Effect of seamount subduction on fault geometry and rupture propagation

海山俯冲对断层几何形状和破裂扩展的影响

• 批准号: 1349586
• 负责人: Christine Regalla
• 金额: $ 8.7万
• 依托单位: Regalla Christine A
• 依托单位国家: 美国
• 项目类别: Fellowship Award
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-07-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1349586&HistoricalAwards=false
• 关键词: Effect; seamount; subduction; fault; geometry

Dr. Christine Regalla has been awarded an NSF Earth Sciences Postdoctoral Fellowship to carry out a research and education plan while at McGill University in Montreal, Canada. She will investigate the role of variable fault geometry and strength in the vicinity of subducted seamounts on the nucleation and propagation of megathrust ruptures. This work has direct implications for understanding processes controlling the nucleation and maximum magnitude of large megathrust earthquakes. Subduction zones generate the world's largest earthquakes and tsunamis and the limits on earthquake size depend in part on the geometry of the fault boundary between the two plates. Rough spots and bumps such as seamounts on the down-going plate can affect the degree of locking along the plate boundary fault and modulate the magnitude and distribution of plate boundary slip during earthquakes. Results from this project can be applied to seismic hazard assessments to help estimate maximum rupture area and moment magnitude at megathrusts with subducted seamounts. This project will create opportunities for knowledge sharing between field and modeling-based research groups, and will provide valuable professional development for Regalla as an early-career scientist. In addition, this project will involve undergraduate student researchers, thereby providing opportunities for Regalla to develop educational and mentoring skills, and provide hands-on research opportunities for undergraduate students. Although the subduction of seamounts is common, there is considerable debate as to whether seamounts act as sites of earthquake nucleation or barriers that impede rupture propagation. This work will combine analyses of field outcrops of ancient plate boundary thrust faults that were active during seamount subduction with finite element models of dynamic rupture to evaluate proposed models of earthquake rupture. This project will provide the first known descriptions of the physical properties of the subduction thrust in locations where ancient seamounts have subducted to seismogenic depths, and will provide observationally-based model constraints for fault geometry and strength parameters in numeric simulations of rupture involving subducted seamounts. Results of this work will provide information on the structural accommodation of subducted seamounts and their control on earthquake rupture propagation.The fellowship is being co-funded with the Office of Integrated and International Activities - International Science and Engineering

克莉丝汀雷加拉博士已被授予美国国家科学基金会地球科学博士后奖学金，以开展研究和教育计划，而在加拿大蒙特利尔麦吉尔大学。 她将研究俯冲海山附近断层几何形状和强度变化对巨型逆冲断层破裂的成核和扩展的作用。这项工作有直接的影响，了解过程控制的成核和最大震级的大型逆冲断层地震。 俯冲带产生世界上最大的地震和海啸，地震规模的限制部分取决于两个板块之间断层边界的几何形状。下行板块上的粗糙点和隆起，如海山，可以影响板块边界断层沿着的锁定程度，并在地震时调制板块边界滑动的大小和分布。 该项目的结果可应用于地震危险性评估，以帮助估计具有俯冲海山的巨型逆冲断层的最大破裂面积和矩震级。 该项目将为实地和基于建模的研究小组之间的知识共享创造机会，并将为Regalla作为早期职业科学家提供宝贵的专业发展。 此外，该项目将涉及本科生研究人员，从而为Regalla提供发展教育和指导技能的机会，并为本科生提供动手研究的机会。虽然海山的俯冲很常见，但关于海山是地震成核的场所还是阻碍破裂传播的屏障，存在着相当大的争议。 这项工作将结合联合收割机的古板块边界逆冲断层，在海山俯冲活动与动态破裂的有限元模型，以评估地震破裂的建议模型的现场露头的分析。 该项目将首次提供已知的关于古海山已俯冲到地震发生深度的地点的俯冲逆冲断层物理特性的描述，并将在涉及俯冲海山的破裂数值模拟中提供断层几何形状和强度参数的观测模型限制。这项工作的结果将提供关于俯冲海山的结构调节及其对地震破裂传播的控制的资料。