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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.

The Ionian Calabrian and Apulian margins are severely incised by a dense network of submarine canyon systems, that have formed in response to ongoing km-scale uplift of Calabria over the last ca. 1Ma. Despite their young age (Pleistocene) they incise the continental shelf and slope over lengths of tens of kilometres, with thalwegs up to 2 km wide, walls higher than 200m and headwalls, that can extend over more than 50 km.Some of the canyon headwalls are very close to the coastline and in some cases, retrogressive features are observed from morphology and sub-bottom observations, representing a potential hazard for population and coastal infrastructures. Some of the canyons are isolated, others form hierarchic systems with five or more canyons merging into dendritic (cauliflower) systems that may or may not be connected to onshore drainage networks. They exhibit different characteristics in terms of headwall geometry, profile concavity and sinuosity.We present new information on their geomorphic attributes to gain new understanding about the dynamic and evolution of the different canyon systems in the last 1Ma. In addition, we aim at extracting information regarding the grain size and sediment type from vintage backscatter geophysical data and subbottom data, to analyse canyon headwall enlargement and their erosive activity. The overall purpose of my study is to bring new insights about the inception and evolution of the different canyon systems in relation to tectonic and sea level changes and thus be able to assess the potential geohazards that retrogressive canyon headwalls may represent today for coastal areas and infrastructures.

To ensure environmental and public safety, critical facilities require rigorous seismic hazard analysis to define seismic input for their design. We consider the case of the Trans Adriatic Pipeline (TAP), which is a pipeline that transports natural gas from the Caspian Sea to southern Italy, crossing active faults and areas characterized by high seismicity levels. For this pipeline, we develop a Probabilistic Seismic Hazard Assessment (PSHA) for the broader area, and, for the selected critical sites, we perform deterministic seismic hazard assessment (DSHA), by calculating shaking scenarios that account for the physics of the source, propagation, and site effects. This paper presents a DSHA for a compressor station located at Fier, along the Albanian coastal region. Considering the location of the most hazardous faults in the study site, revealed by the PSHA disaggregation, we model the ground motion for two different scenarios to simulate the worst-case scenario for this compressor station. We compute broadband waveforms for receivers on soft soils by applying specific transfer functions estimated from the available geotechnical data for the Fier area. The simulations reproduce the variability observed in the ground motion recorded in the near-earthquake source. The vertical ground motion is strong for receivers placed above the rupture areas and should not be ignored in seismic designs; furthermore, our vertical simulations reproduce the displacement and the static offset of the ground motion highlighted in recent studies. This observation confirms the importance of the DSHA analysis in defining the expected pipeline damage functions and permanent soil deformations.

The design of critical facilities needs a targeted computation of the expected ground motion levels. The Trans Adriatic Pipeline (TAP) is the pipeline that transports natural gas from the Greek-Turkish border, through Greece and Albania, to Italy. We present here the probabilistic seismic hazard analysis (PSHA) that we performed for this facility, and the deaggregation of the results, aiming to identify the dominant seismic sources for a selected site along the Albanian coast, where one of the two main compressor stations is located. PSHA is based on an articulated logic tree of twenty branches, consisting of two models for source, seismicity, estimation of the maximum magnitude, and ground motion. The area with the highest hazard occurs along the Adriatic coast of Albania (PGA between 0.8 and 0.9 g on rock for a return period of 2475 years), while strong ground motions are also expected to the north of Thessaloniki, Kavala, in the southern Alexandroupolis area, as well as at the border between Greece and Turkey. The earthquakes contributing most to the hazard of the test site at high and low frequencies (1 and 5 Hz) and the corresponding design events for the TAP infrastructure have been identified as local quakes with MW 6.6 and 6.0, respectively.

19 pages, 13 figures, 1 table, supplementary material https://doi.org/10.1016/j.margeo.2022.106739.-- Seismic reflection and bathymetric data collected during the MARLBORO and SARAS cruises are stored at SISMER repository (https://doi.org/10.17600/11480100, https://doi.org/10.17600/12450090, and https://campagnes.flotteoceanographique.fr/campagnes/12000010). Landslide parameters for MTDs mapped during this study are given in the appendix., Earthquakes are the most commonly cited cause of offshore slope failure, followed by high sedimentation rates and ensuing pore pressure build-up. In the South Alboran Sea, the moderate seismicity (Mw = 6.4) of the strike-slip Al Idrissi Fault Zone does not appear to control directly the landslides distribution. To provide a preliminary geohazard assessment, we characterized the spatial distribution, the volume and the ages of the submarine landslides from multibeam and seismic reflection data in the southern part of the Alboran Sea. Since the Quaternary numerous submarine landslide processes have affected the marine sedimentary cover with volumes of the mass transport deposits (MTD) estimated between 0.01 and 15 km3. West of the Al Idrissi Fault Zone, along the South Alboran Ridge's northern flank, the distribution of the MTD follows the SW-NE bank and ridge trend that correlates with blind thrusts and folds covered by a plastered contourite drift. A pockmark field, related to fluid escape, is visible near landslide scars where the contourite drift is relatively thicker. In this area, landslide scars occur on variable slopes (2–24°) and their associated MTDs show variable decompacted volumes (0.01-10 km3). East of the Al Idrissi Fault Zone, between the Alboran Ridge and the Pytheas Bank, the mapped MTDs have uneven volume. The smaller ones (10°), whereas those of the largest ones (3–15 km3) occur on gentler slopes (, This work was funded by the French programs Actions Marges, Défi Risques Naturels CNRS-IRD (MITI-ALARM) and UPMC-Emergence (ALARM project), the ALBAMAR JCJC ANR-17-03CE-0004, the EUROFLEETS program (FP7/2007-2013; n°228344), project FICTS-2011-03-01. Seismic reflection data were processed using the Seismic UNIX SU and Geovecteur© software. The processed seismic data were interpreted using Kingdom IHS Suite© software. This work also benefited from the DAMAGE (AEI/FEDER CGL2016-80687-R) and FAUCES (Ref CTM2015-65461-C2-R; MINCIU/FEDER) Projects financed by “Ministerio de Economía y Competitividad y al Fondo Europeo de Desarrollo Regional” (FEDER). This work acknowledges the ‘Severo Ochoa Centre of Excellence’ accreditation of ICM-CSIC (CEX2019-000928-S

