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This is ISMAR contribution number 2014.-- 5 pages, 3 figures, The Tyrrhenian Basin is a region created by Neogene extensional tectonics related to slab rollback of the east-southeast–migrating Apennine subduction system, commonly believed to be actively underthrusting the Calabrian arc. A compilation of >12,000 km of multichannel seismic profiles, much of them recently collected or reprocessed, provided closer scrutiny and the mapping of previously undetected large compressive structures along the Tyrrhenian margin. This new finding suggests that Tyrrhenian Basin extension recently ceased. The ongoing compressional reorganization of the basin indicates a change of the regional stress field in the area, confirming that slab rollback is no longer a driving mechanism for regional kinematics, now dominated by the Africa-Eurasia lithospheric collision, We acknowledge the project FRAME (ref. CTM2015-71766-R) funded by the Spanish Ministry of Science, Innovation, and Universities for supporting the work in the Tyrrhenian Sea, With the funding support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI)

Seamounts are spectacular bathymetric features common within volcanic and tectonically active continental margins. During their lifecycles, they evolve through stages of construction and destruction. Seamount chains on the Southwest Iberian Margin are prone to instability and collapse due to regionally complex tectonism with moderate to high seismicity. In this work we investigate collapse episodes during the lifecycle of the tectonic Gorringe Bank (GB), the largest submarine seamount offshore European margins, based on recurrence patterns of MTDs on the active thrust flank. Eight MTDs with relevant expression on the seismic data were analysed, four of estimated Miocene age and four on a Pliocene-Quarternary interval. Miocene MTDs are overall larger and correlate with the main uplift stages of the GB structure. Their distribution and relative timing suggest that failure-triggering earthquakes were common along the whole length of the GB. Pliocene to Quarternary MTDs tend to cluster along the northern half of the GB flank and are generally smaller. Based on our observations, we propose that the lifecycle of tectonic seamounts is marked by morphological rejuvenation episodes driven by tectonic activity between major collapse events or cycles. Tectonic-driven rejuvenation is thus key to hinder or obliterate evidence of past high-magnitude destructive events on tectonic seamount morphology.

21 pages.-- The data that support the findings of this study are available from Banca Dati Crop. Restrictions apply to the availability of these data, which were used under license for this study. Data are available at http://www.crop.cnr.it/ with the permission of the CROP DATABASE Project Manager, We present a new tectonic map focused upon the extensional style accompanying the formation of the Tyrrhenian back-arc basin. Our basin-wide analysis synthetizes the interpretation of vintage multichannel and single-channel seismic profiles, integrated with modern seismic images, P-wave velocity models, and high-resolution morpho-bathymetric data. Four distinct evolutionary phases of the Tyrrhenian back-arc basin opening are further constrained, redefining the initial opening to Langhian/Serravallian time. Listric and planar normal faults and their conjugates bound a series of horst and graben, half-graben and triangular basins. Distribution of extensional faults, active throughout the basin since Middle Miocene, allows us to define an arrangement of faults in the northern/central Tyrrhenian mainly related to a pure shear which evolved to a simple shear opening. At depth, faults accommodate over a Ductile-Brittle Transitional zone cut by a low-angle detachment fault. In the southern Tyrrhenian, normal, inverse and transcurrent faults appear to be related to a large shear zone located along the continental margin of the northern Sicily. Extensional style variation throughout the back-arc basin combined with wide-angle seismic velocity models allows to explore the relationships between shallow deformation, faults distribution throughout the basin, and crustal-scale processes as thinning and exhumation, With the funding support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI)

28 pages, 10 figures, 1 table, supporting information https://doi.org/10.1111/sed.12844.-- Data availability The data that support the findings of this study are available from the corresponding author upon reasonable request., Synchronous interaction between bottom currents and turbidity currents has been reported often in channel–levée systems where the thickness of the turbidity currents exceeds that of the levées. Such interplay between along-slope and down-slope sedimentary processes is one of the mechanisms by which ‘mixed turbidite–contourite systems’ can originate. However, bottom currents flow over large areas of the seafloor, including continental slopes characterized by deeply incised submarine canyons rather than channel levées. In these cases, a direct interaction between along-slope and down-slope currents is, theoretically, unlikely to take place. In this study, oceanographic, swath bathymetry, multichannel seismic data and sediment cores are used to investigate a 25 km long, 10 km wide and up to 0.5 km thick deep-sea late Quaternary deposit that sits adjacent to the north-west flank of one of the major canyons in the North Atlantic, the São Vicente Canyon, in the Alentejo Basin (south-west Iberian margin). The area receives the influence of a strong bottom current, the Mediterranean Outflow Water, which has swept the continental slope at different water depth ranges during glacial and interglacial periods. Architectural patterns and sediment characteristics suggest that this sedimentary body, named Marquês de Pombal Drift, is the result of the interaction between the Mediterranean Outflow Water (particularly during cold periods) and turbidity currents flowing along the São Vicente Canyon. Because the canyon is incised significantly deeper (ca 1.5 km) than the thickness of turbidity currents, an additional process, in comparison to earlier models, is needed to allow the interaction with the Mediterranean Outflow Water and transport sediment out of the canyon. In the São Vicente Canyon, and likely in other canyons worldwide, interaction of turbidity currents with contour currents requires intermediate nepheloid layers that export the finer-grained fraction of turbidity currents out of the canyon at the boundary between major water masses, This research received funding by the European Union’s Horizon 2020 research and innovating programme under the Marie Sklodowska-Curie grant via project ITN-SLATE (grant agreement No 721403). The Spanish “Ministerio de Ciencia e Innovación” and the European Regional Development Fund are also acknowledged for funding through grant CTM2015-70155-R (project INSIGHT), With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S)

16 pages, 11 figures, 1 table, supplementary data https://doi.org/10.1016/j.margeo.2020.106219, A multi-scale dataset consisting of multi-beam echo-sounder, 2D multi-channel seismic and sidescan sonar (TOBI) data allows us to identify a large variety of morphologies originating from sedimentary and tectonic processes along the São Vicente Canyon (SVC), which is the largest submarine canyon developed in the external part of the Gulf of Cadiz. The SVC is located in one of the most seismogenic areas of Western Europe. The convergence between the Eurasian and African plates has controlled the formation and evolution of the canyon. The SVC is tectonically controlled by three main thrust faults: the Marquês de Pombal Fault, the São Vicente Fault and the Horseshoe Fault. No major rivers feed sediment to the canyon head, but the main sediment source is related to the dismantling of canyon flanks and the MOW (Mediterranean Overflow Water). This current contributes sediments by two different processes: a) conturites deposition at the head and flanks of the SVC that periodically fail into the canyon; and b) the coarser-grained and denser sediment of the MOW might be trapped at the head of the canyon and could develops into hyperpycnal flows. The SVC is characterized by retrogressive erosion being submarine landslide deposits and scars the main seafloor morphologies. The tectonic and stratigraphic interpretation of seismic profiles indicate that the SVC is a clear example of a diachronous and segmented canyon developed since the Late Miocene in an area of present-day active plate tectonics. This study investigates the interaction between active tectonics, the dynamics of submarine canyons and the resulting geomorphologies, The authors are grateful for funding from MINECO through projects HITS (AC 2011), IMPULS (REN 2003-05996/MAR), ESF-EUROCORES “EuroMargins” (REN2002-11234-E MAR), SWIM (AE MCYT-DGI 2006), INSIGHT (CTM2015-70155-R), a MINECO FPI-2016 grant (ref. BES-2016-078877) to Cristina S. Serra (ICM-CSIC), and a MICINN “Juan de la Cierva-2017” grant (ref. 33838) to Sara Martínez-Loriente (ICM-CSIC)., With the funding support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI)

