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Mud volcanoes (MVs) are surface structures typically created by episodic discharge of fluids and solids, often associated to onshore and offshore accretionary prisms on convergent plate boundaries. Detailed investigations of ongoing activity and its associated morphological changes, as well as a better understanding of the temporal evolution of these highly dynamic systems, may improve the estimations of material fluxes from MVs drastically. Until today, approximately 70 individual MVs were discovered in the northern Ionian Sea in the Calabrian Arc (Central Mediterranean Sea), but only a few have been analyzed and described in detail. In this study, new evidence for recent recurring eruptive activity of the ~45 m-high and 1 km-wide Sartori MV situated in the clastic wedge of the Calabrian Arc is presented. High-resolution seafloor mapping as well as sediment temperature, geochemical, and sedimentological data received from two research cruises in 2016 and 2020 are used. Bathymetric and seafloor backscatter data (1 m scale) indicate the presence of two active eruption centers at the flat-topped Sartori MV. Elevated sediment temperature gradients at both eruption centers show that currently heat is transferred to the surface sediments. Pore water analyses indicate that fluids rising below the eruption centers are CH4-rich, Cl--poor, and SO42--free. Stable C and H isotopic compositions of methane suggest that it originates from a mix of primary microbial, secondary microbial, and/or thermogenic sources. A relatively shallow position of the sulfate-methane interface at both eruption centers also indicates the presence of upward fluid migration in recent times. Pore water modeling suggests that seawater has penetrated the surface sediments to a greater extent within the last few years. In contrast, centimeter-thick layers of hemipelagic sediments overlying mud breccia in sediment cores taken from both eruption centers show that no solid material has been ejected in recent times. Sediment core analyses combined with high-resolution seafloor mapping show an absence of rim-passing mudflows over the past ~10 ka. It is concluded that Sartori MV is an episodically active MV from which fluids with a comparatively low flux were released into the bottom water in recent times. [ABSTRACT FROM AUTHOR]

ABSTRACTIn this paper we show data from new detailed geological-structural field surveys, integrated with preliminary photogrammetric analysis, presented in a 1:10,000 scale geological map. The field-based investigations covered an area of about 60-km2, located at the southern termination of the Calabrian Forearc, in NE Sicily (Italy), at the intersection of two key regional-scale fault systems. These are represented by the Peloritani Sole-Thrust, along which the Kabilo-Calabride orogenic edifice overthrusted onto the Apenninic-Maghrebian Chain, and the Mt. Kumeta-Alcantara Line, which played a key role in the post-Oligocene evolution of the Nubia–Eurasia converging margin. The collected data permitted the recognition of a new terrigenous stratigraphic unit, the Malvagna Flysch, and the acquisition of updated structural information useful to better understand the kinematics of the easternmost portion of the Mt. Kumeta-Alcantara Line. The geological map provides new insights for the reconstruction of the geodynamic evolution of this sector of the Calabrian Forearc.

Mud volcanoes (MVs) are surface structures typically created by episodic discharge of fluids and solids, often associated to onshore and offshore accretionary prisms on convergent plate boundaries. Detailed investigations of ongoing activity and its associated morphological changes, as well as a better understanding of the temporal evolution of these highly dynamic systems, may improve the estimations of material fluxes from MVs drastically. Until today, approximately 70 individual MVs were discovered in the northern Ionian Sea in the Calabrian Arc (Central Mediterranean Sea), but only a few have been analyzed and described in detail. In this study, new evidence for recent recurring eruptive activity of the ∼45 m-high and 1 km-wide Sartori MV situated in the clastic wedge of the Calabrian Arc is presented. High-resolution seafloor mapping as well as sediment temperature, geochemical, and sedimentological data received from two research cruises in 2016 and 2020 are used. Bathymetric and seafloor backscatter data (1 m scale) indicate the presence of two active eruption centers at the flat-topped Sartori MV. Elevated sediment temperature gradients at both eruption centers show that currently heat is transferred to the surface sediments. Pore water analyses indicate that fluids rising below the eruption centers are CH4-rich, Cl−-poor, and SO42−-free. Stable C and H isotopic compositions of methane suggest that it originates from a mix of primary microbial, secondary microbial, and/or thermogenic sources. A relatively shallow position of the sulfate–methane interface at both eruption centers also indicates the presence of upward fluid migration in recent times. Pore water modeling suggests that seawater has penetrated the surface sediments to a greater extent within the last few years. In contrast, centimeter-thick layers of hemipelagic sediments overlying mud breccia in sediment cores taken from both eruption centers show that no solid material has been ejected in recent times. Sediment core analyses combined with high-resolution seafloor mapping show an absence of rim-passing mudflows over the past ∼10 ka. It is concluded that Sartori MV is an episodically active MV from which fluids with a comparatively low flux were released into the bottom water in recent times.

Active normal faulting and uplifting, consistent with a WNW-ESE-oriented regional extension, dominate the Quaternary tectonics of the southern Calabrian Arc. The main tectonic structures of this extensional domain are considered to be the source of numerous historical and recent strong earthquakes, among which the 1783 seismic sequence (M 6.5–7) was one of the most destructive earthquakes ever recorded in Southern Italy. Previous works on the seismotectonic of the Calabrian Arc indicate a disagreement on the attitude (E-dipping vs W-dipping) of the main seismogenic sources slicing across southern Calabria, whereby the seismotectonic framework is still debated. Following a multidisciplinary approach, based on morpho-structural and seismological data, the geometry at depth of the most reliable sources (i.e., Cittanova and Serre faults) was first modelled in a 3D environment to retrieve information about their seismic potential. The GNSS data from the permanent stations of RING/RDN and TopNETlive Italy networks have been processed in order to estimate the velocity field affecting this area. Then, data inversion allowed us to document a predominant WNW-ESE active extensional strain orthogonally to the modelled faults, consistent with the regional dynamics. The reliability of the model was tested using empirical relationships and fault response modelling simulation. Furthermore, slip tendency analysis revealed the propensity to slip of the modelled planes by applying a remote stress state derived from the kinematic-structural survey on fault planes.

In this paper we show data from new detailed geological-structural field surveys, integrated with preliminary photogrammetric analysis, presented in a 1:10,000 scale geological map. The field-based investigations covered an area of about 60-km2, located at the southern termination of the Calabrian Forearc, in NE Sicily (Italy), at the intersection of two key regional-scale fault systems. These are represented by the Peloritani Sole-Thrust, along which the Kabilo-Calabride orogenic edifice overthrusted onto the Apenninic-Maghrebian Chain, and the Mt. Kumeta-Alcantara Line, which played a key role in the post-Oligocene evolution of the Nubia–Eurasia converging margin. The collected data permitted the recognition of a new terrigenous stratigraphic unit, the Malvagna Flysch, and the acquisition of updated structural information useful to better understand the kinematics of the easternmost portion of the Mt. Kumeta-Alcantara Line. The geological map provides new insights for the reconstruction of the geodynamic evolution of this sector of the Calabrian Forearc. [ABSTRACT FROM AUTHOR]