This research has been funding by the Spanish projects: DAMAGE ( CGL2016-80687-RAEI/FEDER ) and FAUCES ( CTM2015-65461-C2-1-R ); and the Junta de Andalucía projects: RNM-148 (AGORA) P18-RT-3275 and PAPEL ( B-RNM-301-UGR18 ), We thank the UTM-CSIC technicians and the crew of the RV Sarmiento de Gamboa for their help in collecting data. We are grateful for the multibeam data we received from the Secretaria General de Pesca of the Ministry of Agriculture, Fisheries and Food (Spain). We also thank IHS for providing the Kingdom Suite™ licence. This work acknowledges to IGCP 640 - S4LIDE (Significance of Modern and Ancient Submarine Slope LandSLIDEs), and to the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S)., We present a multidisciplinary study of morphology, stratigraphy, sedimentology, tectonic structure, and physical oceanography to report that the complex geomorphology of the Palomares continental margin and adjacent Algerian abyssal plain (i.e., Gulf of Vera, Western Mediterranean), is the result of the sedimentary response to the Aguilas Arc continental tectonic indentation in the Eurasian–Africa plate collision. The indentation is imprinted on the basement of the margin with elongated metamorphic antiforms that are pierced by igneous bodies, and synforms that accommodate the deformation and create a complex physiography. The basement is partially covered by Upper Miocene deposits sealed by the regional Messinian Erosive Surface characterized by palaeocanyons that carve the modern margin. These deposits and outcropping basement highs are then covered and shaped by Plio-Quaternary contourites formed under the action of the Light Intermediate and Dense Deep Mediterranean bottom currents. Even though bottom currents are responsible for the primary sedimentation that shapes the margin, 97% of this region's seafloor is affected by mass-movements that modified contourite sediments by eroding, deforming, faulting, sliding, and depositing sediments. Mass-movement processes have resulted in the formation of recurrent mass-flow deposits, an enlargement of the submarine canyons and gully incisions, and basin-scale gravitational slides spreading above the Messinian Salinity Crisis salt layer. The Polopo, Aguilas and Gata slides are characterized by an extensional upslope domain that shapes the continental margin, and by a downslope contractional domain that shapes the abyssal plain with diapirs piercing (hemi)pelagites/sheet-like turbidites creating a seafloor dotted by numerous crests. The mass movements were mostly triggered by the interplay of the continental tectonic indentation of the Aguilas Arc with sedimentological factors over time. The indentation, which involves the progressively southeastward tectonic tilting of the whole land-sea region, likely generated a quasi-continuous oversteepening of the entire margin, thus reducing the stability of the contourites. In addition, tectonic tilting and subsidence of the abyssal plain favoured the flow of the underlying Messinian Salinity Crisis salt layer, contributing to the gravitational instability of the overlying sediments over large areas of the margin and abyssal plain., DAMAGE CGL2016-80687-RAEI, FAUCES CTM2015-65461-C2-1-R, PAPEL B-RNM-301-UGR18, UTM-CSIC, Indian Health Service CEX2019-000928-S, European Regional Development Fund, Junta de Andalucía P18-RT-3275, RNM-148, Ministerio de Agricultura, Pesca y Alimentación

17 pages, 9 figures, 1 table, Submarine canyons are deep, large-scale incisions that occur on the continental shelf and slope of all ocean margins. These landforms serve as preferential particle-transport conduits that connect the coastal zone with the deep-sea. Canyons have been studied for decades and are among the most iconic submarine geomorphic features. Advances in marine technology are increasingly providing new understanding of the physical and biological processes that take place in canyons, which are also notoriously affected by the impact of anthropogenic activities. In this article we describe the main geomorphic characteristics of submarine canyons and synthesize the past and current knowledge on their formation, evolution, global distribution and hydrodynamical and ecological significance.

Introduzione all'Atlante dei lineamenti di pericolosità geologica dei mari italiani, alla legenda ed ai criteri interpretativi

Mud volcanoes (MVs) have been found in various geological settings on passive and active margins but are mostly known from collision zones on Earth. Mud volcanoes are well known to occur on land (e.g. in Azerbaijan), where at least 1000 MVs have been counted. The amount of submarine MVs is believed to be much larger and recent improvements in seafloor mapping led to the discovery of many MVs in all oceans. To contribute to the knowledge of submarine MVs, in particular the internal structure across Venere MV, we conducted a multi-geophysical imaging approach using high resolution multibeam bathymetry, (constraining seafloor expressions), multichannel, and wide-angle seismic data (constraining the internal structure and P-wave velocity distribution). Venere MV is located at the southern rim of the Crotone forearc basin of the Calabrian arc, offshore southern Italy, in a water depth of ~1500 m. The dimension of Venere MV from its bathymetric expression is ~10 km in the EW- and ~7 km in the NS-direction. Two circular cones of ~100 m elevation and ~1.5 km diameter are located in the center of Venere MV. The upper 200 m below the seafloor (bsf) consist of layers with seismic P-wave velocities gradually increasing from 1.53 to 1.7 km/s (sub-) parallel to the seafloor. A prominent reflection ~200 m bsf and a sudden increase of seismic P-wave velocities from 1.7 to 1.8 km/s mark a change with depth in the internal structure, where reflections dip, and seismic P-wave velocities laterally decrease towards the center of Venere MV. The MCS as well as seismic P-wave velocity structure indicate two separate feeder conduits of the two center cones of Venere MV. However, we do not map the roots of the MV, which are at depths beyond our data resolution. Reduced reflectivity occurs ~4 km across the center of the MV 200 m bsf and downwards. We mapped the chaotic reflections of the acoustic basement in depths varying from 500 m to 800 m bsf. Reduced reflectivity of the acoustic basement occurs beneath the center of the MV as well. Mapping of the fault system leads to the subseafloor dimension of Venere MV that exceeds its seafloor dimension by the factor of two.

