The SW Iberian margin host the present-day convergent plate boundary between Iberia and Nubia. Regional seismic activity is characterized by low to moderate events, although large historical and instrumental earthquakes (Mw>8.0) have been occurred, such as the 1755 Lisbon and 1969 Horseshoe ones. The NW-SE convergence (4-5 mm/yr) is accommodated by thrusts and a set of strike-slip faults that conforms a 600 km-long and 300 km-wide deformation band named the SWIM Fault Zone. The seismogenic Lineament South (LS), a WNW-ESE 350 km-long dextral strike-slip fault, is the most prominent among them and represents an important tsunami hazard for the SW Iberian coasts due to its extension, orientation and proximity to the coast. In this work we show multi-scale seismic profiles across the LS that reveal the Plio-Quaternary activity of the fault. The LS cuts and displaces the entire sedimentary sequence up to the seafloor, generating a set of continuous crest-and-troughs of hundreds of meters wide over the seafloor. Ultra-high resolution bathymetry acquired with AUV along two 15 km-long segments of the LS shows the presence of pull-apart basins, pressure ridges, semi-circular escarpments interpreted as collapsed structures, sedimentary features such as submarine dunes with lengths ranging from 200 m to 6 km, large longitudinal erosive bed-forms interpreted as furrows, and mass movement scars

International Conference on Seafloor Forms, Processes and Evolution, 4-6 July 2022, Valletta, Malta

Peer reviewed