In this work, we investigated the landscape response to the recent activity of the faults affecting the Catanzaro Trough, a seismically active structural basin that developed transversally to the Calabrian Arc (Southern Italy) during the Neogene–Quaternary. We carried out a geomorphological and morphometric study of the drainage networks and basins intercepted by the Quaternary faults that were previously mapped through remote and field analyses. The study confirms the occurrence north of the Catanzaro Trough of a WNW–ESE-oriented left-lateral strike-slip fault system (here named the South Sila Piccola Fault System), which accommodates the differential SE-ward migration of the upper crustal sectors of the Calabrian Arc, and of a south-dipping WNW–ESE-oriented oblique fault system (the Lamezia-Catanzaro Fault System), characterized by a predominant normal component of movement. The latter delimits the Catanzaro Trough and accommodates the transition from a strike-slip regime to an extensional regime in the south. Inside the Catanzaro Trough, we detected for the first time a NNE–SSW-trending, WNW-dipping fault system (here named the Caraffa Fault System). This system contributes to accommodate the extension that occurs orthogonally to the southern sector of the Calabrian Arc. The geomorphological and morphometric analysis revealed the recent activity of these fault systems. In particular, the activity of the Caraffa Fault System is evidenced by the differential uplift and tilting of discrete areas inside the basin. Given its location, geometry, and kinematics, the Caraffa Fault System could be responsible for the occurrence of large historical earthquakes. [ABSTRACT FROM AUTHOR]

Probabilistic seismic hazard analysis (PSHA) are performed for routine applications using source models and ground motion prediction equations (GMPEs) recommended by a government agency (e.g., US Geological Survey) or an expert panel (e.g., SHARE project). For important projects, site-specific PSHA involves critical analysis of GMPEs and sources for the application region. We adopt the latter approach for a dam site in Calabria (southern Italy), a high seismic hazard region. Following SHARE convention, we consider faults sources, background zones, and area sources. We identify several problems with assigned maximum magnitudes in the SHARE model for fault and in-slab subduction sources. We add two sources not present in some prior inventories – the crustal Lakes fault and the Calabrian arc subduction interface. Following procedures developed for the Global Earthquake Model, we select GMPEs that are much better constrained in the hazard-controlling range of magnitudes and distances than those typically used in prior Italian applications. Short-period spectral accelerations at the 2475 year return period exceed those from prior SHARE studies by about 10-15%. Despite the site being located in a region with finite faults capable of generating large events, the 2475-year hazard is dominated by source zones that allow for earthquakes directly beneath the site.

Abstract Identification of catastrophic events recorded as resedimented deep marine deposits can be challenging because of multiple possible triggering mechanisms. This study investigates seismo‐turbidites (STs) deposited in the Ionian Sea as a consequence of major historical earthquakes related to the Calabrian Arc subduction system. Taking advantage of the available sedimentological reconstructions, we focused our analysis on high‐resolution X‐ray fluorescence core scanner (XRF‐CS), organic carbon and isotopic data to define geochemical signatures characterizing the ST units. The relationships between geochemical and sedimentological proxies were statistically tested using Pearson correlation and principal component analysis (PCA). Up to ∼78% of the total variance in the data set can be reduced to three principal components which identified four elemental ratio groups associated to the degree of terrestrial/coastal influence in each major depositional unit (i.e., pelagic, ST sandy stacked units, homogenites, tsunamite‐seiche laminites, and tsunamite backwash). The sample score results were evaluated together with organic carbon data in order to assess geochemical variability throughout the composite turbidite structure in different basins settings. The basal parts of the ST contain coarse‐grained sediment stacks whose sources can be traced back and sedimentary processes (surficial sediment erosion/massive slope failures) can be defined using geochemical data. The topmost parts of the STs exhibit a mixed compositional character suggesting basin‐wide processes such as seiche oscillations and tsunami wave erosion/backwashing. The application of selected XRF‐CS based elemental ratios as proxies in paleoseismological studies can help reconstruct the seismic history of a continental margin.

Seismological data recorded in the Ionian Sea by a network of seven Ocean Bottom Seismometers (OBSs) during the 2017–2018 SEISMOFAULTS experiment provides a close-up view of seismogenic structures that are potential sources of medium-high magnitude earthquakes. The high-quality signal-to-noise ratio waveforms are observed for earthquakes at different scales: teleseismic, regional, and local earthquakes as well as single station earthquakes and small crack events. In this work, we focus on two different types of recording: 1) local earthquakes and 2) Short Duration Events (SDE) associated to micro-fracturing processes. During the SEISMOFAULTS experiment, 133 local earthquakes were recorded by both OBSs and land stations (local magnitude ranging between 0.9 and 3.8), while a group of local earthquakes (76), due to their low magnitude, were recorded only by the OBS network. We relocated 133 earthquakes by integrating onshore and offshore travel times and obtaining a significant improvement in accuracy, particularly for the offshore events. Moreover, the higher signal-to-noise ratio of the OBS network revealed a significant seismicity not detected onshore, which shed new light on the location and kinematics of seismogenic structures in the Calabrian Arc accretionary prism and associated to the subduction of the Ionian lithosphere beneath the Apennines. Other signals recorded only by the OBS network include a high number of Short Duration Events (SDE). The different waveforms of SDEs at two groups of OBSs and the close correlation between the occurrence of events recorded at single stations and SDEs suggest an endogenous fluid venting from mud volcanoes and active fault traces. Results from the analysis of seismological data collected during the SEISMOFAULTS experiment confirm the necessity and potential of marine studies with OBSs, particularly in those geologically active areas of the Mediterranean Sea prone to high seismic risk.

Identification of catastrophic events recorded as resedimented deep marine deposits can be challenging because of multiple possible triggering mechanisms. This study investigates seismo‐turbidites (STs) deposited in the Ionian Sea as a consequence of major historical earthquakes related to the Calabrian Arc subduction system. Taking advantage of the available sedimentological reconstructions, we focused our analysis on high‐resolution X‐ray fluorescence core scanner (XRF‐CS), organic carbon and isotopic data to define geochemical signatures characterizing the ST units. The relationships between geochemical and sedimentological proxies were statistically tested using Pearson correlation and principal component analysis (PCA). Up to ∼78% of the total variance in the data set can be reduced to three principal components which identified four elemental ratio groups associated to the degree of terrestrial/coastal influence in each major depositional unit (i.e., pelagic, ST sandy stacked units, homogenites, tsunamite‐seiche laminites, and tsunamite backwash). The sample score results were evaluated together with organic carbon data in order to assess geochemical variability throughout the composite turbidite structure in different basins settings. The basal parts of the ST contain coarse‐grained sediment stacks whose sources can be traced back and sedimentary processes (surficial sediment erosion/massive slope failures) can be defined using geochemical data. The topmost parts of the STs exhibit a mixed compositional character suggesting basin‐wide processes such as seiche oscillations and tsunami wave erosion/backwashing. The application of selected XRF‐CS based elemental ratios as proxies in paleoseismological studies can help reconstruct the seismic history of a continental margin. Plain Language Summary: Submarine paleoseismology is a widely applied method to reconstruct seismicity back in time in tectonically active regions. The Calabrian Arc in the Ionian Sea is a subduction system related to the convergence between Africa and Eurasia plates which produces uplifting coastal mountains, enhances discharge of sediments on the continental shelf and induces the frequent occurrence of earthquakes. Seismic shaking is often associated with submarine slope failures, tsunamis and deposition of seismo‐turbidites which represent more than 90% of total sedimentation in the deep Mediterranean basins. We analyzed physical and geochemical data of sediment samples through a statistical approach to identify elemental ratio groups bringing information on the difference between the interseismic and co‐seismic sedimentary processes, as well as the degree of terrestrial/coastal influence in marine sediments. The proposed statistical approach can be used for sediment characterization, in absence of other analytical data, providing fast information on sedimentary processes and ultimately on the seismic history of the continental margin. Key Points: Analysis of elemental, organic carbon, and isotopic data from seismo‐turbidites provides information on source to sink processesStatistical analysis of physical and geochemical variables enhances correlation of earthquake‐triggered depositsThe application of selected geochemical proxies in paleoseismological studies can be very effective in reconstructing past seismicity [ABSTRACT FROM AUTHOR]

