Fluid‐Controlled Tidal Modulation of Aftershocks Following the 2022 M6.8 Luding Earthquake

Abstract Aftershock sequences record how fault zones recover and weaken after earthquakes, but the roles of fluid migration and stress heterogeneity remain difficult to isolate. Earth tides impose predictable stress perturbations and thus provide a natural probe of faults near failure, although their signals are often obscured by aftershock clustering. Here we apply bootstrap‐based spatial spectral analysis to the 2022 M6.8 Luding earthquake sequence to resolve tidal sensitivity. We identify a systematic shift from a fluid‐rich region before the mainshock to the margins of the high‐slip zone, bypassing the rupture core. This pattern suggests coupled interaction between coseismic stress heterogeneity and postseismic fluid redistribution. Elevated pore pressure enhances sensitivity to weak tidal stress in high stress‐gradient regions, whereas permeability contrasts promote localized fluid accumulation and triggering. Our results show that tidal forcing can reveal where postseismic faults are closest to failure, offering an indirect window into fluid migration and fault‐zone weakening.