In recent years, seismic imaging has emerged as a powerful tool to investigate volcanic systems, providing constraints on plumbing structures, eruptive products, and associated mass-wasting processes across a wide range of spatial and temporal scales. Advances in seismic tomography enable imaging of magmatic systems from crustal mush zones to shallow, melt-rich reservoirs. Meanwhile, high-resolution reflection seismic methods reveal the shallow architecture of volcanoes, including internal stratigraphy, intrusive networks, pyroclastic flow deposits, and collapse-related features. These complementary approaches not only illuminate past eruptive and mass-wasting events but also provide insights into the current stability of volcanic flanks. The integration of seismic methods across scales therefore offers a unique opportunity for a holistic understanding of volcanic systems and for developing more robust hazard assessments.
This session welcomes contributions that apply earthquake seismology or controlled-source seismic data (from land or marine settings) to the study of modern or ancient volcanic systems. We particularly encourage studies that combine multiple approaches or datasets to advance our understanding of volcanic architecture, evolution, and associated hazards.
Understanding the crustal structure and magma migration pathways beneath Mt. Etna (Italy) is crucial for volcanic hazard assessment. While isotropic seismic models successfully image major velocity anomalies beneath the volcano, they often neglect the significant seismic anisotropy generated by aligned fractures, fault systems, and magmatic bodies, potentially biasing interpretations of the volcanic plumbing system. This work presents the first comprehensive 3D P-wave anisotropic tomography of Mt. Etna, obtained from the inversion of local earthquake P-wave travel times assuming a transversely isotropic medium with an arbitrarily oriented symmetry axis. By simultaneously recovering isotropic velocities and three anisotropic parameters (magnitude, azimuth, and dip), the inversion allows for a more physically consistent imaging of the crustal volume beneath Mt. Etna. The model reveals a high-velocity complex in the central-southern sector of the volcano, characterized by a distinctive anisotropic signature with slow axes arranged in a near-circular pattern. This configuration is interpreted as a system of radial fractures and dykes associated with the emplacement of solidified magmatic bodies. At greater depths, a high-velocity volume deepening toward the northwest corresponds to the Hyblean foreland crustal units, which confine a low-velocity anomaly interpreted as magmatic fluids stored within the crust. A major tectonic discontinuity within these units appears to act as a preferential pathway for magma ascent from depth to the surface. By explicitly accounting for crustal anisotropy, this study provides new insights into the structural conditions leading to the emplacement of Mt. Etna, highlighting the interplay between regional tectonics, local stress fields, and magma ascent processes. More broadly, the results underscore the potential of seismic imaging that accounts for anisotropy to investigate the internal architecture of volcanic systems and, from a monitoring perspective, to track the evolution of stress fields and magma migration within the crust.
How to cite: Lo Bue, R., Rappisi, F., Firetto Carlino, M., Giampiccolo, E., Cocina, O., Vanderbeek, B. P., and Faccenda, M.: Anisotropic Seismic Imaging of Mount Etna: Interplay Between Tectonics and Magma Ascent, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-5699, https://doi.org/10.5194/egusphere-egu26-5699, 2026.
Seismic imaging of active volcanic areas is crucial for characterizing subsurface structures that govern fluid circulation, deformation processes, and seismic hazard. In this study, we apply earthquake reflection imaging techniques to passive seismic data recorded at the Campi Flegrei caldera (southern Italy), one of the most active and densely populated volcanic areas in Europe. Building upon a methodology previously validated on synthetic datasets, we assess the capability of passive seismic migration to image crustal-scale reflectors from natural earthquake data.
The proposed approach adapts pre-stack depth Kirchhoff migration (Schneider, 1978) to passive seismic data by exploiting multiple earthquake-generated seismic phases (PP, SS, SP, and PS). To assess the effects of irregular source–receiver geometry, focal mechanism variability, and mixed P–S wavefields, the workflow was first tested on a synthetic dataset generated according to the Campi Flegrei source–station configuration and subsurface model. These tests demonstrate that, despite the lack of controlled acquisition geometry, coherent reflectors can be reliably recovered under realistic noise conditions and velocity uncertainties.
We then applied the validated procedure to real earthquake data recorded during the most recent phase of unrest at Campi Flegrei. From a catalogue of 3,900 high-precision relocated earthquakes (NLL-SSST-WC; Lomax et al., 2022) that occurred between January and September 2025, we constructed five vertical seismic profiles, each 1.5–3.5 km in length and extending to depths of approximately 13 km, by selecting subsets of well-aligned events and stations. Migration was performed using a velocity model derived from available seismic constraints (Zollo et al., 2008) and recent tomographic results (De Landro et al., 2025).
From the migrated sections obtained for the four seismic phases (PP, SP, SS, and PS) along five profiles with different orientations, we applied least-squares (LS) migration (Tarantola, 1984), combined with Shifted Total Variation (SVT) regularization (Zand et al., 2023) and Principal Component Analysis (PCA), to enhance and identify laterally continuous, high-amplitude features interpretable as subsurface interfaces. The results consistently reveal reflectors at depth of approximately 2.7 km, 5.0 km, 6.8 km, 9.5 km, and 11 km.
Our results demonstrate that earthquake-based reflection imaging is a powerful and promising approach for resolving the internal structure of active volcanic systems, even under highly irregular acquisition conditions. This study represents a first step toward the systematic application of passive seismic migration at Campi Flegrei, providing a new framework for imaging subsurface structures that are critical to understanding volcanic dynamics and hazard assessment.
How to cite: Sollai, A., Zollo, A., Nazeri, S., De Landro, G., Zand, T., Xhou, X., and Virieux, J.: Earthquake Reflection Imaging and Migration of the Campi Flegrei Caldera from Passive Seismic Data, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11160, https://doi.org/10.5194/egusphere-egu26-11160, 2026.
Understanding volcanic systems requires the integration of multiple disciplines. Among them, the integration of seismology and petrology is advantageous. In this study, we investigate the crustal and upper-mantle structure beneath Mount Vesuvius using the Receiver Function (RF) technique. The Somma–Vesuvius volcanic complex has experienced both effusive and explosive eruptions over the past ~25 Ma. Because of the dense population surrounding the volcano, it is among the highest-risk volcanoes in Europe, making a detailed imaging of its internal structure essential for risk mitigation.
