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We conducted large-depth Ground-Penetrating Radar investigations of the seismogenic Casamicciola fault system at the volcanic island of Ischia, with the aim of constraining the source characteristics of this active and capable fault system. On 21 August 2017, a shallow (hypocentral depth of 1.2 km), moderate (Md = 4.0) earthquake hit the island, causing severe damage and two fatalities. This was the first damaging earthquake recorded on the volcanic island of Ischia from the beginning of the instrumental era. Our survey was performed using the Loza low-frequency (15–25 MHz) GPR system calibrated by TDEM results. The data highlighted variations in the electromagnetic signal due to the presence of contacts, i.e., faults down to a depth larger than 100 m below the surface. These signal variations match with the position of the synthetic and antithetic active fault system bordering the Casamicciola Holocene graben. Our study highlights the importance of employing large-depth Ground-Penetrating Radar geophysical techniques for investigating active fault systems not only in their shallower parts, but also down to a few hundred meters’ depth, providing a contribution to the knowledge of seismic hazard studies on the island of Ischia and elsewhere.

The coastline of the Gulf of Naples, Italy, is characterized by a series of infrastructures of strategic importance, including touristic and commercial ports between Pozzuoli to Sorrento, main roads, railways, and urban areas. Furthermore, the Gulf of Naples hosts an intense traffic of touristic and commercial maritime routes. The risk associated with extreme marine events is hence very significant over this marine and coastal area. On 28 December 2020, the Gulf of Naples was hit by an extreme sea storm, with severe consequences. This study focuses on the waterfront area of Via Partenope, where the waves overrun the roadway, causing massive damage on coastal seawall, road edges, and touristic structures (primarily restaurants). Based on the analysis of the meteorological evolution of the sea storm and its effects on the waterfront, we suggest that reflective processes induced on the sea waves by the tuff cliffs at the base of Castel dell’Ovo had an impact in enhancing the local-scale waves magnitude. This caused in turn severe flooding of the roadway and produced widespread damage along the coast. The analysis of the event of 28 December 2020, also suggests the need of an effective mitigation policy in the management of coastal issues induced by extreme sea storm events. Wind-based analysis and prediction of the sea wave conditions are currently discussed in the literature; however, critical information on wave height is often missing or not sufficient for reliable forecasting. In order to improve our ability to forecast the effects of sea storm events on the coastline, it is necessary to analyze all the components of the coastal wave system, including wave diffraction and reflection phenomena and the tidal change. Our results suggest in fact that only an integrated approach to the analysis of all the physical and anthropic components of coastal system may provide a correct base of information for the stakeholders to address coastal zone planning and protection.

Unconventional geothermal resource development can contribute to increase power generation from renewable energy sources in countries without conventional hydrothermal reservoirs, which are usually associated with magmatic activity and extensional faulting, as well as to expand the generation in those regions where conventional resources are already used. Three recent drilling experiences focused on the characterization of unconventional resources are described and compared: the Campi Flegrei Deep Drilling Project (CFDDP) in Italy, the United Downs Deep Geothermal Power (UDDGP) project in the United Kingdom, and the DEEP Earth Energy Production in Canada. The main aspects of each project are described (geology, drilling, data collection, communication strategies) and compared to discuss challenges encountered at the tree sites considered, including a scientific drilling project (CFDDP) and two industrial ones (UDDGP and DEEP). The first project, at the first stage of pilot hole, although not reaching deep supercritical targets, showed extremely high, very rare thermal gradients even at shallow depths. Although each project has its own history, as well as social and economic context, the lessons learned at each drilling site can be used to further facilitate geothermal energy development.

The utility of new imaging technologies to better understand hazardous geological environments cannot be overstated. The combined use of unmanned aerial vehicles (UAV) and digital photogrammetry (DP) represents a rapidly evolving technique that permits geoscientists to obtain detailed spatial data. This can aid in rapid mapping and analyses of dynamic processes that are modifying contemporary landscapes, particularly through the creation of a time series of digital data to help monitor the geomorphological evolution of volcanic structures. Our study comprises a short-term (in geological terms) monitoring program of the dynamic and diffuse Pisciarelli degassing structure caused by the interplay between intensive rainfall and hydrothermal activity. This area, an unstable fumarole field located several hundred meters east of the Solfatara Crater of the Campi Flegrei caldera (southern Italy), is characterized by consistent soil degassing, fluid emission from ephemeral vents, and hot mud pools. This degassing activity is episodically accompanied by seismic swarms and macroscopic morphology changes such as the appearance of vigorously degassing vents, collapsing landslides, and bubbling mud. In late-2019 and 2020, we performed repeated photogrammetric UAV surveys using the Structure from Motion (SfM) technique. This approach allowed us to create dense 3D point clouds and digital orthophotos spanning one year of surveys. The results highlight the benefits of photogrammetry data using UAV for the accurate remote monitoring and mapping of active volcanoes and craters in harsh and dangerous environments.

Monitoring volcanic phenomena is a key question, for both volcanological research and for civil protection purposes. This is particularly true in densely populated volcanic areas, like the Campi Flegrei caldera, which includes part of the large city of Naples (Italy). Borehole monitoring of volcanoes is the most promising way to improve classical methods of surface monitoring, although not commonly applied yet. Fiber optics technology is the most practical and suitable way to operate in such high temperature and aggressive environmental conditions. In this paper, we describe a fiber optics Distributed Temperature Sensing (DTS) sensor, which has been designed to continuously measure temperature all along a 500 m. deep well drilled in the west side of Naples (Bagnoli area), lying in the Campi Flegrei volcanic area. It has then been installed as part of the international ‘Campi Flegrei Deep Drilling Project’, and is continuously operating, giving insight on the time variation of temperature along the whole borehole depth. Such continuous monitoring of temperature can in turn indicate volcanic processes linked to magma dynamics and/or to changes in the hydrothermal system. The developed monitoring system, working at bottom temperatures higher than 100 °C, demonstrates the feasibility and effectiveness of using DTS for borehole volcanic monitoring.

A temperature profile 2400 m along the off-shore active caldera of Campi Flegrei (Gulf of Pozzuoli) was obtained by the installation of a permanent fiber-optic monitoring system within the framework of the Innovative Monitoring for Coastal and Marine Environment (MON.I.C.A) project. The system consists of a submerged, reinforced, multi-fiber cable containing six single-mode telecom grade optical fibers that, exploiting the stimulated Brillouin scattering, provide distributed temperature sensing (DTS) with 1 m of spatial resolution. The obtained data show that the offshore caldera, at least along the monitored profile, has many points of heat discharge associated with fluid emission. A loose association between the temperature profile and the main structural features of the offshore caldera was also evidenced by comparing DTS data with a high-resolution reflection seismic survey. This represents an important advancement in the monitoring of this high-risk volcanic area, since temperature variations are among the precursors of magma migration towards the surface and are also crucial data in the study of caldera dynamics. The adopted system can also be applied to many other calderas which are often partially or largely submerged and hence difficult to monitor.