The Role of Stress Distribution in Seismic Cycle Complexity of a Long Laboratory Fault

Abstract

A fundamental understanding of the factors controlling the complexity of seismic cycles is crucial to advance the study of earthquake hazard and predictability. Stress distribution and fault system size play a significant role in shaping complex patterns of seismic behavior. This study examines how heterogeneous loading conditions influence the seismic cycles of a long laboratory fault. They are reproduced on analog material in a biaxial apparatus while continuously monitoring the strain field near the fault. By examining the effects of stress variability on fault behavior, we identify a spectrum of rupture outcomes, from periodic, system-size failures to complex seismic sequences comprising several partial ruptures. Additionally, the resulting heterogeneous stress distribution significantly influences single events' rupture dynamics, eventually leading to abrupt rupture slowdown and subsequent delayed re-nucleation. These results provide a framework for understanding the evolution of stress heterogeneity along natural faults and its implications for rupture dynamics and earthquake predictability.