Receiver Functions are particularly sensitive to seismic velocity contrasts, allowing the identification of major discontinuities and providing constraints on P- and S-wave velocity variations at depth. Building on previous geophysical studies, our work integrates petrological constraints to improve the interpretation of seismic velocity anomalies and their relationship with the magmatic system beneath Vesuvius. This combined approach allows us to link observed seismic features with the physical state of magmatic reservoirs.
We analyzed seismic data from fourteen stations distributed around the volcanic edifice. RFs were computed using a multi-taper deconvolution technique to enhance signal stability. Subsequently, we applied the transdimensional Bayesian inversion method to retrieve probabilistic 1D velocity models and identify the most likely depths of seismic discontinuities. The integration of geophysics with petrological modeling was used to estimate melt fractions associated with the detected low-velocity zones.
Our preliminary results enabled us to correlate the various discontinuities with the stations we deployed around Vesuvius. We have observed at least three distinct layers, separated by discontinuities with marked changes in the Vs. These preliminary results highlight the effectiveness of combining seismic and petrological analyses to constrain the geometry and physical properties of the Vesuvius magmatic system. The identified velocity anomalies shed light on the interaction between crustal and upper-mantle structures and magmatic processes. These findings provide valuable information for ongoing volcanic monitoring and contribute to improving hazard assessment strategies for the Vesuvius area.
How to cite: Ortega-Ramos, V., D'Auria, L., Granja-Bruña, J. L., Cabrera-Pérez, I., Zanon, V., and Pérez, N. M.: Crustal and Upper Mantle Architecture Beneath Vesuvius Revealed by Receiver Functions, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16965, https://doi.org/10.5194/egusphere-egu26-16965, 2026.
One of the objectives of MULTI-MAREX-2 expedition (MSM135) aboard RV MARIA S. MERIAN was to assess potential geohazards associated with shallow-marine explosive volcanism along the South Aegean Volcanic Arc. In this context, we identified two previously undocumented polygenetic shallow-water volcanic systems on the Milos shelf and in the area of the Kos–Nisyros–Yali island group, i.e. in proximity to two major volcanic centers.
Bathymetric data reveal a circular depression approximately 2 km in diameter at a water depth of ~200 m and south of Milos. Seismic reflection data show outward-prograding, upward-concave reflection geometries within an approximately 50 m thick outer ring, which we interpret as volcaniclastic deposits formed by an explosive eruption. The interpretation of this structure as a shallow-water volcano is supported by a ring-shaped positive magnetic anomaly. The volcano-forming eruption may be linked to the formation of the Green Lahar deposits on Milos (T. Cavailhes, pers. comm.). Beneath the main edifice, seismic data image additional outward-prograding sedimentary units, likewise interpreted as volcaniclastic deposits, indicating a polygenetic evolutionary history. Hydroacoustic data reveal gas flares in the water column, documenting ongoing hydrothermal activity that may be responsible for the formation of the mapped sinkholes in the area.
In Kefalos Bay and along the southern coast of Kos, multibeam bathymetry reveals another shallow-water volcano with a crater diameter of approximately 2 km at the seafloor. The southern flanks of this edifice are collapsed, most likely as a result of lateral spreading above mechanically weak volcaniclastic deposits related to the Kos Plateau Tuff eruption at 161 ka. The crater itself is infilled by younger volcaniclastic deposits with a flat top in a water depth of ca. 180 m.
These findings demonstrate that explosive shallow-marine volcanism has occurred at multiple locations along the South Aegean Volcanic Arc more frequently than previously thought, and represents an underestimated geohazard, particularly in coastal regions close to populated areas. This study also demonstrates that seismic data are required to distinguish between monogenetic and polygenetic submarine volcanoes.
How to cite: Hübscher, C., Eisermann, J. O., Gross, F., Kreh, J., Egelhof, C., Friedrich, A., and Hartge, M.: New Explosive Shallow-Marine Volcanoes on the Milos Shelf and near Kos Revealed by Seismic Reflection Data, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-12743, https://doi.org/10.5194/egusphere-egu26-12743, 2026.
The Pausanias volcanic field forms part of the South Aegean Volcanic Arc and is located within the Epidavros Basin west of Methana Island in the Saronic Gulf. Volcanic activity initiated around 450 ka, with the most recent eruption dated to approximately 14 ka. Given the close proximity of the volcanic field to the Greek mainland, eruption recurrence rates and eruptive styles—explosive versus effusive—are critical parameters for regional geohazard assessment. Previous studies were largely based on bathymetric data, unmigrated legacy seismic profiles, and petrochemical analyses of seafloor sediments and rock samples.
Seismic reflection data calibrated with results from IODP Expedition 398 now allow, for the first time, a systematic discrimination between effusive and explosive submarine volcanic products. This approach was applied to the Pausanias volcanic field using new high-resolution multichannel seismic data acquired during the MULTI-MAREX-2 expedition (MSM135) aboard RV MARIA S. MERIAN in spring 2025. MULTI-MAREX is a research initiative of the German Marine Research Alliance (DAM) aimed at improving the assessment of geomarine extreme events and supporting the development of mitigation strategies through a living-lab approach.
Our analysis focuses on five of the six previously identified volcanic edifices. The seismic sections resolve the internal architecture of the volcanic cones, enabling the identification of distinct constructional styles and eruptive phases. The two northern most volcanoes are characterized by complex channelized and ridge-like morphologies composed of multiple lava flows. Their internal reflection patterns are typical of effusive eruptions of low-viscosity lava which explains the ridge-dominated seafloor morphology. Vertically stacked edifices indicate a polygenetic evolutionary history.
In contrast, three of the southern volcanoes exhibit predominantly conical morphologies. Their lower edifices are characterized by outward-prograding, evenly stratified seismic reflections. Core–seismic integration of IODP Expedition 398 sediment data and seismic imagery from the Kolumbo volcanic chain indicates that such reflection patterns are typical of volcaniclastic deposits formed during explosive eruptions. The uppermost parts of the cones, however, display more chaotic, high-amplitude reflections, interpreted as coherent volcanic material such as lava flows or coarse tephra. This stratigraphic transition documents a temporal shift from predominantly explosive activity toward weakly explosive or effusive eruptions during the final constructional stages. The documented occurrence of explosive submarine eruptions significantly increases the geohazard potential of this densely populated region.
