Probability and Recurrence of Maximum Magnitude Based on Stochastic Modeling of Internal Fault Geometry

Abstract

The recognition that relay zones along faults can act as barriers to earthquake propagation implies that rupture size may not be random and earthquakes are constrained by fault geometry. Resolution and observational biases can, however, complicate the integration of actual fault zone geometries into deterministic modeling strategies, thereby negatively impacting earthquake magnitude assessment. This paper describes a statistical modeling strategy as an alternative. The chosen method relies on a stochastic approach combining quantitative fault zone characteristics with a kinematic model linking realistic fault segmentation with expected rupture termination. A sensitivity analysis highlights the effect of fault geometry on rupture sizes, including an increase in the probability of large ruptures, and corresponding changes in the earthquake magnitude‐frequency distribution and associated b‐values, with decreasing degrees of segmentation and increasing fault maturity. Three case studies confirm these effects for the Yushu‐Ganzi‐Xianshuihe fault system, the North Anatolian fault system, and hydraulic fracturing in Ohio. For each case, simulations show first‐order agreement with documented seismicity, including observed magnitude‐frequency distributions, and support the notion that fault characteristics such as relay zone size and internal segmentation are structural controls determining earthquake b‐values and maximum magnitudes. These findings suggest that the incorporation of more realistic fault zone geometries and their impact on rupture cascading could improve seismic risk assessment across various regions.