Stress diffusion along rupturing plate boundaries

An analysis is made of viscoelastic lithosphere/asthenosphere coupling in the time‐dependent redistribution of stress along plate boundaries or other seismic lineaments following great earthquakes. The study is based on a generalization by Rice of Elsasser's model of stress‐diffusion, in which general elastic plane stress deformations are allowed in lithospheric plates which are coupled in an elementary way to a (Maxwellian) viscoelastic asthenosphere. Solutions are developed which describe the large‐scale quasi‐static distribution of thickness‐averaged stresses in the lithosphere at or near stationary or travelling rupture zones, modeled here by either crack‐like zones of fixed stress drop or dislocation‐type slip zones. Sudden ruptures shed load onto the asthenosphere which is gradually transferred back to the lithosphere by a slow relaxation process. The spatial and temporal characteristics of the predicted stress alterations suggest a significant role of lithosphere/asthenosphere coupling effects in triggering interactions of great earthquakes, patterns of prolonged aftershock activity, and the breaking of barriers or gaps by time‐dependent stressing.