In this work, we investigated the landscape response to the recent activity of the faults affecting the Catanzaro Trough, a seismically active structural basin that developed transversally to the Calabrian Arc (Southern Italy) during the Neogene–Quaternary. We carried out a geomorphological and morphometric study of the drainage networks and basins intercepted by the Quaternary faults that were previously mapped through remote and field analyses. The study confirms the occurrence north of the Catanzaro Trough of a WNW–ESE-oriented left-lateral strike-slip fault system (here named the South Sila Piccola Fault System), which accommodates the differential SE-ward migration of the upper crustal sectors of the Calabrian Arc, and of a south-dipping WNW–ESE-oriented oblique fault system (the Lamezia-Catanzaro Fault System), characterized by a predominant normal component of movement. The latter delimits the Catanzaro Trough and accommodates the transition from a strike-slip regime to an extensional regime in the south. Inside the Catanzaro Trough, we detected for the first time a NNE–SSW-trending, WNW-dipping fault system (here named the Caraffa Fault System). This system contributes to accommodate the extension that occurs orthogonally to the southern sector of the Calabrian Arc. The geomorphological and morphometric analysis revealed the recent activity of these fault systems. In particular, the activity of the Caraffa Fault System is evidenced by the differential uplift and tilting of discrete areas inside the basin. Given its location, geometry, and kinematics, the Caraffa Fault System could be responsible for the occurrence of large historical earthquakes.

The Calabrian Arc subduction, southern Italy, is a critical structural element in the geodynamic evolution of the central Mediterranean basin. It is a narrow, northwest-dipping slab bordered to the southwest by the Alfeo Fault System (AFS) and to the northeast by a gradual transition to a collision. We used a dense set of two-dimensional high-penetration (up to 12 s) multichannel seismic reflection profiles to build a three-dimensional model that spans the AFS for over 180 km of its length. We find that the AFS is made up of four deep-seated major blind segments that cut through the lower plate, offset the subduction interface, and only partially propagate upward across the accretionary wedge in the upper plate. These faults evolve with a scissor-like mechanism (mode III of rupture propagation). The shallow part of the accretionary wedge is affected by secondary deformation features well aligned with the AFS at depth but also mechanically decoupled from it. Despite the decoupling, the syn-tectonic Pliocene-Holocene deposits that fill in the accommodation space generated by the AFS activity at depth, constrain the age of inception of the AFS and allows us to estimate its throw and propagation rates. The maximum throw value is 6,000 m in the NW sector and decreases to the SE. Considering the age of faulting, the fault throw rate decreases accordingly from 2.31 mm/yr to 1 mm/yr. The propagation rate decreases from 62 mm/yr to 15 mm/yr during the Pliocene-Pleistocene, suggesting that also the Calabrian subduction process should have slowed down accordingly. The detailed spatial and temporal reconstruction of this type of faults can reveal necessary information about the evolution of subduction systems.

Using seismic reflection profiles and bathymetric data, we analyzed the stratigraphy and tectonics of the Paola Basin, providing information on the dynamic of the forearc of the Tyrrhenian‐Ionian subduction system. The Paola Basin is a NNW‐SSE trending syncline, bounded by the Coastal Chain to the east and the Paola Anticline to the west. It hosts up to 5.2 km thick Plio‐Quaternary deposits, most of them supplied from Apenninic/Sila entry points and transported by longshore currents. The total subsidence reaches a value of ∼5 km. The sedimentary load varies from 60% to 75% of the total subsidence. The Pliocene to Lower Pleistocene sedimentary infill of the syncline displays a strata growth geometry consistent with a continuous rotation of the eastern limb of the Paola Anticline. Crustal folding can explain both the tectonic subsidence of the Paola Basin and the uplift of the Paola Anticline. To the east of the basin, Late Pliocene to Early Pleistocene growth of the central sector of the Coastal Chain led to the definition of the Paola and Crati basins, previously connected in a larger proto basin. The trench‐parallel component of the plate movement was accommodated by a strike‐slip zone, with associated releasing and restraining bends coinciding with the Paola Anticline. The bathymetric expression of the strike‐slip zone consists of structural highs and depressions that overall form the Paola Ridge. Since the Middle Pleistocene, the growth of the Paola Anticline and Paola Basin came to an end and extensional tectonics controlled the evolution of the forearc region. Key Points: Crustal folding exerts a first‐order control on basin formation and tectonic subsidence of the Paola BasinSedimentary infill of the Paola Basin shows a strata growth geometry consistent with a folding by limb rotation of the Paola AnticlineThe Paola Basin is limited westward by a strike‐slip fault zone that accommodates the trench‐parallel component of the upper plate motion [ABSTRACT FROM AUTHOR]

A multidisciplinary work integrating structural, geodetic and seismological data was performed in the Catanzaro Trough (central Calabria, Italy) to define the seismotectonic setting of this area. The Catanzaro Trough is a structural depression transversal to the Calabrian Arc, lying in-between two longitudinal grabens: the Crati Basin to the north and the Mesima Basin to the south. The investigated area experienced some of the strongest historical earthquakes of Italy, whose seismogenic sources are still not well defined. We investigated and mapped the major WSW–ENE to WNW–ESE trending normal-oblique Lamezia-Catanzaro Fault System, bounding to the north the Catanzaro Trough. Morphotectonic data reveal that some fault segments have recently been reactivated since they have displaced upper Pleistocene deposits showing typical geomorphic features associated with active normal fault scarps such as triangular and trapezoidal facets, and displaced alluvial fans. The analysis of instrumental seismicity indicates that some clusters of earthquakes have nucleated on the Lamezia-Catanzaro Fault System. In addition, focal mechanisms indicate the prevalence of left-lateral kinematics on E–W roughly oriented fault plains. GPS data confirm that slow left-lateral motion occurs along this fault system. Minor north-dipping normal faults were also mapped in the southern side of the Catanzaro Trough. They show eroded fault scarps along which weak seismic activity and negligible geodetic motion occur. Our study highlights that the Catanzaro Trough is a poliphased Plio-Quaternary extensional basin developed early as a half-graben in the frame of the tear-faulting occurring at the northern edge of the subducting Ionian slab. In this context, the strike-slip motion contributes to the longitudinal segmentation of the Calabrian Arc. In addition, the high number of seismic events evidenced by the instrumental seismicity, the macroseismic intensity distribution of the historical earthquakes and the scaling laws relating to earthquakes and seismogenic faults support the hypothesis that the Lamezia-Catanzaro Fault System may have been responsible for the historical earthquakes since it is capable of triggering earthquakes with magnitude up to 6.9.

