@article {Gutscher2012, title = {{The Gibraltar subduction: A decade of new geophysical data}}, journal = {Tectonophysics}, volume = {574-575}, year = {2012}, month = {oct}, pages = {72{\textendash}91}, abstract = {The Gibraltar arc, spans a complex portion of the Africa-Eurasia plate boundary marked by slow oblique convergence and intermediate and deep focus seismicity. The seemingly contradictory observations of a young extensional marine basin surrounded by an arcuate fold-and-thrust belt, have led to competing geodynamic models (delamination and subduction). Geophysical data acquired in the past decade provide a test for these models and support a narrow east-dipping, subduction zone. Seismic refraction studies indicate oceanic crust below the western Gulf of Cadiz. Tomography of the upper mantle reveals a steep, east-dipping high P-wave velocity body, beneath Gibraltar. The anisotropic mantle fabric from SKS splitting shows arc-parallel "fast directions", consistent with toroidal flow around a narrow, westward retreating subducting slab. The accompanying WSW advance of the Rif-Betic mountain belt has constructed a thick pile of deformed sediments, an accretionary wedge, characterized by west-vergent thrust anticlines. Bathymetric swath-mapping images an asymmetric embayment at the deformation front where a 2. km high basement ridge has collided. Subduction has slowed significantly since 5. Ma, but deformation of recent sediments and abundant mud volcanoes suggest ongoing activity in the accretionary wedge. Three possible origins for this deformation are discussed; gravitational spreading, overall NW-SE convergence between Africa and Iberia and finally a WSW tectonic push from slow, but ongoing roll-back subduction. In the absence of arc volcanism and shallow dipping thrust type earthquakes, evidence in favor of present-day subduction can only be indirect and remains the object of debate. Continued activity of the subduction offers a possible explanation for great (M. >. 8.5) earthquakes known to affect the area, like the famous 1755 Great Lisbon earthquake. Recent GPS studies show SW motion of stations in N Morocco at velocities of 3-6. mm/yr indicating the presence of an independent block, a "Rif-Betic-Alboran" microplate, situated between Iberia and Africa. {\textcopyright} 2012 Elsevier B.V.}, keywords = {Accretionary wedge, Active deformation, earthquakes, Iberia, Roll-back subduction, Tethys oceanic lithosphere}, issn = {00401951}, doi = {10.1016/j.tecto.2012.08.038}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-84867273669\&partnerID=tZOtx3y1}, author = {Gutscher, M.-A. and Dominguez, S. and Westbrook, G.K. and Le Roy, P. and Rosas, F. and Duarte, J.C. and Terrinha, P. and Miranda, J.M. and Graindorge, D. and Gailler, A. and Sallar{\`e}s, V. and Bartolome, R.} } @article {Geissler2010, title = {{Focal mechanisms for sub-crustal earthquakes in the Gulf of Cadiz from a dense OBS deployment}}, journal = {Geophysical Research Letters}, volume = {37}, number = {18}, year = {2010}, month = {sep}, pages = {n/a{\textendash}n/a}, abstract = {An eleven-month deployment of 25 ocean bottom seismometers provides an unprecedented opportunity to study low-magnitude local earthquakes in the complex transpressive plate boundary setting of the Gulf of Cadiz, known for the 1755 Lisbon earthquake and tsunami. 36 relocated earthquakes (ML 2.2 to 4.8) concentrate at 40-60 km depth, near the base of the seismogenic layer in \~{}140 Ma old oceanic mantle lithosphere, and roughly align along two perpendicular, NNE-SSW and WNW-ESE striking structures. First motion focal mechanisms indicate compressive stress for the cluster close to the northern Horseshoe fault termination which trends perpendicular to plate convergence. Focal mechanisms for the second cluster near the southern termination of the Horseshoe fault indicate a strike-slip regime, providing evidence for present-day activity of a dextral shear zone proposed to represent the Eurasia-Africa plate contact. We hypothesize that regional tectonics is characterized by slip partitioning. {\textcopyright} 2010 by the American Geophysical Union.}, issn = {00948276}, doi = {10.1029/2010GL044289}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-77957722745\&partnerID=tZOtx3y1}, author = {Geissler, W. H. and Matias, L. and Stich, D. and Carrilho, F. and Jokat, W. and Monna, S. and IbenBrahim, A. and Mancilla, F. and Gutscher, M.-A. and Sallar{\`e}s, V. and Zitellini, N.} }