The Fucino Basin, the largest tectonic basin within the Central Apennines orogen, is bounded by normal faults that have controlled the deposition of over 1 km of Pliocene-Quaternary continental deposits above a Messinian substratum. Conflicting interpretations from legacy seismic profiles have hindered a full understanding of the basin's stratigraphy, age, evolution, and fault systems, creating uncertainties for tectonic reconstructions, seismic response analysis and hazard assessment. To resolve these uncertainties, we acquired new high-resolution datasets through three complementary active-passive seismic surveys. These include seismic reflection profiles covering similar to 10 km, a nodal ambient noise campaign deploying 258 short-period nodes over 16 km2, preceded by two pilot array tests, and finally a basin-wide ambient noise survey comprising 1-hour recordings at 42 sites. Our analysis focused on the San Benedetto and Trasacco Faults-responsible for the 1915, M7.1, Marsica earthquake-and the main depocenter (the Bacinetto) associated with the San Benedetto Fault. This paper presents experimental setup, recorded data, and initial findings that provide new insights into basin stratigraphy, fault geometry, and spatial distribution of the fundamental resonance frequency (f0). The seismic reflection data show excellent imaging quality, resolution, and penetration exceeding 1 km. The Bacinetto hosts up to 850-900 m of continuous lacustrine succession and lower fluvio-lacustrine deposits that record sustained syn-sedimentary slip along the San Benedetto Fault from the Late Pliocene to Recent times. No evidence is found for significant synthetic or antithetic faulting beneath the depocenter, contradicting earlier structural models. The intra-basin Trasacco Fault forms a clear basement step and localized sediment thickening that tapers northwestward f0 varies from 1 to 2 Hz near the basin margins to similar to 0.2 Hz in the Bacinetto, reflecting progressive sediment thickening, whereas it varies abruptly across fault zones. f0 estimates from nodal and station data show good consistency.

Hydrothermal alteration exerts strong control on shallow permeability and degassing dynamics in geothermal systems. Here, we investigate how soil alteration influences near-surface gas flow by combining in situ petrophysical measurements with horizontal and vertical subsurface gas-concentration profiles at the Rotokawa geothermal field, New Zealand. These data are compared against unoccupied aerial system (UAS) thermal surveys of collapse structures across the field. Soil permeability at Rotokawa ranges from 8.7 × 10–14 to > 6.5 × 10–13 m2, highlighting strong meter- to decimeter-scale heterogeneity in shallow soil properties. Pumice-rich horizons are the main conduits for CO2 and CH4 flow, whereas clay-rich horizons locally act as semiconfining layers that promote CO2 accumulation and lateral diversion (leading to concentrations of > 4 × 104 ppm). Since CO2 does not condense under near-surface conditions, the clay layers promote horizontal flow along permeable beds until gas encounters a high-permeability escape route or collapse-related discontinuity. Collapse structures locally disrupt and reorganize flow by acting as conduits or sinks that focus, capture, or redistribute gases near their margins. The gas profiles reveal patterns consistent with a shallow gas–steam decoupling zone in which steam condensation may contribute to sealing processes, as previously observed in steam-heated geothermal systems worldwide. These coupled effects of soil type and structural and alteration controls explain the spatial heterogeneity of surficial degassing at Rotokawa and provide a framework for interpreting evolving degassing patterns in similar steam-heated geothermal systems. In the context of the reported decrease in diffuse CO2 emissions at Rotokawa, progressive shallow sealing and gas refocusing may have contributed to apparent changes in emission patterns, alongside reservoir processes, recharge variability, environmental effects, and methodological uncertainty.

