Advances in Conception about Earthquakes - Earthquake Engineering for Structural Design - page 121

Figure 4.12 Evolution in cascade (Gioncu, 2005)
displacements, producing an earthquake. Immediately after the earthquake and
some time after, the affected parts of the fault plane are in a state of creep,
characterized by faster growth of inelastic displacements, lasting until the stress
falls below some other level and a new stress state begins, due to the external
existing forces.
A seismic region is considered as a system of absolutely rigid blocks of the
lithosphere (solid part of the Earth's crust), which are separated by thin boundary
zones (for instance South American Plate, Fig. 4.13a).