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积棱镜的区域二维和三维地震反射数据，以描述全球发生地球上最大和最具破坏性的地震和海啸的构造背景的典型例子之一。这项工作是南开海槽地震孕育区综合实验(NantroSEIZE)的重要组成部分，它将为综合大洋钻探计划(IODP)计划的浅部无立管钻井和深部立管钻井奠定坚实的科学基础。通过在两个现有的和一个规划的横断面上钻探得到的地面真相，这个地震数据集将提供前所未有的板块边界断层系统的照明，以可视化其几何形状、历史和相关的岩石属性，因为它向下倾斜演变为地震孕育区。沿走向，棱镜更多陆地部分的大规模逆冲推进包正在被描述和关联。这一分析不仅提供了南开海槽的区域地层和构造格架，还使我们能够评估具有全球重要性的俯冲过程，例如海山俯冲/碰撞对吸积棱柱演化的影响。该项目是夏威夷大学和两个日本机构(JAMSTEC和东京大学海洋研究所)共同努力的结果。JAMSTEC已经为我们提供了数千公里的地震线。我们对南开海槽向海的这些数据的分析表明，洋底地形和沉积物厚度及类型都有显着的变化。随着四国盆地海脊和海槽的俯冲，我们的分析正在扩展到追踪南开吸积棱柱的变形。我们正在绘制俯冲基底地形上方发育的相关褶皱和断层图。

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.