Consorzio Interuniversitario Nazionale per la Bio-Oncologia

High-resolution microearthquake data provide a powerful window into active fault architecture from depth to surface in slowly deforming regions with sparse instrumental seismicity. We integrate microseismic clusters from enhanced catalogs with detailed structural mapping to reconstruct the 3D geometry of seismogenic extensional faults in the Latium-Abruzzi sector of central Italy. Investigated earthquake clusters align geometrically and kinematically with known and newly mapped normal faults showing evidence of Late Quaternary activity. The 3D model depicts a set of SSW-dipping, non-planar faults with an average dip of ∼55° (Sora, San Donato Val di Comino, Villavallelonga, and Pescasseroli). Their cut-off depths deepen NNE-ward, from ∼7 to ∼14 km, suggesting an underlying basal discontinuity dipping∼30-35°. Microseismic patches at the roots of these faults are mostly elongated along dip rather than along strike. This unusual geometry suggests a stress release pattern governed by iso-oriented anisotropic roughness and corrugations on the basal discontinuity, which may focus upward fluid migration and trigger earthquakes along hangingwall splays. Stress inversion reveals a persistent NE–SW tensional stress field consistent across geological and instrumental timescales. An empirical magnitude-area relationship, accounting for both epistemic uncertainty in scaling laws and areal variability of fault surfaces, yields maximum magnitudes between 6.0 and 6.5, consistent with the regional seismotectonic framework. These findings provide new constraints on fault connectivity, stress distribution, and fluid-fault interactions, and help identifying potentially seismogenic sources that may remain unrecognized when geological and seismic data are considered separately. • Microseismic clusters illuminate 3D geometry of Apennine extensional faults • Surface faults linked to deep clusters via integrated field data and 3D modeling • Fault roots dip SSW and sole into a ∼30–35° NNE-dipping extensional detachment • Stress inversion reveals stable NE–SW extensional field across time scales • Findings reveal hidden seismogenic faults and fluid-driven seismic triggering

<strong class="journal-contentHeaderColor">Abstract.</strong> Building a geological model in offshore areas is a complex task, due to the obvious absence of outcrops and thus the inaccessibility to the study site. The integration of key seismic reflection and borehole data is therefore fundamental, even if only available as legacy data on paper hard copy and/or characterized by an apparent low quality. However, such data are often the only ones available, and can still provide a high amount of detailed information for building a reliable geological model to compare and discuss with seismicity distribution in active areas. In this work, legacy seismic reflection profiles calibrated with boreholes are used to propose a new geological model of the frontal part of the Northern Apennines area struck by the 2022 Fano-Pesaro Mw 5.5 earthquake sequence (Adriatic Sea, Italy). The observed tectonic structures are originated by multiple d&eacute;collements located at different depths and show a strong relationship between the faulting depth and the anticlines wavelength. Two structures, namely Pesaro and Cornelia anticlines, are interpreted as related to deep-seated thrusts, showing an en-echelon arrangement and thin-skinned deformation. A smaller wavelength structure, namely Tamara antiform, is interpreted to be related to shallow-seated imbricated fore-verging thrusts in the forelimb of the Pesaro anticline. We highlight the importance of constructing a well-constrained geological model by integrating legacy geological and geophysical data, aimed at offshore seismotectonic studies as well as at industrial applications, particularly in the context of energy transition.

Mount Etna, one of Europe's most active volcanoes, has experienced a variety of eruption settings throughout its history, including summit, flank, and eccentric eruptions. In this study, we provide a detailed analysis of the structures formed during the 1947 eruption, which occurred along the NE Rift, drawing on historical accounts, archival images, and contemporary field and drone data. Photogrammetric processing of 1932 and 1954 historical aerial photos enabled us to identify and map the structures formed before and during the eruption, in order to focus the effects of the direction of the dyke propagation, and of pre-existing fractures on the 1947 deformation pattern. Several data collected through recent field missions allowed us to classify the structures into different types including extensional fractures, normal faults, and eruptive fissures, and to determine their kinematics (pure extensional, right-lateral component, and left-lateral component). We also extracted information on the structures' length, azimuth, vertical offset, vectors and opening amount, to characterize the surface deformations resulting from the magmatic event. Furthermore, we reconstructed a detailed chronology of the eruption's day-by-day development based on available historical data. This information allowed us to characterize the event as a lateral propagation of magma along a N-S to NE-SW-striking dyke. This produced the formation of various structures, with different geometry and deformation amount. In particular, our reconstruction of the fault-slip profiles obtained at both sides of multiple grabens, show that fault scarps taper towards NE. This is consistent with the assumption that lateral dyke propagation can induce the formation of normal faults with asymmetric slip profiles.

