Displacement-length scaling and fault linkage

Abstract

Large fault systems often result from the linkage of smaller faults. This produces an increase in fault length, but a deviation from the simple displacement pattern observed for individual faults. Here we examine the displacement distribution along a ~7 km long normal fault system composed of overlapping segments, and numerous small splays and non-intersecting subparallel faults. The absence of appreciable sedimentation or erosion associated with this young (<765 ka) fault system allows us to accurately map throw along it. Our results show that the scaling relationship obtained previously for single-segment faults of the same fault population is generally applicable to the fault system described here, if the throw is assessed by adding displacements that occur between segments. We suggest that the smaller faults grew during and after the coalescence of the larger fault segments in order to release large strains in the regions of linkage, thereby maintaining the scaling relationship throughout the growth of the fault system. Although this study was carried out on a relatively small normal fault system, we believe this pattern of fault growth is applicable to all scales as well as to strike-slip and thrust systems.