Livio Ruggiero

Natural sinkholes are a widespread geohazard in Italy, complicating landuse planning and risk reduction. This study develops the first national-scale susceptibility map for natural sinkholes using an updated inventory and data-driven modelling. Building on the ISPRA National Sinkhole Database, we assembled more than 14,000 documented features from literature, historical records, imagery and regional datasets. Geological, geomorphological, structural, hydrogeological and geochemical factors were converted into gridded predictors and combined with the inventory through a machine-learning regression framework estimating a continuous susceptibility score. The calibrated model, evaluated on a held-out 20% test subset, produces a susceptibility surface for the Italian territory. Interpretation tools emphasize the importance of soluble rocks, fault-controlled permeability, deep gas emissions and mineralized springs, consistent with previous studies. High-susceptibility zones align with major karst and evaporitic provinces, including the Friuli-Veneto piedmont, northern Apulia, Latium travertine basins and central Sicilian evaporites, whereas western Alpine sectors and Sardinia show very low scores. The map offers a coherent national overview of where natural sinkholes are more likely to occur and provides an operational basis for prioritizing surveys, monitoring programmes and planning measures, while the methodology can be refined to incorporate time-dependent drivers and multi-hazard interactions. These advances support more resilient and sustainable territorial development.

Anthropogenic sinkholes are a major urban geohazard in Rome, where they are primarily associated with the collapse of artificial underground cavities and failures in water supply and sewer networks. Fragmented knowledge of subsurface tunnel systems, together with extensive urban development over undocumented and untreated voids, significantly increases structural vulnerability and exposure to sudden ground failures. Since 2008, ISPRA has conducted the most comprehensive inventory of anthropogenic sinkholes in the city, documenting more than 4,500 events since the early twentieth century. In cooperation with National Research Council of Italy – Institute of Environmental Geology and Geoengineering (CNRIGAG), susceptibility zones have been identified across several urban districts, supporting the delineation of areas characterized by higher collapse probability. During the last four decades, sinkhole frequency has increased markedly, with a sharp escalation after 2012, when annual occurrences often exceeded one hundred events. The maximum was recorded in 2018, with 175 sinkholes within the ring road around Rome (Ring Road – GRA) a motorway that circles the city and connects the main roads leading to and from Rome. This upward trend is correlated with intense rainfall events, climate-change-driven hydrological variability, and recurrent flooding, which promote subsurface erosion and cavity destabilization. The spatial and genetic complexity of these processes produces a susceptibility scenario that is difficult to predict and mitigate. Consequently, detailed susceptibility mapping is essential to support land-use planning, infrastructure management, and civil protection strategies. An initial susceptibility map was produced in 2015, followed by refined assessments in 2018 and further data updates and territorial analyses conducted by ISPRA between 2021 and 2023.

Volcanic plateaus in central and southern Italy, particularly in Lazio and Campania, have long been considered suitable for urban, industrial, and infrastructural developments due to their apparent stability and generally favourable geomorphological and geotechnical characteristics. However, both natural and anthropogenic sinkholes occur widely in these settings and are still largely underestimated in hazard assessment and land-use planning, as sinkhole processes are commonly associated only with karst and pseudokarst environments. Data from the Italian Sinkhole Database (ISPRA), updated within the framework of the Geosciences-IR project, highlight the significant occurrence of sinkholes in volcanic areas, including sectors hosting strategic infrastructure. Natural sinkholes are mainly related to groundwater-level fluctuations, gas emissions, structural discontinuities, and the presence of karstifiable travertine layers interbedded within pyroclastic successions. Anthropogenic sinkholes are also widespread, especially in urban and peri-urban areas, where they are associated with long-standing underground networks such as cuniculi, aqueducts, catacombs, and quarries, often reactivated or exacerbated by hydraulic failures and intense rainfall events. The updated inventory emphasises the need to consider sinkhole hazard as a relevant geological risk also in volcanic terrains and to incorporate dedicated mitigation strategies into land-use planning and infrastructure management.

