This study presents a comparative analysis of the two key example of sedimentary volcanism in Italy: the mud volcanoes of Salse di Nirano (Northern Italy) and the Maccalube of Aragona (Sicily). Mud volcanoes are not related to magmatic activity but result from the ascent of gas, mainly methane, which transports mud, water and fine-grained sediments to the surface These systems represent natural laboratories for investigating subsurface fluid migration, gas-driven processes, and their surface expressions.At both sites, mud and fluid samples were collected to perform geochemical, mineralogical, magnetic, and paleontological analyses, providing integrated constraints on fluid sources, sediment provenance, and mud volcano dynamicsDespite their apparent similarities, the two sites display markedly different genetic mechanisms and activity style. The study is carried out within the framework of the INGV-MUR project Pianeta Dinamico, called PROMUD.The Nirano mud volcanoes are characterized by slow and persistent activity, forming small and stable mud cones and bubbling pools. This behavior reflects the compressional tectonic setting of the Northern Apennines, where fractures facilitate the upward migration of fluids and hydrocarbons. The extruded material mainly consists of ARGILLE SCAGLIOSE, the main constituent of the volcanoes, marly clays rich in CaCO3, and Plio-Pleistocene clay sediments, while saline waters indicate an ancient marine depositional environment.In contrast, the Maccalube of Aragona area exhibits highly variable and sometimes violent activity, with bubbling mud pools and sudden eruptive events. Here, the mud composition derives from poorly consolidate shallow clayey sediments, and methane is generated within organic-rich sediments. Brackish waters are likely derived from compaction processes of marine sediments.The comparison highlights how similar fluid-driven process can produce contrasting surface features, levels of activity and hazard scenarios.

Natural gas seeps and mud volcanoes are widely distributed across terrestrial and shallow submarine sedimentary basins and contribute considerable amounts of fossil methane to the atmosphere. Methane emissions from these systems are commonly interpreted as dominantly thermogenic in origin; however, microbial activity may significantly contribute to, or overprint, these emissions through secondary methanogenesis or methane oxidation during gas migration and storage.Conventional bulk isotope composition (δ¹³C and δD) and hydrocarbon concentration ratios are often insufficient to distinguish secondary microbial contributions from an initial thermogenic source. Independent of bulk isotopic signatures, methane clumped isotopes (Δ¹³CH₃D and Δ¹²CH₂D₂) provide direct constraints on methane formation pathways and post-generation alteration processes. Recent studies have revealed low-temperature near-equilibrium clumped-isotope signatures in mud-volcano systems in Azerbaijan1, indicative of strong microbial overprinting, whereas methane from Japanese mud volcanoes exhibits clumped isotope signatures spanning from far from equilibrium to near equilibrium values2. For the latter, clumped isotope signatures of methane correlate with 13C-position-specific isotope composition of propane, suggesting the biodegradation of higher hydrocarbons is associated with progressive modification of methane clumped isotopes.Here, we investigate methane emissions from mud volcanoes and gas seeps in central and southern Italy (n = 14) and Romania (n = 15). Methane bulk and clumped isotope composition (δ¹³C, δD, Δ¹³CH₃D and Δ¹²CH₂D₂) are analyzed using a quantum cascade laser absorption spectrometer (QCLAS) equipped with a customized gas-inlet system at Empa3. Propane concentrations span from below detection to 0.8%, indicating a wide range of potential microbial influence. Selected samples are further characterized by propane position-specific isotope analyses at Science Tokyo following established protocols by Gilbert et al. 4, providing constraints on the extent of secondary microbial processes affecting higher hydrocarbons.Preliminary clumped-isotope results from Italian mud volcanoes indicate near-equilibrium signatures consistent with strong microbial influence, comparable to patterns reported from Azerbaijan mud-volcano systems. In contrast, Romanian samples exhibit pronounced variability in propane concentrations, providing a critical test case to explore whether methane clumped-isotope systematics transition toward more thermogenic-dominated patterns with secondary microbial influence, similar to those observed in Japanese systems. By integrating new datasets from Italy and Romania with published clumped-isotope and propane intramolecular isotope data, this study explores whether microbial influences on methane emissions follow consistent or system-specific patterns across mud-volcano and gas-seep systems globally. [1] Liu et al., 2023 Geology[2] Gilbert et al., 2025 EGU2025 Abstract[3] Zhang et al., 2025 Anal. Chem.[4] Gilbert et al. 2019 Proc. Natl. Acad. Sci.

