BUSCADOR RECOLECTA

19 pages, 4 figures, extended data figures and tables https://doi.org/10.1038/s41586-019-1784-0.-- The digitized values of P-wave seismic velocity above interplate boundary versus depth and seafloor depth along the 48 wide-angle seismic profiles used here are available at the public research data repository figshare (https://doi.org/10.6084/m9.figshare.9729302.v1).-- The scripts necessary to process the data and reproduce the main results and figures presented in this work are available at the public research data repository figshare (https://doi.org/10.6084/m9.figshare.9729302.v1), Seismological data provide evidence of a depth-dependent rupture behaviour of earthquakes occurring at the megathrust fault of subduction zones, also known as megathrust earthquakes1. Relative to deeper events of similar magnitude, shallow earthquake ruptures have larger slip and longer duration, radiate energy that is depleted in high frequencies and have a larger discrepancy between their surface-wave and moment magnitudes1,2,3. These source properties make them prone to generating devastating tsunamis without clear warning signs. The depth-dependent rupture behaviour is usually attributed to variations in fault mechanics4,5,6,7. Conceptual models, however, have so far failed to identify the fundamental physical causes of the contrasting observations and do not provide a quantitative framework with which to predict and link them. Here we demonstrate that the observed differences do not require changes in fault mechanics. We use compressional-wave velocity models from worldwide subduction zones to show that their common underlying cause is a systematic depth variation of the rigidity at the lower part of the upper plate - the rock body overriding the megathrust fault, which deforms by dynamic stress transfer during co-seismic slip. Combining realistic elastic properties with accurate estimates of earthquake focal depth enables us to predict the amount of co-seismic slip (the fault motion at the instant of the earthquake), provides unambiguous estimations of magnitude and offers the potential for early tsunami warnings, This work was done in the framework of projects ZIP (reference 604713), funded by the E.C. in the call for proposals FP7-PEOPLE-2013-ITN and FRAME (reference CTM2015-71766-R), funded by the Spanish Plan of Research and Innovation, Peer Reviewed

18 pages, 7 figures, supporting information https://doi.org/10.1029/2019TC005586.-- Data are available at the PANGAEA world data center https://doi.org/10.1594/PANGAEA.909047, We present a 2‐D P wave velocity model and a coincident multichannel seismic reflection profile characterizing the structure of the southern Costa Rica margin and incoming Cocos Ridge. The seismic profiles image the ocean and overriding plates from the trench across the entire offshore margin, including the structures involved in the 2002 Osa earthquake. The overriding plate consists of three domains: Domain I displays thin‐skinned deformation of an imbricate thrust system composed of fractured rocks. Domain II shows ~15‐km‐long landward dipping reflection packages and active deformation of the shelf sediment. Domain III is little fractured and appears to be dominated by elastic deformation, overlain by ~2‐km‐thick landward dipping strata. The velocity structure supports the argument that the bulk of the margin is highly consolidated rock. Thick‐skinned tectonics probably causes the uplift of Domains II and III. The oceanic plate shows crustal thickness variations from ~14 km at the trench (Cocos Ridge) to 6–7 km beneath the shelf. We combine (1) interplate geometry and fracturing degree, (2) tectonic stresses and brittle strain, and (3) earthquake locations, to investigate relationships between structure and earthquake generation. The 2002 Osa sequence nucleated at the leading flank of subducting seamounts in the area of highest tectonic overpressure. Both estimated rock fracturing and modeled brittle strain steadily increase from the leading flank of the subducting seamounts to their top, reflecting the progressive damage caused by the seamount. Therefore, the seismicity and structural‐mechanical evolution of the upper plate reflect the downward propagation of the leading edge of seamounts, This research was supported by E‐FIRE (PCIN‐2015‐053) and FRAME (CTM2015‐71766‐R) projects, as well as the People Programme (Marie Curie Actions) under REA Grant Agreement 604713 (ZIP “Zooming In between Plates”), Peer reviewed

