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The dimensions, the geographical position and the complex geological history of the Iberian Peninsula makes it a unique and singular target to study its crustal and upper mantle structure and geodynamical evolution using geophysical methods. The lithospheric structure beneath Iberia has been investigated since the 1970’s using deep multichannel seismic reflection and refraction/wide-angle reflection profiling. Gravimetric and magnetic data were acquired following the deployment of permanent and temporary stations, mostly during the 1990’s. Beginning in the late 1990’s, the progressive use of Global Navigation Satellite Systems (GNSS) instruments contributed to monitor the present-day motions. During the last decades, numerous geological and geophysical surveys have investigated the Iberian lithosphere and upper mantle in the onshore and offshore regions, the most recent ones related to the TopoIberia project. The approach developed in this contribution is twofold. Firstly, we summarize the available geophysical information over Iberia, from focusing on the upper crust to the lithosphere-asthenosphere boundary and the transition zone marking the bottom of the upper mantle. Results of GNSS data, potential fields, controlled source seismic profiles, magnetotelluric data, body and surface wave tomography, receiver functions and 2D and 3D lithospheric modeling are reviewed and compared. Secondly, we focus on the areas of greater geodynamic interest and the regions where inconsistencies within the geophysical results, or contradictions in their tectonic interpretation exist, identifying the major questions that are still under debate. Besides shedding light to the state of knowledge and pointing out present-day research challenges, this review provides a tool for the integration of the diverse geophysical datasets with the surface geology and geodynamical processes that are interpreted to have built the complex geology of the Iberian Peninsula., The authors acknowledge funding from the Generalitat de Catalunya, grant/awards number AGAUR 2017SGR1022, and AGAUR 2017SGR847, the Spanish Ministry of Science, Innovation, and Universities grant numbers RTI2018-095594-B-I00, PGC2018-095154-B-100 and PGC2018-094227-B-I00 and the Spanish Ministry of Economy and Competitiveness grant numbers CGL2017-84901-C2 and PIE-CSIC-201830E039. IP is funded by the Spanish Ministry of Science, Innovation, and Universities and University of Salamanca grant BEAGAL18/00090. AV acknowledges funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S).

The structure and geodynamics of the southern margin of the Bay of Biscay have been investigated from a set of 11 multichannel seismic reflection profiles, recorded also at wide angle offsets in an onshore-offshore network of 24 OBS/OBH and 46 land sites. This contribution focuses on the analysis of the wide-angle reflection/refraction data along representative profiles. The results document strong lateral variations of the crustal structure along the margin and provide an extensive test of the crustal models previously proposed for the northern part of the Iberian Peninsula. Offshore, the crust has a typical continental structure in the eastern tip of the bay, which disappears smoothly towards the NW to reach crustal thickness close to 10 km at the edge of the studied area (~ 45°N, 6°W). The analysis of the velocity-depth profiles, altogether with additional information provided by the multichannel seismic data and magnetic surveys, led to the conclusion that the crust in this part of the bay should be interpreted as transitional from continental to oceanic. Typical oceanic crust has not been imaged in the investigated area. Onshore, the new results are in good agreement with previous results and document the indentation of the Bay of Biscay crust into the Iberian crust, forcing its subduction to the North. The interpreted profiles show that the extent of the southward indentation is not uniform, with an Alpine root less developed in the central and western sector of the Basque-Cantabrian Basin. N-S to NE-SW transfer structures seem to control those variations in the indentation degree. © 2017 Elsevier B.V., This work was carried out with the support of the MARCONI (REN2001-1734) project from Spanish MCYT. M.R. benefited from a PhD from the Spanish MCYT. This work was supported also by the Consolider-Ingenio 2010 Programme, under project CDS2006-0041 “Topo-Iberia”, TopoMed CGL2008-03474-E/BTE and Spanish Ministry of Economy and Competitiveness Project MISTERIOS (CGL2013-48601-C2-2-R)., postprint

This research was funded by the U.S. National Science Foundation EAR- 0808939. The deployment of the IberArray broadband seismic network is part of the CONSOLIDER-Ingenio 2010 TOPO-IBERIA (CSD2006-00041: Geosciences in Iberia: Integrated studies on Topography and 4-D Evolution) grant from the Spanish Ministry of Science and Innovation. Additional funding was provided by the Spanish ministry under grants CGL2010-17280, CGL2006-01171,CGL2009-09727, and CGL2007-63889,and by Generalitat de Catalunya under grant 2009 SGR 6.

Two passive seismic profiles have been acquired in the eastern Pyrenees as part of the Pyrope and Orogen projects to investigate the crustal structure differences between this area and the central and western Pyrenees. Up to 28 broad-band stations were deployed along two orthogonal lines, with an interstation spacing close to 10 km. High frequency receiver functions allowed us to obtain the main lithospheric interfaces along those lines. The NNE-SSW profile shows a well-defined Moho beneath Iberia, slightly deepening northwards. Beneath the Axial zone the Moho appears to be segmented but does not show evidence of crustal imbrication. Further North, the Moho appears again as a continuous interface located around 30 km depth. This image clearly differs from the conspicuous imbrication between the Iberian and Eurasian crusts observed westward. The E-W profile shows a smooth Moho thinning from a 40 km depth to the west of the profile to 23 km close to the coastline, evidencing the crustal thinning related to the Neogene extensional processes. Additional constraints on the geometry of the crust/mantle boundary in the Eastern Pyrenees are obtained from local moderate magnitude earthquakes recorded along the seismic lines during the experiment. In particular, a fan profile built from an event located near the Mediterranean coast suggests that crustal thickness differences between Iberian and Eurasian crusts can still be recognized 30 km westward of the Mediterranean coast, in an area that seems to mark the limit between regions dominated by compressive and extensive processes. We propose a model in which the observed dissimilar Moho structure beneath the Eastern Pyrenees is interpreted as the result of a different Mesozoic pre-shortening margin configuration. Seismic results are consistent with recently proposed tectonic models including an intermediate continental block separating Iberia and Europe by two basins with extremely thin crust or exhumed mantle., This work was funded by the Spanish Ministry of Economy and Competitiveness Project MISTERIOS (CGL2013-48601-C2-2-R), with additional support from the Generalitat de Catalunya grant 2017SGR1022 and projects ALPIMED (PIE-CSIC-201530E082) and SUBTETIS (PIE-CSIC-201830E039). The PYROPE experiment was supported by the French Research Agency ANR blanc programme (project PYROPE, ANR-09-BLAN-0229).

We studied the attenuation of coda waves and its frequency and lapse-time dependence in northern Morocco. We analysed coda waves of 66 earthquakes recorded in this region during 2008 for four lapse time windows of length 30, 40, 50, and 60 s, and at five frequency bands with central frequency in the range of 0.75–12 Hz. We determined the frequency dependent Q relation for the horizontal (NS and EW) and vertical (Z) component seismograms. We analyzed three-component broadband seismograms of 66 local earthquakes for determining coda-Q based on the single back-scattering model. The Q values show strong frequency dependence in 1.5–12 Hz that is related to high degree of heterogeneity of the medium. The lapse time dependence of Q shows that Q (Q at 1 Hz) significantly increases with lapse time that is related to the depth dependence of attenuation and hence of the level of heterogeneity of the medium. The average frequency-dependent Q(f) values are Q= (143.75 ± 1.09) f, Q= (149.12 ± 1.08) f and Q= (140.42 ± 1.81) f for the vertical, north–south and east–west components of motion, respectively. The frequency-dependent Q(f) relations are useful for evaluating source parameters (Singh et al. 2001), which are the key inputs for seismic hazard assessment of the region.

[EN] EPOS (European Plate Observation System) (https://www.epos-ip.org/) is now established as the only European multidisciplinary and global research infrastructure in Earth Sciences. It integrates several hundred national observatories for the observation and measurement of the internal and dynamic structure of the planet, and in particular in Europe, distributed in 25 European countries, including Spain. The EPOS project, included in the 2008 ESFRI Roadmap, has been recognized by ESFRI in 2016 as a priority project for its implementation, because of its strategic relevance in the European Research Area., [ES] EPOS (European Plate Observation System) (https://www.epos-ip.org/) se constituye actualmente como la única Infraestructura europea de Investigación multidisciplinar y global en Ciencias de la Tierra. Integra varios cientos de observatorios nacionales para la observación y medición de la estructura interna y dinámica del planeta, y en particular en Europa, distribuidos en 25 países de Europa, entre ellos España. El proyecto EPOS, incluido en la Hoja de Ruta ESFRI de 2008, ha sido reconocido por ESFRI en 2016 como proyecto prioritario para su implementación, por su relevancia estratégica en el ERA (European Research Area)., Este trabajo ha sido sufragado por los proyectos EPOS Implementation Phase (EPOS IP) (Grant agreement no:676564-EPOS IP) del EU VII Framework Program, ESFRI y Red Temática “EPOS ESPAÑA” (CGL2016- 81965-REDT) y Clúster de cálculo y servicio en remoto del nodo español de EPOS Espacio (UCMA15-EE3294), del Ministerio de Economía, Industria y Competitividad, España.

