Vincenzo Di Fiore

Submarine mass failures (SMF) represent a potential tsunami source for densely populated coastal areas such as the Bay of Naples (southern Tyrrhenian Sea, Italy). This study applies a three-dimensional numerical modeling framework, combining GEOWAVE/TOPICS and FUNWAVE, to simulate tsunami generation, propagation, and nearshore impact associated with two geomorphologically plausible submarine landslides located at the Dohrn Canyon head and along the Ischia Bank slope. A third configuration considers their combined activation within a deterministic scenario-based approach. The simulations highlight the rapidity of near-field tsunami impact, with waves reaching all monitoring stations (Pozzuoli, Procida, Ischia, Napoli, Sorrento, and Capri) within a few minutes from slide initiation (e.g., arrival times as short as 201 s). The spatial distribution of maximum wave amplitude (MWA) shows significant variability, reflecting the influence of source location, bathymetry, and coastal morphology. In addition to MWA, a cumulative energy indicator (E _tot ), obtained by integrating the squared free-surface elevation over time, was evaluated at each virtual gauge. The results indicate that MWA and cumulative energy do not scale linearly. For example, in the combined multi-source scenario, a relatively high MWA of 4.15 m at Ischia (IS) corresponds to a cumulative energy lower than that recorded at other stations characterized by smaller peak amplitudes. This behavior reflects the influence of wave-train duration, local bathymetric effects, and source orientation on energy redistribution. The findings suggest that, while MWA remains the primary parameter for hazard-oriented assessments, cumulative energy provides complementary information on the temporal persistence and overall hydraulic loading of tsunami signals in complex coastal environments.

This paper presents a new high-resolution magnetic map of the Solfatara crater, derived from magnetic gradient measurements. Using the gradient of the magnetic tensor, rather than the gradient of the magnetic vector, enhances the spatial resolution of magnetic anomalies. This case study demonstrates the superior capability of magnetic tensor gradient measurements in accurately locating and interpreting near-surface anomalies compared to standard magnetic methods. The new magnetic map of the inner part of Solfatara reveals clear NE and NW trends that align with Apennine and anti-Apennine structural orientations. The total magnetic intensity field is characterized by numerous short-wavelength anomalies (10–20 m), which are associated with shallow petrophysical and structural heterogeneities near the crater surface. The significance of this high-resolution magnetic dataset lies in its potential to improve the understanding and interpretation of the shallow hydrothermal system and volcanic features of Solfatara, a key site of the recent unrest at Campi Flegrei. Finally, we present an example of the joint application of full magnetic gradient tensor measurements and 3D electrical resistivity data for anomaly characterization.

In this study, we present the results of 76 Horizontal-to-Vertical Spectral Ratio (HVSR) measurements carried out near three active fault lineaments on the eastern flank of Mt. Etna (Santa Tecla-Linera, Fiandaca and Trecastagni). In this area, earthquakes are very shallow (within 2 km of depth) and produce surface fracturing and deformations around the identified emerging fault zones, even for moderate magnitude (Mw > 3.5), leading to widespread damage to buildings. Therefore, accurately identifying the zones affected by surface faulting is fundamental for improving territorial management.The dataset was processed using HVSR technique to obtain the HVSR curves and the related spectra, as well as to extrapolate information on the directional effects of the signals as a function of both frequency and azimuth. In the literature, the HVSR method has been successfully used to detect polarization effects across fault zones: previous studies have shown that horizontal polarization in Mt. Etna is often strong and tends to be perpendicular to the predominant fracture field or has high-angle polarization from the fault strike (Rigano et al. 2008; Di Giulio et al., 2009). We thus applied the wavefield polarization analysis to the ambient noise measurements to investigate the areal pattern of horizontal polarization and to identify any existing spatial variations. Moreover, the polarization angles were also estimated by using the Matlab code POLARGUI (Huailiang Li et al., 2021). This method allowed us to map the polar histograms and display the distributions of polarization azimuths in different frequency bands. The code is based on the decomposition of the eigenvectors and eigenvalues of the covariance matrix of the three ground motion components of Jurkevics (1988).Lastly, since fault zones may produce fault-zone trapped waves, which may consist primarily of Love-type waves with particle motion parallel to the fault strike (e.g. Lewis & Ben-Zion 2010) or may include Rayleigh-type components with different polarization angles (e.g Ellsworth & Malin 2011), we computed the ellipticity curves obtained with the RayDec method (Hobiger et al., 2009) to isolate the contribution of Rayleigh waves alone.The ellipticity of the Rayleigh waves was analyzed for all the measurements to identify any differences that might indicate the presence of a surface faulting zone. To emphasize the deviation between the HVSR curves and the ellipticity curves, a residuals analysis was performed based on the Root Mean Squared Error (RMSE).These results enabled the identification and proposal a new indicator as proxy for the presence of the fault system and/or any associated fracture field, to be integrated with other types of geophysical measurements.Acknowledgements: The measurements are part of the geophysical acquisitions for the ETNA-FAC project, signed by CNR IGAG with the Regional Department of Sicilian Civil Protection. The project involved: CNR IGAG, INGV, University of Catania, OGS, ISPRA, CNR ISPC and CNR IMAA.

