A team of researchers led by Prof. Huajian Yao from the University of Science and Technology of China has uncovered how tidal forces cause significant temporal variations in seismic velocity within fault fracture zones. By analyzing data from the Anninghe fault zone on the Tibetan Plateau’s southeastern margin, the study reveals daily, semi-daily, and monthly patterns in these changes, closely linked to tidal strain. The findings, published in a recent study in National Science Review, could enhance our understanding of earthquake dynamics and seismic hazards.
The researchers employed seismic interferometry techniques on continuous ambient noise data to monitor seismic velocity fluctuations in the Anninghe fault zone. Their analysis identified clear periodic variations, which aligned strongly with theoretical tidal strain models. These fluctuations were most pronounced within the fault zone itself, highlighting its heightened sensitivity to tidal forces.
Further investigation using teleseismic waveforms revealed that the fault fracture zone exhibited higher spectral ratio values compared to the surrounding areas. This indicates greater subsurface fracturing, making the zone more susceptible to tidal influences. The study explains that tidal forces cause tiny fractures to open and close cyclically, leading to decreases in seismic velocity when fractures open and increases when they close.
“Our findings demonstrate how tidal forces can directly influence fault zones, providing a new perspective on earthquake nucleation processes,” said Prof. Huajian Yao, the study’s lead author.
This research sheds light on the dynamic interactions between tidal forces and fault systems, offering critical insights for earthquake prediction and hazard assessment. The team suggests that future studies could explore these mechanisms in other fault zones to further refine seismic risk models.
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