Abstract. Active volcanic islands, such as Stromboli in southern Italy, are sites where tsunamis generated by volcanic activity could be frequent and potentially destructive. Stromboli Island has experienced several landslides over the past decades, some of which have generated destructive tsunamis. This paper is part of a broader project aimed at developing a Probabilistic Tsunami Hazard assessment (PTHA) for Stromboli. We present here a review of historical tsunamis sourced from Stromboli, their correlation with explosive activity, and the results of an expert elicitation on tsunamigenic landslides. In our review of historical tsunamis, we identified 16 events from 1879 to 2024, grouped into three classes based on the degree of inundation observed in the village of Stromboli, ranging from few ten to few hundred of meters inundation distances, the latter comparable to the widely documented December 2002 tsunami event. Four historical tsunamis (in 1879, 1921, 1924, and 1959 CE) have been critically discussed for the first time. Over the past 150 years, ~69 % = 11/16 of the catalogued tsunamis, with 90 % confidence [45 %, 87 %], were associated with paroxysms, while only ~27 % of historical paroxysms were associated with catalogued tsunamis, confidence [16 %, 40 %]. Similar conditional probabilities and uncertainty intervals were estimated from 1916 to 2025, excluding the tsunamis without significant inundation. The expert elicitation was divided in three parts. Part I provided estimates and uncertainty quantification of the number of tsunamigenic landslides at Stromboli (with volumes ≥ 1 × 106 m3) in the past and of those expected in the next 50 years. Part II focused on the probabilities of different triggering mechanisms in the next 50 years. Part III quantified the probabilities of different tsunamigenic landslides (volume and positions) along the Sciara del Fuoco in the next 50 years. Results of the expert elicitation indicate that return periods of tsunamigenic landslides at Stromboli in the next 50 years have median values in the order of 10–12 years (with uncertainty from 3 to 50 years), and a median probability of their occurrence along the Sciara del Fuoco of either 82 or 86 % (depending on the weighting scheme used in the elicitation). Results of part III indicate slightly higher median probabilities for landslides occurring at elevation 300 to 700 m a.s.l. along the Sciara del Fuoco with volumes 1–5 × 106 m3 as compared to other elevation and volume ranges.

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

The 2020 Mw 6.4 Petrinja earthquake in central Croatia is one of the European strongest continental earthquakes in recent decades. This event shed light on the poorly investigated Petrinja-Pokupsko Fault (PPKF) zone, a right-lateral fault system accommodating a fraction of the shortening between the Adria and European plates. Through field observations and high-resolution Lidar-derived digital elevation models of the central section of the PPKF, we precisely mapped the fault trace, revealing a discontinuous geometry with a main fault strand and left-stepping segments in agreement with the position of the 2020 surface ruptures. To the north, the accumulated relief from this transpressive fault system decreases, and the fault trace becomes less distinct, suggesting a northward propagation of the deformation. Cumulative offsets of 4 to 24 meters along the main fault strands in the central and southern sections of the fault attest to its Quaternary activity. Dating results suggest offset markers at the Marine Isotopic Stage 4 (MIS 4), the Late Glacial Maximum (LGM) or the Early Holocene periods, allowing for the first direct estimation of the fault slip rates. Preliminary estimates indicate that, assuming a common MIS 4 or LGM age for the investigated markers, fault slip rates range from 0.2 to 0.7 mm/yr and 0.7 to 1.6 mm/yr, respectively. In contrast, assigning Early Holocene ages would imply much higher - and likely unrealistic - slip rates of 1.6 to 3.9 mm/yr. Although the estimated loading rates vary greatly and depend on strong assumptions regarding the age of the markers abandonment, our results suggest a minimum fault slip-rate of 0.2 mm/yr for local seismic hazard assessments.

Field surveys focused on detailed mapping and measurements of coseismic surface ruptures along the causative fault of the 6 February 2023, Mw 7.8 Kahramanmaraş earthquake. The aim was filling gaps in the previously available surface-faulting trace, validating the accuracy of data obtained from remote sensing, refining fault offset estimates, and gaining a deeper understanding of both the local and overall patterns of the main rupture strands. Measurements and observations confirm dominating sinistral strike-slip movement. An integrated and comprehensive slip distribution curve shows peaks reaching over 700 cm, highlighting the near-fault expressing up to 70% of the deep net offset. In general, the slip distribution curve shows a strong correlation with the larger north-eastern deformation of the geodetic far field dislocation field and major deep slip patches. The overall rupture trace is generally straight and narrow with significant geometric complexities at a local scale. This results in transtensional and transpressional secondary structures, as multi-strand positive and negative tectonic flowers, hosting different patterns of the mole-tracks at the outcrop scale. The comprehensive and detailed field survey allowed characterizing the structural framework and geometric complexity of the surface faulting, ensuring accurate offset measurements and the reliable interpretation of both morphological and geometric features.

