Collaborative Research: The Japan March 11 Earthquake, Tsunami Inundation, and Initial Spread of Fukushima Dai-ichi Radionuclides into the Pacific Ocean: Model Assessment

该项目是一项全面的跨学科研究，涉及3月11日最初的M=9和M=7.9地震，由此产生的海啸波的产生、传播和沿着北方本州岛的沿海淹没，以及进入沿海地区的初始路径和Cs-237浓度的变化。福岛第一核设施的沿海沃茨水域并穿过大陆架传播到更深的水域。 该方法是使用先进的地震和嵌套耦合大气/3-D海洋环流数值模型加上可用的现场测量相结合，以模拟这些过程从最初的3月11日M=9地震底部运动到4月12日。在这个为期33天的模拟过程中，铯-137源浓度水平达到峰值，并随着沿海和大陆架外浓度水平的增加而下降，这表明跨大陆架迁移和大陆架-海洋交换过程，以及近岸区域潜在的沉积损失和生物积累。各种模型模拟的详细说明、由此产生的海洋环流和水属性输出场以及初步分析将经常上载到项目网站，供对研究区域沿海物理和生物/化学过程感兴趣的其他人使用，并作为研究铯-137和其他放射性核素在太平洋长期扩散的初始条件。3月11日的地震、海啸、海岸淹没和Cs-137最初释放到海洋中，涵盖了广泛的时间（从几秒到一个月）和空间（米到100公里）尺度。采用先进模型的多尺度模拟方法应能对所涉及的关键物理过程进行全面和综合的描述和理解，并对Cs-137的初始归宿和扩散及其在RAPID赠款期内对沿海生态系统的影响进行独立评估。这项研究将促进美日在海洋科学若干领域的合作（海洋生物物理学、物理海洋学和与Cs-137和其他释放的放射性核素有关的生物化学）。该团队包括一名日本博士生，预计随着研究的进展，研究人员、学生和其他人将使用发布在网站上的模型和模型结果。这项研究的成果之一将是一个经过测试的新的地震/三维海洋模型系统，研究人员和沿海规划人员可以使用该系统来评估日本东部巨型逆冲带未来地震造成的潜在海啸洪水。该系统可应用于其他地震和/或海啸多发地区。

This project is a comprehensive interdisciplinary study of the March 11 initial M=9 and M=7.9 earthquakes, the resulting tsunami wave generation, propagation and coastal inundation along northern Honshu Island, and the initial pathways and changes in Cs-237 concentrations as it enters the coastal waters at the Fukushima Daiichi nuclear facility and spreads across the shelf to deeper water. The approach is to use a combination of advanced seismic and nested coupled atmospheric/3-D ocean circulation numerical models plus available field measurements to simulate these processes starting with the initial March 11 M=9 earthquake bottom movement through April 12. During this 33-day simulation, the Cs-137 source concentration levels peaked and decreased towards the increasing coastal and off-shelf concentration levels, indicative of cross-shelf transport and shelf-ocean exchange processes, with a potential sedimentation loss and biological accumulation in the near-shore region. Detailed descriptions of the different model simulations, the resulting ocean circulation and water property output fields and initial analysis will be uploaded to a project website on a frequent basis for use by others interested in coastal physical and bio/chemical processes in the study area and as initial conditions for studies of the long-term spread of Cs-137 and other radionuclides in the Pacific Ocean.Intellectual Merit: The March 11 earthquakes, tsunami waves, coastal inundation, and initial release of Cs-137 into the ocean cover a wide range of time (from seconds to a month) and space (meters to 100's of km) scales. The multi-scale modeling approach with advanced models should produce a comprehensive and integrated description and understanding of the key physical processes involved and an independent assessment of the initial fate and spread of Cs-137 and its impact on the coastal ecosystem within the RAPID grant period.Broader Impacts: This study will foster U.S-Japanese collaboration in several areas of ocean sciences (marine geophysics, physical oceanography, and bio-chemistry related to Cs-137 and other released radionuclides). The team includes one Japanese PhD student, and it is anticipated that the models and model results posted on a website will be used by researchers, students, and others as the study progresses. One outcome of this study will be a tested new combined earthquake/3-D ocean model system that can be used by researchers and coastal planners for assessing potential tsunami flooding from future earthquakes in the megathrust zones east of Japan. This system can be applied to other earthquake and or tsunami-prone areas.