Modelling seismicity based on fault geometry: maximum magnitudes and magnitude-frequency distributions.

Investigating clusters of events and geophysical screening often provides limited constraints on fault geometries. This imaging issue prevents the integration of realistic fault zone geometry into earthquake studies, which can affect our capacity to evaluate the role of pre-existing faults on seismicity. This study describes a modelling strategy accounting for realistic fault zone geometries. Our approach uses stochastic methods underpinned by quantitative fault zone parameterization, followed by an assessment of seismicity from simulations of rupture dynamics controlled by fault geometry. This method is used to investigate the role of fault maturity on seismicity for two case studies, including seismicity associated with the reactivation of a pre-existing fault network due to hydraulic fracturing in Harrison County, Ohio, from 2013 to 2015, as well as the natural seismicity associated with the Yushu-Ganzi left-lateral strike-slip fault system in central-eastern Tibet. In the Harrison County case, we analyze the effect of vertical variability in fault maturity and show how more mature faults in the deeper crystalline basement generate higher magnitude seismicity than shallow, immature faults in younger sedimentary rocks. In the Yushu-Ganzi case study, we show how lateral variability in structural maturity, arising from long-term fault propagation and strain rates, leads to different seismicity on individual fault segments. Our findings indicate that fault geometry determines seismic patterns, with rupture length controlled by fault zone geometry rather than fault lengths, and favour the adoption of a structural geological perspective for the integration of realistic fault geometry into seismicity prediction strategies.