Collaborative Research: Linking slip dynamics to off-fault deformation in strike-slip fault systems

储存的能量沿着大规模断层释放，比如圣安德烈亚斯断层，在地震中会突然发生。但是，这种储存的能量也可以通过稳定的、周期性的能量释放，即所谓的“慢地震”，以及通过断层周围地区的变形来释放。该项目研究断层如何移动或“滑动”的变化是否与断层周围地区变形的可观察变化有关。实验室中的物理实验用于复制圣安德烈亚斯断层系统的各个方面，以隔离控制变形的各个因素，并了解断层如何滑动与变形发生地点之间的关系。了解变形在断层本身和周围区域之间的分布对于预测区域地震危险性至关重要。这个多机构项目支持五名学生（高中、本科和研究生水平），并开发新的计算工具，用于可视化实验结果，沿着中学地球科学课程的课程活动。这个项目的地质动机源于加州中部的观测，位于圣安德烈亚斯断层系统的两侧，那里的滑动行为沿着断层的走向发生变化，在滑移行为的转换附近，断层外变形的方式发生了变化。然而，天然变形系统是复杂的，滑移行为和边界变形之间的因果关系很难表现出来。为了简化问题，该项目在实验室中结合了一系列物理实验，控制边界条件和材料特性。这种方法有助于评价（1）断层外变形的模式，（2）地质结构如何发展，（3）系统是否达到稳态几何形状，（4）滑动速率是否影响变形模式，以及（5）某些结构是否可以诊断滑动控制。该模型的结果可以提供指导方针的特征结构，以寻找在边界的岩石圈规模的断层，以证明滑动控制的断层外deformation.This奖项反映了NSF的法定使命，并已被认为是值得通过评估使用基金会的智力价值和更广泛的影响审查标准的支持。

The release of stored energy along large-scale faults, such as the San Andreas fault, can occur abruptly in an earthquake. But this stored energy can also be released via steady, periodic releases of energy known as "slow earthquakes", as well as through deformation in the regions around the fault. This project examines whether changes in how a fault moves or "slips" are linked to observable changes in the deformation of the regions around the fault. Physical experiments in a laboratory are used to replicate aspects of the San Andreas fault system to isolate individual factors controlling deformation and to understand the relationship between how a fault slips and where deformation occurs. Understanding how deformation is distributed between a fault itself and the surrounding regions is critical for forecasting regional earthquake hazards. This multi-institution project supports five students (high school, undergraduate, and graduate levels), and develops new computational tools for visualizing experimental results, along with curricular activities for middle school Earth Science courses.The geological motivation for this project stems from observations from central California, flanking the San Andreas fault system, where slip behavior changes along the strike of the fault, and the style of off-fault deformation appears to change near the transition in slip behavior. However, naturally deforming systems are complicated, and it is difficult to show causation between slip behavior and borderland deformation. To simplify the problem, this project incorporates a series of physical experiments in the laboratory, where boundary conditions and material properties are controlled. This approach facilitates the evaluation of (1) patterns in off-fault deformation, (2) how geologic structures develop, (3) whether the system reaches a steady-state geometry, (4) whether the rate of slip impacts patterns of deformation, and (5) whether certain structures might be diagnostic of slip control. The model results may provide guidelines for characteristic structures to look for in the borderlands of lithospheric-scale faults to demonstrate slip control of off-fault deformation.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.