Collaborative Research: Investigating the role of dynamic strain fields in earthquake triggering processes by simulating full wavefield with 3D seismic velocity structures

合作研究：通过使用 3D 地震速度结构模拟全波场来研究动态应变场在地震触发过程中的作用

• 批准号: 2022429
• 负责人: Guoqing Lin
• 金额: $ 18.91万
• 依托单位: University of Miami
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-09-01 至 2024-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2022429&HistoricalAwards=false
• 关键词: Collaborative; Research; Investigating; role; dynamic; Collaborative; Research; Investigating; role; dynamic

Observations of earthquakes caused by perturbations from other earthquakes, both close by and far away, are important for understanding how earthquakes happen and the mechanisms that trigger them. Triggered earthquakes caused by passing seismic waves suggest that earthquake processes are not completely random and independent on disconnected faults. For example, the 2002 Denali magnitude 7.9 earthquake in Alaska triggered abundant earthquakes in the western US. Why do earthquakes correlate with the passing seismic waves, and how do these tiny ground motions cause earthquakes? A better understanding of such processes will help our fundamental understanding of complex earthquake rupture processes and will aid in mitigating seismic hazards by accurately assessing where and when the next earthquake may occur. This project will take advantage of newly developed computational tools and characterizing the relationships between the patterns of the triggered earthquakes and the waves generated by distant earthquakes. The project will develop a new statistical approach to identify triggered earthquakes in southern California and the Caribbean region. The spatial and temporal evolutions of these triggering responses will be examined across multiple fault systems in these regions of interest. The project supports a collaboration between scientists at the University of California, San Diego and the University of Miami. Graduate students, undergraduate students, and postdoctoral fellows will all participate in the project. The work will be of broad interest to those who study earthquakes and their associated hazards. Major earthquakes frequently dynamically trigger seismic events at multiple disconnected faults up to thousands of kilometers away. The correlation between the passing seismic waves and triggered seismicity is robust yet puzzling. A key challenge in understanding dynamic triggering is comparatively characterizing the realistic dynamic strain fields at seismogenic depth and how the associated elevated seismicity evolves through time and space. This project aims to systematically model dynamic strain fields of earthquake sequences and their relation to dynamically triggered earthquakes within a framework of heterogeneous 3D seismic velocity media. The primary goal of the project is to investigate the time-dependent fault zone stress state and fault zone material properties. The project will first identify dynamic triggering cases in southern California and the Caribbean region by developing a new statistical approach that uses distributions of statistics instead of the statistics solely to find significant cases. The project will then simulate realistic dynamic strain fields of these cases with high-resolution 3D velocity models and the SPECFEM 3D algorithms. The project plans to develop a high-resolution body wave velocity model and earthquake catalogs for the Caribbean region. A central element of this work is using the spatiotemporal migration patterns of regional seismicity as tracers of the evolving stress state and material characteristics and cross-examining these patterns with characteristics of the full dynamic wavefields.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.

在附近和遥远的其他地震造成的地震中观察到地震引起的，对于理解地震的发生以及触发它们的机制至关重要。通过地震波引起的触发地震表明，地震过程不是完全随机的，并且独立于断开的断层。例如，2002年Denali级7.9阿拉斯加的地震引发了美国西部的大量地震。为什么地震与经过的地震波有关系，这些微小的地面运动如何引起地震？对此类过程的更好理解将有助于我们对复杂地震破裂过程的基本理解，并通过准确评估可能发生下一次地震的何时何地来帮助缓解地震危害。该项目将利用新开发的计算工具，并表征触发地震的模式与遥远地震产生的波浪之间的关系。该项目将开发一种新的统计方法，以识别南加州和加勒比海地区引发的地震。这些触发响应的空间和时间演变将在这些感兴趣地区的多个故障系统中进行检查。该项目支持加利福尼亚大学圣地亚哥大学和迈阿密大学科学家之间的合作。研究生，本科生和博士后研究员都将参加该项目。研究地震及其相关危害的人将广泛关注这项工作。大地震经常在多个距离数千公里的多个断开断层处动态触发地震事件。传递的地震波和触发地震性之间的相关性是强大而令人困惑的。理解动态触发的一个关键挑战是相对表征地震深度的现实动态应变场，以及相关的升高地震性如何在时间和空间中演变。该项目的目的是在异质3D地震速度介质的框架内系统地模拟地震序列的动态应变场及其与动态触发地震的关系。该项目的主要目标是研究时间依赖性断层区应力状态和断层区域材料特性。该项目将首先通过开发一种新的统计方法来识别南加州和加勒比地区的动态触发案例，该方法使用统计数据的分布而不是统计数据仅用于查找重要病例。然后，该项目将使用高分辨率3D速度模型和SpecFem 3D算法模拟这些情况的现实动态应变场。该项目计划为加勒比地区开发高分辨率的身体波速度模型和地震目录。这项工作的一个核心要素是利用区域地震性的时空迁移模式作为不断发展的压力状态和物质特征的示踪剂，并具有完整动态波场的特征，将这些模式与这些模式进行了交叉检查。这奖反映了NSF的法规任务，并被认为是通过基金会的知识优点和宽广的智能评估来进行评估的，并值得通过评估来进行评估。