Inputs to the Nankai Trough Seismogenic Zone: Effects of Large-scale Lateral Variations in Basement Topography and Sediment Thickness

正在分析一组横跨南开海槽增生棱柱的区域二维和三维地震反射数据，以描述全球产生地球上最大和最具破坏性的地震和海啸的构造环境的典型例子之一。 这项工作是综合南海海槽地震带实验（NantroSEIZE）的一个重要组成部分，将建立其坚实的科学基础，特别是通过综合海洋钻探计划（IODP）计划的浅无立管钻井和深立管钻井。 通过在两个现有和一个计划中的样带中进行钻探获得的地面实况，该地震数据集将为板块边界断层系统提供前所未有的照明，以可视化其几何形状，历史和相关的岩石特性，因为它向下倾斜进入孕震区。 在棱柱体更向陆地的部分，大规模的推力包正被表征，并沿沿着走向相互关联。 这一分析不仅提供了南海海槽的区域地层和结构框架，它也使我们能够评估全球重要的俯冲过程，如海山俯冲/碰撞对增生棱柱演化的影响。 JAMSTEC已经为我们提供了数千公里的区域地震测线。 通过对南海海槽向海方向资料的分析，揭示了南海海槽基底地形、沉积物厚度和类型的显著变化。 我们的分析被扩展到跟踪变形的南海增生棱柱的脊和槽的四国盆地俯冲。我们正在绘制在俯冲基底地形之上发展的相关褶皱和断层。

A set of regional 2-D and 3-D seismic reflection data across the Nankai Trough accretionary prism is being analyzed to characterize one of the type examples of a tectonic setting that globally generates most of Earth's largest and most destructive earthquakes and tsunamis. This work is a major component of the integrated Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) that will build its solid science base, especially for the shallow non-riser drilling and the deep riser drilling planned through the Integrated Ocean Drilling Program (IODP). With ground-truth from drilling in two existing and one planned transect, this seismic data set will provide unprecedented illumination of a plate boundary fault system to visualize its geometry, history, and associated rock properties, as it evolves down dip into a seismogenic zone. Large-scale thrust packages in more landward parts of the prism are being characterized and correlated along strike. This analysis not only provides the regional stratigraphic and structural framework of the Nankai Trough, it also allows us to assess globally-important subduction processes such as the affect of seamount subduction/collision on accretionary prism evolution.This project is a collaborative effort among the University of Hawaii and two Japanese institutions (JAMSTEC and University of Tokyo Ocean Research Institute). JAMSTEC has already provided us with thousands of kilometers of regional seismic lines. Our analysis of these data seaward of the Nankai Trough has revealed remarkable variations in oceanic basement topography and sediment thickness and type. Our analysis is being extended to track the deformation of the Nankai accretionary prism as the ridges and troughs of the Shikoku Basin are subducted. We are mapping the associated folds and faults that develop above the subducting basement topography.