European Geosciences Union (EGU) General Assembly 2020, 4-8 May 2020, The Tyrrhenian Sea in the central Mediterranean Sea was form by Neogene slab roll-back of the retreating Ionian slab about 6 to 2 Myr ago. Yet, little is known about the structure of its southern margin off Sicily as well as back-arc extension and spreading in the southern Tyrrhenian Sea to the north of Sicily. The Sicilian margin is generally classified as a passive margin bounding a young back-arc basin. However, focal mechanisms from regional earthquakes suggest that the margins suffers presently from compressional tectonics. New seismic refraction and wide-angle data were collected along seismic profile WAS4 during the CHIANTI survey of the Spanish research vessel Sarmiento de Gamboa in 2015. The profile runs from the centre of the Tyrrhenian Sea - the Vavilov Basin - across the margin of Sicily, approaching the Gulf of Castellammare to the northwest of Sicily. Reanalyzed multi-channel seismic data supports compressional tectonics across a small basin paralleling the coastline of Sicily, revealing recent inversion of the Tyrrhenian Basin. Offshore of Sicily WAS4 indicates a roughly 120-140 km wide domain showing seismic P-wave velocities characteristic for continental crust (Vp ~4-6.7 km/s) and a base of crust defined by a wide-angle Moho reflection. Continental crust reaches a maximum thickness of 22 km to the north of the Gulf of Castellammare and is thinning to ~9 km to the north of the Ustica Ridge. The compressional belt occurs in continental crust to the south of Ustica Ridge. In the Vavilov Basin, a lithosphere was sample where seismic P-wave velocity increases from approx. 3-4 km/s to 7.5 km/s. This velocity depth-distribution clearly shows profound similarities to serpentinized mantle and hence un-roofed mantle. Thus, seismic constrains support results from Ocean Drilling Program (ODP) hole 651A, which sample serpentinized peridotites in the Vavilov Basin. The transition between serpentinized mantle and continental crust is rather abrupt. Thus, within a ~10 km wide transitional domain, continental crust with a thickness of~ 9 km is juxtaposed against un-roofed mantle. All available data from the Tyrrhenian Sea support wide-spread mantle exhumation in the Vavilov Basin. Therefore, the Tyrrhenian Sea provides a rather different structure when compared to marginal basins in the Western Pacific and hence may not have supported a mid-ocean ridge-type spreading system opening the basin

11 pages, 7 figures, supplementary material https://doi.org/10.1016/j.epsl.2020.116480, The formation of Cenozoic mountain belts in the Mediterranean realm was preceded by tens of millions of years of subduction, forming volcanic arcs, and frontal contractional systems. In addition, subduction usually involves slab rollback and formation of oceanic backarcs. Although such structure must have influenced the orogeny of Mediterranean mountain belts, no active analog has been mapped with modern crustal-scale seismic methods. Here, we study the entire Calabrian subduction system to map the structure resulting from Tethys lithosphere subduction and slab rollback, in a process that must be akin to that operating during a phase of the formation of the Mediterranean orogenic belts. We present a crustal-scale cross section of the entire Calabrian subduction system obtained from on- and off-shore wide-angle seismic data. The 2D P-wave velocity section shows spatially abrupt (, The CHIANTI survey was part of the HADES project funded by the Spanish MINECO (Ref # CTM2011-30400-C01 and CTM2011-30400-C02). [...] M. Prada is funded by the Beatriu de Pinós postdoctoral programme of the Government of Catalonia's Secretariat for Universities and Research of the Ministry of Economy and Knowledge (Ref # 2017BP00170), With the funding support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI)

European Geosciences Union (EGU) General Assembly 2020, 4-8 May 2020, The region at the transition from the west to the east Mediterranean is a complex puzzle of terrains spanning in age from the Mesozoic Ionian lithosphere to the Pleistocene arc and back arc domains of the Tyrrhenian system. Although the region has had a complicated evolutionary history, the current configuration of terrains fundamentally denotes Miocene to recent kinematics. In this contribution we present new data from Tunisia Margin showing the evolution from its formation in early Miocene to recent, the tectonic interaction with the opening of the Tyrrhenian system and its current inversion, and discuss the implications for the regional kinematics evolution. The Tyrrhenian is no longer extending, but all basin borders indicate currently active large-scale thrusting to strike slip tectonics. Tunisia margins formed by a well-know contractional tectonic phase in early Miocene expressed in large-scale tectonics with a clearly imaged thrust and fold belt, cut by Messinian to Pliocene extensional faulting. However, high resolution multibeam bathymetry and images of the shallowest layers indicates ongoing inversion tectonics. We compare the tectonic evolution of north Tunisia and Tyrrhenian with the patterns of deformation of the Ionian tectonic wedge observed in new and reprocessed seismic images. We interpret the current deformation of the Ionian tectonic wedge based on the integration of evolution of the kinematics from the data sets of observations from the three systems. We conclude that the entire region is currently under collision of the Africa Plate with the Adria Plate and the Neogene terrains of the Tyrrhenian Domain. The corollary is the subduction of the Ionian lithosphere is fundamentally stalled so that the megathrust fault is possibly not any longer accumulating significant shortening and most deformation is currently occurring in steeper faults re-activation or cutting the previous structural framework

21 pages, 11 figures, 2 appendices, supporting information https://dx.doi.org/10.1002/2017JC01272, data are available https://doi.org/10.1594/PANGAEA.875602

19 pages, 7 figures, The Alpine orogeny is well recorded onshore and offshore by tectonic inversion of the Mesozoic rift basins. Large scale linear seamounts (more than 250 km long and with up to 5 km of uplift) involving oceanic and continental lithosphere were carried on top of thrusts, such as the Gorringe seamount and the Estremadura Spur in the SouthWest and West Iberia Margin, respectively. The SouthWest Iberia Margin also recorded the westward migration of the Gibraltar Oceanic slab as the westwards propagation of the Neo-Tethys subduction. Rotation of the tectonic compression from NW-SE to WNW-ESE in Pliocene times caused the development of large scale dextral wrench faults as the present day Africa-Iberia plate boundary. Neotectonics of this plate boundary caused large to mega-scale destructive earthquakes and tsunamis

Seamounts are spectacular bathymetric features common within volcanic and tectonically active continental margins. During their lifecycles, they evolve through stages of construction and destruction. The latter are marked by variable magnitude flank collapses that often interrupt the evolution of seamounts and constitute a major source of hazard. The Southwest Iberian Margin is a tectonically complex region with moderate to high seismicity where numerous seamounts occur. On such a setting, earthquake-triggered collapses on seamount flanks are common, leading to the deposition of Mass-Transport Deposits (MTDs) on the surrounding abyssal plains. Using a wealth of 2D seismic reflection profiles, we investigate the lifecycle of the tectonic Gorringe Bank (GB), the largest submarine seamount offshore European margins, based on the magnitude and recurrence patterns of MTDs along the active thrust flank. Eight MTDs with relevant expression on the seismic data were analysed, four of estimated Miocene age and four on a Pliocene-Quaternary interval. Miocene MTDs are overall larger and correlate with the main uplift stages of the GB structure. Their distribution and relative timing suggest that failure-triggering earthquakes were common along the whole length of the GB. Pliocene to Quaternary MTDs tend to cluster along the northern half of the GB flank and are generally smaller. Overall, the size and magnitude of the mass-waste events is directly relatable to the magnitude of the uplift stages. Given the lack of indicators of large MTDs on the modern GB morphology, we propose that the lifecycle of tectonic seamounts is marked by morphological rejuvenation driven by thrust fault activity in between major collapse events or cycles. Tectonic-driven rejuvenation is thus key to hinder or obliterate evidence of past high-magnitude destructive events on tectonic seamount morphology.

