CAREER: Investigating the Relationship between Fault Damage Zones and Earthquakes through Seismic Observations and Earthquake Cycle Simulations

断层不是单一的平面，而是大量的岩石，其中包含厘米厚的断层核，周围是数百米厚的断裂岩石，称为断层破坏带。在世界范围内发现，主要断层周围的断层破坏带通过地震和地震变形容纳了很大一部分板块运动。然而，对断层破坏带与震源过程之间的联系知之甚少，仍然是一个阻碍地震物理研究和地震减灾进展的根本问题。利用新的断层带成像方法和全动态地震周期模型相结合，该项目旨在了解断层破坏带如何影响发生在几秒钟内的地震的产生，以及断层破坏带的结构如何在地震和震间滑动的影响下涉及数百年。该计划亦将促进和丰富广大学生的学习经验，增加地球物理专业学生的多样性。该研究立足于地震数据分析、地震建模和断裂带地质学的交叉领域，为各方面的研究提供了一个独特的机会，促进了不同研究团体之间的交流。目前对震源物理的认识受到断层破坏带空间分布及其对地震活动性和震间形变影响的限制。以前的断裂带研究依赖于近断层地震阵列来获得阵列位置的横截面视图。该项目将对断层破坏带的沿走向变化进行成像，并利用宽带地震网络描述现场效应，以调查断层破坏带是否强烈影响地震活动模式。该项目还将通过考虑断裂带波对震源谱的影响，提高对应力降变化的认识。此外，以前对断裂带地震的模拟要么使用任意应力条件来模拟单次地震，要么使用没有动力波的地震循环。该项目将通过考虑损伤流变学和断裂带波场的动力效应来模拟地震和震间变形。地震观测和地震周期模拟将共同揭示断层损伤带如何影响震源过程，以及地震和震间变形如何促进断层损伤带的形成。此外，该项目将包括研究生设计和领导与地球营研究相关的动手地球物理活动，地球营是UM的一个外展项目，提供为期一周的经验，以教育代表性不足的高中生。通过在本科一年级研讨课中引入招贴会，促进非理科生与研究生之间的交流，并通过在本科和研究生高年级课程中开展研究课题，加强学生的研究能力。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Instead of single planes, faults are volumes of rocks containing centimeters-thick fault cores surrounded by hundreds-meter-thick fractured rocks, called fault damage zones. As discovered worldwide, fault damage zones around major faults accommodate a significant portion of plate motion through seismic and aseismic deformation. However, the poorly understood link between fault damage zones and earthquake source processes remains a fundamental issue that hinders the advancement of earthquake physics research and seismic hazard mitigation. Using a combination of new fault zone imaging methods and fully dynamic earthquake cycle models, the project aims to understand how fault damage zones impact the generation of earthquakes that occur within seconds and how the structure of fault damage zones involves over hundreds of years under the influence of earthquakes and interseismic slip. The project will also promote and enrich the learning experiences of a wide range of students and increase the diversity of students majoring in geophysics. The research lies on the interface of seismic data analysis, earthquake modeling, and fault zone geology, providing a unique opportunity to synergize various research facets and promote communication between different research communities.The current understanding of earthquake source physics is limited by the lack of constraints on the spatial distribution of fault damage zones and their effects on seismicity and interseismic deformation. Previous fault zone studies have relied on near-fault seismic arrays to obtain a cross-sectional view at the array location. The project will image the along-strike variation of fault damage zones and characterize site effects using broadband seismic networks to investigate whether fault damage zones strongly affect seismicity patterns. The project will also improve the understanding of stress drop variation by considering the effects of fault zone waves on earthquake source spectra. Moreover, previous simulations of earthquakes in fault zones have modeled either single earthquakes using arbitrary stress conditions or earthquake cycles without dynamic waves. The project will model earthquakes and interseismic deformation by considering damage rheology and dynamic effects of the fault zone wavefield. The seismic observations and earthquake cycle simulations together will unveil how fault damage zones influence earthquake source processes and how earthquakes and interseismic deformation contribute to the formation of fault damage zones. Additionally, the project will involve graduate students to design and lead hands-on geophysical activities related to the research for Earth Camp, a UM outreach program that provides week-long experiences to educate underrepresented high school students. It will promote the communication between non-science majors and graduate students by introducing poster fairs in a first-year undergraduate seminar course, and strengthen the research skills of students by developing research projects in upper-level undergraduate and graduate courses.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.