How to cite: Egelhof, C., Hübscher, C., Hartge, M., Friedrich, A., Eisermann, J. O., and Gross, F.: Revealing Initial Explosive Eruptions in the Southern Pausanias Volcanic Field (Southern Aegean Volcanic Arc) from Seismic Reflection Data, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-5476, https://doi.org/10.5194/egusphere-egu26-5476, 2026.
This study investigates the process of melt re-injection into a shallow, large magma reservoir after a giant caldera eruption, based on observational evidence. We chose the Kikai Caldera Volcano as our target because it experienced a giant caldera eruption, the Kikai-Akahoya (K-Ah) eruption, 7,300 years ago. High-resolution seismic reflection surveys and analyses of submarine deposits revealed that the uppermost seismic unit is a pyroclastic deposit produced by the K-Ah eruption, with its estimated volume of >71 km³ (Shimizu et al., 2024). The total bulk volume of the K-Ah eruption was then estimated to be 133–183 km³ in DRE (Dense Rock Equivalent), suggesting that it was probably the largest Holocene eruption. To investigate the current state of the magma reservoir beneath the Kikai Caldera Volcano, we conducted a seismic refraction survey using 39 ocean bottom seismometers and an airgun array along a 175 km survey line across the volcano. The results of the 2D P-wave velocity structure revealed a low-velocity anomaly with a reduction rate of over 15% (maximum 22%) directly beneath the volcano, indicating the existence of a large magma reservoir at a shallow depth of 2.5–6 km. This reservoir is approximately trapezoidal in shape, with a width at least equal to that of the inner caldera. The low-velocity anomaly enabled us to estimate the melt fraction to be 3–6%, but it could be limited to 10% at most. Integrating these results with petrological evidence allows us to propose a model of melt re-injection to form a magma reservoir in the same location as the shallow magma reservoir during the giant caldera eruption. The estimated magma depth during the K–Ah eruption period was 3–7 km (Saito et al., 2001, 2003), and the estimated magma depth for the post-caldera central lava dome formed after 3,900 years ago was 2–4 km (Hamada et al., 2023). These depths overlap with the 2.5–6 km depth of the present magma reservoir identified in this study. Furthermore, the central lava dome exceeds 32 km³ in volume and has a different rock composition from that of the K–Ah eruption magma (Tatsumi et al., 2018), suggesting that different melts were reinjected into the magma reservoir at the same location. The model suggests the following scenario: (1) the K–Ah eruption occurred 7,300 years ago, ejecting approximately 160 km³ of material; (2) caldera formation occurred immediately afterwards; (3) after 3,900 years ago, new melt was injected to form a shallow magma reservoir at the same location, with at least 32 km³ of lava reaching the surface to form the central dome; and (4) this is reflected in the current low-velocity anomaly, characterised by increased melting rates in the magma reservoir. This model may demonstrate a common feature of volcanoes that have experienced a giant caldera eruption, and the temporal variation in low-velocity anomalies in the shallow crust is a crucial indicator for eruption prediction.
How to cite: Seama, N., Nagaya, A., Fujie, G., Tanaka, S., Sugioka, H., and Kodaira, S.: Melt re-injection into large magma reservoir at a shallow depth after giant caldera eruption at Kikai Caldera Volcano, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-9371, https://doi.org/10.5194/egusphere-egu26-9371, 2026.
The Eifel volcanic fields represent one of the most prominent expressions of the Cenozoic volcanism in Central Europe. Volcanic activity has occurred episodically since ~40 Ma, with the most recent major eruption at ~13 ka producing highly explosive, gas-rich magmas. The Eifel comprises two Quaternary subfields, each extending over approximately 60×40 km² and hosting numerous volcanic centers. The occurrence of deep low-frequency earthquakes, crustal seismicity, active degassing and continuous regional uplift indicate ongoing magmatic processes. Using data from the recently deployed Eifel Large-N passive-source seismic experiment, which involved ~500 seismic stations of different sensor types, we image the structure of the crust and mantle lithosphere beneath the Eifel volcanic fields using receiver functions. Our results reveal significantly lateral variations in crustal thickness that reflect Variscan orogenic structures subsequently modified by Cenozoic volcanism. The Moho depth decreases from northwest to southeast across the Siegen Thrust and is locally uplifted by up to ~5 km beneath the two Quaternary volcanic fields, reaching depths of ~28 km. The crystalline basement is elevated by ~3 km beneath the East Eifel, indicating substantial crustal exhumation. Beneath the East Eifel, the lithosphere is thinned to ~40 km and spatially correlates with the occurrence of deep low-frequency earthquakes. Together, these observations are consistent with asthenospheric upwelling, which likely facilitates magma generation and fluid migration associated with Eifel volcanism.
How to cite: Yuan, X., Dahm, T., Isken, M., Milkereit, C., Sens-Schönfelder, C., and Zhang, H.: Crustal deformation and deep magma source beneath the Eifel volcanic fields from Large-N seismic experiment, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-12484, https://doi.org/10.5194/egusphere-egu26-12484, 2026.
How structural elements govern magmatic differentiation in the crust remains unclear, particularly in volcanic systems that exhibit substantial lithological diversity. The Taupō Volcanic Zone of New Zealand represents a premier example of such complexity, as it displays pronounced spatial and temporal transitions between andesitic and silicic volcanism. However, a high-resolution seismic framework for its magmatic plumbing system remains elusive, hindering a comprehensive understanding of the mechanisms driving these petrological shifts. Here, we examine crustal velocity structures beneath the Taupō Volcanic Zone by employing a new adjoint-state differential traveltime tomography method and an extensive dataset comprising traveltime picks accumulated over the past 40 years. Our final velocity model reveals the fundamental role of an intact and impermeable upper crustal lid in controlling the vertical distribution and maturation of magma in the crust. The mechanical state of this lid effectively dictates the storage levels of less-evolved melts, whereas its structural degradation due to extension and thermal erosion facilitates magma ascent and the subsequent development of more differentiated, shallow reservoirs. These findings provide a plausible framework for understanding the transition between different magmatic styles and offer new insights into the mechanisms driving the spatial and temporal evolution of arc and rift systems globally.
How to cite: Wu, S.: Crustal magma plumbing system beneath the Taupō Volcanic Zone of New Zealand, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17891, https://doi.org/10.5194/egusphere-egu26-17891, 2026.
