Fluid‐Driven Fault‐Valve Behavior Controls Clustered Paleoearthquakes in a Stable Continental Region: Insights From the Liuyuan Fault, Beishan

Abstract

Abstract

Abstract Stable continental regions (SCRs) are characterized by low strain rates and long earthquake recurrence intervals, but the patterns and drivers of their seismicity remain debated. This study investigates the rupture history of the Liuyuan fault in the low‐strain Beishan region of China to determine whether SCR earthquakes are regular, clustered, or random. We integrate paleoseismic trenching, IRSL and cosmogenic 10 Be dating of trench units and rockfalls, and microstructural analyses of fault‐zone materials. Our results reveal two distinct earthquake clusters at 65.5–46.2 ka and 8.8–4.6 ka, possibly separated by a long period of quiescence, which remains unconfirmed due to a sedimentary record gap. The late Pleistocene cluster is independently corroborated by cosmogenic 10 Be ages of rockfalls, which cluster at 46–48 ka and overlap within uncertainty. Microstructural evidence, including multiple generations of quartz veins and abundant phyllosilicates, points to a fluid‐driven, fault‐valve mechanism. We propose that episodic increases in deep‐sourced fluid pressure, facilitated by a steep fault geometry within a transpressional regime, trigger these rupture clusters. A comparison with other SCRs globally suggests that this clustered behavior, observed in some intraplate settings, may be controlled by key factors: a weakened lithosphere that localizes strain and transient stress perturbations from fluid migration or surface processes. These findings challenge the assumption of time‐independent seismicity in some SCRs and have significant implications for seismic hazard assessment, particularly for critical infrastructure in low‐strain environments like the Beishan region, a proposed site for high‐level radioactive waste disposal.