Decadal change of seismic structure in the Earth's lowermost mantle.
basic_science · Level V
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- Record sourced from PubMed, PMID 41034208.
- Also identified by DOI 10.1038/s41467-025-63814-3 and PMC identifier 12488924.
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Abstract
Studying temporal changes of seismic property could provide a direct mean to monitor dynamic processes in the Earth's lowermost mantle, yet no related seismic observations were discovered. Here, we report temporal changes of seismic data between a pair of nearly co-located earthquakes occurring on 2000/07/07 and 2009/12/17 and infer two types of decadal-scale structural changes in the lowermost mantle: (1) a 10s km-scale shrinkage or movement of an ultra-low velocity zone near the core-mantle boundary, and (2) opposing shear wave anisotropy changes in the top and bottom portions of the lowermost ~300 km mantle. These findings suggest that ultra-low velocity zones are deformed as partially molten materials or moved by vigorous localized material flows and the region of the lowermost mantle possesses a separate layer circulation. This report demonstrates the capability of seismic monitoring of deep mantle dynamics and calls for new geodynamical models to account for these previously unrecognized features.