Rupture process of the 2005 West Off Fukuoka Prefecture, Japan, earthquake
Rupture process of the 2005 West Off Fukuoka Prefecture, Japan, earthquake
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2005年日本福冈县西海域地震的破裂过程
DOI：
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发表时间：
2006
期刊：
影响因子：
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通讯作者：
H. Horikawa
中科院分区：
文献类型：
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作者：
H. Horikawa
2005年日本福冈县以西发生的6.7级地震是一次中等规模的地壳事件。根据强震资料推断了这次地震的破裂过程。无论震中距和方位角如何，初始P波振幅较小，持续时间为2.5 ~ 4s，表明初始破裂明显。根据传播时间分析，初始破裂的持续时间估计为3.3 s。反演分析表明，初始破裂持续3.5s，整个破裂过程在10 s内完成。在震源东南方向出现了一个具有两个滑动量峰值的大滑动区，该大滑动区的位置与走时分析推断的主破裂的起源相一致。震源附近存在少量滑移，破裂速度较慢。这次地震的地震矩估计为5.7 × 1018 Nm（Mw 6.4）。从推导的滑移分布计算的最大应力降超过10 MPa。负应力降区扩大，对应于小滑移的分布。观测波形的正演模拟表明，负应力降并不完全归因于少量滑动的反演分析分辨率差。由于震源附近的动应力降应该是正的，因此破裂在整个断层上传播，因此愈合后出现负应力降是合理的。
The 2005 West off Fukuoka Prefecture, Japan, earthquake (MS 6.7) is a moderate-size crustal event. The rupture process of this earthquake was inferred from strong motion data. It is observed regardless of epicentral distance and azimuth that the initial P-wave with a small amplitude continued for 2.5–4 s, suggesting prominent initial rupture. The duration of the initial rupture was estimated to be 3.3 s from travel time analysis. Inversion analysis shows that the initial rupture continued for 3.5 s and the overall rupture finished within 10 s. An area of large slip with two peaks of slip amount appeared to the southeast of the hypocenter, and the location of the large-slip area is consistent with the origin of the main rupture inferred from travel time analysis. Small amount of slip was found at and around the hypocenter, and the rupture velocity was slow there. The seismic moment of this earthquake was estimated to be 5.7 × 1018 Nm (Mw 6.4). The maximum stress drop calculated from the derived slip distribution exceeded 10 MPa. An area of negative stress drop expanded, corresponding to the distribution of small slip. Forward modeling of the observed waveforms suggests that the negative stress drop is not fully attributable to poor resolution of inversion analysis for small amount of slip. Since dynamic stress drop should be positive around the hypocenter so that rupture propagates over the entire fault, it is plausible that the negative stress drop appeared after healing.