フィリピン海スラブの沈み込みに伴う温度・速度構造とスラブ内地震・地表変形の地域性

1.三维温度与流动源代码的开发与建模在二维温度与流动有限差分源代码的基础上，完成了一个三维矩形六面体模型的有限差分源代码的编写。我们对参数进行了无量纲化，并使源代码更快，并开发了计算结果的可视化工具。利用源代码，我们构建了日本西南部温度和水流的三维俯冲模型，考虑了菲律宾海板块过去的俯冲历史、斜向俯冲以及由于距离基南海山链走向的距离不同而产生的不同温度边界条件。通过对观测到的热流数据与计算结果的比较，提出了俯冲菲律宾海板块上表面新的温度分布，并成功地估算了托南凯地震和南开地震的孕震带。2.四国至九州外海板间耦合的估计和地表形变的区域差异检验通过GPS数据的反演分析，揭示了九州地区地壳形变与Hyuganada地区板间耦合的关系。结果发现，九州地区的地壳形变主要表现为别府-岛原地块深部的右旋运动和地幔的东南向拖曳，这是由于冲绳海槽下产生的地幔热柱水平流动以及Hyuganada地区的板间耦合所致。此外，我们还从GPS数据反演中估计了四国附近的板间耦合。我们还估计了1968年Hyuganada(7.5级)地震和1946年南开(8.1级)地震的同震滑移区与本项目获得的板间耦合的空间分布和这些地震的复发时间的关系。

1.Development and modeling of 3-D source code of temperature and flowBased on 2D finite-difference source code of temperature and flow, we completed finite-difference source code of a 3D rectangular parallelepiped model. We non-dimensionalized parameters, parallelized and made the source code faster, and developed visualization tools for calculated results. Using the source code, we constructed 3D subduction model of temperature and flow in southwest Japan, taking account of past subducting history of the Philippine Sea plate, oblique subduction, and different temperature boundary conditions due to difference in distance from the strike of the Kinan seamount chain. Comparing observed heat flow data with calculated ones, we proposed new temperature distribution on the upper surface of the subducting Philippine Sea plate, and succeeded in estimation of seismogenic zone of the Tonankai and the Nankai earthquakes.2.Estimation of interplate coupling off Shikoku to off east Kyushu and examination of regional difference in Earth's surface deformationWe revealed relation between interplate coupling in Hyuganada region and crustal deformation in Kyushu region from an inversion analysis of GPS data. As a result, we found that crustal deformation in Kyushu can be characterized by right-lateral motion at a deeper portion of the Beppu-Shimabara graben and southeastward mantle drag, which would be caused by horizontal flow of mantle plume which is produced under the Okinawa trough, in addition to interplate coupling in the Hyuganada region. Moreover, we estimated interplate coupling off Shikoku from GPS data inversion. We also estimated relation between coseismic slipped region associated with the 1968 Hyuganada (M7.5) and the 1946 Nankai (M8.1) earthquakes and spatial distribution of interplate coupling obtained in this project, and recurrence time of these earthquakes.