Deformation of the Japanese Islands and seismic coupling: an interpretation based on GSI permanent GPS observations
Deformation of the Japanese Islands and seismic coupling: an interpretation based on GSI permanent GPS observations
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DOI：
10.1046/j.1365-246x.1998.00595.x
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发表时间：
1998-08-01
影响因子：
2.8
通讯作者：
Hashimoto, M
中科院分区：
文献类型：
--
作者：
Le Pichon, X;Mazzotti, S;Hashimoto, M
自1994年以来，地理调查所的永久GPS观测网覆盖了日本列岛的整个地区，本文选择了116个站点，使用1995年运动矢量的解来讨论观测到的变形场的起源。我们使用vlbi确定的鹿岛运动将位移场指向欧亚大陆，并证明其他选择，如鄂霍次克或日本北部的北美板块与数据不兼容。1年的GPS速度远远高于地质限制所允许的速度，因为这些短期测量包括瞬态弹性变形。然而，观测到的大地形变张量与从活动断裂和地震中推断出的形变张量在定性上一致，表明第四纪的永久形变本质上是部分俯冲引起的弹性变形转化为永久塑性变形的结果。然后，我们计算了太平洋和菲律宾俯冲面的地震间载荷引起的日本群岛的弹性变形。耦合带的几何形状及其向下延伸是由太平洋板块的地震分布决定的。对于菲律宾板，我们使用Hyndman等人（1995）提出的几何形状。如果菲律宾海板块的俯冲运动是100%锁定的，如果太平洋板块的俯冲运动是75- 85%锁定的，那么这些弹性模型解释了观测到的大部分速度场。我们注意到，预测的显著弹性变形区（相对于欧亚大陆超过10毫米年（-1）的运动）的边界与主要的永久变形区相吻合：太平洋俯冲弹性变形场的东日本海变形带和南开场的Setouchi/MTL变形带。从长期来看，每个带都可能容纳10- 15mm / l的运动（东日本海的辐合；濑户内/MTL带的走滑）。为了解释这种变形，来自海沟的弹性载荷的影响必须与阿穆尔板块相对于欧亚大陆的5- 10mm / l的运动相结合。由于俯冲地震旋回期间的载荷导致东日本海和濑户内/MTL变形带的应力增加，因此在旋回结束附近，这些区域发生地震的概率可能更高。
The entire area of the Japanese Islands has been covered by the permanent GPS observation network of the Geographical Survey Institute since 1994, In this paper we use a solution for the vectors of motion during 1995 for a selection of 116 stations to discuss the origin of the observed deformation field. We refer the displacement field to Eurasia using the VLBI-determined motion of Kashima and demonstrate that other choices such as the Okhotsk or North American plates for north Japan are not compatible with the data. 1 yr GPS velocities are much higher than geological constraints would allow because these short-term measurements include transient elastic deformation. However, the good qualitative agreement between the observed geodetic deformation tensors and those inferred from active faults and earthquakes suggests that the Quaternary permanent deformation is essentially the result of the transfer of part of the subduction-induced elastic deformation into permanent plastic deformation. We then compute the elastic deformation of the Japanese Islands caused by interseismic loading of the Pacific and Philippine subduction planes. The geometry of the coupled zone and its downward extension are determined from the distribution of earthquakes for the Pacific slab. For the Philippine slab we use the geometry proposed by Hyndman et al. (1995). These elastic models account for most of the observed velocity field if the subduction movement of the Philippine Sea Plate is 100 per cent locked and if that of the Pacific Plate is 75-85 per cent locked. We note that the boundaries of the areas where significant elastic deformation is predicted (more than 10 mm yr(-1) of motion with respect to Eurasia) coincide with the main zones of permanent deformation: the Eastern Japan Sea deformation zone for the Pacific subduction elastic deformation field and the Setouchi/MTL deformation zone for the Nankai field. Each zone probably accommodates 10-15 mm yr-l of motion in the long term (convergence in the Eastern Japan Sea; strike-slip in the Setouchi/MTL zone), To account for this deformation, the effect of elastic loading from the trench must be combined with 5-10 mm yr(-1) of motion of the Amur Plate with respect to Eurasia. Because loading during the subduction earthquake cycle causes an increase in stress in the Eastern Japan Sea and Setouchi/MTL deformation zones, the probability of earthquake occurrence in these zones may be higher near the end of the cycle.