The 2020 MW 6.4 Petrinja (Croatia) earthquake induced extensive and diversified liquefaction and lateral spreading phenomena within approximate to 20 km radius from the epicenter. A detailed investigation from field and Unmanned Aerial Vehicle (UAV) surveys was carried out by a European researcher team (EUTeam) in the months following the mainshock. This work focuses on 61 surveyed sites: field observations were coupled with laboratory tests for soil classification and sediment composition. The adopted procedure provides an in-depth geological and geotechnical characterization of the liquefied sites in the Petrinja region. The liquefaction evidences are mainly associated to alluvial plain environments, in particular to meander paleochannels, and the ejected material is predominantly siliciclastic, made up of very rounded quartz-rich lithics. Few sites are dominated by angular carbonate rock fragments, related to liquefaction in cataclastic deposits along tectonic fractures. The ejected sediment includes a wide range of grain-size from silt to gravel. The peculiar presence of gravel in the liquefied deposits (up to 28% in some samples) confirms the need of expanding the grain-size boundaries for liquefiable coarse-grained gravelly soils. The information gathered from the post-earthquake surveys and from the sedimentological and geotechnical analysis for each studied site were compiled in organized data sheets, providing a striking instrument for in-depth earthquake studies, both for geological and geotechnical engineering purposes. The format defined for the data sheet can be functional and applicable also in liquefaction studies from different geological and depositional settings.

Since 2019, the frequency of major explosive eruptions at Stromboli volcano (Italy) has increased, heightening the exposure of population and scientists to the hazards posed by ejecta. Morphological changes can directly alter the hazard potential associated with these phenomena. Here, we present a quantitative morphological analysis of changes of the crater terrace area linked to the 13 May 2022 major explosive event. High resolution (2.5 cm pixel(-1)) aerial imagery was acquired by unoccupied aircraft systems 2 hours before and 19 hours after the event. The 13 May 2022 major explosive event consisted of a minimum of seven explosions from four vents located in the south-central crater area. The opportune timing of this campaign enabled the quantification of morphological changes at Stromboli related to a single major explosive event at high temporal and spatial resolution. A total of 12.7 x 10(3) m(3) was excavated and 5.5 x 10(3) m(3) deposited. Via the mapping and classification of bomb distributions we observe that angular blocks make up the largest fraction of ballistics >0.2 m, from which we infer a strong interaction with wall rock and/or fragmentation of solidified plugs in the shallow plumbing system. The morphological changes observed provide valuable constraints on how much material is displaced, and the shift in location and the number of active vents during major explosive events at Stromboli.

Active insular volcanoes are generally characterized by their rapid morphological evolution, as a close interplay exists between eruptive activity and erosive-depositional processes in such volcanoes. The Sciara del Fuoco depression, a sector collapse scar on the NW flank of the Stromboli volcano (Italy), is considered a natural laboratory for studying the response of a volcanic slope to such a dynamic evolution. In this study, we report the very fast morphological evolution that affected the subaerial and submarine Sciara del Fuoco slope from May 2022 to May 2023, a period of time marked by the occurrence of two crater rim failures, pyroclastic density currents and multiple lava flows. The analysis of repeated topo-bathymetric surveys demonstrates that a narrow (100 m wide at maximum) and steep-sided canyon, tens of meters deep, formed in the central part of the Sciara del Fuoco. The canyon was mainly related to the erosive activity of the pyroclastic density currents, which led to the remobilization of (at least) 3.7 x 106 m3 volcanic material, mainly in the subaerial slope. The canyon was initially formed by retrogressive erosion upslope, starting from an initial submarine/coastal landslide. It then evolved through a progressive widening of its flanks through small-scale landslides. The study shows that landslide location, as well as the final canyon shape, were strongly controlled by the lithological limits of previous lava flows, highlighting the importance of inherited morpho-stratigraphy and lateral heterogeneities in slope stability. Since its formation, the canyon has acted as a main conduit for lava flows and volcaniclastic materials supplied on their way to the sea. About 1 x 106 m3 of material filled the subaerial canyon floor through time, and another 1 x 106 m3 of slope accretion was estimated for the submarine part of the Sciara del Fuoco, down to 400 m below sea level. Comparing the volumes associated with slope erosion and accretion, it is evident that a large part of the remobilized material bypassed the Sciara del Fuoco shallow-water sector and was emplaced at greater depths. This study highlights the relevance of an integrated system for monitoring the submarine and subaerial morphological evolution of insular volcanic flanks, contributing to an improved geohazard assessment during eruptive crises.

