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Submarine landslides are very large events occurring across both active and passive continental margin. They are sediment transport processes caused by submarine slope’s instability and the result of both internal structure changes and external dynamic conditions. The genesis and evolution of slope failure is controlled by different geological factors which may be considered as predisposing factors (e.g., seafloor morphology, lithology, type of sediment, presence of fluid or weak layers) and triggering factors (e.g., earthquakes).The Italian continental margins provide an excellent playfield to study submarine landslides because they have been identified and mapped in different morpho-tectonic and sedimentary contexts (e.g., accretionary prism, volcanic edifices, foredeep continental slope, upper slope in front of large deltas…). Between the 2007 and 2013, in the framework of MaGIC project funded by the Italian Civil Protection (DPC) a detailed mapping program of seafloor morphologies and features including landslides was carried out. The morphological features identified during the Magic Project will be used as a base to create a geodatabase of the Italian submarine landslides. This will include a careful reclassification of the different features, extraction of morphometric parameters and identification of triggering and preconditioning factors for the different case studies. This work has been funded by PNRR GEOSCIENCES IR project, and aim at use statistical methods to better classify the landslides that are relate than to different geological settings, and constrain the relation between different parameters and the triggers. When a relation will be established, we may build a step towards a better geohazard assessment, and may be define the likelihood of submarine landslide occurrences across the Italian Continental Margins, even in the areas when the landslides did not occurred yet. In fact, landslide hazard assessment requires the estimation of where, when (or how frequently) and how large a given landslide event may be. In marine realm this is very difficult because the cost of direct analysis is higher than in the subaerial counterpart. Therefore, a geostatistical approach on very large number of features could probably be the most realistic approach to the problem.

Mud and fluids migration producing active seepage at the seafloor is a global phenomenon documented in different geodynamic contexts. Scoglio d’Affrica islet is one of the culminations of the Elba-Pianosa Ridge (northern Tyrrhenian Sea), where submarine methane emissions have been studied since the 1960’s, sometimes evolving in violent gas outbursts such as those occurred in 2017. In the study area, the seafloor is punctuated by more than 250 small pockmarks with mean diameter of 10 m and occurring mainly between 20 and 60 m water depth. Pockmarks are characterized by planform shapes from sub-circular to elongated and U/V-shaped cross-sections. They are predominantly arranged as isolated or in clusters or minorly organised in strings-oriented about N-S, running almost parallel to the fault escarpments which represent one of the main structural features of the study area. Pockmarks have been classified on the basis of their size parameters (i.e., depth, mean diameter) according to the recent literature and they resulted to belong mainly to the morphological classes of the "unit pockmark" and minorly to the “normal pockmark”. The complex seafloor morphology of the area is also characterised by several positive features, showing very different shapes and sizes (up to 35 m high and 600 m wide). In this work, we select 67 positive features (named as M1-67) more than 2 meters high and perform on them the first morphometric analysis by means of high-resolution bathymetric data. The obtained morphometric parameters (e.g., flatness value, mean slope), which allow us to classify the positive features as mounded, flat topped and conical features, are compared with those of other submarine mud volcanoes from literature, showing often high similarity. In view of that, we suggest that M1-67 have an origin likely linked to the migration of fluidised mud or mud breccia (a mud matrix with clasts), probably from shallow mud sources, rising through the thick Eocene-Early Miocene siliciclastic succession and overlying sedimentary layers. We interpret as mud volcanoes the larger sub-circular positive features (M1-7) since they are characterised by the occurrence of lobate flows along their flanks, widespread mud-breccia and focused emissions of CH4 observed on ROV videos. Whilst, with the available data, to avoid any speculation, we propose for M8-67 an alternative and more generic explanation interpreting them as “piercement structures” formed due to the seafloor deformation associated with a rising mud diapirism. Considering the high-magnitude outburst occurred in 2017 and the shallow water setting with evidence of active fluid seepage (as vertical focused gas bubbles) documented by ROV videos, the morphometric analysis of mud and fluids migration morphologies is an important baseline study since it can provide insight for a marine geohazard assessment around Scoglio d’Affrica islet.

