Temporal Variations in QP−1 ${Q}_{P}^{-1}$ and QS−1 ${Q}_{S}^{-1}$ Above a Megathrust Following Episodic Slow‐Slip Events
Abstract Recent observations beneath central Japan have shown that periodic fluid drainage occurs during slow‐slip events (SSEs) based on temporal variations in QP−1 above the megathrust boundary of the subducting Philippine Sea slab. However, no previous studies have estimated associated QS−1. A co...
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| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Wiley
2023-07-01
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| Series: | Geophysical Research Letters |
| Subjects: | |
| Online Access: | https://doi.org/10.1029/2023GL103577 |
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| Summary: | Abstract Recent observations beneath central Japan have shown that periodic fluid drainage occurs during slow‐slip events (SSEs) based on temporal variations in QP−1 above the megathrust boundary of the subducting Philippine Sea slab. However, no previous studies have estimated associated QS−1. A comparison of QP−1 and QS−1 can provide clues to the mechanism of seismic attenuation because of different propagation characteristics of the two waves. We estimate temporal variations in QP−1 and QS−1 via spectral analyses of waveform data from November 2009 to August 2021 period. The results indicate that both QP−1 and QS−1 exhibit temporal variations at about 1‐year periodicity and there are systematic differences between QP−1 and QS−1 that QS−1 have smaller values, less insignificant variation, and weaker correlations with SSEs. Furthermore, QP−1/QS−1 increases concurrent with SSEs. These differences suggest that attenuation is caused by the wave‐induced fluid flow. QP−1/QS−1 could be an important parameter for detecting the presence of fluid. |
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| ISSN: | 0094-8276 1944-8007 |