The scientific project TESIRA (TEst Site IRpinia fAult), funded in 2021 by the University of Naples “Federico II”, aims, through the integration of a multivariate dataset, to achieve a high-resolution 3D geophysical imaging of the shallow structure of the southern branch of the 1980 Ms=6.9 Fault at Pantano San Gregorio Magno (SA). The set of data acquired during the project life-span included: a microgravimetric survey; 3D and 2D Electrical Resistivity measurements; aeromagnetic and GPR surveys by drone; a CO2 surface degassing measurement and a full-waver electric investigation. Specifically, the active-source seismic dataset acquired at Pantano consists of four high- to very-high resolution seismic profiles spanning a total length of 3150 m and a high-resolution seismic volume covering an area of 12.5 acres. The seismic experiment's location was strategically chosen to illuminate key features of the Pantano basin affected by coseismic surface faulting, such as the rupture during the November 23,1980 Irpinia earthquake and the southern segment of the Pantano-San Gregorio Fault System (PSGM).We share the early findings obtained through standard Common Depth Point processing and post-stack depth migration. Even at this initial stage, the results offer a clear picture of the intricate 3D structure of the basin, revealing a complex pattern of the carbonatic basement resulting from active faulting. Additionally, the seismic images underscore the evident influence of active faulting on the basin's formation and recent sedimentation. Future analyses, including full-waveform inversion and post-stack depth migration, are planned to enhance the imaging of this critical sector in the southern Apennines. Although seismic data present the highest resolution among the geophysical datasets at Pantano, their integration with the extensive data collected during the TESIRA project will facilitate a reliable interpretation of the complex basin subsurface, useful to improve our understanding of the interplay between active surface faulting and recent basin growth pattern.

In coastal alluvial plains, the variability of sedimentary inputs, tectonic and eustatism causes a complex subsurface geology which influences the position of fresh/saltwater interface. Furthermore, in these areas densely populated, the over-pumping of freshwater, coupled with the climate change events, promotes the landward migration of freshwater/saltwater boundary. This research illustrates the ability of geophysical tools to recognize the presence of salt/brackish water at Volturno Coastal Plain, Southern Italy. This area is characterized by a peculiar geological setting, due to the proximity at Somma–Vesuvio and Campi Flegrei volcanic areas, which profoundly influences the circulation of groundwater. The subsurface is mainly characterized by: (i) two denser layers located at − 10 m and − 20 m depth which in part prevents the vertical migration of groundwater, (ii) facies heteropy that facilitates the hydraulic connection between the different geological bodies, (iii) a discontinuous Campanian Ignimbrite deposits which favor the hydraulic connection between deeper and shallower aquifers. In this geological framework, 2D-ERT and 3D-ERT integrated with Downhole, Multichannel Analysis of Surface Waves and boreholes made possible to recognize the presence of two main zones with salt and brackish waters, respectively. The first zone, characterized by very low resistivity (≤ 1 Ωm) typical of salt water, stretches 1.5 km inland from the coast. The second zone, with a resistivity between 2 and 5 Ωm typical of brackish water, continues for other 3 km inland. This knowledge is useful for the engagement of all stakeholders (farmers, ranchers and policy makers) in the sustainable use of fresh water and for making water management plan operational tools.