Whereas subduction recycling of oceanic lithosphere is one of the central themes of plate tectonics, the recycling of continental lithosphere appears to be far more complicated and less well understood(1). Delamination and convective downwelling are two widely recognized processes invoked to explain the removal of lithospheric mantle under or adjacent to orogenic belts(2-5). Here we relate oceanic plate subduction to removal of adjacent continental lithosphere in certain plate tectonic settings. We have developed teleseismic body wave images from dense broadband seismic experiments that show higher than expected volumes of anomalously fast mantle associated with the subducted Atlantic slab under northeastern South America and the Alboran slab beneath the Gibraltar arc region(6,7); the anomalies are under, and are aligned with, the continental margins at depths greater than 200 kilometres. Rayleigh wave analysis(8,9) finds that the lithospheric mantle under the continental margins is significantly thinner than expected, and that thin lithosphere extends from the orogens adjacent to the subduction zones inland to the edges of nearby cratonic cores. Taking these data together, here we describe a process that can lead to the loss of continental lithosphere adjacent to a subduction zone. Subducting oceanic plates can viscously entrain and remove the bottom of the continental thermal boundary layer lithosphere from adjacent continental margins. This drives surface tectonics and pre-conditions the margins for further deformation by creating topography along the lithosphere-asthenosphere boundary. This can lead to development of secondary downwellings under the continental interior, probably under both South America and the Gibraltar arc(8,10), and to delamination of the entire lithospheric mantle, as around the Gibraltar arc(11). This process reconciles numerous, sometimes mutually exclusive, geodynamic models proposed to explain the complex oceanic-continental tectonics of these subduction zones(12-17), This research was supported by US National Science Foundation grants EAR 0003572, 0607801 and 0808939 (A.L.), EAR 0808931 (E.D.H.), EAR 0809023 and 1054638 (M.S.M.), the Venezuelan National Fund for Science, Technology and Innovation grant G-2002000478 and PDVSA-INTEVEP-FUNVISIS cooperative agreement 2004-141 (M.S.), the Spanish Ministry of Science and Innovation grants CSD2006-00041, CGL2009-09727 and CGL2010-15146 (J.G. and R.C.), and by an A. v. Humboldt Foundation Research Prize (A.L.).

The Cantabrian Mountains have been interpreted as a Paleozoic basement block uplifted during an Alpine deformation event that led to the partial closure of the Bay of Biscay and the building of the Pyrenean range in the Cenozoic. A detailed interpretation of deep seismic reflection profile ESCIN-2 and the two-dimensional seismic modelling of the data allowed us to construct a N-S geological cross section along the southern border of the Cantabrian Mountains and the transition to the Duero Cenozoic foreland basin, highlighting the Alpine structure. The proposed geological cross section has been constrained by all geophysical data available, including a 2-D gravity model constructed for this study as well as refraction and magnetotelluric models from previous studies. A set of south-vergent thrusts dipping 30 to 36° to the north, cut the upper crust with a ramp geometry and sole in the boundary with the middle crust. These thrusts are responsible for the uplift and the main Alpine deformation in the Cantabrian Mountains. A conspicuous reflective Moho shows that the crust thickens northwards from the Duero basin, where subhorizontal Moho is 32 km deep, to 47 km in the northernmost end of ESCIN-2, where Moho dips to the north beneath the Cantabrian Mountains. Further north, out of the profile, Moho reaches a maximum depth of 55 km, according to wide-angle/refraction data. ESCIN-2 indicates the presence of a tectonic wedge of the crust of the Cantabrian margin beneath the Cantabrian Mountains, which is indented from north to south into the delaminated Iberian crust, forcing its northward subduction. © 2016 Author(s)., This study was part of the PhD thesis of J. Gallastegui and was supported by a FPU grant and research projects GEO 90-0660-1086 and PB92-1013 funded by CICYT (Committee of Science and Technology of the Spanish Ministry of Education and Science) and FICYT (Foundation for the Science and Technologic Research, Government of Asturias, Spain). Part of the study has also been financed by the Spanish Ministry of Science through the “TOPOIBERIA” Consolider Project (ref:MEC-06-CSD2006-0041) and the MISTERIOS Project (ref:MINECO-13-CGL2013-48601-C2).

The complex tectonic interaction processes between the European and African plates at the Western Mediterranean have left marked imprints in the crustal architecture of this area, particularly concerning the lateral variations in crustal thicknesses. The detailed mapping of such variations is hence of large interest, as it provides a major constraint to geophysical and geodynamic modeling at different scales. Controlled-source seismic profiling and receiver functions from natural seismicity are widely considered as major tools to constrain Moho topography. We compile here the Moho depths determined from a comprehensive number of both types of seismic surveys, to end up with a new 3D Moho depth map of the Iberian Peninsula, its continental margins and North Morocco. Since the 1970s, the lithospheric structure beneath this study area has been extensively investigated using multichannel normal incidence seismic reflection and refraction/wide-angle reflection profiling. In the last few years some high-resolution surveys at sea and inland have been acquired, the latter ones involving ~. 1000 land stations. On the other hand, the TopoIberia-IberArray experiment has triggered the investigations on crustal and lithospheric structure using natural seismicity, providing a homogeneous spatial resolution never achieved before. The availability of good quality results from both methodologies in a common area provides an excellent opportunity to check the consistency of the Moho depth estimations. The integration of both datasets has resulted in a new, high resolution map of the crustal thickness variations. The final grid evidences large Moho topography variations, including crustal imbrication in the Pyrenean range, a large and relatively undisturbed Variscan Massif in the center of Iberia and a probable delamination process beneath the Gibraltar Arc. The crustal thicknesses vary from ~. 15. km in continental margins up to values exceeding 50. km beneath the Pyrenees or the Rif Cordillera. © 2016., Funding for this project has been available from Spanish Ministry of Science and Innovation under grants: CGL 2014-09727, CGL2014-54582-REDC (RedTopoIberia), CGL2009-09727 (RIFSIS), CSD 2006-00041 (TopoIberia), CGL2007-63889 (SIMA), CGL2008-3474 (TopoMed), and by Generalitat de Catalunya grant 2009SGR1595. We have also used data from the PICASSO project, funded by the U.S. NSF grant EAR0808939, the Morocco Münster project funded under grant DFGTH1530/5-1, the WILAS project funded by the Portuguese Fundação para a Ciência e Tecnologia (PTDC/CTE-GIX/097946/2008) and the PYROPE experiment supported by the French Research Agency ANR blanc program (project PYROPE, ANR-09-BLAN-0229).

In the last decades, active seismic profiling in the northern part of the Iberian Peninsula has evidenced that the Alpine collision between the Iberian and Eurasian plates resulted in a complex crustal structure, with the Iberian crust underthrusting the Eurasian crust and reaching depths of at least 45-50. km beneath the Pyrenean chain and the Cantabrian Mountains. In the transition between these two zones the situation is particularly complex, as evidenced in previous wide-angle and passive seismic studies. This contribution focuses in getting new clues on the crustal structure of this transitional zone through receiver function (RF) analysis of teleseismic data recorded at permanent and temporary stations located in both the Spanish and French sides of the Western Pyrenees. Different techniques (H-κ stacking, pseudo-migration, synthetic 2D modeling) have been considered in the analysis. Passive seismic data from previous temporary deployments in the zone have been reworked and added to the discussion. A first order result is that passive seismic data are broadly consistent with the indentation of the Iberian and Eurasian crusts inferred from active seismic profiling, thus providing a completely independent confirmation of this feature. For the first time, an Iberian Moho underlying the Eurasian crust is documented from RF beneath the stations located at the Northern side of the Pyrenean range. Moreover, clear indications of dipping interfaces are observed at some stations. The new RF results suggest that in the crustal indentation beneath the Basque Massifs area, the Eurasian crust extends farther south with respect to the image inferred from active seismic data. This new geometry implies that the Pamplona transfer zone has played a major role in the regional geodynamic history. © 2012 Elsevier B.V., Most of the figures were created using GMT software (Wessel and Smith, 1998). This is a contribution of the Consolider-Ingenio 2010 project TOPO-IBERIA (CSD2006-00041).

Seismic data acquisition for the MARCONI project took place in 2003 in the eastern half of the Bay of Biscay. The overall goal of the multichannel experiment was to collect seismic data to elucidate the structure and evolution of the southern margin of the Bay where an along-the-margin transition between oceanic subduction in the west and continental convergence in the east occurs, and its relationship to the Pyrenean realm. We describe the multichannel experiment and present an interpretation of the abyssal plain sector of the profiles. Altogether, eleven regional seismic reflection profiles were collected with a total length of 1800. km, between the longitudes 6° and 2°W and latitudes 43.5° and 46°N. The seismic profiles show first images of the thick sedimentary pile that covers the eastern abyssal plain of the Bay. The interpretation includes three sedimentary sequences separated by unconformities that correspond to the pre-, syn- and post-Alpine sequences. The post-orogenic deposits lay unconformably over the previous compressional structures in the eastern part of the Bay, floored by transitional crust. These compressional features are evident in the presence of a young accretionary prism sealed at its first stages of development. The overall structure and shape is similar to those of active subduction prisms worldwide, but evidencing differences in width and sediment wedge thickness from west to east along the margin. Buoyancy of the transitional crust and resistance to subduction led to stronger plate coupling towards the east, where oceanic crust is absent, and may be the main cause for these morphological changes along the east-west traverse of the wedge. The MARCONI multichannel deep seismic dataset provides the first estimation of the thickness of the sediment load on the 5000. m deep abyssal plain of Bay of Biscay, where no direct data were available. © 2010 Elsevier B.V., We wish to thank the MARCONI Team and crew of R/V “Bio Hespérides” during the acquisition of the data and the Ministry of Education of Spain for financing the MARCONI Project: REN2001-1734-C03. GFV has a “Ramon y Cajal” contract co-financed between the ministry and the University of Oviedo through the European Social Funds. Part of this work was also supported by the Consolider-Ingenio 2010 Programme, under project CDS2006-0041, “Topo-Iberia”.