The dynamic processes of magma replenishment and eruption of an active volcano are key to understanding the magma plumbing system and the mechanism of magma movement. Myriad studies focus on the long-term processes of melt accumulation and migration before the eruption, the transient and massive outflow and influx of magma during the eruption, and the associated mixing processes of melt and crystal mush are poorly resolved so far. Capturing the transient magma movement at depth is an important yet challenging task, for it can provide direct evidence of such a magmatic process. Shear-wave velocity is sensitive to the melt content and melt connectivity, therefore the velocity variation is a good proxy for detecting the interaction between fresh melts with the existing crystal mush.
Axial Seamount (AS), located in the intersection of the Juan de Fuca ridge and the Cobb hotspot, is an active submarine volcano and has erupted in 1998, 2011, and 2015 in the past three decades. Significant effort has been made to use the ambient noise for continuous monitoring of magmatism at Axial Seamount. Unfortunately, none of the results so far can capture the change inside the reservoir during the eruption, either due to the lack of data or the lack of spatial sensitivity to the magma reservoir.
Since 2014, the Ocean Observatory Institute (OOI) has running 7 cabled permanent ocean bottom seismometers around the caldera and a satellite seismometer approximately 25 km to the southeast, providing a great chance to resolve the magma movement inside the magma reservoir during the 2015 eruption. In this study, to investigate the magma movement inside the reservoir during the eruption, we calculated the empirical Green’s function along the long paths between satellite station AXBA1 and the caldera array and successfully extracted Rayleigh waves at periods of 4-6 s (0.16 – 0.25 Hz), which are most sensitive to the velocity in the depth range of the major magma reservoir (MMR) from 1.5-2.5 km. Given that a considerable portion of the paths lies outside the caldera region, the predominant velocity variation originating from the caldera area could be as large as 4%. The velocity decrease, which is significant enough (> 2sigma) from the background seasonal variation, occurred in a consequential manner from the central to the southwestern magma reservoir. We propose that the rapid influx of melt after the 2015 eruption caused a strong mixing of the fresh melt with the crystal mush in a time period of a few months, presenting a very different way of replenishment than the long-term trend.
How to cite: Ruan, Y.: Seismic observation of magma mixing inside the magma reservoir after the 2015 eruption of Axial Seamount, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16018, https://doi.org/10.5194/egusphere-egu26-16018, 2026.
Plume-lithosphere interaction (PLI) is a fundamental geodynamic process linking deep mantle dynamics to surface volcanism and lithospheric evolution. The lithosphere serves as an archive of past modifications, where distinct tectonic settings undergo unique deformation histories that are manifested as variations in thickness and seismic velocity. To characterize the nature and variability of different PLI modes, we conduct a comparative study across three tectonic settings: Iceland (ridge-centered hotspot), Hawaii (oceanic intraplate hotspot), and Hainan Island (continental margin upwelling). Utilizing Ps and Sp receiver functions, we image crustal and upper-mantle discontinuities in each tectonic setting. By integrating Vp/Vs ratios with seismic velocity anomalies, we further constrain the distribution of potential melt within the lithosphere. This study tests the hypothesis that contrasting lithospheric structures arise from different PLI modes, which in turn regulate the ascent, emplacement, and storage of magma. This study aims to provide seismological constraints on the evolution of PLI, potentially offering new insights into the genesis of surface volcanism. The detailed results and ongoing progress will be presented at the meeting.
How to cite: Zhang, Z., Deng, Y., and Zhu, S.: Plume-Lithosphere Interaction Across Different Hotspots: A Comparative Study of Iceland, Hawaii, and Hainan Island, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-15569, https://doi.org/10.5194/egusphere-egu26-15569, 2026.
In this study, we reprocessed and interpreted seven vintage deep-seismic profiles acquired offshore Campi Flegrei by OGS in the 1970s (Finetti and Morelli, 1974), whose potential could not be fully exploited at the time due to technological limitations. The reprocessing of vintage seismic reflection data represents a valuable scientific opportunity, particularly in geologically complex settings such as the Campi Flegrei area. Despite the complexity of the subsurface, deep geophysical exploration in the area has thus far relied mainly on potential-field methods and passive-source seismic tomography, both of which lack the resolution required to unravel the subsurface architecture at depth. Our main goal was to enhance the signal-to-noise ratio and improve depth imaging of these offset-limited datasets using the Common Reflection Surface (CRS; Zhang et al., 2001; Deidda, 2012) method alongside pre-stack migration techniques (Yilmaz, 2001).
The CRS technique improves subsurface imaging by increasing the signal-to-noise ratio, reflector continuity, and the visibility of dipping events. Unlike traditional common-depth-point (CDP) stacking, it accounts for lateral heterogeneities and dipping structures by using additional kinematic parameters and integrating information from adjacent CDP gathers (Deidda, 2012). By summing amplitudes along reflector segments, CRS produces higher-quality common-offset gathers suitable for the application of pre-stack migration methods (Garabito et al., 2012), particularly when the aim is to improve overall depth imaging rather than resolve subtle details. This is especially relevant because pre-stack depth migration (PSDM; Yilmaz, 2001) yields more reliable seismic images in volcanic environments, where strong vertical and lateral velocity variations and structurally complex subsurface conditions make the assumptions underlying post-stack migration unrealistic. On the other hand, PSDM requires robust and well-constrained velocity models.
The initial velocity model for PSDM was subsequently refined using the iterative Deregowski Loop approach (Deregowski, 1985, 1990). This method relies on common-offset binning of pre-stack data to identify velocity errors and suppress noise and unwanted lateral reflections, followed by Kirchhoff depth migration. Starting from an initial velocity model, refinement is carried out through the analysis of Common Image Gathers (CIGs), where residual moveout (RMO) is evaluated using semblance functions.
The combined use of CRS and PSDM in this work proved particularly effective in improving the imaging quality of the vintage profiles. This approach enabled the construction of a consistent velocity model and the effective use of seismic data for a better understanding of the geological and structural framework of the study area. The integration of CRS and PSDM also ensured coherent results and good comparability among the different seismic lines, providing a robust basis for geological interpretation. The reprocessed data support a reconstruction of the subsurface at considerable depth, allowing the identification of fault structures, volcanic edifices, explosive eruptive sequences, and preferential gas-leakage pathways. Reliable seismic imaging from reflection-seismic exploration data is essential to avoid interpretative ambiguities in the Campi Flegrei caldera, a highly complex volcanic system influenced by rising magmatic fluids, pervasive faulting, and intrusive bodies buried beneath younger volcaniclastic deposits.
