Clay-rich fault cores are commonly considered low-permeability barriers to across-fault fluid flow. However, increasing field-based evidence revealed syn-tectonic mineralizations within such fault cores, raising questions about their long-term hydraulic behavior, particularly during seismic events. This study investigates calcite veins and slickenfibres from the clay-rich fault core and damage zone of the 200-km-long strike-slip Yangsan Fault in South Korea, the major intraplate active fault in this region, by integrating structural and microstructural analyses with stable and clumped isotope geochemistry. Our data reveal that meteoric fluids downward infiltrated the fault damage zone over long time periods (possibly since late Cretaceous time), heated with depth according to the geothermal gradient, mixed with local formation water, and laterally infiltrated (i.e. across-fault) through a network of foliation planes into the clay-rich fault core, possibly affecting fault strength. We also propose meteoric water mixing with hydrothermal fluids derived by Late Cretaceous and Paleogene granite emplacement. We infer that mineralizations precipitated during different stages of the seismic cycle. Slickenfibres along fault-parallel foliation and shear planes probably precipitated during post-seismic to interseismic creep. Precipitation of foliation parallel extensional veins and stockwork veins probably occurred during the co-seismic phase due to earthquake fracturing. We speculate that transient pressurized fluid release may have occurred during the co-seismic phase. These findings challenge the prevailing view of clay-rich fault cores as static fluid barriers, instead pointing to a dynamic sealing behavior that evolves with the seismic cycles and over long-term geological timescales. Both slow, long-term interseismic fluid infiltration and rapid, short-term co-seismic fluid flow must be accounted for modeling the permeability of clay-rich faults in risk assessments for CO2 and H2 storage sites or for resource (hydrocarbons, geothermal fluids) exploration, especially in seismically active areas.

Seismic faults paradoxically combine high frictional strength, which promotes stress accumulation and should hinder slip, with large seismic displacements. Among proposed dynamic weakening mechanisms, shear heating is crucial because it triggers decarbonation and CO₂ production. In carbonate faults, this process generates transient CO₂ pressurization that can modulate rupture dynamics and promote supershear propagation, yet the amount and pressure of produced CO₂ remain poorly quantified. We investigate carbonate faults in the Apennines, Italy, a region affected by Mw≤7.1 earthquakes. Integrating nano-scale observations of fault surfaces with mineralogical and isotopic constraints, we develop a stoichiometric-thermodynamic model linking seismic decarbonation to Mw 5.9-6.5 earthquakes. Individual events can produce up to 12 tons of CO₂, generating quasi-lithostatic pressures ( ~ 196 MPa) under undrained confinement and supra-hydrostatic pressures (76-134 MPa) under drained conditions. Here, we conclude that seismic CO₂ pressurization can sustain dynamic slip and enhance the destructive potential of earthquakes in carbonate terrains.

The Apennines-Tyrrhenian Sea system allows us to investigate seismotectonics in coupled thrust belt and back-arc realms driven by subduction retreat, continental collision, and crustal delamination. Since the late Miocene, active extension has progressively migrated forelandward, in tandem with contraction, away from the Tyrrhenian back-arc basin, inactive since ~2 Ma, to become localized tens of kilometers from the active thrust front. Integrating geodetic, seismic, and geological data, here we show that lower-crustal delamination is presently the primary geodynamic driver of Apennine tectonics and seismicity. This delamination propagates via a continuous hinge; an elastic flexural framework anchors crustal extension, contraction, and short-term vertical movements around the migrating hinge. Our results provide a template for other mature retreating subduction systems, where the onset of delamination and later waning of back-arc opening do not arrest deformation, but instead transfer its locus to a migrating zone of intra-lithospheric decoupling that sustains active deformation and seismicity. Lower-crustal delamination acts as the primary driver of present-day seismicity and upper-crustal deformation of the Apennines, according to an integration of geodetic, seismic, and geological data within an elastic flexural model to investigate active Apennine-Tyrrhenian dynamics.