Earth Sciences are rapidly changing from largely descriptive to process-oriented disciplines that aim at quantitative models for the reconstruction and forecasting of the complex processes in the Solid Earth. Prediction is highly relevant for the basic needs of humanity: supply of water and resources, protection against natural hazards and control on the environmental degradation of the Earth. Intensive utilization of the human habitat carries largely unknown risks of and makes us increasingly vulnerable. There is an urgent need for scientifically advanced "geo-prediction systems" that can accurately locate subsurface resources and forecast timing and magnitude of natural hazards. The design of such systems is a major multidisciplinary scientific challenge. The quantitative understanding of the Earth has made significant progress in the last few decades. Important ingredients in this process have been the advances made in seismological methods to obtain information on the 3D structure of the mantle and the lithosphere, in the quantitative understanding of the lithospheric processes as well as the recognition of the key role of quantitative sedimentary basin analysis in connecting temporal and spatial scales. Quantitative understanding of the mass transfer by erosion and deposition as well as their feed back with crustal and subcrustal dynamics presents a new frontier in modern Earth sciences. This research bridges investigations on high-resolution, near-surface time scales and the large-scale, long-term approaches characteristic for the lithosphere and basin-wide studies. The essential step towards a 4D approach (in space and time) is a direct response to the need for a full incorporation of geological and geophysical constraints in the modelling of solid Earth processes. TOPO-EUROPE is a multidisciplinary international research program that addresses the interaction of processes inherent to the deep Earth (lithosphere and mantle) with surface processes (erosion, climate and sea level), which together shaped the topography of Europe. The objective of this programme is to quantify natural hazards by incorporating data interactive modelling focused on the lithosphere memory and neotectonics, with special attention on the thermo-mechanical structure of the lithosphere, mechanisms controlling large-scale plate boundaries and intraplate deformations, anomalous subsidence and uplift, and links with surface processes and topography evolution. © 2010 Elsevier B.V.

SUMMARY Stacks of ambient noise cross-correlations are more and more routinely used to extract empirical Green's functions between station pairs. The success of the cross-correlations is due to waves which are recorded by both stations and that constructively sum at lag times which equal their propagation time between the station pair. Stacking cross-correlograms corresponding to different time spans improves the azimuthal noise coverage and further enhances the signals. Here we show how the instantaneous phase coherence can be used for a more efficient signal extraction from ambient noise cross-correlations. The instantaneous phase coherence is obtained by analytic signal processing and can be employed through the phase cross-correlation and/or through the time-frequency domain phase-weighted stack. The phase cross-correlation is more sensitive to waveform similarity but less sensitive to strong amplitude features than the conventional cross-correlation. The time-frequency domain phase-weighted stack cleans the ambient noise cross-correlograms by attenuating incoherent noise and permits an improved signal identification. We show that both approaches are powerful tools in the recovery of signals from ambient noise data and show examples where they improve the extraction of P and Rayleigh waves by considering local and global scale applications.

The characteristics of the background seismic noise recorded at the IberArray broadband seismic network have been analyzed using power spectral den-sity estimates and their corresponding probability density functions (PDFs). The net-work is composed of 55 stations that have been deployed in southern Iberia and northern Morocco beginning in the summer of 2007. PDFs provide a useful tool for monitoring the network performance, allowing identification of stations with anomalously high noise levels. They can also be used to investigate the major sources of noise at different frequency bands and the seismic background noise variations related to time of day, season, weather, location, and type of installation. At high frequencies (>1 Hz), the main contribution seems to arise from the cultural noise, and therefore significant variations are observed between noise levels at dif-ferent stations based on proximity to populated areas. At microseismic frequencies (0.05-1 Hz), the noise level is more uniform among stations, although sites along the Gulf of Cádiz show a slightly increased level. At long periods, the vertical com-ponent noise level usually lies 15 dB above the new low-noise model and the horizontal components are much noisier, sometimes exceeding the new high-noise model for periods longer than 20 sec. Infragravity waves can be identified along the network for periods close to 100 sec, even for stations located inland. The dis-tribution of the median noise levels across the IberArray network shows a clear correlation with major geological features, such as the Guadalquivir and Gharb sedimentary basins, where noise is high, and the Iberian Massif where the noise levels are lowest. Among the main temporal variations observed we can highlight the diurnal differences in the noise level, particularly significant for high frequencies, and the noise level variations correlated to the significant wave heights in the surrounding water bodies., This is a contribution of the Team Consolider-Ingenio 2010 TOPO-IBERIA (CSD2006-00041). Additional funding is provided by the SIBERIA project (CGL2006-01171).

We present here an updated compilation of crustal parameters beneath the Iberian Peninsula and surrounding waters, inferred from extensive deep seismic exploration performed in the last three decades. Firstly, the more relevant experiments developed in both terrestrial and marine domains are revisited, together with the corresponding seismic velocity–depth models published that reveal the characteristics of the different tectonic domains sampled, including oceanic zones, continental margins, orogenic and rift belts. The results are summarized in three crustal transects sketched along representative directions. Secondly, we compiled the Moho depths along all the available seismic profiles to produce a geo-referred database. This database has then been interpolated using kriging algorithms to obtain a continuous Moho depth model, in the form of a regular grid file. This integrative Moho map for a key area in the Western Mediterranean documenting the interaction between European and African plates can contribute to constrain further regional studies, either at crustal, lithospheric or mantle scales. This is a contribution of the Team Consolider-Ingenio 2010 TOPO-IBERIA (CSD2006-00041). Additional founding provided by Generalitat de Catalunya (2005SGR00874) and by SIBERIA project (CGL2006-01171).

22 pages, 13 figures.-- Available online Nov 29, 2007.-- Issue title: "Geological characterization of the Galicia Bank Region (Atlantic Ocean, NW Iberia)"., An analysis of Cenozoic tectonics was carried out on the Galicia Bank Region by means of 750 km of single-channel and 155 km of multi-channel vertical seismic profiles and multibeam bathymetry. This work forms part of a general study aimed at determining the geological risk in the wreck area of the Prestige oil tanker. Several structures affecting the post-rift sedimentary units were identified: I) Faults inherited from the Lower Cretaceous propagating rift (reactivated and non-reactivated), including reactivated normal (N–S, NW–SE) and transfer (NE–SW) faults; and II) Structures resulting from compressive episodes in the Paleogene to Upper Miocene and the Upper Miocene to the Present, including a) neotectonic normal faults decoupled from the basement structure, b) folds and flexures and c) reverse faults (NE–SW to ENE–SWS) related to the Bay of Biscay subduction, that are the most striking regional structures., The characterization of structural style, sedimentary post-rift unit deformation and morphological trends were used to carry out a detailed study of the morphostructure of the Galicia Bank Region. Six morphostructural provinces were differentiated, from E to W: 1) the Galicia Interior Basin related to a main graben; 2) the Transitional Zone, which is a horst and graben territory; 3) the Galicia Bank Main Horst; 4) the Half-Graben Domain; 5) the Deep Galicia Margin, whose structure shows rotated blocks; and 6) the Northwestern Flank, characterized by reverse faults. The Transitional Zone and the Galicia Bank provinces are assumed to be the two morphostructural provinces of the Galicia Bank marginal platform. The origin of the Cenozoic deformation must have been related to reactivation processes during the Pyrenean orogeny. We propose that the fault pattern observed in the study area is related to the phase of renewed Mesozoic fault activity. Polyphase extension in the rifting stage and Cenozoic movements have produced an extensional interference pattern that is evident in the physiography. The decouplage between basement tectonics and upper sedimentary unit tectonics suggests the presence of a viscous layer. A thrust-related main antiform related to the Bay of Biscay subduction is proposed to explain the origin of the Galicia Bank morphology., The research was supported by the project "Identification of Potential Geo-Environmental Risks and their Assessment in the Wreck Area of the Oil Tanker Prestige", and by the ERGAP (Ref. VEM 2003-20093-CO3) and MARCONI (Ref. (REN2001-1734 C03-01/M) Projects of the Spanish Interministerial Commission for Science and Technology (CICYT). We thank the crew of the RV Hespérides for their help in collecting the data, and the UTM-CSIC team for their assistance during the cruise. The research is also a contribution to the project CONSOLIDER-INGENIO 2010 CSD2006-0041-"TOPOIBERIA", and to the RNM-328 PAI group.

The aim of this paper is to present a study on the potential and limits of the -transform and its inverses. The S-transform is an extension of the short-time Fourier transform with characteristics of the wavelet transform. It is mostly used for time-frequency analyses. Two different inverse S-transforms have been presented in the literature. We explain why the most recent one is an approximation but a very good one. The level of approximation is calculated in this paper. We then discuss the relative merits of both inverses. A careful study enables us to show that, although both inverses are nearly exact in the infinite continuous domain, this is not true anymore in the practical finite discrete domain. Side effects are quantified, and typical examples are given. Time-frequency filtering is one of the main applications of the S-transform. We evaluate the effects that occur when using the S-transform and its inverses for filtering.

The knowledge of the anisotropic properties beneath the Iberian Peninsula and Northern Morocco has been dramatically improved since late 2007 with the analysis of the data provided by the dense TopoIberia broad-band seismic network, the increasing number of permanent stations operating in Morocco, Portugal and Spain, and the contribution of smaller scale/higher resolution experiments. Results from the two first TopoIberia deployments have evidenced a spectacular rotation of the fast polarization direction (FPD) along the Gibraltar Arc, interpreted as an evidence of mantle flow deflected around the high velocity slab beneath the Alboran Sea, and a rather uniform N100°E FPD beneath the central Iberian Variscan Massif, consistent with global mantle flow models taking into account contributions of surface plate motion, density variations and net lithosphere rotation. The results from the last Iberarray deployment presented here, covering the northern part of the Iberian Peninsula, also show a rather uniform FPD orientation close to N100°E, thus confirming the previous interpretation globally relating the anisotropic parameters to the LPO of mantle minerals generated by mantle flow at asthenospheric depths. However, the degree of anisotropy varies significantly, from delay time values of around 0.5 s beneath NW Iberia to values reaching 2.0 s in its NE corner. The anisotropic parameters retrieved from single events providing high quality data also show significant differences for stations located in the Variscan units of NW Iberia, suggesting that the region includes multiple anisotropic layers or complex anisotropy systems. These results allow to complete the map of the anisotropic properties of the westernmost Mediterranean region, which can now be considered as one of best constrained regions worldwide, with more than 300 sites investigated over an area extending from the Bay of Biscay to the Sahara platform., This is a contribution of the Consolider-Ingenio 2010 project TOPO-IBERIA [CSD2006-00041]. Additional funding is provided by projects RIFSIS [CGL2009-09727], Siberia [CGL2006-01171] and Topomed [CGL2008-03474-E/BTE, ESF-Eurocores 07-TOPOEUROPE-FP006]. The Portuguese research team was supported by the Fundação para a Ciência e Tecnologia through projects WILAS (PTDC/CTE-GIX/097946/2008) and AQUAREL (PTDC/CTE-GIX/116819/2010).

