palma and every 6 months in the other islands.
Data are processed to correct the effects of tides, elevation and Bouguer anomalies and analysed to identify significant gravimetric anomalies. We created anomaly maps using Kernel Density interpolation, considering the differences between gravimetric values from one and a reference campaign. These maps visually represent the spatial distribution of gravimetric anomalies and enhance our understanding of the subsurface processes.
Applying microgravity surveys in volcanic regions like the Canary Islands offers an effective method for monitoring volcanic activity. This technique can complement other geophysical methods, such as seismic and geodetic measurements, to comprehensively understand volcanic processes. The results of this study contribute to the development of early warning systems for volcanic eruptions, ultimately aiding in the protection of local communities and infrastructure.
How to cite: Álvarez Hernández, A., D'Auria, L., García Hernández, R., Martínez van Dorth, D., Ortega Ramos, V., Páez Padilla, J., Prieto González, D., and Pérez, N. M.: Microgravity Surveys for Volcano Monitoring in the Canary Islands, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15847, https://doi.org/10.5194/egusphere-egu25-15847, 2025.
Volcanic flank instability poses a significant geohazard, particularly in oceanic island settings. Since September 2023, the VolcaMotion project has been investigating the mechanisms and timing of volcano flank instability across the Macaronesian archipelagos (Cape Verde, Canary Islands, and Azores), integrating geological, geochronology and geophysical data. We combine detailed geological structural mapping of exposed volcanic edifices with high-resolution topographic surveys, including ground deformation monitoring, to study both active and past deformation patterns. This approach allows us to characterize shear/dilation fault and fracture networks and potential slip surfaces associated with flank instability. In October 2024, we carried out the first field campaign aiming to better constrain better volcano-tectonic structures and geochronology in El Hierro (Canary Islands). In this communication, we present the overall objectives and approach of the VolcaMotion project, as well as the preliminary results after completing its first year. Using a multi-disciplinary approach, the VolcaMotion project will generate, over the next few years (2023-2027), a comprehensive understanding of volcanic flank instability processes in diverse geological settings and contributes and thus contribute to improved risk mitigation strategies for coastal communities in the Macaronesian archipelagos.
How to cite: Gonzalez, P. J., Charco, M., Boulesteix, T., Garcia-Pallero, J. L., Jurado, M. J., Eff-Darwich Peña, A., Webb, A., Gregory, L., Hildenbrand, A., Sansosti, E., Reale, D., and Solé, J.: The VolcaMotion project: Integrating Geophysical, Geological, and Geochronological Data to understand Flank Instability of Macaronesian Volcanoes, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6776, https://doi.org/10.5194/egusphere-egu25-6776, 2025.
Vulcano is a composite volcanic edifice representing the southernmost emerged island of the Aeolian archipelago (Tyrrhenian Sea, Italy). Grown at the convergence of the Africa and Eurasian plates, Vulcano is part of a complex volcano-tectonic system characterized by a NNW-SSE fault system which controls the volcanism evolution of the Aeolian central branch and its continuous long-term deformation. Vulcano experienced many eruption episodes in historical times, the most recent of which occurred in 1888-1890. Since then, it has undergone repeated phases of unrest characterized by shallow seismicity, increased fumarolic activity, and sometimes ground deformation. The most recent unrest episode occurred from the summer till the end of 2021 with intense fumarolic activity mainly concentrated at La Fossa cone and some sectors of the caldera.
Long-term tectonic movement and unrest phases cause measurable deformation which can provide important insights into the volcanic system behavior. In this work we leveraged two types of satellite-geodesy deformation data: GNSS and InSAR. We considered the time series of 6 continuous GNSS stations managed by the Osservatorio Etneo of INGV. The SAR dataset consists of Sentinel-1A images acquired from January 2016 to December 2023 along ascending and descending orbits, and processed through the Interferometric Point Target Analysis (IPTA) approach to retrieve ground deformation velocity and displacement time series.
Focusing on the 2016-2023 interval, we first validated the InSAR results with GNSS data, obtaining a general good agreement. The GNSS time series clearly show different phases of deviation from the long-term linear trend, particularly in 2018 and 2021. The 2021 period is associated with up to about 2 cm uplift and 1 cm of nearly radial pattern around La Fossa caldera. InSAR data are noisier, but also show transient signals, with a clear signal in 2021, associated with an elliptical deformation area of up to about 3 and locally 5 cm in Line of Sight at La Fossa caldera.