The volcanic island of Nisyros, situated on the South Aegean Volcanic Arc, represents a critical site for studying the interactions between active magmatic-hydrothermal systems and structural tectonics. Following the 1998 seismic crisis and subsequent fumarolic activity, characterizing the island's subsurface has become essential for volcanic unrest monitoring. As part of the DEMETRA research line funded under the INGV ROSE infrastructure project, we present an unprecedented high-resolution 3D electrical resistivity model of Nisyros, reaching depths of 1.5 km.To overcome the logistical and topographical constraints of this sensitive Geopark environment, we deployed a non-invasive 3D network of 34 IRIS V-Fullwaver receivers, ensuring island-wide coverage from the central Lakki caldera to the volcanic slopes.Our 3D model provides a first-of-its-kind geophysical visualization of the island's hydrothermal system. Key findings include:Aquifer Identification: The detection of several hydrothermal aquifers, directly corroborated by historical geothermal boreholes (1983-1984).Structural Control: Precise imaging of the major NNW-SSE and NE-SW normal fault systems. These structures act as the primary conduits for fluid migration, establishing a definitive link between surface geothermal manifestations and deep aquifers.The success of this study demonstrates that Deep Electrical Resistivity Tomography (DERT) is a powerful and socially accepted tool for investigating sensitive volcanic environments. This 3D model significantly improves our understanding of Nisyros’ first kilometer, providing a robust baseline for future hydrothermal modeling and hazard mitigation.

Plastic contamination has become a global concern, with evidence even in remote regions like Antarctica. While macro- and microplastics have been documented in Antarctic marine ecosystems, their presence in soils - particularly submicro- and nanoplastics - remains poorly studied. This study analyses soil samples from the McMurdo Dry Valleys collected on January 8th to 28th, 2023, and reports the first detection of nanoplastics - including polypropylene, polyethylene, polyethylene terephthalate, polystyrene, polyvinyl chloride, and tyre wear particles - using thermal desorption proton transfer reaction mass spectrometry. These plastics were detected at multiple topsoil sampling sites (n = 13), with concentrations reaching up to 295 ng g⁻¹ with nanoplastics detected above polymer-specific method detection limits at 54% of sites (median: 26.6 ng g⁻¹). They were also detected at lower concentrations in deeper soil layers (> 20 cm; n = 4), where nanoplastics were present at 50% of the sampled sites (median: 1.95 ng g⁻¹). Lagrangian particle dispersion model FLEXPART suggested seasonal deposition patterns, with inputs from both local sources and long-range atmospheric transport. This evidence shows that soils in one of Earth's most pristine environments are not exempt from plastic contamination, with the reported concentrations providing a crucial baseline for global pollution assessments. These findings also highlight the urgent need to study plastic fate, transport, and ecological impacts in polar regions.

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.

Natural radionuclides in rocks, water, and organic matter are commonly used as tracers for studying geological and hydrological cycles, including groundwater movement. One of the most characteristic and successful applications of radioactivity in earth sciences is its use as a natural “clock” measuring successively processes, from minutes to billions of years, occurring on the Earth. In the framework of the multidisciplinary INGV-PROMUD research project, aimed at identifying key indicators of mud volcano activity and potential precursors of paroxysmal events, aim of this study is to explore the potential of natural radioactivity as tracer for analysing long and short-term variation at Maccalube di Aragona Nature Reserve (Sicily, Italy). In order to define a “past status” (status zero) of the environment from which starting to analyse, in the future, variations of the global environmental system at specific times and space scale through also correlations with environmental factors, experimental campaigns were conducted between November 2023 and July 2025, including a specific sampling phase, on September 2025, after a paroxysmal overturning event, registered on August 2025. The ‘baseline’ for the radiological characterization of the site was performed, by using gamma spectrometry, by measuring the content of 226Ra and 232Th and 40K and 137Cs in soil, mud and water samples, alongside in situ measurements of surface 222Rn and 220Rn emissions were completed for tracing short-term environmental variations. The experimental results reveal a concentration of 226Ra and 232Th and 40K lower than the global average and coherent with the expected geology of the area, as well as 137Cs concentrations below the detection limit was registered, indicating the absence of anthropogenic radiocesium contamination within the sensitivity limits of the applied method. On the other side, the 222Rn surface emissions from soil registered high activity concentrations in well localized points coherent with the active surface manifestations of the sedimentary volcanism which characterizes the study area, whereas the scarcity of surface 220Rn is best explained by the combined effect of rapid radioactive decay during upward migration and the low permeability of the compact clay-rich upper layer, rather than by a simple absence of shallow thoron in the system.

