Perturbation of the sierpinski antenna to allocate the operating bands

A scheme for modifying the spacing between the bands of the Sierpinski antenna is introduced. Experimental results of two novel designs of fractal antennas suggest that the fractal structure can be perturbed to enable the log-period to be changed while still maintaining the multiband behaviour of the antenna.Peer ReviewedPostprint (published version

Configuration of geological domains and geodynamic evolution of the Africa-Eurasia plate boundary off SW Iberia revisited based on seismic velocity and density models

European Geosciences Union General Assembly 2015 (EGU2015), 12-17 April 2015, Vienna, Austria.-- 1 pageWe present a new classification of geological (basement) domains at the Africa-Eurasia plate boundary offshore SW Iberia, together with a regional geodynamic reconstruction spanning from the Mesozoic extension to the Neogene-to-present-day convergence. It is based on seismic velocity and density models along two regional wide- angle seismic transects, one running NW-SE from the Tagus to the Seine abyssal plains, and the other running N-S from S Portugal to the Seine Abyssal Plain, combined with previously available information. The seismic velocity and density structure at the Seine Abyssal Plain and the internal Gulf of Cadiz indicates the presence of a highly heterogeneous oceanic crust, similar to that described in ultra-slow spreading centers, whereas in the Horseshoe and Tagus abyssal plains, the basement structure resembles that of exhumed mantle sections identified in the Northern Atlantic margin. The integration of all this new information allows defining the presence of three oceanic domains off SW Iberia: (1) the Seine Abyssal Plain domain, generated during the first stages of slow seafloor spreading in the NE segment of the Central Atlantic (Early Jurassic); (2) the Gulf of Cadiz domain, made of oceanic crust generated in the Alpine-Tethys spreading system between Iberia and Africa, which was coeval with the formation of the Seine Abyssal Plain domain and lasted up to the North Atlantic continental break-up (Late Jurassic); and (3) the Gorringe Bank domain, mainly made of rocks exhumed from the mantle with little synchronous magmatism, which formed during the first stages of North Atlantic opening (Early Cretaceous). Our models suggest that the Seine Abyssal Plain and Gulf of Cadiz domains are separated by the Lineament South strike-slip fault, whereas the Gulf of Cadiz and Gorringe Bank domains appear to be limited by a deep thrust fault located at the center of the Horseshoe Abyssal Plain, which coincides with the seismicity cluster nucleated in the middle of the plain that shows moment tensor solutions of reverse faulting at depths of 40–60 km. The formation and evolution of these three domains during the Mesozoic is key to understand the sequence of events that occurred during the first stages of opening of the Northern Atlantic and its connection and interplay with the Western Mediterranean basinPeer Reviewe

New deep multichannel seismic reflection images from the Alboran Basin: The TOPOMED-GASSIS dataset

European Geosciences Union General Assembly 2015 (EGU2015), 12-17 April 2015, Vienna, Austria.-- 1 pageThe Alboran Basin (Western Mediterranean) is located between the Iberian Peninsula and Africa. Along this basin runs the diffuse plate boundary between Iberia and Africa. In order to improve the knowledge of the lithospheric structure in this region, the TOPOMED-GASSIS cruise took place during October 2011 on board the RV Sarmiento de Gamboa. During this cruise, the new deep multichannel seismic acquisition system was used for the first time. The equipment used were two high volume G-gun arrays (2000 psi / 2500 psi) and up to 6 km long Sercel multichannel digital streamer (408 / 480 active channels) towed behind the vessel. The results correspond to a series of multichannel seismic profiles with unprecedented quality, which allows us to apply state of the art processing and imaging techniques to obtain the deep tectonic structure of the plate boundary while keeping a good resolution in the sedimentary infill of the basin. A complete processing sequence has been used in order to increase the signal to noise ratio, including deconvolution, multiple attenuation and time migration. A high-quality deep penetration dataset has been acquired using the new instrumentation allowing to image the whole basin at a crustal scale. The results are high-quality sections for interpretation through frequency preservation, effective multiple attenuation and velocity analysis. Moreover, we will carry out Pre-Stack Depth Migration algorithms to selected profiles, in order to obtain the real geometry of the structures at depthPeer Reviewe