New tomographic images of the upper mantle beneath the westernmost Mediterranean suggest that the evolution of the region experienced two subduction-related episodes. First subduction of oceanic and/or extended continental lithosphere, now located mainly beneath the Betics at depths greater than 400 km, took place on a NW-SE oriented subduction zone. This was followed by a slab-tear process that initiated in the east and propagated to the west, leading to westward slab rollback and possibly lower crustal delamination. The current position of the slab tear is located approximately at 4°W, and to the west of this location the subducted lithosphere is still attached to the surface along the Gibraltar Arc. Our new P-wave velocity model is able to image the attached subducted lithosphere as a narrow high-velocity body extending to shallow depths, coinciding with the region of maximum curvature of the Gibraltar Arc, the occurrence of intermediate-depth earthquakes, and anomalously thick crust. This thick crust has a large influence in the measured teleseismic travel time residuals and therefore in the obtained P-wave tomographic model. We show that removing the effects of the thick crust significantly improves the shallow images of the slab and therefore the interpretations based on the seismic structure, This is a contribution of the Team Consolider-Ingenio 2010 TOPO-IBERIA (CSD2006-00041). Additional fundingwas provided by the SIBERIA (CGL2006-01171), RIFSIS (CGL2009-09727) and ALERTES-RIM (CGL2013-45724-C3-3-R) projects.

Consistent constraints of an over-thickened crust beneath the Rif Cordillera (N. Morocco) are inferred from analyses of recently acquired seismic datasets including controlled source wide-angle reflections and receiver functions from teleseismic events. Offline arrivals of Moho-reflected phases recorded in RIFSIS project provide estimations of the crustal thicknesses in 3D. Additional constraints on the onshore-offshore transition are inferred from shots in a coeval experiment in the Alboran Sea recorded at land stations in northern Morocco. A regional crustal thickness map is computed from all these results. In parallel, we use natural seismicity data collected throughout TopoIberia and PICASSO experiments, and from a new RIFSIS deployment, to obtain receiver functions and explore the crustal thickness variations with a H-κ grid-search approach. This larger dataset provides better resolution constraints and reveals a number of abrupt crustal changes. A gridded surface is built up by interpolating the Moho depths inferred for each seismic station, then compared with the map from controlled source experiments. A remarkably consistent image is observed in both maps, derived from completely independent data and methods. Both approaches document a large crustal root, exceeding 50. km depth in the central part of the Rif, in contrast with the rather small topographic elevations. This large crustal thickness, consistent with the available Bouguer anomaly data, favors models proposing that the high velocity slab imaged by seismic tomography beneath the Alboran Sea is still attached to the lithosphere beneath the Rif, hence pulling down the lithosphere and thickening the crust. The thickened area corresponds to a quiet seismic zone located between the western Morocco arcuate seismic zone, the deep seismicity area beneath western Alboran Sea and the superficial seismicity in Alhoceima area. Therefore, the presence of a crustal root seems to play also a major role in the seismicity distribution in northern Morocco., Funding for this project has been available from the Spanish Ministry of Science and Innovation under grants: CGL2009-09727 (RIFSIS), CSD 2006-00041 (TopoIberia), CGL2007-63889 (SIMA), and CGL2008-3474 (TopoMed), and by Generalitat de Catalunya grant: 2009SGR996. We have also used data from the PICASSO project, founded by the U.S. NSF grant EAR0808939.

The Iberian Chain is a Cenozoic intraplate thrust belt located within the Iberian plate. Unlike other belts in the Iberia Peninsula, the scarcity of geophysical studies in this area results in a number of unknowns about its crustal structure. The Iberian Chain crust was investigated by means of a NE-SW refraction/wide-angle reflection seismic transect and two magnetotelluric profiles across the chain, oriented along the same direction. The seismic profile was designed to sample the crust by means of three shots designed to obtain a reversed profile. The resulting velocity-depth model shows a moderate thickening of the crust toward the central part of the profile, where crustal thickness reaches values above 40. km, thinning toward de SW Tajo and NE Ebro foreland basins. The crustal thickening is concentrated in the upper crust. The seismic results are in overall agreement with regional trends of Bouguer gravity anomaly and the main features of the seismic model were reproduced by gravity modeling. The magnetotelluric data consist of 39 sites grouped into two profiles, with periods ranging from 0.01 s to 1000 s. Dimensionality analyses show significant 3D effects in the resistivity structure and therefore we carried out a joint 3D inversion of the full impedance tensor and magnetic transfer functions. The Mesozoic and Cenozoic basins along the Chain are well characterized by shallow high conductive zones and low velocities. Elongated conductors reaching mid-crustal depths evidence the presence of major faults dominating the crustal structure. The results from the interpretation of these complementary geophysical data sets provided the first images of the crustal structure of the Iberian Chain. They are consistent with a Cenozoic shortening responsible of the upper crust thickening as well as of the uplift of the Iberian Chain and the generation of its present day topography., Funding for the research was provided by the I + D + I research projects: BTE-2001-4993-E, CGL2008-04916, and by the Consolider-Ingenio 2010 programme, under CSD 2006-00041 “Topo-Iberia.”

[FR] L’analyse des isotopes du plomb est appliquée à trois dépôts métalliques caractéristiques de l’Âge du Bronze Final de la Péninsule Ibérique. Tous ont des analyses de composition. Ceux de la grotte de Muricecs (Lleida) et le village de Las Lunas (Tolède) ajoutent des données isotopiques inédites qui sont comparées avec celles déjà publiées d’un ensemble d’armes du dépôt de la Ría de Huelva (Huelva), l’un des dépôts les plus importants du Bronze Final de l’occident européen. Les analyses des isotopes du plomb nous orientent sur l’origine du métal avec lequel furent fabriquées les pièces découvertes dans chaque dépôt. Elles ne permettent pas toujours de localiser l’origine de la minéralisation à cause des limitations actuelles de l’information géologique de référence. Néanmoins, en nous basant sur des données concernant l’homogénéité ou non des métaux, elles ont permis de les dissocier de la typologie des objets, aidant ainsi à la valorisation des dépôts et leurs possibles fonctions. L’analyse élémentaire est peu utile dans ce cas parce que les métaux du Bronze Final de la Péninsule Ibérique sont très homogènes et avec très peu d’impuretés., [EN] Lead isotope analysis was applied to three representative Late Bronze Age hoards from the Iberian Peninsula, for all of which compositional analyses are available. Unpublished isotopic evidence from the cave of Muricecs (Lleida) and the settlement of Las Lunas (Toledo) are compared to the published results for weapons from the Ría de Huelva, one of the most important Late Bronze Age hoards from Western Europe. Lead isotope analysis can tell us the sources of the metal used to make the artifacts in each hoard. The limited number of geologic reference points makes it difficult to determine all of the ore sources, but the analyses do give us evidence about the degree of homogeneity of the metal in the artifacts. As a result, one can separate metallic composition from artifact typology and thereby evaluate how the hoards were formed and what their functions were. Elemental analysis is unsuitable for this purpose because Late Bronze Age metals from Iberia are very homogenous and have few impurities., Ce travail a été réalisé dans le cadre des projets : 2010RU0086 (Russian Foundation for Basic Research – CSIC : Provincias metalúrgicas euroasiáticas y europeas del II milenio a.n.e. : investigación de sus interacciones a partir de métodos científico-naturales, chercheur principal : MIMN) ; HAR2010-21105-C02-02 (Plan Nacional de I+D+I ; Relación entre materias primas locales y producción metalúrgica : Cataluña meridional como modelo de contraste, chercheur principal IMR) ; CSD-TCPCSD2007-00058 (Programa CONSOLIDER INGENIO 2010, Ministerio de Ciencia e Innovación)

We have determined the three-dimensional P-wave velocity structure of the crust and uppermost mantle beneath the Iberia-Africa collision zone using local earthquake tomography. We have inverted arrival times of first-arriving P phases listed in the bulletins of the Instituto Geográfico Nacional and phases picked by us on permanent stations of other regional networks and on temporary broadband stations deployed in the frame of the TOPO-IBERIA project. In total we have used 38,624 P-wave arrival times from 2362 local events recorded at 120 seismic stations. The most remarkable result is the imaging of a large high velocity body following approximately the western Alboran coastline, with a horizontal dimension of at least 200. km and extending in depth from the surface down to 24. km. This body, not imaged previously with this extent using seismic tomography, coincides with surface exposures of subcontinental mantle (peridotites) in Iberia and Africa and with a belt of positive gravity anomalies. We have also found a marked contrast in the seismic velocities of the middle and lower crust of the Alboran basin, coinciding with the location of the Trans-Alboran Shear Zone. We attribute this contrast to widespread magmatic intrusions in the eastern part of the basin, resulting in higher P-wave velocities than in the west. This contrast would also explain the different orientation of the Trans-Alboran Shear zone with respect to the surface features and faults in the Alboran basin. We also image thick crust beneath the Betics and Rif, accompanied by downgoing lithosphere of the Iberian foreland and Gulf of Cadiz beneath the Betic-Rif-Alboran system., This is a contribution of the Team Consolider-Ingenio 2010 TOPO-IBERIA (CSD2006-00041).Additional funding was provided by the SIBERIA (CGL2006-01171), RIFSIS (CGL2009-09727) and ALERTES-RIM (CGL2013-45724-C3-3-R) projects

