Nucleation, growth, and linkage of faults in oblique rift zones: Results from experimental clay models and implications for maximum fault size

We use scaled clay models to study the temporal evolution of fault populati ons in experiments of moderately oblique (alpha = 60 degrees) and highly ob lique (alpha = 30 degrees) distributed extension, where alpha is the angle between the rift axis and the direction of displacement. Faults nucleate at random heterogeneities, enhancing nucleation of diffuse clusters of new fa ults. In the highly oblique model, clusters of displacement-normal faults f orm parallel arrays, leading to fault growth dominated by tip propagation a nd along-strike linkage until maximum length is achieved. Subsequent growth of rift-subparallel faults leads to a phase of growth characterized by lin kage and formation of branching faults. In the moderately oblique model, cl usters form in a stepping geometry, leading to growth dominated by linkage, Faults nucleate and grow more rapidly, and their growth is less restricted than in the highly oblique model. Our results have implications for the ma ximum size earthquake to be expected in an oblique rift setting.