Paroxysmal eruptions, characterized by sudden and vigorous explosive activity, are frequent at open-vent volcanoes. Stromboli volcano, Italy, is well known for its nearly continuous degassing activity and mild explosions from the summit craters, occasionally punctuated by short-lived paroxysms. Here, we analyse multiparameter geophysical data recorded at Stromboli in early July 2024 during a period of activity that led to a paroxysmal eruption on 11 July. We use seismic, infrasound and ground deformation data, complemented by visual and unoccupied aircraft system observations, to identify key geophysical precursors to the explosive activity and to reconstruct the sequence of events. Elevated levels of volcanic tremor and very long period seismicity accompanied moderate explosive activity, lava emission and small collapses from the north crater, leading to a major explosion on 4 July 2024, at 12:16 UTC. Collapse activity from the north crater area continued throughout 7 July, while effusive activity occurred from two closely spaced vents located within Sciara del Fuoco, on the northwest flank of the volcano. On 11 July, a rapid increase in ground deformation preceded, by approximately 10 min, a paroxysmal event at 12:08 UTC; the explosion produced a 5 km high eruptive column and pyroclastic density currents along Sciara del Fuoco. Our observations suggest that the early activity in July was linked to eruption of resident magma within the shallowest parts of the volcano plumbing. This was followed by lowering of the magma level within the conduit system as confirmed by the location of newly opened effusive vents. Rapid ground deformation before the paroxysmal explosion on 11 July is consistent with the expansion of a gas-rich magma rising from depth, similar to past energetic explosive events at Stromboli. Our findings offer valuable insights into Stromboli's eruptive dynamics and other open-conduit volcanoes, highlighting the importance of integrated geophysical observations for understanding eruption dynamics forecasting, and associated risk mitigation.

Digital surface models reproduce the 3D topography of a territory at different spatial resolutions depending on the acquisition technique of source data. In active and densely populated volcanic areas, updated digital topographies are fundamental for mapping and quantifying the morphological changes generated by the eruptive events and play a key role in modelling volcanic phenomena and related hazards. This work presents the high-resolution Digital Surface Model of Stromboli Island, Italy, updated to 4th August 2023. The model, obtained by elaborating more than 109 × 106 Airborne Lidar points (x,y,z), reconstructs the volcano’s surface through an elevation matrix at a spatial resolution of 50 cm, reproducing both natural and anthropic elements. The model has been validated by using Ground Control Points and the vertical accuracy results in 8 cm. Nowadays, this model represents the most updated and accurate digital 3D topography of the entire island and, for this reason, can be considered a relevant data not only for multi-temporal morphological and volcanological analyses but also for hazard assessment studies.