Submarine mass failures represent one of the most significant marine geo-hazards. Their importance as a major contributor to tsunami generation and hazard has been recognized over the last 20–30 years. This study investigates a newly mapped submarine landslide, the South Hirondelle Landslide (SHL), and its potential to generate a tsunami and to threat the surrounding coasts. The SHL is located 150 km offshore South West Iberia, along the southern flank of the Hirondelle Seamount. Here, available swath bathymetry and one multichannel seismic profile show the presence of large, geometrically well constrained, deep-water landslide deposit of about 500 km 3 and its associated scar. The failure likely occurred in one single event and according to a detailed numerical modelling of the landslide dynamics and of the resulting water propagation the mass failure generated a mega-tsunami, with significant impact along the surrounding coastal areas of Iberia and Morocco. This result strongly supports the inclusion of tsunami induced by deep-water submarine landslides in the marine geo-hazard assessment of the North East Atlantic region.

19 pages, 10 figures, 2 tables, supporting information https://doi.org/10.1111/bre.12225, High‐resolution acoustic and seismic data acquired 100 km offshore Cape São Vicente, image with unprecedented detail one of the largest active reverse faults of the SW Iberian Margin, the Horseshoe Fault (HF). The HF region is an area seismogenically active, source of the largest magnitude instrumental and historical earthquake (Mw > 6) occurred in the SW Iberian Margin. The HF corresponds to a N40 trending, 110 km long, and NW‐verging active thrust that affects the whole sedimentary sequence and reaches up to the seafloor, generating a relief of more than 1 km. The along‐strike structural variability as well as fault trend suggests that the HF is composed by three main sub‐segments: North (N25), Central (N50) and South (N45). Swath‐bathymetry, TOBI sidescan sonar backscatter and parametric echosounder TOPAS profiles reveal the surface morphology of the HF block, characterized by several, steep (20°) small scarps located on the hangingwall, and a succession of mass transport deposits (i.e. turbidites) on its footwall, located in the Horseshoe Abyssal Plain. A succession of pre‐stack depth‐migrated multichannel seismic reflection profiles across the HF and neighbouring areas allowed us to constrain their seismo‐stratigraphy, structural geometry, tectono‐sedimentary evolution from Upper Jurassic to present‐day, and to calculate their fault parameters. Finally, on the basis of segment length, surface fault area and seismogenic depth we evaluated the seismic potential of the HF, which in the worst‐case scenario may generate an earthquake of magnitude Mw 7.8 ± 0.1. Thus, considering the tectonic behaviour and near‐shore location, the HF should be recognized in seismic and tsunami hazard assessment models of Western Europe and North Africa, The authors acknowledge the support of the Spanish Ministry of Science and Innovation (MICINN) through Acción Especial HITS (REN2000‐2150‐E) and National Projects EVENT (CGL2006‐12861‐C02‐02), SHAKE (CGL2011‐30005‐C02‐02), and INSIGHT (CTM2015‐70155‐R); the European Access of Seafloor Survey Systems EASSS‐III programme of the EC (HPRI‐CT99‐0047), the European Transnational Access SALVADORE program of the EU (RITA‐CT‐2004‐505322), the ESF EuroMargins SWIM project (01‐LEG‐EMA09F and REN2002‐11234E‐MAR), the EU program “Global Change and Ecosystems” contract n. 037110 (NEAREST), and the RSS “James Cook” Cruise JC027 of the National Oceanography Centre (Southampton, UK). We also acknowledge funding from the MICINN through the “Ramon y Cajal” program (R. Bartolome). [...] This work was carried out within the Grups de Recerca de la Generalitat de Catalunya B‐CSI (2014 SGR 940)

16 pages, 10 figures, supporting information http://gji.oxfordjournals.org/content/203/1/63/suppl/DC1, Geophysical data from the MEDOC experiment across the Northern Tyrrhenian backarc basin has mapped a failed rift during backarc extension of cratonic Variscan lithosphere. In contrast, data across the Central Tyrrhenian have revealed the presence of magmatic accretion followed by mantle exhumation after continental breakup. Here we analyse the MEDOC transect E-F, which extends from Sardinia to the Campania margin at 40.5°N, to define the distribution of geological domains in the transition from the complex Central Tyrrhenian to the extended continental crust of the Northern Tyrrhenian. The crust and uppermost mantle structure along this ~400-km-long transect have been investigated based on wide-angle seismic data, gravity modelling and multichannel seismic reflection imaging. The P-wave tomographic model together with a P-wave-velocity-derived density model and the multichannel seismic images reveal seven different domains along this transect, in contrast to the simpler structure to the south and north. The stretched continental crust under Sardinia margin abuts the magmatic crust of Cornaglia Terrace, where accretion likely occurred during backarc extension. Eastwards, around Secchi seamount, a second segment of thinned continental crust (7-8 km) is observed. Two short segments of magmatically modified continental crust are separated by the ~5-km-wide segment of the Vavilov basin possibly made of exhumed mantle rocks. The eastern segment of the 40.5°N transect E-F is characterized by continental crust extending from mainland Italy towards the Campania margin. Ground truthing and prior geophysical information obtained north and south of transect E-F was integrated in this study to map the spatial distribution of basement domains in the Central Tyrrhenian basin. The northward transition of crustal domains depicts a complex 3-D structure represented by abrupt spatial changes of magmatic and non-magmatic crustal domains. These observations imply rapid variations of magmatic activity difficult to reconcile with current models of extension of continental lithosphere essentially 2-D over long distances. © The Authors 2015. Published by Oxford University Press on behalf of The Royal Astronomical Society, We thank the teams involved in the MEDOC project and the Complementary Action OSMART, which has been funded by the Spanish Ministry of Science and Education, with reference CTM2007-66179-C02-01/MAR and CTM2007-66179-C02-02/MAR, and CTM2009-07772-E/MAR, respectively. This work was also supported by project CO-DOS funded by Repsol, the Grup de Recerca de la Generalitat de Catalunya (2014SGR940), and the German Science Foundation (DFG grant GR1964/14-1). [...] Works of MP and MGV have been funded by the Spanish CSIC’s Jae-PreDoc fellowship and the Spanish FPI grant system, respectively

In this work we investigate the crustal and tectonic structures of the Central Tyrrhenian back-arc basin combining refraction and wide-angle reflection seismic (WAS), gravity, and multichannel seismic (MCS) reflection data, acquired during the MEDOC (MEDiterraneo OCcidental)-2010 survey along a transect crossing the entire basin from Sardinia to Campania at 40°N. The results presented include a ~450 km long 2-D P wave velocity model, obtained by the traveltime inversion of the WAS data, a coincident density model, and a MCS poststack time-migrated profile. We interpret three basement domains with different petrological affinity along the transect based on the comparison of velocity and velocity-derived density models with existing compilations for continental crust, oceanic crust, and exhumed mantle. The first domain includes the continental crust of Sardinia and the conjugate Campania margin. In the Sardinia margin, extension has thinned the crust from ~20 km under the coastline to ~13 km ~60 km seaward. Similarly, the Campania margin is also affected by strong extensional deformation. The second domain, under the Cornaglia Terrace and its conjugate Campania Terrace, appears to be oceanic in nature. However, it shows differences with respect to the reference Atlantic oceanic crust and agrees with that generated in back-arc oceanic settings. The velocities-depth relationships and lack of Moho reflections in seismic records of the third domain (i.e., the Magnaghi and Vavilov basins) support a basement fundamentally made of mantle rocks. The large seamounts of the third domain (e.g., Vavilov) are underlain by 10–20 km wide, relatively low-velocity anomalies interpreted as magmatic bodies locally intruding the mantle.