Along the northern Ionian margin of Calabria, three Neogene basins comprise wedge-top depozones containing syntectonic deposits which cover the frontal part of the fold-thrust belt. One of the best exposed onshore allochthonous siliciclastic successions is represented by the Cariati Nappe, cropping out in the Cirò Basin. Field geological mapping and aerial interpretations were used to characterize the stratigraphy and tectonics of the area between the Arso Stream and Nicà River catchments (about 170 km2), including a Paleozoic metamorphic basement complex unconformably overlain by Upper Oligocene to Quaternary siliciclastic deposits and minor carbonates. This paper presents a 1:25,000 scale map of the Ionian study area, providing lithological and structural data towards reconstructing its tectono-sedimentary evolution.

Volcanic‐intrusive complexes often formed along lateral slab edges as a consequence of subduction‐induced mantle flow. We investigate this process in the southern Tyrrhenian Sea by integrating multibeam bathymetry, seismic‐reflection data, regional magnetic anomalies data, and seismological data. The interpretation of the data highlights the presence of magmatic intrusions that locally reach the seafloor forming volcanic edifices. Chimneys, lava flows, and laccoliths are observed beneath and surrounding the volcanoes. The emplacement and cooling of the magma occurred during the Brunhes Chron. The volcanoes are not active even if the hydrothermal activity occurs. The volcanic‐intrusive complex can be subdivided in a western domain (Diamante and Enotrio seamounts) where strike‐slip transpressional faults deform the volcanic edifices and an eastern domain (Ovidio volcanic seamounts) characterized by flat‐topped volcanic edifices. The flat‐topped morphology is the result of the interplay between volcanism, erosion, sedimentation, and sea‐level change. The Ovidio volcanic seamounts formed in an area that experienced at least 60 m of subsidence. Magnetic signatures over the northern side of the Ovidio and Diamante seamounts highlight the presence of a deep‐rooted, magnetized feeding system remnant. Volcanic edifices extend above a magma feeding system, characterized by low Vp/Vs ratios. The Diamante‐Enotrio‐Ovidio volcanic‐intrusive complex formed as a consequence of the ascent of subduction‐induced mantle flow originated in the northern‐western edge of the retreating Ionian slab. We speculate that the magma ascent was controlled by a strike‐slip deformation belt, which accommodated the bulk of the shear strain resulting from the formation of a roughly E‐W trending, Subduction‐Transform Edges Propagator fault. Key Points: An unknown volcanic‐intrusive complex is identified in an area located about 15 km off the Tyrrhenian coast of northern CalabriaThe volcanic edifices formed in correspondence of a shallower crustal volume characterized by low Vp/Vs ratiosThe volcanic‐intrusive complex is originated by the decompression melting of mantle material at the northern edge of the Ionian slab [ABSTRACT FROM AUTHOR]

The south-western edge of the Calabrian Arc in southern Italy has been investigated throughout a joint analysis of field, marine and geophysical data which provided constraints on the fault pattern and on the seismotectonic potential. The study was focused on a poorly known sector of a larger belt of seismically active faults slicing across the NE corner of Sicily, the so-called Tindari Fault System. Our data pointed out that the investigated area, including the mainland and the Ionian offshore, is deformed by oblique faulting with a general NW-SE tectonic trend. Earthquake distribution and seismic profiles pointed out active deformation in the offshore while the mainland is characterized by the occurrence of a NW-SE oriented, >20 km-long, structural belt. However, scarce seismicity has been recorded in the last 30 years alongside this tectonic structure, accounting for a possible silent segment of the larger fault system. Tomographic images revealed that the Moho discontinuity is deformed by a NE-dipping lithospheric tectonic structure which has been here retained the main mode of deformation and responsible for coseismic displacement in the area. As a whole, field and geophysical data agree with a general NW-SE trend segmented pattern of recent/active faults that have the potentiality of generating magnitude 6.5–7 earthquakes. • We studied a poorly known sector of the Tindari Fault System, an active faults belt slicing across the NE Sicily. • Data highlight that the studied sector has been deformed by oblique NW-SE trending faulting. • Earthquake distribution and seismic profiling evidenced active deformation. • A seismic gap in the area has been attributed to a silent segment of the analysed fault system • Lithospheric deformation is expressed by a large transtensional fault which deforms the Moho [ABSTRACT FROM AUTHOR]

The tectonics and geodynamics of the Calabria region are presented in this study. These are inferred by precise computation of Global Navigation Satellite Systems (GNSS) permanent station velocities in a stable Eurasian reference framework. This allowed computation of the coordinates, variance and covariance matrixes, and horizontal and vertical velocities of the 36 permanent sites analyzed, together with the strain rates, and using different techniques. Interesting geodynamic phenomena are presented, including compressional, and deformational fields in the Tyrrhenian coastal sites of Calabria, extensional trends of the Ionian coastal sites, and sliding movement of the Crotone Basin. Conversely, on the northern Tyrrhenian side of the network near the Cilento Park area, the usual extensional tectonic perpendicular to the Apennine chain is observed. The large-scale pattern of the GNSS height velocities is shown, which is characterized by general interesting geodynamic vertical effects that appear to be due to geophysical movement and anthropic activity. Finally, the strain-rate fields computed through three different techniques are compared.

Abstract: Extracting tectonic signals from the landscape is an important challenge for constraining the style and rate of deformation associated with active faults, especially where their displacement history cannot be independently determined. Based on previous paleoseismological data coupled with new geomorphological field work and 14C dating of geomorphic markers, we analysed the geomorphic signal of the along‐strike differential throw of the Cittanova Fault in southern Calabria (Italy), the recent activity of which is already well documented and constrained. Through DTM‐derived stream power law parameters (SL and χ), we provide evidence of drainage network disequilibrium and reorganization in response to fault growth and deformation style. Furthermore, a methodological test of the reliability of the χ metric as a proxy for the differential throw along the strike of active normal faults provided good preliminary results, consistent with a strong inverse linear correlation with fault throw. Copyright © 2018 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Tectonic forcing causes the relief-building of mountain chains and enforces the surficial processes in a persistent dismantling of rock volumes, continuously modelling Earth's surface. Actually, we observe transient landscapes that have temporarily recorded tectonic forcing as a codified signal. The Late Quaternary tectonic evolution of northeastern Sicily, located along the Nubia-Eurasia plate boundary at the southern termination of the Calabrian arc, has been dominated by intense Plio-Pleistocene dynamics that severely modified the Late Miocene landscape. The present work aims to investigate geomorphically northeastern Sicily, essentially focusing on the hypsometric and relief analyses of the region in order to define how the topography responds to the post-Pliocene tectonic deformation. We apply different relief morphometric indices (Hypsometric Integral, Topographic Relief and Topographic Dissection) measured for each differently sized moving window, and we use different swath topographic profiles as well. Our analysis evidences differential morphological responses between distinct morphotectonic domains of the studied area, led by the combination of earlier morphological background and Late Quaternary tectonic deformation stages of the region. In addition, in the context of a constant and uniform tectonic uplift, the results define the general space- and time-relating pathways of the landscape geomorphic metrics. This enables us to bring out the controls of the vertical scale of landscape on hypsometry, exploring their mutual relationships. Finally, we reconstruct the Late Quaternary morphotectonic evolution of the region, defining the role played by the main tectonic alignments on the present geomorphic setting. [ABSTRACT FROM AUTHOR]