Radon (²²Rn) is a naturally occurring radioactive gas that occurs in rocks and soils, and its migration pathways are influenced by geological faults. These processes can significantly increase radon leakage into buildings, posing a significant health risk. Classified as a carcinogen by the World Health Organisation, exposure to radon has required the establishment of national reference levels across Europe under Directive 2013/59/EURATOM and the identification of Radon Priority Areas (RPAs) to guide remediation initiatives. This legislation emphasises the need for both collective and individual risk management, using advanced radon risk assessment tools.In this study, we present an innovative approach to construct a geogenic radon hazard index (GRHI) map for Italy using a robust bottom-up methodology. Our approach integrates several geological proxies related to radon source (e.g. geology, radionuclide content) and migration pathways (e.g. faults) using supervised auto-machine learning (Autogluon). A dataset of approximately 30,000 soil radon measurements was divided into training and test datasets. A conceptual model with ten predictors was developed to estimate soil radon concentrations at unsampled locations on a 1x1 km grid. The LightGBMLarge algorithm resulted in the best model (R²test = 0.524) which was validated by a combination of statistical metrics. The SHAP analysis highlighted the relative importance of the predictors in the model.The GRHI map was further combined with census section data (ISTAT database) and population density to produce a risk map from Collective Risk Areas (CRA) to Individual Risk Areas (IRA). This final map serves as a valuable tool for national and regional administrations to identify IRAs in accordance with Directive 2013/59/EURATOM (Article 103).This research addresses the lack of a standardised European methodology for radon risk assessment. It provides a comprehensive framework to bridge the gap between collective and individual risk. Through the integration of geological knowledge with machine learning and demographic data, this work provides useful information for the improvement of radiation protection and public health strategies.

Assessing leakage mechanisms that compromise reservoir integrity is essential for effective geo-resource management and mitigating environmental risks. Reservoir leakages can occur via both anthropogenic pathways, such as active and inactive wells and pipelines, and natural pathways, including fractures and fault zones. Additionally, fault-valve action can temporarily disrupt sealing layers, allowing trapped fluids to migrate upward. Distinguishing between natural and human-induced causes of reservoir leakage is valuable but often challenging. To address this, we present an innovative approach that compares fluid circulation systems before and after the onset of reservoir exploitation. Present-day fluids are studied using standard groundwater sampling, modelling, and near-surface soil gas surveys. In contrast, paleo-fluids are analyzed using carbonate clumped isotope of fault-related calcite veins, along with fluid inclusion spectroscopy and microthermometry to determine parental fluid temperatures and compositions. We applied this approach to the giant Val d’Agri hydrocarbon reservoir in Southern Italy, a region characterized by: (i) high seismic hazard, with historical earthquakes up to magnitude 7; (ii) recent low-magnitude seismicity induced by oil extraction; and (iii) ongoing debate about industrial activities potentially triggering anthropogenic leakages. From our extensive dataset of fault-related calcite veins, we selected samples from Pleistocene-Holocene extensional-transtensional faults of the northeastern side of the valley, where productive oil wells are located. Carbonate clumped isotope analysis revealed precipitation temperatures of 160-180°C, while micro-Raman spectroscopy of fluid inclusions detected hydrocarbon phases matching those currently extracted from the reservoir. These findings suggest that past faulting, likely associated with strong earthquakes, temporarily breached the thick sealing layer, releasing trapped hydrocarbons. Considering present-day fluids, isotope analyses (carbon, boron, sulfate, and helium) from hydrogeochemical monitoring of nearby springs indicated long-term mixing between these hydrocarbons and shallow fluids. In summary, our multidisciplinary study demonstrates that natural leakage via fault-valve action occurred in the pre-exploitation period. Given the high seismic hazard in this region, we recommend incorporating these natural processes into future assessments to enhance environmental hazard mitigation and support sustainable hydrocarbon production management.

