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Probabilistic Tsunami Hazard Assessment requires the existence of a synthetic earthquake catalogue obeying the geodynamic framework of the source area and a fault model for each event. Usually, we assume a constant fault displacement, eventually filtered by a simple closure condition. The distribution of events by magnitude classes follows a truncated Gutenberg-Richter law with epicentres uniformly distributed in the source domain. This approach makes that the slip on the source structures will extend beyond the generation domain being heterogeneous inside that domain. This contradicts the assumption that the slip is caused by geodynamic constraints. Here, we propose a methodology for creating synthetic earthquake catalogues and we apply it to the Gloria Fault in the Atlantic. With three instrumental tsunamis recorded: 08.05.1939, 25.11.1941 and 26.05.1975 [1]. Additionally, we propose a semi-empirical scaling law for the generation of the tsunamigenic earthquakes

In this study we present a 3D P-wave upper-mantle tomography model of the SW Iberian margin and Alboran Sea based on teleseismic arrival times recorded by Iberian and Moroccan land stations and by a seafloor network deployed for 1 year in the Gulf of Cadiz area during the EC-NEAREST project. The 3D model was computed down to 600 km depth. The tomographic images exhibit significant velocity contrasts, as large as 3%, confirming the complex evolution of this plate boundary region. Prominent high-velocity anomalies are found beneath Betics-Alboran Sea, off-shore SW Portugal, and N Portugal, at sublithospheric depths. The transition zones between high and low velocity anomalies in SW and S Iberia are associated to the contact of oceanic and continental lithosphere. The fast structure below the Alboran Sea-Granada area depicts a L-shaped body steeply dipping from the uppermost mantle to the transition zone where it becomes less curved. This anomaly is consistent with the results of previous tomographic investigations and recent geophysical data such as stress distribution, GPS measurements of plate motion, and anisotropy patterns. In the Atlantic domain, under the Horseshoe Abyssal Plain, the main feature is a high-velocity zone found at uppermost mantle depths. This feature appears laterally separated from the positive anomaly recovered in the Alboran domain by the interposition of low-velocity zones which characterize the lithosphere beneath the SW Iberian peninsula margin, suggesting that there is no continuity between the high velocity anomalies of the two domains west and east of the Gibraltar Strait.

The sedimentary structure in the Gulf of Cadiz has been extensively studied by oil exploration companies. However, up to now little is known about its deep crustal structure. Moreover, the total thickness of the sedimentary layers remains unknown in large areas. The purpose of this paper is the crustal-scale interpretation of deep seismic near-vertical reflection and refraction/wide-angle reflection data obtained during the IAM (Iberian Atlantic Margins) project, carried out in 1993. Our results indicate that a continental type crust is underlying the entire Gulf of Cadiz, with progressive thinning from east to west. The sedimentary cover shows a great thickness, reaching 8 km in the center of the Gulf. Three main sedimentary units can be recognized: Jurassic-Cretaceous calcareous rocks, continuation of Algarve outcrops; the Allochthonous Units of Guadalquivir/Gulf of Cadiz, the offshore continuation of the inland Carmona nappe; and sub-horizontal post-Miocene marine sediments. The crystalline crust is divided into three main layers: the upper crust is characterized by P-wave velocity values of 5.7-6.1 km/s: the middle crust shows values of 6.3-6.4 km/s: the lower crust has a mean vertical velocity gradient of 0.02 km/s/km, with velocities between 6.9 to 7.1 km/s. The total crustal thickness varies from 27 km for the eastern part of the studied area, to 20 km for the westernmost part. The crustal thinning is more pronounced in a N-S direction than in an E-W direction. No major structures related with a defined Iberia-Africa plate boundary could be found.

The mode of crustal thinning in the southwestern margin of the Iberian Peninsula is investigated along a transect that extends from onshore Iberia to the eastern end of the Horseshoe Abyssal Plain. On onshore areas, the crustal structure has been deduced using wide-angle seismic reflection data, whereas offshore we have used coincident steep and wide-angle reflection data along a NE-SW oriented seismic profile that extends from Cape San Vicente to the Horseshoe Abyssal Plain. In addition, 2D gravity modelling has been performed to validate the crustal structure deduced from seismic data. Our model results reveal that the crust undergoes a strong but continuous thinning from 31 km onshore Iberia to less than 15 km in the Horseshoe Abyssal Plain and that thinning occurs over horizontal distances of about 120 km.