Etna is one of the most active volcanoes in the world, with almost continuous eruptive activity from its four summit craters resulting in frequent morphological variation of its upper area. The summit area is frequently site of effusive and explosive activity, but also of local flank collapses of the summit cones and pyroclastic flows with different triggering mechanisms. Such a dynamic environment requires a thorough understanding of its temporal evolution in order to properly assess the state of the volcano over time, and infer further insight into its potential hazard. Voragine (VOR), formerly called the Central Crater, is the oldest and has been depicted on topographic maps since at least 1865; the NE-Crater (NEC) cone was born in 1911; the Bocca Nuova started as a pit crater next to Voragine in 1968, and the SE-Crater (SEC) cone started in 1971. Since 2011, a new cone grew on the SEC eastern lower flank during a series of paroxysmal episodes and it progressive coalesced with the SEC cone. To properly model the temporal changes of the summit area, we exploited archival topographic maps and aerial photogrammetric stereo-pairs. This reconstruction started from the digitising and processing of topographic maps that were produced on 1897, 1932, and 1985. We also processed aerial stereo-images acquired since 1954. From these datasets we extracted Digital Elevation Models (DEMs) with 5-10 m pixel size. We integrated historical data with already available DEMs: the 1998 and 2001, interpolated from vector maps; the 2005, obtained from aerial photogrammetry; and the 2012, 2014 and 2015 derived from helicopter-acquired data. Finally, between 2017 and 2023 we performed UAS (unoccupied aerial systems) surveys to derive high-resolution DEMs and orthomosaics with sub-meter pixel size. This new multi-temporal Digital Elevation Models (DEMs), from ancient topographic maps and aerial photo as well as from recent and current UAS data, have been analysed through the ESRI ArcGIS software to reconstruct the topography and quantify the main morphological changes of Etna summit area. Our modelling increases the knowledge about the evolution and the behaviour of a frequently active volcano, thus enabling to mitigate the associated risks.

The Molise-Sannio region, in the axial portion of the Southern Apennines (Italy), is a fold-and-thrust belt where the Late Miocene to Early Pleistocene compressional tectonics has been overprinted by a younger extensional stress regime responsible for a significant degree of seismicity, and which is coexisting with strike-slip faulting to the north-east. Active faults in this area are known to be capable of generating M6+ earthquakes. The goal of the MOSAICMO project (Molise SAnnio integrated crustal Model) is to develop a comprehensive multiscale crustal model of the Molise-Sannio region by combining seismological, geophysical and geological data, with a specific focus on the Quaternary intramontane Bojano basin (BB). The latter is a NE-trending depression whose genesis is debated, since according to recent studies it appears to be controlled by a system of NE-dipping active fault segments present on the southern side, while other studies claim the importance of SW-dipping faults on the other side of the basin. Indeed, the subsurface geometry and deep structure of the BB are poorly constrained by available geological data, which hampers a correct recognition of the master faults and their possible seismogenic significance. Resolving this ambiguity is a priority task that can be accomplished through an integrated geological and geophysical approach. In this project framework, multi-disciplinary geophysical studies were conducted to study the BB at different scales and resolutions, by interpreting subsurface geophysical parameters (e.g. electrical resistivity, seismic velocities, etc.) in terms of lithology and mechanical properties. Electrical methods have proven to be a powerful tool in imaging complex subsurface geology. By measuring the resistance of subsurface materials to electrical current flow, these methods can differentiate between various geological structures such as faults, basin infill sediments and basement rock types, providing high spatial resolution and significant investigation depth. 3D electrical resistivity tomography has often been used in recent years to image conductive bodies covering high-resistivity structures, such as tectonic basins or hydrothermal systems in volcanic regions. Here, we present a challenging case study for 3D geoelectrical imaging: a continental tectonic basin filled with low to moderately resistive sediments emplaced on conductive clayey-arenaceous rocks. The integration of different resistivity data (ERT and ResLog) with other geophysical methods, like seismic and magnetic surveys, further refines subsurface imaging, ensuring robust and reliable geological interpretations. We present the first 3D electrical resistivity model of the BB, down to 500 m depth, complemented by several 2-D ERT profiles calibrated with shallow boreholes. Subsurface geophysical models were further constrained by a scientific drilling, 170-m-deep, that we performed also to obtain new stratigraphic and geochronological data on the basin sedimentary sequence. This represents an important contribution to the understanding of the regional seismotectonic setting and, locally, the seismogenic sources surrounding the BB.

Misterbianco, located on the southern slope of Mt. Etna (eastern Sicily), was destroyed in the past by two catastrophic events that raised the old town to the ground. The first was the great eruption of 1669, whose lava front buried dozens of villages encountered along its path, entirely destroying the architectural heritage of Etna's southern flank. The second event was the disastrous 1693 Val di Noto earthquake, which caused major destruction throughout south-eastern Sicily, also damaging the few still standing buildings in the town. The GPR survey performed at this site, 350 years after the eruption, allowed a first attempt of planimetric reconstruction of the San Nicolò Church. Starting from the site history, we present the results of an integrated approach that involves history, volcanology and geophysics aimed at addressing future archaeological excavations for the protection of archaeological and monumental assets in a difficult setting as this volcanic environment.