Between June 2011 and September 2013, the Nebrodi Mountains region was affected by a seismic swarm consisting of > 2700 events with local magnitude 1.3 ≤ M L ≤ 4.6 and located in the 5–9 km depth interval. The seismic swarm defines a seismogenetic volume elongated along the E-W direction and encompasses the NW-SE-oriented tectonic boundary between the Calabrian arc (north-eastward) and the Sicilide units (south-westward). By exploring the recent tectonic deformation and the seismic behavior of the region, this study aims at providing additional constraints on the seismogenetic faults at the southern termination of the Calabrian arc. Waveform similarities analysis allowed observing that ~ 45% of the whole dataset can be grouped into six different families of seismic events. Earthquake multiplet families are mainly located in the eastern part of the seismogenetic volume. We suggest that such a feature is responsive to the lateral lithological variations as highlighted by geology (at the surface) and P-wave seismic tomography (at depth of 10 km). Stress tensor inversions performed on FPSs indicate that the investigated region is currently subject to a nearly biaxial stress state in an extensional regime, such that crustal stretching occurs along both NW-SE and NE-SW directions. Accordingly, mesoscale fault geometries and kinematics analyses evidence that a younger normal faulting stress regime led to a tectonic negative inversion by replacing the pre-existing strike-slip one. Based on our results and findings reported in recent literature, we refer such a crustal stretching to mantle upwelling process (as evidenced by diffuse mantle-derived gas emissions) coupled with a tectonic uplift involving north-eastern Sicily since Middle Pleistocene. Moreover, seismic swarms striking the region would be related to the migration of mantle and sub-crustal fluids toward the surface along the complex network of tectonic structures cutting the crust and acting as pathways. [ABSTRACT FROM AUTHOR]

[Display omitted] • Offshore record of high-energy sedimentary events triggered by seismic activity. • Megaturbidites related to far field tsunamigenic earthquakes in the Hellenic Arc. • Megaturbidites triggered by Calabrian Arc subduction-type events. • Recurrence time of large plate-interface earthquakes is 2–3 ka. • The last subduction-thrust event dates back to 2.9 ka and this requires an update of the seismic hazard assessment in the region. The Calabrian Arc subduction-rollback system hosts seismogenic faults capable of generating earthquakes exceeding magnitude 7. Since earthquakes are the result of long-term geodynamic processes, documenting seismic activity during a sufficiently long time interval is of fundamental importance for hazard scenarios. Instrumental and historical data provide critical information on seismogenesis, but they cover time periods shorter than the recurrence times of large earthquakes, especially in areas with low deformation rates such as Calabria. If onshore paleoseismological studies are fundamental to compile earthquake catalogs, they are sometime affected by the relatively poor continuity of sedimentation in the subaerial environment. In this study we applied the paleoseismological approach to the submarine environment to reconstruct the record of high-energy sedimentary events triggered by seismic activity. We analyzed three gravity cores collected in disconnected sedimentary basins to reconstruct resedimentation processes during the Holocene, integrating inland information for a better assessment of tectonic activity and seismogenesis. Multiproxy analyses of the sedimentary record constrained by radiometric dating allowed reconstructing event stratigraphy and linking resedimented deposits to specific earthquakes. Onshore and offshore data allow to identify large-magnitude earthquakes in the central Calabrian Arc subduction system during the Holocene, with inferred epicenters located either along normal faults onshore and/or related to the slab dynamics. The turbidite record reveals 20 major events during the last 10 ka, with sources including crustal faults in Calabria (i.e. Lakes, Rossano and Cittanova faults). Analyses of sediment samples and high-resolution seismic reflection images allowed identification of different types of resedimented deposits during the last 30–50 ka. The basin-wide occurrence of three megaturbidites/homogenites suggests they are related to megatsunamis sourced by far field earthquakes along the Hellenic Arc. Megaturbidites with a more limited spatial extent are interpreted as subduction-type events in the Calabrian Arc, while thinner seismo-turbidites record the activity of crustal structures including faults onshore. Results suggest a recurrence time of 2–3 ka for major Calabrian Arc events that needs to be considered for a reliable hazard assessment in the Mediterranean region. [ABSTRACT FROM AUTHOR]

Probabilistic seismic hazard analysis (PSHA) are performed for routine applications using source models and ground motion models (GMMs) recommended by a government agency (e.g., US Geological Survey) or an expert panel (e.g., SHARE project). For important projects, site-specific PSHA involves critical analysis of GMMs and sources for the application region. We adopt the latter approach for a dam site in Calabria (southern Italy), a high seismic hazard region. We consider area sources as well as fault sources coupled with background zones, tailoring a model developed in the SHARE project for the subject site. We identify several problems with assigned maximum magnitudes for fault and in-slab subduction sources. We also add two sources not previously considered – the crustal Lakes fault and the Calabrian arc subduction interface. We select GMMs that are better constrained in the hazard-controlling range of magnitudes and distances than those typically used in prior Italian applications. Short-period median spectral accelerations at the 2475-year return period exceed those from prior SHARE studies by about 10–15%, and those from the Italian building code by amounts ranging from 15% to 96%. Despite the site being located in a region with finite faults capable of generating large events, the 2475-year hazard is dominated by source zones that allow for earthquakes directly beneath the site. [ABSTRACT FROM AUTHOR]

Along the northern Ionian margin of Calabria, three Neogene basins comprise wedge-top depozones containing syntectonic deposits which cover the frontal part of the fold-thrust belt. One of the best exposed onshore allochthonous siliciclastic successions is represented by the Cariati Nappe, cropping out in the Cirò Basin. Field geological mapping and aerial interpretations were used to characterize the stratigraphy and tectonics of the area between the Arso Stream and Nicà River catchments (about 170 km2), including a Paleozoic metamorphic basement complex unconformably overlain by Upper Oligocene to Quaternary siliciclastic deposits and minor carbonates. This paper presents a 1:25,000 scale map of the Ionian study area, providing lithological and structural data towards reconstructing its tectono-sedimentary evolution. [ABSTRACT FROM PUBLISHER]

The Catanzaro Trough is a Neogene-Quaternary basin developed in the central Calabrian Arc, between the Serre and the Sila Massifs, and filled by up to 2000 m of continental to marine deposits. It extends from the Sant’Eufemia Basin (SE Tyrrhenian Sea), offshore, to the Catanzaro Basin, onshore. Here, onshore structural data have been integrated with structural features interpreted using marine geophysical data to infer the main tectonic processes that have controlled the geodynamic evolution of the western portion of the Catanzaro Trough, since Upper Miocene to present. The data show a complex tectonostratigraphic architecture of the basin, which is mainly controlled by the activity of NW–SE and NE–SW trending fault systems. In particular, during late Miocene, the NW-SE oriented faults system was characterized by left lateral kinematics. The same structural regime produces secondary fault systems represented by E-W and NE-SW oriented faults. The ca. E-W lineaments show extensional kinematics, which may have played an important role during the opening of the WNW–ESE paleo-strait; whereas the NE-SW oriented system represents the conjugate faults of the NW-SE oriented structural system, showing a right lateral component of motion. During the Piacenzian-Lower Pleistocene, structural field and geophysical data show a switch from left-lateral to right-lateral kinematics of the NW-SE oriented faults, due to a change of the stress field. This new structural regime influenced the kinematics of the NE-SW faults system, which registered left lateral movement. Since Middle Pleistocene, the study area experienced an extensional phase, WNW-ESE oriented, controlled mainly by NE-SW and, subordinately, N-S oriented normal faults. This type of faulting splits obliquely the western Catanzaro Trough, producing up-faulted and down-faulted blocks, arranged as graben-type system (i.e Lamezia Basin). The multidisciplinary approach adopted, allowed us to constrain the structural setting of the central Calabria segment. The joined onshore with offshore structural data analysis allowed us to image a more faithful geodynamic evolution of the Calabrian Arc, included in the wider geodynamic framework of the Mediterranean region Moreover, our results show the close correlation between the NE-SW and N-S normal fault systems and evidence of deformed Quaternary deposits. These findings are relevant to seismic hazard understanding in an area which is historically considered at the highest risk of earthquake and tsunami and where are present important infrastructures and cities. [ABSTRACT FROM AUTHOR]