How to cite: Ferrara, G., Bruno, P. P., and Di Vito, M. A.: Reprocessing and interpretation of vintage seisimc reflection profiles in the offshore Campi Flegrei caldera, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-485, https://doi.org/10.5194/egusphere-egu26-485, 2026.
The Ninety East Ridge (NER) is a prominent linear intraplate volcanic ridge in the eastern Indian Ocean. Seismicity has long been recognized to occur along it in the context of the Indian Ocean intraplate deformation zone. At the latitude of northern Sumatra, the NER hosted moment release during the great Mw 8.6 Wharton Basin earthquake rupture, and several aftershocks with dominantly strike-slip mechanisms. However, its crustal architecture in that area, especially the extent of active faults at depth, is poorly known owing to a scarcity of active-source seismic data. In this study, we utilize a two-dimensional marine multichannel seismic (MCS) dataset acquired by the R/V Marion Dufresne (MIRAGE experiment) in the region of the 2012 rupture zone over northern NER (1.5-3N). An airgun source of 2750 in3 volume was fired at 50 m interval, and a streamer equipped with 720 hydrophone groups spaced at 6.25 m interval was used to record seismic data. We processed the MCS data using a conventional marine seismic processing workflow using successively a band-pass filter, an FK filter for coherent linear noise attenuation, several passes of velocity analyses, normal move-out correction, stacking, and finally post-stack time migration. We focus here on a 176-km long profile oriented N-S direction, along which the water depth varies between ~ 2 km in the north and 3 km in the south. The preliminary interpretation of the migrated image reveals several structural features indicating active deformation and segmentation along the profile. We find a veneer (200-300 m thick) of pelagic sediments underlain by 300-500 m thick volcanoclastic deposits over the acoustic basement. In the crust below the top of basement, we observed a low-frequency event, which could be due to the Layer 2A/2B boundary. The seafloor and sediments show signs of active deformation, possibly associated with NW-SE trending fault planes of strike-slip earthquakes. The presence of a couple of negative flower structures further supports strike-slip deformation on the NER. In this presentation, we will present results linking seismic reflection images with drilling results (DSDP Hole 216) and earthquakes on the NER to shed light on active deformation along the NER in this region.
How to cite: Kumar, P., Ghosal, D., Singh, S., Carton, H., and Hananto, N.: Investigating Northern Ninety East Ridge (NER) using high-resolution Multichannel Seismic Reflection Data, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-19198, https://doi.org/10.5194/egusphere-egu26-19198, 2026.
Intraplate off-axis volcanism west of Iceland forms a volcanic province whose origin remains largely unexplored, despite extensive research on the nearby Reykjanes Ridge and onshore Iceland. Integrating 2950 km of multi-channel reflection seismic data with vertical gravity gradients, this study investigates the Vesturdjúp Basin (1000 – 2100 m water depth), where 43 volcanic edifices are preserved in the reflection seismic data. In the northern part of the basin, volcanic cones align along two perpendicular chains and a ridge-parallel lineament, while the southern part of the basin exhibits more dispersed volcanism.
Seismic facies analysis indicates a multi-stage magmatic evolution, shifting from early effusive flows to an explosive cone-building phase, before returning to effusive activity. Deep-water explosive volcanism is indicated by diatreme-like sub-surface geometries and outward-prograding flank reflections, interpreted as volcaniclastic aprons. Detailed seismostratigraphic reconstruction of representative edifices shows that construction progressed through repeated cycles of crater excavation and infill, accompanied by small-scale mass-transport deposits along the by oversteepened flanks.
Stratigraphic correlation suggests that volcanism was modulated by a pulsed magmatic regime. The timing of eruptive activity and intervening quiescence likely correlates with fluctuations in Iceland plume flux and regional tectonic reconfigurations. The spatial distribution of volcanic centres reflects the reactivation of inherited lithospheric weaknesses and rift-related discontinuities. These structural corridors may have provided pathways for plume-derived magma to ascend through the cooling off-axis lithosphere. Our results demonstrate how high-resolution seismic imaging can help to reconstruct the formation history of off-axis volcanism where structural inheritance and transient plume pulses overlap.
How to cite: Schmidt, M. C., Hübscher, C., Preine, J., Ford, J., and Pałgan, D.: Reconstructing the Magmatic and Volcanic Evolution of the Vesturdjúp Basin (Offshore Iceland) Using Reflection Seismic Imagery, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-5726, https://doi.org/10.5194/egusphere-egu26-5726, 2026.
Explosive caldera-forming eruptions discharge large volumes of silicic magma and pose one of the greatest hazards to human population. Effective risk evaluation depends on detailed records of past events, however, accurately quantifying the volume of ejected material and therefore the magnitude of eruptions remains a challenge. This is particularly the case in marine settings, where much of the eruptive record is obscured or poorly preserved. Santorini in the Aegean Sea is one of the world’s most prominent calderas and the result of at least four caldera-forming eruptions. The 1600 BCE Minoan eruption represents the most recent caldera-forming event, and is among the most extensively studied eruptions worldwide. While recent marine geological and geophysical analyses enabled reconstruction of the 1600 BCE eruption volume and temporal evolution in greater detail, little is known about its predecessor, the caldera-forming Cape Riva eruption, which occurred at ~22 ka. Recent investigations of marine sediment cores suggest that the Cape Riva eruption produced a tephra volume comparable to or exceeding that of the Minoan eruption. In this study, we integrate for the first time high-resolution 2D and 3D seismic reflection data with sedimentological constraints from marine sediment cores to assess the volume of the Cape Riva eruption with high precision and compare it to the Minoan eruption. Our results reveal that the Cape Riva eruption emplaced, at least in near offshore areas, substantially thicker ignimbrite deposits than the Minoan eruption. These results imply that the Cape Riva eruption may have been larger than previously recognized and that previous offshore ignimbrite volumes attributed to the Minoan eruption may have been overestimated. Our study emphasizes the challenges of reconstructing large explosive eruptions in submarine environments, and highlights the importance of integrating high-resolution seismic imaging with marine sedimentological analyses to improve volume estimates.