The gravitational instability of hot material deposited during eruptive activity can lead to the formation of glowing avalanches, commonly known as deposit-derived pyroclastic density currents (PDCs). These currents can travel hundreds of metres to several kilometres from the source at exceptionally high temperatures, posing a catastrophic hazard to areas surrounding steep-slope volcanoes. The occurrence of deposit-derived PDCs is often associated with crater rim failure, which can be triggered by various factors such as magma thrust from dike injection, magma fingering, bulging or less commonly, powerful explosions. Here, the in-depth study of data from the multi-parametric monitoring network operating on Stromboli (Italy), including video surveillance, seismicity and ground deformation data, complemented by remote topographic sensing data, has facilitated the understanding of the events leading to the crater rim collapse on 9 October and 4 December 2022. The failures resulted in the remobilisation of 6.4 ± 1.0 × 103 m3 and 88.9 ± 26.7 × 103 m3 of material for the 9 October and the 4 December 2022, respectively, which propagated as PDCs along the NW side of the volcano and reached the sea in a few tens of seconds. These events were characterised by a preparatory phase marked by an increase in magmatic pressure in the preceding weeks, which correlated with an increase in the displacement rate of the volcano’s summit. There was also an escalation in explosive degassing, evidenced by spattering accompanied by seismic tremors in the hours before the collapse. These events have been interpreted as an initial increase in magma vesicularity, followed by the release of gas once percolation threshold was reached. The degassing process induced densification of the magma, resulting in increased thrust on the conduit walls due to increased magmastatic pressure. This phase coincided with crater rim collapse, often followed or accompanied by the onset of lava overflow phases. A mechanism similar to the one proposed may shed light on similar phenomena observed at other volcanoes. The analysis performed in this study highlights the need for a multi-parametric and multi-platform approach to fully understand such complex phenomena. By integrating different data sources, including seismic, deformation and remote sensing data, it is possible to identify the phenomena associated with the different phases leading to crater rim collapse and the subsequent development of deposit-derived PDCs.

AbstractThe July 2024 eruption of Stromboli volcano has been characterised by the manifestation, at variable intensity, of the entire repertoire of volcanic events that Stromboli volcano is capable of, and is by far the one that has most changed the morphology of the crater terrace and of the Sciara del Fuoco slope in the last decades. We present the results of an Unoccupied Aircraft System (UAS) survey performed on 14 July 2024 and consisting of 4,988 visible and thermal photographs coupled with Structure-from-Motion photogrammetry that allowed us to produce a high-resolution (0.2 m/pixel) Digital Surface Model (DSM). We documented the profound morphological changes of the Stromboli volcano resulting from the 4–11 July 2024 eruption and obtained elevation and volume change estimates by differencing our survey and a UAS-derived pre-event surface (24 May 2024).

The Campo Felice basin, in the central Apennines seismic belt (Italy), developed in the hangingwall of a 30 km-long system of NW-trending normal faults with Holocene paleoseismic activity and potential sources of M 6-7 earthquakes. We provide the first subsurface images of a key portion of the basin bounded by the Mt. Cefalone fault along two intersecting profiles trending NNE-SSW (CF-Dip, 1195 m-long) and WNW-ESE (CF-Strike, 1315-m long). We combined high-resolution depth-migrated reflection sections with P-wave velocity and electrical re-sistivity tomography models. CF-Dip profile displays a wedge-like syn-tectonic sedimentary sequence of alluvial and glacial deposits with Vp similar to 2500-3000 m/s and resistivity > 500 Omega m in the hangingwall of Mt. Cefalone fault, overlying a high-Vp (>4000 m/s) limestone bedrock similar to 300 m deep. The whole sequence displays reflectors truncated by the Mt. Cefalone fault zone and subsidiary antithetic faults. CF-Strike profile, tied to three 80-110 m-deep boreholes, shows a thick fluvio-lacustrine sequence with low-Vp (<2000 m/s) and low resistivity (<100 Omega m), and a bedrock that deepens to the southeast (>450 m). Single-station ambient noise measurements display Horizontal to Vertical Spectral Ratios with peaks at similar to 1 Hz, decreasing to similar to 0.8 Hz to the southeast in agreement with the bedrock deepening indicated by seismic profiling. According to our results, the Campo Felice basin is a deep asymmetric half-graben controlled by faulting whose activity likely started before the Middle Pleistocene. Our minimum displacement estimate accrued in the past 0.5 Ma by the Mt. Cefalone fault is in the range of similar to 100-250 m.

