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

该项目是对3月11日的9级和7.9级地震、由此产生的海啸波的产生、传播和本州岛北部沿海的淹没，以及Cs-237进入福岛第一核电站沿海水域并向深水扩散时Cs-237浓度的初始路径和变化进行的综合跨学科研究。该方法是使用先进的地震和嵌套的大气/三维耦合海洋环流数值模式和可用的现场测量相结合的方法来模拟这些过程，从3月11日9级地震的初始底部运动到4月12日。在这次33天的模拟中，Cs-137源浓度水平达到峰值，并随着沿海和陆架外浓度水平的增加而下降，这表明了跨陆架输送和陆架-海洋交换过程，潜在的沉积损失和生物积累在近岸地区。不同模式模拟的详细描述、由此产生的海洋环流和水物性输出场以及初步分析将经常被上传到项目网站，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Cs-137和其他放射性核素在太平洋的长期扩散的初始条件。智力优势：3月11日的地震、海啸、沿海洪水和Cs-137最初释放到海洋中的时间和空间范围很广(从几秒到一个月)和空间(从米到100‘S公里)。采用先进模型的多尺度建模方法应该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在快速赠款期间的初始命运和扩散及其对沿海生态系统的影响进行独立评估。广泛影响：这项研究将促进美日在几个海洋科学领域的合作(与Cs-137和其他释放的放射性核素有关的海洋地球物理、物理海洋学和生化)。该团队包括一名日本博士生，预计随着研究的进展，发布在网站上的模型和模型结果将被研究人员、学生和其他人使用。这项研究的一个成果将是一种经过测试的新的地震/3-D海洋联合模型系统，研究人员和沿海规划者可以使用该系统来评估日本以东巨型断裂带未来地震可能引发的海啸洪水。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.