Neotectonic modeling of the Ibero-Maghrebian region

[1] Thin-shell finite element techniques have been applied to model the neotectonics of the Ibero-Maghrebian region, in the westernmost Mediterranean. This region is characterized by a complex seismotectonic pattern and moderate seismic activity associated with the convergence between Africa and Eurasia. We compare two end-member models using different fault networks. Model predictions, including anelastic strain rates, vertically integrated stresses and velocity fields, are compared to the seismicity map and to data on directions of maximum horizontal compression. Best results are obtained assuming a low fault friction coefficient (0.05) and when the Betics and Rif are modeled as parts of the same arc-shaped chain. The highest predicted fault slip rates are in the Tell mountains. Farther to the west, fault slip is more homogeneously distributed over the Betic-Rif chain, Gulf of Cadiz, and Alboran Sea, indicating a diffuse geometry of the plate boundary in this area. The areas of highest predicted strain rates coincide with the most seismically active regions, located in northern Algeria and northeastern Morocco. Our best model also reproduces a major change of the stress regime, from thrusting in the east (Tell mountains) to predominantly strike-slip and normal faulting in the west (Betic-Rif chain and Alboran Sea). The Alboran basin is shown to be undergoing significant internal transpression and therefore cannot be considered as a rigid microplate. The western part of the Alboran Sea and surrounding areas are being extruded to the WNW with respect to Iberia.