Crust-mantle coupling in the Gulf of Cadiz (SW-Iberia)



[1] In the Gulf of Cadiz and Cape St. Vincent region at the SW-Iberian margin, seismic catalogues report seismicity down to ∼100 km depth. According to structural models for the region, this includes earthquakes that occur in the uppermost continental mantle. We invert regional waveforms to estimate moment tensors and centroid depths for moderate earthquakes, obtaining eight solutions (Mw 3.8 to 5.3) between 6 and 60 km depth. Moment tensor solutions and previous source estimates show predominately reverse and strike-slip faulting style with ∼NNW-SSE oriented P-axes, close to plate convergence between Africa and Eurasia. We obtain similar stress tensor estimates from crustal and upper mantle earthquakes, both with sub-horizontal, ∼NNW σ1-axes. This indicates analogous deformation in both domains, and that earthquakes are unrelated to any subduction process.