Following the abrupt geochemical and geophysical variations that occurred on the island of Vulcano in September 2021, the search for previous multidisciplinary data on decades-long time spans became necessary to contextualize the newly recorded anomalous variations, which represented a serious threat for the local population. Our analyses of ‘vintage’ reports, old documents and analogue seismograms, broaden our understanding of crustal seismic activity. The results unravel the predominant role of Vulcano’s hydrothermal system with respect to tectonic processes in the generation of seismicity in the analyzed sector. Earthquakes were generally located offshore and achieved a maximum M4.6. A 2D strain release map and DBSCAN application highlight seismogenic volumes to the NW, SW and E offshore of the island and trending NNW-SSE inshore, in agreement with structural patterns. Two major volcano unrests in 1985 and 1988 had seismicity mostly confined to the island. In comparison, the longer duration and typology of seismic signals recorded between 2021 and 2022 make this latest episode peculiar in the context of Vulcano’s past seismic activity.

In this work, we have integrated field data and numerical models to characterise a unique dyke-induced graben system, exposed both in section and plan view, with an unexpected asymmetric fault geometry. This volcanotectonic feature is related to the 1971 eruption of Mt. Etna (southern Italy) and is located near the northern wall of the Valle del Bove, a huge depression carved into the eastern flank of the edifice. A new structural map and quantitative data were obtained from the analysis of aerial stereophotos collected before the onset of the 1971 eruption and after, high-resolution drone-derived models and field surveys carried out in the summer of 2022. In plan view, the graben is 2-km-long and its width ranges 27–143 m from the bottom to the upper part of the section view, with about 82 m of difference in elevation from top to bottom. Graben faults clearly show an asymmetric setting in terms of attitude, with one fault that dips 70° to the south, and the other one that dips 50° to the north. Vertical offset values are greater at higher elevations. We also ran a set of numerical models, aimed at investigating the distribution and orientation of stresses around the inferred dyke tip and in the host rock. The comparison between field data and numerical models suggests a key role of the inclined topography, as shown in section view, in determining the orientation of dyke-induced σ1 and σ3 in the host rock. This, in turn, controls the geometry of the graben faults, resulting in the observed asymmetric setting. Additionally, dyke-induced stress concentrations and vertical offset values support the hypothesis of a downward propagation of the graben faults, from the surface down to the dyke tip.

Summary The Po Plain in Northern Italy is characterized by an intricate geological evolution, serving as the shared foreland for the converging Northern Apennines and Southern Alps. Its geological sequence, from the Variscan Basement to Plio-Pleistocene syntectonic cover, has been shaped by inversion events, notably in the Southern Alps since the mid-Eocene. The Northern Apennines front comprises three arcs, the Monferrato Arc, The Emilian Arc and the Ferrara Arc. Recent studies identified thermal anomalies in the Po Plain, prompting a new 3D geological model integration with a thermal model. Methodologically, data from Geothopica and the ViDEPI Project provided a comprehensive analysis of 845 wells, resulting in a 3D thermal model using Leapfrog® Geothermal and SGeMS. Geological features were incorporated using DecisionSpace® Geosciences. The study uncovers correlations between structural highs and positive thermal anomalies. The Emilia and Ferrara Arcs’ differential shortening significantly influences thermal anomaly development. The research underscores the importance of detailed geological models in mature basins, revealing potential for geothermal resources in the Ferrara Arc and Southern Alps, and suggesting ground-source heat pumps for the Emilian Arc’s cooler sedimentary units.