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), Peer reviewed

19 pages, 8 figures, supporting information https://doi.org/10.1029/2020JB019854.-- Data Availability Statement. The WESTMED data are archived at PANGAEA repository (https://doi.pangaea.de/10.1594/PANGAEA.921252), GEBCO bathymetry grid (https://doi.org/10.5285/a29c5465‐b138‐234d‐e053‐6c86abc040b9), and SRTM bathymetry/topography grid (https://doi.org/10.5067/MEaSUREs/SRTM/SRTMGL1.003), In continental settings, seismic failure is generally restricted to crustal depth. Crustal structure is therefore an important proxy to evaluate seismic hazard of continental fault systems. Here we present a seismic velocity model across the Gibraltar Arc System, from the Eurasian Betics Range (South Iberian margin), across offshore East Alboran and Pytheas (African margin) basins, and ending onshore in North Morocco. Our results reveal the nature and configuration of the crust supporting the coexistence of three different crustal domains: the continental crust of the Betics, the continental crust of the Pytheas Basin (south Alboran Basin) and onshore Morocco, and a distinct domain formed of magmatic arc crust under the East Alboran Basin. The magmatic arc under the East Alboran Basin is characterized by a velocity structure containing a relatively high‐velocity lower crust (~7 km/s) bounded at the top and base by reflections. The lateral extension of this crust is mapped integrating a second perpendicular wide‐angle seismic profile along the Eastern Alboran basin, together with basement samples, multibeam bathymetry, and a grid of deep‐penetrating multichannel seismic profiles. The transition between crustal domains is currently unrelated to extensional and magmatic processes that formed the basin. The abrupt transition zones between the different crustal domains support that they are bounded by crustal‐scale active fault systems that reactivate inherited structures. Seismicity in the area is constrained to upper‐middle crust depths, and most earthquakes nucleate outside of the magmatic arc domain, This work is supported by the Cluster of Excellence “The Future Ocean”, within the framework of the Excellence Initiative by the Deutsche Forschungsgemeinschaft (DFG) on behalf of the German federal and state governments. Efforts benefitted from funding of the German Science Foundation (DFG Grants GR1964/12‐1, RA 925/2‐1+2‐2, and RE 873/17‐1). The TOPOMED cruise was part of the EUROMARGINS and TOPO‐EUROPE initiatives of the EUROCORES Programme of the European Science Foundation (ESF). This study benefitted from an EU Marie Skłodowska‐Curie Individual Fellowship to L. Gómez de la Peña (H2020‐MSCA‐IF‐2017 796013). The Spanish Science and Innovation Ministry funded C. R. Ranero through the project FRAME CTM2015‐71766‐R and G. Booth‐Rea through the project PID2019‐107138RB‐I00. This is a contribution of the Barcelona Center for Subsurface Imaging, Grup de Recerca 2017 SGR 1662, Generalitat de Catalunya, With the funding support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI), Peer reviewed

26 pages, 11 figures.-- Data Availability Statement; Images are available at the PANGAEA world datacenter (https://doi.pangaea.de/10.1594/PANGAEA.911309) (BGR, 2020), Rifted margins result from continental lithosphere extension, breakup, and transition to seafloor spreading by modes typically described by end‐member conceptual models. However, current geophysical data challenge these archetypes showing a more complex spectrum of rifting styles. Here, we integrate geophysical and geological observations to constrain the time and space evolution of the central South China Sea (SCS) rift system. We provide new insights into the continental extension mechanisms and continent‐ocean transition (COT) formation from a seismic transect parallel to the extensional direction of the central SCS rift system. We present 850‐km‐wide region of continental crust where distributed extensional deformation formed a pattern of lithospheric boudinage defined by seven 100‐ to 200‐km‐long structural segments. Each segment is formed by an 18‐ to 24‐km‐thick crust sector laterally thinning into an interboudin neck with ≤10‐km ultrathin crust (ß factors ~3.3–6.5). Drill and stratigraphic information support that extension continued at all six interboudin necks in the central SCS until ~23 Ma, when breakup by seafloor spreading propagation reached one of them. We propose that the seven segments evolved as discrete subsystems from early rifting to breakup. Structurally equivalent ultrathin crust grabens occur NE and SW of both SCS conjugate margins, supporting a 3D wide rift mode of deformation across the SCS rift system. The six ultrathin crust contemporaneous necks and the abrupt nature and location of the COT support that the breakup was not controlled by further continental lithospheric thinning but rather was determined by the seafloor spreading propagation toward the SW, Generalitat de Catalunya (Government of Catalonia). Grant Number: 2017SGR1662; Ministerio de Economia y Competitividad (Spain). Grant Number: CTM2015‐71766‐R; Xunta de Galicia (Goverment of Galicia), FEDER 2014–2020: ED431G 2019/07; Xunta de Galicia (Goverment of Galicia). Grant Number: ED481B‐2017/087, With the funding support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI), Peer reviewed

4 pages, figures, Quantitively predicting earthquakes and tsunamis is a long-standing goal for seismological research. The behaviour of earthquake ruptures is not fully understood, and the differences between shallow and deep earthquakes often lead to underpredictions of tsunamis as a secondary hazard. Dr Valentí Sallarès and Dr César R. Ranero of the Institute of Marine Sciences, CSIC, in Spain have developed a new model that improves knowledge of earthquake rupture behaviour based on their depth within the crust. With an improved understanding of the characteristics of earthquakes, better prediction of tsunamis is possible, ZIP (reference 604713), funded by the E.C. in the call for proposals FP7-PEOPLE-2013-ITN. FRAME (reference CTM2015-71766-R), funded by the Spanish Plan of Research and Innovation