The heterogeneous distribution of elastic properties in the tsunamigenic region of subduction zones

European Geosciences Union (EGU) General Assembly 2020, 4-8 May 2020In the shallow region of subduction zones, topographic variations of the interplate interface condition the structural integrity of the upper plate, and thus the distribution of elastic properties in this region, which determines its tsunamigenic potential. Yet, we know little about the distribution of elastic properties in these shallow regions, which yields large uncertainty during tsunami hazard assessment. Here we assess topographic variations of the interplate boundary as well as the distribution of elastic properties of the upper plate in two tsunamigenic regions of the Middle American Trench. We focus on the rupture area of three tsunami earthquakes, the 1992 Nicaragua event, and the 1932 and 1995 Jalisco-Colima earthquakes (Pacific Mexican coast). We use 2D coincident wide-angle (WAS) and multichannel seismic (MCS) lines acquired across the rupture area of each event to jointly invert refracted and reflected travel-times (TT) and obtain the P-wave velocity (Vp) structure of the tsunamigenic region of the upper plate, and the geometry of the interplate boundary. Mixing both types of seismic data allowed for the first time to retrieve small-scale local topographic variations of the interplate that would have been omitted with the classical inversion of WAS TT. From Vp, we derive other elastic parameters namely, density, S-wave velocity, and rigidity using well-established empirical relationships. The results show that the heterogeneous distribution of the elastic properties of the upper plate in the shallow tsunamigenic region correlates with topographic variations of the interplate in both margins. These results not only sustain the direct relationship between the interplate relief and the tectonic structure of the overriding plate as it has been already stated by previous authors, but they also allow to quantify the relationship between topographic highs of the subducted plate with low rigidity regions in the upper plate. This quantification is of paramount importance in these shallow regions of the subduction, because low rigidity implies high slip during coseismic deformation, and therefore, high tsunamigenic potential. The heterogeneous distribution of elastic properties inferred for the upper plate in this study should be considered during tsunami modeling, tsunami hazard assessment and tsunami early warning system

The continent-to-ocean transition in the Iberia Abyssal Plain

Conceptual models of magma-poor rifting are strongly based on studies of the nature of the basement in the continent-to-ocean transition of the Iberia Abyssal Plain, and suggest that exhumed mantle abuts extended continental crust. Yet, basement has only been sampled at a few sites, and its regional nature and the transition to seafloor spreading inferred from relatively low-resolution geophysical data are inadequately constrained. This uncertainty has led to a debate about the subcontinental or seafloor-spreading origin of exhumed mantle and the rift-related or oceanic nature of magmatic crust causing the magnetic J anomaly. Different interpretations change the locus of break-up by >100 km and lead to debate of the causative processes. We present the tomographic velocity structure along a 360-km-long seismic profile centered at the J anomaly in the Iberia Abyssal Plain. Rather than delineating an excessive outpouring of magma, the J anomaly occurs over subdued basement. Furthermore, its thin crust shows the characteristic layering of oceanic crust and is juxtaposed to exhumed mantle, marking the onset of magma-starved seafloor spreading, which yields the westward limit of an ~160-km-wide continent–ocean transition zone where continental mantle has been unroofed. This zone is profoundly asymmetric with respect to its conjugate margin, suggesting that the majority of mantle exhumation occurs off Iberia. Because the J anomaly is related to the final break-up and emplacement of oceanic crust, it neither represents synrift magmatism nor defines an isochron, and hence it poorly constrains plate tectonic reconstructions

Differential clinical characteristics and prognosis of intraventricular conduction defects in patients with chronic heart failure