During the last decade, a major target for several international research teams has been to improve the knowledge on the Geodynamics of the Iberian plate and surrounding domains. The complexity of this area and the scarcity of appropriate constraints had been evidenced by the very different evolutionary models proposed in past decades. Hence, the recent efforts to tackle the key questions and derive new conclusive constraints have been afforded through large-scale research approaches that combine expertise on geology, geophysics and geodesy. A pioneering example of joining forces for that aim was the Topo-Iberia initiative, launched by the Spanish funding agency in 2006 to gather along 8 yearsmore than 100 scientists fromdifferent Spanish universities and research institutions. Topo-Iberia has placed new knowledge and constraints to unravel the interaction between deep and surficial processes, following the approach of the coeval Topo-Europe program. It has also been a reference to encourage other international teams to collaborate with and promote research on specific topics, such as the Betic–Rif–Atlas system (Picasso initiative), the Pyrenean domains (Pyrope project), Portugal (Wilas project) or theWestern Mediterranean domain (Topo-Med project). Topo-Iberia has allowed a significant increase on the quality and amount of the scientific information/data available for the Iberian plate by acquisition, deployment and management of a technological observatory infrastructure platform, IberArray, consistingof highresolution multi-disciplinary Solid Earth acquisition systems (seismology, deformation-GPS and magnetotellurics), following in this sense the US-Earthscope approach. As an example of future scientific outcome that could only be afforded within such an integrative approach, one might mention a N–S geotransect of about 1500 km-long across the whole Iberian Peninsula and the Alboran–Rif–Atlas system, from the Cantabrian Continental Margin down to the Algerian-Sahara border, compiling all available geophysical and geological results and models, many of them achieved during this project. Topo-Iberia has enhanced even more the collaboration between the research teams developing experiments aimed at obtaining comprehensive subsurface maps of Europe with magnificent resolution, as the ones derived under the Iberian Peninsula and presented in this volume. The next step foreseen is the Alp-Array international initiative, focused at 4D seismic studies in the Alps and surrounding areas. This could be perceived as a movingwave for homogeneous, high-densitymonitoring across Europe, as expected in the former Euro-Array concept. In practice, networking has started in Iberia-Northern Morocco with IberArray, crossed the Pyrenees within Pyrope, and it is now moving North-Eastwards to cover the whole European continent. The subsequent expertise and data bases issued from such infrastructures should also be a key asset in integrative programs such as EPOS., This research received continued support from national and international scientific initiatives such as Topo-Iberia, Topo-Europe ILP and EPOS programmes. Partial funding is provided by project 'Red TopoIberia-IberArray', ref: CGL2014-54582-REDC.

Benford’s law (BL), also known as the first‐digit law, is an intriguing pattern in data sets, first discovered more than a century ago then forgotten and rediscovered in the twentieth century. This law establishes that the frequency of occurrence of the first digit in many real‐world data sets is not uniform, but instead favors the first digits. In particular, the occurrence of numbers starting with 1 and 2 is close to 30% and 18%, respectively, whereas numbers starting with 8 or 9 are close to 5%. This law was first formulated in the late nineteenth century by the Canadian–American astronomer and mathematician Simon Newcomb, who noticed that library books of logarithms were more thumbed in the first pages, those containing numbers starting with 1. He proposed a law stating that the probability of a digit N being the first digit of a number was equal to log(N+1)−log(N) (Newcomb, 1881). This law remained unnoticed for the scientific community for more than 50 years. In 1938, it was rediscovered by the engineer Frank Benford, who presented data collections from up to 20 different sources, including financial data, population of cities, or averages of the American baseball league, each of them satisfying the expected proportionality (Benford, 1938). His work became popular, and the rule finally took his name. Benford extended the rule to any arbitrary base of the logarithm and confirmed that it applies further than the leading digit., This is a contribution of the Geodyn project (MICINN ICTS2009-33). Additional support is provided by the TopoIberia (CSD2006-00041) and Misterios (CGL2013-48601-C2-1-R) projects.

9 pages.-- PACS: 43.60.Jn; 43.30.Sf; 43.80.Ka Data recorded during a temporary deployment of ocean bottom seismometers (OBSs) are used in this study to monitor the presence of fin whales around the array. In the summer of 2003, ten OBSs were placed 250 km from the NW coast of Iberia in the Galicia Margin, NE Atlantic Ocean for a period of one month. The recorded data set provided a large variety of signals, including fin whale vocalizations identified by their specific acoustic signature. The use of a dense array of seafloor receivers allowed investigation into the locations and tracks of the signal-generating whales using a seismological hypocentral location code. Individual pulses of different sequences have been chosen to study such tracks. Problems related to the correct identification of pulses, discrimination between direct and multiple arrivals, and the presence of more than one individual have been considered prior to location. Fin calls were concentrated in the last two weeks of the deployment and the locations were spread around the area covered by the array. These results illustrate that, besides its classical seismological aim, deployment of semipermanent seafloor seismic arrays can also provide valuable data for marine mammal behavior studies.

P and S velocity and attenuation estimates in the lower crust are obtained from a set of wide angle reflection-refraction profiles in the region of active tectonics at the NE edge of the Tibetan Plateau and discussed together with respect to similar data at its Himalaya-south Tibet edge. The quality factor is estimated in the lower half of the crust by accounting for the differential effect on amplitude-frequency observed between waves of different penetrations, and both in P and S modes. Attenuation values allow to exclude a significant proportion of partial melt and to estimate the homologous temperature, ratio of in situ to solidus absolute temperatures. The latter depend on the physical conditions being of dry, wet or dehydration melting, which are found different among the regions of the northern Bayan Har and northern Qang Tang boundaries between blocks, as well as the Tethyan-Himalayas, south of the Indus-Tsangpo suture. Their in situ temperatures differ also as estimated from their different Vp for a similar felsic composition. Joint measurement of several parameters, Vp, Vs, Qp and Qs reveals the composition, mineralogy, temperature and hydration conditions of the lower half of the thickened crust of Tibet that may be discussed in terms of evolution. The material presently in the thickened crust, even its lower part, has a felsic composition, upper to middle crustal lithology, and the temperature conditions estimated suggest that basic material that could have underlain it could be eclogitized and not appear anymore above the seismic Moho. Under northern Qang Tang, the felsic material in the lower half of the crust appears as hot and dry. Its burial may have occurred earlier or may have been moderate in the postcollisional phase. This is consistent with a model of indentation of the Qang Tang crust by an originally thinner Bayan Har crust to bring part of its crust to greater depth, suggested from imaging the crustal architecture. Under northern Bayan Har, the material in the lower half of the crust appears as felsic, at low temperature and not dry conditions. This is evidence that it has been transported from a shallower depth, and this recently enough not to be yet dehydrated and temperature equilibrated in a conductive geotherm. It supports a model of recent overriding of the middle crust of the north Kun Lun block to the north independently suggested from the image of crustal architecture. The Tethyan Himalayas case appears bracketed by these two cases in northern Tibet for Vp and temperature conditions, but shows highest attenuation in the lower crust that is colder but less dry than under northern Qang Tang. © 2005 Elsevier B.V. All rights reserved., This project was supported by the INSU-CNRS, the French Ministry of Research and Education, Paris, the French Embassy in Beijing and the Department of International Cooperation, Science Technology, Ministry of Land and Resources, Beijing.

The S-transform provides a framework for data-adaptive filters which take advantage of time-frequency localized spectra. These filters basically consist in a data transformation to the time-frequency domain, the data-adaptive weighting of the localized spectra, and a back transformation. We illustrate that the inverse S-transform of manipulated spectra not necessarily transforms the localized signals as expected from the imposed weighting. The time localization is not directly translated and spurious signals and noise can be generated. We discuss this problem and suggest a new inverse S-transform, which may be helpful to many applications to take more advantage of the time-frequency localization.

New wide-angle reflection and refraction seismic data provide constraints on the structure of the upper lithosphere, and test models of its evolution to raise the northeastern part of the Tibetan Plateau. Amplitudes observed for reflections from the crust mantle boundary are sufficiently large to suggest that there is no significant partial melt in the deep crust. The data show an increase of the crustal thickness between terranes from north of the Kun Lun Fault into the Qang Tang of central Tibet, and a contrast among their intracrustal images and compositions. In the north, P and S velocities are consistent with a dominantly felsic composition and show that only the upper crust thickened. South of the Kun Lun Fault a thicker crust made of two layers could result from the superposition of the originally thin crust of the Bayan Har terrane on the lower part of the crust of the domain to the north, which upper crust it shoved and thickened. Different modes of crustal thickening, either by thickening of individual layers or superpositions and imbrication among them appear to work jointly to raise the topography. © 2002 Elsevier Science B.V. All rights reserved., The data collection has been supported by the Chinese MGMR, French INSU-CNRS and Ministry for Education and Research, Spanish CSIC, French Embassy in Beijing.

The regional mantle flow beneath the westernmost Mediterranean basin and its transition to the Atlantic domain is addressed by inspecting the anisotropic properties of the mantle. More than 100 new sites, from the Variscan core of Iberia to the northern rim of the Western African Craton, are now investigated using the data provided by different temporary and permanent broad-band seismic arrays. Our main objective is to provide a larger regional framework to the results recently presented along the Gibraltar Arc in order to check the validity of the different geodynamic interpretations proposed so far. The significant variations in the retrieved anisotropic parameters suggest that different processes must be invoked to explain the origin of the observed anisotropy. Beneath the Variscan units of the Central Iberian Massif the new results show a moderate amount of anisotropy with fast polarization directions (FPD) oriented close to E-W. Those results can only be explained in terms of global mantle flow if models accounting for contributions from surface plate motion, net lithosphere rotation and density variations are taken into consideration. One of the major results presented is the significant number of good quality data without evidence of anisotropy ("nulls") observed beneath permanent stations in southern Portugal. Those "nulls" can be explained by the presence of a predominantly vertical mantle flow associated to large variations in the lithospheric thickness. Beneath the Gibraltar Arc the FPD show a spectacular rotation, evidenced by the results presented by Díaz et al. (2010) and Miller et al. (2013). Those results are reviewed here taking also into consideration the geodynamic modeling presented recently by Alpert et al. (2013) and other geophysical and geodetic results. Further South, the analysis of new broad-band stations installed in the Moroccan Meseta and the High Atlas show a small degree on anisotropy and a large number of "null" events, pointing again to the presence of vertical flow in the mantle. The results favor an asthenospheric origin related to present-day mantle flow for the anisotropy observed from the Variscan core of Iberia to the northern rim of the West African Craton. This flow is deflected around the high velocity slab beneath the Gibraltar Arc and seems affected locally by vertical flow associated to edge-driven convective cells. The presence of significant backazimuthal variations in the anisotropic parameters retrieved from single events suggests that a second order contribution from an anisotropic layer within the lithosphere may also exist.

