Quasi‐static earthquake mechanics

Viewed as a boundary value problem of continuum mechanics, the subject of earthquake mechanics reduces to the study of (1) constitutive properties (stress‐deformation laws) and geometry of fault zones and surroundings, and (2) remotely applied boundary conditions. In the purely quasi‐static formulations described here, a precise criterion for instability leading to dynamic rupture is also needed. The present consensus supports the concept of an earthquake cycle in which the somewhat arbitrarily chosen successive stages are (1) slow increase of stress due to remote loading, (2) the onset, propagation, and cessation of earthquake rupture, and (3) post‐seismic adjustment. Although no single rigorous model yet exists for the complete cycle because of simplifying constitutive assumptions, there are detailed models for each stage.