The structure and nature of the crust underlying the Santos Basin‐São Paulo Plateau System (SSPS), in the SE Brazilian margin, are discussed based on five wide‐angle seismic profiles acquired during the Santos Basin (SanBa) experiment in 2011. Velocity models allow us to precisely divide the SSPS in six domains from unthinned continental crust (Domain CC) to normal oceanic crust (Domain OC). A seventh domain (Domain D), a triangular shape region in the SE of the SSPS, is discussed by Klingelhoefer et al. (2014). Beneath the continental shelf, a ~100 km wide necking zone (Domain N) is imaged where the continental crust thins abruptly from ~40 km to less than 15 km. Toward the ocean, most of the SSPS (Domains A and C) shows velocity ranges, velocity gradients, and a Moho interface characteristic of the thinned continental crust. The central domain (Domain B) has, however, a very heterogeneous structure. While its southwestern part still exhibits extremely thinned (7 km) continental crust, its northeastern part depicts a 2–4 km thick upper layer (6.0–6.5 km/s) overlying an anomalous velocity layer (7.0–7.8 km/s) and no evidence of a Moho interface. This structure is interpreted as atypical oceanic crust, exhumed lower crust, or upper continental crust intruded by mafic material, overlying either altered mantle in the first two cases or intruded lower continental crust in the last case. The deep structure and v‐shaped segmentation of the SSPS confirm that an initial episode of rifting occurred there obliquely to the general opening direction of the South Atlantic Central Segment.

Ocean infragravity (IG) waves are low‐frequency waves generated along shorelines by incident seas and swell and with heights of the order of 1 cm in the open ocean. Despite these small amplitudes, they can be of much importance for ice shelf break up and errors in measurements of sea level by future satellite altimeters. A combination of numerical model results and in situ data is used to show that bottom pressure signals in the infragravity frequency band can be dominated by bursts of energy that travel across ocean basins, and can last for several days. Two particularly strong events recorded in 2008 are studied, one in the North‐Pacific and the other in the North‐Atlantic. It is shown that infragravity waves can travel across whole oceans basins with the signal recorded on the western shores often dominated by IG waves coming from the opposite shore of that same ocean basin.

© 2014, Bulletin of the Seismological Society of America. All rights reserved. The West Iberia Lithosphere and Asthenosphere Structure (WILAS) project densely covered Portugal with broadband seismic stations for 2 yrs. Here we provide an overview of the deployment, and we characterize the network ambient noise and its sources. After explaining quality control, which includes the assessment of sensor orientation, we characterize the background noise in the short-period (SP), microseismic, and long-period (LP) bands. We observe daily variations of SP noise associated with anthropogenic activity. Temporary and permanent stations present very similar noise levels at all periods, except at horizontal LPs, where temporary stations record higher noise levels. We find that median noise levels are extremely homogeneous across the network in the microseismic band (3–20 s) but vary widely outside this range. The amplitudes of microseismic noise display a strong seasonal variation. The seasonality is dominated by very-long-period double-frequency microseisms (8 s), probably associated with winter storms. Stacks of ambient noise amplitudes show that some microseismic noise peaks are visible across the whole ground-motion spectrum, from 0.3 to 100 s. Periods of increased microseismic amplitudes generally correlate with ocean conditions offshore of Portugal. Some seismic records display an interesting 12 hr cycle of LP (100-s) noise, which might be related to atmospheric tides. Finally, we use plots of power spectral density versus time to monitor changes in LP instrumental response. The method allows the identification of the exact times at which LP response changes occur, which is required to improve the understanding of this instrumental artifact and to eventually correct data.This research was supported by Fundação para a Ciência e Tecnologia through projects WILAS (PTDC/CTE-GIX/097946/2008), QuakeLoc-PT (PTDC/GEO-FIQ/3522/2012), and SCENE (PTDC/CTE-GIX/103032/2008), and by the European Commission FP7 project NERA (Network of European Research Infrastructures for Earthquake Risk Assessment and Mitigation, GA-262330). This is a contribution to PEST-OE/CTE/LA0019/2011 (IDL). The first author acknowledges a Marie Curie International Reintegration Grant from the European Commission, FP7 (PIRG03-GA-2008-230922)Peer Reviewe

Independent models ofPwave andSwave velocity anomalies in the mantle derived from seismic tomography help to distinguish thermal signatures from those of partial melt, volatiles, and compositional variations. Here we use seismic data from SW Europe and NW Africa, spanning the region between the Pyrenees and the Canaries, in order to obtain a newS‐SKSrelative arrival‐time tomographic model of the upper mantle below Iberia, Western Morocco, and the Canaries. Similar to previousPwave tomographic results, theSwave model provides evidence for (1) subvertical upper‐mantle low‐velocity structures below the Canaries, Atlas Ranges, and Gibraltar Arc, which are interpreted as mantle upwellings fed by a common lower‐mantle source below the Canaries; and (2) two low‐velocity anomalies below the eastern Rif and Betics that we interpret as the result of the interaction between quasi‐toroidal mantle flow induced by the Gibraltar slab and the mantle upwelling behind it. The analysis of teleseismicPwave andSwave arrival‐time residuals and the conversion of the low‐velocity anomalies to temperature variations suggest that the upwellings in the upper mantle below the Canaries, Atlas Ranges, and Gibraltar Arc system may be solely thermal in nature, with temperature excesses in the range ~100–350 °C. Our results also indicate that local partial melting can be present at lithospheric depths, especially below the Atlas Ranges. The locations of thermal mantle upwellings are in good agreement with those of thinned lithosphere, moderate to high heat‐flow measurements, and recent magmatic activity at the surface.