Fault damage zone growth in analog models: typology and segment selection process into fault corridors

A better understanding of stress perturbation around faults, strain propagation, and fluid flow in the upper crust require characterization of the evolution of fault damage zones. Numerous studies provide significant amounts of data and description from a broad variety of faults, however, fault damage evolution is not clearly understood.

In this study, we investigate experimentally damage zones dynamic evolution during normal faults population growth. With this aim, we used a sandbox type device and multilayered analog model, monitored by high-resolution cameras. Several types of damage zones are evidenced and we performed an accurate description of their growth from initiation to mature damage. New damage types including conjugate link damage and graben damage are described for the first time and show similarities with observations in nature. We highlight the new concept of “fault system damage” as the increase of deformation and secondary fault density by the interaction of major faults. We also show that fault damage zones grow by segment linkage into corridors of fault segments formed in the first stages of model deformation. Based on these observations, we propose and discuss the new concept of “segment selection in corridors” as the process of the onset of fault maturation and their damage zone development.