17:15 〜 18:45
[SCG48-P14] Seismic structure of subducted Kyushu Palau Ridge inferred from Po/So waves
キーワード：九州パラオ海嶺、フィリピン海プレート、Po/So波
The Kyushu-Palau Ridge (KPR) is regarded as a remnant of the proto Izu–Ogasawara (Bonin)–Mariana (IBM) island arc that was separated by back-arc spreading of the Shikoku and Parece Vela Basins about 30-15 Ma (e.g., Okino et al.,1994). The KPR is thought to be subducting beneath Kyushu as a part of the Philippine Sea plate from Hyuganada region (Tahara et al., 2006). Many previous studies speculate the effect of subduction of the KPR on the tectonics of Kyushu area. Despite several geophysical studies, the location of the deep extension of the KPR remains poorly understood.
In a previous study [Shito, 2019; JPGU], subducted part of the Philippine Sea Plate beneath Kyushu area was explored by using the Po/So waves. They found that the Po/So waves propagated beneath Miyazaki Plain show relatively low path-averaged velocities and less high-frequency energy compared to those traveling in the other part of the subducted Philippine Sea plate.
In this study, we use numerical modeling of seismic wave propagation to estimate the seismic structure that explains the observed velocity and energy content of the Po/So waves propagated beneath Miyazaki Plain. The results would provide a key information for tracing the deeper extension of the KPR.
Acknowledgments
The data analyzed in this study were obtained from Hi-net (NIED) stations in Kyushu. The source parameters of the earthquakes were provided by JMA.
In a previous study [Shito, 2019; JPGU], subducted part of the Philippine Sea Plate beneath Kyushu area was explored by using the Po/So waves. They found that the Po/So waves propagated beneath Miyazaki Plain show relatively low path-averaged velocities and less high-frequency energy compared to those traveling in the other part of the subducted Philippine Sea plate.
In this study, we use numerical modeling of seismic wave propagation to estimate the seismic structure that explains the observed velocity and energy content of the Po/So waves propagated beneath Miyazaki Plain. The results would provide a key information for tracing the deeper extension of the KPR.
Acknowledgments
The data analyzed in this study were obtained from Hi-net (NIED) stations in Kyushu. The source parameters of the earthquakes were provided by JMA.