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）的中央地震滑动段是一个独特的天然实验室，可以详细研究地震断层滑动的运动学和动力学。大地测量和地震数据表明，CSAF的行为在一个强烈的时间依赖性的方式，包括发生慢地震，滑动速率的变化，在几年内，和一个复杂的响应区域应力变化。该项目（1）在空间和时间上描述了地震断层滑动的模式，以更好地理解底层断层带过程的物理学，（2）利用区域应力场细微变化对滑动变化的敏感性，以更好地约束断层的本构性质，（3）利用寒武纪断层滑动对下地壳变形性质的敏感性，加深了对下地壳流变学的认识。这项工作包括一个观测计划，以解决运动学的空间变化和时间依赖的断层滑动的CSAF和理论建模程序，允许解释的背景下，断层力学过程，断层相互作用和流变学的滑动模式。本文利用跨中国地震台网的空间大地测量资料、沿断层沿着的微震分布和活动观测资料以及历史形变资料分析，推导了地震断层滑动的时空运动学。运动学信息形成了使用基于过程的建模技术分析CSAF的动力学的基础，以解决许多基础研究问题，包括（1）与时间相关的非线性滑动的行为范围，（2）滑动瞬变与应力边界条件的细微变化的关系，（3）断层带本构性质，（4）浅部滑动分布反映的下地壳流变性及其随时间的长期变化。

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.