The Crati Graben is a depression of Plio-Holocene age mainly controlled by extensional N–S striking faults and WNW–ESE transcurrent faults, in its northern and southern extremity. It is characterized by high landslide susceptibility due to the particular geo-structural pattern and seismotectonic characters. Landslides involve many villages, infrastructure and food crops, bringing serious economic and social damage. The seismotectonic and landslidesMain Mapof the Crati Graben, described in this paper, represents an update in detail of the framework of landslide risk areas and shows the main active and recent faults of the Crati Graben. The landslides and the faults, have been identified and classified, originally at detail scale (1:5000) and, then, represented at 1:50,000 scale. The geo-structural and geomorphological data were analysed in a geographic information system. The work has revealed a correlation between the trend of faults with respect to the distribution of landslides and of the historical and instrumental seismicity. The work presents an updated knowledge framework of risk conditions of the study zone, where risk areas related to slope instability are hierarchically classified according to the destructive potential of landslides. This document may be therefore a useful reference in planning and prioritising in the design of interventions for the safety of slopes and waterways. [ABSTRACT FROM AUTHOR]

The deep seismicity and lateral distribution of seismic velocity in the Central Western Mediterranean, point to the existence under the Alboran and Tyrrhenian Seas of two lithospheric slabs reaching the mantle transition zone. Gibraltar and Calabrian narrow arcs correspond to the slabs. Similarities in the tectonic and mantle structure of the two areas have been explained by a common subduction and roll-back mechanism, in which the two arcs are symmetrical end members. We present a new 3-D tomographic model at mantle scale for the Calabrian Arc and compare it with a recently published model for the Gibraltar Arc by Monna et al. ( 2013a ). The two models, calculated with inversion of teleseismic phase arrivals, have a scale and parametrization that allow for a direct comparison. The inclusion in both inversions of ocean bottom seismometer broadband data improves the resolution of the areas underlying the seafloor networks. This additional information is used to resolve the deep structure and constrain the reconstruction of the Central Western Mediterranean geodynamic evolution. The Gibraltar tomography model suggests that the slab is separated from the Atlantic oceanic domain by a portion of African continental margin, whereas the Calabrian model displays a continuous oceanic slab that is connected, via a narrow passage (~ 350 km), to the Ionian basin oceanic domain. Starting from the comparison of the two models we propose the following interpretation: within the Mediterranean geodynamic regime (dominated by slab rollback) the geometry of the African continental margin, located on the lower plate, represents a critical control on the evolution of subduction. As buoyant continental lithosphere entered the subduction zones, slab pull caused tears in the subducted lithosphere. This tectonic response, which occurred in the final stages of arc evolution and was strongly controlled by the paleogeography of the subducted plates, explains the observed differences between the Gibraltar and Calabrian Arcs. [ABSTRACT FROM AUTHOR]

The Calabrian Arc is a narrow subduction–rollback system resulting from Africa/Eurasia plate convergence. While crustal shortening is taken up in the accretionary wedge, transtensive deformation accounts for margin segmentation along transverse lithospheric faults. One of these structures is the NNW–SSE transtensive fault system connecting the Alfeo seamount and the Etna volcano (Alfeo–Etna Fault, AEF). A second, NW–SE crustal discontinuity, the Ionian Fault (IF), separates two lobes of the CA subduction complex (Western and Eastern Lobes) and impinges on the Sicilian coasts south of the Messina Straits. Analysis of multichannel seismic reflection profiles shows that: 1) the IF and the AEF are transfer crustal tectonic features bounding a complex deformation zone, which produces the downthrown of the Western lobe along a set of transtensive fault strands; 2) during Pleistocene times, transtensive faulting reactivated structural boundaries inherited from the Mesozoic Tethyan domain which acted as thrust faults during the Messinian and Pliocene; and 3) the IF and the AEF, and locally the Malta escarpment, accommodate a recent tectonic event coeval and possibly linked to the Mt. Etna formation. Regional geodynamic models show that, whereas AEF and IF are neighboring fault systems, their individual roles are different. Faulting primarily resulting from the ESE retreat of the Ionian slab is expressed in the northwestern part of the IF. The AEF, on the other hand, is part of the overall dextral shear deformation, resulting from differences in Africa–Eurasia motion between the western and eastern sectors of the Tyrrhenian margin of northern Sicily, and accommodating diverging motions in the adjacent compartments, which results in rifting processes within the Western Lobe of the Calabrian Arc accretionary wedge. As such, it is primarily associated with Africa–Eurasia relative motion. [ABSTRACT FROM AUTHOR]

Magma upwelling forming volcanic plumbing systems in back arc settings is typically controlled by extensional tectonic structures of the upper crust. Here we investigate this process in the area between the volcanic arc of the Aeolian Islands and the Calabrian arc (SE Tyrrhenian Sea) by integrating morpho-bathymetry and reflection seismic data with the outcomes of “Inverse 3D magnetic modeling” of previously gathered aeromagnetic data. Morpho-bathymetric data highlight the presence of a seamount ∼10 km offshore Capo Vaticano Promontory (eastern Calabria). This feature, named Capo Vaticano seamount is composed of a series of NE-trending ridges, the greatest of which (R1) is ∼12 km long, and 2.4 km wide, displays asymmetric flanks with a landward steep slope, oblique morphological steps and elongated NE-trending rims. The position of the R1 ridge summit fits the Reduced-to-the-Pole peak of a high-intensity magnetic anomaly straddling Capo Vaticano Promontory and its offshore prolongation. Seismic and bathymetric data highlight two extensional fault systems affecting the offshore of Capo Vaticano Promontory during the Plio-Pleistocene: (a) a Pliocene NW-trending, SW-dipping normal fault system, and (b) a Pleistocene NE-trending, SE-dipping normal fault system. The younger system is composed of a series of en-echelon branching normal faults bounding the eastern side of the R1 ridge. Aeromagnetic data modeling imaged a complex 3D-magnetized body below the R1 ridge exhibiting a sub-vertical conduit-like structure in the shallow part, and a NE-striking, sheet-like shape inclined by 45° in depth. The location of the sub-vertical conduit coincides with the summit of the R1 ridge. The magma uprising at the root of the volcano was controlled by the Pliocene NW-trending faults whereas its further upwards migration was ostensibly controlled by the Pleistocene NE-trending faults. Both fault systems are responsible for the high level of fracturing that likely favored the upward migration of magma. The younger extensional systems also controls the present-day, mantle derived, fluid escapes observed at the summit of the R1 ridge. Relying on seismic stratigraphic evidence as well as the normal polarity of the magnetic anomaly, the R1 ridge probably started to form during the Olduvai chron (early Pleistocene, 1.81–1.96 Ma). Accordingly, the Capo Vaticano volcano may represent the result of magmatic activity that predates the Aeolian volcanic arc. [ABSTRACT FROM AUTHOR]