This work has been carried out within Grup de Recerca Consolidat de la Generalitat de Catalunya “Barcelona Center for Subsurface Imaging” (2017 SGR 1662).-- 35 pages, 26 figures, 3 tables, Based on more than 4,500 km of new and re-processed multichannel seismic lines, high-resolution seafloor bathymetry, available well data, and basement dredge samples, we have re-evaluated the entire stratigraphy and the tectonic evolution of the Alboran and western Algerian basins. We have correlated the sediment units deposited since the beginning of the formation of the different sub-basins, and we present for the first time a coherent stratigraphy and large-scale tectonic evolution of the whole region. The results provide the information to test and refine models of the geodynamic evolution of the westernmost Mediterranean.
The data analysis supports an independent evolution of the sub-basins through the latemost Oligocene and Miocene, and a common Plio-Holocene evolution. The latemost Oligocene and Miocene evolution was controlled by the evolution of the Gibraltar subduction system. The oldest sedimentary unit is restricted to the West Alboran and Malaga basins depocenter that during the latemost Oligocene and early Miocene connected to some smaller marine basins currently uplifted and located onshore on the Betics range. Later, during the middle Miocene, the Habibas and Pytheas sub-basins formed a second depocenter on the North African margin. The different sedimentary units found in both depocenters, together with their different deformation patterns, support that the West Alboran-Malaga and the Habibas-Pytheas depocenters were separated by a major tectonic boundary. The early Tortonian initial arc magmatic activity produced the formation of new areas floored by a volcanic basement by the end of the late Tortonian, when the first sedimentary units deposited in the East Alboran sub-basin, and probably during the late Tortonian-early Messinian in the South Alboran sub-basin. Extension of the back-arc setting created oceanic crust flooring the Algero Balearic Basin. The extensional formation of the westernmost Mediterranean basins ended in the latemost Miocene. The western migration of the subduction system stopped and the convergence between the African and the European tectonic plates started to dominate the tectonic evolution of the region. During the Plio-Holocene, the sub-basins did not further subside individually so that these sediments have spread out across the whole Alboran Basin. A new tectonic contractional and strike-slip fault system developed that is active nowadays.
The integration of our results together with the most recent tomographic studies has been used to test and refine the existing kinematic models of the area. None of the existing models explains all our large-scale observations, The authors acknowledge support from the Spanish Ministry of Economy and Competitiveness through the Complementary Action ESF TopoEurope TOPOMED (CGL2008-03474-E/BTE) and National Project EVENT (CGL2006-12861-C02-02). This work was supported by the Spanish Ministry of Education, Culture and Sport through the FPU fellowship 2013–2017 to L. Gómez de la Peña (AP2012-1579), and benefitted from a Marie Skłodowska-Curie Individual Fellowship to L. Gómez de la Peña (H2020-MSCA-IF-2017 796013). C. R. Ranero is funded by the Spanish Science and Innovation Ministry project FRAME CTM2015-71766-R, E. Gràcia is funded by the Spanish Science and Innovation Ministry project “STRENGHT” PID2019-104668RB-I00, and G. Booth-Rea through the Spanish Science and Innovation Ministry Project PID2019-107138RB-I00/SRA (State Research Agency / 10.13039/501100011033) and the “Junta de Andalucia” Project P18-RT-36332.-- With the funding support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI), Peer reviewed

9 pages, 6 figures, supplementary information https://doi.org/10.1038/s43247-021-00216-5.-- Data availability: The bathymetric data used for tsunami simulations are available from GEBCO (https://www.gebco.net/data_and_products/gridded_bathymetry_data/). Detailed bathymetry used to generate Figs. 1 and 2 is published in Zitellini et al 28. The epicentral location of the seismicity shown in Fig. 1 is from the IGN Seismic Catalogue (https://www.ign.es/web/ign/portal/sis-catalogo-terremotos). The HAT fault plane needed to reproduce the tsunami simulation is available in the figshare repository: https://doi.org/10.6084/m9.figshare.14589315.-- Code availability: The code necessary to reproduce the Fig. 3 is available in the figshare repository: https://doi.org/10.6084/m9.figshare.14589315, The southwest Iberia margin is widely believed to have hosted the 1755 Great Lisbon earthquake and ensuing tsunami, one of the most destructive natural events in European history. Here we combine geophysical data and numerical tsunami modelling to investigate the source and mechanism responsible for this event. We find that an intra-plate, lithospheric¬-scale thrust fault located at the Horseshoe Abyssal Plain coincides with the location and focal mechanisms of the largest regional earthquakes and is likely to have suitable dimensions and fault-rock properties to account for the magnitude of the 1755 event. We present tsunami simulations with this fault as the source, and find that they reproduce reported tsunami energy propagation patterns, arrival-times and run up heights more successfully than other modelled sources. We propose that a reverse dip-slip mechanism on the northwest verging Horseshoe Abyssal plain Thrust, combined with the two-state mechanical behaviour of serpentinite, is the most likely candidate for the source of the 1755 Great Lisbon earthquake and for other recent large regional earthquakes, This work has been done in the framework of projects FRAME (CTM2015-71766-R) and INSIGHT (CTM2015-70155-R), both funded by the Spanish Plan of Research and Innovation, and has also had funding support of the “Severo Ochoa Centre of Excellence” accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI). First author’s work was done in the framework of the “Juan de la Cierva - Incorporación” fellowship IJCI-2017-33838, Peer reviewed