Abstract The Neogene mineralized region of the Colline Metallifere in southern Tuscany (Italy) provides a natural laboratory to investigate feedback between fluid–rock interaction, structurally controlled fluid flow, and hydrothermal ore mineralization. This study focuses on the Fe–Cu–Pb–Zn deposit of Fenice Capanne, located south of the active Larderello–Travale geothermal system, where marly–limestone caprocks of the Liguride Complex preserve evidence of permeability creation and destruction above a regional geothermal reservoir. A multidisciplinary approach was applied to reconstruct the evolution of the hydrothermal system. Two main alteration stages were identified. An early prograde, high‐temperature skarn metasomatism was associated with the growth of clinopyroxene–garnet assemblages and characterized by substantial gains in Si, Fe, Mn, and Ca, resulting in a large volume increase (up to ∼400%). Reaction‐induced fracturing generated secondary permeability, which superimposed on primary permeability related to bedding and lithological anisotropies, enhancing hydraulic connectivity. A subsequent retrograde stage, below ∼300°C, was driven by mixing between meteoric and saline magmatic‐derived fluids, or those derived from evaporite interaction, and resulted in renewed fracturing, brecciation, and extensive quartz–sulphide veining. These processes recorded cyclic variations in fluid composition, redox conditions, salinity, and boiling associated with transient pressure drops during hydraulic fracturing. Overall, the Ligurian marly–limestone sequence evolved from a low‐permeability sedimentary seal into a reactive mineralized system capable of sustaining transient hydrothermal circulation. Structural connectivity controlled by faulting and reaction‐induced fracturing governed both permeability evolution and mineralization. These results demonstrate that sedimentary caprocks can behave as dynamic components of the hydrothermal systems, with important implications for geothermal fluid flow, metal transport, and reservoir evolution.

Micrometric phyllosilicate films along fault slip surfaces (SSs) can drastically reduce friction, yet they are unexpected in clay-poor carbonate platforms. We inquire how a major carbonate-hosted, seismogenic strike-slip fault can develop weak slip interfaces and undergo dynamic weakening despite an intrinsically strong host rock. Along the Mattinata Fault (Gargano Promontory, southern Italy), we integrate structural mapping and drone-based virtual outcrops with microstructural, mineralogical, and geochemical analyses (optical microscopy, SEM/FESEM-EDS, EPMA, and XRD). We document micrometric illite- and kaolinite-rich microlayers (locally up to similar to 15 mu m thick) localized on some SSs, together with ultracataclasites and phyllosilicate-filled injection veins that emanate from these surfaces into otherwise nearly pure calcite host rocks. Microtextures, vein geometries, and mineral assemblages suggest that clay minerals were derived from outside the carbonate host rock and introduced by transient fluid pressurization during coseismic slip, reflecting episodic open-system behavior of the fault zone. Because high-velocity experiments show that even minimal amounts of phyllosilicates concentrated in thin films can promote strong dynamic weakening, our observations provide a field-based mechanism for rapid weakening and slip localization in carbonate-hosted foreland faults. More broadly, we show that seismogenic faults in carbonate may be (unexpectedly and cryptically) clay-bearing, with important consequences for rupture propagation and for laboratory and numerical models that commonly assume closed, clay-free systems.