In the epicentral area of the seismic swarm of the June–September 2011, at southern edge of the Calabrian arc in NE Sicily, very recent extensional motions remobilised two main NW–SE dextral faults. The extensional reactivation of strike–slip faults responded to a new regional dynamic, also evidenced by GPS and seismological data. The inverted structures are aligned at the margin of a wide crustal block that is moving apart from the rest of the island and is uplifting faster than the adjacent regions. The active faults terminate to the northwest at the intersection with a prominent NNE trending fault that represents the western boundary of the mobile block. The vertical displacement along this border exactly matches the difference in elevation of the marine terraces resting inside and outside the block, respectively. On the contrary, only part of differential displacement of the marine terraces was actually accommodated as cumulative motion along the two NW oriented inverted faults, across the southwestern boundary of the block. Amounts of the vertical displacement were distributed on distinct fault planes of the previous dextral shear belts. The widespread fracturing is also the best explanation for the seismic swarm of the 2011, whose epicenters spread on a discrete rock volume rather than concentrated along a single fault plane. The diffuse fracturing seems to represent a peculiar style of deformation, connected to the tectonic inversion of previous strike–slip shear zones. Seismic swarm also affects the northern termination of the Calabrian arc where active extensional deformation reactivated previous strike–slip faults. The similarity of the two regions suggests that seismic swarm can be peculiar of extensional belts developed on previous strike–slip shear zones, along which the pre-existing geometry favours the dispersion of the tectonic motion on a network of small linked fault planes. [ABSTRACT FROM AUTHOR]

Calabria (southern Italy) is a site of considerable seismic activity related to the ongoing evolution of the Calabrian Arc system, where a complex lithospheric structure is present. For over a century the Calabrian region has been going through a period of relative seismic quietness, yet its seismic hazard is at the highest levels in the Mediterranean basin due to several catastrophic earthquakes present in the historical records. In order to strengthen the geophysical monitoring of this region, a gravity and tilt recording station was set up in the premises of the University of Calabria. The recorded signals should allow to estimate a tidal anomaly, possibly correlated with the difference between some local feature of the lithosphere or geodynamic activity and the corresponding characteristics of the model used to calculate the reference gravity tide. We report here on the results obtained by the analysis of more than two years of continuous gravity and tilt observations at a site in the northern part of the region. The tidal analysis of the gravity records, covering the time interval May 2011 - September 2013, has provided amplitudes, amplification factors and phases of the main lunar and solar gravity tidal waves. A reliable model of the gravity tide is necessary for accurate processing of discrete absolute and relative gravimetric measurements and to detect in the gravity signals possible components correlated to major seismic activity. The Ocean Tide Load (OTL) effect was accounted for in the determination of the tidal field spectral parameters. The most widespread DDW99/NH Earth's model, adopted here as reference, fits the obtained results well enough. The tidal residual vectors do not highlight any significant anomaly ascribable to the complex structure of the lithosphere beneath the region. The analysis of the tilt records points out a manifest influence of the fluctuations of the air temperature on ground slope, at annual and diurnal periods. The spectral analysis highlights the presence, on both E-W and N-S components, of a significant S1 solar wave. Values of the thermal admittance, at diurnal period, have been estimated for both tilt components. A weak energy at the frequency of 1.932 cycles/day, at the limit of statistical significance, is also observed, identifiable as the main semidiurnal lunar wave M2 of the crustal tide. The amplitude and the amplification factors of such a wave are consistent with the values expected by the DDW99/NH model. Beyond everything, the obtained results of the analyses of gravity and tilt records have provided models for the gravity tide and tidal field in the Calabrian region. Moreover, it turns out that the response of the complex lithospheric structure in the Calabrian Arc system to the tidal stress field does not produce any significant anomaly related to the adopted model. Moreover, the absolute measurements of the gravity acceleration, carried out in 1994 and 2013, yielded coinciding values, implying that during the time interval of 20 years not any significant vertical movement and/or mass redistribution in the underground occurred in the area, despite its intense geodynamic activity. [ABSTRACT FROM AUTHOR]

The Calabrian Arc subduction complex, in the northern Ionian Sea, is facing directly the westward subducting Apulian Swell, a sliver of continental crust covered by about 8 km of Mesozoic and Tertiary carbonates. Deformation patterns of this southernmost foreland segment of the Adria plate, analized from marine geological/geophysical data include: 1) flexure/bending, under the load of the advancing Calabrian Arc wedge; 2) buckling in response to compression of the surrounding orogens (southern Apennines, Dinarides-Hellenides); and 3) roll-back and eastward retreat of the slab. In this work, a reprocessed dataset of marine seismic reflection profiles is used to determine the interplay between these tectonic processes during progressive advancement of the Calabrian Arc wedge since Pliocene times. Our analysis indicates that the wedge is presently affected by compressive tectonics along several fore-thrusts, forming an imbricate fan system. Conversely, the Apulian Swell affected by inherited and rift-related Permo-Triassic normal faults, shows transpressive and positive tectonic inversions and, in its southern portion, the effects of the Hellenic fold/thrust belt shortening. The interference between the Calabrian Arc and the Hellenic chain plays an important role in controlling the tectono-stratigraphic evolution of the Apulian Swell, which underwent bending and roll-back during a pre-middle Pliocene stage followed by buckling processes. Active extension observed in the hinge zone of the Apulian Swell between Calabrian Arc and the Hellenides might suggest recent reactivation of flexure and retreat. • The response of a subducting plate trapped between two converging orogenic wedge is investigated. • The interference of Calabrian Arc (CA) and Hellenic chain plays an important role in defining the tectono-stratigraphic evolution of the Apulian Swell (AP) in Central Mediterranean Sea. • The advancement of the CA wedge and the Hellenides transmitted compressive stress to the foreland, leading to a tectonic inversion of previous Mesozoic faults. • Compressive deformation at the AP-CA wedge contact zone suggests that the west-dipping AP is already part of the orogenic wedge. • Compressive tectonics is active also in the central sector of the AP implying that collisional tectonics can be propagated over long distances from plate boundaries. [ABSTRACT FROM AUTHOR]

Detailed mapping of geomorphological and biological sea-level markers around the Capo Vaticano promontory (western Calabria, Italy), has documented the occurrence of four Holocene paleo-shorelines raised at different altitudes. The uppermost shoreline (PS1) is represented by a deeply eroded fossiliferous beach deposit, reaching an elevation of ∼2.2 m above the present sea-level, and by a notch whose roof is at ∼2.3 m. The subjacent shoreline PS2 is found at an elevation of ∼1.8 m and is represented by a Dendropoma rim, a barnacle band and by a wave-cut platform. Shoreline PS3 includes remnants of vermetid concretions, a barnacle band, a notch and a marine deposit, and reaches an elevation of ∼1.4 m. The lowermost paleo-shoreline (PS4) includes a wave-cut platform and a notch and reaches an elevation of ∼0.8 m. Radiocarbon dating of material from individual paleo-shorelines points to an average uplift rate of 1.2–1.4 mm/yr in the last ∼6 ka at Capo Vaticano. Our data suggest that Holocene uplift was asymmetric, with a greater magnitude in the south-west sector of the promontory, in a manner similar to the long-term deformation attested by Pleistocene terraces. The larger uplift in the south-western sector is possibly related to the additional contribution, onto a large-wavelength regional signal, of co-seismic deformation events, which are not registered to the north-east. We have recognized four co-seismic uplift events at 5.7–5.4 ka, 3.9–3.5 ka, ∼1.9 ka and <1.8 ka ago, superposed on a regional uplift that in the area, is occurring at a rate of ∼1 mm/yr. Our findings places new constrains on the recent activity of border faults south of the peninsula and on the location of the seismogenic source the 1905 destructive earthquake. [ABSTRACT FROM AUTHOR]

