Study Rebuts 1-Second Deep-Earth Shifts as Seismic Artifacts

1 articles · Updated · Nature.com · Sep 21

A new analysis says reported decadal changes in the lowermost mantle and outer core can be largely explained by data artifacts, not real structural shifts deep inside Earth.
The authors traced the signals to two main problems: imperfect repeatability between earthquake pairs and station-related timing or sensor issues that can mimic travel-time changes.
For the 2022 outer-core claim, they found a 5.2-km source-depth difference could explain about 0.6 seconds of the roughly 1-second SKS shift, with the remaining mismatch within estimated uncertainty.
For the 2025 lowermost-mantle claim, co-located sensors at station IU.SDV showed misalignments around 0.1 seconds—matching the size and pattern of the reported anomalies.
The study argues extraordinary claims of human-timescale change in the outer core or lowermost mantle need broader cross-validation across multiple ray paths and stricter exclusion of instrument and source effects.