Large-scale submarine gravitational land movements involving even more than 1,000 m thick sedimentary successions are known as megalandslides. We prove the existence of large-scale gravitational phenomena off the Crotone Basin, a forearc basin located on the Ionian side of Calabria (southern Italy), by seismic, morpho-bathymetric and well data. Our study reveals that the Crotone Megalandslide started moving between Late Zanclean and Early Piacenzian and was triggered by a contractional tectonic event leading to the basin inversion. Seaward gliding of the megalandslide continued until roughly Late Gelasian, and then resumed since Middle Pleistocene with a modest rate. Interestingly, the onshore part of the basin does not show a gravity-driven deformation comparable to that observed in the marine area, and this peculiar evidence allows some speculations on the origin of the megalandslide.

During the last 0.45 Ma, the Crotone Basin, a forearc basin located on the Ionian side of Calabria, southern Italy, experienced a phase of uplift that persists today. The transition from subsidence to uplift occurred close to the Marine Isotope Stage (MIS) 11 (ca. 0.4 Ma). The subsequent progressive emergence of the area was punctuated by several marine transgressions linked to high-frequency, high-magnitude glacio-eustatic changes, which are recorded as coastal terraces. These high-frequency sequences show a variable stacking pattern due to the interplay between glacio-eustasy, uplift and local physiography. In particular, a progressive SE-ward migration of the shoreline is documented in the study area since MIS 11. This trend was enhanced during the MIS 5.5 to MIS 2 time interval, due to the combined effect of uplift and lowering glacio-eustatic sea level until the Last Glacial Maximum. Moreover, the regional uplift also led to a physiographic change from relatively low-gradient to high-gradient settings between MIS 7.1 and MIS 5.5. A comparison between the late Quaternary geological record of the Crotone Basin and that of other basins is crucial to improve the present knowledge on past sea levels related to MISs. This ultimately will help to better understand the Holocene sea-level history and the human contribution to sea-level change, in order to predict future scenarios.

The Crotone Basin is a Neogene-Quaternary depocenter developed along the Ionian margin of Calabria, southern Italy. The basin opening was concomitant with the onset of spreading of the Tyrrhenian backarc Basin during late Serravallian and the subduction of the Ionian lithosphere below the Calabrian Arc. The adoption of modern sequence stratigraphic principles to subdivide the basin fill into stratigraphic sequences of different rank, bounded by subaerial unconformities, has allowed cycles of creation and loss of accommodation mainly related to tectonics to be recognized. In particular, an alternation between phases of basin subsidence, concomitant with spreading of the Tyrrhenian backarc Basin and forward migration of the Arc, and phases of compressional or transpressional tectonics, accompanied by basin uplift and stopping of Arc migration, are well recognizable in the basin fill, in particular for the late Messinian to late Pleistocene part of the succession. The present study highlights the effectiveness of the sequence stratigraphic method in basin analysis to decipher the effects of large-scale tectonic events on sedimentation and ultimately to reconstruct the geodynamic evolution of the central Mediterranean.

Amblas, David ... et al.-- 22 pages, 8 figures, 1 table, Submarine canyons are deep incisions observed along most of the world’s continental margins. Their topographic relief is as dramatic as that of any canyon or river valley on land but is hidden beneath the surface of the ocean. Our knowledge of canyons has therefore come primarily from remote sensing and sampling, and has involved contributions from various oceanographic disciplines. Canyons are a critical link between coastal and shelf waters and abyssal depths; water masses, sediment, nutrients, and even litter and pollutants are carried through them. Advances in technology continue to provide new insights into canyon environments by pushing the frontier of deep marine observations and measurements. In this chapter we describe the main geomorphic features of submarine canyons and what is known about their formation and the processes that shape them. We also consider submarine gullies, which are small valleys commonly found within or alongside submarine canyons on the continental slope and may represent an incipient stage of canyon development, This work was supported by the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 658358 (D. Amblas)

Three regional unconformity surfaces typify the Plio-Pleistocene fill of the onshore to offshore basins of the Calabrian Arc, an arcuate terrane migrating to the SE above the NW subducting Ionian lithosphere, between the southern Apennines and Sicily. These unconformity surfaces formed in the mid-Pliocene (late Zanclean to early Piacenzian), the early Pleistocene (intra-Gelasian) and the mid-Pleistocene (late Calabrian). Their expression varies significantly across the area, so that from one to three unconformities may be recognized within any given basin. Several lines of evidence suggest that the spatially variable development of the unconformities across the Arc records interruptions of subsidence by phases of uplift and deformation, related to the extent and nature of successive tectonic events linked to episodic subduction zone retreat and slab fragmentation during the Plio-Pleistocene interval. In particular, the mid-Pliocene unconformity is associated with uplift and deformation on the Ionian flank of the Calabrian Arc that interrupted a phase of basin subsidence coeval with opening of the Vavilov back-arc basin, and may record either interference of the Arc with the Apulian microplate, or an episode of out-of-sequence tectonic thickening within` the advancing accretionary wedge. The two Pleistocene unconformities bracket a phase of basin collapse in northern Calabria that coincides with the ultra-fast opening of the Marsili backarc basin, and are associated with uplift and contractional–transpressional deformation that record interference of the subducting slab with adjacent microplates. The recognition of a synchronous development of unconformities in the Calabrian basins provides key references for further studies of the geodynamic evolution of the central Mediterranean.