How to cite: Blanch Jover, M., Karstens, J., Kutterolf, S., van der Bilt, W. G. M., Arneke, A., Kopp, H., Berndt, C., Crutchley, G. J., Preine, J., and Nomikou, P.: Reassessing the volume of the Cape Riva eruption (Santorini) using integrated seismic imaging and marine sediment cores, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-9240, https://doi.org/10.5194/egusphere-egu26-9240, 2026.
Imaging the subsurface plumbing systems of active volcanoes is essential for understanding magmatic and fluid transport processes and for improving eruption forecasting. However, seismic imaging in volcanic environments is intrinsically challenging due to strong heterogeneities, intense wave scattering, and rapidly evolving geological conditions. These difficulties are often compounded by complex topography and logistical constraints, which limit the deployment of dense seismic networks and reduce the effectiveness of conventional source-based imaging approaches.
In this context, passive techniques exploiting incoherent seismic wavefields, particularly Ambient Noise Tomography (ANT), have become central tools for volcanic imaging. Since its introduction, ANT has enabled the retrieval of inter-station Green’s functions from ambient noise cross-correlations, allowing imaging of subsurface structures without active sources. While early applications focused mainly on shear-wave velocity (Vs) models, recent developments have demonstrated the potential of ambient noise data to constrain additional physical properties, including three-dimensional seismic attenuation.
Building on these advances, a matrix-based imaging framework has recently been introduced to seismology. Matrix Imaging exploits the array response matrix constructed from impulse responses between all receiver pairs, which can be obtained from ambient noise correlations. This approach allows the coherent extraction of scattered and reflected body-wave energy embedded in noise records, without requiring a detailed a priori velocity model, making it particularly well suited for sparse arrays in strongly heterogeneous volcanic settings.
We applied Matrix Imaging to ambient seismic noise data recorded at Vulcano Island (Italy), a volcano characterized by recurrent unrest episodes but no eruptions since 1888–1890. Previous studies suggest a deep magma reservoir at ~20 km depth and a possible shallow storage zone at ~2 km, overlain by an active hydrothermal system. Interpretations of recent unrest, including the 2021 episode, remain debated. This study aims to provide new constraints on the shallow structure of Vulcano Island and to assess the potential of matrix-based methods for high-resolution passive imaging of active volcanic systems.
How to cite: Cabrera Pérez, I., Stumpp, D., Burtin, A., Sfalcin, J., and Lupi, M.: High-Resolution Seismic Imaging of Vulcano Island Based on Matrix Imaging, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-3857, https://doi.org/10.5194/egusphere-egu26-3857, 2026.
The growth of the Tibetan Plateau is resulted from the ongoing collision between the Indian and Eurasian plates since the Cenozoic. The western Yunnan region is located on the southeastern margin of the Tibetan Plateau and represents an important tectonic transition zone, characterized by outward material flow from the Tibetan Plateau, interactions among multiple tectonic blocks, and complex crust-mantle coupling processes. The Tengchong Volcanic Field (TCV), situated in western Yunnan, is the largest active volcanic field in China and is characterized by intense hydrothermal activity and frequent seismicity. Multiple geophysical observations indicate that low seismic velocities and low electrical resistivity at different depths in the crust beneath the TCV, which are commonly interpreted as the existence of magma chambers. However, how mantle-derived materials are transported upward and continuously supply the crustal magma system, as well as the specific pathways and dynamic mechanisms involved, remain poorly understood. Therefore, the crustal and uppermost mantle structure of the Tengchong magma system warrants further study.
In this study, we develop a new joint inversion method that combines body-wave and surface-wave data. Using the chain rule, the sensitivity kernels of S-wave travel times and surface-wave dispersion with respect to Vs are transformed into sensitivity kernels for Vp and Vp/Vs, and S-P travel-time data are incorporated to further enhance constraints on the Vp/Vs structure. In addition, the variation of information constraint is introduced to strengthen the intrinsic coupling between the Vp and Vp/Vs models, and the objective function is efficiently solved using the L-BFGS optimization algorithm. Based on this approach, we obtain high-resolution three-dimensional Vp, Vs, and Vp/Vs models beneath the TCV. The results reveal a spatially continuous low-Vs and high-Vp/Vs anomaly in the lower crust beneath the TCV, which extends upward from the lower crust and closely corresponds to the shallow seismicity and the location of the volcanic centers, indicating the presence of partially molten or fluid-rich materials. An overlying high-velocity layer above the lower-crustal low-velocity anomaly reflects relatively dense and mechanically strong middle-crustal material, which exerts mechanical sealing and lateral confinement on the underlying partially molten or fluid-rich zone. This structure effectively controls the ascent pathways of magma and the spatial distribution of shallow seismicity. Our results suggest that the Tengchong volcanic system is not controlled by an isolated shallow magma chamber but is instead governed by a vertically connected magma system dominated by a deep-seated weak zone or a melt-fluid-rich conduit.
How to cite: Huang, Y., Zhang, H., Hao, J., Liu, Y., and Moorkamp, M.: A Vertically Connected Melt-Fluid-Rich Magma System Beneath the Tengchong Volcanic Field, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-15618, https://doi.org/10.5194/egusphere-egu26-15618, 2026.
We present a probabilistic anisotropic P-wave tomographic study of the Kivu segment of the western East African Rift, incorporating local seismicity recorded by the Kivu Seismic Network. Using a Bayesian inversion approach, we map both isotropic velocity variations and directional anisotropy, providing robust estimates of uncertainties. Our results reveal broad low-velocity zones (~–2%) likely associated with magma-rich regions, and fast domains corresponding to rigid crustal blocks. South of the Virunga Volcanic Province (VVP), fast anisotropic planes are predominantly rift-perpendicular, while rift-parallel orientations dominate in distal regions, especially in the easternmost sector. Numerical modelling indicates that volcanic and topographic loading can explain rift-perpendicular anisotropy near the VVP, but not the patterns observed farther from volcanic edifices, suggesting a combined influence of regional extension, magmatic activity, and long-lived structural inheritance. These findings provide new insights into the interplay between crustal structure, tectonic stress, and magmatism, with implications for rift evolution and regional seismic and volcanic hazard assessment.