Global warming has prompted globally widespread permafrost thawing, resulting in enhanced greenhouse gas release into the atmosphere. Studies conducted in the Northern Hemisphere reveal an alarming increase in permafrost thawing. However, similar data from Antarctica are scarce. We conducted a 2‐D Deep Electrical Resistivity Tomography (DERT) survey in Taylor Valley, Antarctica, to image the distribution of permafrost, its thicknesses, lower boundaries, and hydrogeology. Results show resistive, discontinuous domains that we suggest represent permafrost units. We also find highly conductive layers (5–10 Ω·m), between 300–350 m and 600–650 m below ground level and a shallower (∼50–100 m depth) conductive layer. The combined data set reveals a broad brine system in Taylor Valley, implying multi‐tiered groundwater circulation: a shallow, localized system linked with surface water bodies and a separate deeper, regional circulation system. The arrangement of these brines across different levels, coupled with the uneven permafrost distribution, underscores potential interplay between the two systems.

The occurrence of sinkhole phenomena in Italy is a prevalent and very uncertain class of geological hazards that pose a significant threat to human infrastructure and individuals. These events are characterized by their unpredictability and the challenges associated with their accurate forecasting. Both natural and anthropic factors influence the occurrence of these events; therefore, accurate identification of the above factors is critical for effective proactive and predictive efforts. The work presented in this paper refers to a collapse that occurred in a volcanic region in northern Latium (central Italy) on 31 January 2023. The area has been monitored using drones since the early stages of the sinkhole’s formation and has continued to date. Then, the collapse and the neighboring area were examined via geophysical and geochemical investigations to identify potential underlying factors. Geophysical and geochemical data were combined to provide a preliminary hypothesis on the collapse’s genesis. The obtained data indicate that the structural collapse can be attributable to the fluctuation in groundwater levels as well as the development of instabilities along its banks, leading to a growth in its dimensions.

Radon (222Rn) is a radioactive gas considered the major source of ionizing radiation exposure for the population and several epidemiological studies provided evidence of its detrimental effects on human health. As a consequence, the World Health Organization classified this gas as the second cause of lung cancer after cigarettes smoking. A significant fraction of lung cancer can be attributed to the indoor Rn exposure, i.e. houses and workplace. In particular, Indoor Radon Concentration (IRC) is the product of the Geogenic Radon Potential (GRP), conceptualised as the contribution of Rn released by the Earth. Therefore, in the characterisation of the potential risk over an area is fundamental considering the geological constraints under the dwellings, the building styles and living habits. In Europe, the Basic Safety Standards Directive 2013/59/EURATOM aims to reduce the human exposure to Rn in houses and workplace, on the one hand fixing some reference values, on the other hand requiring to the European states to delineate the Radon Priority Areas (RPA), i.e. that areas where IRC exceed the European Directive reference value. In particular, mapping the GRP as an indicator of the Rn related hazard is fundamental for: (i) delineate the RPAs through the quantification of geogenic Rn, that can potentially influx within buildings; (ii) understand how GRP can affect the vulnerability over an area thus contributing to the Rn risk. In this study, we focused on mapping the GRP of a specific study area located in the Pusteria Valley (Bolzano province, eastern Italy). This area is well-known from a geological and structural point of view and it is characterised by a wide non-seismically active fault zone showing a very high gas permeability. In particular, we have applied a machine learning technique (i.e. Forest Regression), to construct a high resolution (50 m*50 m) GRP map of the study area considering several proxy variables related to the Rn sources (e.g., radionuclide content in rocks), to the Tectonically Enhanced Radon (TER) quantity and to the exhalation process towards the atmosphere. Furthermore, we have assessed the vulnerability of the area by introducing the location of inhabited areas to provide a preliminary map of RPAs. Results show that dwellings characterised by high vulnerability are located in the area with the highest GRP. This work represents the first attempt in Italy to define the RPAs.

