Collaborative Research: Paleoseismic Evidence of Earthquakes and Tsunamis along the Southern Part of the Japan Trench

合作研究：日本海沟南部地震和海啸的古地震证据

• 批准号: 1624551
• 负责人: Benjamin Horton
• 金额: $ 14.34万
• 依托单位: Rutgers University New Brunswick
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-01 至 2020-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1624551&HistoricalAwards=false
• 关键词: Collaborative; Research; Paleoseismic; Evidence; Earthquakes

There is an extensive instrumental, historical, and geological record of tsunamigenic-earthquakes originating from the northern and middle parts of the Japan Trench that documents the last several thousand years of earthquakes and tsunamis, including the magnitude 9 Tohoku earthquake in 2011. This earthquake ruptured five segments along the northern and middle parts of the Trench, but failed to rupture through the southern part, which is near metropolitan Tokyo. The seismic risk for this portion of the trench is uncertain because of the possibility that stress transferred southwards during the 2011 earthquake and that this part of the subduction zone is locked. Furthermore, the instrumental and historical record is sparse with only one tsunamigenic-earthquake on record (CE 1677 Empo earthquake) and lack of long-term geological data. A research team from University of Southern Mississippi and Rutgers University in collaboration with Japanese researchers will employ an innovative combination of field, laboratory (sedimentary, microfossil, and radiometric analyses), statistical, and modeling techniques to a series of possible tsunami deposits in order to determine the tsunami and earthquake history of the southern Japan Trench, data which is very important for anticipating future disasters. Besides providing an improved understanding of seismic risk in the Tokyo region, additional benefits to society include improved STEM education though outreach to middle school students and development of a globally competitive STEM workforce through training of graduate and undergraduate students and post-doctoral fellow mentoring.The detection and characterization of tsunami deposits preserved in coastal sediments provides a long-term record of past earthquakes. This project focuses on three candidate-tsunami sands that are preserved in coastal rice fields in the Kujukuri beaches, a strand plain located on the Boso Peninsula approximately 50 km east of Tokyo. The identification of tsunami deposits using proxy analyses (grain size and microfossil), with Bayesian age-depth models and tsunami simulation models, will resolve whether the southern part of the trench can produce future earthquakes that are similar in size as the 2011 Tohoku event. Well-constrained ages for each candidate tsunami will permit an accurate estimation of the shoreline position, and thus, inundation distance at the time of deposition. By integrating these changing shoreline positions into previously developed tsunami simulation models (e.g., 2011 Tohoku and CE 1677 Empo models), the research team will test whether previous middle/northern or southern trench ruptures could have deposited the tsunami sands on the Boso Peninsula.

对于起源于日本海沟北部和中部的海啸地震，有大量的仪器、历史和地质记录，记录了过去几千年的地震和海啸，包括 2011 年东北地区发生的 9 级地震。海沟的北部和中部有五个部分，但未能突破靠近东京都的南部部分。这部分海沟的地震风险是不确定的，因为2011年地震期间应力可能向南转移，并且这部分俯冲带被锁定。此外，仪器和历史记录很少，仅记录了一次引发海啸的地震（CE 1677 Empo 地震），并且缺乏长期地质数据。南密西西比大学和罗格斯大学的一个研究小组与日本研究人员合作，将采用现场、实验室（沉积物、微化石和辐射分析）、统计和建模技术的创新组合来研究一系列可能的海啸沉积物，以便确定日本南部海沟的海啸和地震历史，这些数据对于预测未来的灾害非常重要。除了提高对东京地区地震风险的了解之外，对社会的其他好处还包括通过向中学生宣传改善 STEM 教育，以及通过研究生和本科生培训以及博士后指导培养具有全球竞争力的 STEM 劳动力。对沿海沉积物中保存的海啸沉积物的探测和表征可以提供过去地震的长期记录。该项目重点关注九十九里海滩沿海稻田中保存的三个候选海啸沙子，九十九里海滩是位于东京以东约 50 公里的房总半岛上的一片平原。使用代理分析（粒度和微化石）、贝叶斯年龄深度模型和海啸模拟模型来识别海啸沉积物，将解决海沟南部未来是否会产生与 2011 年东北事件规模相似的地震。每次候选海啸的严格限制年龄将允许准确估计海岸线位置，从而准确估计沉积时的淹没距离。通过将这些不断变化的海岸线位置整合到之前开发的海啸模拟模型（例如2011年东北和CE 1677 Empo模型）中，研究小组将测试之前的中/北部或南部海沟破裂是否可能在房总半岛沉积海啸沙。