We present a new seismic velocity model for the southern Apennines–Calabrian Arc border region with the aim to better define the crustal structures at the northern edge of the Ionian subduction zone. This sector also includes the Pollino Mts. area, where a seismic sequence of thousands of small to moderate earthquakes has been recorded between spring 2010 and 2013. In this sector a seismic gap was previously hypothesized by paleoseismological evidences associated with the lack of major earthquakes in historical catalogs. To perform the tomographic inversion we selected ca. 3600 earthquakes that have occurred in the last thirty years and recorded by permanent and temporary networks managed by INGV and Calabria University. Using for the first time the Local Tomography Software for passive tomography inversion (LOTOS hereinafter) to crustal analysis in southern Italy, we have computed the distribution of Vp, Vs, and the Vp/Vs ratio. The obtained velocity model, jointly evaluated with results of synthetic modeling, as well as with the hypocenter distribution and geological information, gives us new constraints on the geodynamical and structural knowledge of the study area. The comparison between the shallow tomography sections and surface geology shows good correlation between velocity patterns and the main geological features of the study area. In the upper crust a low-velocity anomaly of P- and S-waves is detectable beneath the Pollino Mts. area and seems to separate the Calabrian and southern Apennines domains, characterized by higher velocities. The distributions of high Vp/Vs ratio, representing strongly fractured rocks with likely high fluid content, clearly correlate with areas of significant seismicity. In the lower crust we detect a clear transition from high to low seismic velocities in correspondence with the Tyrrhenian coast of the study area, which may represent the transition from the thinner Tyrrhenian crust to the thicker one beneath Calabria. In this area, also characterized by a progressive detachment of a retreating lithospheric slab, the generation of a Subduction-Transform Edge Propagator (STEP) fault zone, that laterally decouples subducting lithosphere from non-subducting lithosphere in a scissor type of fashion, may have taken place. These conditions imply the existence of a kinematic decoupling which allows for differential movement between the Calabrian Arc and the southern Apennine chain. The low velocity anomaly separating the southern Apennines and the Calabrian Arc domain may be related to fluid upwelling occurring in correspondence with the northern edge of the Calabrian subducting slab. [ABSTRACT FROM AUTHOR]

Low-field anisotropy of magnetic susceptibility (AMS) analyses were performed on 532 samples collected in 36 (mostly lower Pliocene to lower Pleistocene) marine clay sites from the Crotone basin, a fore-arc basin located on top of the external Calabrian accretionary wedge. The Crotone basin formed since mid-late Miocene under a predominant extensional tectonic regime, but it was influenced thereafter by complex interactions with NW–SE left-lateral strike-faults bounding the basin, which also yielded post-1.2 Ma ∼30° counterclockwise block rotations. The basin is filled by continental to marine sediments yielding one of the thickest and best-exposed Neogene succession available worldwide. The deep-marine facies – represented by blue-grey marly clays gave the best results, as they both preserved a clear magnetic fabric, and provided accurate chronology based on previously published magnetostratigraphy and calcareous plankton (i.e. foraminifers and nannofossils) biostratigraphy. Magnetic susceptibility range and rock magnetic analyses both indicate that AMS reflects paramagnetic clay matrix crystal arrangement. The fabric is predominantly oblate to triaxial, the anisotropy degree low (<1.06), and the magnetic foliation mostly subparallel to bedding. Magnetic lineation is defined in 30 out of 36 sites (where the e12 angle is <35°). By also considering local structural analysis data, we find that magnetic fabric was generally acquired during the first tectonic phases occurring after sediment deposition, thus validating its use as temporally dependent strain proxy. Although most of the magnetic lineations trend NW–SE and are orthogonal to normal faults (as observed elsewhere in Calabria), few NE–SW compressive lineations show that the Neogene extensional regime of the Crotone basin was punctuated by compressive episodes. Finally, compressive lineations (prolate magnetic fabric) documented along the strike-slip fault bounding the basin to the south support the significance of Pleistocene strike-slip tectonics. Thus the Crotone basin shows a markedly different tectonics with respect to other internal and western basins of Calabria, as it yields a magnetic fabric still dominated by extensional tectonics but also revealing arc-normal shortening episodes and recent strike-slip fault activity. The tectonics documented in the Crotone basin is compatible with a continuous upper crustal structural reorganization occurring during the SE-migration of the Calabria terrane above the Ionian subduction system. [ABSTRACT FROM AUTHOR]

A powerful cartographic tool in identifying major tectonic lineaments and/or ancient margins along the Sicilian and southern Calabria Orogenic system (southern Italy) has been obtained by producing the 1:250,000 scale digital contour map of gravity anomalies available for the Italian region. By processing contour maps, an ‘elevation model’ of the gravity anomalies for Sicily and southern Calabria was produced. The ‘elevation model’ was used to generate a slope representation of the gravity trend that is presented in this paper at 1:500,000. The map covers an area of about 95,000 km2and includes both the inland areas of Sicily and southern Calabria and the adjacent seas. The color of the pixels varies from blue, where no significant variation of the gradient occurs, to red with the steepest gradients. Taking into account (i) the nature of rocks which are involved in the analyzed orogenic system and (ii) the juxtaposition of rocks with different densities is usually controlled by faults, the thematic map here presented can provide an additional tool for a regional scale tectonic interpretation of this sector of the Central Mediterranean. [ABSTRACT FROM AUTHOR]

Abstract: The 28 December, 1908 Reggio Calabria and Messina earthquake (named after the two most damaged cities on the coasts of Messina Strait) was one of the strongest (MW 7.1) ever to occur in Italy, and was also followed by a tsunami that severely impacted the coasts of the Strait. Although there is general agreement that its epicentre is located offshore in the Messina Strait, the source fault has never been detected; a century-long question is therefore pending on the source of both the 1908 earthquake and tsunami. Within the ongoing debate on this subject, little attention has been given, so far, to morphological insights from high resolution bathymetric (multibeam) data, particularly as regarding the evidence of faults affecting the seafloor and the question of whether a submarine landslide may had been the cause of the tsunami. We aim to address this issue by presenting the results of a morpho-bathymetric study in the Messina Strait and surroundings, investigated by means of high-resolution swath bathymetry. The primary morpho-structural feature in this area is the axial channel of the Messina Canyon, towards which flow several tributary canyons that incise the steep continental slope on the Calabrian and Sicilian margins. These canyons carve deeply into a very narrow (almost lacking) continental shelf and merge laterally forming a continuous erosional margin rimming the Messina Strait. This giant, composite canyon environment is the locus of intense erosional and depositional processes that superimpose on active tectonic deformation, resulting in a complex geomorphology that hinders the distinction between tectonic and sedimentary features. Seafloor ruptures that may be linked to fault systems compatible with the source of the 1908 earthquake and tsunami could not be identified based from our morpho-bathymetric analysis; however, we provide evidence of several geomorphic features indicative of tectonic deformation in the Messina Strait, define the presence and distribution of submarine landslides, and evaluate their possible role as tsunami sources. [Copyright &y& Elsevier]