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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]

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.

[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]

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]

The development of Punta Stilo Swell (PSS), a submerged lobate-shaped promontory located in the Crotone-Spartivento Basin, is inferred to be closely linked to the Calabrian Arc kinematics since mid-Miocene onward. The latter consists of an alternation between long-term phases of subsidence related to forward migration of the Calabrian accretionary complex, and short-term compressional-transpressional phases, characterized by episodes of uplift and formation of regional unconformities, in a context of stopping or slowdown of Calabrian accretionary complex migration. In particular, the study area is supposed to have respectively experienced phases of compressional and extensional tectonics during late Messinian and early Pliocene, which likely produced a reactivation of inherited compressional and extensional structures. Late Pliocene/Pleistocene transtensional tectonics is documented along the offshore extension of the Soverato-Lamezia Fault Zone (SLFZ), in the N sector of the PSS. The resulting physiographic modifications associated with such compressional, extensional and transtensional tectonics is believed to have controlled the accumulation of the thick Plio-Pleistocene succession of the PSS. The northern continental slope is inferred to be the result of late Pliocene/Pleistocene transtensional tectonics occurred along the SLFZ, whereas the shelf break is considered the result of an early Pliocene extensional tectonics. The considerable steepness (>10°) of the southern and eastern continental slope of the PSS is associated with the late Messinian compressional tectonic activity and is marked by the occurrence of slope failure-associated events. • The PSS was generated from late Messinian to Pleistocene compressional, extensional and transtensional tectonics. • The tectonic evolution of the PSS is linked to the central Mediterranean geodynamics. • The present-day steepness of the slope setting is the expression of the late Messinian compressional tectonics. [ABSTRACT FROM AUTHOR]