We present a new classification of geological domains at the Africa-Eurasia plate boundary off SW Iberia, together with a regional geodynamic reconstruction spanning from the Mesozoic extension to the Neogene-to-present-day convergence. It is based on seismic velocity and density models along a new transect running from the Horseshoe to the Seine abyssal plains, which is combined with previously available geophysical models from the region. The basement velocity structure at the Seine Abyssal Plain indicates the presence of a highly heterogeneous, thin oceanic crust with local high-velocity anomalies possibly representing zones related to the presence of ultramafic rocks. The integration of this model with previous ones reveals the presence of three oceanic domains offshore SW Iberia: (1) the Seine Abyssal Plain domain, generated during the first stages of slow seafloor spreading in the NE Central Atlantic (Early Jurassic); (2) the Gulf of Cadiz domain, made of oceanic crust generated in the Alpine-Tethys spreading system between Iberia and Africa, which was coeval with the formation of the Seine Abyssal Plain domain and lasted up to the North Atlantic continental breakup (Late Jurassic); and (3) the Gorringe Bank domain, made of exhumed mantle rocks, which formed during the first stages of North Atlantic opening. Our models suggest that the Seine Abyssal Plain and Gulf of Cadiz domains are separated by the Lineament South strike-slip fault, whereas the Gulf of Cadiz and Gorringe Bank domains appear to be limited by a deep thrust fault located at the center of the Horseshoe Abyssal Plain.

Extension of the continental lithosphere leads to the formation of rift basins and ultimately may create passive continental margins. The mechanisms that operate during the early stage of crustal extension are still intensely debated. We present the results from coincident multichannel seismic and wide-angle seismic profiles that transect across the northern Tyrrhenian Sea Basin. The profiles cross the Corsica Basin (France) to the Latium Margin (Italy) where the early-rift stage of the basin is well preserved. We found two domains, each with a distinct tectonic style, heat flow and crustal thickness. One domain is the Corsica Basin in the west that formed before the main rift phase of the northern Tyrrhenian Sea opening (∼8–4 Ma). The second domain is rifted continental crust characterized by tilted blocks and half-graben structures in the central region and at the Latium Margin. These two domains are separated by a deep (∼10 km) sedimentary complex of the eastern portion of the Corsica Basin. Travel-time tomography of wide-angle seismic data reveals the crustal architecture and a subhorizontal 15–17 ± 1 km deep Moho discontinuity under the basin. To estimate the amount of horizontal extension we have identified the pre-, syn-, and post-tectonic sedimentary units and calculated the relative displacement of faults. We found that major faults initiated at angles of 45°–50° and that the rifted domain is horizontally stretched by a factor of β ∼ 1.3 (∼8–10 mm/a). The crust has been thinned from ∼24 to ∼17 km indicating a similar amount of extension (∼30%). The transect represents one of the best imaged early rifts and implies that the formation of crustal-scale detachments, or long-lived low-angle normal faults, is not a general feature that controls the rift initiation of continental crust. Other young rift basins, like the Gulf of Corinth, the Suez Rift or Lake Baikal, display features resembling the northern Tyrrhenian Basin, suggesting that half-graben formations and distributed homogeneous crustal thinning are a common feature during rift initiation.

Special issue Deep Seismix.-- 10 pages, 7 figures, supplementary data https://doi.org/10.1016/j.tecto.2016.01.041, The Tyrrhenian basin opened in the Neogene following the E–SE retreat of the Appenines–Calabrian subduction system and the subsequent back-arc extension of an orogenic crust. The resultant crustal structure includes a complex distribution of continental, back-arc magmatism, and mantle-exhumation domains. A clear example of this complex structure is found in the central and deepest part of the basin (i.e. Magnaghi–Vavilov sub-basin) where geophysical data supported that the bulk of the basement is composed of partially serpentinised peridotite representing exhumed mantle rocks, and intruded by basalts forming low ridges and volcanic edifices. However, those data sets cannot univocally demonstrate the widespread presence of serpentinised mantle rocks, let alone the percentage of serpentinisation. Here, we use S-wave arrivals and available geological information to further constrain the presence of mantle serpentinisation. Travel times of converted S-waves were used to derive the overall Vp/Vs and Poisson's ratio (σ), as well as S-wave velocity of the basement in the Magnaghi-Vavilov Basins. This analysis reveals Vp/Vs ≈ 1.9 (σ ≈ 0.3) that strongly supports a serpentinised peridotite forming the basement under the basins, rather than oceanic-type gabbro/diabase. P-wave velocity models is later used to quantify the amount of serpentinisation from fully serpentinised (up to 100%) at the top of the basement to < 10% at 5-7 km deep, with a depth distribution similar to continent–ocean Transition zones at magma-poor rifted margins. Seismic reflection profiles show normal faulting at either flank of the Magnaghi–Vavilov Basin that is potentially responsible for the onset of serpentinisation and later mantle exhumation. These results, together with basement sampling information in the area, suggests that the late stage of mantle exhumation was accompanied or soon followed by the emplacement of MOR-type basalts forming low ridges that preceded intraplate volcanism responsible for the formation of large volcanoes in the area, We thank the teams involved in the MEDOC project and the Complementary Action OSMART, which has been funded by the Spanish Ministry of Science and Education, with reference CTM2007-66179-C02-01/MAR, CTM2007-66179-C02-02/MAR, and CTM2009-07772-E/MAR, respectively. This work was also supported by project CO-DOS funded by Repsol, the Grup de Recerca de la Generalitat de Catalunya: Barcelona Center for Subsurface Imaging (2014SGR940), and the German Science Foundation (DFG grant GR1964/14-1)

The contourite drifts off southwest Iberia that formed as a result of the interaction of the Mediterranean Outflow Water (MOW) with the continental middle slope were studied in the Algarve margin using multichannel reflection seismic lines, oil-wells, piston cores, and a bathymetric compilation of four datasets. The seismostratigraphic interpretation of a dense array of oil industry seismic and stratigraphic correlation allowed the identification of five seismic units of Early Pliocene through Holocene in the Faro and Albufeira drifts and four correlative seismic units in the Lagos and Sagres drifts and three in the Portimao drift. A three-phased evolutionary model for the contourite formation is proposed. Firstly, a precursory phase of Pliocene age made up of sheeted drifts represents an initial phase of deposition under bottom-current activity that is correlated with the first stages of an enhanced MOW at about 3.5 Ma. Secondly, the building up phase of Early Pleistocene age is related to a strengthening of the MOW close to the onset of the Northern Hemisphere glaciations at about 2.6 Ma during which were deposited low-mounded drifts. Thirdly, the growing phase from Middle-Pleistocene through Holocene suggests the presence of a stronger MOW since the beginning of the Middle-Pleistocene Transition at about 1.3–1.0 Ma, accounting for the deposition of mounded drifts and formation of the Alvares Cabral moat. Seismostratigraphic interpretation and isochron maps allowed for the establishment of the main oceanographic, climatic, morphologic and tectonic factors that controlled the drifts deposition: i) the Pliocene and Quaternary MOW circulation forced by climate changes; ii) the sea bottom topography inherited from the Late Miocene, mainly shaped by the Portimao, Lagos and Bartolomeu Dias canyons system; iii) the interaction between along-slope and down-slope processes since the Pliocene; and iv) Pliocene–Quaternary fault-activity and diapirism.

