3D model of dip slip faults loaded by tectonic stress

A numerical 3D finite element model is used to study the effects of the tectonic stress field and lithostatic loading on the dislocations of dip-slip faults. Special contact elements are employed to deal with the fault surfaces, and a Coulomb friction criterion is adopted. The model has been tested with known solutions based on simple fault models embedded in an elastic halfspace. We are able to predict the slip distribution and other quantities such as the moment tensor, which can reproduce data inferred from observed earthquakes. We study both single faults and fault systems focusing on the coseismic stress and postseismic stress diffusion associated with the relaxation of the ductile lower crust. The model is applied to the Umbria Marche sequence (1997) in order to study the interaction between the main shocks fault planes and the spatio-temporal migration of the earthquakes distribution.