Physical and Numerical Experiments of Slip Partitioning under Oblique Strike-slip

斜走滑作用下滑移分区的物理与数值试验

• 批准号: 1550133
• 负责人: Michele Cooke
• 金额: $ 26.99万
• 依托单位: University of Massachusetts Amherst
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-03-01 至 2020-02-29
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1550133&HistoricalAwards=false
• 关键词: Physical; Numerical; Experiments; Slip; Partitioning

Much attention is focused on the main strands of major strike-slip faults, such as the San Andreas Fault in California, for their potential to generate large devastating earthquakes. However, non-strike slip motion associated with these large faults is often accommodated on secondary faults, which may also be the source of large earthquakes as demonstrated in the 2010 Haiti earthquake. The tectonic conditions that cause slip along these secondary faults are not fully understood. This project uses a combination of physical and computer modeling experiments to better understand why slip takes place on these secondary faults rather than the main fault. The proposed research advances desired societal outcomes through: (1) full participation of women and persons with disabilities in STEM through support of a hearing-impaired female PI and a female graduate student; (2) continued mentoring of deaf and hearing-impaired students; (3) improved STEM education through posting of animations from analog experiments on YouTube and web cam broadcast of experiments Google+ Hangouts transmissions; (4) development of a globally competitive STEM workforce through graduate student training; and (5) a better understanding of earthquake hazards along fault systems such as the San Andreas Fault.This project uses physical and numerical experiments to investigate slip partitioning along strike-slip systems within two types of settings, oblique plate motion and restraining bends. Both of these settings are observed to have slip partitioned faults with strike-slip along vertical fault strands and oblique slip along dipping fault strands, but the loading differs between the models. The physical experiments will test the conditions under which strike-slip faults develop outward verging secondary faults. The experiments explore the controls on and thresholds for slip partitioning and will quantify the nature of slip partitioning within these systems. The analog models utilize wet kaolin to simulate a range of oblique strike-slip boundary conditions that explore the conditions for secondary contractional fault development. The physical experiments data include measurements of the evolving horizontal displacement field using digital image correlation, changes in uplift patterns using stereo imaging, measurements of dilational stress using pressure transducers and estimates of relative water flux along faults using an infrared camera. The data from the analog experiments will be used to track the evolution of kinematic efficiency to test if slip partitioned systems accommodate oblique convergence more efficiently than non-partitioned systems. Numerical simulations of the experiments will assess the work budget of the slip partitioned systems and test if the fault systems evolve to minimize work. 3D numerical simulations of the various experimental setups will provide complete stress and strain fields that facilitate calculation of the complete work budget within the system. This will provide insights, for example, on the tradeoffs between work against gravity and internal deformation as the fault system evolves. The combined physical and numerical investigations in this proposed study will provide a critical bridge between theories of slip partitioning under oblique strike-slip and geologic and experimental observations.

许多注意力都集中在主要走滑断层的主要部分，如加州的圣安德烈亚斯断层，因为它们有可能产生大的破坏性地震。然而，与这些大断层相关的非走滑运动往往被次级断层所容纳，这也可能是2010年海地地震中所证明的大地震的震源。引起沿这些次级断层沿着的构造条件尚未完全了解。该项目使用物理和计算机模拟实验相结合，以更好地了解为什么滑动发生在这些次级断层，而不是主断层。拟议的研究通过以下方式推进了预期的社会成果：（1）通过一名听力障碍女性PI和一名女研究生的支持，让妇女和残疾人充分参与STEM;（2）继续指导聋人和听力障碍学生;（3）通过在YouTube上发布模拟实验动画和网络摄像头广播Google+环聊传输实验来改善STEM教育;（4）通过研究生培训培养具有全球竞争力的STEM人才队伍;（5）更好地了解沿着断层系统（如圣安德烈亚斯断层）的地震灾害。本项目使用物理和数值实验来研究两种类型的设置（斜板运动和约束弯曲）内沿沿着走滑系统的滑动分配。观察到这两种设置都具有滑动分区断层，其中走滑沿着垂直断层链和斜滑沿着倾斜断层链，但模型之间的载荷不同。物理实验将检验走滑断层发育外向次级断层的条件。实验探讨控制和阈值滑移分区，并将量化这些系统内的滑移分区的性质。模拟模型利用湿高岭土来模拟一系列斜向走滑边界条件，探索次级收缩断层发育的条件。物理实验数据包括使用数字图像相关的水平位移场的测量，使用立体成像的隆起模式的变化，使用压力传感器的扩张应力的测量和使用红外相机的相对水通量的估计沿着断层。模拟实验的数据将用于跟踪运动效率的演变，以测试滑移分区系统是否比非分区系统更有效地适应倾斜收敛。实验的数值模拟将评估滑移分区系统的工作预算，并测试故障系统是否演变为最小化工作。各种实验装置的3D数值模拟将提供完整的应力和应变场，便于计算系统内的完整工作预算。例如，这将提供有关断层系统演变过程中克服重力的功和内部变形之间的权衡的见解。在这项拟议的研究中，物理和数值相结合的调查将提供一个关键的桥梁理论之间的滑移分割下斜向走滑和地质和实验观测。