Hydrocarbon seepage at the Earth's surface provides crucial insights into subsurface petroleum systems. This study investigates the role of seismic cycle dynamics in controlling vertical hydrocarbon migration by studying the Ragusa Oil Field, a long-exploited petroleum district in the Hyblean foreland domain of south-eastern Sicily (Italy). Inspired by oil spilling in the area that followed a seismic sequence in February 2016, a multiscale structural analysis was undertaken to explore the relationship between fault activity and oil mobilization. This study integrates mesoscale structural measurements, microstructural analysis of bitumen-bearing fault breccias, and 3D Dilation Tendency modelling under paleo- and present-day stress conditions to build a dynamic model of upward hydrocarbon migration and seepage at the Earth's surface during the seismic cycle in carbonate-hosted normal faults in a foreland setting. Evidence from abandoned asphalt mines and active seep sites reveals both stratigraphic layer-impregnation and localized fault/fracture-controlled oil pathways. Field observation and Dilation Tendency analysis indicate that vertical hydrocarbon migration may predominantly occur by fractures instability during seismic rupture allowing overpressured fluids to migrate vertically, mainly at fault intersections. These findings highlight the role of seismic deformation in controlling fractures instability and transient permeability changes which, in turn, facilitate hydrocarbon mobilization and leakage. Calcite clast aggregates within hydrocarbon-filled voids observed during microstructural investigations confirm episodic, pressure-driven fluidization consistent with co-seismic mobilization. Stratigraphic evidence of repeated seepage events in Quaternary alluvial deposits supports a model of cyclic hydrocarbon migration linked to stress variations during the seismic cycle. The novelty of this paper is that we document an hydrocarbon seepage process associated with modern seismicity, filling the gap of previous observations of hydrocarbon seepage speculatively associated with fossil earthquakes without a direct cause-effect link.

Identifying seismogenic faults in offshore regions presents significant challenges, particularly in achieving their precise geometry and kinematics. Geological data derived from deep-sea exploration and geophysical surveys are commonly used to characterize offshore active faults together with earthquake hypocentral locations. However, limitations may arise in the quantity and quality of geophysical available data, inhibiting the realization of accurate 3D models. Furthermore, the precise relocation of seismic events is demanding, especially in the depth domain, due to the limited azimuthal coverage and the minimum station-event distance that is well beyond the mean depth of the events. In this context, an interdisciplinary approach becomes imperative to mitigate over-interpretation and over-simplification in defining the seismogenic sources and establishing an all-encompassing rupture model. By means of an interdisciplinary (geological, seismological, and geodetic) approach, we investigate the outermost Northern Apennines fold-and-thrust belt front in the Adriatic Sea (Italy) involved in the Costa Marchigiana Pesarese seismic sequence started with the 9 November 2022 Mw 5.5 mainshock. Given the proximity of the mainshock and the subsequent seismic sequence to the urbanized coastline, where several cities are situated, characterizing the activated faults and the related estimation of ground displacement becomes crucial for seismic risk assessment and the tsunamigenic potential. We analysed the geological setting of the area by means of an accurate interpretation of numerous seismic reflection profiles and well data acquired over the past decades, which complemented the publicly available seismic data. The interpretation of this dataset, provided by oil companies, led to an accurate definition of the thrust systems highlighting both the geometry of the activated sector of the thrust front and its relation to potentially active adjacent faults. Moreover, the results show the strong influence of past paleogeography and paleomorphology on the evolution and geometry of this sector of the fold-and-thrust belt, including the buttressing effect of carbonate platforms and inherited highs. The resulting 3D model was integrated with seismological data and geodetic observations allowing us to well highlight the activated portion of the fault plane: strong motion data and continuous GNSS stations hosted by onshore (storage centers) and offshore (seabed-anchored hydrocarbon platforms) infrastructures were jointly inverted to retrieve the Mw 5.5 coseismic rupture history.