Shallow seabed depressions attributed to focused fluid seepage, known as pockmarks, have been documented in all continental margins. In this study we demonstrate how pockmark formation can be the result of a combination of multiple factors – fluid type, overpressures, seafloor sediment type, stratigraphy, and bottom currents. We integrate multibeam echosounder and seismic reflection data, sediment cores and pore water samples, with numerical models of groundwater and gas hydrates, from the Canterbury Margin (off New Zealand). More than 6800 surface pockmarks, reaching densities of 100 per km2, and an undefined number of buried pockmarks, are identified in the middle to outer shelf and lower continental slope. Fluid conduits across the shelf and slope include shallow to deep chimneys/pipes. Methane with a biogenic and/or thermogenic origin is the main fluid forming flow and escape features, although saline and freshened groundwaters may also be seeping across the slope. The main drivers of fluid flow and seepage are overpressure across the slope generated by sediment loading and thin sediment overburden above the overpressured interval in the outer shelf. Other processes (e.g. methane generation and flow, a reduction in hydrostatic pressure due to sea-level lowering) may also account for fluid flow and seepage features, particularly across the shelf. Pockmark occurrence coincides with muddy sediments at the seafloor, whereas their planform is elongated by bottom currents.

We present a very high-resolution bathy-morphological map of the offshore sector around the Scoglio d’Affrica islet (northern Tyrrhenian Sea, Italy). The study area covers a sector of 45 km2, between 3 and 85 m depth. Its central part, i.e. the apex of the Ridge, is characterised by a flat or gently sloping seafloor, where three mud volcanoes, and 250 pockmarks are recognised. Differently, the western and eastern Ridge flanks are steeper and characterised by 60 quasi-rectilinear escarpments and small ridges, more than 20 morphological highs, and elongated channels occasionally floored by bedforms. The seafloor shallower than 40 m is covered by Posidonia oceanica, forming compact and continuous or fragmented meadows intermingled with sandy patches. The main map represents the bathy-morphological setting of the area, which is largely affected by fluid seepage, providing insights for habitat mapping and preliminary marine geohazard assessment due to the violent gas outburst from mud volcanoes.

The Maltese Islands (central Mediterranean Sea) are intersected by two normal fault systems associated with continental rifting to the south. Because of a lack of evidence for offshore displacement and insignificant historical seismicity, the systems have been considered to be inactive. Here we integrate aerial and marine geological, geophysical and geochemical data to demonstrate that: (i) the majority of faults offshore the Maltese Islands underwent extensional to transtensional deformation during the last 20 ka, (ii) active degassing of CH4 and CO2 occurs via these faults. The gases migrate through Miocene carbonate bedrock and the overlying Plio-Pleistocene sedimentary layers to generate pockmarks at the muddy seafloor and rise through the water column into the atmosphere. We infer that the offshore faults systems are permeable and that they were active recently and simultaneously. The latter can be explained by a transtensional system involving two right-stepping, right-lateral NW-SE trending faults, either binding a pull-apart basin between the islands of Malta and Gozo or associated with minor connecting antitethic structures. Such a configuration may be responsible for the generation or reactivation of faults onshore and offshore the Maltese Islands, and fits into the modern divergent strain-stress regime inferred from geodetic data., peer-reviewed

18 pages, 13 figures, 1 table, We present here for the first time a morpho-structural study of the submarine sector of the Ustica volcanic edifice, located in the south-western Tyrrhenian Sea, considered as an inactive volcanic system, middle Pleistocene in age. The main aim of this research study is to unravel the submarine dynamics along the slope sectors of the Ustica volcano, in order to provide new insights on one of the most tectonically active regions of the Central Mediterranean during the Quaternary. We analysed and interpreted an integrated seismo-acoustic data set consisting of multibeam swath-bathymetry, sub bottom profiles, single-channel seismic reflection records, all of them acquired during the last two decades. The seismostratigraphic analysis indicates that the Ustica volcano is composed by a sequence of lava flows and pyroclastic products, whose geometry can be interpreted as the consequence of combined upward growing and northward shifting of the volcanic centers. The mapped geomorphological elements distributed along the submerged slopes were classified based on their specific morphogenetic process. The achieved results reveal that volcanic, tectonic, oceanographic and gravity processes interacted in shaping the complex current physiography of the volcanic edifice, which is characterized by extremely uneven submarine flanks. The northern region is characterized by the widespread occurrence of well-preserved cones, probably linked to the last submarine volcanic activity of the area. Along the eastern sector, elongate gullies and linear furrows locally incise the shelf break and develop downward producing slope failures. Furrows and gullies represent the main conduits for flushing sediments through various types of flows and mass wasting, from the shallow sectors to the bathyal plain. Along the southern and eastern region slope failures processes carve almost totally of the shelf edge and mainly propagate through retrograding collapses. Further on, the southern region is mainly shaped by E-W and N-S trending fault escarpments that may have triggered the largest slope failures of the area. The main results of this study contribute to improve the understanding of the geological processes and geodynamic activity between the Northern Sicily Continental Margin and the Tyrrhenian Basin and represent a baseline for assessing the geo-hazard potential on the Ustica Island, We acknowledge the CARG Project (Geological Maps of Italy) funded by the ISPRA-Italian Geological Survey and the Italian National Research Projects MaGIC (Marine Geological Hazard along the Italian Coast) funded by the Italian Civil Protection Department.-- With the funding support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI)

