Overview

• An international team from Peking University and the University of Southern California reports peer‑reviewed evidence in Nature based on seismic wave travel‑time changes.
• Analysis of 121 repeat earthquakes near the South Sandwich Islands (1991–2023) points to a transition from early‑2000s superrotation to slower or opposite relative motion beginning around 2008–2009.
• The reversal appears asymmetric, with the recent phase progressing more slowly than the prior eastward motion, indicating dynamics more complex than simple sinusoidal models.
• Findings align with a roughly 60–70 year cycle suggested by earlier work, though the magnitude, mechanism and precise timing remain uncertain.
• Projected effects are gradual, including millisecond‑scale shifts in day length and potential changes in the geomagnetic field that matter for satellites, communications and animal navigation, and scientists see no immediate hazard.