‘Cold’ seeps (or cold vents) are seafloor manifestations of fluid migration through sediments from the subsurface to the seabed and into the water column, and may reach the atmosphere. They are an important but not fully understood process in our oceans that has important repercussions on human society and on the climate. Modern sonar systems can obtain seafloor images of cold seep features from tens to thousands of meters wide with metric resolution, providing key information on the formation and evolution of the various seabed expressions of cold seeps. In this chapter we attempt to address cold seep systems with an emphasis on their origin, evolution, form, and occurrence, approaching them primarily from their morphologies and the acoustic character of the seafloor and near bottom erupted sediments. We address morphological characteristics of mud volcanoes, pockmarks, carbonate-related structures including MDAC, AOM and giant carbonate mounds and ridges, offering various examples mainly from recent discoveries in Mediterranean region which are among the most spectacular and most frequently cited examples. Detailed focus on topics such as acoustic backscatter, brine pools, etc. have been described in separate gray boxes of text with the aim to highlight their particular significance. Finally, gaps in knowledge and key research questions on cold seep studies have been outlined with the aim of orienting young researchers and students towards those topics that deserve the highest attention as they are still unresolved., Istituto Nazionale di Oceanografia e di Geofisica Sperimentale, Italia, FREMER Laboratoire Aléas géologiques et Dynamique Sédimentaire Centre Bretagne, Francia, Área de Geología Marina, Instituto Geológico y Minero de España, España, Lyngby Marine Geophysical Research, Países Bajos

Mud volcanoes (MVs) are abundant along the eastern Mediterranean subduction zones, recording mud breccia extrusion over long timescales (106 years), but to date relatively few have been recognised in the northern Ionian Sea on the Calabrian accretionary prism (CAP). In the present study, the seafloor distribution and recent activity of MVs is investigated across a 35,600 km2 sector of the CAP using a regional acoustic dataset (multibeam bathymetric and backscatter imagery, integrated with subbottom profiles) locally ground-truthed by sediment cores. A total of 54 MVs are identified across water depths of 150–2,750 m using up to four geophysical criteria: distinctive morphology, high backscatter, unstratified subbottom facies and, in one case, a hydroacoustic flare. Fourteen MVs are identified from 3–4 criteria, of which five have been previously proven by cores containing mud breccia beneath up to 1.6 m of hemipelagic sediments (Madonna dello Ionio MVs 1–3, Pythagoras MV and the newly named Sartori MV), while nine others are identified for the first time (Athena, Catanzaro, Cerere, Diana, Giunone, Minerva, ‘right foot’, Venere 1 and 2). Forty other as yet unnamed MVs are inferred from 1–2 geophysical criteria (three from distinctive morphology alone). All but one possible MV lie on the inner plateau of the CAP, landwards of the Calabrian Escarpment in a zone up to 120 km wide that includes the inner pre-Messinian wedge and the fore-arc basins, where they are interpreted to record the ascent from depth of overpressured fluids that interacted with tectonic structures and with evaporitic or shale seals within the fore-arc basins. The rise of fluids may have been triggered by post-Messinian out-of-sequence tectonism that affected the entire pre-Messinian prism, but Plio-Quaternary sedimentation rates and depositional styles support the inference that significant mud volcanism has taken place only on the inner plateau. Sedimentation rates across the CAP applied to a 12 khz sonar detection depth of 225 cm imply that all MVs with backscatter signatures (50 of 54) have erupted mud breccias within the last 56 ka, and within the last 12.5 ka in the fore-arc basins. Ages of eruption estimated from the depth of cored mud breccias at five MVs, and a seismo-stratigraphic relationship at a sixth, indicate episodes at the last glacial maximum ca. 20 ka BP and during the postglacial period. Eruptive episodes within the Calabrian MV province constitute recurrent geohazards, separated by longer periods of quiescent (subdued) fluid seepage that are likely to support gas hydrate formation and chemosynthetic ecosystems.

The northern Calabria along the southeastern coast of Italy provides a favorable setting in which to study complete transects from continental to deep-marine environments. The present northern Ionian Calabrian Basin is a wedge-top basin within the modern foreland-basin system of southern Italy. The Ionian margin of northern Calabria consists of a moderately developed fluvial systems, the Crati and Neto rivers, and diverse smaller coastal drainages draining both the Calabria continental block (i.e., Sila Massif) and the southern Apennines thrust belt (i.e., Pollino Massif). The main-channel sand of the Crati and Neto rivers is quartzofeldspathic with abundant metamorphic and plutonic lithic fragments (granodiorite, granite, gneiss, phyllite and sedimentary lithic fragments). Sedimentary lithic fragments were derived from Jurassic sedimentary successions of the Longobucco Group. The mud samples contain mostly phyllosilicates, quartz, calcite, feldspars and dolomite. Traces of gypsum are present in some samples. The I–S mixed layers, 10 A-minerals (illite and micas), chlorite and kaolinite are the most abundant phyllosilicates, whereas smectite and chlorite/smectite mixed layers are in small amounts. The geochemical signatures of the muds reflect a provenance characterized by both felsic and mafic rocks with a significant input from carbonate rocks. Furthermore, the degree of source-area weathering was most probably of low intensity rather than moderately intense because CIA values for the studied mud samples are low. Extrapolation of the mean erosion budget from 1 to 25 Ma suggests that at least 5 to 8 km of crust have been removed from the Calabrian orogenic belt and deposited in the marine basins. The Calabrian microplate played an important role in the dynamic evolution of southern Italian fossil and modern basins, representing the key tectonic element of the entire orogenic belt.