We present the results of an integrated geomorphological and seismo-stratigraphic study based on high resolution marine data acquired in the north-western Sicilian continental margin. We document for the first time five contourite drifts (marked as EM1a, EM2b, EM2, EM3a, and EM3b), located in the continental slope at depths between ca. 400 and 1500 m. EM1a,b have been interpreted as elongated mounded drifts. EM1a,b are ca. 3 km long, 1.3 km wide, and have a maximum thickness of 36 m in their center that thins northwards, while EM1b is smaller with a thickness up to 24 m. They are internally characterized by mounded seismic packages dominated by continuous and parallel reflectors. EM2 is located in the upper slope at a depth of ca. 1470 m, and it is ca. 9.3 km long, more than 3.9 km wide, and has a maximum thickness of ca. 65 m. It consists of an internal aggradational stacking pattern with elongated mounded packages of continuous, moderate to high amplitude seismic reflectors. EM2 is internally composed by a mix of contourite deposits (Holocene) interbedded with turbiditic and/or mass flow deposits. EM1a,b and EM2 are deposited at the top of an erosional truncation aged at 11.5 ka, so they mostly formed during the Holocene. EM3a,b are ca. 16 km long, more than 6.7 km wide, and have a thickness up to 350 m. Both EM2 and EM3a,b have been interpreted as sheeted drift due to their morphology and seismic features. The spatial distribution of the contourite drifts suggests that the drifts are likely generated by the interaction of the LIW, and deep Tyrrhenian water (TDW) on the seafloor, playing an important role in the shaping this continental margin since the late Pleistocene-Holocene. The results may help to understand the deep oceanic processes affecting the north-western Sicilian continental margin.

The Messinian salinity crisis was an extraordinary event that resulted in the deposition of kilometre-thick evaporite sequences in the Mediterranean Sea after the latter became disconnected from the world's oceans. The return to fully and stable marine conditions at the end of the crisis is still subject to debate. Three main hypotheses, based on geophysical and borehole data, onshore outcrops and climate simulations, have been put forward. These include a single-stage catastrophic flood, a two-step reflooding scenario, and an overspill of Paratethyan water followed by Atlantic inflow. In this study, two research questions are addressed: (i) Which event marked the termination of the Messinian salinity crisis? (ii) What was the sea level in the eastern Mediterranean Sea during this event? Geophysical data from the western Ionian Basin are integrated with numerical simulations to infer that the termination of the crisis consisted of a single-stage megaflood following a sea level drawdown of 1900 m. This megaflood deposited an extensive sedimentary body with a chaotic to transparent seismic signature at the base of the Malta Escarpment. Fine, well-sorted sediments are predicted to have been deposited within the thicker sections of the flood deposit, whereas a more variable distribution of coarser sediments is expected elsewhere. The north-western Ionian Basin hosts evidence of episodic post-Messinian salinity crisis slope instability events in the last ~1.8 Ma. The largest of these emplaced a >200 km3 deposit and is associated with failure of the head of Noto Canyon (offshore SE Sicily). Apart from unravelling the final phase of the Messinian salinity crisis and the ensuing stratigraphic evolution of the western Ionian Basin, our results are also relevant to better understand megafloods, which are some of the most catastrophic geological processes on Earth and Mars. © 2020 Elsevier B.V., The article is based upon work from COST Action CA15103 “Uncovering the Mediterranean salt giant” (MEDSALT) supported by ( COST European Cooperation in Science and Technology ). We are indebted to the CUMECS-2, CUMECS-3 and CIRCEE-HR shipboard parties, captains, crew and technicians for their assistance during data collection. The oceanographic surveys were possible following permits issued by the Italian and Maltese authorities. SPECTRUM (now TGS) are kindly acknowledged for providing access to their seismic reflection data. The use of CROP seismic profiles has been licensed to OGS by CNR, Banca Dati CROP ( www.crop.cnr.it ). The authors would also like to thank Emerson Paradigm for the use of the OGS academic licenses of the ECHOS and Geodepth processing software, and IHS Markit for the OGS license of the Kingdom software. DS is funded by EMODnet Bathymetry, which is financed by the European Union under Regulation 508/2014 of the European Parliament and of the Council of 15 May 2014 on the European Maritime and Fisheries Fund . This work was also supported by the Spanish Ministry of Science, Innovation and Universities (MICINN/FEDER, EU) under Grant SEDRETO CGL2015–70736-R . J.D.d.M.E. was supported by the PhD scholarship BES-2016-079117 (MINECO/FSE, EU) from the Spanish National Programme for the Promotion of Talent and its Employability (call 2016). This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 765256 (SaltGiant ITN).

