Description: Highlights • Along-strike variations of tectonic framework in northeastern Caribbean margin are studied. • Shallow plate boundary structure related to the slab geometry has been defined. • First-order fault systems and its associated features have been mapped along the margin. Abstract The North American (NOAM) plate converges with the Caribbean (CARIB) plate at a rate of 20.0 ± 0.4 mm/yr. towards 254 ± 1°. Plate convergence is highly oblique (20–10°), resulting in a complex crustal boundary with along-strike segmentation, strain partitioning and microplate tectonics. We study the oblique convergence of the NOAM and CARIB plates between southeastern Cuba to northern Puerto Rico using new swath multibeam bathymetry data and 2D multi-channel seismic profiles. The combined interpretation of marine geophysical data with the seismicity and geodetic data from public databases allow us to perform a regional scale analysis of the shallower structure, the seismotectonics and the slab geometry along the plate boundary. Due to differential rollback between the NOAM oceanic crust north of Puerto Rico and the relative thicker Bahamas Carbonate Province crust north of Hispaniola a slab tear is created at 68.5°W. The northern margin of Puerto Rico records the oblique high-dip subduction and rollback of the NOAM plate below the island arc. Those processes have resulted in a forearc transpressive tectonics (without strain partitioning), controlled by the Septentrional-Oriente Fault Zone (SOFZ) and the Bunce Fault Zone (BFZ). Meanwhile, in the northern margin of Hispaniola, the collision of the Bahamas Carbonate Province results in high plate coupling with strain partitioning: SOFZ and Northern Hispaniola Deformed Belt (NHDB). In the northern Haitian margin, compression is still relevant since seismicity is mostly associated with the deformation front, whereas strike slip earthquakes are hardly anecdotal. Although in Hispaniola intermediate-depth seismicity should disappear, diffuse intermediate-depth hypocenter remains evidencing the presence of remnant NOAM subducted slab below central and western Hispaniola. Results of this study improve our understanding of the active tectonics in the NE Caribbean that it is the base for future assessment studies on seismic and tsunamigenic hazard.

Description: Highlights • We present the first unified stratigraphy of the westernmost Mediterranean. • Miocene marine basins currently onshore are integrated. • We present a kinematic model for the Alboran and Algero-Balearic basins. • We evaluate western Mediterranean geodynamic models in the framework of basin evolution. Abstract Based on more than 4500 km of new and re-processed multichannel seismic lines, high-resolution seafloor bathymetry, available well data, and basement dredge samples, we have re-evaluated the entire stratigraphy and the tectonic evolution of the Alboran and western Algerian basins. We have correlated the sediment units deposited since the beginning of the formation of the different sub-basins, and we present for the first time a coherent stratigraphy and large-scale tectonic evolution of the whole region. The results provide the information to test and refine models of the geodynamic evolution of the westernmost Mediterranean. The data analysis supports an independent evolution of the sub-basins through the latemost Oligocene and Miocene, and a common Plio-Holocene evolution. The latemost Oligocene and Miocene evolution was controlled by the evolution of the Gibraltar subduction system. The oldest sedimentary unit is restricted to the West Alboran and Malaga basins depocenter that during the latemost Oligocene and early Miocene connected to some smaller marine basins currently uplifted and located onshore on the Betics range. Later, during the middle Miocene, the Habibas and Pytheas sub-basins formed a second depocenter on the North African margin. The different sedimentary units found in both depocenters, together with their different deformation patterns, support that the West Alboran-Malaga and the Habibas-Pytheas depocenters were separated by a major tectonic boundary. The early Tortonian initial arc magmatic activity produced the formation of new areas floored by a volcanic basement by the end of the late Tortonian, when the first sedimentary units deposited in the East Alboran sub-basin, and probably during the late Tortonian-early Messinian in the South Alboran sub-basin. Extension of the back-arc setting created oceanic crust flooring the Algero Balearic Basin. The extensional formation of the westernmost Mediterranean basins ended in the latemost Miocene. The western migration of the subduction system stopped and the convergence between the African and the European tectonic plates started to dominate the tectonic evolution of the region. During the Plio-Holocene, the sub-basins did not further subside individually so that these sediments have spread out across the whole Alboran Basin. A new tectonic contractional and strike-slip fault system developed that is active nowadays. The integration of our results together with the most recent tomographic studies has been used to test and refine the existing kinematic models of the area. None of the existing models explains all our large-scale observations.

Description: Highlights • We identify the largest active fault systems of the Alboran Basin. • Characterization of faults is key for accurate tsunamigenic potential estimations. • Alboran largest fault systems may generate Mw 〉 7 earthquakes. • These earthquakes have the potential to generate significant tsunami waves approaching the coast. Abstract The westernmost Mediterranean hosts part of the plate boundary between the European and African tectonic plates. Based on the scattered instrumental seismicity, this boundary has been traditionally interpreted as a wide zone of diffuse deformation. However, recent seismic images and seafloor mapping studies support that most of the plate convergence may be accommodated in a few tectonic structures, rather than in a broad region. Historical earthquakes with magnitudes Mw 〉 6 and historical tsunamis support that the low-to-moderate instrumental seismicity might also have led to underestimation of the seismogenic and tsunamigenic potential of the area. We evaluate the largest active faults of the westernmost Mediterranean: the reverse Alboran Ridge, and the strike-slip Carboneras, Yusuf and Al-Idrissi fault systems. For the first time, we use a dense grid of modern seismic data to characterize the entire dimensions of the main fault systems, accurately describe the geometry of these structures and estimate their seismic source parameters. Tsunami scenarios have been tested based on 3D-surfaces and seismic source parameters, using both uniform and heterogeneous slip distributions. The comparison of our results with previous studies, based on limited information on the fault geometry and kinematics, indicates that accurate fault geometries and heterogeneous slip distributions are needed to properly assess the seismic and tsunamigenic potential in this area. Based on fault scaling relations, the four fault systems have a large seismogenic potential, being able to generate earthquakes with Mw 〉 7. The reverse Alboran Ridge Fault System has the largest tsunamigenic potential, being able to generate a tsunami wave amplitude greater than 3 m in front of the coasts of Southern Spain and Northern Africa.