InSAR and GNSS data provide complementary information respectively about the near- and far-field deformation pattern associated with the 2021 unrest phase. We jointly inverted these data using a new modeling algorithm implementing elastic and inelastic (thermo-poroelastic) sources to retrieve the volcanic source of the ground deformation observed during the recent unrest phase. Results indicate as preferred model a spheroid/cylindrical source located below La Fossa cone, with cumulated volume and pressure variations in agreement with previous studies using only InSAR or GNSS data. We also analyzed the 2018 deformation through GNSS data, whose pattern reveal an additional unrest episode possibly located at the northern edge of La Fossa Caldera. We discuss the highlighted unrest episodes in the context of the more general volcano-tectonic deformation pattern affecting the island.
How to cite: Silverii, F., Trasatti, E., Polcari, M., Nespoli, M., De Astis, G., Palano, M., and Tolomei, C.: Volcanic unrest episodes at Vulcano, Aeolian Islands (Italy), monitored by InSAR and GNSS, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6302, https://doi.org/10.5194/egusphere-egu25-6302, 2025.
Mount Etna, one of Europe's most active volcanoes, has experienced a variety of eruption settings throughout its history, including summit, flank, and eccentric eruptions. In this study, we provide a detailed analysis of the structures formed during the 1947 eruption, which occurred along the NE Rift, drawing on historical accounts, archival images, and contemporary field and drone data. Photogrammetric processing of 1932 and 1954 historical aerial photos enabled us to identify and map the structures formed before and during the eruption, in order to focus the effects of the direction of the dyke propagation, and of pre-existing fractures on the 1947 deformation pattern. Several data collected through recent field missions allowed us to classify the structures into different types including extensional fractures, normal faults, and eruptive fissures, and to determine their kinematics (pure extensional, right-lateral component, and left-lateral component). We also extracted information on the structures' length, azimuth, vertical offset, vectors and opening amount, to characterize the surface deformations resulting from the magmatic event. Furthermore, we reconstructed a detailed chronology of the eruption's day-by-day development based on available historical data. This information allowed us to characterize the event as a lateral propagation of magma along a N-S to NE-SW-striking dyke. This produced the formation of various structures, with different geometry and deformation amount. In particular, our reconstruction of the fault-slip profiles obtained at both sides of multiple grabens, show that fault scarps taper towards NE. This is consistent with the assumption that lateral dyke propagation can induce the formation of normal faults with asymmetric slip profiles.
How to cite: Luppino, A., Tibaldi, A., Cantarero, M., Corti, N., De Beni, E., Pasquarè Mariotto, F., and Bonali, F. L.: Effects of lateral dyke propagation and pre-existing fractures on dyke-induced deformation: field data from the Etna 1947 eruption, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10886, https://doi.org/10.5194/egusphere-egu25-10886, 2025.
Mount Etna experienced a remarkable eruptive cycle between 2020 and 2022. In December 2020 the South East Crater —one of Etna’s four main craters and the most active over the last 25 years— started exhibiting a series of paroxysmal events characterized by strong, short bursts of lava fountaining accompanied by increased seismic activity. This eruptive period intensified in February 2021 and continued until the end of March (Sequence 1). After a brief pause, a second paroxysmal period began in May 2021 continuing until October 2021 (Sequence 2). The last paroxysms of this cycle were observed in February 2022. A total of 64 events occurred between December 2020 and February 2022.
