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We document the tectonic and metamorphic evolution of thrust nappes of the eastern island of Elba. The area exposes a natural cross section of the Northern Apennines hinterland, from the metamorphic basement units to the overlying continent- and ocean-derived nappes. We integrated mapping, analysis of structures and microstructures, and the interpretation of drill core logs with lithostratigraphic, metamorphic, and geochronological constraints, producing a novel geological map of eastern Elba (1:5'000 scale). We show that the area experienced polyphase Oligocene - Pliocene contractional tectonics marked by in-sequence and out-of-sequence thrusting accompanied by folding and overprinted by faulting in the Pliocene. Magmatism occurred during contraction with post-magmatic thrusting ultimately coupling HP-LT and LP-HT units. Drill core logs allow for the first time the reconstruction of the N-dipping character of the Zuccale Fault, which represents the youngest (late Miocene - early Pliocene) large-scale structure in the area.

Various methods have been proposed in the literature to predict the rainfall conditions that are likely to trigger landslides in a given area. Most of these methods, however, only consider the rainfall events that resulted in landslides and provide deterministic thresholds with a single possible output (landslide or no‐landslide) for a given input (rainfall conditions). Such a deterministic view is not always suited to landslides. Slope stability, in fact, is not ruled by rainfall alone and failure conditions are commonly achieved with a combination of numerous relevant factors. When different outputs (landslide or no‐landslide) can be obtained for the same input a probabilistic approach is preferable. In this work we propose a new method for evaluating rainfall thresholds based on Bayesian probability. The method is simple, statistically rigorous, and returns a value of landslide probability (from 0 to 1) for each combination of the selected rainfall variables. The proposed approach was applied to the Emilia‐Romagna Region of Italy taking advantage of the historical landslide archive, which includes more than 4000 events for which the date of occurrence is known with daily accuracy. The results show that landsliding in the study area is strongly related to rainfall event parameters (duration, intensity, total rainfall) while antecedent rainfall seems to be less important. The distribution of landslide probability in the rainfall duration‐intensity shows an abrupt increase at certain duration‐intensity values which indicates a radical change of state of the system and suggests the existence of a real physical threshold. Key Points A probabilistic approach is needed to evaluate landslide rainfall thresholds Bayes theorem is suited to this purpose Landslide probability is strongly related to the event rainfall

Several Cyprus-type volcanogenic massive sulphide (VMS) deposits occur in the Jurassic ophiolitic series of the Northern Apennines. Stratabound, stratiform and stockwork deposits were formed in the western limb of the Neotethys (Ligurian Ocean) and are observed today in basalt, gabbro and serpentinised peridotite host rocks. The studied stockwork deposit at Boccassuolo occurs in basalt and basalt breccia. Detailed petrography, fluid inclusion study, Raman spectroscopy analyses and chlorite thermometry calculations were used to determine the P, T, X conditions of the fluid circulation system. The veins contain three quartz generations, calcite, chlorite, epidote and sericite as gangue minerals and pyrite, chalcopyrite, sphalerite, pyrrhotite and galena as ore minerals. Based on the fluid inclusion study, the earlier defined three vein types (1., 2. and 3.) precipitated from the same type of evolving fluid, though at slightly different stratigraphic positions. The determined ranges of temperature (370-60°C), salinity (6.2-11.4 NaCl equiv. wt%), pressure (30-44 MPa) and methane content (average 0.28 mol/kg) suggest an evolved seawater origin for the hydrothermal fluid, modified by fluid-rock interactions and possibly by mixing of magmatic volatiles. The fluid characteristics and the mineralogical observations have proven a slightly distal position in relation to the centre of the fluid flow for all the studied locations, but more central and more distant blocks were also recognised. The temporal evolution of the system developed into a low temperature event, occurring after the main mineral stage of formation, but still within the same overall process.

