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，而是包含厘米厚的断层核心的岩石体积，周围环绕着数百米厚的破裂岩石，称为断层破坏区。正如在世界范围内发现的那样，主要断层周围的断层破坏带通过地震和非地震变形容纳了很大一部分板块运动。然而，断层破坏带与震源过程之间鲜为人知的联系，仍然是阻碍地震物理研究和地震减灾的一个根本性问题。该项目结合使用新的断裂带成像方法和完全动态的地震周期模型，旨在了解在地震和震间滑动的影响下，断层破坏带如何影响在几秒钟内发生的地震的产生，以及断层破坏带的结构如何涉及数百年。该项目还将促进和丰富广泛学生的学习经验，增加地球物理专业学生的多样性。这项研究涉及地震数据分析、地震模拟和断裂带地质学，提供了一个独特的机会，可以协同各种研究方面，促进不同研究群体之间的交流。目前对地震震源物理的理解受到缺乏对断层破坏带的空间分布及其对地震活动和震间变形影响的限制。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断面图。该项目将成像断层破坏带沿走向的变化，并利用宽带地震网络表征场地效应，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层带波对地震源谱的影响来提高对应力降变化的理解。此外，以前对断裂带地震的模拟要么模拟了使用任意应力条件的单一地震，要么模拟了没有动力波的地震周期。该项目将通过考虑断层带波场的损伤流变学和动态效应来模拟地震和震间变形。地震观测和地震周期模拟将揭示断层破坏带如何影响震源过程，以及地震和地震间变形如何促进断层破坏带的形成。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实践地球物理活动，地球营是密歇根大学的一个外展项目，提供为期一周的经验，教育代表不足的高中生。它将通过在本科一年级的研讨会课程中引入招贴会来促进非理科专业学生和研究生之间的交流，并通过在高水平的本科生和研究生课程中开发研究项目来加强学生的研究技能。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.