Postseismic stress diffusion in Chile and South Peru

By means of a spherical model of global postseismic deformation we perform an analysis of the postseismic stress diffusion process associated with the main seismic events which occurred in Chile and South Peru in the last century. Our aim is to ascertain if the viscoelastic relaxation of the mantle and asthenosphere following the earthquakes, superimposed on the main mechanism of stress accumulation in the lithosphere, that is to say the subduction process, has, in some way, influenced the spatiotemporal pattern of seismic energy release in this region. Our investigations focus particularly on the areas where two important seismic gaps in an advanced mature state can be recognized. We found that the evolution of the postseismic stress might give a satisfactory explanation for the anomalous duration of the seismic quiescence in the gap areas and also for the possible filling of one of these gaps.