Calcite is a common syn-kinematic precipitate in upper crustal fault zones coating slickensides, forming slickenfibers, and infilling veins. Structural and geochemical analyses of fault-related calcites can be used to unravel the source, distribution, and mixing of parental fluids in association with past fault activity. Identifying deeply sourced fluids through syn-kinematic calcites is of paramount importance, as the correlation of the ascent of deep sourced fluids with strong earthquakes, may allow using hydrogeochemical modifications in groundwater as potential seismic precursors. In this study, we investigate the origin of syn-kinematic paleo-fluids that circulated along the Val d’Agri faults, in southern Italy. These faults bound an intermontane basin topping the largest onshore oil field in Western Europe. Since the Val d’Agri Basin is affected by natural seismicity and low magnitude oil production induced earthquakes, it is necessary to assess the potential threats of hydrocarbon fault leakage at shallow crustal levels. With this aim, we collected about 350 syn-tectonic calcites along high-angle extensional-transtensional fault zones. By combining macro- and micro- scale structural observations with carbonate isotopes (C, O, clumped, and Sr) and rare earth elements and yttrium (REY) geochemistry, we identified 5 fluid sources: (1) meteoric waters in geochemical and thermal disequilibrium with the host rocks, which interacted with superficial soil; (2) meteoric waters in geochemical disequilibrium and thermal equilibrium with the host rocks, which had limited interaction with the host rocks; (3) buffered fluids in geochemical and thermal equilibrium with the host rocks; (4) high temperature fluids in geochemical equilibrium and thermal disequilibrium with the host rocks, which ascended from the carbonate hydrocarbon reservoir; (5) hot meteoric waters in thermal and geochemical disequilibrium with the host rocks, which mixed with the deeply sourced fluids. The presence of multiple fluids is consistent with an open fault-related circulation system, which allowed mixing of shallow and deep fluids through the high-angle extensional-transtensional Val d’Agri faults. Given the societal and economic issues of this area, the recognized involvement of deep fluids during past fault activity is crucial for the context of oil exploration and production as well as for environmental monitoring. Furthermore, this suggests that the Val d’Agri Basin is an ideal region to explore fluid-fault relationships throughout the entire seismic cycle through local seismicity records and continuous groundwater monitoring.

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.

We investigate the structural control on paleofluid flow in the Mt. Conero anticline, Italy, located in the frontal part of the Apennines fold-and-thrust belt. This anticline can be considered as an exhumed analog for buried anticlines in the Adriatic offshore, currently exploited for hydrocarbons and potential geothermal reservoirs or CO2 storage sites in the future. By integrating field structural analyses, stable and clumped isotope geochemistry of carbonates, and U-Pb geochronology, we demonstrate that the structural evolution of the Mt. Conero anticline in a carbonate-siliciclastic succession is marked by: (1) pre-orogenic normal faulting and veining during foreland flexure, (2) layer-parallel shortening during early contraction, with the development of en-echelon bedperpendicular conjugate veins and stylolites, (3) syn-folding thrusting and strike-slip faulting, and (4) transtensional faulting during fold exhumation and extensional collapse. Fluid circulation took place in a closed system, predominantly involving formation water, such as marine pore water trapped during diagenesis. Effective sealing by clay-rich formations overlying the fractured, permeable carbonates, coupled with low displacement strike-slip faults and thrusts, prevented the ingress of meteoric fluids and/or the upward migration of deep (hydrothermal) fluids. Limited mixing between formation and meteoric waters in a semi-closed system was observed during fold exhumation and extensional collapse. Our results show that folds in the frontal part of offshore fold-and-thrust belts are likely to retain fluids trapped during diagenesis due to the preservation of sealing layers. This suggests that such anticlines can preserve hydrocarbon reservoirs and are excellent candidates for CO2 storage due to their low leakage potential, offering also good storage capacity for geothermal fluids. These results may represent a benchmark for offshore anticlines in the frontal part of other offshore foldand-thrust belts, particularly those with carbonate anticlines overlain by clay-rich sealing layers.

