Collaborative Research: The Southern San Andreas Fault Zone Experiment

合作研究：南圣安地列斯断裂带实验

• 批准号: 1841315
• 负责人: Yehuda Ben-Zion
• 金额: $ 26.73万
• 依托单位: University of Southern California
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-05-15 至 2023-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1841315&HistoricalAwards=false
• 关键词: Collaborative; Research; Southern; San; Andreas

The San Andreas Fault (SAF) in California is a mature plate boundary fault capable of great (magnitude 8 or greater) earthquakes. The southern section of the SAF has not produced a major earthquake in historic times (over the last 300 years), and is currently believed to pose the largest seismic risk in California. This project will use new seismic and geodetic observations to investigate the sub-surface structure and geometry of the Southern San Andreas Fault (SSAF). In particular, the project will test a hypothesis that the SSAF may not be vertical and may substantial dip to the East. If confirmed, a non-vertical fault dip would have important implications for the mechanics and the long-term tectonic evolution of the SSAF. Better knowledge of the sub-surface geometry of the SSAF will also improve predictions of seismic radiation patterns and the intensity of ground shaking due to future large earthquakes on the SSAF. The broader impacts of this work will be refined estimates of seismic hazard in densely populated areas in Southern California and Mexico as well as support for the education of two graduate students.The researchers from this joint project between the University of California San Diego, Scripps Institution of Oceanography and the University of Southern California, will investigate the fault attitude at depth by imaging a low-rigidity damage zone and/or a bi-material interface associated with the SSAF in the upper crust. This will be accomplished by deploying a dense seismic array spanning the SSAF. Data from the deployed seismic array and regional seismic networks will be used to generate high-resolution tomographic images of the fault zone throughout the seismogenic layer. Seismic data will be combined with high-resolution geodetic observations, including Interferometric Synthetic Aperture Radar (InSAR) and Global Navigation Satellite System (GNSS). A joint analysis of seismic and geodetic data will provide new insights into the spatial extent and degree of damage around a mature plate boundary fault and enable comparisons with observations from other faults in California and elsewhere to examine how the distribution and amount of damage might depend on the fault age, seismic potential, and geometric complexity. The deployment of co-located dense seismic and geodetic arrays will establish a baseline for future measurements of possible time-dependent variations in mechanical properties of rocks comprising the fault zone due to external stress perturbations, which may help constrain the magnitude of absolute stress at seismogenic depth.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.

位于加州的圣安德烈亚斯断层（SAF）是一个成熟的板块边界断层，能够发生大地震（8级或更大）。SAF的南部在历史上（过去300年）没有发生过大地震，目前被认为是加州最大的地震风险。该项目将使用新的地震和大地测量观测来调查南圣安德烈亚斯断层（SSAF）的地下结构和几何形状。特别是，该项目将测试一个假设，即SSAF可能不是垂直的，可能向东倾斜。如果得到证实，非垂直断层倾角将对SSAF的力学和长期构造演化具有重要意义。更好地了解SSAF的地下几何形状也将改善对地震辐射模式和SSAF未来大地震引起的地面震动强度的预测。这项工作的更广泛影响将是对南加州和墨西哥人口密集地区地震危险的精确估计，以及对两名研究生教育的支持。这项由加州圣地亚哥大学、斯克里普斯海洋学研究所和南加州大学联合开展的项目的研究人员，将调查断层的态度，在深度成像低刚度损伤区和/或双材料界面与SSAF在地壳上部。这将通过部署跨越SSAF的密集地震阵列来实现。来自已部署的地震阵列和区域地震网络的数据将用于生成整个孕震层断层带的高分辨率层析成像图像。地震数据将与高分辨率大地测量观测相结合，包括干涉合成孔径雷达（干涉合成孔径雷达）和全球导航卫星系统。地震和大地测量数据的联合分析将为成熟板块边界断层周围的空间范围和破坏程度提供新的见解，并与加州和其他地方的其他断层的观测结果进行比较，以研究破坏的分布和数量如何取决于断层年龄、地震潜力和几何复杂性。在同一地点部署密集的地震和大地测量阵列，将为今后测量构成断层带的岩石由于外部应力扰动而可能出现的随时间变化的机械特性建立基线，该奖项反映了NSF的法定使命，并通过使用基金会的智力价值进行评估，被认为值得支持和更广泛的影响审查标准。

项目成果

Eikonal Tomography of the Southern California Plate Boundary Region

• DOI: 10.1029/2019jb017806
• 发表时间: 2019-09
• 期刊: Journal of Geophysical Research: Solid Earth
• 作者: H. Qiu;F. Lin;Y. Ben‐Zion

Tectonic Inheritance With Dipping Faults and Deformation Fabric in the Brittle and Ductile Southern California Crust

• DOI: 10.1029/2020jb019525
• 发表时间: 2020-07
• 期刊: Journal of Geophysical Research: Solid Earth
• 作者: V. Schulte‐Pelkum;Z. Ross;K. Mueller;Y. Ben‐Zion

General Seismic Architecture of the Southern San Andreas Fault Zone around the Thousand Palms Oasis from a Large-N Nodal Array

从大 N 节点阵列观察千棕榈绿洲周围南圣安德烈亚斯断层带的一般地震结构

• DOI: 10.1785/0320210040
• 发表时间: 2022
• 期刊: The Seismic Record
• 作者: Share, Pieter-Ewald;Qiu, Hongrui;Vernon, Frank L.;Allam, Amir A.;Fialko, Yuri;Ben-Zion, Yehuda
• 通讯作者: Ben-Zion, Yehuda