To investigate the ground deformation patterns and magmatic processes associated with these paroxysmal sequences, we integrated GNSS, InSAR, and petrological analysis (Corsaro et al., 2024). The eruptive sequences showed markedly different characteristics in terms of magma supply rates, eruptive styles, and ground deformation patterns. Sequence 1 was characterized by higher magma supply rates, larger erupted volumes, progressive mixing with deeper magma corresponding to larger paroxysms and dominant lava effusion. In contrast, Sequence 2 exhibited lower supply rates, more frequent but smaller paroxysms, a gradual trend from evolved toward primitive compositions together with prevalent explosive activity (Corsaro et al., 2024 and references therein). According to InSAR and GNSS time series, the volcano edifice experienced inflation during most of 2020, followed by a period of intense and continuous deflation, matching the occurrence of 17 lava fountain episodes during the first sequence. A second deflation trend is observed during the second paroxysmal sequence, although with reduced deformation intensity. The 48-day repose period between both sequences is interpreted as a critical phase in which conditions within the shallow reservoir changed, thereby facilitating the transition from predominantly effusive activity in Sequence 1 to more explosive behavior in Sequence 2. This period likely introduced increased complexity, manifesting not only in the potential magmatic processes during the second sequence, but also in the modeling of the associated deformation source.
Our analysis provides insights into how variations in magma storage conditions can influence both ground deformation patterns and eruptive styles. Furthermore, the joint analysis highlites the potential of integrating geodetic and petrological data for a more comprehensive understanding of the dynamics of Mount Etna’s magmatic system and its magma charging regime.
How to cite: Vásquez Castillo, A., Corsaro, R. A., Gugliemino, F., Puglisi, G., Bonforte, A., and Cannavò, F.: Characterizing Paroxysmal Sequences at Mount Etna by Integrating Geodetic and Petrological Analysis, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19222, https://doi.org/10.5194/egusphere-egu25-19222, 2025.
Over the past two decades, Campi Flegrei caldera has experienced persistent ground deformation, paired with increasing seismic magnitudes and rates since 2015. Recent geodetic and seismic measurements reveal a significant increase in uplift rates, shedding light on the spatial and temporal deformation patterns. The effects of magma transport on the measured deformation have been discussed, along with the presence of shallow gas and fluid accumulation, which also play a critical role in building the pressure up. Understanding the source of the observed deformation and seismic activity requires integrating diverse geophysical observations into geodynamic modeling, which provides crucial insights into the geophysical response of coupled tectonic and magmatic processes.
Joining the interpretations from seismic imaging, geodetic observations, and rock physics, we perform thermo-mechanical modelling of the Campi Flegrei magmatic system using the Lithosphere and Mantle Evolution Model (LaMEM) code, which takes into account visco-elasto-plastic rheologies. Employing the available structural information on the caldera, such as a caprock layer and a hydrothermal system, the 3D thermo-mechanical numerical simulations account for the realistic topography and a deep crustal magma migration from an ∼8 km deep magma sill to a magma reservoir at ∼ 5 km depth. Our approach also considers shallow gas and fluid accumulation, investigating the interaction between deep magma dynamics and overlying structures. The modelling results show how structural complexity influences the symmetry and amplitude of the deformation patterns and whether deep magma migration should be paired with the effect of shallow structures and rheologies. The findings suggest that integrating additional geophysical constraints could significantly improve our understanding of the deformation source and evolution of stress fields for future modelling of seismic responses. This integrated approach advances our comprehension of tectonic-magma interactions at Campi Flegrei caldera.
How to cite: Nardoni, C. and De Siena, L.: Thermo-Mechanical Modeling of Deformation Processes Driving Seismicity at Campi Flegrei Caldera, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10509, https://doi.org/10.5194/egusphere-egu25-10509, 2025.
Campi Flegrei is the largest active urbanized caldera in Europe. Since 2005, it has shown slow but progressive ground inflation and, in recent years, an increase in seismic activity. Deformation is characterized by transient reversals in rate, leading to episodes of monotonic uplift lasting from several weeks to a few years. Additionally, some aseismic transients have been detected using high-sensitivity strainmeters and long-baseline tiltmeters, with amplitudes typically below the noise level and durations shorter than the sampling frequency of most geodetic techniques. A shallow hydrothermal origin for the ongoing deformation may explain non-eruptive cycles of subsidence and uplift, driven by the balance between magmatic input and fluid discharge at the surface. However, separating signals from magmatic and hydrothermal sources is challenging due to the presence of both types of reservoirs. A detailed study of ground deformation using a finite element model is essential to understand the kinematics of both the aquifer and the plumbing system at different depths. In this study, we used COMSOL Multiphysics to examine how deep pressure and temperature changes influence surface deformation in the Campi Flegrei caldera. The Tough software, simulating multi-phase fluid and heat flows, was used to model the sources which, within the COMSOL model, hasshown a good match with observed surface deformation data from GPS/GNSS and strainmeter time series, confirming the model’s accuracy. Combining data and models makes it more feasible to forecast volcanic system parameters on relevant timescales.