Trench basins related to an almost entirely subducted oceanic lithosphere are filled by deposits sourced from either the passive continental margin or the accretionary wedge. They also include large-scale submarine landslides often triggered by the inherited rough topography of the subducting plate. This mechanism provides the deposition of material by mass-transport processes from the wedge to the trench, resulting in highly heterogeneous trench sedimentation. The role of the mass-transport deposits in the accretion mechanisms, as well as their influence on seismic behaviour at the plate interface is difficult to assess in the active trenches, because of their limited accessibility. This study reports on a well-preserved fossil trench-fill sequence exposed in the Northern Apennines. A multidisciplinary survey including fieldwork, stratigraphy, biostratigraphy, geochemistry, and zircon provenance, allows reconstructing the anatomy of these deposits. The heterogeneities derived by distinct sediment packages made of mass-transport deposits and deep-sea turbidites reflect a setting with two feeding source areas: the accretionary wedge and the continental margin, respectively. Alongside the roughness of the subducting plate, this deposits association favours coherent underplating processes developed at depth. Such accretion mechanisms, linked to thrust faults at the base of the wedge, can generate both major earthquakes and new mass movements, reinforcing the complex role of trench-fill processes in subduction dynamics.

The 3He/4He ratios measured in 12 CO2‐dominated gas seeps from the Tuscany‐Roman Volcanic Provinces in Italy range between 0.07 and ∼1.6 Ra. Helium and δ13CO2 isotope systematics indicate a dominant crustal source with a variable but significantly lower contribution from the mantle. Low He (3He/4He = 0.6–1.6 Ra) and high Sr (87Sr/86Sr = 0.709514–0.710595) isotope systematics of olivine and pyroxene mantle phenocrysts have been previously interpreted as related to the addition of a crustal signature into a HIMU‐type magma (6.7 ± 0.4 Ra) in the mantle by subduction of continental crust fluids and rocks, thus explaining the much lower 3He/4He ratio compared to typical oceanic subduction zones. This is consistent with the interpretation that CO2 is derived from the decarbonation of limestones at mantle depth, as corroborated by the presence of crustal carbonate melts within the low‐velocity mantle wedge. Here, we explore a model in which crustal contamination expresses the delamination of the continental lithosphere of the (previously subducted) Adria microplate, as previously inferred from geophysics and mechanical modeling. We present coupled thermal and helium isotopic modeling that accounts for radiogenic heat and 4He production in the U, Th, and K‐rich delaminated continental crust and in the variably aged (depending on SCLM age and He residence time) 4He‐rich subcontinental lithospheric mantle. Our models support a delamination tectonic scenario in which the unusually low 3He/4He values and high heat flow data are reproduced by introducing a 15–20 km—thick continental crust into the mantle.

: The measurement of landslide superficial displacement often represents the most effective method for defining its behavior, allowing one to observe the relationship with triggering factors and to assess the effectiveness of the mitigation measures. Persistent Scatterer Interferometry (PSI) represents a powerful tool to measure landslide displacement, as it offers a synoptic view that can be repeated at different time intervals and at various scales. In many cases, PSI data are integrated with in situ monitoring instrumentation, since the joint use of satellite and ground-based data facilitates the geological interpretation of a landslide and allows a better understanding of landslide geometry and kinematics. In this work, PSI interferometry and conventional ground-based monitoring techniques have been used to characterize and to monitor the Santo Stefano d’Aveto landslide located in the Northern Apennines, Italy. This landslide can be defined as an earth rotational slide. PSI analysis has contributed to a more in-depth investigation of the phenomenon. In particular, PSI measurements have allowed better redefining of the boundaries of the landslide and the state of activity, while the time series analysis has permitted better understanding of the deformation pattern and its relation with the causes of the landslide itself. The integration of ground-based monitoring data and PSI data have provided sound results for landslide characterization. The punctual information deriving from inclinometers can help in defining the actual location of the sliding surface and the involved volumes, while the measuring of pore water pressure conditions or water table level can suggest a correlation between the deformation patterns and the triggering factors.

The geological map of Piemonte Region (Italy) is a graphic representation of the geology of the region, grounded on a large geodatabase, that can be also browsed as an interactive scalable map (GeoPiemonte Map) using a WebGIS application. The Map, produced at 1:250,000 scale, is the first original release of the 'GeoPiemonte Map' project. The geological data represented on the map derive from a thorough revision of available geological maps and literature, integrated with unpublished original data. The revision and harmonisation of existing and new data have been based on explicit criteria used for the classification of geologic units and their representation on the Map. These criteria firstly aimed at providing a lithostratigraphic, hierarchic subdivision of Piemonte geologic units and describing them using shared concepts and vocabularies, consistent with IUGS Descriptive Standards for the Geosciences.