Devastating earthquakes continue to surprise scientists, especially when they exhibit unexpected characteristics, such as the 2023 doublet of Mw>7.5 earthquakes in a day along the same fault system in eastern Türkiye. These earthquakes struck the East Anatolian Fault, a major >600 km long tectonic boundary, separating the Anatolian, Arabian, and Eurasian plates, resulting in approximately 60,000 fatalities in Türkiye and Syria and causing more slip than expected. Occurrences of temporally and spatially close earthquakes are hence rare and unmissable opportunities to advance our understanding of active fault mechanics and regional hazard. Such superevents could be part of a supercycle, wherein the likelihood of a large earthquake is determined by accumulated strain rather than time since past earthquakes. To advance our understanding of multiple earthquakes along fault systems and hence of seismic supercycles, we compare tectonic and seismological features of the two 2023 earthquake sequences near Pazarcik and Elbistan with those of the two previous Mw≥6.1 sequences, which occurred in 2010 and 2020, respectively, near Elâzığ along the northeastern East Anatolian Fault. We examined the four strong sequences along the East Anatolian Fault within a multimillennial context of historical seismicity and discovered progressively younger and nonuniform earthquakes moving southwestward. This pattern corresponds to a general progression and dispersion of seismic ruptures southwestward and we use it as a proxy to understand the mechanism of at least two major supercycles identified over the last two millennia. The supercycles evolved from the northeast spreading southwestward with an increasing number of earthquakes. Earthquakes to the northeast are spatially and kinematically well channelized along the main fault, efficiently translating slip toward the southwest, where dispersed and kinematically nonuniform earthquakes are triggered by the push from the northeast, until a new supercycle restarts from the northeast. Insights from recent events offer a crucial framework for interpreting past supercycles and enhancing seismic hazard assessment, providing essential guidance for future mitigation strategies.

Rough surfaces known as stylolites are common geological features that are developed by pressure solution, especially in carbonate rocks, where they are used as strain markers and as stress gauges. As applications are developing in various geological settings, questions arise regarding the uncertainties associated with quantitative estimates of paleostress using stylolite roughness. This contribution reports for the first time a measurement of the temperature at which pressure solution was active by applying clumped isotopes thermometry to calcite cement found in jogs linking the tips of the stylolites. This authigenic calcite formed as a redistribution of the surrounding dissolved material by the same dissolution processes that formed the extensive stylolite network. We compare the depth derived from these temperatures to the depth calculated from the vertical stress inversion of a bedding parallel stylolite population documented on a slab of the Calcare Massiccio formation (early Jurassic) formerly collected in the Umbria-Marches Arcuate Ridge (Northern Apennines, Italy). We further validate the coevality between the jog development and the pressure solution by simulating the stress field around the stylolite tip. Calcite clumped isotopes constrain crystallization to temperatures between 35 and 40 °C from a common fluid with a δ18O signature around −1.3‰ SMOW. Additional δ18O isotopes on numerous jogs allows the range of precipitation temperature to be extended to from 25 to 53 °C, corresponding to a depth range of 650 to 1900 m. This may be directly compared to the results of stylolite roughness inversion for stress, which predict a range of vertical stress from 14 to 46 MPa, corresponding to depths from 400 to 2000 m. The overall correlation between these two independent depth estimates suggests that sedimentary stylolites can reliably be used as a depth gauge, independently of the thermal gradient. Beyond the method validation, our study also reveals some mechanisms of pressure solution and the associated p,T conditions favouring their development in carbonates.

Understanding the origin and distribution of damage within carbonate-hosted fault zones is crucial, yet it remains a complex challenge, which hampers the overall assessment of their mechanical and hydraulic structure. In carbonate-hosted fault zones, shattered to intensely brecciated non-cohesive rocks have been reported. Although their origin has been related to the propagation of multiple seismic ruptures, great uncertainties persist regarding their interpretation and distribution. The NW-SE striking, approximately 15 km long Roccapreturo Fault, in the central Apennines of Italy, is an intriguing case study where non-cohesive fault rock domains occur within its footwall damage zone. These domains elongate in a NE-SW direction for ~200 meters from the main slip surface. We employed a multiscale approach to better understand the distribution and origin of the non-cohesive fault rocks. The fault geometry and throw distribution along the main fault segments were characterized through fault-perpendicular geological cross-sections. Virtual outcrop models of key exposures, located in and around an abandoned quarry, were constructed using Structure from Motion-Multiview Stereo photogrammetry. These models utilized photos taken with a Mavic Mini 2 drone. The interpretation of virtual outcrop models, combined with classical fieldwork, allowed us to map the damage and minor fault strands. The Roccapreturo Fault displaces Cretaceous rocks originally deposited in various depositional environments. Along its strike, from NW to SE, the fault intersects rocks from internal or restricted carbonate platform, margin, and proximal slope to basin depositional environments. Notably, non-cohesive fault rocks are exposed between the margin and proximal slope rocks. This area coincides with the maximum throw of the fault, which is ca. 600 meters, and with the intersection with a system of pre-existing NE-SW-striking steeply dipping faults. At the outcrop scale, faults exhibit two preferred orientations, parallel and perpendicular to the main slip surfaces of the Roccapreturo Fault, respectively. The former ones show predominant dip-slip kinematics, while the latter ones show both dip-slip and strike-slip kinematics. We interpret the distribution of non-cohesive fault rocks along the Roccapreturo Fault as influenced by its intersection with the NE-SW fault system, where most of the slip accumulated. Accordingly, the pre-existing NE-SW faults accommodated transtensional slip during latest extensional deformation and coeval rock exhumation from depth. The transition of the Cretaceous depositional environments, which was accommodated by the NE-SW-striking faults, therefore highlights the pivotal role of pre-existing anisotropies in dictating the distribution of damage, particularly of non-cohesive fault rocks, in carbonate hosted faults.