Data used contains valuable information for scientific community,following EPOS policies.
How to cite: Romano, P., Di Lieto, B., Mangiacapra, A., Petrillo, Z., and Sangianantoni, A.: FEM model of surface deformation pattern applied to the Campi Flegrei caldera, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20103, https://doi.org/10.5194/egusphere-egu25-20103, 2025.
Whakaari (White Island) volcano is the most active volcano in New Zealand and has caused some of the deadliest volcanic eruptions in the country’s history. The volcano has a dynamic hydrothermal system and has had 4 eruptive periods since 2016 with the most recent period still ongoing. In this study, we aim to understand the pre-and post-eruption deformation processes occurring at Whakaari using interferometric synthetic aperture radar (InSAR). We analyze Sentinel-1 Bursts spanning the period 2014 to 2024 from 3 different tracks (1 ascending and 2 descending) using small baseline subset (SBAS) InSAR time-series analysis. Three stacks are analyzed spanning the periods (a) 2014 to 2024, (b) 6 months before and after the 2016 eruptions, and (c) 6 months before and after the 2019 eruption. Initial results show several phases of uplift and subsidence spanning the entire period. These phases of observed vertical displacement also vary spatially among the western, central, and eastern sub-craters. These results will be discussed in the context of the long-term deformation rates at Whakaari over the last decade as well as short-term pre- and post-eruptive processes focused on the 2016 and 2019 eruptions. Results will help understand precursory deformation processes at active volcanoes and the use of InSAR as a potential monitoring tool.
How to cite: Essenmacher, S. and Kanakiya, S.: Characterizing spatiotemporal ground deformation at Whakaari (White Island) volcano, New Zealand, using InSAR time-series analysis, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7224, https://doi.org/10.5194/egusphere-egu25-7224, 2025.
The onset of large caldera forming eruptions is commonly associated with pre-, syn- and post-collapse volcanism along the previously formed ring faults. This collapse mechanism results on a caldera that spans the entire extent of the magma chamber as the ring faults are thought to localise at the margins of the chamber. Whilst larger calderas have been extensively researched, with numerical models providing a robust understanding of the driving forces, smaller systems (≤ 5 km in diameter) can also produce caldera-forming eruptions. Prominent examples include Krakatau (Indonesia) and Crater Lake (USA). Pre- and post-collapse volcanism is typically associated with a central vent eruption at a volcanic edifice.
In this study, we employ the thermo-mechanical geodynamic code JustRelax.jl to investigate the mechanics behind central vent eruptions that trigger caldera collapses. The models use a non-linear visco-elasto-viscoplastic rheology, magma dynamics of a pre-existing shallow magma chamber of various geometry, far-field tectonic stresses and a central conduit structure that connects the magma chamber with a volcanic edifice. We utilise a dynamic conduit density parametrisation that accounts for the nucleation of bubbles when the magma rises to the surface through a gas solubility constant and total volatile content. The dynamic conduit density parametrisation facilitates the emulation of magma upward flow and progressive chamber depletion. This framework enables investigation into the governing underlying processes of central vent-driven caldera formation. We present a systematic parameter study on the driving forces behind this type of caldera collapse.
How to cite: Aellig, P., de Montserrat, A., Kaus, B., and Schuler, C.: Caldera collapse triggered by central vent eruptions - A numerical study, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10202, https://doi.org/10.5194/egusphere-egu25-10202, 2025.
Caldera collapse dynamics result from complex interactions involving multiple parameters, affecting surface deformation style, internal structural development, and structural style transitions. Furthermore, calderas are not only prominent features in volcanic environments, bearing intrinsic scientific significance, but they also represent a primary source of risk during periods of unrest, as well as a critical target for geo-resources (e.g., geothermal energy). For these reasons, understanding caldera collapse dynamics is of paramount importance for risk assessment and mitigation, as well as for understanding the evolution of volcano-tectonic systems.