Mt Etna, located on the east coast of Sicily, Italy, is a basaltic stratovolcano with a volcanotectonic evolution of 500 ka, characterized by a wide horse-shoe-shaped depression on its eastern flank, called Valle del Bove. The study area is located near the northern escarpment of this depression, where it is possible to recognize the 1971 eruptive fissure system, generated by the lateral propagation of a feeder dike. The purpose of this research is to thoroughly examine the area affected by dike-induced surface deformation, which is marked by a textbook example of a graben structure produced by dike propagation. Due to the presence of meters-thick, recent pyroclastic deposits covering the study area and the difficult logistics, the main outcrops are inaccessible for classical field data collection. To overcome this limitation, we used the following methodology based on the analysis of photogrammetry-derived models.We first designed a structural map related to the development of the 1971 dike-induced structures, using two sets of historical aerial photos characterized by a 2400 DPI resolution. Particularly, the 20 selected images, equally divided between 1954 and 1983, have been processed using the software Agisoft Metashape to produce two referenced orthomosaics with a resolution of 29 and 19.5 cm/pixel, respectively. By comparing the obtained orthomosaics, we identified and mapped all the normal faults associated with the 1971 dike intrusion. This structural map has been used to organize the subsequent drone surveys, performed by a DJI Phantom 4 Pro equipped with RTK high-precision technology, which allowed us to collect 656 pictures with an overlap and a side lap of 85% and 80% respectively. Afterward, we processed the drone-collected photos by using Structure-from-Motion photogrammetry techniques, so as to obtain a Digital Surface Model (DSM) and a 3D Tiled Model, with a resolution of 11 and 5.48 cm/pixel, respectively. Such models have been used to analyze in detail the graben faults, especially the ones along the Valle del Bove steep wall.The analysis of photogrammetry-derived models over different time windows enabled us to individuate 14 lineaments within the study area, 2 eruptive fissures with a NE-SW strike, and 13 fault scarps associated with the dip-slip faults of the graben. Finally, thanks to the 3D Tiled Model obtained from drone-captured pictures, we were able to quantify the dip direction and dip angles of the graben faults, their vertical offsets, and the graben width related to the elevation.

Dykes (Mode I extension fractures) supply magma from deep reservoirs to the surface and subject to their propagation paths, they can sometimes reach the surface and feed volcanic eruptions. Most of the times they mechanically stall in the heterogeneous crust or deflect through pre-existing fractures forming sills. Although several studies have explored dyking in heterogeneous regimes, the conditions under which dykes propagate in glacial-volcanotectonic regimes remain unclear.Here, we coupled field observations with FEM numerical modelling using the software COMSOL Multiphysics (v5.6) to explore the mechanical and geometrical conditions that promote (or not), dyke-sill propagation in glacial-tectonic conditions. We used as a field example the Stardalur cone sheet-laccolith system, located in the Esja peninsula proximal to the western rift zone. The laccolith is composed of several vertical dykes that bend into sills and form a unique stacked sill &amp;#8216;flower structure&amp;#8217;. We modelled a heterogeneous crustal segment composed of lavas (top) and hyaloclastites (bottom). We then studied the emplacement of a dyke with varied overpressure values (Po = 1-10 MPa) and regional extension (Fe = 0.5-3 MPa) loading conditions at the lava/hyaloclastite contact. In the second stage, we added an ice cap as a body load to explore dyking subject to unloading due to glacier thickness variations (0-1 km).Our results have shown that the presence of the ice cap can affect the dyke-sill propagation and the spatial accumulation of tensile and shear stresses below the cap. The observed field structure in non-glacial regimes has been formed either due to the mechanical contrast (Young&amp;#8217;s modulus) of the studied contact, a compressional regime due to pre-existing dyking or faulting, or finally, high overpressure values (Po &amp;#160;&amp;#8805; 5 MPa). Instead, in a glacial regime, the local extensional stress field below the ice cap encourages the formation of the laccolith when the ice cap becomes thinner (lower vertical loads). Our models can be applied to universal volcanoes related to glacier thickness variation and sill emplacement.