Pattern of Inner‐Core Differential Rotation From Long‐Term Earthquake Sequences and USArray Network

Abstract How the differential rotation of the Earth's inner core (IC) has changed over time provides insights into the dynamics of the Earth's interior. Analyses of repeating earthquakes (doublets) have yielded different models. Here we present an event‐based investigation using individual events from long‐term earthquake sequences, which improves temporal coverage over doublet‐based approaches and provides spatial resolution for inferring the rotation rate. Results from two pathways, South Sandwich Islands to Alaska (1982–2024) and Kuril Islands to Argentina (1994–2024), reveal a consistent pattern that the IC successively rotated faster than the mantle by about from the early 1980s and decelerated to a near‐zero rate around 2000, perhaps slower than the mantle after about 2010. We also provide a new way to calibrate spatial structure and constrain the average rotation rate with improved accuracy. The results are consistent with the multidecadal IC oscillation model, but do not support shorter‐term oscillations or bursts.