Source Fault of the 2007 Chuetsu-oki, Japan, Earthquake
Source Fault of the 2007 Chuetsu-oki, Japan, Earthquake
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DOI：
10.1785/0120090126
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发表时间：
2010-02
影响因子：
3
通讯作者：
H. Miyake;K. Koketsu;K. Hikima;M. Shinohara;T. Kanazawa
中科院分区：
文献类型：
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作者：
H. Miyake;K. Koketsu;K. Hikima;M. Shinohara;T. Kanazawa
2007年日本中树地震是世界上第一次发生在核电站下方的震源断层上的大地震，其特点是震源断层面难以确定。质心矩张量解表明这是一次6.6级反断层地壳地震，共轭断面向西北和东南倾斜。早期的余震定位结果表明，本次地震的震源断裂面可能是西北倾面或东南倾面。我们对观测到的地震记录进行了震源反演和经验格林函数模拟；然而，它们在两个断平面上产生了相似的波形残差。然后，我们利用强震脉冲的走时差确定了地震烈度与震源的相对位置，并重新定位了部署在震源区的海底地震仪观测到的余震。这些结果表明，滑移主要发生在东南倾的断平面上。这一暗示后来得到反思调查结果的证实。在地震中，柏崎刈羽核电站经历了比设计时预期的更强的地面运动。地面运动由三个地震脉冲组成，对应于三个凸起。第一次和第二次脉冲是由破裂传播到植物中产生的，而远距离东南倾断层面上的致密粗糙体及其S波辐射模式是产生显著的第三次脉冲的原因。
The 2007 Chuetsu-oki, Japan, earthquake is the world’s first major earthquake upon a source fault that extends beneath a nuclear power plant and is also characterized by difficulty determining the source fault plane. Centroid Moment Tensor solutions indicate an M w 6.6 reverse-faulting crustal earthquake with conjugate fault planes dipping to the northwest and southeast. Early results of aftershock locations suggest that either northwest-dipping plane or southeast-dipping plane can be the source fault plane of this earthquake. We carried out source inversions and empirical Green’s function simulations of observed seismograms; however, they resulted in similar waveform residuals for the two fault planes. We then determined the relative locations of earthquake asperities to the hypocenter using travel-time differences of strong-motion pulses and relocated the aftershocks observed by ocean bottom seismometers deployed in the source region. These results imply that slips mainly occurred on the southeast-dipping fault plane. This implication was later confirmed by results of reflection surveys. During the earthquake, the Kashiwazaki-Kariwa nuclear power plant experienced stronger ground motions than those anticipated at the time of design. The ground motions consist of three seismic pulses that correspond to three asperities. The first and second pulses arose from rupture propagation to the plant, while the compact asperity on the distant southeast-dipping fault plane and its S -wave radiation pattern are responsible for the significant third pulse.