We investigate caldera collapse dynamics through controlled laboratory experiments. Collapse is simulated in a granular material by draining an analogue magma (Polyglycerine-3) from an analogue magma chamber, with dynamic parameters (e.g., pressure) monitored using laboratory-scale geophysical sensors. The coupling between “classical” analysis (i.e., photogrammetric reconstruction of the model surface to quantify 3D deformation, structural line drawing, and PIV analysis) and geophysical data allows for the identification of a critical transition between inverse and normal faulting within the granular volume. While the magma discharge process maintains a consistent flow rate, overall fault propagation is influenced by this transition, leading to variations in caldera morphology. Our findings suggest that the evolving stress field significantly impacts faulting behavior, revealing the intricate relationship between internal fault mechanisms and surface collapse. This may provide a new way to compare analogue data with natural systems and enhances our understanding of caldera collapse dynamics, offering valuable insights into similar phenomena in volcanic environments.
How to cite: Maestrelli, D. and Sánchez Á., C. P.: A dynamic study of caldera collapse: Insights from analogue models and geophysical data, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9714, https://doi.org/10.5194/egusphere-egu25-9714, 2025.
We present a detailed study of the volcanotectonics in the Lesser Caucasus compressive belt, analysing 744 Quaternary monogenetic volcanoes using structural and geophysical field data. The study focuses on the interplay between tectonics and volcanism within this compressional setting. We analysed only volcanoes formed on horizontal or subhorizontal substrates, excluding those on the flanks of polygenetic volcanoes. For 394 volcanoes, we identified the underlying magma-feeding fractures based on volcanotectonic morphometric parameters. We also examined the spatial relationships between volcanoes and Quaternary faults, calculating the distance of each cone from the nearest main fault and considering fault kinematics. Furthermore, we correlated the azimuths of magma-feeding fractures with fault geometry, kinematics, GPS motion data, and focal mechanism solutions for shallow earthquakes.
The study reveals that most volcanoes are located more than 1 km away from regional Quaternary faults, suggesting these faults are not the primary conduits for shallow magma migration. Volcanoes near normal and strike-slip faults sometimes align with fault traces, confirming these faults can guide magma to the surface. The highest cone densities are linked to strike-slip faults, with magma pathways generally aligning WNW-ESE and NNE-SSW. Within tectonic blocks near strike-slip faults, magma-feeding fractures often deviate obliquely.
Magma can reach the surface also in contractional settings characterised by reverse faulting. In this case, no cones are within 200 m from reverse faults, indicating that magma can follow reverse faults at depth but migrates upward via secondary splays near the surface. Local structures formed by tectonic or magmatic stresses and self-generated hydrofractures from dyke overpressure also contribute to magma ascent, with hydrofractures aligned perpendicular to σHmin, depending on the stress regime.
Our findings emphasize that regional Quaternary faults are not the dominant pathways for shallow magma ascent in the Lesser Caucasus. Instead, magma utilizes local fractures within major tectonic blocks and self-generated hydrofractures. We also conclude that shallow magma paths are not necessarily always perpendicular to the least principal stress σ3, especially in the case of pre-existing mechanical discontinuities, suggesting caution in the use of volcano alignment or cone elongation (and similar morphometric parameters) to extrapolate stress orientations.
How to cite: Bonali, F. L., Corti, N., Bressan, S., Tsereteli, N., and Tibaldi, A.: Monogenetic Volcanism in Compressional Tectonics: Insights from the Lesser Caucasus (Georgia, Armenia, Azerbaijan), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9835, https://doi.org/10.5194/egusphere-egu25-9835, 2025.