The MARCAN project, launched last January, is working to fill a gap in our knowledge of how freshwater flowing underground shapes and alters the continental margins.

The Maltese Islands, located in the central Mediterranean Sea, are intersected by two normal fault systems associated with continental rifting to the south. Due to a lack of evidence for offshore displacement and insignificant historical seismicity, the systems are thought to be inactive and the rift-related deformation is believed to have ceased. In this study we integrate aerial, marine and onshore geological, geophysical and geochemical data from the Maltese Islands to demonstrate that the majority of faults offshore the archipelago underwent extensional to transtensional deformation during the last 20 ka. We also document an active fluid flow system responsible for degassing of CH4 and CO2. The gases migrate through carbonate bedrock and overlying sedimentary layers via focused pathways, such as faults and pipe structures, and possibly via diffuse pathways, such as fractures. Where the gases seep offshore, they form pockmarks and rise through the water column into the atmosphere. Gas migration and seepage implies that the onshore and offshore faults systems are permeable and that they were active recently and simultaneously. The latter can be explained by a transtensional system involving two right-stepping, right-lateral NW-SE trending faults, either binding a pull-apart basin between the islands of Malta and Gozo or associated with minor connecting antitethic structures. Such a configuration may be responsible for the generation or reactivation of faults onshore and offshore the Maltese Islands, and fits into the modern divergent strain-stress regime inferred from geodetic data.

Active fluid seepage (AFS) at the seafloor is a global phenomenon associated with seafloor morphologies in different geodynamic contexts. Advanced geophysical techniques have allowed geoscientists to characterise pockmarks, mounds and flares associated with AFS. We present a range of new marine geological data acquired in the southern region of the central Mediterranean Sea (northern Sicily continental margin, northwestern Sicily Channel and offshore of the Maltese Islands), which allow us to identify AFSs. AFSs are spatially distributed as clusters, aligned or isolated at different depths, ranging from few decametres offshore of the Maltese Islands; up to 400 m offshore of northern Sicily and in the northwestern Sicily Channel. Mounds have heights ranging from 2 to 15 m and form hummocky surfaces. Seafloor samples were collected at the top of the mounds and were analysed using a SEM with an EDX. Geochemical features reveal that seafloor samples are slightly enriched in O, S and Ba and seem to indicate the existence of an external source of fluids and the occurrence of sediment-fluids interaction processes. Pockmarks with sub-circular planform shapes and U/V-shaped cross-sections are found in sizes ranging from 5 to 530 m. Gas flares occur on both the continental shelf as well as the upper slope.

Carbonate escarpments are submarine limestone and dolomite cliffs that have been documented in numerous sites around the world. Their geomorphic evolution is poorly understood due to difficulties in assessing escarpment outcrops and the limited resolution achieved by geophysical techniques across their steep topographies. The geomorphic evolution of carbonate escarpments in the Mediterranean Sea has been influenced by the Messinian salinity crisis (MSC). During the MSC (5.97–5.33 Ma), the Mediterranean Sea became a saline basin due to a temporary restriction of the Atlantic-Mediterranean seaway, resulting in the deposition of more than one million cubic kilometres of salt. The extent and relative chronology of the evaporative drawdown phases associated to the MSC remain poorly constrained. In this paper we combine geophysical and sedimentological data from the central Mediterranean Sea to reconstruct the geomorphic evolution of the Malta Escarpment and infer the extent and timing of evaporative drawdown in the eastern Mediterranean Sea during the MSC. We propose that, during a MSC base-level fall, fluvial erosion formed a dense network of canyons across the Malta Escarpment whilst coastal erosion developed extensive palaeoshorelines and shore platforms. The drivers of geomorphic evolution of the Malta Escarpment after the MSC include: (i) canyon erosion by submarine gravity flows, with the most recent activity taking place, This research was undertaken with funding from Marie Curie Career Integration Grant PCIG13-GA-2013-618149 (SCARP), ERC Starting Grants n°258482 (CODEMAP) and n°677898 (MARCAN), and collaborative project n°228344 (EUROFLEETS), all within the 7th European Community Framework Programme and the Horizon 2020 Programme. Financial support was also provided by the Fulbright Visiting Scholar Program, Royal Society of New Zealand (through the International Mobility Fund), New Zealand Crown Research Institute SSIF funding to NIWA, the Griffith Geoscience Awards (Department of Communications, Energy and Natural Resources under the National Geoscience Programme 2007–2013 of Ireland), and the David and Lucile Packard Foundation. MAG acknowledges INSU for cruise-related funding and the European Union FP7 project ASTARTE for post-cruise financial support. The article is based upon work from COST Action CA15103 “Uncovering the Mediterranean salt giant” (MEDSALT) supported by COST (European Cooperation in Science and Technology).

