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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.

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.

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.

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.

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]

[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]

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 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]

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]

Stanley, J.-D.; Bernasconi, M.P., and Nickerson G.A.J., 2014. Large scarps and massive slide on the Briatico-Bivona shelf, Calabria, Italy: potential link with the destructive September 1905 earthquake. A multibeam sonar (MBS) survey of the northern Capo Vaticano shelf between the towns of Briatico and Bivona, Calabria, Italy, has revealed a markedly broken margin offset by three large scarps: the upper scarp (S1) at approximate depths of 16-22 m, the middle scarp (S2) at ∼36-58 m, and the deeper scarp (S3) at ∼88-101 m. The configuration of S1 shows high relief to 33 m and a slope to 59°, which suggests a fault or tectonic-gravitative origin. Substantial volumes of sediment, mostly sand, are being rapidly transferred from the inner shelf toward and across the upper shelf break, and one could expect a smoothing and burial of the upper scarp, but 10 MBS profiles show the sharp, angular shape of that feature. Some of the mass gravitative deposits just below some headwall scarps that extend to the shelf-slope that break NE of Briatico also reveal very recent origins. Additionally, a massive slide block north of Bivona, ∼350-400 m in length, appears to have detached from the inner shelf and shifted onto the middle shelf. It is proposed that several of these seafloor features may, in some manner, be associated with the powerful and destructive September 1905 earthquake that affected a large sector of Calabria. Five potential epicenters on the SW margin of Calabria have previously been proposed for that event, and this MBS study area is in proximity to one of those. It is recommended that two localities in the survey area, one NE of Briatico and the other north of Bivona, be selected as test zones for further geological and geophysical analyses. [ABSTRACT FROM AUTHOR]

In 1998-1999 a seismic sequence occurred in the Southern Apennines, after the moderate size (mb=5.0) 9th September 1998 Pollino earthquake. It lasted about 14 months and was clearly localized to the sole north-west area of the main shock epicenter. Its peculiarity consisted in sudden changes of activity from a series of normal faults with Apenninic (NW-SE) trend and transfer, presumably strike slip, faults with Antiapenninic (NE-SW) and E-W trend. The complexity of the behavior and the different orientations of the activated systems suggest that the area acts as a hinge between the NW-SE trending Southern Apennines and the locally N-S trending Calabrian Arc.

A geophysical survey provides new information on marine features located seaward of Locri-Epizefiri (Locri), an ancient Greek settlement on the Ionian coastal margin in southern Italy. The study supplements previous work by archaeologists who long searched for the site's harbor and recently identified what was once a marine basin that is now on land next to the city walls of Locri. Profiles obtained offshore, between the present coast and outer shelf, made with a high-resolution, seismic subbottom-profiling system, record spatial and temporal variations of buried Holocene deposits. Two of these submerged features are part of a probable now-submerged ship landing facility. The offshore features can be linked to coastline displacements that occurred off Locri: a sea-to-land shift before Greek settlement, followed by a shoreline reversal from the archaeological site back to sea, and more recently, a return landward. The seaward directed coastal shift that occurred after Locri's occupation by Greeks was likely caused by land uplift near the coastal margin and tectonic seaward shift of the coast, as documented along this geologically active sector of the Calabrian Arc. The seismic survey records an angular, hook-shaped, low rise that extends from the present shore and is now buried on the inner shelf. The rise, enclosing a core lens of poorly stratified to transparent acoustic layers, bounds a broad, low-elevation zone positioned immediately seaward of the shoreline. Close proximity of the raised feature to the lowelevation area suggests it may have been a fabricated structure that functioned as a wave-break for a ship-landing site. The study indicates that the basin extended offshore as a function of the coastline's seaward migration during and/or after Greek occupation of Locri. [ABSTRACT FROM AUTHOR]

