Seismic reflection profiling across the seismogenic fault of the 1995 Kobe earthquake, southwestern Japan
Seismic reflection profiling across the seismogenic fault of the 1995 Kobe earthquake, southwestern Japan
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1995 年日本西南部神户地震发震断层的地震反射剖面
DOI：
10.1016/s0040-1951(97)00252-7
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发表时间：
1998
期刊：
影响因子：
2.9
通讯作者：
T. Ikawa
中科院分区：
文献类型：
--
作者：
Hiroshi P. Sato;H. Hirata;T. Ito;N. Tsumura;T. Ikawa
1995年神户(兵库县南部)地震(Mw6.9)地表破裂发生在浅水岛西北海岸的Nojima断层上。Awaji岛北部的余震震中与地表断裂不对齐。暗示了一个复杂的活动断裂结构。为了揭示发震断裂及其伴生活动断裂的结构，在阿瓦济岛北部进行了长41.6公里的垂直地震反射测量。跨Awaji地震反射剖面揭示了该地区下方的断层几何形状。Awaji岛是由东海岸的Kariya断裂运动抬升的，这导致了新近纪盆地的不对称性，西部浅于东部。Awaji岛下方的断裂呈“弹出”或“正花状构造”，基底被两条活动断裂所包围，即西海岸的Nojima断裂和东海岸的Kariya断裂。两者都是具有右旋走滑运动的高角度逆断层。Awaji岛北部的余震群呈Y型震中分布。因此，Nojima和Kariya断裂似乎连接在上地壳中部，深度约7公里，形成了一个孕育地震的主断裂。据报道，在Awaji岛北部的活动断裂上发生了三次重大地震事件：公元前2000年的史前事件、1596年的Keicho-Fushimi地震和1995年的神户地震。根据本研究中观察到的活动断裂的构造关系，我们认为这些事件发生在所提出的中地壳深度的主断裂上。
The 1995 Kobe (Hyogo-ken Nanbu) earthquake (Mw6.9) surface rupture appeared along the Nojima fault on the northwest coast of Awaji Island. The aftershock epicentres in northern Awaji Island are not aligned with the surface faulting. suggesting a complicated active fault structure. To reveal the structure of the seismogenic fault and its associated active faults, a perpendicular 41.6-km-long seismic reflection survey was undertaken across northern Awaji Island. The Trans-Awaji seismic reflection profile reveals the fault geometry beneath the area. Awaji Island was uplifted by movement on the Kariya fault along its east coast, which produced an asymmetry in Neogene basin that is shallower in the western part than in the eastern part. The faults beneath Awaji Island show a ‘pop-up’ or a ‘positive flower structure’ and the basement is bounded by two active faults, the Nojima along the west coast and the Kariya along the east coast. Both are high-angle, reverse faults with a right-lateral, strike-slip movement. The cluster of aftershocks in the northern part of Awaji Island has a Y-shaped hypocentral distribution. The Nojima and Kariya faults thus appear to connect in the middle of the upper crust at about 7 km depth, forming a seismogenic master fault. Three major seismic events have been reported on the active faults in northern Awaji Island: a prehistoric event dated 2000 yr BP, the 1596 Keicho-Fushimi earthquake, and the 1995 Kobe earthquake. Based on the structural relationship of the active faults that we observed in this study, we suggest that these events occurred on the proposed master fault at mid-crustal depth.