11 pages, 6 figures, supplementary materials https://advances.sciencemag.org/content/suppl/2021/08/02/7.32.eabg8659.DC1.-- Data and materials availability: All the seismic data used in this work are publicly available. The three MCS lines NIC20, NIC50, and SO107/NIC80 are available at NSF’s Marine Geoscience Data System (MGDS) repository (https://www.marine-geo.org/collections/#!/collection/Seismic), whereas the OBS data are available at the PANGAEA data repository: https://doi.pangaea.de/10.1594/PANGAEA.931715 for NIC20 and NIC50 and https://doi.pangaea.de/10.1594/PANGAEA.931695 for SO107/NIC80, Large earthquake ruptures propagating up to areas close to subduction trenches are infrequent, but when they occur, they heavily displace the ocean seafloor originating destructive tsunamis. The current paradigm is that the large seafloor deformation is caused by local factors reducing friction and increasing megathrust fault slip, or prompting the activation of ancillary faults or energy sources. As alternative to site-specific models, it has been proposed that large shallow slip could result from depth-dependent rock rigidity variations. To confront both hypotheses, here, we map elastic rock properties across the rupture zone of the MS7.0-MW7.7 1992 Nicaragua tsunami earthquake to estimate a property-compatible finite fault solution. The obtained self-consistent model accounts for trenchward increasing slip, constrains stress drop, and explains key tsunami earthquake characteristics such as long duration, high-frequency depletion, and magnitude discrepancy. The confirmation that these characteristics are all intrinsic attributes of shallow rupture opens new possibilities to improve tsunami hazard assessment, This work has been done in the framework of project FRAME (CTM2015-71766-R), funded by the Spanish Plan of Research and Innovation and has also had the funding support of the “Severo Ochoa Centre of Excellence” accreditation (CEX2019-000928-S) of the Spanish Research Agency [Agencia Española de Investigación (AEI)]. M.P. has been funded by the Beatriu de Pinós program of AGAUR–Generalitat de Catalunya, with grant no. 2017BP00170. S.R. has been partially supported by FONDECYT grant no. 1211105, Peer reviewed

20 pages, 12 figures, supporting information https://doi.org/10.1029/2021JB021711.-- Data Availability Statement: The authors do not use any new data. All data come from previously published sources, and are available through Gailler et al. (2009) and Moulin et al. (2015). The bathymetric grid is freely available as a .xyz file from the website of the EMODnet (https://www.emodnet-bathymetry.eu/). This is a contribution of the Barcelona Center for Subsurface Imaging that is a Grup de Recerca 2017 SGR 1662 de la Generalitat de Catalunya, The Gulf of Lions—Ligurian basin, in the Western Mediterranean, opened from the end of Oligocene to the Miocene as a back-arc basin driven by rollback of the Ionian slab. Geophysical surveys across the margin have explored the crustal structure and the continent-ocean transition (COT), but its location and petrological nature is still a matter of debate. Here, we apply joint refraction and reflection travel-time tomography that combines travel-times from multichannel seismic and wide-angle seismic data to provide improved constraints on the P-wave velocity structure of the sediment cover and the geometry of the top of the basement with respect to previous studies. Similar to earlier works, the velocity model shows three crustal domains, but their geometry and internal velocity differ. We identify a ∼100 km-wide domain of oceanic crust with an anomalously high upper crustal velocity possibly caused by porosity-canceling processes triggered by 7–8 km thick overlying sediment cover. The vertical velocity structure and the thickness of the oceanic crust are similar to back-arcs in the Pacific and the Western Mediterranean. In contrast to previous interpretations, we propose that this oceanic domain is confined between two domains of ultra-thin (4–5 km-thick) continental crust, and that the COT is <10 km wide on either side of the oceanic crust, The work by I. Merino was made with the support of scholarship number BES-2016-077786 in the framework of project FRAME with reference CTM2015-71766-R, funded by the Spanish Ministry of Science, Innovation and Universities. M. Prada receives support of the Beatriu de Pinós postdoctoral programme of the Government of Catalonia's Secretariat for Universities and Research of the Ministry of Economy and Knowledge with reference 2017BP00170. ICM has also had funding support of the “Severo Ochoa Centre of Excellence” accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI), Peer reviewed

22 pages, 9 figures, supporting information https://doi.org/10.1029/2021JB022629.-- Data Availability Statement: Seismic and gravity data were collected by Spanish R/V Sarmiento de Gamboa in 2018. High-resolution images of the data used in this article are available in Figshare public database (https://figshare.com/articles/figure/MCS-seismic-line-interpreted_pdf/14865480 and https://figshare.com/articles/figure/OBS_H-seismic-record-sections_pdf/14865483). The bathymetric grid is freely available as a.xyz file from the website of the EMODnet (https://www.emodnet-bathymetry.eu/) and Generic Mapping Tools (Wessel & Smith, 1995) was used in the preparation of this manuscript.-- This is a contribution of the Barcelona Center for Subsurface Imaging that is a Grup de Recerca 2017 SGR 1662 de la Generalitat de Catalunya, The West Iberia margin is the focus of intense research since the 1980s, with some of the most exemplary geophysical cross-sections and drilling expeditions. Those data sets have been used to create conceptual models of rifting used as a template to interpret margins worldwide. We present two collocated ∼350 km long lines of multi-channel seismic (MCS) streamer data and wide-angle seismic (WAS) data collected across the Tagus Abyssal Plain (TAP). We use travel-times of first arrivals identified at WAS and reflected seismic phases identified at both WAS and MCS records to jointly invert for the P wave velocity (Vp) distribution and the geometry of a sediment unconformity, the top of the basement, and the Moho boundary. The Vp model shows that the TAP basement is more complex than previously inferred, presenting abrupt boundaries between five domains. Domain I under the foot of the slope and Domain III under the abyssal plain display Vp values and gradients of thin continental crust. In between, Domain II displays a steep Vp gradient and high Vp values at shallow depth that support that basement is made of exhumed partly serpentinized mantle. Domain IV and Domain V, further oceanward, have oceanic crust Vp structure. The new results support an unanticipated complex rift history during the initial separation of Iberia and America. We propose a geodynamic scenario characterized by two phases of extension separated by a jump of the locus of extension, caused by the northward propagation of the oceanic spreading center during the J-anomaly formation, which terminated continental rifting, The Spanish Ministry of Science, Innovation and Universities funded the FRAME project (CTM2015-71766-R) and I. Merino Ph.D. (BES-2016-077786). M. Prada is supported by the Beatriu de Pinós postdoctoral programme of the Catalonia Government (2017BP00170). [...] With the institutional support of the “Severo Ochoa Centre of Excellence” accreditation (CEX2019-000928-S), Peer reviewed

