Effects of strain gradients on asymmetry of experimental normal fault systems

Sandbox experiments were carried out to investigate the influence of horizontal strain gradients on the asymmetry of normal fault systems in regions of crustal extension. During the experiments, faults facing in the direction of higher strain were preferentially developed. The results show that the horizontal strain gradient is an important factor in controlling the asymmetry of normal fault systems. The experiments also relate the degree of asymmetry to the horizontal strain gradient. The results may be applicable to the formation of asymmetric normal fault systems on either side of the axes of mid-oceanic ridges, extensional back-arc regions, and continental rifts.