Kinematics and Dynamics of Time-dependent Slip Along the Central Creeping Segment of the San Andreas Fault

圣安德烈亚斯断层（CSAF）的中央，地震滑动段代表了一个独特的自然实验室，可以详细研究地震断层滑动的运动学和动力学。大地测量和地震资料表明，CSAF表现出强烈的时间依赖性，包括缓慢地震的发生、多年滑动率的变化以及对区域应力变化的复杂响应。(2)利用区域应力场细微变化对断层滑动变化的敏感性，更好地约束断层的本构性质；(3)利用地震断层滑动对下地壳变形性质的敏感性，提高我们对下地壳流变学的认识。这项工作包括一个观测程序来解决CSAF上空间可变和时间相关的断层滑动的运动学问题，以及一个理论建模程序来解释断层机械过程、断层相互作用和流变学背景下的滑动模式。本文从横跨CSAF的空间大地测量数据、沿断层的微震分布和活动观测以及历史形变数据分析中推导出地震断层滑动的时空运动学。运动学信息构成了CSAF动力学分析的基础，使用基于过程的建模技术来解决一些基础研究问题，包括：(1)随时间变化的地震滑动行为范围，(2)滑动瞬态与应力边界条件的细微变化的关系，(3)断裂带本构性质，(3)断层的本构性质。(4)下地壳的流变性反映在浅层滑动分布及其较长期的时间变化上。

The central, aseismically-slipping segment of the San Andreas fault (CSAF) represents a unique natural laboratory allowing detailed investigations of the kinematics and dynamics of aseismic fault slip. Geodetic and seismic data show that the CSAF behaves in a strongly time-dependent fashion including the occurrence of slow earthquakes, variations of slip rates over several years, and a complex response to regional stress changes. This project (1) characterizes the patterns of aseismic fault slip in space and time to better understand the physics of the underlying fault zone processes, (2) utilizes the sensitivity of slip variations from subtle changes in the regional stress field to better constrain the fault's constitutive properties, and (3) benefits from the sensitivity of aseismic fault slip to the nature of lower crustal deformation to improve our understanding of the rheology of the lower crust. The effort includes an observational program to resolve the kinematics of spatially variable and time dependent fault slip on the CSAF and a theoretical modeling program to allow for interpretation of the slip patterns in the context of fault mechanical processes, fault interaction and rheology. The spatio-temporal kinematics of aseismic fault slip are deduced from space geodetic data spanning the CSAF, from observations of micro-earthquake distribution and activity along the fault, and from analysis of historic deformation data. The kinematic information forms the foundation of an analysis of the dynamics of the CSAF using process-based modeling techniques to address a number of fundamental research problems including (1) the range of behaviors of time dependent aseismic slip, (2) the relationship of slip transients to subtle changes in stress boundary conditions, (3) fault zone constitutive properties, and (4) the rheology of the lower crust reflected in the shallow slip distribution and its longer-term variation in time.