The Sibari Plain in the Northeastern Calabrian Arc displays a well-developed suite of marine terraces. This paper deals with i) the identification and correlation of the terraces; ii) their age assignment and a tentative reconstruction of the uplift history of the area; iii) the relationships between terraces and major faults in the study area and between uplift in the Plain and pattern of Quaternary uplift throughout the Calabrian Arc. Identifying wavecut platforms and inner-edge fragments over a linear extent of ~ 100 km was achieved by photo interpretation, 1:25 000 scale map analyses and field survey. Morphological evidence led to the correlation of the identified fragments into five complete strandlines (numbered #1 to #5 lowest to highest), at elevations ranging from 60 m to ~ 650 m. Analysis of two parameters of the emerged platform-cliff systems, namely the platform-cliff ratio and the dissection percentage, further testifies that the two lowest terraces are strongly correlative. A 130 kyr AAR age of in situ fossil samples of Glycymeris collected at 114 m elevation within the deposit of Terrace #2 indicates a key correlation of T#2 with MIS 5.5 (the peak of the last interglacial, 124 kyr), i.e. an uplift rate of ~ 0.98 mm/yr for this strandline. The other four terraces have been tentatively associated with MIS 5.3, 7, 9 and 15. Geological observations independent of geochronological evidence provide consistent lower age boundaries for the terraces and supply further constraints to this interpretation. Investigating the relations between setting of the terraces and location of major tectonic structures in the region is suggestive of no recent activity of two previously recognized faults, the «Sangineto Line» and the «Corigliano-Rossano Line». Instead, some limited anomalies that affect the terraces are tentatively associated with the activity of the Castrovillari Fault. Therefore, sustained uplift has been the long-term dominant process of tectonic deformation in the study area over the past 124 kyr, possibly 600 kyr. Rates and history of uplift in the Sibari Plain are largely comparable with those observed in the whole Calabrian Arc, confirming that the uplift driving mechanism is deep-seated and closely connected to the Tyrrhenian subduction as already pointed out by several authors. Despite a dearth of Holocene raised paleoshorelines, it is suggested that similarly to what was observed only few tens of kilometres north and south of the Sibari Plain, the Late Pleistocene rise is still active today and that without Holocene uplift the Plain should have been far less developed and attractive for human settlement.

Abstract: It is rarely possible to identify reverse faults that bring portions of substratum solid rock to lie above decomposed rock. Only where the differences between the fresh rock and weathered rock are very clear is it possible to recognise such faults. A “reverse profile” is defined as a slope profile in which fresh rock (granitoids) overlaps rocks which have been greatly altered by mature weathering (saprolite of granitoids). Such a profile occurs along the slopes of Molini Valley to the south of the village of Fabrizia (Calabria, southern Italy) and we interpret the morphological, mechanical and structural evidence as typical of a reverse fault. The mineral-petrographic analysis of the grus on the bed of the fault and of the cover of relatively fresh rock (Schmidt hammer 18–35) confirms that the granular framework can be attributed to subaerial alteration and not to mechanical deformation. The study area is located at the centre of the largest kinematic body of southern Calabria (the Serre massif-exclusively granitoids) until now considered to be only affected by extensional tectonics, creating high angle normal faults. In this area the tectonic processes, the thickness and spread of granitoid weathering mantles and the depth of the valleys, give rise to several landslides. These are generally translational slides with ample cut surfaces between the weathered body and the underlying fresh rock; as a consequence, very large deposits in the valleys can be found, mostly produced by debris flow processes. At the foot of the slopes around Fabrizia, coarse debris avalanches (with cobbles having a volume of over 0.3–0.4 m3) are occasionally observed, unless there is widespread development of a “reverse weathering profile” on the slopes above. [Copyright &y& Elsevier]

A seismic array of 11 stations maintained for 9 years—from 1985 to 1994—provided data that were exploited for the investigation of the 3-D structure of the upper crust in the Gioia Tauro basin, south-western Calabria, Italy. A data set of 207 local earthquakes that were located with a minimum of seven observations, a traveltime residual of ≤0.3 s rms and an azimuthal gap ≤180° was used to compute first a minimum 1-D velocity model for the Gioia Tauro region, which served as initial model for the subsequent 3-D inversion. The inversion for 3-D P-velocity crustal structure was performed by iteratively solving the coupled hypocentre-velocity problem in a least-squares sense. Careful analysis of the resolution capability of our data set outlines the well-resolved features for interpretation. The resulting 3-D velocity model of the Gioia Tauro region shows, in the upper crust, generally higher average velocities in the south and lower average velocities in the north. A pronounced northeast-southwest trending zone of low velocities in the upper 12 km was identified in the area of the Cittanova fault zone (CFZ). Because of the limited dimensions of the seismic array the half graben of Gioia Tauro basin could not be recognized in the tomographic images. [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. [ABSTRACT FROM AUTHOR]