How is geometrical complexity in fault zone recorded by geodesy and seismology?

Abstract

Over the last decades, new observations of complex slip dynamics have emerged. We now observe a continuum of transients energy release happening on fault systems, such as slow slip events, LFEs and tremors. Present quasi-dynamic numerical models are capable of producing such complex slip events on fault planes by considering more realistic complex fault geometries. We aim in this study to bridge the gap between source modeling and observations by generating synthetic surface records. For this, we consider a fault system which consists of a main self-similar rough fault, surrounded by a dense network of off-fault fractures. We embed our 2D quasi-dynamic fault zone in a 3D elastic half-space and cover the free surface with a wide array of colocated broadband accelerometers and high rate GPS stations. Over multiple seismic cycles, we record broadband signals at 50 Hz and high rate GPS at 1 Hz. We aim to understand how the different sequences of complex behavior that we observe on the fault plane are recorded on the stations. What are the different contributions of the main fault and off-fault fractures to the radiated signals recorded on the stations?