We report the detection of mound-like landforms interpreted as mud volcanoes within Firsoff crater, in the Arabia Terra region of Mars. The mounds stratigraphically overlie layered deposits within the crater, which consist of high albedo well-bedded deposits disrupted in meter-sized polygons. Hundreds of mounds are observed on the crater floor, as isolated or composite subcircular cones 100–500 m in diameter and tens of meters high. More than one third of the mounds (35%) have subcircular depressions 5–39 m in diameter at their apices that we interpret as vents. The mounds consist of meter-sized boulders of high albedo, embedded in an apparently finer-grained unit; we interpret these deposits as mud volcanic breccia, containing boulders of reworked light-toned layered deposits carried upward from deeper portions of the succession. The mounds are mainly located near the rim-bordering faults and in places aligned with fractures, suggesting subsurface pathways for fluid migration. The mounds are interpreted as fossil mud volcanoes, recording the upward migration of overpressured fluids through the crater infill from deeper crustal sources, localized by impact-related faults. The geological conditions and processes that might have controlled sedimentary expulsion on Mars are discussed. Mud volcanism has most of its controls in the subsurface. As a consequence, subsurface fluid flow processes could be expected in other craters within Arabia Terra and are less likely in higher, adjacent highland terrains.

CHIRP subbottom profiles performed on the Ionian Calabrian margin, southern Italy, allow the recognition of an irregular step-like seabed topography and a marked variability in the geometry of the post-Last Glacial Maximum (LGM) transgressive wave ravinement surface (WRS). The WRS truncates an older unit showing locally an opaque seismic character, and displays both concave-up and concave-down profiles in any dip section and a local stepped geometry, with gradients between 1° and > 20°. A younger unit, characterized by high-amplitude reflectors onlapping or draping the WRS, is interpreted as a sediment wedge accumulated during the post-LGM glacio-eustatic rise. The WRS crops out forming steep slopes up to 12°, which are interpreted as relicts of palaeo-coastal cliffs generated by wave action during relative sea-level rise. In particular, the deeper slope is locally exposed between ca. 75 and 100 m water depth, corresponding closely with the depth range of melt-water pulse (MWP) 1A (14.3–14.0 ka BP), assuming no subsidence or uplift, and its generation is inferred to be related to this event. A transgressive model for high-gradient settings and stepped sea-level rise is proposed. Coastal cliffs develop and retreat due to wave erosion during phases of slow relative sea-level rise. During phases of very high rate of relative sea-level rise, coinciding with melt-water pulses, cliffs tend to be overstepped, drowned and not completely eroded by the WRS. Such a ‘cliff overstep’ transgressive model is the equivalent in high-gradient settings of the ‘in-place drowning’ model, developed for low-gradient shelves. The present model may be effective in reconstructing stepped sea-level rises and the evolution of shelf areas during Late Quaternary time.

The Quaternary development offshore the Faroe Islands has been studied using high-resolution seismic and core data from the R/V DANA 2000 cruise and previous cruises. Several glacial-related features and deposits are observed, all bearing witness to former extensive glaciations of the Faroe area. On the shelves, overlaying a mid-Pleistocene glacial erosional surface, glacial and glacimarine deposits form a sheet geometry interrupted by ridges of sediment that are likely to represent ice-front deposits. An iceberg turbate north of the Faroe Islands provides evidence of large-scale drift of ultra-deep draft (>600 m) icebergs in the Nordic Seas at pre-Weichselian glacial stage(s). Marginal and transverse troughs found on the eastern and western shelf are suggested to have formed during the same glacial period(s) as the iceberg turbate. Iceberg plough-marks and abundant ice rafted material of non-Faroese origin, together with the relict moraine ridges encircling the Faroe Islands at around the 100 and 200 m water depth contours, indicate that the outer shelf was probably ice free during the Weichselian ice age. On the slopes and basinal parts, the formation of fine-grained contourites was favoured during (Weichselian) glacial stages when bottom currents were reduced. Sediment overloading during these glacial stages resulted in repeated slope instability, causing mass failures of the contourite deposits.

Based on studies of sediment accumulations deposited from-and erode by-alongslope flowing ocean currents on the European continental margin from Porcupine (Ireland) to Lofoten (Norway), the evolution of the Cenozoic paleocirculation was reconstructed as part of the STRATAGEM project. There is evidence of ocean current-controlled erosion and deposition in the Rockall Trough, in the Faeroe-Shetland Channel and on the Voring Plateau since the late Eocene, although the circulation pattern remains ambiguous. The late Palaeogene flow in the Rockall Trough was almost probably driven by southerly-derived Tethyan Outflow Water. The extent and strength of any northerly-derived flow is uncertain. From the early Neogene (early-mid-Miocene), there was a massive regional expansion of contourite drift development both in the North Atlantic and in the Norwegian-Greenland Sea. This was most probably related to the development of the Faroe Conduit, the opening of the Fram Strait and the general subsidence of the Greenland-Scotland Ridge. These may have combined to cause a considerable acceleration in the exchange and overflow of deep waters between the Arctic and Atlantic Oceans. An early late Neogene (late early Pliocene) regional erosional event has been ascribed to a vigorous pulse of bottom-current activity, most probably the result of a global reorganisation of ocean currents associated with the closure of the Central American Seaway. During the late Neogene, contourites and sediment drifts developed in deep-water basins, between units of glacigenic sediments as well as infill of several paleo-slide scars. These sediments were derived from areas of bottom-current erosion as well as from the development of Plio-Pleistocene prograding sediment wedges, incorporating the extensive sediment supply derived from shelf-wide ice sheets. Presently a profound winnowing prevails along the shelf and upper slope due to the inflowing currents of Atlantic water. Depocentres of sediments derived from the winnowing are located (locally) in lower slope embayments and in slide scars.