How to cite: Oth, A., Rappisi, F., Barrière, J., d'Oreye, N., Smittarello, D., Faccenda, M., Del Piccolo, G., and Vanderbeek, B. P.: Mapping Crustal Structure and Stress in the Kivu Rift from Bayesian Anisotropic Tomography, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-6897, https://doi.org/10.5194/egusphere-egu26-6897, 2026.
The deployment of dense seismic arrays on volcanoes has increased significantly over the past decades, enabling more precise monitoring of volcanic activity. While short-period sensors are commonly used, Distributed Acoustic Sensing (DAS) represents a promising complementary technology, providing high spatial resolution and remote location of the interrogator. Accurate monitoring requires a robust understanding of seismic wave propagation, particularly within the shallow subsurface beneath the sensors. On volcanic edifices, the distribution of eruptive deposits along the flanks can be highly heterogeneous, leading to strong lateral variations in physical properties that can significantly aFect seismic records.
In this study, we use ambient noise cross-correlation to characterize the subsurface velocity structure beneath a 3 km long DAS cable deployed on Stromboli volcano, Italy. We analyse two months of continuous strain rate data acquired on this persistently active volcano, which allows the application of a passive approach. Empirical Green’s Functions (EGFs) are retrieved using Phase Cross-Correlation and times-scale Phase Weighted Stack methods. They are validated through comparison with EGFs obtained from collocated short-period seismic sensors. Local phase and group velocities are then computed along the optical fiber and inverted to determine the 2D S-wave velocity profile. We clearly identify 2 distinct regions along the profile which are correlated with changes of local topography, eruptive activity and deposits.
How to cite: Hebrard, L., Stutzmann, E., Metaxian, J.-P., Biagioli, F., Lacanna, G., Bonilla, F., Schimmel, M., Bernard, P., and Ripepe, M.: Ambient Noise Cross-Correlations along Distributed Acoustic Sensing (DAS) for Imaging the Subsurface at Stromboli Volcano , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-6577, https://doi.org/10.5194/egusphere-egu26-6577, 2026.
Unraveling the nature (physical state) of magma reservoirs beneath active volcanoes is essential to understand their eruption potential. Magma can be in a pure melt state and hence it is more likely to erupt if supplied by fresh melt from below, or in a mush state that is less likely to erupt. However, imaging magma reservoirs on land and deciphering their physical properties is inherently difficult, but the submarine environment offers more favorable conditions and therefore magma reservoirs have been commonly imaged beneath fast and intermediate spreading centers. Moreover, when several collocated high-quality seismic datasets are available at different times, time-lapse seismic analysis, commonly used in industry, could be applied to study the evolution of the reservoir through multiple eruptions cycles.
The Axial Volcano is a large submarine volcano at the intersection of the Juan de Fuca Ridge and Cobb hotspot that hosts many hydrothermal vent fields and has erupted three times (1998, 2011 and 2015) in recent years. The volcano was the site of a seismic reflection survey in 2002 and some lines were reshot after the 2011 and 2015 eruptions, respectively in 2012 and in 2019. In this study, we focus on one NW-SE oriented profile and apply time-lapse techniques to investigate changes in the magma reservoir before and after the 2011 and 2015 eruptions. Time-lapse signals could be due to the change in depth of the top of magma reservoir and/or a change in the state (melt versus mush) of the magma. The three data vintages were first processed to remove the effect of the data acquisition footprint, which included deghosting, wavelet shaping, amplitude balancing, and time alignment. Dynamic time warping was applied to measure time shifts on stacked images, and amplitude energy changes (reflecting impedance contrast variations) were subsequently computed. In addition, absolute reflection coefficients were calculated to obtain indications on melt fraction evolution through time.
Preliminary analysis of time-lapse signals reveals inflation and deflation of the magma lens before and after eruptions on the scale of a few meters up to ~15 m. In comparison with 2002, one year after the 2011 eruption, the magma lens has inflated in its portion southeast of the caldera and deflated beneath the 2011 lava flow inside the caldera. Interestingly, the melt percentage has decreased everywhere. Then 4 years after the 2015 eruption, in comparison with 2012, the portion of the magma lens beneath the 2011 lava flow inside the caldera and southeast of the caldera has undergone deflation, whereas the portion beneath the 2015 lava flow inside the caldera has continued to inflate slightly, with melt fraction increasing in both regions. That we observe inflation associated with a decrease in melt fraction (and conversely) suggests that the vertical uplift of the top of the magma reservoir occurs with a temporal lag relative to melt migration along the lithosphere-asthenosphere boundary into the shallow part of the reservoir.
In this contribution, we will present the details of our time-lapse methodology and insights gained about magma dynamics at Axial Volcano using our methodology.
How to cite: Zhao, Y., Carton, H., Singh, S., Ardalan, M., and kent, G.: Dynamics of magma reservoir before and after volcanic eruptions at the Axial Volcano in the Eastern Pacific using time-lapse seismic imaging method, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13399, https://doi.org/10.5194/egusphere-egu26-13399, 2026.
The preferential alignment of eruptive fissures, dikes, sills, and (fluid-filled) microcracks with the local stress field - typical for the crust beneath volcanoes - causes the velocity of seismic waves to vary with propagation direction with respect to these aligned fractures (seismic anisotropy). Investigations based on shear wave splitting (Savage et al., 2010; Nardone et al., 2020; among others) and anisotropic P-wave tomography (Lo Bue et al., 2024; Del Piccolo et al., 2025) have demonstrated the presence of strong crustal anisotropy beneath Mt. Etna and other volcanic systems. However, the assumption of an isotropic crust is still common in seismic tomography, while methods for anisotropic tomography are still scarce and mostly limited to P-waves.
The well-established sensitivity of S-waves to anisotropy (shear wave splitting) suggests that extending anisotropic tomography methods to S-wave data may provide valuable new constraints on the anisotropic structure of volcanoes. Moreover, comparison of results of previous synthetic P- and S-wave tomography studies (Vanderbeek and Faccenda, 2021; Vanderbeek et al., 2023) indicates that S-wave data may be better capable of constraining shallow anisotropic heterogeneity. Additionally, Vp/Vs anomalies — often interpreted in terms of rock and fluid properties —exhibit a particularly strong directional dependence (Wang et al., 2012) in anisotropic media. This stresses the importance of coupling P- and S-wave data in anisotropic tomographic inversions.