Posters virtual: Tue, 29 Apr, 14:00–15:45 | vPoster spot 1
EGU25-20387 | Posters virtual | VPS22
Gas hazard assessment at the hydrothermal system of Baia di Levante at Vulcano Island during the 2021-23 unrest of La Fossa crater (Aeolian Islands, Italy)Tue, 29 Apr, 14:00–15:45 (CEST) | vP1.6
Vulcano Island in Aeolian Archipelago last erupted in 1888-1890 and since then it is affected by an intense fumarolic activity from both the summit crater area of La Fossa volcano and by the hydrothermal system of Baia di Levante located very near to the main settlement of Vulcano Porto. Ordinary solfataric activity is periodically interrupted by unrest crisis at La Fossa crater associated with increase in fumarole temperature and output, anomalous seismicity, ground deformation and accompanied by an increase in diffuse soil CO2 degassing at Vulcano Porto. In Autumn 2021 a new major unrest crisis began exposing to a high gas hazard Vulcano Porto settlement due to contemporary dispersion of crater fumarolic plume and diffuse soil CO2 degassing; Starting from February 2022, with apex in May, a huge increase in gas output of the geothermal system of Levante Bay was observed. The Baia di Levante area is characterized by the presence of a low-temperature fumarolic field (<100°C) either onshore and offshore and fed by a shallow hydrothermal aquifer heated by magmatic gases. A wide diffuse soil CO2 degassing area extends all over the main beach. The chemical composition of bubbling gases is CO2-dominant, associated with a 1-3 vol.% of H2S and minor CH4 and H2. The Bay is one of the main sites of attraction for the thousands of tourists who visit the island and given the increased risk for gas emissions and possible phreatic eruptions (due to overpressuration of the geothermal aquifer) we carried out some extraordinary geochemical surveys. These consisted of (i) estimation of diffuse soil CO2 flux over a target area (154 points over 16,750 m2) established since 2004; (ii) estimation of the convective CO2 and H2S flux (the main hazardous gases) from the onshore (50 points in the Mud Pool and surrounding areas) and offshore gas vents (2 main large vents and 60 small vents); (iii) Repeated measurements of the chemico-physical parameters (temperature, pH, Eh, conductivity and dissolved O2) in the Baia di Levante sea water (107 profiles; water depth from 50cm to 12m). In particular we investigated the areas characterized by the presence of whitish waters, trains of gas bubbles, emissive vents. Results shown significantly increased values compared to the past of the total CO2 and H2S output (diffuse and convective) measured on land and at sea surface. The sea water shows the presence of a wide anomalous pH in the near-shore sector between Faraglione and Vent 1 and to a lesser extent to the N of the bay. A wide anomaly of negative Eh values persist at all depths in almost all of the bay. A huge emissions of acid gases from the increased submarine fumaroles alter the chemical-physical parameters of the sea water along the bay. Considering the increased gas hazard the adoption of risk prevention measures was suggested to authorities.
How to cite: Ranaldi, M., Carapezza, M. L., Tarchini, L., Pagliuca, N. M., Pruiti, L., and Sortino, F.: Gas hazard assessment at the hydrothermal system of Baia di Levante at Vulcano Island during the 2021-23 unrest of La Fossa crater (Aeolian Islands, Italy), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20387, https://doi.org/10.5194/egusphere-egu25-20387, 2025.
EGU25-10890 | Posters virtual | VPS22
Unveiling the geochemistry of fluids in the Central Aeolian Islands (Italy)Tue, 29 Apr, 14:00–15:45 (CEST) | vP1.7
In the last decades, the volcanically active Aeolian Islands have been the focus of numerous geochemical investigations and monitoring activities, primarily focused on the islands of Vulcano, Stromboli and Panarea. However, relatively few studies have explored the geochemical characteristics of other islands, despite evidence of hydrothermal activity. Salina, for instance, hosts a shallow, cold, low-salinity aquifer that overlies a deeper warmer aquifer, with highly saline water. Additional noteworthy features include hydrothermal deposits on the seafloor and offshore submarine gas emissions. Similarly, Lipari hosts a thermal aquifer (e.g. Terme di San Calogero) and exhibits significant hydrothermal emissions along its western coast, particularly in areas of Valle del Fuardo and Caolino quarry. In this study we conducted detailed geochemical surveys on Lipari and Salina to investigate the origins of the fluids and their relationship with the geodynamic framework. The research is part of the Project CAVEAT (Central-southern Aeolian islands: Volcanism and tEArIng in the Tyrrhenian subduction system), which aims to provide a comprehensive understanding of the current geodynamics in the southern Tyrrhenian region, focusing on the interaction between volcanism and tectonic activity within the Tyrrhenian subduction system.