In the western Mediterranean, the subduction of the Tethyan ocean has progressively come to an end, following the intervening continent-continent collision. Compressional deformation connected with the ongoing Africa (AF) – Eurasia (EU) convergence has therefore progressively resumed mostly along the southern passive margins of the Mediterranean back-arc basins. The use of geodetic, seismological, and pre-existing tectonic data recorded between the Gulf of Cadiz and the Ionian Sea helps to trace this nascent AF-EU boundary and constrain its kinematics. Based on these data, this plate boundary is detected, kinematically defined, and compared with the previously identified boundaries in the same region. The nascent boundary is articulated and formed by variably oriented inherited structures. It is characterized by a discrepancy between the general motion of Africa with respect to Eurasia and the local contractional/compressive axes deduced from geodetic and seismic data. The oblique convergence along the nascent boundary matches that recorded in other instances of subduction initiation elsewhere, but the average convergence rate equal to 5 mm/yr in the Mediterranean seems currently too small for such a subduction initiation. Based on the assumption of a future northward tectonic vergence (i.e., Eurasian foreland), the Tyrrhenian, Algerian, and Betic salients, the Oran and Fès recesses, and the Ionian, Trans-Alboran, and Gibraltar transfer zones are identified along the nascent boundary. The latter zones connect salients and recesses through strike-slip displacements. The Algerian offshore hosts a long segment of the boundary characterized by locally increased seismic rate and actual northward vergence that would suggest this area being the first nucleus of subduction initiation in the western Mediterranean.

The Messina Strait and surrounding areas are one of the most interesting regions of the western Mediterranean Sea, characterized by the complex interplay between the Mesozoic-Paleogene Ionian basin, where the Calabrian Arc accretionary prism extends towards the southeast, and the Neogene Tyrrhenian back-arc basin to the northwest. Complex fault networks with different kinematics, running from the inner side of the Calabrian arc through the Messina Strait and the Ionian coast of Sicily, as far as the Hyblean Plateau, result from the coexistence of different geodynamic settings in the area. Some of these faults are responsible for several of the largest earthquakes occurred in southern Italy and the Mediterranean Sea in recent times. Different works aimed at establishing a relationship between seismogenic sources and mapped faults, defining the location and rupture mechanism of some of these fault lineaments. Even tough, many uncertainties still exist for earthquakes occurred in offshore areas, where the fault kinematics and geometry are in some cases still poorly constrained. In this work, we focus on a group of offshore faults located between the northern sector of the Messina Strait and the Gioia Basin (southern Tyrrhenian Sea). We aim at understanding the kinematics and the style of deformation in this area, and to investigate the role played by the main fault networks in the framework of the regional complex geodynamic setting of the Ionian-Tyrrhenian transition zone. This study is based on the interpretation of a multichannel seismic dataset (TIR10 survey), combined with the analysis of morpho-bathymetric and geodetic data, and with numerical modeling. This multidisciplinary and multiscale approach can contribute to unravel the particular role of this region in the context of a stepwise migrating subduction system and provides new constrains for the study of this highly populated area characterized by severe seismic and tsunamigenic hazard.

