Three Neogene phases of strike-slip faulting along the Romeral Fault System have been deduced from the formation of the Irrá Basin, the deformation of its sediments, and rotation of its remagnetised sediments. The corresponding ages and slip-sense of these phases are Late Miocene right-lateral (syndepositional), approximately Pleistocene left-lateral (syndeformational), Pleistocene to recent right-lateral (rotation of the remagnetised Irrá Formation). An additional phase, of left-lateral present-day slip has been deduced from microseismicity activity.