Comment on “Inner Core Rotation Captured by Earthquake Doublets and Twin Stations” by Yang and Song

Abstract

AbstractYang & Song (2022, https://doi.org/10.1029/2022GL098393) first claimed existence of Earth's inner core differential rotation based on the waveform similarity of two neighboring stations AAK and KZA across an earthquake doublet and then postulated a local velocity gradient at the top of the inner core based on the difference of PKiKP‐PKIKP differential times between the stations and inferred inner core differential rotation rate. In this comment, we collectively analyze the seismic data in the region and add the data of another nearby station HORS into analysis. HORS and KZA, located in an opposite direction away from AAK, consistently exhibit high waveform similarity. Collective analysis of seismic data demonstrates the invalidity of both their logic of claiming existence of inner core differential rotation and their postulation of “a local inner core gradient” to infer differential rotation. Localized and episodic inner core surface change provides a physically consistent explanation to the seismic data.