14 pages, 13 figures, 1 table.-- This is a contribution of the Barcelona Center for Subsurface Imaging that is a Grup de Recerca 2017 SGR 1662 de la Generalitat de Catalunya, We present a generalized workflow to retrieve high-resolution P-wave velocity ( VP ) models of complex Earth’s subsurface structures from traditional marine near-vertical seismic reflection experiments. These records have typically offsets too short to map refraction phases and lack low-frequency information. The workflow is composed of three steps: 1) downward continuation (DC) of seismic records to the seafloor to recover diving wave information; 2) travel-time tomography (TTT) of first arrivals obtained from DC data, to retrieve a kinematically correct model; and 3) full-waveform inversion (FWI) of the original streamer dataset, starting with the model obtained with TTT and sequentially introducing higher wavenumber details into the model. We show that the TTT allows overcoming the issues associated with the nonlinearity intrinsic to FWI. We also disentangle envelope and phase from the waveform to choose the objective function most suitable for FWI. We assess the accuracy of initial models and predict the quality of the FWI results by quantifying the early arrival cycle skipping between original and simulated data. The efficiency of the workflow is tested with a challenging synthetic target model, containing vertical boundaries with strong velocity contrasts and velocity inversions embedded in a checkerboard-like pattern. We show that workflow steps 1) and 2) provide a TTT model that is not cycle skipped at the frequencies available in most marine seismic experiments and thus allow step 3) FWI to obtain high-resolution VP models of the subsurface using band- and offset-limited field datasets, traditionally collected in marine airgun and streamer acquisitions, This work has been done in the framework of project FRAME (Reference CTM2015-71766-R) and project ATLANTIS PID2019-109559RB-I00, funded by the Spanish Ministry of Research and Innovation and has also had the funding support of the Severo Ochoa Centre of Excellence accreditation (CEX2019-000928-S), of the Spanish Research Agency (Agencia Española de Investigación, AEI), Peer reviewed

Memoria de tesis doctoral presentada por Irene Merino Pérez para obtener el título de Doctora en Ciències de la Terra por la Universitat de Barcelona (UB), realizada bajo la dirección del Dr. César Rodríguez Ranero y del Dr. alentí Sallarès Casas del Institut de Ciències del Mar (ICM-CSIC).-- 217 pages, figures, tables, appendixes, In this PhD work, I carried out a geophysical and geological study of two classical examples of rifted continental margins: the Gulf of Lions, located in the Western Mediterranean, and the Tagus Abyssal Plain, located in the West Iberia margin. Despite the numerous previous studies performed in these two margins, there is an open debate on their crustal structure and on the processes that led to their formation. My study aims to 1) determining the nature of rocks forming the main geological domains of the basin based on a new methodological approach, 2) defining the tectonic structure of the basement and 3) placing constrains and discussing the kinematics and tectonic and magmatic mechanisms involved in the formation of these basins.
To study the Gulf of Lions and Ligurian basin, I used a geophysical data set acquired during the SARDINIA-2006 survey. It was conducted on board the French R/V L’Atalante, by the L'Institut Français de Recherche pour l'Exploitation de la Mer (Ifremer) (France). In particular, I used seismic records along three spatially consecutive Multi-Channel Seismic (MCS) lines and a collocated Wide-Angle Seismic (WAS) profile recorded by a set of Ocean Bottom Seismometers (OBS) during the shooting of the MCS lines. Altogether, these lines cover a 467-km-long seismic transect that runs NW-SE across the Gulf of Lions until the central part of the Liguro-Provençal basin. [...], The author of this thesis has benefited from a four-year “Formación de Personal Investigador” (FPI) fellowship (reference BES-2016-077786) in the framework of the FRAME project (reference CTM2015-71766-R), funded by the “Ministerio de Ciencia e Innovacion” (MICINN) between 2016 and 2021. The author carried out, within the framework of the FPI, a 3 months-stay at the Geophysics Section of the DIAS Dublin Institute for Advanced Studies (Dublin, Ireland).
For the first part of this thesis, the seismic data used in this study was collected by French R/V L’Atalante in 2006. We do not use any new data. All data come from previously published sources, and are available through (Gallier et al., 2009) and (Moulin et al., 2015). For the second part of the thesis, the data used was acquired within the framework of the FRAME project (reference CTM2015-71766-R) onboard of the R/V Sarmiento de Gamboa.
This work was carried out within the Grup de Recerca Consolidat de la Generalitat de Catalunya Barcelona Centre for Subsurface Imaging (B-CSI) (2014SGR940). The group computer and software facilities have been largely funded with the projects Kaleidoscope, CO-DOS, Geomargen-2, Geomargen-3, Geomargen-4, Geomargen-5, Geomargen-6, and CODOS-Phase2 funded by Repsol

