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.

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.