It It is well documented that, in the past, catastrophic earthquakes and tsunamis affected the area as described in the historical records from the countries bordering the Gulf of Cadiz: Portugal, Spain and Morocco (cf. Baptista and Miranda, 2009; Figure 6.1). The main mechanism behind geohazard generation in this area is the interplate deformation arising from the relative motion between the Eurasian and Nubian (African) plates. The plate boundary crosses the Gulf of Cadiz but the precise location of its trace is not yet well understood. In the Gulf of Cadiz the morphology is complex and characterized by a series of large ridges and seamounts, the Gorringe Bank, the Coral Patch and Ampère seamounts (cf. Figure 6.1 for locations), bounding major morphological depressions such as the Horseshoe and Tagus abyssal plains and discrete segments of plate boundary are hard to identify due to diffuse deformation over an area 200km wide (Sartori et al., 1994; Tortella et al., 1997). © Springer-Verlag Berlin Heidelberg

The work published recently by Vilanova et al. (2003) in the Bulletin of the Seismological Society of America proposes that the accounts of destruction and other effects reported in the Lisbon area as a result of the 1 November 1755 earthquake are best explained by a local rupture on the Lower Tagus Valley fault (ltvf), triggered by the static stress change produced by the main offshore source located in the Gorringe area. Because of the potential impact of this hypothesis on the seismic hazard of the Lisbon area, we discuss and complement the evidence presented by Vilanova and co-workers, concluding that the “local rupture model” should remain, for the moment, as an unsubstantiated speculation. Vilanova et al. (2003) (referred to herein as “the authors” or “the paper”) compare the intensities reported for the 1755 earthquake in Lisbon and Algarve to conclude that Lisbon intensities are abnormally high for the same distance, in particular, when compared with what was observed for the 28 February 1969 earthquake. They interpreted this as the result of local rupture. In Figure 1 we re-plot the macroseismic intensity as a function of the distance to the Gorringe Bank source presumed by the authors. We can see that “Lower Tagus Valley intensities” do not show any abnormal behavior. Similar plots could be made for all source areas proposed by other authors (Baptista, 1998; Baptista et al. , 1998a, 1998b; Zitellini et al. , 1999, 2001; Terrinha et al. , 2003) with minor changes to the conclusion we reached previously. The conclusions reached by the authors were based on their figure 8A, from which intensity values for the Algarve and Portuguese west coast corresponding to distances greater than 350 km are missing. Figure 1. Modified Mercalli (MM) intensities for the 1755 earthquake, plotted as a …

Over the last two decades numerous studies have investigated the structure of the west Iberia continental margin, a non-volcanic margin characterized by a broad continent–ocean transition (COT). However, the nature and structure of the crust of the segment of the margin off SW Iberia is still poorly understood, because of sparse geophysical and geological data coverage. Here we present a 275-km-long multichannel seismic reflection (MCS) profile, line AR01, acquired in E–W direction across the Horseshoe Abyssal Plain, to partially fill the gap of information along the SW Iberia margin. Line AR01 runs across the inferred plate boundary between the Iberian and the African plates during the opening of the Central Atlantic ocean. The boundary separates crust formed during or soon after continental rifting of the SW Iberian margin from normal seafloor spreading oceanic crust of the Central Atlantic ocean. Line AR01 has been processed and pre-stack depth migrated to show the tectonic structure of the crust across the palaeo plate boundary. This boundary is characterized by a 30–40-km-wide zone of large basements highs related to landward-dipping reflections, which penetrate to depths of 13–15 km, and it marks a change in the character of the basement structure and relief from east to west. In this study, we have used pre-stack depth migrated images, the velocity model of line AR01 and magnetic data available in the area to show that the change in basement structure occurs across the fossil plate boundary, separating African oceanic crust of the M series (M21–M16) to the west from the transitional crust of the Iberian margin to the east.

The Tyrrhenian Sea is a Neogene back-arc basin formed by continental extension at the rear of the eastward migrating Apennine subduction system. Its central part, generated from Tortonian to Pliocene, includes the Sardinia rifted margin to the west, an area with large volcanoes in the deep central sector, and the Campania rifted margin to the east. A reprocessing of some 2000 km of MCS lines, a new swath bathymetric map, and a review of previous geological and geophysical data allow to analyse the nature and distribution of continental vs. oceanic crust in this area, which evolved in a short time span. The central portion of the southern Tyrrhenian Sea is characterized by MOHO at about 10 km depth. North of Magnghi and Vavilov Smts, this thinned crustal domain include a wide continent–ocean transition, with the occurrence of extensional allochthons and of serpenitinzed sub-continental mantle, recalling other well known rifted margins, as the Iberia one. Sectors floored by oceanic crust should occur, mainly in the southern part of the study area, but they do not appear related to discrete spreading ridges. The continent–ocean boundary cannot be drawn unequivocally in the area, due also to the occurrence of widespread and huge magmatic manifestations not related to oceanic spreading. These portions of the southern Tyrrhenian Sea represents therefore a complex oceanic back-arc basin surrounded by magma-rich rifted continental margins. The abundant igneous manifestations and the very high stretching rates observed in the area may be related to the fact that the present Tyrrhenian area was occupied by an orogenic domain affected by shortening until middle Miocene times, which is just before the Late Miocene onset of back-arc extension. The lithosphere in the region had then to be rheologically weak. Abundant generation and ascent of magmas, mostly of Ocean Island Basalt type, was favoured by the large lithospheric permeability induced by strong extensional deformations.

23 pages, 13 figures, Extension of the continental lithosphere leads to the formation of rift basins or rifted continental margins if breakup occurs. Seismic investigations have repeatedly shown that conjugate margins have asymmetric tectonic structures and different amount of extension and crustal thinning. Here we compare two coincident wide-angle and multichannel seismic profiles across the northern Tyrrhenian rift system sampling crust that underwent different stages of extension from north to south and from the flanks to the basin center. Tomographic inversion reveals that the crust has thinned homogeneously from similar to 24 km to similar to 17 km between the Corsica Margin and the Latium Margin implying a beta factor of similar to 1.3-1.5. On the transect 80 km to the south, the crust thinned from similar to 24 km beneath Sardinia to a maximum of similar to 11 km in the eastern region near the Campania Margin (beta factor of similar to 2.2). The increased crustal thinning is accompanied by a zone of reduced velocities in the upper crust that expands progressively toward the southeast. We interpret that the velocity reduction is related to rock fracturing caused by a higher degree of brittle faulting, as observed on multichannel seismic images. Locally, basalt flows are imaged intruding sediment in this zone, and heat flow values locally exceed 100 mW/m(2). Velocities within the entire crust range 4.0-6.7 km/s, which are typical for continental rocks and indicate that significant rift-related magmatic underplating may not be present. The characteristics of the pre-tectonic, syn-tectonic and post-tectonic sedimentary units allow us to infer the spatial and temporal evolution of active rifting. In the western part of the southern transect, thick postrift sediments were deposited in half grabens that are bounded by large fault blocks. Fault spacing and block size diminish to the east as crustal thinning increases. Recent tectonic activity is expressed by faults cutting the seafloor in the east, near the mainland of Italy. The two transects show the evolution from the less extended rift in the north with a fairly symmetric conjugate structure to the asymmetric margins farther south. This structural evolution is consistent with W-E rift propagation and southward increasing extension rates., This work was funded by the Deutsche Forschungsgemeinschaft (DFG) under grant GR 1964 /14-1 and the complementary Action OSMART, which has been funded by the Spanish Ministry of Science and Education, with reference CTM2007-66179-C02-01/MAR and CTM2007-66179-C02-02/MAR, and CTM2009-07772-E/MAR, respectively

On November 1, 1755, the city of Lisbon was completely devastated by the combined effect of a tremendous earthquake, tsunami waves, and fire. The 1755 Lisbon earthquake was the most destructive cataclysm recorded in western Europe since the Roman Republic, with an estimated earthquake magnitude Mw ∼8.5 [Martins and Mendes Victor, 1990] and estimated tsunami magnitude of Mt= Mw= 8.5. The earthquake was felt as far away as Great Britain and Finland. The tsunami hit many coastal cities along southwest Iberia and North Africa, causing heavy destruction in Tanger and Casablanca.