The lithospheric structures beneath the Pyrenees, which holds the key to settle long-standing controversies regarding the opening of the Bay of Biscay and the formation of the Pyrenees, are still poorly known. The temporary PYROPE and IBERARRAY experiments have recently filled a strong deficit of seismological stations in this part of western Europe, offering a new and unique opportunity to image crustal and mantle structures with unprecedented resolution. Here we report the results of the first tomographic study of the Pyrenees relying on this rich data set. The important aspects of our tomographic study are the precision of both absolute and relative traveltime measurements obtained by a nonlinear simulated annealing waveform fit and the detailed crustal model that has been constructed to compute accurate crustal corrections. Beneath the Massif Central, the most prominent feature is a widespread slow anomaly that reflects a strong thermal anomaly resulting from the thinning of the lithosphere and upwelling of the asthenosphere. Our tomographic images clearly exclude scenarios involving subduction of oceanic lithosphere beneath the Pyrenees. In contrast, they reveal the segmentation of lithospheric structures, mainly by two major lithospheric faults, the Toulouse fault in the central Pyrenees and the Pamplona fault in the western Pyrenees. These inherited Hercynian faults were reactivated during the Cretaceous rifting of the Aquitaine and Iberian margins and during the Cenozoic Alpine convergence. Therefore, the Pyrenees can be seen as resulting from the tectonic inversion of a segmented continental rift that was buried by subduction beneath the European plate., The PYROPE experiment was supported by the French Research Agency ÔANR blancÕ program (project PYROPE, ANR-09-BLAN-0229). We also acknowledge SISMOB, the French seismic mobile pool (a component of the RESIF consortium), for providing us with the seismological instrumentation for the temporary deployments. We thank also thank the IGN and IGC for making their broadband data available to us, Julie Perrot for sending us data from a short period array in Vendee and Jean Michel Douchain for preparing ©2014 American Geophysical Union. All rights reserved. the data of the ReNass stations in the Massif Central. This is a contribution of the Team Consolider-Ingenio 2010 TOPO-IBERIA (CSD2006-00041).

During the Cenozoic, the geodynamics of the western Mediterranean domain has been characterized by a complex history of subduction of Mesozoic oceanic lithosphere. The final stage of these processes is proposed to have led to the development of the Calabria and Gibraltar arcs, whose formation is still under debate. In this study, we take advantage of the dense broad-band station networks now available in the Alborán Sea region, to develop a high-resolution 3-D tomographic P velocity model of the upper mantle beneath the African/Iberian collision zone that will better constraint the past dynamics of this zone. The model is based on 13200 teleseismic arrival times recorded between 2008 and 2012 at 279 stations for which cross-correlation delays are measured with a new technique in different frequency bands centred between 0.03 and 1.0 Hz, and for the first time interpreted using multiple frequency tomography. Our model shows, beneath the Alborán Sea, a strong (4 per cent) fast vertically dipping anomaly observed to at least 650 km depth. The arched shape of this anomaly, and its extent at depth, are coherent with a lithospheric slab, thus favouring the hypothesis of a westward consumption of the Ligurian ocean slab by roll-back during Cenozoic. In addition to this fast anomaly in the deep upper mantle, high intensity slow anomalies are widespread in the lithosphere and asthenosphere beneath Morocco and southern Spain. These anomalies are correlated at the surface with the position of the Rif and Atlas orogens and with Cenozoic volcanic fields. We thus confirm the presence, beneath Morocco, of an anomalous (hot?) upper mantle, but without clear indication for a lateral spreading of the Canary plume to the east., The Morocco M¨unster project was funded under grant DFG TH1530/5-1. The deployment and data processing for Spanish stations was funded by Consolider-Ingenio 2010 project TOPOIBERIA (CSD2006-00041) as well as ALERT-ES (CGL2010- 19803-C03-02). This research is supported by the European Research Council (Advanced grant 226837). The figures were produced using the Generic Mapping Tools (GMT) software (Wessel & Smith 1998; Wessel et al. 2013).

The crustal structure and topography of the Moho boundary beneath the Atlas Mountains of Morocco has been constrained by a controlled source, wide-angle seismic reflection transect: the SIMA experiment. This paper presents the first results of this project, consisting of an almost 700 km long, high-resolution seismic profile acquired from the Sahara craton across the High and the Middle Atlas and the Rif Mountains. The interpretation of this seismic data set is based on forward modeling by raytracing, and has resulted in a detailed crustal structure and velocity model for the Atlas Mountains. Results indicate that the High Atlas features a moderate crustal thickness, with the Moho located at a minimum depth of 35 km to the S and at around 31 km to the N, in the Middle Atlas. Upper crustal shortening is resolved at depth through a crustal root where the Saharan crust underthrusts the northern Moroccan crust. This feature defines a lower crust imbrication that, locally, places the Moho boundary at 40-41 km depth in the northern part of the High Atlas. The P-wave velocity model is characterized by relatively low velocities, mostly in the lower crust and upper mantle, when compared to other active orogens and continental regions. These low deep crustal velocities together with other geophysical observables such as conductivity estimates derived from MT measurements, moderate Bouguer gravity anomaly, high heat flow, and surface exposures of recent alkaline volcanism lead to a model where partial melts are currently emplaced at deep crustal levels and in the upper mantle. The resulting model supports the existence of a mantle upwelling as mechanism that would contribute significantly to sustain the High Atlas topography. However, the detailed Moho geometry deduced in this work should lead to a revision of the exact geometry and position of this mantle feature and will require new modeling efforts, This work has been primarily funded by the Spanish MEC project CGL2007–63889. Additional funding was provided by projects CGL2010–15416, CSD2006-00041, and GL2009–09727 (Spain), CGL2008–03474-E, 07-TOPO_EUROPE_FP-006 (ESF Eurocores) and EAR-0808939 (US, NSF).

We investigate the upper-mantle transition zone thickness beneath the Ibero-Maghrebian region using teleseismic events recorded at 258 seismic stations from the IberArray of the Spanish TopoIberia project. For this purpose, the 410. km and 660. km depth discontinuities are mapped through the detection of P-to- s conversions. In order to add consistency and robustness to the detections, the final results are based on a joint analysis of receiver functions and two different cross-correlation functionals. Discontinuity depths are determined using time corrections obtained from a 3-D velocity model. This study presents the first high-resolution topography maps for the 410 and 660 discontinuities, which show lateral variations in the transition zone thickness beneath the study area. The results are discussed to add new constraints on temperature and composition to seismic velocity anomalies observed in the transition zone beneath the controversial Ibero-Maghrebian region. We obtained a thickened transition zone beneath the Alboran Sea and the north Balearic Sea suggesting low transition zone temperatures, and coinciding with the position of the high-velocity anomalies in the tomographic images related to the Betic-Alboran slab and the Alpine-Tethys remnant slab, respectively. A dominantly thinned transition zone beneath the Gulf of Cadiz and its surroundings suggest high-mantle temperatures. We also found evidences of the presence of a low-velocity layer atop the 410 discontinuity beneath the study area., The IberArray broadband seismic network is part of TOPO-IBERIA (http://www.igme.es/internet/TopoIberia/default.html ). This article is a contribution of the projects CONSOLIDER TOPO-IBERIA [CSD2006-00041], TOPOMED [CGL2008-03474-E/BTE], Rifsis [CGL2009-09727], CGL2012-31472 and P09-RNM-5100.

The different geodynamic models proposed since the late 1990s to account for the complex evolution of the Gibraltar Arc System lack definite constraints on the crustal structure of the Rif orogen. Here we present the first well-resolved P-wave velocity crustal models of the Rif Cordillera and its southern continuation toward the Atlas made using controlled-source seismic data. Two 3001 km-long wide-angle reflection profiles crossed the Rif along NS and EW trends. The profiles recorded simultaneously five land explosions of 1Tn each using 850 high frequency seismometers. The crustal structure revealed from 2-D forward modeling delineates a complex, laterally varying crustal structure below the Rif domains. The most surprising feature, seen on both profiles, is a 50 km deep crustal root localized beneath the External Rif. To the east, the crust thins rapidly by 20 km across the Nekkor fault, indicating that the fault is a crustal scale feature. On the NS profile the crust thins more gradually to 40 km thickness beneath Middle Atlas and 42 km beneath the Betics. These new seismic results are in overall agreement with regional trends of Bouguer gravity and are consistent with recent receiver function estimates of crustal thickness. The complex crustal structure of the Rif orogen in the Gibraltar Arc is a consequence of the Miocene collision between the Iberian and African plates. Both the abrupt change in crustal thickness at the Nekkor fault and the unexpectedly deep Rif crustal root can be attributed to interaction of the subducting Alboran slab with the North African passive margin at late Oligocene-early Miocene times., This research was funded by Spanish RIFSIS project CGL2009–09727. AG benefited from a PhD grant associated to this project. Support was provided by Spanish projects CSD2006-00041 ‘‘Topo-Iberia’’ and CGL2008–03474 ‘‘Topo-Med,’’ as well as the NSF Continental Dynamics Program Grant EAR0808939.