The North Atlantic margins are archetypally passive, yet they have experienced post-rift vertical movements of up to kilometre scale. The Cenozoic history of such movements along the NW European margin, from Ireland to mid-Norway, is examined by integrating published analyses of uplift and subsidence with higher resolution tectono-stratigraphic indicators of relative movements (including results from the STRATAGEM project). Three episodes of epeirogenic movement are identified, in the early, mid- and late Cenozoic, distinct from at least one phase of compressive tectonism. Two forms of epeirogenic movement are recognised, referred to as tilting (coeval subsidence and uplift, rotations

Acoustic data and sediment cores collected from the Storegga Slide and its adjacent slide flanks, i.e. the Voring Plateau to the north and the North Sea Fan to the south, have been used to study the Late Cenozoic glacial history and geological development of this region. Age constrains obtained from the investigated cores show that the Fennoscandian Ice Sheet reached the shelf edge during Marine Isotope Stages (MIS) 12, 10, 8, 6 and 2. Ice sheet fluctuations within each glaciation might have occurred, as is evidenced for the Last Glacial Maximum (MIS 2). The first extensive ice advance is identified in the Early Pleistocene, at c. 1.1 Ma; however, between 2.6 and 0.5 Ma the ice sheets were largely restricted to the fjords and inner shelf. During each glacial maximum, glacigenic debris flows (GDFs) transported basal till, deposited at the shelf edge, into the deep sea along the entire studied margin. The most voluminous GDF sequences are found on the southern Storegga Slide flank (North Sea Fan), where the individual flows are found as far as 500 km from the shelf edge. On the Voring Plateau glacimarine/hemipelagic sedimentation has dominated the last c. 250,000 yr. During MIS 2 such sediments were rapidly deposited, covering the upper-slope-limited GDF units in this region. Between c. 15,700 and 15,000 14C yr BP, i.e. during the last deglaciation of the Norwegian margin, a presumed meltwater plume, released from the disintegrating Norwegian Channel Ice Stream, transported and rapidly deposited up to 20 m of fine-grained sediments in the region north of the North Sea Fan. The rapid deposition of large volumes of GDFs, glacimarine and meltwater related sediments might have influenced the stability of the slope sediments in the studied region, promoting conditions favorable for failure. Furthermore, these high sedimentation rates also partly account for the high subsidence rates observed on the Norwegian continental margin in the Late Cenozoic.

International audience; Existing knowledge on the distribution of mud volcanoes (MVs) and other significant fluid/free gas-venting features (mud cones, mud pies, mud-brine pools, mud carbonate cones, gas chimneys and, in some cases, pockmark fields) discovered on the seafloor of the Mediterranean Sea and in the nearby Gulf of Cadiz has been compiled using regional geophysical information (including multibeam coverage of most deepwater areas). The resulting dataset comprises both features proven from geological sampling, or in situ observations, and many previously unrecognized MVs inferred from geophysical evidence. The synthesis reveals that MVs clearly have non-random distributions that correspond to two main geodynamic settings: (1) the vast majority occur along the various tectono-sedimentary accretionary wedges of the Africa-Eurasia subduction zone, particularly in the central and eastern Mediterranean basins (external Calabrian Arc, Mediterranean Ridge, Florence Rise) but also along its westernmost boundary in the Gulf of Cadiz; (2) other MVs characterize thick depocentres along parts of the Mesozoic passive continental margins that border Africa from eastern Tunisia to the Levantine coasts, particularly off Egypt and, locally, within some areas of the western Mediterranean back-arc basins. Meaningfully accounting for MV distribution necessitates evidence of overpressured fluids and mud-rich layers. In addition, cross-correlations between MVs and other GIS-based data, such as maps of the Messinian evaporite basins and/or active (or recently active) tectonic trends, stress the importance of assessing geological control in terms of the presence, or not, of thick seals and potential conduits. It is contended that new MV discoveries may be expected in the study region, particularly along the southern Ionian Sea continental margins.

International audience; The central Nile Deep-Sea Fan contains a broad area of seabed destabilisation in association with fluid seepage: slope-parallel sediment undulations are associated with multibeam high-backscatter patches (HBPs) related to authigenic carbonates. During the 2011 APINIL campaign, a deep-towed sidescan and profiling system (SAR) was used to acquire high-resolution data along three transects across water depths of 1,700-2,650 m. Three seabed domains are distinguished, all developed within stratified sediments overlying mass-transport deposits (MTDs). Upslope of the undulations (

The Ionian margins of Calabria are affected by repeated sediment failures, recorded by slide scars at seabed and stacked slide deposits. We present a reconstruction of the geometry and dynamics of one of the largest seabed features, the Assi failure on the relatively steep slope off southern Calabria, and use it as input to numerical modeling to evaluate the potential tsunamigenic hazard. The Assi failure is up to 6 km wide and at least 18 km long, and involved the displacement of ca. 2 km3 of sediment, inferred to have taken place within the last 4,000 years in two main phases. The first and larger phase is used as input to the tsunami modeling, on the assumption that the slide moved in a single step as a coherent mass of 1.85 km3, in order to evaluate the most disruptive possible consequences. The results indicate that within 8 minutes, waves just over 1 m in height affect the southern Calabrian coast between Monasterace and Roccella Jonica, where their capacity to cause damage could be amplified in small harbours. This shows that tsunamis represent a hazard for Ionian coastal areas, and calls for accurate monitoring and further study.