Warming global climate threatens the stability of the polar regions and may result in cascading broad impacts. Studies conducted on permafrost in the Arctic regions indicate that these areas may store almost twice the carbon currently present in the atmosphere. Therefore, permafrost thawing has the potential to magnify the warming effect by doubling the more direct anthropogenic impact from burning of fossil fuels, agriculture and changes in land use. Permafrost thawing may also intensify the Rn transport due to the increase of fluid saturation and permeability of the soil. A detailed study of 222Rn and 220Rn activity levels in polar soils constitutes a starting point to investigate gas migration processes as a function of the thawing permafrost. Although several studies have been carried out in the Arctic regions, there is little data available from the Southern Hemisphere. The Italian – New Zealand “SENECA” project aims to fill this gap and to provide the first evaluations of gas concentrations and emissions from permafrost and/or thawed shallow strata of the Taylor Valley, Antarctica. Taylor Valley is one of the few Antarctic regions that are not covered by ice and therefore is an ideal target for permafrost investigations. Results from our field measurements highlight very low values for 222Rn and higher values for 220Rn, suggesting a shallow source. Usually the measured 222Rn activity values are controlled by the radionuclide content in the soil, the temperature of the soil, the porosity of the soil, and the water content. We applied the Akerblom formula to calculate the radon at equilibrium with the activity concentration of the 226Ra on the collected soil samples, and the presence of 222Rn amounts higher than those naturally produced by the outcropping sediments is detected. These results demonstrate the presence of preferential gas pathways through the permafrost from a deep source. It is the first time that this type of study has been performed in Antarctica and can make a significant contribution to understanding the melting permafrost processes and its implications for the environment. This dataset also represents an important benchmark for future measurements to track the melt progress of Antarctic permafrost.

Radon is a natural radioactive gas produced by the decay of its parent nuclide in bearing rocks and soils. Inhalation of radon gas poses a serious risk for human health and the World Health Organization stated the doubtless correlation between long exposure to radon gas and lung cancer. In this context, 76 indoor radon measurements in private and public buildings were performed in the Ciampino municipality. This study was carried out within the framework of the LIFE-Respire project. Indoor radon concentration was measured by using passive nuclear track detectors (CR-39) and analysed using RADOSYS system at INGV Radionuclides laboratory. Measurements were carried out in winter and summer seasons to assess the range of seasonal fluctuations, as recognised elsewhere. Results show a substantial increase of maximum indoor values in winter (up to 1575 Bq/m3) that are two times higher than those measured in the summer period (up to 764 Bq/m3). The annual mean and median values (283 and 203 Bq/m3, respectively) are both below the EU recommended limit of 300 Bq/m3.Moreover, a questionnaire on radon risk perception was designed for the specific context of the LIFE-Respire project and distributed in a sample of residents and students in the Municipality of Ciampino to measure, among many other aspects, the salience of the hazard, knowledge of the hazard and of hazard mitigation strategies, perceived preparedness of and trust in officials, sources of received information and preferred methods of receiving information, and the level of interest in the project approach (including remediation measures).

Contemporary studies conducted in northern polar regions reveal that permafrost stability plays an important role in the modern carbon cycle as it potentially stores considerable quantities of greenhouse gases. Rapid and recent warming of the Arctic permafrost is resulting in significant greenhouse gas emission, both from physical and microbiological processes. The potential impact of greenhouse gas release from Antarctica is now also being investigated. In Antarctica, the McMurdo Dry Valleys comprise 10% of the ice-free soil surface areas in Antarctica and like the northern polar regions are also warming albeit from lower mean temperatures. The work presented herein examines a comprehensive sample suite of soil gases (e.g., CO2, CH4 and He) concentrations and CO2 flux measurements conducted in the Taylor Valley during the Austral summer 2019/2020. Analytical results reveal the presence of significant concentrations of CH4, CO2 and He (up to 18,447 ppmv, 34,400 ppmv and 6.49 ppmv, respectively) at the base of the active layer. When compared with the few previously obtained measurements, we observe increasing CO2 flux rates (estimated CO2 emission in the study area of 21.6 km2 ≈ 15 tons day-1). The distribution of the gas anomaly, when compared with geophysical investigations, implies an origin from deep brines migrating from inland (potentially from beneath the Antarctic Ice Sheet) towards the coast beneath the permafrost layer. These newly obtained data provide a baseline for future investigations aimed at monitoring the changing rate of greenhouse gas emission from Antarctic permafrost, and the potential origin of gases, as the southern polar region warms.