Is the initial thermal state of a fault relevant to its dynamic behavior?

Abstract

The prediction of impending earthquakes undoubtedly remains one of the most pursued goals of modern seismology. Within the framework of a deterministic description of earthquake faulting, the initial state of the fault system and the choice of the governing model describing its rheological behavior play a fundamental role in the description of the earthquake recurrence. In classical models of faulting, this initial state is basically described by the initial shear-stress distribution (prior to the next earthquake event) and by the initial sliding velocity. In this paper, by assuming a rate-, state-, and temperature-dependent rheology, we investigate whether the initial thermal state of the fault can also have a significant role in earthquake dynamics. Our numerical results clearly demonstrate that the initial temperature greatly influences the cosesimic slip (and thus the earthquake magnitude), the released stress (and thus the radiated energy), and the interevent time (i.e., the earthquake recurrence). Despite the remaining issues on the concept of earthquake cyclicity, our results can contribute to the lively debate on the deterministic hazard assessment, illuminating that the temperature field also plays a fundamental role in earthquake dynamics, not only because it controls possible phase changes and the chemical environment of the fault zone, but also because it affects the response of a brittle fault and earthquake cycles.