Crustal structure across the coseismic rupture zone of the 1944 Tonankai earthquake, the central Nankai Trough seismogenic zone
Crustal structure across the coseismic rupture zone of the 1944 Tonankai earthquake, the central Nankai Trough seismogenic zone
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DOI：
10.1029/2001jb000424
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发表时间：
2002
影响因子：
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通讯作者：
A. Nakanishi;N. Takahashi;Jin-Oh Park;S. Miura;S. Kodaira;Y. Kaneda;N. Hirata;T. Iwasaki;Masao Nakamura
中科院分区：
文献类型：
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作者：
A. Nakanishi;N. Takahashi;Jin-Oh Park;S. Miura;S. Kodaira;Y. Kaneda;N. Hirata;T. Iwasaki;Masao Nakamura
[0]许多断层模型研究了1944年托南开地震与1946年南开岛地震同震破裂过程的差异。为了了解是什么因素控制了同震破裂带，研究1944年和1946年地震之间破裂带深部地壳结构的差异是很重要的。先前公布的1946年地震破裂带的地壳结构表明，同震破裂延伸到新近系-第四纪增生棱镜。然而，人们对1944年地震破裂带的结构知之甚少。为了获得1944年地震发震带的完整图像，从海洋到陆地对1944年地震推定同震断裂带进行了广角地震调查。我们的地壳结构模型是基于海底地震仪的数据。地壳结构具有俯冲洋壳和以岛弧壳为界的新第三纪-第四纪增生棱柱的特征。新近系-第四纪吸积棱镜在离变形锋50公里的地方厚度最大可达7公里。俯冲的洋壳可以追溯到35公里以下。俯冲角向陆地方向变陡，在岛弧地壳下达到11°。在断裂带的下倾极限处，洋壳俯冲顶部深度为23 km，上倾极限位于岛弧上地壳下方。其他几个俯冲带也公布了类似的上倾和下倾边界结构。
[1] Differences in the coseismic rupture process between the 1944 Tonankai and the 1946 Nankaido earthquakes have been studied by many fault models. To understand what factors control coseismic rupture zones, it is important to investigate differences in deep crustal structures of the rupture zones between the 1944 and 1946 earthquakes. The previously published crustal structure of the rupture zone of the 1946 earthquake shows that the coseismic rupture extends to the Neogene-Quaternary accretionary prism. However, little is known about the structure of the rupture zone of the 1944 earthquake. To obtain a complete image of the seismogenic zone of the 1944 earthquake, a wide-angle seismic survey was performed across the presumed coseismic rupture zone of the 1944 earthquake from ocean to land. Our model for the crustal structure is based on ocean bottom seismographic data. The crustal structure appears characteristic for subducting oceanic crust and a Neogene-Quaternary accretionary prism bounded by an island arc crust. The Neogene-Quaternary accretionary prism reaches a maximum thickness of 7 km at 50 km distance landward from the deformation front. The subducting oceanic crust can be traced down to 35 km. The subduction angle becomes steeper landward, reaching up to 11° beneath the island arc crust. The depth of the top of subducting oceanic crust at the downdip limit of the rupture zone is 23 km, while the updip limit is located beneath the island arc upper crust. Similar structures of the updip and downdip limits are also published for several other subduction zones.