A. Micallef et. al., The Messinian salinity crisis (MSC)-the most abrupt, global-scale environmental change since the end of the Cretaceous-is widely associated with partial desiccation of the Mediterranean Sea. A major open question is the way normal marine conditions were abruptly restored at the end of the MSC. Here we use geological and geophysical data to identify an extensive, buried and chaotic sedimentary body deposited in the western Ionian Basin after the massive Messinian salts and before the Plio-Quaternary open-marine sedimentary sequence. We show that this body is consistent with the passage of a megaflood from the western to the eastern Mediterranean Sea via a south-eastern Sicilian gateway. Our findings provide evidence for a large amplitude drawdown in the Ionian Basin during the MSC, support the scenario of a Mediterranean-wide catastrophic flood at the end of the MSC, and suggest that the identified sedimentary body is the largest known megaflood deposit on Earth. © 2018 The Author(s)., This work was supported by Marie Curie Career Integration Grant PCIG13-GA-2013–618149 (SCARP) within the 7th European Community Framework Programme, and the European Research Council under the European Union’s Horizon 2020 Programme (grant agreement n° 677898 (MARCAN)).

In the Sicily Channel, (Central Mediterranean), two geodynamic processes overlap each other, the Maghrebides- Apennines accretionary prism and the Sicily Channel rift. Moreover, the northwestern sector (Banks sector) is characterised by an irregular seafloor morphology linked to the recent volcanic and tectonic activity.In order to discriminate the role exerted by both the processes in the morphostructural setting of the area we used a dataset of both high and very high resolution single-channel and multi-channel profiles, acquired in the frame of the RITMARE project respectively with CHIRP and sparker, and airgun sources, and high resolution (5 m cell) morpho-bathymetric data. The data allowed us to identify and characterise two areas where different geological features (sedimentary and volcanic) are prevailing. They present fluid escaping evidence, which often appears to be active and generating different types of morphologies (both positive and negative). In the western sector we recognised pockmarks at water depths of 195 to 317 m, with diameters from 25 to 580 m, depths from 1.3 to 15 m, and slope up to 23. They show sub-circular shape in plan-view and reflectors with upward concavity in cross section, and are oriented along a NW-SE trend.The CHIRP and multichannel profiles highlight fluids that affect the Plio-Quaternary succession, especially in areas where the top surface of the Messinian succession is shallower. Conversely, wipe-out acoustic facies were recognised in proximity of: i) extensional faults of Mesozoic age with NW-SE trend; ii) dip/strike slip faults of Cenozoic age with NW-SE, N-S and about NNE-SSW trends, and iii) extensional neo-tectonic faults with NW-SE and NNW-SSE trends. We cannot exclude that they could feed the shallower reservoir producing a mixing between the two. In the eastern sector we recognised a cluster of volcanoes composed of seven cone-shaped structures (SCV1-7), pertaining to a wide area known as Graham Bank. A detailed morphometric analysis of these volcanoes has been conducted: they are up to about 115-160 m high and 500-1500 m wide. Most of them show very strongly inclined flanks with 30 of average slope. The SCV2 and SCV3 form the Graham Bank, 3.5X2.8 km wide, elongated in the NW-SE direction. At the top of SCV2 focused seepage plumes were observed in the entire water column, through the CHIRP data, where we calculated that they release, a volume of about 10950 m3 and 43960 m3of gases, respectively. In this work, we present the first results of a data collection that have got as main result the identification and mapping of the fluid escape structures revealing the relationship between the active tectonic with migration of fluids, to be used to assess the Submarine Geo-Hazard in the Sicily Channel. We identified two fluid escape fields whose genesis and evolution appear linked to the neotectonic and volcanic activities respectively, that represent the main controlling factors for the migration of fluid; considering the good correlation between pockmarks and the main identified fault systems. In conclusion, our results suggest that the degassing of fluids in this region is rooted at depth, and is mainly aligned with the NW-SE dip/strike slip fault systems, repeatedly reactivated, and linked to the volcanic activity. View publication