Isotropic and anisotropic seismic structures across the Northern Apennines (Italy) subduction zone are imaged using a new method for the analysis of teleseismic receiver functions (RFs). More than 13,000 P‐wave coda of teleseismic records from the 2003–2007 Retreating‐Trench, Extension, and Accretion Tectonics (RETREAT) experiment are used to provide new insights into a peculiar subduction zone between two continental plates that is considered a focal point of Mediterranean evolution. A new methodology for the analysis of receiver functions is developed, which combines both migration and harmonic decomposition of the receiver function data set. The migration technique follows a classical “Common Conversion Point” scheme and helps to focus on a crucial depth range (20–70 km) where the mantle wedge develops. Harmonic decomposition of a receiver function data set is a novel and less explored approach to the analysis of P‐to‐S converted phases. The separation of the back‐azimuth harmonics is achieved through a numerical regression of the stacked radial and transverse receiver functions from which we obtain independent constraints on both isotropic and anisotropic seismic structures. The application of our method to the RETREAT data set succeeds both in confirming previous knowledge about seismic structure in the area and in highlighting new structures beneath the Northern Apennines chain, where previous studies failed to clearly retrieve the geometry of the subducted interfaces. We present our results in closely spaced profiles across and along the Northern Apennines chain to highlight the convergence of the Tyrrhenian and the Adriatic microplates which differ in their crustal structure where the Adriatic microplate subducts beneath Tuscany and the Tyrrhenian sea. A signature of the dipping Adriatic Moho is clearly observed beneath the Tyrrhenian Moho in a large portion of the forearc region. In the area where the two Mohos overlap, our new analysis reveals the presence of an anisotropic body above the subducted Moho. There is a strong Ps converted phase with anisotropic characteristics from the top of the Adriatic plate to a depth of at least 80 km. Because the Ps conversion occurs much deeper than similar Ps phases in Cascadia and Japan, dehydration of oceanic crust seems unlikely as a causative factor. Rather, the existence of this body trapped between the two interfaces supports the hypothesis of lower crustal delamination in a postsubduction tectonic setting.

Geothermal systems in terrains affected by polyphase deformation have reservoirs with a 3D geometry that is always difficult to predict. In this paper we describe a fossil exhumed geothermal system exposed in eastern Elba Island that developed in a polyphase folded and faulted setting, which can help us to understand how geothermal fluids circulate in geological bodies with inherited structures. Geothermal circulation at Elba allowed the deposition of Fe-ore deposits (haematite/magnetite and pyrite) and altered rock volumes, which represent tracers of the palaeo-fluid flow. Normal and oblique-slip faults dissected a polyphase folded metasiliciclastic succession and produced a secondary permeability in the range of 5 × 10−13 to 5 × 10−16 m2. From the permeable fault zones acting as feeder conduits, geothermal fluids permeated the hydraulically connected metasiliciclastic rock bodies previously deformed by two generations of folds. Geothermal fluids followed the already defined geometry, thus giving rise to apparent folded mineralized levels. Fluid migration into the metasiliciclastic rocks was possible due to their chemical aggression, which favoured the dissolution and reprecipitation of quartz, and Fe-oxide and sulphide deposition. Renewed fluids maintained their chemical properties (pH value and temperature, mostly). This conclusion provides inputs for reconstructing geothermal conceptual models and evaluating the geothermal potentiality of exploitable areas developing in similar geological settings.

This research focuses on the essential task of defining rainfall thresholds in regions with complex geological features, specifically at a regional scale. It examines a variety of methodologies, from traditional empirical-statistical methods to cutting-edge machine learning (ML) techniques, for establishing these thresholds. The Emilia-Romagna region in Italy, known for its intricate geological structure and prevalence of weak rocks that often lead to large and deep-seated landslides, serves as the study area. The region’s complex interplay between rainfall and landslide incidences poses a significant challenge in accurately determining rainfall thresholds. The effectiveness of ML methods is compared against conventional empirical-statistical approaches, evaluating factors such as prediction accuracy, model complexity, and the interpretability of results for use by regional landslide warning system operators. The findings indicate that machine learning techniques have an edge over traditional methods, yielding higher performance scores and fewer false positives. Nevertheless, these advancements are modest when considering the increased complexity of ML methods and the incorporation of additional rainfall parameters. This underlines the continued need for improvements in data quality and volume. The study stresses the importance of enhancing data collection and analysis techniques, especially in an era where advanced AI tools are increasingly available, to improve the accuracy of predicting rainfall thresholds for effective landslide warning systems.