We aim to show preliminary results of joint P- and S-wave anisotropic tomography, providing new constraints on the stress state and rock fluid properties of the crust beneath Mt. Etna. The method is an extension of the probabilistic anisotropic P-wave tomography method of Del Piccolo et al. (2025). Transdimensional Bayesian Monte Carlo sampling is applied to allow for robust uncertainty estimation, without the need for the subjective choice of damping and smoothing parameters that often limits more common deterministic tomography approaches.
How to cite: van Helden, K., Vanderbeek, B., Del Piccolo, G., Faccenda, M., Lo Bue, R., Giampiccolo, E., Cocina, O., and Firetto Carlino, M.: New constraints on Vp/Vs ratios and stress distribution at Etna volcano from anisotropic joint P- and S-wave tomography, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7944, https://doi.org/10.5194/egusphere-egu26-7944, 2026.
How to cite: Floridia, S., Vinciguerra, S. C. G., De Siena, L., and Adinolfi, G. M.: Ambient noise surface wave tomography of Mt. Etna volcano structure during 2020-2021, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-8151, https://doi.org/10.5194/egusphere-egu26-8151, 2026.
The Campi Flegrei caldera is currently experiencing significant ground deformation and bradyseismic activity, yet the subsurface processes driving this unrest remain debated. Competing interpretations invoke magmatic intrusion, hydrothermal circulation, or regional tectonic stress, with no consensus on the role of magma at depth.
Here, we present results from a new probabilistic high-resolution seismic tomography of the Campi Flegrei caldera, imaging both isotropic velocity structure and seismic anisotropy using P-wave arrival times from a recently published, machine-learning–derived seismic catalog (Tan et al., 2025). The model reveals a pronounced low-velocity volume extending from shallow levels down to approximately 7 km depth. Within this region, anisotropy patterns are characterized by vertically oriented fast axes and predominantly horizontal slow axes, consistent with aligned vertical cracks or dike-like structures. The magnitude and spatial coherence of the inferred anisotropy, together with the observed low velocities, are difficult to reconcile with purely hydrothermal or tectonic processes. Instead, they suggest a stress regime compatible with upward pressurization from depth, potentially associated with magmatic intrusion. These interpretations are further supported by numerical modeling that tests alternative source configurations and reproduces the observed anisotropy orientations only when deep magmatic pressurization is included. While alternative mechanisms cannot be fully excluded, our results indicate that magma may play an active role in driving the ongoing deformation of the Campi Flegrei caldera.
These findings provide new constraints on the physical processes underlying caldera unrest and have important implications for hazard assessment in one of the most densely populated volcanic regions in the world.
Tan, X., Tramelli, A., Gammaldi, S., Beroza, G. C., Ellsworth, W. L., & Marzocchi, W. (2025). A clearer view of the current phase of unrest at Campi Flegrei caldera. Science, 390(6768), 70-75.
How to cite: Rappisi, F., Oth, A., Barrière, J., Faccenda, M., Del Piccolo, G., and Lo Bue, R.: Does Deep Magma Power the Campi Flegrei Caldera? Evidence from Seismic Tomography and Anisotropy, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10379, https://doi.org/10.5194/egusphere-egu26-10379, 2026.
Campi Flegrei caldera (Naples, Italy) is one of the most active volcanic systems worldwide, continuously monitored by the Istituto Nazionale di Geofisica e Vulcanologia - Osservatorio Vesuviano (INGV-OV). Intense hydrothermal activity, recurrent seismicity and significant episodes of ground uplift (bradyseism) peaking at the caldera centre over the last decades have been related to the dynamics of a complex magmatic-hydrothermal system. Previous studies indicate active fluid migration through the Solfatara-Pisciarelli hydrothermal system, as well as strong small-scale heterogeneities and gas accumulation and release in this area. In this work, we produced a time-dependent Rayleigh-wave tomography model of Campi Flegrei caldera using the Python Package SeisLib. We applied the method to three years of ambient noise data (from January 2022 to December 2024). This period corresponds to the most significant seismic unrest of the last 40 years, with a total of 37 seismic events with duration magnitude Md≥3.0 and a maximum magnitude of Md=4.4 on May 20, 2024. We used records of 18 seismic stations of the INGV-OV network, 17 from the IV network and 1 (CFB3) from the Medusa network. We processed the continuous seismic records using a standard ambient-noise processing workflow, including the removal of transient seismic swarms and band-pass filtering. Data were then resampled and cross-correlated for all available station pairs, knowing that cross-correlation of seismic ambient noise can be related to the surface-wave Green function between two points of observation. From these, we extracted Rayleigh-wave dispersion curves in order to produce phase-velocity maps at 0.25 Hz, 0.50 Hz, 0.75 Hz, 1.0 Hz, 1.25 Hz and 1.50 Hz. Here, we focused on the three highest frequencies (1.0 Hz, 1.25 Hz and 1.50 Hz), which provide the best resolution in the shallowest portion of the caldera. Inversions for Rayleigh-wave phase velocities reveal high-velocity anomalies in the Solfatara-Pisciarelli area, with values ∼100 m/s above average velocities, and sensitivity extending to a few hundred meters of depth. These velocities are consistent with the presence, below the Solfatara-Pisciarelli region, of a shallow hydrothermal system comprising an aquifer and shallow faults. The spatial distribution of the anomalies is also qualitatively consistent with geophysical models indicating the presence of a clay cap atop a highly resistive plume, constrained by faults, that feeds the fumaroles on the surface. High-frequency Rayleigh-wave phase velocities, obtained from the inversion, are also consistent with the presence of an elongated shallow zone of high rigidity. This transfer structure, formed by lateral stress accumulation in the crust, crosses the resistive plume that stores steam and gas beneath the Solfatara-Pisciarelli system. The results are also consistent with the interpretation that shallow faults in the Solfatara-Pisciarelli area act as preferential conduits for ascending gases and hydrothermal fluids.
How to cite: Di Dato, C., Tramelli, A., and De Siena, L.: Ambient Noise Tomography of Campi Flegrei caldera (Naples, Italy): High Frequency Phase-Velocity Anomalies beneath the Solfatara-Pisciarelli Hydrothermal System, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13821, https://doi.org/10.5194/egusphere-egu26-13821, 2026.
