High frequency waves guided by the subducted plates underneath Taiwan and their association with seismic intensity anomalies
High frequency waves guided by the subducted plates underneath Taiwan and their association with seismic intensity anomalies
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台湾下方俯冲板块引导的高频波及其与地震烈度异常的关系
DOI：
10.1002/jgrb.50071
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发表时间：
2013
期刊：
影响因子：
--
通讯作者：
B.L.N. Kennett and T. Furumura
中科院分区：
文献类型：
--
作者：
Chen;K.;B.L.N. Kennett and T. Furumura
来自俯冲带的地震事件的能量通常与具有持续长尾波的显著大振幅高频信号相关联。这种由俯冲板块引导的具有高波速和高Q值的地震波可以在弧前区域引起令人惊讶的大地震强度。在这项研究中，我们的特点，俯冲菲律宾海板块（PSP）在台湾的指导行为，并探讨其与异常峰值地面加速度（PGA）模式的关系。菲律宾海板块斜向俯冲于台湾东北部之下，使导向现象复杂化。台湾北方近海60 km以上的地震波揭示了波导行为：PandS波列中的大的持续高频（3-10 Hz）信号。随着深度的增加，低频（<1 Hz）初至变得更加重要，特别是对于深度超过100 km的事件。低频开始和随后的高频到达之间的时间间隔随着深度的增加而略有增加，而由于在地壳浅层中的旅行距离不同，该值随台站而变化。与深度相关的高频成分证实了与俯冲板中的波导效应而不是局部位置放大效应的关联。我们试图在这里获得一个可行的量化方案，以确定更高的频率能量的持续时间，这可以被视为菲律宾海板块的指导作用的指标。
Energy from seismic events traveling up a subduction zone is frequently associated with significant large‐amplitude, high‐frequency signals with sustained long coda. Such seismic waves guided by the subducted plate with high wave velocity and high Q can cause surprisingly large seismic intensity in the fore‐arc area. In this study, we characterize the guiding behavior of the subducted Philippine Sea plate (PSP) underneath Taiwan and investigate their relationship with anomalous peak ground acceleration (PGA) patterns. Oblique subduction of Philippine Sea Plate beneath northeast Taiwan complicates the guiding phenomena. Seismic waves from events deeper than 60 km offshore northern Taiwan reveal wave guide behavior: large, sustained high‐frequency (3–10 Hz) signal inPandSwave trains. With increasing depth, a low‐frequency (<1 Hz) first arrival becomes more significant especially for events deeper than 100 km. The time separation between the low‐frequency onset and the later high‐frequency arrival slightly increases with depth, while the value varies with station due to different travel distances in the shallow crust. The depth‐dependent high‐frequency content confirms the association with a waveguide effect in the subducting slab rather than localized site amplification effects. We attempt here to obtain a practicable quantification scheme to determine the duration of higher‐frequency energy, which can be regarded as an indicator of the guiding effect of the Philippine Sea Plate.