The Canfranc underground laboratory (LSC), excavated under the Central Pyrenees, is mainly devoted to the study of phenomena which needs “cosmic silence.” It also hosts a geodynamical facility, named Geodyn, which holds an accelerometer, a broadband seismometer, and two high-resolution laser strainmeters. During the routine processing of the seismic data, we detected an unusual spectral signature in the 2–10 Hz frequency band, which does not correspond to the typical sources of seismic noise and which can also be recognized in the strain records. After checking against meteorological and hydrological data, we can relate those signals to variations in the discharge by the Aragon River, an Alpine-style river in the southern Pyrenees, located about 400 m from the LSC Geodyn facility. Four main episodes have been identified since early 2011, each lasting 1–2 to 6–8 days. Additionally, a limited number of shorter episodes have also been detected. Three types of river-generated seismic events have been identified, related respectively to moderate rainfall, snowmelt, and flooding events associated to severe storms. Each of those types has distinctive characteristics which allow monitoring the hydrological events from the analysis of seismic and deformation data. A few previous studies have already described the seismic noise close to rivers with larger discharge or in small-scale experimental settings, and we are showing here that the so-called “fluvial seismology” can be useful to study the hydrological evolution of Alpine style streams and may have a potential interest for the civil authorities in charge of the management of hydrological basins.

The results of the MCS LISA seismic survey in the Mediterranean Sea and the wide angle data recorded by the onland stations during this experiment are merged and compared with the ray tracing modeling and the deep structure known from previous refraction studies. The results are very good, arriving at a new deep seismic image of the crustal structure. The LISA seismic profile 26, shown is this publication, crosses in strike line a deep basin close to the eastern Pyrenees. The shallow part of the seismic profile is poorly imaged but, thanks to the very good ELF seismic profiles crossing the LISA survey, the acoustic basement and a decollement level can be drawn. The deep part of the LISA profile data has a much better quality than the shallow part and reveals a high velocity (7.1 km/s) lower crust, overlying a shallow Moho interpreted at 8 s TWTT. The wide angle reflections enable the comparison between the ray tracing measured by distance and the seismic image measured by time thereby making the relationship between the continent and the continental shelf clearly delineated for the first time. The thinning of the thickened crust of the eastern Pyrenees does not occur at the shore but inland at the western boundary of the Roussillon basin. However, the central part of the Gulf of Lion continental shelf forms a deep basin that overlies a thinned crust. The age of the thinning is discussed in the general context of the convergence and divergence of the European and Iberian plates including the Sardinia-Corsica block. The geometry of the transfer faults is studied and shown as not steep and to have normal and strike-slip components. © 2001 Elsevier Science Ltd. All rights reserved.

Inversion for the three-dimensional velocity structure of Mount Etna is performed with a data set of arrival times of P and S waves of local earthquakes from temporary dense arrays of three-component seismographs. A high-Vp body revealed by the original tomography without nearby stations is confirmed, and its image is sharpened using new velocity constraints provided by refraction data. Synthetic tests of Vp and Vp/Vs and comparison with an independent artificial source tomography with a fundamentally different geometry consistently calibrate the significance threshold of the resolution indicators. The trustworthy part of the image shows a high-Vp body centered under the southern part of Valle del Bove above the 6 km below sea level deep basement, which extends towards sea level and may be rooted in or through the crust. It has a large contrast of over 1 km/s with the surrounding sediments and sharp lateral limits and can thus be regarded as made of intrusive material of magmatic origin. The massive high-Vp body is heterogeneous in Vp/Vs. The regions inside it where Vs is relatively low can then be suspected of containing a proportion of melt or be fractured and act as pressure links or transport zones. Such features may be structurally linked and appear to be activated in eruptive phenomena. By taking into account the heterogeneities in structure and physical state retrieved by seismic tomography a succession of seismic events, deformational episodes, and geochemical variation in lavas can be discussed with respect to the well-observed eruptions. Copyright 2000 by the American Geophysical Union., This research is part of the multimethod seismic approach of Etna funded partly by EC Environment Programme, Volcanic Hazard, under contract ETNASEIS EV5V-CJ92-0187 to A. Hirn, R. Nicolich, J. Gallart, and B. Brandsdotti

A crustal tomographic image, from the surface down to 35 km depth beneath the Betic Cordillera (southern Spain), is obtained using data on local earthquakes recorded at stations from the National and Andalusian Seismic Networks. The velocity structure and the hypocentre locations are derived from the inversion of P first arrival times, using an iterative simultaneous inversion method. The reliability of the results is assessed using different control parameters. The inverted velocity field in the uppermost layers shows a significant lateral variability which reflects most of the large-scale geological features of the Betic Cordillera. Well determined local surface anomalies allow to constrain the location and geometry of the most prominent Neogene sedimentary basins. The upper crust is well resolved throughout the whole region, and is characterized by relatively high velocities in the Internal Betics and in the South Iberian Massif and lower velocities within the External Betics. A relatively well constrained event cluster displays a NNE-SSW trend, and outlines the contact zone between the Internal and the External domains. The middle and lower crustal levels show reliable results beneath the central part of the Betic Cordillera. High averaged velocities are obtained within the South Iberian and the Alboran domains, in contrast to a relatively low velocity anomaly which characterizes the boundary between them. These findings support the hypothesis of the lack of well differentiated crustal levels below the contact zone, while crustal layering is better defined beneath the Alboran and the Iberian domains.

The crustal structure of the transition from the NE Iberian Peninsula to the western Mediterranean is characterized by large-scale variations related to its successive compressional and extensional Cenozoic tectonics. The Spanish ESCI (Spanish acronym for seismic studies of the Iberian crust) Program recorded 450 km of deep vertical reflection profiles on land and at sea, to complete a first crustal transect from the Pyrenees to the South Balearic basin. Highly energetic, north dipping reflections imaged by combining the Etude Continentale et Océanique par Reflexion et Refraction Sismique (ECORS) and ESCI land profiles mark a crustal thickening toward the Pyrenees. The reflective band becomes horizontal beneath the Catalan coastal ranges, and the Moho is found at 11s. No evidence of crustal thinning affecting the Iberian mainland is observed. The transition to the Mediterranean basin is constrained by complementary onshore-offshore recordings. Forward modeling combined with multichannel processing of the wide-angle data set shows that a strong thinning of the continental crust by a factor of 2 over a distance of 50 km affects both the Catalan and Balearic flanks of the Valencia trough. This thinning affects mainly the deep crust, characterized by low velocities of 6.4-6.5 km/s, suggesting a removal of part of the lower crust during the rifting processes. Velocities of 7.8-7.9 km/s are interpreted in the uppermost mantle with no evidence of underplating. The Moho appears as a marked discontinuity throughout the transect. The NW part of the Balearic promontory is characterized by a thick and reflective crust from 12 to 30 km depth. An intensely fracturated evaporitic sequence is seen for 100 km along the south Balearic basin. The seismic images of the continent-ocean transition are disturbed by these prominent sediments. However, the deep reflectivity suggests a crustal thinning (Moho at 6-7 s) to be related to the Middle Miocene-present extensional tectonics., This work has been financedb y CICYT projectsG EO89-0858 and GEO90-0733.

An offshore vertical incidence reflection seismic study with simultaneous on-land wide-angle recording has been conducted, as part of the Estudio Sísmico de la Corteza Ibérica Norte (ESCIN) Project, in the NW Iberian Variscan Belt, an area deeply affected by Variscan and Alpine deformation episodes. Line ESCIN-3.3 was recorded across strike of the main Variscan structures, transecting two of the zones in which the NW Iberian Massif has been subdivided. This study intends to correlate the seismic features observed in the near-vertical reflection profile with the velocity model deduced from the wide-angle data, with the well-known geological structure of the Variscan upper crust, and with some other geophysical features described on the basis of offshore and onshore experiments carried out in the area. The main results can be summarized as follows: (1) identification of two important sedimentary basins in the shallow part of the marine seismic section, related with the Mesozoic extension that gave rise to the opening of the Bay of Biscay, (2) correlation of a number of subhorizontal and west dipping intermediate depth reflections with Variscan compressional structures, (3) interpretation of a local set of strong reflections at 6 s (two-way travel time) as lower crust emplaced at an anomalous shallow level (thought to image the northward prolongation of a body with high P wave velocity and high magnetic susceptibility, described on land underneath a late Variscan antiformal structure, the Lugo Dome), and (4) recognition of two controversial highly reflective subhorizontal bands, located at 7-9 and 11-12 s, respectively. The shallowest of them appears to have a lower crustal P wave velocity and to be separated from the deepest one, probably with similar characteristics, by mantle P wave velocity material. On this basis, a duplication of the lower continental crust is inferred. The deepest of the bands could either represent the remnants of a late Paleozoic crustal root or an Alpine underthrusting of the lower continental crust.

This work focuses on the analysis of a unique set of seismological data recorded by two temporary networks of seismometers deployed onshore and offshore in the Central Lesser Antilles Island Arc from Martinique to Guadeloupe islands. During the whole recording period, extending from January to the end of August 2007, more than 1300 local seismic events were detected in this area. A subset of 769 earthquakes was located precisely by using HypoEllipse. We also computed focal mechanisms using P-wave polarities of the best azimuthally constrained earthquakes.We detected earthquakes beneath the Caribbean forearc and in the Atlantic oceanic plate as well. At depth seismicity delineates the Wadati-Benioff Zone down to 170. km depth.The main seismic activity is concentrated in the lower crust and in the mantle wedge, close to the island arc beneath an inner forearc domain in comparison to an outer forearc domain where little seismicity is observed. We propose that the difference of the seismicity beneath the inner and the outer forearc is related to a difference of crustal structure between the inner forearc interpreted as a dense, thick and rigid crustal block and the lighter and more flexible outer forearc. Seismicity is enhanced beneath the inner forearc because it likely increases the vertical stress applied to the subducting plate. © 2011 Elsevier B.V., This work has been carried out with the support of the European Union “Thales Was Right” (UE-FP6-2004-NEST-C-1), the French ANR project “Subsismanti” and also partly by the OBSISMER programme for earthquake monitoring. Spanish Consolider-Ingenio 2010 Topoiberia (CSD2006-00041) now supports one of us (MR).

