Profiling of crustal deformation across the southwest Japan arc

日本西南弧的地壳变形剖面

基本信息

批准号：
14340133
负责人：
TABEI Takao
金额：
$ 7.36万
依托单位：
Kochi University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-14340133/
关键词：
GPS observation Philippine Sea plate Median Tectonic Line Crustal deformation Active fault Plate coupling

项目摘要

The main purpose of this study is to delineate detailed pattern of three-dimensional crustal deformation in the Nankai subduction zone, southwest Japan. Ongoing interseismic deformation in this region is a mixture of short-term crustal shortening in the direction of oblique convergence of the Philippine Sea plate and permanent lateral movement of the forearc block along the Median Tectonic Line(MTL). We constructed two dense Global Positioning System(GPS) networks in the eastern and western parts of Shikoku Island that extended from the Pacific coast to Chugoku district across the MTL. The networks have been configured so that both strain partitioning in the direction of plate convergence and slip distribution along the MTL can be detected. We determined crustal velocities at 36 sites together with those at the nationwide continuous GPS stations in the vicinity.In order to decompose the deformation field into short-term and permanent components, we explicitly model the plate subduction using multi-rectangular fault segments, newly determined plate convergence vector, and depth-dependent plate coupling estimated from thermal model. Residual velocity field after subtracting the crustal shortening caused by plate subduction shows a lateral movement of the forearc block at a rate of about 5mm/yr along the MTL. Closer inspection shows that fault plane of the MTL inclines northward and its upper part is strongly locked to the depth of 15km while stationary slip is occurring below 15km. Plate coupling at the Nankai Trough is estimated very strong in a shallower zone to the depth of 25km, gradually decreasing with depth, and almost disappears below 35km.We published papers in Earth, Planets and Spaces and made several presentations at the meetings of the Seismological Society of Japan, the Geodetic Society of Japan, the American Geophysical Union, and others.

这项研究的主要目的是描述日本西南部南卡俯冲带的三维地壳变形的详细模式。该区域中持续的跨界变形是菲律宾海板倾斜融合方向的短期地壳缩短的混合物以及前臂沿中间构造线（MTL）的永久性侧向运动。我们在Shikoku岛的东部和西部建立了两个密集的全球定位系统（GPS）网络，这些网络从太平洋海岸延伸到MTL的Chugoku区。已经配置了网络，以便可以检测到板块收敛方向的应变分配和沿MTL的滑动分布。我们确定了36个站点的地壳速度，以及在整个在附近的连续GPS站的位置。减去由板俯冲引起的地壳缩短后的残留速度场表明，前臂块的横向运动沿MTL约为5mm/yr。仔细检查表明，MTL的断层平面向北倾斜，其上部强烈锁定至15公里的深度，而固定滑动的发生在15公里以下。在南卡槽的板耦合估计在较浅的区域至25公里的浅区域非常强大，随着深度逐渐减小，几乎消失在35公里以下，我们在地球，行星和空间发表了论文，并在日本地震学会，日本地震学会，美国地球地球宗地，美国地球地球地球群落，美国地球地球学会，美国地球地球地球群落，以及其他介绍中进行了几次演讲。