Intraventricular conduction defects (IVCDs) can impair prognosis of heart failure (HF), but their specific impact is not well established. This study aimed to analyse the clinical profile and outcomes of HF patients with LBBB, right bundle branch block (RBBB), left anterior fascicular block (LAFB), and no IVCDs. Clinical variables and outcomes after a median follow-up of 21 months were analysed in 1762 patients with chronic HF and LBBB (n = 532), RBBB (n = 134), LAFB (n = 154), and no IVCDs (n = 942). LBBB was associated with more marked LV dilation, depressed LVEF, and mitral valve regurgitation. Patients with RBBB presented overt signs of congestive HF and depressed right ventricular motion. The LAFB group presented intermediate clinical characteristics, and patients with no IVCDs were more often women with less enlarged left ventricles and less depressed LVEF. Death occurred in 332 patients (interannual mortality = 10.8%): cardiovascular in 257, extravascular in 61, and of unknown origin in 14 patients. Cardiac death occurred in 230 (pump failure in 171 and sudden death in 59). An adjusted Cox model showed higher risk of cardiac death and pump failure death in the LBBB and RBBB than in the LAFB and the no IVCD groups. LBBB and RBBB are associated with different clinical profiles and both are independent predictors of increased risk of cardiac death in patients with HF. A more favourable prognosis was observed in patients with LAFB and in those free of IVCDs. Further research in HF patients with RBBB is warranted

Onshore-Offshore active tectonics along the Carboneras Fault Zone (Eastern Betic Cordilleras)

Primera Reunión Ibérica sobre Fallas Activas y Paleosismología, 27-29 de Octubre de 2010, Sigüenza, Guadalajara, EspañaPeer Reviewe

Estudio de la actividad tectónica reciente de la falla de carboneras tierra-mar (cordilleras béticas)

Inciativa Ibérica para el Estudio de las Fallas Activas (IBERFAULT), Primera Reunión Ibérica sobre Fallas Activas y Paleosismología - Primeira Reunião Ibérica sobre Falhas Activas e Paleossismologia - First Iberian Meeting on Active Faults and Paleoseismology, 27-29 de Octubre de 2010, Sigüenza, Guadalajara, España.-- 3 pages, 1 figureThe onshore-offshore Carboneras Fault Zone (CFZ), located along the Eastern Betics Shear Zone, is described and analyzed with the aim of establishing its seismic potential. Bathymetry and seismic profiles show a large variability of transpressive structures along the fault zone coinciding with onshore structures. Both onshore and offshore studies show faulted Quaternary layers and mass movement deposits related to paleoearthquakes suggesting that the CFZ is seismogenic. Analysis of the onshore-offshore fault geomorphology and of the paleoearthquake deposits in trenches allows us to obtain some of the paleoseismic parameters. Based on this data, we infer that the CFZ is a slow structure with minimum recurrence periods of 13.5 ka, minimum strike-slip rates of 0.6 mm/a and dip-slip rates between 0.05 mm/a and 0.16 mm/a. Onshore, a faulted and buried paleochannel constrains the last earthquake to AD 772-889. Empirical relationships allow for the estimation of maximum earthquake magnitudes (Mw) of 7.4 for the northern segment, 6.8 for the central segment and 6.2 for the southern segmentThis work has been funded by Spanish national projects IMPULS (REN 2003-05996/MAR), EVENT (CGL2006-12861-C02-01, and -02), and MCYT acciones complementarias “Caracterización del potencial sísmico de la falla de Carboneras mediante trincheras” (CGL2004-20214-E) and “Streamer” (CTM2004-21203-E). It is also supported by the Consolider-Ingenio 2010 programme, CSD 2006-0004 “Topo-Iberia”Peer Reviewe

Perturbation of the sierpinski antenna to allocate the operating bands

A scheme for modifying the spacing between the bands of the Sierpinski antenna is introduced. Experimental results of two novel designs of fractal antennas suggest that the fractal structure can be perturbed to enable the log-period to be changed while still maintaining the multiband behaviour of the antenna.Peer Reviewe