Runaway Slip: Understanding Nucleation of Subduction Megathrust Earthquakes and Slow Slip Precursors

失控滑移：了解俯冲巨型逆冲地震和慢滑移前兆的成核

• 批准号: 1347344
• 负责人: Chris Marone
• 金额: $ 11万
• 依托单位: Pennsylvania State Univ University Park
• 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 2016-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1347344&HistoricalAwards=false
• 关键词: Runaway; Slip; Understanding; Nucleation; Subduction

Subduction zone earthquakes where 'runaway slip' allows faulting to rupture from depth all the way up to the seafloor can cause enormous tsunamis that devastate coastal population centers. Not all subduction zone earthquakes develop runaway slip- details of a particular fault's frictional behavior dictate what happens. This study will conduct laboratory experiments to determine how different types of fault rock respond to applied forces. Results could improve understanding of whether some subduction zones are more, or less, likely to generate megathrust earthquakes.Current understanding of the mechanical response to shear stress of fault rock is limited by the lack of measurements on relevant natural samples at in-situ conditions. Laboratory shear measurements will document friction at in-situ pressures and temperatures using natural fault zone material. A transition in clay structure is thought to play an important role, along with mineral fabric and pore fluid pressure. A series of experiments on both crushed samples and intact wafers will be conducted. Start and end microstuctural and geochemical analyses will quantify the shearing impacts. Interpretation will focus on the nucleation phase of megathrust earthquakes. A female postdoctoral scientist will lead the study and the results will contribute to advancing knowledge within the GeoPRISMS program initiative 'Subduction Cycling and Deformation'.

俯冲带地震中的“失控滑动”使断层从深处一直破裂到海底，可能引发巨大的海啸，摧毁沿海人口中心。并非所有俯冲带地震都会发生失控滑移——特定断层摩擦行为的细节决定了会发生什么。这项研究将进行实验室实验，以确定不同类型的断层岩石如何响应所施加的力。结果可以提高对某些俯冲带是否更有可能产生巨型逆冲地震的理解。目前对断层岩石剪应力的机械响应的理解由于缺乏在原位条件下对相关自然样本的测量而受到限制。实验室剪切测量将使用天然断层带材料记录现场压力和温度下的摩擦力。人们认为粘土结构的转变以及矿物结构和孔隙流体压力发挥着重要作用。将在破碎的样品和完整的晶圆上进行一系列实验。开始和结束的微观结构和地球化学分析将量化剪切影响。解释将集中于巨型逆冲地震的成核阶段。一名女性博士后科学家将领导这项研究，其结果将有助于推进 GeoPRISMS 计划倡议“俯冲循环和变形”的知识发展。