Sensitivity of Tsunami Scenarios to Complex Fault Geometry and Heterogeneous Slip Distribution: Case‐Studies for SW Iberia and NW Morocco

The SW Iberian margin is one of the most seismogenic and tsunamigenic areas in W‐Europe, where large historical and instrumental destructive events occurred. To evaluate the sensitivity of the tsunami impact on the coast of SW Iberia and NW Morocco to the fault geometry and slip distribution for local earthquakes, we carried out a set of tsunami simulations considering some of the main known active crustal faults in the region: the Gorringe Bank (GBF), Marquês de Pombal (MPF), Horseshoe (HF), North Coral Patch (NCPF) and South Coral Patch (SCPF) thrust faults, and the Lineament South strike‐slip fault. We started by considering for all of them relatively simple planar faults featuring with uniform slip distribution; we then used a more complex 3D fault geometry for the faults constrained with a large 2D multichannel seismic dataset (MPF, HF, NCPF, and SCPF); and finally, we used various heterogeneous slip distributions for the HF. Our results show that using more complex 3D fault geometries and slip distributions, the peak wave height at the coastline can double compared to simpler tsunami source scenarios from planar fault geometries. Existing tsunami hazard models in the region use homogeneous slip distributions on planar faults as initial conditions for tsunami simulations and therefore underestimate tsunami hazard. Complex 3D fault geometries and non‐uniform slip distribution should be considered in future tsunami hazard updates. The tsunami simulations also support the finding that submarine canyons attenuate the wave height reaching the coastline, while submarine ridges and shallow shelves have the opposite effect. Plain Language Summary Deformation along the present‐day plate boundary between Africa and Eurasia off SW Iberia is distributed over a 200‐km‐wide and 600‐km‐long area, and is mainly accommodated by thrusts and strike‐slip faults. The region hosts frequent seismic activity of moderate magnitude punctuated by higher magnitude events, which have also originated major historical and pre‐historical tsunamis. The run‐up and coastal area affected by these tsunamis depend on the characteristics and location of the seismic source, bathymetry, and morphology of the coasts. Previous tsunami hazard assessments in the region used simplified fault models for tsunami simulations, ignoring the detailed 3D fault geometry and slip distribution. To investigate the sensitivity of the tsunami impact and eventually of the hazard to these complexities, we have