Ciampino area has been the subject, from 1999 onwards, to reiterated geochemical surveys on soil-gas, spring waters and groundwater, commissioned by the municipality to INGV (National Institute of Geophysics and Volcanology). Indeed, this area is affected by huge CO2 emissions of volcanic origin and high levels of indoor radon. Both gases can constitute a big concern for local population known as Natural Gas Hazard (NGH). Accordingly, the distribution of the two gases in groundwater, soils and indoor buildings must be assessed in order to define sectors of the territory more exposed to NGH.Interest in the Natural Gas Hazard arose mainly starting from November 1995, when several homes, basements and wells were affected by widespread exhalations, to the point of danger to human health.The most area affected is characterized by abundant and concentrated gas leaks which caused the death of 29 cattle and some sheep in September 1999 and March 2000, until December 2000 when a paroxysmal episode caused the death of a man.The main activities carried out in the last 25 years have concerned:- sampling of water sites (about 100 natural springs, public and private wells), measuring chemical-physical parameters, CO2 and 222Rn contents;- monthly indoor radon measurements (around 500/year) in 14 selected sites (both private homes and workplaces, including schools);- measurements of radon in soils (about 300) to identify the areas with the greatest degassing and the possible relationship with existing tectonic structures;- continuous indoor radon measurements in a selected home;- spot measurements in groundwater and intervention in the event of reports from the municipality and/or private citizens of emergency situations resulting from gaseous emanations falling in areas of the municipal territory of Ciampino.The data obtained include measurements of flux and concentration of soil gases, distribution of pCO2 and radon in groundwater, radionuclide content in soils from different geological units, indoor radon measurements.All this data has allowed us to define the sectors at greatest risk, by identification and delimitation of NGH risk areas. Dissemination and information activities on the NGH were carried out through public meetings, seminars and the drafting of brochures. Also training activities for the staff of the Civil Protection and Environment Offices of the Municipality were performed.The experience gained has allowed the participation of INGV in a European project Life Respire for the monitoring and remediation of the radon problem.Based on the distribution of the different samples collected: soil gas, terrestrial gamma dose rate and rock/soil samples by radionuclide content, we were able to provide the local authorities the map of the geogenic potential of radon for the whole municipal territory.

Investigations carried out on 72 fluid samples from 59 sites spread over the area surrounding the Sea of Marmara show that their geochemical and isotopic features are related to different segment settings of the North Anatolian Fault Zone (NAFZ). We collected fluids from thermal and mineral waters including bubbling and dissolved gases. The outlet temperatures of the collected waters ranged from 14 to 97 °C with no temperature-related geochemical features. The free and dissolved gases are a mixture of shallow and mantle-derived components. The large variety of geochemical features comes from intense gas–water (GWI) and water–rock (WRI) interactions besides other processes occurring at relatively shallow depths. CO2 contents ranging from 0 to 98.1% and helium isotopic ratios from 0.11 to 4.43 Ra indicate contributions, variable from site to site, of mantle-derived volatiles in full agreement with former studies on the NAFZ. We propose that the widespread presence of mantle-derived volatiles cannot be related only to the lithospheric character of the NAFZ branches and magma intrusions have to be considered. Changes in the vertical permeability induced by fault movements and stress accumulation during seismogenesis, however, modify the shallow/deep ratio of the released fluids accordingly, laying the foundations for future monitoring activities.

