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海俯冲带的前沿地区，该地区在过去2000年中有许多大地震和海啸的历史记录。因此，目前认为它受到地震和海啸的危害。 南开俯冲带在许多方面与卡斯卡迪亚和阿留申俯冲带相似，但南开的数据库比美国的这两个例子都要广泛得多。 这项研究将提供信息，有助于了解沉积物厚度和沉积物类型沿着俯冲带的变化如何影响破坏性地震的发生，以及哪些地震可能引发海啸。 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间，不仅在日本，而且在世界各地的沿着其他俯冲带。 这项研究是与日本海洋地球科学和技术机构（JAMSTEC）合作进行的。 该项目支持美国研究生的培训。该项目是夏威夷大学和日本海洋地球科学和技术机构之间的合作项目。将处理和解释新的JAMSTEC高分辨率地震反射数据，该数据横跨南开海槽中部和西部增生棱柱体。南海海槽增生棱柱体可以说是世界上研究得最好的沉积物为主的边缘，因此可以作为典型的例子。 因此，南开地区一直是许多研究的重点，包括JAMSTEC的新努力，收集高分辨率的地震反射线横跨变形前沿沿着整个系统。 这项研究将把新的解释与来自两个三维地震和钻探断面沿着的现有数据以及所有现有的JAMSTEC地球物理数据（沿着和断面之间），特别是多通道地震反射、海底地震仪、多波束测深和甚低频地震活动数据结合起来。目的是了解沉积厚度的区域变化、海洋地壳地形和棱柱体底部变形结构之间的相互关系。 这项工作将检验这样一种假设，即俯冲地形，即使是较小的不规则地形，如小海山，也会造成俯冲半深海层和上覆海沟浊积岩沉积层的厚度变化。 这导致了原冲断带（PTZ）内厚度和宽度的变化，以及叠瓦状冲断带（ITZ）内脊的不连续性。较大的海山和断裂带的俯冲，沉积物厚度的变化较大，造成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更深层次的特征（如慢滑地震）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