The reprocessing of MCS reflection lines and sampling data across the SW Tyrrhenian Basin, from the Sardinia–Tunisia Strait (STS) to the Orosei Canyon Line (OCL), show that the acoustic basement of the area is made by Variscan crystalline-metamorphic rocks covered by a thick sequence of sediments, including the Messinian interval. The pre-Messinian sequence can be subdivided into three seismic intervals or subunits, largely calibrated by sampling data. The oldest pre-Messinian subunit is strongly deformed by compressional and/or transpressional structures and the recovered samples are deep-water arkosic sediments, Aquitanian in age; however, the whole interval may encompass a wider time span, probably from Late Oligocene to Langhian. This subunit was laid down in a fore-arc basin located between a volcanic arc (Sardinia) and an accretionary wedge (Calabrian–Peloritanian–Kabilide or CK units) prior to the collision of the latter elements with the continental margin of Africa in Sicily and Tunisia along the so-called Drepano Thrust Front (DTF). Coeval to collision, the generation of the Main Sardinia Thrust (MST) occurred, carrying the Sardinia basement rocks over the CK units, and deforming the fore-arc basin sediments. The intermediate pre-Messinian sedimentary subunit spans from part of Serravallian to part of Tortonian. It is post-tectonic with respect to the underlying subunit, but it represents a pre-rift succession, if related to the overlying one. It consists of terrigenous deposits prograding from Sardinia to the ENE into a basin some hundreds of meters deep, which was left in the area after collision. The youngest pre-evaporitic subunit (late Tortonian–early Messinian in age) displays wedge-shaped reflectors in the Sardinia Basin, and forms the lower portion of a syn-rift complex including the Messinian and part of the Pliocene sediments. This succession records the onset of extensional tectonics in the area, as also testified by the Tortonian age of exumation of the basement. While in the Tyrrhenian Basin, north of the OCL, intra-Tortonian to intra-Pliocene rifting was strong but discontinuous and migrating with time to the east, in the SW Tyrrhenian Basin, in contrast, rifting was less severe but continuous during the same time interval. This emphasizes the role played by the OCL, a inherited Mesozoic discontinuity reactivated as a transfer zone during the Neogene. These new data allow correlation of the main Miocene deformational events observed in the study area to those of the adjacent emerged areas, namely the Peloritani and Maghrebian units in Sicily, prior to the Pliocene–Quaternary full development of the southern Tyrrhenian Sea.

The oceanic crust of the northern Weddell Sea and Scotia Sea contains the following principal morphostructural elements: (1) the South Scotia Ridge and the South Orkney Microcontinent, both with continental crust; (2) the oceanic Powell and Jane basins; and (3) Jane Bank, which belongs to an island arc. The analysis of MCS profiles and of gravimetric and magnetic data from Russian, Italian and Spanish cruises, supplemented with satellite gravimetric data, has enabled us to determine the relationship between these elements and to propose a model for the main stages of Cenozoic evolution in the area. During the early Cenozoic, the Weddell Sea oceanic crust was subducted under the southern margin of the South Orkney Microcontinent. The subduction probably ended westwards at the South Powell Ridge, a submarine extension of the Antarctic Peninsula. A major transcurrent fault zone is identified in the northwestern Weddell Sea, bounding oceanic crust of Mesozoic and Cenozoic ages. This fault zone was probably active at least to the Miocene. The drifting of the South Orkney Microcontinent from the Antarctic Peninsula during the late Eocene to early Miocene originated the Powell Basin. Jane Basin developed as a backarc, related to the subduction of the Weddell Sea oceanic crust below Jane Bank. The seismic stratigraphy of the depositional sequences in these two basins indicates that spreading in Jane Basin started simultaneously with the end of the opening in Powell Basin. The active spreading ridge of the Weddell Sea collided with the trench and was subducted below Jane Bank at 15–20 Ma. Drifting in Jane Basin and subduction below Jane Bank ended shortly thereafter, in the middle Miocene, and the boundary between the Antarctic/Scotia plates migrated north of the South Orkney Microcontinent, along the South Scotia Ridge. Present tectonic activity in the region is minor.

The Powell Basin, located near the Scotia-Antarctica strike-slip plate boundary, is bounded on three sides by continental crustal blocks, and it separates the South Orkney microcontinent from the northeastern Antarctic Peninsula. On the basis of the entire geophysical data set available, the main structural and geological elements of the basin are identified. The northern domain is characterized by an oceanic-like environment, with a ridge axis in the centre of the basin. Two conjugate deep, restricted sedimentary basins are located at the base of the northeastern and northwestern margins, and filled by thick sedimentary sequences. The southern domain is mainly floored by transitional crust and presents rift-related basement graben. The margins surrounding the basin are different, with the northern and southern margins mainly transcurrent, whereas most of the eastern and western margins show passive margin characteristics. The sedimentary sequences filling the basin have been correlated to the main tectonic processes responsible for Powell Basin opening, and partially dated using marine magnetic anomaly identifications. Three main evolutionary phases are recognized that explain the geological setting of the Powell Basin. An early phase of separation between the Antarctic Peninsula and the South Orkney microcontinent produced stretching and progressive continental lithospheric thinning, with the creation of restricted pull-apart basins (proto-Powell phase). This phase was followed by a northward movement, possibly accomplished with a clockwise rotation, of the South Orkney microcontinent (drift phase), with consequent oceanic crustal accretion in the northern sector of the basin, and development of rift-related structures in the southern sector (phase spanning 27-18 Ma, as determined from the marine magnetic anomalies). A successive clockwise rotation of the South Orkney microcontinent determined the complete development of the northern sector of the basin, with spreading and final structuration of the margins encircling the basin plain.

The central-eastern Atlantic continental slope and parts of the Horseshoe and Seine Plains, west of the Gibraltar Arc, are occupied by a seismically chaotic body. This paper reports new deep seismic reflection data that allows a first assessment of the three-dimensional geometry of the body, and discussion of its evolution. The seismically chaotic body is huge in area and volume and complex in origin, comprising mainly gravity deposits (debris flows, olistostromes) in the northern sector, and tectonic melanges in the southern, where the body forms part of a south-verging accretionary prism related to Africa-Iberia convergence (submarine extension of the Rifian system of N-Africa). The northern part, up to several tens of thousands of cubic kilometers in volume, results from the superposition of a few endoolistostromes, probably of Miocene age, centripetally discharged onto the Eastern Horseshoe Plain and adjacent slope from structural highs generated during the Late Miocene paroxismal phase of Iberia-Africa convergence. Submarine flows were triggered along regional, continuous slopes up to 100 km in length. Their volume largely exceeds previously reported marine occurrences of gravity flow deposits, the outstanding examples of which occur in intraplate settings (hot spots, old passive margins). At the boundaries (lateral or frontal ramps) of the southern tectonic melange complex, smallscale olistostromes of Pliocene age also occur, recalling the so-called precursory olistostromes of collisional chains. The gravity and tectonic structures occur in a convergent plate setting, with low shortening rates, and their eventual fate will be incorporation, with disruption, in a collisional chain. Their volume and extent appear comparable to those that can be calculated for huge chaotic units in orogens, such as the ‘Argille scagliose' (=Liguride complex) of the Apennines, in which disrupted olistostromes and tectonic melanges coexist.