The processes leading to high levels of arsenic, iron, and manganese in a naturally reducing aquifer beneath a landfill are investigated. Between 2016 and 2022, groundwater monitoring (physical-chemical parameters, major and trace inorganic compounds) has been complemented with the analysis of environmental isotopes (tritium, δ2H, and δ13C) of groundwater and of the dissolved gases (δ13C of CH4 and CO2, 14C of CH4). Statistics, including Pearson/Spearman correlation and PCA, were used to define the main correlation among variables. The presence of methane and carbon dioxide was attributed to landfill gas migration from the waste as 14C dating confirmed that methane is modern (F14C = 1.0684) and likely produced by methyl fermentation within the waste. While methane, enhancing the naturally reducing conditions of the aquifer, appears to be the driver of the high concentration of Fe and As, Mn appears to be governed by carbon dioxide. At the same time, CO2 may locally lower the pH, thus increasing the dissolution of sedimentary carbonates and ultimately producing high alkalinity and salinity. Furthermore, the reuse of water from leachate treatment to meet circular economy requirements was invoked to explain the elevated levels of tritium and 2H, associated with significantly negative 13C, observed in a production well and in a nearby piezometer. The integration of environmental isotopes and geochemical parameters allowed to exclude leachate contamination: tritium, δ2H, and δ13C were within the expected range for natural groundwater. No compounds typical of leachate contamination were detected. Environmental isotopes can fruitfully complement traditional monitoring when the comprehension of processes is desired, but this requires an expert judgment and a solid conceptual hydrogeological model.

The intermediate-depth earthquakes usually occur at depths between 40-300 km, and are commonly related to deformation along and within the subducting plate. Promising but contrasting mechanisms of their seismic failure are proposed to model their generation and associated deformation processes, including ductile shear instability, dehydration embrittlement and failure of dry rocks. This work exploits one of the best examples worldwide of exposed sources of intermediate-depth earthquakes to better understand their nucleation environment. The study area consists of the Moncuni ultramafic massif (Southern Lanzo Massif, Western Italian Alps), a peridotite and gabbro section considered as a dry remnant of the Tethyan oceanic lithosphere subducted, during the Alpine orogeny, and then exhumed without experiencing ductile deformation and metamorphism. Moncuni geological units are extensively crossed by a network of pseudotachylytes (geological product of seismic slip associated to earthquakes), that locally preserve high-pressure minerals, suggesting an intermediate-depth seismic environment origin.In this study, we want to better understand the nucleation environment of intermediate-depth earthquakes by peeking into the deeper structure of the ophiolitic peridotite and gabbro of the Moncuni area. We are performing a Nodal Ambient Noise Tomography (NANT), which allows crustal imaging based on the measurement of short-period surface wave dispersion curves between pairs of seismic stations. The used dataset was acquired by installing a temporary seismic network with 197 three-component nodal geophones over 250 km2 area surronunding the Moncuni massif and operating for about one month.To perform the ambient noise data processing, we followed the procedure of Bensen et al. (2007). Before using the data, we accomplished a careful data quality analysis by checking the possible occurrence of some perturbations, monitoring several parameters like recording time, and sensor absolute position and stability. We also computed power spectral density curves for each node to investigate the occurrence of anthropogenic noise, and to select the optimal frequency band to use for the NANT. NANT is being performed extracting the empirical Green's functions (EGFs) cross-correlating time series of noise recorded at pairs of stations, so using the frequency-time analysis (FTAN) as proposed in Bensen et al., (2007), we have produced a huge amount of dispersion curves, and we applied a machine learning approach, deep convolutional neural networks, to perform automatic picking and to attribute a quality picking score. We evaluate as reliable picks with a score > 0.7. Conversely, the picks with a score < 0.7 were checked and manually corrected. The dispersion curves will be used to construct a shear-wave velocity model of the study area, allowing us to obtain a detailed image of the deep structure of the Moncuni massif with the goal of understanding whether these earthquakes originate in presence of fluids or in dry oceanic slab.