20 pages, 19 figures, 1 table.-- Data Availability Statement: The original seismic images and maps used for this publication are available online (at https://doi.org/10.5281/zenodo.6350585, A poorly defined boundary between the Nubia and Eurasian plates runs along the Northern Tunisian continental margin. The Tunisia margin is deformed by a slow NW–SE trending convergence resulting in a diffuse deformation zone with scarce and scattered seismicity compared to the seismic activity into the neighboring regions to the east and west along the boundary. The area has been poorly studied and therefore its recent evolution is almost unknown, particularly offshore. Here, we present a structural analysis of the active tectonics in this submarine continental margin. The data used for this analysis are high-resolution bathymetric maps together with parametric echosounder images which have allowed to obtain a map of active faulting with unprecedented detail. The structural analysis supports a dominantly transpressive to compressive component of faulting, resulting from the current regional NW–SE trending compressive regime between plates. The North-eastern Domain of the study region contains the highest number of active faults with numerous pockmarks aligned along them. This study shows that the plate boundary across the North Tunisia margin is incipient and poorly developed, which may be due to the fact that deformation is partitioned over a large number of structures, each accommodating a small percentage of convergence, with the exception of the Hayat fault system. The Hayat reverse fault, striking WSW–ENE, is the largest fault system that comparatively may accommodate a greater amount of displacement, and is probably responsible for the uplift of the North-eastern Domain of the continental margin, Data collection and MC were supported by the project Geomargen-2 funded by REPSOL. The work was also supported by the EU project EMODnet-HRSM-2. Additional funding came from the Spanish Ministry of Science and Innovation projects: CTM2011-30400-C02-01 “HADES,” CGL2011-30005-C02-02 “SHAKE,” CTM2015-70155-R “INSIGHT,” PID2019-104668RB-I00 “STRENGTH,” CTM2015-71766-R “FRAME,” and PID2019-109559RB-I00 “ATLANTIS.” ICM has also had funding support of the “Severo Ochoa Centre of Excellence” accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI), Peer reviewed

This is a contribution of the Barcelona Center for Subsurface Imaging.-- 18 pages, 13 figures, 3 tables, 2 appendixes, supplementary data https://doi.org/10.1093/gji/ggac087.-- Data availability: The DC code is available online at GitHub repository: https://github.com/ejimeneztejero/DC, under the GNU general public license v3.0, The purpose of marine seismic experiments is to provide information of the structure and physical properties of the subsurface. The P-wave velocity distribution is the most commonly modelled property, usually by inversion of arrival times or waveform attributes. In wide-angle seismic reflection/refraction (WAS) experiments, arrival times of seismic phases identified in data recorded by ocean bottom seismometers (OBS) are used to image relatively deep structures. Most WAS experiments have relatively low redundancy and produce robust velocity models of limited resolution. The shallow subsurface is also commonly studied with multichannel seismic (MCS) data recorded by towed streamers, a technique that is highly complementary to WAS. In this case, the recording of refractions as first arrivals is limited primarily by the streamer length and by features like water depth and the velocity structure and, in general, most refractions are masked by reflections and noise. However, MCS data of variable quality are available in many regions where no other data exist and previous work has shown that these data can also be used to retrieve velocity models through traveltime and full waveform inversion provided that first arrival information is properly extracted from the record sections. The most widely used tool to extract refractions as first arrivals from MCS recordings is the so-called downward continuation technique, which is designed for redatuming streamer field data to the seafloor. In this new virtual configuration, the early refractions transform to seismic phases that are becoming visible as first arrivals from nearly zero offset, facilitating their identification and use in traveltime tomography. However, there is limited literature, let alone available codes, to be used with the available MCS data sets. This work presents a user-friendly open source HPC software for redatuming 2-D streamer field data to the sea bottom for any seafloor relief. The main ingredient is the acoustic wave equation used backwards in time, allowing first the redatuming of the receivers and then the redatuming of the sources. Assessment tools are provided to evaluate the information available after redatuming for specific data acquisition configurations. Also, we present a step-by-step analysis that defines the most important features that influence the quality of the virtual, redatumed recordings, The work has been partially supported by project FRAME with reference CTM2015-71766-R and project ATLANTIS (PID2019-109559RB-I00), funded by the Spanish Ministry of Science, Innovation and Universities. ICM has also received funding support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S) of the Spanish Research Agency (AEI), Peer reviewed