Fold-and-thrust belts (FTBs) are fundamental geological structures whose spatio-temporal evolution can be reconstructed using s-t graphs that integrate thrust positions and timing to trace sequences of activation and reactivation. However, accurately constraining the timing of thrusting events remains difficult due to methodological uncertainties and inconsistencies among different dating techniques. To address these challenges and offer a refined view of FTB evolution, we compile and integrate time constraints from stratigraphic, thermochronological, and radiometric data across ten FTBs that span diverse geodynamic contexts, including the Rocky Mountains, Idaho-Montana Belt, Sevier Belt, Mexican Fold Belt, and Central Andes in the Cordilleran orogen, and Apennines, Southern Pyrenees, Jura Mountains, Southern Alps, and Himalayas in the Alpine-Himalayan orogen. We assess the strengths and limitations of each method: stratigraphy provides broad but often imprecise age constraints; radiometric dating yields precise yet spatially and temporally sparse data; thermochronology offers insights into vertical displacements linked to thrusting. By constructing and comparing s-t graphs, we identify consistent thrusting patterns across regions. FTBs display a piggy-back propagation style characterized by long-lasting, partially overlapping activity of multiple thrusts. These observations support a revised piggy-back model that incorporates prolonged, synchronous thrust activity within a generally forward-propagating system.

Fault zones in carbonate rocks exhibit distinct microstructural fabrics that develop different microstructures with increasing deformation, going from the outer zone towards the fault core. These fabrics can be effectively characterized using X-ray micro-computed tomography (XR mu CT), a powerful imaging technique that supports a wide range of analyses, from morphometric measurements (e.g., pore size distribution, fractures orientation) to digital rock physics (i.e., virtual experiments on 3D volumes). However, the need for an automated, user-independent tool to classify these microstructures is crucial for large-scale studies. Furthermore, a fully quantitative classification of fault rock fabrics provides valuable insights into the extent and nature of deformation within these rocks. In this study, we present a deep learning-based supervised neural network designed to automate the classification of fault rock microstructures. This system offers rapid, quantitative, and scalable analysis of XR mu CT data, facilitating the identification and classification of fabrics of brittle fault limestone rocks with high precision. The network was trained and validated on purpose collected datasets representing specific fabrics, then it was successfully used on different limestone fault rocks collected from the same area or obtained from the literature. The results show that the software can reliably classify fault rock fabrics affected by brittle deformation into three primary categories, each representing a distinct stage of deformation: fractured limestone, breccia, and cataclasite. The network assigns identification probabilities to each image, which can then be visualized in a ternary diagram for intuitive comparison and interpretation. This classification system streamlines fabric analysis and provides a quantitative measure of the degree of deformation within the rock. This automated classification tool paves the way for advanced studies on the anisotropic properties of fault rocks, enabling high-throughput analysis and enhancing our understanding of fault zone mechanics.

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.

The Gran Sasso range in central Italy is the icon of the Apennines, forming the mountain front of the central Apennines. The range consists of Meso-Cenozoic carbonates overthrust onto Messinian foredeep deposits along the Gran Sasso thrust. Despite its geological relevance, the age of thrusting, especially its end, is uncertain. Such age relies on speculative dating of the Rigopiano conglomerate, the youngest growth strata recording the activity of the Gran Sasso thrust, widely believed to be Early Pliocene in age. However, the reliability of this age attribution is low, being based on the supposed occurrence of marine foraminifera, of which there is no publicly available documentation. We reassess the age, depositional environment, and structural significance of the syn-kinematic Rigopiano conglomerate. Our data indicate a Late Pliocene to Early Pleistocene age and a continental depositional environment, younging the end of the Gran Sasso thrust activity. This revised age significantly increases the inferred duration of thrusting and points to a coeval activity with the more external thrusts in its footwall.