The systematic sampling of the main fumaroles of Solfatara (Campi Flegrei, Italy) started during the bradyseismic crisis of 1983-84. In the late 1990s, diffusive CO2 emissions measurements also became part of the monitoring activity through systematic campaigns. In these 40 years of investigations almost unique databases were created including thousands of chemical and isotopic analyses of fumaroles and hundreds estimations of the diffuse CO2 emission. These databases provided the base of numerous geochemical and interdisciplinary scientific works to understand the processes occurring in the hydrothermal-magmatic system of Campi Flegrei, a caldera in unrest since 2005. The main results obtained by this effort indicate the pivotal role of magma degassing in the current crisis of Campi Flegrei. The deep magmatic fluids are injected into the hydrothermal system during episodes of magma degassing. These injections cause pressurization and heating of the hydrothermal systems, earthquakes, ground deformations, changes in fumarole compositions and escalating CO2 emission at the surface. The expulsion of these fluids constitutes the most energetic process currently occurring at Campi Flegrei; it is, in fact, more energetic than ground deformation and seismic activity. In this work, we present a review of these different aspects.

Groundwater systems can be perturbed by natural events such as climatic extremes and earthquakes, two complex phenomena that may also interact. This multidisciplinary study investigates their combined effect on groundwater in the Eastern Southern Alps (Italy), an active compressional zone, using hydrogeological, hydrogeochemical, and seismological data. Between May 2022 and May 2024, thirteen springs were monitored annually, with five sampled monthly for chemical-physical parameters, major and trace ions. Most springs show a Ca-HCO₃ facies, indicative of shallow karst circulation, whereas two (Canal and Colesei) exhibit a Ca-SO₄ facies, characterized by elevated Na, Cl, and temperatures, suggesting contributions from deeper sources. Stable isotopes of water and dissolved gases confirm meteoric origin for all springs, while 87Sr/86Sr, trace elements, and geothermometers further support deep inputs at Canal and Colesei. Statistical analyses (Principal Component Analysis and Change Point Detection) identified geochemical anomalies possibly linked to (i) prolonged drought, which reduced aquifer recharge and enhanced ion concentrations, and (ii) seismicity, notably a Mw 5.8 earthquake ∼245 km away, potentially varying mixing between shallow and deep systems. These results highlight the outstanding need for integrated monitoring to understand and manage groundwater resources, particularly in tectonically active and densely populated areas facing climate change and extreme events.

Alteration by rock-fluid interaction can significantly impact rock and soil properties influencing fluid flow within hydrothermal aquifers, and shaping surface features and degassing in geothermal settings over time. Hence, the understanding of the spatial distribution of thermal manifestations in correlation with the geological setting and alteration type remains essential for unravelling the processes controlling the transport of fluids from within the hydrothermal aquifers to the surface. Previous studies focused on the effect of alteration within hydrothermal aquifers on a scale of hundreds of meters. In contrast, limited research has explored the influence of subsurface lithologies – including their intrinsic and altered permeability – and their spatial distribution on degassing activity. This study examines subsoil portions across the active geothermal fields of Krafla caldera in Iceland, to explore the relationship between various soils/lithologies and primary degassing areas. In particular, we investigate how hydrothermal alteration influences the petrophysical characteristics of these lithologies, thereby modulating surface-level fluid circulation. In two field campaigns carried out in 2022 and 2023, we assessed the in situ petrophysical properties of over 200 samples across 22 sites in the Víti and Hveragil regions. Moreover, we conducted subsoil diffuse CO2 flux measurements for specific profiles. Field permeability ranged from 10-11 to 10-16 m2, with CO2 fluxes varying between 1.25 to 2628.33 g/m2 day. Additionally, we examined the grain size distribution and the componentry of selected subsoil layers. Our findings delineate the presence of both active (thermal) and inactive (non-thermal) regions, depicting the variable impact of hydrothermal alteration on the subsoil properties. In active geothermal sites, the dominance of mineral dissolution/replacement facilitates the formation of preferential pathways for fluid flow. Within inactive areas, mineral cementation of pores and fractures appears to act as barriers to fluid movement. These outcomes offer crucial insights for comprehending and quantifying the effect of hydrothermal alteration on fluid dynamics, shedding light on the progression of surficial manifestations and degassing patterns within active geothermal areas.

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.