Kinematic efficiency of a non‐optimally‐oriented pre‐existing fault system using wet clay experiments

Slip rate of an active fault system is a key parameter to evaluate seismic potential in an earthquake prone area. There exist different methods to calculate fault slip rates, for instance exploiting geodetic data, paleoseismic trenches, or, for blind faults, restoring folds associated with active faults. In some cases, geodetic data are sparse, the active faults are located in area without recent deposits preventing paleoseismic analyses, and do not exist seismic reflection profiles to reconstruct buried folds. In all these cases, we need an indirect method to predict slip rates without using direct data. Two kinds of information are usually available in active areas: geodetic data (e.g. GPS) and basic information on the nature of the faults (e.g. geometry and kinematic). It is known that only a portion of geodetic (regional) strain rate is transferred to a slip on an active fault. To discuss this quantity, it is useful to use the kinematic efficiency ratio, that is the ratio between the regional strain and the slip on a fault (e.g. Hatem et al., 2017). The kinematic efficiency usually increases when a fault system is mature, and it is low at the beginning of fault formation. On the other hand, this efficiency is sensitive to the geometry of faults; for instance, an andersonian fault is more efficient with respect to a non- optimally oriented fault (e.g. inherited fault). In this study we analyze the evolution of fault efficiency of reverse and strike-slip faults differently oriented with respect to the maximum stress axis. To this aim, we use wet clay analogue models.