On Salina and Lipari islands, soil CO2 flux measurement campaigns were conducted to examine the spatial distribution of soil CO2 emissions. Thermal surveys using an Unmanned Aircraft System were conducted over fumarolic areas to detect thermal anomalies associated with zones of preferential fluid emissions. These measurements helped define preferential pathways for fluid migration and identify active tectonic structures associated with areas of elevated soil CO2 emissions. At selected sites, isotopic composition of gas was analyzed to infer the gas origins. On Lipari, soil CO2 emission anomalies revealed a NNW-SSE alignment consistent with the area’s primary tectonic structures. Isotopic analysis confirmed a contribution of deep-origin fluids to these emissions. Thermal (up to 45.8 °C) and cold waters from Salina and Lipari were sampled and analyzed for their chemical and isotopic composition, as well as for dissolved gases. The isotopic composition of the water clearly indicates that the sampled groundwater originates from a mix of meteoric water and seawater, with varying degrees of mixing at each site. Gases dissolved in water exhibit an atmospheric component with a high content of CO2 in the most brackish samples. At Salina, the isotopic composition of dissolved helium reflects a mantle contribution. Collectively, the findings emphasize the significant influence of mantle and deep-origin origin fluids in shaping the geochemistry of both islands. They further highlight the critical role of geodynamic and tectonic processes in governing fluid emissions across the two islands.
How to cite: Camarda, M., De Gregorio, S., Liotta, M., Di Martino, R. M. R., Oliveri, Y., Palano, M., Pisciotta, A., Riolo, G. M., and Romano, P.: Unveiling the geochemistry of fluids in the Central Aeolian Islands (Italy), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10890, https://doi.org/10.5194/egusphere-egu25-10890, 2025.
EGU25-20524 | ECS | Posters virtual | VPS22
Carbon dioxide emissions and fate from Vailulu’u seamount mapped using SAGE, a new in situ optical sensorTue, 29 Apr, 14:00–15:45 (CEST) | vP1.25
Vailulu’u seamount, located at the eastern extent of the Samoan hotspot chain, is an active deep-sea volcano with strong hydrothermalism and a recent history of eruptive episodes. Since 1999, a cone more than 500 m in diameter and with height greater than 300 m has formed within the caldera, while hydrothermal vent fields are known throughout the basin. These include regions of diffuse venting, substantial microbial mat formation, and chimneys emitting buoyant plumes of gas bubbles that are dominated by carbon dioxide. Measurements of turbidity and chemical enrichment in the caldera, temperature anomalies, and tracer dye studies have all previously been used to estimate and model the hydrothermal exports from this active volcano. Biological observations across the caldera – including the prevalence of carcasses in the so-called “Moat of Death” surrounding the Nafanua cone – have been used to infer the impact and fate of these volcanic emissions. However, it has previously been challenging to acquire high resolution in situ measurements of the discharged carbon dioxide at Vailulu’u, with the gas composition and distribution instead being determined primarily from discrete samples.
We present here a comprehensive spatiotemporal study of the carbon dioxide discharge from across the Vailulu’u seamount, acquired using SAGE, a new in situ carbon dioxide sensor. SAGE – the Sensor for Aqueous Gases in the Environment – was developed at Woods Hole Oceanographic Institution to quantify the concentration of dissolved gases in the deep sea. Dissolved gases are extracted across a gas-permeable membrane and into a hollow core optic fiber, which acts as an absorption cell for infrared absorption spectroscopy. SAGE has both a low detection limit (ca. 10 ppm) and a fast time response time (1-5 minutes). During a cruise on EV Nautilus in September 2024, SAGE was deployed on ROV Hercules and AUV Sentry to acquire high-resolution spatiotemporal maps of the carbon dioxide discharges from Vailulu’u. Comprehensive analysis of the hydrothermal exports from the vent fields on the rim allow estimation of the fate and flux of these discharges. Surveys from the caldera provide chemical context for the so-called “Moat of Death” and evidence for a significant diffuse venting across the Nafanua cone. To the best of our knowledge, this is the first study using in situ sensing of carbon dioxide at Vailulu’u.
How to cite: Burkitt-Gray, M., Youngs, S., Marquardt, S., Remar, J., German, C., Soule, A., Kapit, J., and Michel, A.: Carbon dioxide emissions and fate from Vailulu’u seamount mapped using SAGE, a new in situ optical sensor, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20524, https://doi.org/10.5194/egusphere-egu25-20524, 2025.