International audience; In 2007 the Sismantilles II experiment was conducted to constrain structure and seismicity in the central Lesser Antilles subduction zone. The seismic refraction data recorded by a network of 27 OBSs over an area of 65 km × 95 km provide new insights on the crustal structure of the forearc offshore Martinique and Dominica islands. The tomographic inversion of first arrival travel times provides a 3D P-wave velocity model down to 15 km. Basement velocity gradients depict that the forearc is made up of two distinct units: A high velocity gradient domain named the inner forearc in comparison to a lower velocity gradient domain located further trenchward named the outer forearc. Whereas the inner forearc appears as a rigid block uplifted and possibly tilted as a whole to the south, short wavelength deformations of the outer forearc basement are observed, beneath a 3 to 6 km thick sedimentary pile, in relation with the subduction of the Tiburon Ridge and associated seafloor reliefs. North, offshore Dominica Island, the outer forearc is 70 km wide. It extends as far as 180 km to the east of the volcanic front where it acts as a backstop on which the accretionary wedge developed. Its width decreases strongly to the south to terminate offshore Martinique where the inner forearc acts as the backstop. The inner forearc is likely the extension at depth of the Mesozoic magmatic crust outcropping to the north in La Désirade Island and along the scarp of the Karukera Spur. The outer forearc could be either the eastern prolongation of the inner forearc, but the crust was thinned and fractured during the past tectonic history of the area or by recent subduction processes, or an oceanic terrane more recently accreted to the island arc.

This work is funded by the PICASSO project (NSF grant EAR-0808939), The deployment and data processing for Spanish stations was funded by Consolider-Ingenio 2010 project TOPO-IBERIA (CSD2006-00041) as well as ALERT-ES (CGL2010-19803-C03-02).

In the last 10-15 years, the number of high quality seismic stations monitoring the Euro- Mediterranean region has increased significantly, allowing a corresponding improvement in structural constraints. We present here new images of the seismic velocity and anisotropy variations in the uppermost mantle beneath this complex area, compiled from inversion of Pn and Sn phases sampling the whole region. The method of Hearn has been applied to the traveltime arrivals of the International Seismological Center catalogue for the time period 1990-2010. A total of 579 753 Pn arrivals coming from 12 377 events recorded at 1 408 stations with epicentral distances between 220 km and 1 400 km have been retained after applying standard quality criteria (maximum depth, minimum number of recordings, maximum residual values...). Our results show significant features well correlated with surface geology and evidence the heterogeneous character of the Euro-Mediterranean lithosphere. The station terms reflect the existence of marked variations in crustal thickness, consistent with available Moho depths inferred from active seismic experiments. The highest Pn velocities are observed along a continuous band from the Po Basin to the northern Ionian Sea. Other high velocity zones include the Ligurian Basin, the Valencia Trough, the southern Alboran Sea and central part of the Algerian margin. Most significant low-velocity values are associated to orogenic belts (Betics, Pyrenees, Alps, Apennines and Calabrian Arc, Dinarides-Hellenides), and lowvelocity zones are also identified beneath Sardinia and the Balearic Islands. The introduction of an anisotropic term enhances significantly the lateral continuity of the anomalies, in particular in the most active tectonic areas. Pn anisotropy shows consistent orientations subparallel to major orogenic structures, such as Betics, Apennines, Calabrian Arc and Alps. The Sn tomographic image has lower resolution but confirms independently most of the features evidenced in the Pn tomography ©The Authors 2012., This work has been supported by Spanish projects TOPO-IBERIA [CSD2006-00041] and RIFSIS [CGL2009-09727]. A. Gil benefited from a FPI Spanish PhD grant.

In this study, we analyse the 410-km and 660-km upper-mantle transition zone discontinuitiesas seen from seismic P-to-s wave conversions beneath the Eurasian-African Plate boundaryat south Spain and north Morocco. For this purpose we use teleseismic events recorded at43 broad-band seismic stations deployed mainly by the TopoIberia project. The conversionsfrom the upper-mantle discontinuities arrive in the P-wave coda together with other signalsand are usually identified on stacked receiver functions. We build a new processing approachwhich is leaned on receiver functions and which is based on cross-correlation and stackingtechniques to efficiently detect and extract signals by means of their coherence, slowness, traveltime and polarity. In order to add consistency and robustness to the detections, our finalresults are based on a joint analysis of two different cross-correlation functionals and receiverfunctions. This permits to assess errors and to bridge observation gaps due to the breakdownof any of the techniques inherent to signal and noise characteristics. Finally, discontinuitydepths are determined using time corrections obtained from a 3-D velocity model. We presenttopography maps for the 410-km and 660-km discontinuities which show a thickening of thetransition zone beneath the plate boundary towards Morocco. The transition zone thickness isabout global average beneath south Spain (240-250 km) and is thicker beneath east Morocco(250-275 km). This is mainly due to a deeper 660-km discontinuity, while the topography ofthe 410-km discontinuity is smaller. In the Alboran Sea we find an up to 25 km deflection ofthe 660-km discontinuity which suggests that the Alboran Sea heterogeneity or slab is stillsufficiently cold to depress the post-spinel phase transition. We finally discuss the results inorder to add new constraints on temperature and composition to seismic velocity anomaliesobserved in the transition zone beneath south Spain and north Morocco.© The Authors 2013., This is a contribution of the projects Consolider-Ingenio 2010 TOPOIBERIA [CSD2006-00041], TOPOMED CGL2008-03474-E/BTE], Rifsis [CGL2009-09727], CGL2012-31472 and P09-RNM-5100. L. Bonatto benefits from a Ph.D. JaePredoc (CSIC) grant.

Deep seismic profiles of the ILIHA experiment have provided evidence for the presence of anisotropy in the deeper levels of the lithosphere beneath the Ossa-Morena zone of the Hercynian domain of SW Iberia, allowing estimation of its main characteristics—a N15°E fast P-wave velocity direction and a degree of anisotropy of around 4%. The consistency of these results is tested against an anisotropy analysis using teleseismic shear waves. Data recorded in a dense network of up to 13 digital three-component stations, deployed in the area for about 2 months, are used to study the spatial coherence of wave fields, in particular of shear-wave splitting observations, over an array. Significant small-scale lateral variations are observed in the data, suggesting that care should be taken in using single station results as representative for geodynamical interpretations. In spite of the short duration of the test, a few teleseismic events provide useful data. The analysis of SKS and S phases shows evidence of the presence of anisotropy. The results from the different events depict a rather consistent anisotropic structure, with roughly a NE-SW to east-west fast velocity direction. The anisotropic patterns derived from DSS crossing profiles and shear-wave splitting over the Ossa-Morena zone are compared. Mechanisms classically suggested to be responsible for the origin of the anisotropy, such as past deformations of the lithosphere or relative motion between lithosphere and asthenosphere, are discussed to test their consistency with the geophysical and geological data available in the area.

The 300-km-long north-central segment of the Lesser Antilles subduction zone, including Martinique and Guadeloupe islands has been the target of a specific approach to the seismic structure and activity by a cluster of active and passive offshore–onshore seismic experiments. The top of the subducting plate can be followed under the wide accretionary wedge by multichannel reflection seismics. This reveals the hidden updip limit of the contact of the upper plate crustal backstop onto the slab. Two OBS refraction seismic profiles from the volcanic arc throughout the forearc domain constrain a 26-km-large crustal thickness all along. In the common assumption that the upper plate Moho contact on the slab is a proxy of its downdip limit these new observations imply a three times larger width of the potential interplate seismogenic zone under the marine domain of the Caribbean plate with respect to a regular intra-oceanic subduction zone. Towards larger depth under the mantle corner, the top of the slab imaged from the conversions of teleseismic body-waves and the locations of earthquakes appears with kinks which increase the dip to 10–20° under the forearc domain, and then to 60° from 70 km depth. At 145 km depth under the volcanic arc just north of Martinique, the 2007 M 7.4 earthquake, largest for half a century in the region, allows to document a deep slab deformation consistent with segmentation into slab panels. In relation with this occurrence, an increased seismic activity over the whole depth range provides a new focussed image thanks to the OBS and land deployments. A double-planed dipping slab seismicity is thus now resolved, as originally discovered in Tohoku (NE Japan) and since in other subduction zones. Two other types of seismic activity uniquely observed in Tohoku, are now resolved here: “supraslab” earthquakes with normal-faulting focal mechanisms reliably located in the mantle corner and “deep flat-thrust” earthquakes at 45 km depth on the interplate fault under the Caribbean plate forearc mantle. None such types of seismicity should occur under the paradigm of a regular peridotitic mantle of the upper plate which is expected to be serpentinized by the fluids provided from the dehydrating slab beneath. This process is commonly considered as limiting the downward extent of the interplate coupling. Interpretations are not readily available either for the large crustal thickness of this shallow water marine upper plate, except when remarking its likeness to oceanic plateaus formed above hotspots. The Caribbean Oceanic Plateau of the upper plate has been formed earlier by the material advection from a mantle plume. It could then be underlain by a correspondingly modified, heterogeneous mantle, which may include pyroxenitic material among peridotites. Such heterogeneity in the mantle corner of the present subduction zone may account for the notable peculiarities in seismic structure and activity and impose regions of stick-slip behavior on the interplate among stable-gliding areas., This work has been funded by the European Union FP6 NEST (New and Emerging Science and Technology) — INSIGHT programme, under project “THALES WAS RIGHT” no. 029080, by French National Research Agency (ANR) CATTELL programme, German National Science Foundation DFG and TMR of IFM-GEOMAR as well as INSU-CNRS (missions embarquants), and by CPER Martinique for OBSISMER.