This is a contribution of the Grup de Recerca 2017 SGR 1662 ‘Barcelona Center for Subsurface Imaging’ of the Generalitat de Catalunya.-- 16 pages, 8 figures, supporting information https://doi.org/10.1093/gji/ggad163.-- Data Availability: Synthetic magnetic models were produced using the freely available MAGPRISM software (https://sites.google.com/view/markkussoftware/gravity-and-magnetic-software/magprism). Magnetic forward models were computed using the GMSYS modelling package of Oasis montaj™ from Seequent (research license).-- This is a pre-copyedited, author-produced PDF of an article accepted for publication in Geophysical Journal International following peer review. The version of record [insert complete citation information here] is available online at: https://doi.org/10.1093/gji/ggad163, About half of the rifted margins purportedly formed by extension with minor magmatism. The conceptual models of those magma-poor systems are greatly influenced by the continent-to-ocean transition structure of the archetypal magma-poor West Iberia Margin. In the past, interpretation of magnetic data of West Iberia has been used to constrain conceptual rifting models, including the structure of the transition from the exhumed mantle domain to the oceanic crust formed at a spreading centre. However, uncertainties on geophysical data were generally not considered leading to overdetailed interpretations. We use synthetic magnetic modelling to show that magnetic data acquired at sea level cannot resolve subhorizontal lithological layering in deep-water continental margins. We then present new magnetic modelling guided by a refined velocity model of the wide-angle seismic IAM-9 profile that shows that the magnetic J-anomaly correlates with oceanic crust that abuts exhumed mantle across a vertical boundary. This well-constrained observation supports that seafloor spreading initiated abruptly, terminating mantle exhumation. Conventional wisdom dictates that the sudden efficient melt extraction relates to a mechanical threshold during lithospheric thinning and concomitant asthenospheric upwelling under which melt can migrate toward the surface. However, our results support that mantle melting creating oceanic crust was probably not driven by gradual lithospheric thinning and asthenospheric upwelling, but by seafloor spreading centre propagation that cut across the lithosphere, creating the abrupt structure, MN acknowledges support from Fundação para a Ciência e Tecnologia, I.P./MCTES through national funds (PIDDAC)—projects LISA (PTDC/CTA-GEF/1666/2020), UIDB/50019/2020-IDL and PTDC/CTA-GEO/031885/2017. CRR was supported by project FRAME (CTM2015-71766-R), ATLANTIS (PID2019-109559RB-I00), funded by the Spanish Ministry of Science and Innovation and ‘Severo Ochoa Centre of Excellence’ (CEX2019-000928-S) of the Spanish Research Agency (AEI), Peer reviewed

European Geosciences Union General Assembly (EGU23), 24-28 April 2023, Vienna, Austria.-- 1 page, The conceptual models of magma-poor rifted margins are greatly influenced by the continent-to-ocean transition structure of the archetypal magma-poor West Iberia Margin. Some previous works with West Iberia magnetic data have been used to constrain the structure and interpret the transition from the exhumed mantle domain to the oceanic crust formed at a spreading center. However, it is found that the resolution uncertainty of the geophysical data was generally overlooked, leading to over-detailed interpretations. In this work we use synthetic magnetic modelling to show that magnetic data acquired at sea-level cannot resolve sub-horizontal lithological layering in deep-water continental margins. Then, we present a new magnetic model guided by a refined velocity model of the wide-angle seismic IAM-9 profile in the Iberia Abyssal Plain. This new model supports that the J-anomaly is caused by a ~6 km thick oceanic crustal structure with locally increased magnetization compared to regular oceanic crust. This J-anomaly crust abuts the exhumed mantle across a nearly vertical boundary, and is the oldest accreted oceanic crust. These results support that mantle exhumation was abruptly terminated by the accretion of oceanic crust. Mantle melting creating oceanic crust was probably not driven by gradual lithospheric thinning and asthenospheric upwelling, but may be the result of seafloor spreading center propagation cutting across the lithosphere and creating the abrupt structure, This work was funded by the Portuguese Fundação para a Ciência e a Tecnologia (FCT) I.P./MCTES through national funds (PIDDAC) – UIDB/50019/2020- IDL. Support from FCT (PTDC/CTA-GEF/1666/2020), Spanish Ministry of Science and Innovation (CTM2015-71766-R, PID2019-109559RB-I00) and Spanish Research Agency (CEX2019-000928-S) is also acknowledged, Peer reviewed

13 pages, 8 figures, 2 appendices, supplementary material https://dx.doi.org/0.5194/os-14-403-2018-supplement, The Alboran Sea is a dynamically active region where the salty and warm Mediterranean water first encounters the incoming milder and cooler Atlantic water. The interaction between these two water masses originates a set of sub-mesoscale structures and a complex sequence of processes that entail mixing close to the thermocline. Here we present a high-resolution map of the diapycnal diffusivity around the thermocline depth obtained using acoustic data recorded with a high-resolution multichannel seismic system. The map reveals a patchy thermocline, with spots of strong diapycnal mixing juxtaposed with areas of weaker mixing. The patch size is of a few kilometers in the horizontal scale and of 10-15ĝ€m in the vertical one. The comparison of the obtained maps with the original acoustic images shows that mixing tends to concentrate in areas where internal waves, which are ubiquitous in the surveyed area, become unstable and shear instabilities develop, enhancing energy transfer towards the turbulent regime. These results are also compared with others obtained using more conventional oceanographic probes. The values estimated based on the seismic data are within the ranges of values obtained from oceanographic data analysis, and they are also consistent with reference theoretical values. Overall, our results demonstrate that high-resolution seismic systems allow the remote quantification of mixing at the thermocline depth with unprecedented resolution., This work has been fulfilled in the framework of projects POSEIDON (ref: CTM2010-25169) and FRAME (ref: CTM2015-71766-R), both funded by the Spanish Ministry of Economy and Competitiveness (MINECO). The seismic and oceanographic data were acquired in the framework of the IMPULS survey (ref: 2003-05996-MAR), also from MINECO, and the SAGAS survey (ref: CTM2005-08071-C03-02/MAR-SAGAS). This work was also supported by the Grup de Recerca de la Generalitat de Catalunya: Barcelona Center for Subsurface Imaging (2014SGR940), Peer Reviewed