The central‐eastern sector of the Phlegraean Fields caldera, southern Italy, is one of the most intensely studied and monitored volcanic active area of the word. This area reveals typical characters of a high‐ enthalpy geothermal systems. However, recently the presence of two different geothermal reservoirs has been outlined: one located in the central sector dominated by highly active vapours generated by episodic arrival of CO2‐rich magmatic fluids and the other one located in the eastern sector (Agnano zone) characterized by a shallow (400-500 m b.s.l.) still hot reservoir, heated by the upward circulation of deep no magmatic hot vapor.In this study we present preliminary results deriving from the integration of different geophysical surveys carried out in the Agnano plain area, in the frame of the GEOGRID research project. We acquired high-resolution gravity data along two parallel profiles and we investigated the depth, shape and density contrast of the subsurface structures by the CompactDEXP (CDEXP) method, a multiscale iterative imaging technique based on the DEXP method. The resulting density models, together with DC resistivity and stratigraphic data, outlines the presence of a complex morphology of the Agnano subsoil characterized by a horst-graben structure. The importance of the structural lines identified by geophysical data, is also confirmed by the alignment of correlate outcropping thermal waters.

In this study, we propose a 3D numerical modeling of tsunami waves generated by an underwater landslide. The simulated gravity instabilities are located in the Gulf of Naples. The availability of a detailed bathymetric map both with a good knowledge of the local geology allowed us to obtain reliable simulation results. Submarine landslides in the Gulf of Naples can be considered a potential tsunami hazard for the following reason: some dated landslides in the Gulf of Naples, suggest that triggering conditions for these landslides are connected to the seismicity of the area. There are many geological evidences of tsunami events in Gulf of Naples. In fact, several papers describe the effects induced by geological events on the tsunami origin. GEOWAVE numerical model was employed to simulate tsunami generation and propagation. Model results revealed that this probable landslide tsunami is capable of generating high waves and considerable run-ups along the coasts of countries near the landslide zone. A further important role in this study is determined by the directionality of the landslide which strongly influences the tsunami energy.

In this study, we performed two electric resistivity tomography (ERT) profiles and a 3-D volume to characterize and reconstruct an active fault located at “Pantano di San Gregorio Magno”, an intramontane basin of Southern Apennines, Italy, shaped by the active tectonics and hit by the Ms= 6.9, Irpinia 1980 earthquake, generated by a fault rupturing the soil in Pantano. The overall Irpinia Fault has a total length of about 40 km and with a thickness of the seismogenic layer of 8-10 km. The Irpinia Fault is among the faults with highest seismogenic potential in the Mediterranean region, causing the 4th Italian earthquake of last century (1980, Ms=6.9, Pantosti & Valensise, 1990) and generating a modest surface throw at Pantano San Gregorio Magno (SA). The basin is filled by lacustrine sediments, bassing laterally into alluvial fans and slope debris, laying over Mesozoic carbonate bedrock. The two 2D ERT surveys and the 3D volume allowed us to obtain high resolution images of the electrical resistivity of the subsoil both in 2D and in 3D. The results provided us with an opportunity to achieve a better understanding of the geometry of the active fault. The filling sediments are characterized by resistivity ranging from 10 to 150 Ohm m while the Mesozoic carbonate bedrock from 500 up to 1500 Ohm m. Furthermore, strong resistivity gradients are consistent with the tectonic structure characterizing the active fault.

The scientific project TESIRA (TEst Site IRpinia fAult), funded in 2021 by the University of Naples “Federico II”, aims at acquiring multidisciplinary geophysical data above an active fault in an intramontane basin of the Southern Apennines and to achieve, through the integration of this multivariate dataset, an accurate 3D geophysical imaging of the shallow structure of the fault zone in order to understand the link between shallow faulting and petrophysical changes, which affect rock permeability and surface degassing. The target structure is the southern branch of the Irpinia Fault, one of the structures with highest seismogenic potential in the Mediterranean region, causing the 4th Italian earthquake of last century (1980, Ms=6.9, Pantosti & Valensise, 1990) and generating a modest surface throw at Pantano San Gregorio Magno (Salerno).A microgravimetric survey and a 3D and 2D Electrical Resistivity measurements survey were acquired between September 2021 and January 2022. 3D seismic data were acquired in July 2022, using two overlapping arrays with a dense geophone distribution covering an area of about four hectares, with a detail of 2.5x2.5m. Moreover, four 2D seismic profiles intersect the 3D volume. An aeromagnetic survey, an extension of the gravimetric survey and a sampling of the CO2 surface degassing will be completed within this year. We will show the preliminary results of the individual surveys. Later, the different geophysical and geochemical measurements will be integrated using cooperative inversion and machine learning techniques. We hope that this multidisciplinary approach will provide a more comprehensive understanding of the interaction between surface faulting and basin development in this key area of the Southern Apennines. ReferencesPantosti, D.; Valensise, G.; [1990] Faulting Mechanism and Complexity of the November 23, 1980, Campania-Lucania Earthquake, Inferred From Surface Observations, JGR, 95, 319-34