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: Yosuke Ito, Junichi Nakajima
Format: Article
Language:English
Published: Wiley 2023-07-01
Series:Geophysical Research Letters
Subjects:
Online Access:https://doi.org/10.1029/2023GL103577
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author Yosuke Ito
Junichi Nakajima
author_facet Yosuke Ito
Junichi Nakajima
author_sort Yosuke Ito
collection DOAJ
description 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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spelling doaj-art-47f6d51568bc4a4ea8707afb7251bf5d2025-08-20T02:11:58ZengWileyGeophysical Research Letters0094-82761944-80072023-07-015014n/an/a10.1029/2023GL103577Temporal Variations in QP−1 ${Q}_{P}^{-1}$ and QS−1 ${Q}_{S}^{-1}$ Above a Megathrust Following Episodic Slow‐Slip EventsYosuke Ito0Junichi Nakajima1School of Science Earth and Planetary Sciences Tokyo Institute of Technology Tokyo JapanSchool of Science Earth and Planetary Sciences Tokyo Institute of Technology Tokyo JapanAbstract 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.https://doi.org/10.1029/2023GL103577slow‐slip eventsattenuationfluid
spellingShingle Yosuke Ito
Junichi Nakajima
Temporal Variations in QP−1 ${Q}_{P}^{-1}$ and QS−1 ${Q}_{S}^{-1}$ Above a Megathrust Following Episodic Slow‐Slip Events
Geophysical Research Letters
slow‐slip events
attenuation
fluid
title Temporal Variations in QP−1 ${Q}_{P}^{-1}$ and QS−1 ${Q}_{S}^{-1}$ Above a Megathrust Following Episodic Slow‐Slip Events
title_full Temporal Variations in QP−1 ${Q}_{P}^{-1}$ and QS−1 ${Q}_{S}^{-1}$ Above a Megathrust Following Episodic Slow‐Slip Events
title_fullStr Temporal Variations in QP−1 ${Q}_{P}^{-1}$ and QS−1 ${Q}_{S}^{-1}$ Above a Megathrust Following Episodic Slow‐Slip Events
title_full_unstemmed Temporal Variations in QP−1 ${Q}_{P}^{-1}$ and QS−1 ${Q}_{S}^{-1}$ Above a Megathrust Following Episodic Slow‐Slip Events
title_short Temporal Variations in QP−1 ${Q}_{P}^{-1}$ and QS−1 ${Q}_{S}^{-1}$ Above a Megathrust Following Episodic Slow‐Slip Events
title_sort temporal variations in qp 1 q p 1 and qs 1 q s 1 above a megathrust following episodic slow slip events
topic slow‐slip events
attenuation
fluid
url https://doi.org/10.1029/2023GL103577
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AT junichinakajima temporalvariationsinqp1qp1andqs1qs1aboveamegathrustfollowingepisodicslowslipevents