Collaborative Research - Sediment pathways, sedimentation processes, and structural growth along the Tohoku segment of the Japan subduction margin: Role of megathrust earthquakes

合作研究 - 日本俯冲边缘东北段的沉积路径、沉积过程和结构生长：巨型逆冲地震的作用

• 批准号: 1436503
• 负责人: Marie-Helene Cormier
• 金额: $ 8.1万
• 依托单位: University of Rhode Island
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-08-01 至 2017-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1436503&HistoricalAwards=false
• 关键词: Collaborative; Research; Sediment; pathways; sedimentation

While tectonic activity, climate, sea-level fluctuations, and anthropogenic activity are most often cited as important agents that control sediment transport and depositions, the role of earthquakes as agents of sediment dispersal and accumulation at active margins may be underappreciated. The 2011 Tohoku earthquake at the Japan Trench was one of the largest megathrust ruptures this century. Because the Japanese subduction system is exceptionally well instrumented, an unprecedented wealth of data are accumulating that document pre-seismic, co-seismic, and post-seismic conditions, providing the first opportunity to quantify environmental changes resulting from a megathrust earthquake. This project will integrate the analysis of existing sediment cores and geophysical data collected in the rupture area of the 2011 earthquake to unravel the contributions of coseismic sedimentation to the stratigraphy of the Japan Trench slope. The Japan Trench is the focus of a coordinated, long-term research program in Japan, and results from this study will contribute usefully to future investigations as well as strengthen an existing international collaboration. Japanese colleagues have already provided the Principle Investigators with recently acquired geophysical data and invited one of them to participate in two coring cruises. This project will further the development of underwater paleoseismology, an emerging field compared to land-based paleoseismology. Results from this study will be highly societally relevant as they are expected to contribute to the assessment of seismic hazards at the Japan Trench. They will also be applicable to the assessment of seismic hazards at other oceanic trenches, including three GeoPRISMS's focus sites (Cascadia, Aleutian, and New Zealand trenches) and the deep Puerto Rico Trench.The Principle Investigators have already initiated collaboration with Japanese scientists to investigate the 2011 event, due to a previously funded NSF-RAPID grant. One of the Principle Investigators participated in two sediment sampling expeditions to the Japan Trench in 2013 aboard the R/V NATSUSHIMA. The preliminary analysis of 31 piston cores collected across the trench slope suggests that some of them sampled deposits from the 2011 event and from prior events. Close inspection of multibeam bathymetric data also suggests that variations in sediment characteristics along the trench are systematically correlated with variations in the morphology of the small frontal prism, the feature at the lower trench slope that absorbs most of the tectonic deformation. This project aims to further explore these results. Specifically, the combined analysis will address the following two questions:- What are the sedimentary signatures of great earthquakes across a trench slope?- How do seafloor morphology and tectonic structures affect coseismic sediment dispersal and deposition?By analyzing the sedimentary record of past earthquakes and their relation to seafloor morphology and tectonic structures, this project will contribute simultaneously to two distinct fields of geoscience: the characterization of coseismic sedimentary processes at active margins and submarine paleoseismology.

尽管构造活动，气候，海平面波动和人为活性通常被认为是控制沉积物传输和沉积的重要药物，但地震作为沉积物分散和积累在主动边缘的蓄积的作用可能不足。 2011年日本沟渠的Toohoku地震是本世纪最大的大型巨像破裂之一。由于日本俯冲系统具有异常良好的仪器，因此积累了前所未有的数据，该数据可以证明证据前的，共同的和震中后的状况，这为量化巨型地震造成的环境变化提供了第一个机会。该项目将整合对2011年地震破裂区域中收集的现有沉积物核心和地球物理数据的分析，以揭示Coseismic沉积对日本沟渠地层的贡献。日本的沟渠是日本协调的长期研究计划的重点，这项研究的结果将有效地为未来的调查做出贡献，并加强了现有的国际合作。日本同事已经为原则研究人员提供了最近获得的地球物理数据，并邀请其中一位参加两次加油巡游。该项目将进一步发展水下古介质学的发展，这是一个新兴领域，与陆基的古植物学相比。这项研究的结果将在社会上具有很高的相关性，因为它们预计将有助于评估日本沟渠的地震危害。它们还将适用于其他海洋沟渠的地震危害的评估，包括三个地理格式的焦点网站（卡斯卡迪亚，阿勒列尼和新西兰战es）和Puerto rico Trenchent。原则调查人员已经与日本科学家们合作调查了2011年的活动，因为这是一项先前资助的NESF-frapid nsf-frapid-fapid-fapid-frapid。主要调查人员之一于2013年在R/V Natsushima上参加了两次对日本海沟的沉积物采样探险。对在沟渠上收集的31个活塞核心的初步分析表明，其中一些是从2011年事件和先前事件中取样的沉积物。对多微光测深数据的仔细检查还表明，沿沟渠的沉积物特征的变化与小额叶的形态的变化系统地相关，该特征是吸收大多数构造构造变形的较低沟槽的特征。该项目旨在进一步探索这些结果。具体而言，组合分析将解决以下两个问题： - 沟渠斜坡上大地震的沉积物签名是什么？ - 海底形态和构造结构如何影响coseissic s菌沉积物的散布和沉积？通过分析过去的地震的沉积性记录及其与海洋的建筑物的关系贡献，这是对海洋的形成型的，这是对海洋的形成的独立性，这是如此：在活性边缘和海底古介质学处的coseiscic沉积过程的表征。