The ability to image the underground structures of volcanoes is limited by the precision, resolution and pene-tration depth of each single geophysical method. In order to improve the knowledge of specific volcanic edifices and to better understand the general behavior of structures, the use of a combination of methods is strongly recommended to exploit and maximize their complementary capabilities of resolution and penetration depths. In this work a large dataset of seismic and electromagnetic measurements has been used to provide a more detailed and improved geophysical image of the shallower portion of the northern sector of Ischia Island (Campania region, Italy), severely hit by the August 21, 2017 earthquake (Mw 3.9). We analysed data by using different methodologies: Horizontal-to-Vertical Spectral Ratio (HVSR), seismic array technique (f-k), polarization analysis and Time Domain ElectroMagnetic (TDEM) survey. These methods are sensitive in a different way to tectonic features, lithologies, layer geometry and fluid distribution. Thus, their combination is useful for studying sites with complex crustal structures such as Ischia island, which is characterized by a well-developed geothermal system linked to the presence of a shallow magmatic body. Results of our study provides detailed information of the physical properties of the subsoil through: 1) the spatial distribution of the amplification parameters of ground motion, showing frequency peaks below 1 Hz and/or between 1 Hz and 5 Hz; 2) the definition of the velocity models up to 600 m depth, with shear wave velocities ranging from 150 m/s for the shallower layers to 2500 m/s for the half space; 3) the recognition of the correlation between the principal fault structures and polarization directions of the noise wavefield, mostly oriented along EW and NE-SW directions; 4) the resistivity models of the first 80 m depth with high resistivity values of the shallow layers in the range 50-100 omega.m and low resistivity values of the bottom layers in the range 1-10 omega.m.

Europe has experienced over the last years earthquakes of moderate magnitude (Mw 5-6), yet destructive, reminding us of the seismogenic potential of slowly deforming regions. Among them, the 2020 Mw 6.4 Petrinja earthquake ruptured the Petrinja-Pokupsko Fault (PPKF) in Central Croatia, about 50-km southeast of Zagreb, a region in which the caracterisation of seismogenic faults had been insufficiently studied before that event. Understanding the strain accommodation through time and space is critical for accurate assessment of the regional seismic hazard.Using field observations and high-resolution topographical data derived from airborne LiDAR (~10 cm resolution) and tri-stereo satellite images (Pléiades, resolution 50 cm), we accurately mapped the fault trace, underlined at several sites by geomorphic markers such as valleys, terrace risers, and alluvial fans that have recorded cumulative displacements ranging from 5 to > 50 m and potentially up to ~180 m. Along the studied section, our fault mapping is composed of a clear NW-SE-trending 10-km-long strand between Donja and Cepelis, and of 1-4-km-long right-stepping segments marked by a non-negligible vertical component. The southern strand is composed of 2-3 sub-parallel segments that accommodate the deformation within a < 500 m wide fault zone.We have identified several sites on the main southern strand where offsets have been accurately measured and where displaced markers have been sampled for cosmogenic nuclide exposure dating and radiocarbon datings. This will allow to estimate the slip-rate for this fault at different sites and over several time spans.The mapped fault appears very discontinuous with the deformation absorbed by a series of small fault sections rather than on a single fault strand. This likely reflects a recent transpressive deformation, with immature faults, in agreement with the source parameter of the 2020 Petrinja earthquake derived from seismology.Finaly, the 2020 coseismic surface ruptures affected the northern section of the PPKF, while the mapped cumulative displacements appears more prominent along the southern section. A better knowledge of the seismic history of this entire fault system is thus crucial for seismic hazard assessment of this area.