International audience; On the central Nile deep-sea fan, stratified sediments overlying mass-transport deposits (MTDs) are deformed into slope-parallel seabed undulations associated with fluid seepage. The western part of this system, in water depths of 1,950-2,250 m, is examined using multi-frequency data from hull-mounted and deep-towed swath/profiling systems. Sub-bottom profiles show sub-vertical fluid pipes that terminate both at and below seabed, and gas signatures along fault planes bounding the undulations. Fluid seepage is recorded by high- to intermediate-backscatter patches (HBPs, IBPs) that differ in appearance on multibeam imagery (30 kHz, ≤3 m penetration) and sidescan swaths (170/190 kHz

High resolution, single-channel seismic sparker profiles across the Akademichesky Ridge, an intra-basin structural high in Lake Baikal (Russia), reveal the presence of small sediment mounds and intervening moats in the upper part of the sedimentary cover. Such features interrupt the generally uniform and even acoustic facies and are not consistent with the hemipelagic sedimentation, which is expected on such an isolated high and which would produce a uniform sediment drape over bottom irregularities. The influence of turbidity currents is excluded since the ridge is an isolated high elevated more than 600-1000 m above adjacent basins. The mounded seismic facies, including migrating sediment waves and non-depositional/erosional incisions, strongly suggest that sediment accumulation was controlled by bottom-current activity. We interpret the mounds as small-scale (< few tens of km2 in area) lacustrine drifts. Four basic types of geometry are identified: 1) slope-plastered patch sheets; 2) patch drifts; 3) confined drifts; 4) fault-controlled drifts. The general asymmetry in the sedimentary cover of the ridge, showing thicker deposits on the NW flank, and the common location of patch drifts on the northeast side of small basement knolls indicate that deposition took preferentially place at the lee sides of obstacles in a current flowing northward or sub-parallel to the main contours. Deep-water circulation in the ridge area is not known in detail, but there are indications that relatively cold saline water masses are presently flowing out of the Central Basin and plunging into the deep parts of the North Basin across the ridge, a process that appears to be driven mainly by small differences in salinity. We infer that the process responsible for the observed bottom-current-controlled sedimentary features has to be sought in these large-scale water-mass movements and their past equivalents. The age of the onset of the bottom-current-controlled sedimentation, based on an average sedimentation rate of 4.0 cm/ky, is roughly estimated to be as least as old as 3.5 Ma, which is generally regarded as the age of the onset of the last major tectonic pulse of rift basin development in the Baikal region.

New high-resolution seismic reflection data from the central part of Lake Baikal provide new insight into the structure and stratigraphy of Academician Ridge, a large intra-rift accommodation zone separating the Central and North Baikal basins. Four seismic packages are distinguished above the basement: a thin top-of-basement unit; seismic-stratigraphic unit X; seismic-stratigraphic unit?A; and seismic-stratigraphic unit?B. Units A and B were cored on selected key locations. The four packages are correlated with a series of deposits exposed on the nearby western shores: the Ularyar Sequence (Oligocene); the Tagay Sequence (Lower to Middle Miocene); the Sasa Sequence (Upper Miocene to Lower Pliocene); the Kharantsy Sequence (Upper Pliocene); and the Nyurga Sequence (Lower Pleistocene). Based on stratal relationships, sedimentary geometries, distribution patterns and principal morphostructural elements – both onshore and offshore – we propose a new palaeogeographic evolution model for the area. In this model progressive tectonic subsidence of the Baikal basins and successive pulses of uplift of various segments of the rift margins lead to: (a) formation of the ridge as a structural and morphological feature separating the Central and North Baikal basins during the Middle to Late Miocene; (b) gradual flooding of the main parts of the ridge and establishment of a lacustrine connection between the two rift basins during the Late Miocene; and (c) total submergence of the top parts of the crest of the ridge during the latest Pleistocene. This new model helps to better constrain numerous phases in the structural evolution of the Baikal Rift, in which the Academician Ridge as an accommodation zone plays a crucial role.

Voluminous mass-transport deposits (MTD) have been identified on seismic profiles across the central Nile Deep-Sea Fan (NDSF). The youngest MTDs are buried under 30–100 m of well-stratified slope deposits that, in water depths of 1,800–2,600 m, are characterized by undulating reflectors correlated with slope-parallel seabed ridges and troughs. Seabed imagery shows that, in the western part of the central NDSF, short, arcuate undulations are associated with fluid venting (carbonate pavements, gas flares), while to the east, long, linear undulations have erosional furrows on their downslope flanks and fluid seeps are less common. Sub-bottom profiles suggest that the western undulations correspond to rotated fault-blocks above the buried MTDs, while those in the east are sediment waves generated by gravity flows. We suggest that fluids coming from dewatering of MTDs and/or from deeper layers generate overpressures along the boundary between MTDs and overlying fine-grained sediment, resulting in a slow downslope movement of the sediment cover and formation of tilted blocks separated by faults. Fluids can migrate to the seafloor, leading to the construction of carbonate pavements. Where the sediment cover stabilizes, sediment deposition by gravity flows may continue building sediment waves. These results suggest that complex processes may follow the emplacement of large MTDs, significantly impacting continental-slope evolution.

The Ionian margins of Calabria and Apulia (IMCA) have been affected by mass movements of varying style, scale and age. Here we present examples of seabed and subsurface features identified along more than 400 km of the IMCA from multibeam seabed imagery and subbottom profiles acquired by OGS since 2005. Four different types of mass movement phenomena are recognized with expression at seabed and in the shallow subsurface: (1) mass transport complexes (MTCs) within intra-slope basins, (2) isolated slide scars (ISS) along open slopes, (3) slope-parallel sediment undulations (SPSU) recording block-rotations linked to fluid migration, and (4) headwall and sidewall scarps (HSC) in submarine canyons. Preliminary analyses of sedimentary processes suggest that both open-slope failures capable of triggering tsunamis and retrogression of canyon headwalls within 1–3 km of the Calabrian coast represent potential geohazards for coastal populations and offshore infrastructures.

