It is suggested to stimulate the slow relaxation of elastic energy of deformation stress in an earth-quake source by microwave radiation, which intensifies the motion of dislocations, decreases the yield limit, and increases the plasticity. This phenomenon, known in solid-state physics as magnetoplasticity, can be used to retain an earthquake source far from the critical regime capable of developing into a catastrophic earth-quake by stimulating a slow relaxation of the source. The available evidence for the influence of magnetic storms on the dynamics of earthquakes is generally consistent with the concept of stimulated magnetoplasticity as a means of preventing catastrophic earthquakes, proposed in the present communication.