Variations in Deformational Style at the Toe of the Nankai Accretionary Prism: Relation to Subducting Plate Sediment Thickness and Basement Topography

南开增生棱柱趾部变形样式的变化：与俯冲板块沉积厚度和基底地形的关系

• 批准号: 1658580
• 负责人: Gregory Moore
• 金额: $ 29.97万
• 依托单位: University of Hawaii
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-05-15 至 2021-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1658580&HistoricalAwards=false
• 关键词: Variations; Deformational; Style; Toe; Nankai

This project is designed to help understand the frontal region of the Nankai subduction zone off of Japan, an area that has a documented history of many great earthquakes and tsunami in the past 2000 years. As such, it is currently believed to be endangered by earthquake and tsunami hazards. The Nankai subduction zone is similar in many ways to both the Cascadia and Aleutian subduction zones, but Nankai has a much more extensive data base than either of these U.S. examples. This study will provide information that will help to understand how variations in sediment thickness and type of sediment along subduction zones influence the occurrence of destructive earthquakes and which earthquakes might generate tsunami. The work also will help to understand the regional extent and potential timing of destructive earthquakes not only in Japan, but also along other subduction zones worldwide. This study is in collaboration with the Japan Agency for Marine Earth Science and Technology (JAMSTEC). The project supports the training of a U.S. graduate student. This project is a collaborative effort between the University of Hawaii and the Japan Agency for Marine Earth Science and Technology (JAMSTEC). New JAMSTEC high-resolution seismic reflection data across the central and western Nankai Trough accretionary prism will be processed and interpreted. The Nankai Trough accretionary prism is arguably the best-studied sediment-dominated margin in the world, and thus serves as the type example. As such, the Nankai region has been the focus of numerous studies, including the new effort by JAMSTEC to collect high-resolution seismic reflection lines across the deformation front along the entire system. This study will integrate new interpretations with existing data from two 3D seismic and drilling transects along with all available JAMSTEC geophysical data along and between the transects, especially multichannel seismic reflection, Ocean Bottom Seismograph, multibeam bathymetry and Very Low Frequency seismicity data. The goal is to understand the inter-relations between regional variations of sediment thickness, oceanic crust topography, and deformational structures at the toe of the prism. The work will test the hypothesis that subducting topography, even relatively small irregularities such as small seamounts, causes thickness variations in the subducting hemipelagic and overlying trench turbidite sedimentary sections. This leads to variations in thickness and width within the proto-thrust zone (PTZ) and to discontinuities in ridges within the imbricate thrust zone (ITZ). Subduction of larger seamounts and fracture zones, with greater variations in sediment thickness, cause regional structural variations in the PTZ and ITZ. The project is also designed to determine whether or not these regional variations are correlated with variations in deeper features such as slow slip earthquakes.

该项目旨在帮助了解日本南部俯冲带的额叶区域，该地区在过去2000年中有许多大地震和海啸的历史。因此，目前认为它会受到地震和海啸危害的威胁。 南卡俯冲带在许多方面都与卡斯卡迪亚和阿留申俯冲区相似，但是南卡的数据库比美国这两个例子中的任何一个都要大得多。 这项研究将提供信息，以帮助了解俯冲带沿俯冲带的沉积物厚度和沉积物类型的变化影响破坏性地震的发生以及地震可能会产生海啸。 这项工作还将有助于了解破坏性地震的区域范围和潜在时机，不仅在日本，而且在全球其他俯冲区域。 这项研究与日本海地科学技术机构（JAMSTEC）合作。 该项目支持美国研究生的培训。该项目是夏威夷大学与日本海地科学技术机构（JAMSTEC）之间的合作努力。将处理和解释新的JAMSTEC高分辨率地震反射数据。南卡槽积棱镜可以说是世界上最坦率的沉积物余地，因此是类型的例子。 因此，南卡地区一直是众多研究的重点，包括詹姆斯特（Jamstec）在整个系统沿整个变形方面收集高分辨率地震反射线的新工作。 这项研究将将新的解释与来自两个3D地震和钻孔样品的现有数据以及沿横断面之间和之间的所有可用的JAMSTEC地球物理数据（尤其是多通道地震反射，海底地震仪，多冰片仪，多型地震仪，多型地震测深度以及非常低的频率地震数据）之间的现有数据结合在一起。目的是了解棱镜脚趾的沉积物厚度，海洋外壳地形和变形结构之间的区域变化之间的相互关系。 这项工作将检验以下假设：俯冲地形，甚至相对较小的不规则性，例如小海山，都会导致俯冲的半质量和上覆的沟槽浊度层状沉积物的厚度变化。 这会导致原始区域内（PTZ）内的厚度和宽度的变化，并导致在膜推力区域内（ITZ）内的脊中不连续。较大的海拔和断裂区域的俯冲，沉积物厚度的变化较大，会导致PTZ和ITZ的区域结构变化。该项目还旨在确定这些区域变化是否与较深的特征（例如慢速地震）的变化相关。

项目成果

Bathymetric imaging of protothrust zone along the Nankai Trough

南海海槽原逆冲断层带测深成像

• DOI: 10.1111/iar.12233
• 发表时间: 2018
• 期刊: Island Arc
• 影响因子: 1.5
• 作者: Yamashita, Mikiya;Miura, Seiichi;Moore, Gregory F.;Nakanishi, Ayako;Kodaira, Shuichi;Kaneda, Yoshiyuki
• 通讯作者: Kaneda, Yoshiyuki

Along-strike variations in protothrust zone characteristics at the Nankai Trough subduction margin

南海海槽俯冲边缘原逆冲带特征的沿走向变化

• DOI: 10.1130/ges02305.1
• 发表时间: 2021
• 期刊: Geosphere
• 影响因子: 2.5
• 作者: Tilley, Hannah L.;Moore, Gregory F.;Yamashita, Mikiya;Kodaira, Shuichi
• 通讯作者: Kodaira, Shuichi