Structure and evolution of the backstop in the eastern Nankai Trough area (Japan): Implications for the soon‐to‐come Tokai earthquake
Structure and evolution of the backstop in the eastern Nankai Trough area (Japan): Implications for the soon‐to‐come Tokai earthquake
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南海海槽东部地区（日本）逆止器的结构和演化：对即将发生的东海地震的影响
DOI：
10.1111/j.1440-1738.1996.tb00164.x
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发表时间：
1996
期刊：
影响因子：
1.5
通讯作者：
P. Henry
中科院分区：
文献类型：
--
作者：
X. Pichon;S. Wmant;H. Tokuyama;F. Thoué;P. Huchon;P. Henry
我们目前的数据表明，海洋内缩短，现在发生在南部的东海海槽，产生了Zenisu脊也负责形成以前的脊现在埋在大陆边。这个山脊，我们称之为古Zenisu，目前与支撑层相邻，其位置与孕震滑脱的外部界限一致。古Zenisu脊俯冲到楔下方，导致其完全重组，并将其确定为大东海地震破裂带。古Zenisu的形成及其随后的俯冲作用导致了后陆自约2 Ma以来向西北方向的倾斜。这个模型表明，逆止体和可能的楔形体被右旋剪切，因为它们在伊豆-小笠原洋脊与日本的碰撞中被向西南挤压。我们使用从Zenisu到古Zenisu的有限运动来推导出沿着南海海槽的俯冲矢量和Zenisu-伊豆内的缩短矢量。在Zenisu-Izu内吸收的缩短量向东北方向增加。楔形体下方的Zenisu血小板的俯冲矢量相应地从50 mm/年减小到小于20 mm/年，Zenisu体顺时针旋转，极点位于北纬36°，东经139°附近。这也许可以解释为什么在东海地区大地震重复时间明显较长。另一方面，沿着Zenisu逆冲断层的缩短速率为25-35毫米/年，表明那里有很高的地震潜力。
We present data showing that the intra-oceanic shortening now occurring south of the eastern Nankai Trough that has produced the Zenisu Ridge has also been responsible for the formation of a previous ridge now buried below the continental margin. This ridge, that we refer to as Paleo-Zenisu, is presently adjacent to the backstop and its location coincides with the outer limit of the seismogenic decollement. The subduction of the paleo-Zenisu ridge below the wedge has led to its complete reorganization and has given its identity to the Great Tokai earthquake rupture zone. The formation of paleo-Zenisu and its consequent subduction has induced the tilting of the backstop toward the northwest since ca2 Ma. This model suggests that the backstop and possibly the wedge are dextrally sheared because they are extruded southwestward in relation to the collision of the Izu-Bonin Ridge with Japan. We use the finite motion from Zenisu to paleo-Zenisu to derive both the subduction vectors along the Nankai Trough and the shortening vectors within Zenisu-Izu. The amount of shortening absorbed within Zenisu-Izu increases toward the northeast. The corresponding subduction vectors of the Zenisu platelet below the wedge decrease accordingly to the northeast from 50 to less than 20 mm/year and the Zenisu body rotates clockwise with a pole near 36° North, 139° East. This might explain the apparent longer repetition time of great earthquakes in the Tokai area. On the other hand, the 25-35 mm/year obtained for the rate of shortening along the Zenisu thrust indicates a high seismic potential there.