Martínez-Loriente, S. ... et al.-- 26 pages, 13 figures, 1 table, Recently acquired high-resolution multichannel seismic profiles together with bathymetric and sub-bottom profiler data from the external part of the Gulf of Cadiz (Iberia-Africa plate boundary) reveal active deformation involving old (Mesozoic) oceanic lithosphere. This area is located 180 km offshore the SW Iberian Peninsula and embraces the prominent NE-SW trending Coral Patch Ridge, and part of the surrounding deep Horseshoe and Seine abyssal plains. E-W trending dextral strike-slip faults showing surface deformation of flower-like structures predominate in the Horseshoe Abyssal Plain, whereas NE-SW trending compressive structures prevail in the Coral Patch Ridge and Seine Hills. Although the Coral Patch Ridge region is characterized by subdued seismic activity, the area is not free from seismic hazard. Most of the newly mapped faults correspond to active blind thrusts and strike-slip faults that are able to generate large magnitude earthquakes (Mw 7.2-8.4). This may represent a significant earthquake and tsunami hazard that has been overlooked so far. Key Points New active structures have been mapped in the Coral Patch Ridge area The newly mapped faults are able to generate large magnitude earthquakes (Mw>7) These new structures may represent a significant earthquake and tsunami hazard ©2013. American Geophysical Union. All Rights Reserved, The authors acknowledge the support of the Spanish Ministry of Science and Innovation (MICINN) through National Projects EVENT (CGL2006–12861-C02-02) and SHAKE (CGL2011–30005-C02-02); the European Transnational Access SALVADORE program of the EU (RITA-CT-2004–505322), the ESF EuroMargins SWIM project (01- LEG-EMA09F and REN2002–11234E-MAR), the EU program ‘‘Global Change and Ecosystems’’ contract n. 037110 (NEAREST), the ESF TopoEurope TOPOMED project (CGL2008–03474-E/BTE), and the SWIMGLO project (PTDC/MAR/100522/2008). We also acknowledge funding from the MICINN through the ‘‘Ramon y Cajal’’ program (R. Bartolome) and from the CSIC through a JAE Pre-Doc fellowship (S. Martínez-Loriente)

Geophysical and geological marine data recently collected allow to outline the structure of the basement-involved fold-thrust belt, developed during the Late Cenozoic between Sardinia and Tunisia, along the Africa-Europe plate boundary. By integrating these with inland data, it is possible to document, step by step, the progression of crustal thickening from north to south, and the collapse of the first uplifted northern units, while collision was still going on. The geodynamic setting suggests that coupled extensional collapse and fold-thrust propagation were driven by island arc drifting above a southward-retreating subduction zone.

12 pages, 9 figures, We investigate the crustal structure of the SW Iberian margin along a 340 km-long refraction and wide-angle reflection seismic profile crossing from the central Gulf of Cadiz to the Variscan continental margin in the Algarve, Southern Portugal. The seismic velocity and crustal geometry model obtained by joint refraction and reflection travel-time inversion reveal three distinct crustal domains: the 28–30 km-thick Variscan crust in the north, a 60 km-wide transition zone offshore, where the crust abruptly thins ~ 20 km, and finally a ~ 7 km-thick and ~ 150 km-wide crustal section that appears to be oceanic in nature. The oceanic crust is overlain by a 1–3 km-thick section of Mesozoic to Eocene sediments, with an additional 3–4 km of low-velocity, unconsolidated sediments on top belonging to the Miocene age, Gulf of Cadiz imbricated wedge. The sharp transition between continental and oceanic crust is best explained by an initial rifting setting as a transform margin during the Early Jurassic that followed the continental break-up in the Central Atlantic. The narrow oceanic basin would have formed during an oblique rifting and seafloor spreading episode between Iberia and Africa that started shortly thereafter (Bajocian) and lasted up to the initiation of oceanic spreading in the North Atlantic at the Tithonian (late Jurassic-earliest Cretaceous). The velocity model displays four wide, prominent, south-dipping low-velocity anomalies, which seem to be related with the presence of crustal-scale faults previously identified in the area, some of which could well be extensional faults generated during this rifting episode. We propose that this oceanic plate segment is the last remnant of an oceanic corridor that once connected the Alpine-Tethys with the Atlantic ocean, so it is, in turn, one of the oldest oceanic crustal fragments currently preserved on Earth. The presence of oceanic crust in the central Gulf of Cadiz is consistent with geodynamic models suggesting the existence of a narrow, westward retreating oceanic slab beneath the Gibraltar arc-Alboran basin system, The NEAREST project has been funded by the EU Programme “Integrating and Strengthening the European Research Area” of FP6, Sub-Priority 1.1.6.3, “Global Change and Ecosystems”, contract no. 037110, and the NEARESTSEIS survey was funded by the Complementary Action # CGL2006-27098-E/BTE of the Spanish MICINN. Additional funds were obtained from the MICINN projects MEDOC (CTM2007-66179-C02-02/MAR) and SHAKE (CGL2011-30005-C02-02). We also acknowledge funding from MICINN through the Ramon y Cajal program (R. Bartolomé). We finally acknowledge the collaboration of our research partners at Grup de Recerca de la Generalitat de Catalunya Barcelona Centre of Subsurface Imaging (B-CSI) ref. 2009 SGR 146 and funding support from Repsol-YPF

NEMO-SN1, located in the central Mediterranean Sea, Western Ionian Sea, off Eastern Sicily Island (Southern Italy) at 2100 m water depth, 25 km from the harbour of the city of Catania, is a prototype of a cabled deep-sea multiparameter observatory and the first operating with real-time data transmission in Europe since 2005. NEMO-SN1 is also the first-established node of EMSO (European Multidisciplinary Seafloor Observatory, http://emso-eu.org), one of the incoming European large-scale research infrastructure included since 2006 in the Roadmap of the ESFRI (European Strategy Forum on Research Infrastructures, http://cordis.europa.eu/esfri/roadmap.htm), which will specifically address long-term monitoring of environmental processes related to Marine Ecosystems, Climate Change and Geo-hazards. NEMO-SN1 has been deployed and developed over the last decade thanks to Italian resources and to the EC project ESONET-NoE (European Seas Observatory NETwork — Network of Excellence, 2007–2011) that funded the LIDO-DM (Listening to the Deep Ocean — Demonstration Mission) and a technological interoperability test (http://www.esonet-emso.org/esonet-noe/). NEMO-SN1 is performing geophysical and environmental long-term monitoring by acquiring seismological, geomagnetic, gravimetric, accelerometric, physico-oceanographic, hydro-acoustic, bio-acoustic measurements specifically related to earthquakes and tsunamis generation and ambient noise characterisation in term of marine mammal sounds, environmental and anthropogenic sources. A further main feature of NEMO-SN1 is to be an important test-site for the construction of KM3NeT (Kilometre-Cube Underwater Neutrino Telescope, http://www.km3net.org/), another large-scale research infrastructure included in the ESFRI Roadmap constituted by a large volume neutrino telescope. The description of the observatory and the most recent data acquired will be presented and framed in the general objectives of EMSO.

Terra Nova, 22, 494–500, 2010 Abstract New detailed swath bathymetry and bottom samples from Coral Patch and Ormonde seamounts provide constraints on the emplacement of the Madeira hotspot in the Eastern Atlantic Ocean. Swath bathymetric data document that Coral Patch is a composite structure, made up of at least nine distinct volcanic centres. Lithified pelagic carbonates infilling fissures in lava blocks constrain a minimal age for the volcanism in the Early Miocene and represent the first documentation of Coral Patch acting as an offshore terrigenous-starved seamount. At Coral Patch, as already observed at the Ormonde seamount, volcanism was emplaced on top of a pre-existing relief resulting from the regional tectonic compressive regime.