26 pages, 15 figures, tables, supporting information https://doi.org/10.1029/2017TC004946.-- All the data used are listed in the references or archived at the Barcelona‐CSI repository at the ICM (TOPOMED, EVENT‐DEEP, and ESCI cruises, http://www.icm.csic.es) and at the UTIG repository (CONRAD cruise, http://www.udc.ig.utexas.edu/sdc/).-- This work has been carried out within Grup de Recerca Consolidat de la Generalitat de Catalunya “Barcelona Center for Subsurface Imaging” (2017 SGR 1662), The Alboran Basin in the westernmost Mediterranean hosts the orogenic boundary between the Iberian and African plates. Although numerous geophysical studies of crustal structure onshore Iberia have been carried out during the last decade, the crustal structure of the Alboran Basin has comparatively been poorly studied. We analyze crustal-scale images of a grid of new and reprocessed multichannel seismic profiles showing the tectonic structure and variations in the reflective character of the crust of the basin. The nature of the distinct domains has been ground-truthed using available basement samples from drilling and dredging. Our results reveal four different crustal types—domains—of the Alboran Basin: (a) a thin continental crust underneath the West Alboran and Malaga basins, which transitions to (b) a magmatic arc crust in the central part of the Alboran Sea and the East Alboran Basin; (c) the North African continental crust containing the Pytheas and Habibas subbasins; and (d) the oceanic crust in the transition toward the Algero-Balearic Basin. The Alboran Basin crust is configured in a fore-arc basin (West Alboran and Malaga basins), a magmatic arc (central and East Alboran), and a back-arc system in the easternmost part of the East Alboran Basin and mainly Algero-Balearic Basin. The North African continental crust is influenced by arc-related magmatism along its edge and was probably affected by strike-slip tectonics during westward migration of the Miocene subduction system. The distribution of active tectonic structures in the current compressional setting generally corresponds to boundaries between domains, possibly representing inherited lithospheric-scale weak structures, The authors acknowledge support from the Spanish Ministry of Economy and Competitiveness through the Complementary Action ESF TopoEurope TOPOMED (CGL2008‐03474‐E/BTE), national projects EVENT (CGL2006‐12861‐C02‐02), INSIGHT (CTM2015‐70155‐R), FRAME (CTM‐2015‐71766‐R), and COST Action 1301 “FLOWS.” This work was supported by the Spanish Ministry of Education, Culture and Sport through the FPU fellowship 2013–2017 to L. Gómez de la Peña (AP2012‐1579). This publication is funded by the Cluster of Excellence “The Future Ocean,” within the framework of the Excellence Initiative by the Deutsche Forschungsgemeinschaft (DFG) on behalf of the German federal and state governments, Peer Reviewed

These data sets are associated with an article that is currently under review.-- Estos conjuntos de datos están asociados a un artículo que está actualmente en proceso de revisión, A new code for anisotropic traveltime tomography is presented. We describe the equations governing the anisotropic ray propagation algorithm and the modified inversion solver. This code can provide better understanding of the Earth's subsurface in the rather common geological contexts in which seismic velocity displays a weak dependency on the polar angle of ray propagation. We study the sensitivity of two medium parametrizations and compare four inversion strategies on a canonical model. The synthetic data sets for all these tests can be found in this repository directory, Project FRAME (Formation of geological domains in the Western Iberian Margin and tectonic reactivation of their limits), reference # CTM2015-71766-R, funded by the Spanish Ministry of Economy and Competitivity, Project SOUND (Seismic Modelling Using Natural Source Data) funded by Repsol, Table of contents • Inputs – All necessary input files. ◦ ani ◦ picks ◦ vel • Synthetic_Data – All synthetic data sets ◦ For_Sensitivity_and_Accuracy ▪ delta ▪ parallel_velocity ▪ epsilon ▪ parallel_velocity_finer ◦ For_Inversion_Tests • 3.1_Sensitivity – Sensitivity results ◦ 0.25pi_rad ◦ 0_rad • 3.2_Accuracy – Accuracy results ◦ 0.25pi_rad ◦ 0_rad ◦ overall_average • 3.3_Inversion_results – Inversion tests results ◦ Figure_5 ◦ Figure_6 ◦ Figure_7 ◦ Figure 8 • 3.4_Modeling_delta – Results for delta modeling tests ◦ Figure_9 ◦ Table_8-epsilon ◦ Table_9-epsilon ◦ Figure_10 ◦ Table_8-perpendicular_velocity ◦ Table_9-perpendicular_velocity • Supplementary – Files for supplementary figures ◦ FigS1 ◦ FigS2, Peer reviewed