Rupture Propagation and Arrest in Geometrically Complex Fault Systems: Bends, Stepovers, and Damaged Border Zones

几何复杂断层系统中的破裂传播和停止：弯曲、跨步和损坏的边界区域

• 批准号: 0440145
• 负责人: James Rice
• 金额: $ 50万
• 依托单位: Harvard University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-01-01 至 2008-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0440145&HistoricalAwards=false
• 关键词: Rupture; Propagation; Arrest; Geometrically; Complex

A major problem in earthquake science is to understand rupture through geometrically complex fault systems with bends, branches and stepovers. Such complexities exert major control over the propagation and arrest of rupture. The understanding when and how ruptures stop, which is often associated with such features, is central to understanding seismic risk. This study continues recent developments of the theory and modeling of fault fracture at encounters with kinks, bends and offsets between fault segments. That is done with close reference to explaining rupture patterns as observed in field examples. Those include branches and stepovers in major strike-slip earthquakes (e.g., 2001 Kunlun, Tibet, 2002 Denali, Alaska, and 1992 Landers, California), and splay thrust faulting like that documented for the 1944 Nankai, Japan, and 1964 Alaska subduction zones, with implications for tsunami generation. The studies open new frontiers in rupture dynamics and the physics of earthquakes. Those include a basic understanding of how rupture paths are chosen through complex fault systems, and of the formulation of appropriate computational models (based on dynamic finite element and boundary integral equation methodology) to analyze slip propagation through kinks and branches. In such cases there are significant, coupled, dynamic changes in both the normal and shear stress components supported by the fault, which pose new challenges to representing fracture propagation. Progress in correlating theory with field (and sometimes lab) examples is providing new ways of looking at fault geometry and evidence about prestress states, and translating that into predictions about rupture paths. An important issue under study is whether relic fault geometries with branches and other complexities can be used to infer the direction of rupture in past events, which is important for identifying regions of most severe ground motion. Also, the work addresses how damage zones along faults evolve by successive ruptures, and how inelastic processes within such zones may interact back with stress transmission to the rupture front and with the dynamics of propagation to generate high frequency seismic wave emission. The project during the previous funding cycle was also effective in aiding the participation of women in research. That includes the co-PI, a graduate student research assistant, and three visiting student interns who completed research on fault rupture as capstone projects in completion of their degree programs elsewhere.

地震科学中的一个主要问题是通过带有弯曲，分支和踩踏的几何复杂断层系统理解破裂。这种复杂性对破裂的传播和逮捕产生了重大控制。理解通常与这种特征相关的破裂何时以及如何破裂，对于理解地震风险是至关重要的。这项研究继续在与断层段之间的扭结，弯曲和偏移的相遇时，理论和故障断裂的建模的最新发展。这是通过近似地解释破裂模式来完成的，如在现场示例中所见。这些包括主要滑雪地震中的分支和阶梯（例如，2001 Kunlun，西藏，2002年Denali，Alaska，Alaska和1992 Landers，California），以及像1944年Nankai，Japan和1964 Alaska俯冲动物有关的the the of tssunami of Tssunami Generation of Tsunami Generation of 1944 Nankai，Japan和1964 Alaska俯冲动物所记录的。 研究开辟了破裂动力学和地震物理学的新边界。这些包括对如何通过复杂的断层系统选择破裂路径的基本理解，以及制定适当的计算模型（基于动态有限元和边界积分方程方法），以通过扭结和分支分析滑移传播。在这种情况下，正常和剪切应力成分都有明显的，耦合的动态变化，并由断层支撑，这对代表断裂传播的挑战构成了新的挑战。将理论与领域（有时是实验室）的示例相关联的进展是提供了查看断层几何形状和有关预应力状态的证据的新方法，并将其转化为有关破裂路径的预测。研究的一个重要问题是，与分支和其他复杂性的物质断层几何形状是否可用于推断过去事件中的破裂方向，这对于识别最严重的地面运动区域很重要。同样，该工作解决了沿断层的破坏区域如何通过连续破裂而演变，以及此类区域内的非弹性过程如何与压力传播到破裂前部以及传播动力学以产生高频地震波发射的动力。上一个资金周期的项目也有效地有助于妇女参与研究。其中包括Co-Pi，一名研究生研究助理，以及三名来访的学生实习生，他们完成了故障破裂的研究，因为Capstone项目完成了其他地方的学位课程。