General Bathymetric Chart of the Oceans (GEBCO) has released the GEBCO_2014 grid, a new digital bathymetric model of the world ocean floor merged with land topography from publicly available digital elevation models. GEBCO_2014 has a grid spacing of 30 arc seconds, and updates the 2010 release (GEBCO_08) by incorporating new versions of regional bathymetric compilations from the International Bathymetric Chart of the Arctic Ocean (IBCAO), the International Bathymetric Chart of the Southern Ocean (IBCSO), the Baltic Sea Bathymetry Database (BSBD), and data from the European Marine Observation and Data network (EMODnet) bathymetry portal, among other data sources. Approximately 33% of ocean grid cells (not area) have been updated in GEBCO_2014 from the previous version, including both new interpolated depth values and added soundings. These updates include large amounts of multibeam data collected using modern equipment and navigation techniques, improving portrayed details of the world ocean floor. Of all non-land grid cells in GEBCO_2014, approximately 18% are based on bathymetric control data, i.e., primarily multibeam and single beam soundings, or pre-prepared grids which may contain some interpolated values. The GEBCO_2014 grid has a mean and median depth of 3897 m and 3441 m, respectively. Hypsometric analysis reveals that 50% of the Earth's surface is comprised of seafloor located 3200 m below mean sea level, and that ~900 ship-years of surveying would be needed to obtain complete multibeam coverage of the world's oceans.

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A new digital bathymetric model of the world's oceans

Global Bathymetry and Topography at 15 Arc Sec: SRTM15+

Tethys–Atlantic interaction along the Iberia–Africa plate boundary: The Betic–Rif orogenic system

The Betic-Rif arc is one of the smallest and tightest orogenic arcs on Earth, and together with its extensional hinterland, the Albor´ an Domain, it formed between two colliding continents. The region provides examples of a range of tectonic processes that are not predictable from the rules of rigid-plate tectonics. The AlborDomain reveals two stages of subduction and accre- tion, with different thermal histories and mechanisms of exhumation. The external Betic-Rif thrust belt illustrates four processes that create an arcuate orogen and a strongly divergent pattern of slip vectors: (a) the interaction between the westward moving Albor´ an Domain and the converging African and Iberian margins, (b) divergence in relative motion due to extension within the Albor´ an Domain, (c) slip partitioning onto strike-slip faults within the arc, and (d ) vertical-axis rotations resulting from oblique convergence on the limbs of the arc.

The Betic-Rif Arc and Its Orogenic Hinterland: A Review

/pdf/evolution-of-the-late-miocene-mediterranean-atlantic-2tsr8oquz4.pdf

Evolution of the Late Miocene Mediterranean–Atlantic gateways and their impact on regional and global environmental change

The quest for the Africa–Eurasia plate boundary west of the Strait of Gibraltar

The missing link in the plate boundary between Eurasia and Africa in the central Atlantic is presented and discussed. A set of almost linear and sub parallel dextral strike–slip faults, the SWIM1 Faults, that form a narrow band of deformation over a length of 600 km coincident with a small circle centred on the pole of rotation of Africa with respect to Eurasia, was mapped using a new swath bathymetry compilation available in the area offshore SW Portugal. These faults connect the Gloria Fault to the Rif–Tell Fault Zone, two segments of the plate boundary between Africa and Eurasia. The SWIM faults cut across the Gulf of Cadiz, in the Atlantic Ocean, where the 1755 Great Lisbon earthquake, M ~ 8.5–8.7, and tsunami were generated, providing a new insight on its source location.

R. Ramella

Papers

The quest for the Africa–Eurasia plate boundary west of the Strait of Gibraltar

The Quest for the Africa-Eurasia plate boundary West of the Strait of Gibraltar