Mud volcanoes recently discovered on the offshore Calabrian Arc are investigated at two sites 60 km apart, in water depths of 1650--2300 m, using swath bathymetry, 2D&3D multichannel seismic and cores. The seabed and subsurface data provide information on their formation and functioning in relation to tectonic activity during the rapid Plio-Quaternary advance of the accretionary prism. Fore-arc extension and thrust-belt compression are seen to have involved two main phases of activity, separated by a regional unconformity recording a mid-Pliocene (3.5–3.0 Ma) tectonic reorganization. The two sites of mud volcanism lie in contrasting tectonic settings (inner fore-arc basin vs central fold-and-thrust belt) and record differing forms of seabed extrusive activity (twin mud cones and a caldera vs a broad mud pie). At both sites, subsurface data show that mud volcanism took place throughout the second tectonic phase, since the late Pliocene; differing forms of mud extrusion were accompanied by subsidence to form depressions beneath and within extrusive edifices up to 1.5 km thick. The basal subsidence depressions point to sources within the succession of thrusts underlying the inner to central Arc, consistent with microfossils within cored mud breccias from both sites that are derived from strata as old as Late Cretaceous. These results are argued to support a model of mud volcanism in which deeply-rooted fluid conduits drive a process of near-surface sediment mobilization. The onset of extrusive activity is inferred to have been triggered by the mid-Pliocene tectonic reorganization, the change in stress fields (which post-dates the migration of frontal compression across the area by >4 Ma) opening pathways for the release of overpressured fluids from deep within the accretionary prism. The rising fluids interacted with shallow (

Submarine hydrocarbon seeps are geologically driven "hotspots" of increased biological activity on the seabed. As part of the HERMES project, several sites of natural hydrocarbon seepage in the European seas were investigated in detail, including mud volcanoes and pockmarks, in study areas extending from the Nordic margin, to the Gulf of Cádiz, to the Mediterranean and Black seas. High-resolution seabed maps and the main properties of key seep sites are presented here. Individual seeps show ecosystem zonation related to the strength of the methane flux and distinct biogeochemical processes in surface sediments. A feature common to many seeps is the formation of authigenic carbonate constructions. These constructions exhibit various morphologies ranging from large pavements and fragmented slabs to chimneys and mushroom-shaped mounds, and they form hard substrates colonized by fixed fauna. Gas hydrate dissociation could contribute to sustain seep chemosynthetic communities over several thousand years following large gas-release events.

Anthropogenic trace metal concentrations were studied in sediments of the South Adriatic basin. This study shows that in some Anthropogenic trace metal concentrations were studied in sediments of the South Adriatic basin. This study shows that in some Mediterranean sedimentation systems, the anthropogenic trace metal contamination is affecting not only the coastal areas and continental shelf, but is transferred to some extent also in the adjacent continental slope and deep basin. Complex morphology and sedimentary processes are responsible for the spatial differences in trace metal concentrations between different sub-areas of the South Adriatic. Historical trace metal profiles show trends that were increasing in the 20 century and decreasing in the last 30 years.

Zn and Pb are well known for having a large anthropogenic component in the Adriatic Sea. These trace elements were measured along with OC and mud content in sediments to distinguish their trends among three sectors within the western Adriatic Sea (North, Central and South). The highest concentrations were found in the North within to the Po river prodelta. Discriminant analysis results showed the separation of the North from the Central and the South due to Zn, OC and mud content. Pb did not display a specific trend probably being more associated to the clay fraction of sediments.

Sediment transfer from the continental shelf to the deep basin is of great interest as it partially controls the morphological and architectural evolution of continental margins. Transfer of particles on the continental slope associates with processes of erosion and deposition that control the construction of typical features such as submarine canyons. Because they strongly erode the continental slope, canyons contribute significantly to its morphological evolution through time. However, a number of studies have evidenced submarine canyons that do not connect with sub‐aerial channelized systems, questioning their processes of formation and evolution. This study aims to better understand the processes of formation and evolution of six submarine canyons identified on the western margin of the Ligurian Basin and ten canyons systems on the Calabro-Ionian margin. From morphometric and structural analyses based respectively on bathymetric, seismic‐reflexion (24‐channel profiles) data, Chirp and SAR profiles we constrained the main morphometric characteristics (length, width, depth, slope gradient, sinuosity index), morphologic (architectural elements and configuration) of canyons, their downward evolution and we analyzed their internal structure in order to better understand their origin, construction mechanisms and evolution in relation with the regional geological context and their potentials subaerial systems., Les marges continentales, passives ou actives, sont la principale voie de transfert sédimentaire entre le plateau continental et le bassin océanique profond et les plaines abyssales. Les pentes continentales sont le siège de processus d’érosion/dépôt sous le contrôle de transfert de flux particulaires continentaux chenalisés par des structures érosives, telles que les canyons sous‐marins, puis redistribues à l’ensemble de la marge. Les canyons érodent fortement les pentes continentales et contribuent à l’évolution de leur morphologie au cours du temps. On retrouve cependant des canyons sous‐marins qui ne sont pas en relation avec la présence d’un réseau fluviatile. De ce fait, la formation et l’évolution des canyons sous‐marins sont encore peu comprises. Ce travail de thèse s’intéresse aux processus de formation et d’évolution de six canyons sous-marins sur la Marge Ouest du Bassin Ligure et à dix systèmes de canyons sur la Marge Calabro-Ionienne. Le but de cette étude est de contraindre les principales caractéristiques morphométriques (longueur, largeur, profondeur, inclinaison, sinuosité), morphologique (éléments architecturaux, configuration) des canyons, de caractériser leur évolution amont‐aval et d’analyser leur structure interne, afin de mieux comprendre l’origine des canyons sous‐marins, leurs mécanismes de construction et leur évolution au cours du temps en relation avec le contexte géologique régional et leurs potentiels bassins versants subaérien. Pour cela, une approche basée sur une analyse morpho-bathymétrique et géophysiques a été mise en œuvre à partir de relevés bathymétriques complets des marges, de profils de sismiques, de Chirp et de SAR.