The present paper reviews the proposed sources for the 1/11/1755 Lisbon earthquake in the context of the geodynamics of Southwest Iberia, the region where it was generated. We will also refer briefly the implications for seismic hazard both at global and regional scale. Because the 1755 earthquake occurred before the foundation of instrumental seismology, the source location and mechanism can be inferred only on the basis of the Historical Seismicity through interpretation of records of direct witnesses of the earthquake and tsunami (Pereira de Sousa 1919–1932), through the geological record left by the tsunami in the SW coast of Portugal (Andrade 1992) and through the evidences of downslope mass movement triggered by the earthquake as recorded in the sedimentary column of the surrounding Abyssal Plains (Lebreiro et al. 1997). The isoseismal distribution derived by the description of the damages suggested a seismic moment magnitude of 8.7 and source area located SW of Lisbon (Richter 1958, Johnston 1996, Buforn et al. 1988, 2004). The West-Iberia continental margin is more active in terms of instrumental and historical seismicity than usual for passive Atlantic-type margins. Epicentres distribution shows that Iberia is characterized by an inner core with increased rigidity and stability with respect to its margins. Reconstruction of the present day stress field shows deviations of the maximum compressive stress trajectories from the core of Iberia, where they are oriented NNW-SSE, to its western margin, where they become WNW-ESE oriented (Ribeiro et al. 1996, Ribeiro 2002). Along theN-S trendingWest Iberia Margin the orientation of the main compression also changes from approximately NW-SE in the north toWNW-ESE in the south. It was firstly argued by Ribeiro and Cabral (1986, 1987) and Ribeiro et al. (1996) that the West Iberia Margin initiated the process of transition from passive margin to active margin

19 pages, 18 figures, 1 table, The Gulf of Cadiz, off SW Iberia and the NW Moroccan margin, straddles the cryptic plate boundary between Africa and Eurasia, a region where the orogenic Alpine compressive deformation in the continental collision zone passes laterally to the west to strike-slip deformation. A set of new multibeam bathymetry, multi-channel and single channel seismic data presented here image the main morphological features of tectonic origin of a significant part of the Gulf of Cadiz from the continental shelf to the abyssal plain. These morphotectonic features are shown to result from the reactivation of deeply rooted faults that changed their kinematics from the early Mesozoic rifting, through the Late Cretaceous-Paleogene collision, to Pliocene-Quaternary thrusting and wrenching. The old faults control deep incised, more than 100 km long canyons and valleys. Several effects of neotectonics on deep water seabed are shown. These include: i) the complex morphology caused by wrenching on the 230 km long WNW-ESE faults that produced en echelon folds on the sediments; ii) the formation of up to 5 km wide crescent shaped scours at roughly 4 km water depth by reactivation of thrusts; iii) 10 km long creep folds on the continental slope; and iv) the formation of landslides on active fault escarpments. The present day deformation is partitioned on NE-SW thrusts and WNW-ESE to W-E strike-slip faults and is propagating northwards on N-S trending thrusts along the West Iberia Margin from 35.5°N to 38°N, which should be considered for seismic hazard, The work was sponsored by MATESPRO (PDCTM/P/MAR/15264/1999), EUROMARGINS SWIM (01-LEC-EMA09F), MVSEIS (01-LEC_EMA24F; PDCTM 72003/DIV/40018) and TOPOMED (TOPOEUROPE/0001/2007) projects. Instituto Scienze Marine (CNR) Bologna contribution 1587. JD and VV benefited from PhD grants from Fundação para a Ciência e a Tecnologia (SFRH/BD/31188/2006, SFRH/BD/17603/2004). We acknowledge the PARSIFAL Project MAR1998-1837-CE for the use of bathymetry data. We acknowledge the financial support from the ESF EuroMargins Program, contract n. 01-LEC-EMA09F and from EU Specific Programme "Integrating and Strengthening the European Research Area", Sub-Priority 1.1.6.3, "Global Change and Ecosystems", contract n. 037110 (NEAREST)

A new swath bathymetry compilation of the Gulf of Cadiz Area and SW Iberia is presented. The new map is the result of a collaborative research performed after year 2000 by teams from 7 European countries and 14 research institutions. This new dataset allow for the first time to present and to discuss the missing link in the plate boundary between Eurasia and Africa in the Central Atlantic. A set of almost linear and sub parallel dextral strike-slip faults, the SWIM Faults (SWIM is the acronym of the ESF EuroMargins project “Earthquake and Tsunami hazards of active faults at the South West Iberian Margin: deep structure, high-resolution imaging and paleoseismic signature”) was mapped using a the new swath bathymetry compilation available in the area. The SWIM Faults form a narrow band of deformation over a length of 600 km coincident with a small circle centred on the pole of rotation of Africa with respect to Eurasia, This narrow band of deformation connects the Gloria Fault to the Rif-Tell Fault Zone, two segments of the plate boundary between Africa and Eurasia. In addition, the SWIM faults cuts across the Gulf of Cadiz, in the Atlantic Ocean, where the 1755 Great Lisbon earthquake, M~8.5-8.7, and tsunami were generated, providing a new insights on its source location.

ESONET proposes a network of sea floor observatories around the European Ocean Margin from the Arctic Ocean to the Black Sea for strategic long term monitoring as part of a GMES with capability in geophysics, geotechnics, chemistry, biochemistry, oceanography, biology and fisheries. Long-term data collection and alarm capability in the event of hazards (e.g. earthquakes) will be considered. ESONET will be developed from networks in key areas where there is industrial sea floor infrastructure, scientific/conservation significance (e.g. coral mounds) or sites suitable for technology trials (e.g. deep water close to land).

The tsunami generated by the 1755.11.01 earthquake, as reported by coeval sources, was the major event of its kind in the North Atlantic, until nowadays. The coasts of the Iberian Peninsula and Northwest Morocco were deeply affected by that phenomenon, with tremendous impacts on the city of Lisbon. For the last 20 years, significant support was received from EU (Projects DETWS, IAM, GITEC, GITEC-TWO and BIGSETS), national projects (MATESPRO, RIFANO and RIMAR) and bi-lateral cooperation (HITS, TTR-10, SISMAR and VOLTAIRE). This allowed significant improvements on the knowledge of parameters sources and tsunami propagation. Tsunami propagation models were developed, being the simulations controlled by real data, deducted from historical reports or instrumental networks. In order to assess the considerable impacts along the Portuguese coasts, different run-up models have been used and tested. To evaluate the tsunami hazard, comprehensive studies were developed, recognizing the importance of the inter-disciplinary approach, including the study of induced continental sedimentary deposits. The location of the 1755.11.01 source has been a key question, motivating intensive marine research in the southern area of Portugal, looking for unquestionable morphological or geological evidence of fault rupture and the present-day seismic activity.

23 pages, 12 figures.-- IGM contribution No. 1321, Southwest Portugal, the Gulf of Cadiz and Morocco are under the potential threat of natural hazards linked to seismicity and tsunami generation. We report the results of two multi-channel seismic (MCS) surveys carried out in 1992 and 1998 along the continental margin and oceanic crust of SW Iberia. This MCS data set shows the evidence of the compressional deformation which involves both the continental and the oceanic crust of the study area. The area of deformation extends from the southern border of the Tagus Abyssal Plain to the Seine Abyssal Plain, encompassing the continental margin of SW Portugal. Most of the structures observed are probably related to a Mid-Miocene phase of Africa-Europe plate convergence. In this paper we discuss the recent advances on the identification of the tectonic structures that are still active and that may generate great earthquakes and tsunamis. The tectonic structures identified are located respectively at the Guadalquivir Bank, along the eastern border of the Horseshoe Abyssal Plain and along the southern continental slope of SW Portugal, The research was funded by the EC Environment and Climate Program 1994–1998, Technologies to Forecast, Prevent and Reduce Natural Risks (contract n. ENV4-CT97-0547, project BIGSETS). Additional funding was supported by the Portuguese Project MATESPRO (PDCTM/P/MAR/15264/1999

Swath-bathymetry and acoustic-backscatter data from the southwest Iberian margin, which hosts the present-day boundary between the European and African plates, reveal the surficial expression of several fault structures

New seismic-reflection images across the eastern segment of the Azores-Gibraltar line west of the collisional area between the African and Iberian plates have revealed a complex pattern of compressional deformation involving the Mesozoic oceanic lithosphere. The compressional deformation developed in a region of slow plate convergence and is diffused, at different lithospheric levels, across an area spanning ∼200 km from the Gorringe Ridge to the Seine Plain. The convergence between the African and Iberian plates has been active since Tertiary time, and our results indicate that no subduction zone exists across this part of the plate boundary.